First measurement of kaonic helium-4 M-series transitions
F. Sgaramella, D. Sirghi, L. Abbene, F. Artibani, M. Bazzi, D. Bosnar, M. Bragadireanu, A. Buttacavoli, M. Cargnelli, M. Carminati, A. Clozza, F. Clozza, G. Deda, R. Del Grande, L. De Paolis, K. Dulski, L. Fabbietti, C. Fiorini, I. Friscic, C. Guaraldo, M. Iliescu, M. Iwasaki, A. Khreptak, S. Manti, J. Marton, M. Miliucci, P. Moskal, F. Napolitano, S. Niedzwiecki, H. Ohnishi, K. Piscicchia, F. Principato, A. Scordo, M. Silarski, F. Sirghi, M. Skurzok, A. Spallone, K. Toho, M. Tuchler, O. Vazquez Doce, C. Yoshida, J. Zmeskal, C. Curceanu
abstract
In this paper we present the results of a new kaonic helium-4 measurement with a 1.37 g/l gaseous target by the SIDDHARTA-2 experiment at the DAFNE collider. We measured, for the first time, the energies and yields of three transitions belonging to the Mseries. Moreover, we improved by a factor about three, the statistical precision of the 2p level energy shift and width induced by the strong interaction, obtaining the most precise measurement for gaseous kaonic helium, and measured the yield of the L_alpha transition at the employed density, providing a new experimental input to investigate the density dependence of kaonic atoms transitions yield.
SIDDHARTA-2 apparatus for kaonic atoms research on the DAFNE collider
F. Sirghi, F. Sgaramella, L. Abbene, C. Amsler, M. Bazzi, G. Borghi, D. Bosnar, M. Bragadireanu, A. Buttacavoli, M. Carminati, M. Cargnelli, A. Clozza, G. Deda, L. De Paolis, R. Del Grande, K. Dulski, L. Fabbietti, C. Fiorini, I. Friščić, C. Guaraldo, M. Iliescu, M. Iwasaki, A. Khreptak, S. Manti, J. Marton, M. Miliucci, P. Moskal, F. Napolitano, S. Niedźwiecki, H. Ohnishi, K. Piscicchia, F. Principato, A. Scordo, D. Sirghi, M. Skurzok, M. Silarski, A. Spallone, K. Toho, L. Toscano, M. Tüchler, O. Vazquez Doce, C. Yoshida, J. Zmeskal, C. Curceanu
abstract
SIDDHARTA-2 represents a state-of-the-art experiment designed to perform dedicated measurements of kaonic atoms, which are particular exotic atom configurations composed of a negatively charged kaon and a nucleus. Investigating these atoms provides an exceptional tool to comprehend the strong interactions in the non-perturbative regime involving strangeness. The experiment is installed at the DAFNE electron-positron collider, of the INFN National Laboratory of Frascati (INFN-LNF) in Italy, aiming to perform the first-ever measurement of the 2p->1s X-ray transitions in kaonic deuterium, a crucial step towards determining the isospin-dependent antikaon-nucleon scattering lengths. Based on the experience gained with the previous SIDDHARTA experiment, which performed the most precise measurement of the kaonic hydrogen 2p->1s X-ray transitions, the present apparatus has been upgraded with innovative Silicon Drift Detectors (SDDs), distributed around a cryogenic gaseous target placed in a vacuum chamber at a short distance above the interaction region of the collider. We present a comprehensive description of the SIDDHARTA-2 setup including the optimization of its various components during the commissioning phase of the collider.
CdZnTe detectors tested at the DAFNE collider for future kaonic atoms measurements
A. Scordo, L. Abbene, F. Artibani, M. Bazzi, M. Bettelli, D. Bosnar, G. Borghi, M. Bragadireanu, A. Buttacavoli, M. Cargnelli, M. Carminati, A. Clozza, F. Clozza, L. De Paolis, G. Deda, R. Del Grande, L. Fabbietti, C. Fiorini, I. Friščić, C. Guaraldo, M. Iliescu, M. Iwasaki, A. Khreptak, S. Manti, J. Marton, P. Moskal, F. Napolitano, S. Niedźwiecki, H. Ohnishi, K. Piscicchia, F. Principato, Y. Sada, F. Sgaramella, H. Shi, M. Silarski, D. L. Sirghi, F. Sirghi, M. Skurzok, A. Spallone, K. Toho, M. Tüchler, C. Yoshida, A. Zappettini, J. Zmeskal, C. Curceanu
abstract
The SIDDHARTA-2 collaboration at the INFN Laboratories of Frascati (LNF) aims to perform groundbreaking measurements on kaonic atoms. In parallel and beyond the ongoing kaonic deuterium, presently running on the DAFNE collider at LNF, we plan to install additional detectors to perform further kaonic atoms' studies, taking advantage of the unique low energy and low momentum spread K- beam delivered by the at-rest decay of the phi meson. CdZnTe devices are ideal for detecting transitions toward both the upper and lower levels of intermediate-mass kaonic atoms, like kaonic carbon and aluminium, which have an important impact on the strangeness sector of nuclear physics. We present the results obtained in a set of preliminary tests conducted on DAFNE, in view of measurements foreseen in 2024, with the twofold aim to tune the timing window required to reject the extremely high electromagnetic background, and to quantify the readout electronics saturation effect due to the high rate, when placed close to the Interaction Region (IR). In the first test we used commercial devices and electronics, while for the second one both were customized at the IMEM-CNR of Parma and the University of Palermo. The results confirmed the possibility of finding and matching a proper timing window where to identify the signal events and proved better performances, in terms of energy resolution, of the custom system. In both cases, strong saturation effects were confirmed, accounting for a loss of almost 90% of the events, which will be overcome by a dedicated shielding structure foreseen for the final experimental setup.
Characterization of the SIDDHARTA-2 Setup via the Kaonic Helium Measurement
F. Sgaramella, A. Clozza, L. Abbene, F. Artibani, M. Bazzi, G. Borghi, M. Bragadireanu, A. Buttacavoli, M. Cargnelli, M. Carminati, G. Deda, R. Del Grande, L. De Paolis, K. Dulski, C. Fiorini, C. Guaraldo, M. Iliescu, M. Iwasaki, A. Khreptak, S. Manti, J. Marton, M. Miliucci, P. Moskal, F. Napolitano, S. Niedzwiecki, H. Ohnishi, K. Piscicchia, F. Principato, A. Scordo, M. Silarski, D. Sirghi, F. Sirghi, M. Skurzok, A. Spallone, K. Toho, M. Tuchler, J. Zmeskal, C. Curceanu
abstract
The aim of the SIDDHARTA-2 experiment is to perform the first measurement ever of the width and shift induced by the strong interaction to the 2????->1????
energy transition of kaonic deuterium. This ambitious goal implies a challenging task due to the very low X-ray yield of kaonic deuterium, which is why an accurate and thorough characterization of the experimental apparatus is mandatory before starting the data-taking campaign. Helium-4 is an excellent candidate for this characterization since it exhibits a high yield in particular for the 3????->2????
transition, roughly 100 times greater than that of the kaonic deuterium. The ultimate goal of the work reported in this paper is to study the performances of the full experimental setup in view of the kaonic deuterium measurement. This is carried out by measuring the values of the shift and the width for the 3?????2????
energy transition of kaonic helium-4, induced by the strong interaction. The values obtained for these quantities, for a total integrated luminosity of ~31/pb, are epsilon_2????=2.0+-1.2(stat)+-1.5(syst)eV
and Gamma_2????=1.9+-5.7(stat)+-0.7(syst)eV. The results, compared to the value of the shift measured by the SIDDHARTA experiment epsilon_2????=0+-6(stat)+-2(syst)eV, show a net enhancement of the resolution of the apparatus, providing strong evidence of the potential to perform the challenging measurement of the kaonic deuterium.
The SIDDHARTA-2 Veto-2 system for X-ray spectroscopy of kaonic atoms at DAFNE
M. Tüchler, C. Amsler, M. Bazzi, D. Bosnar, M. Bragadireanu, M. Cargnelli, M. Carminati, A. Clozza, G. Deda, R. Del Grande, L. De Paolis, K. Dulski, L. Fabbietti, C. Fiorini, I. Friščić, C. Guaraldo, M. Iliescu, M. Iwasaki, A. Khreptak, S. Manti, J. Marton1, M. Miliucci, P. Moskal, F. Napolitano, S. Niedźwiecki, H. Ohnishi, K. Piscicchia, Y. Sada, A. Scordo, F. Sgaramella, H. Shi, M. Silarski, D. Sirghi, F. Sirghi, M. Skurzok, A. Spallone, K. Toho, O. Vazquez Doce, E. Widmann, C. Yoshida, J. Zmeskal and C. Curceanu
abstract
The Veto-2 is a fundamental component of a multiple-stage veto system for the SIDDHARTA-2 experiment installed at the DAFNE collider at INFN-LNF in Italy. It was developed to improve the signal-to-background ratio for the challenging measurement of X-ray transitions to the fundamental level in kaonic deuterium. Its purpose is the suppression of hadronic background in the form of Minimum Ionizing Particles by using the topological correlation between signals in the X-ray and Veto-2 detectors. The Veto-2 system consists of a barrel of plastic scintillators read out by Silicon Photomultipliers. The system performed its first successful test run within the apparatus with a helium-4 target in 2022. The efficiency of the Veto-2 was determined and found to be 0.62 +- 0.01. The Veto-2 improved the signal-to-background ratio for the kaonic helium-4 L_alpha measurement by about 16%, which is crucial due to the low expected X-ray yield of kaonic deuterium.
Kaonic atoms at the DAFNE collider: a strangeness adventure
C. Curceanu, L. Abbene, C. Amsler, M. Bazzi, M. Bettelli, G. Borghi, D. Bosnar, M. Bragadireanu, A. Buttacavoli, M. Cargnelli, M. Carminati, A. Clozza, G. Deda, R. Del Grande, L. De Paolis, K. Dulski, C. Fiorini, I. Friscic, C. Guaraldo, M. Iliescu, M. Iwasaki, A. Khreptak, S. Manti, J. Marton, M. Miliucci, P. Moskal, F. Napolitano, S. Niedzwiecki, H. Ohnishi, K. Piscicchia, F. Principato, Y. Sada, A. Scordo, F. Sgaramella, H. Shi, M. Silarski, D. L. Sirghi, F. Sirghi, M. Skurzok, A. Spallone, K. Toho, M. Tuchler, O. Vazquez Doce, C. Yoshida, A. Zappettini, J. Zmeskal
abstract
Kaonic atoms are an extremely efficient tool to investigate the strong interaction at the low energy Frontier, since they provide direct access to the K?N interaction at threshold, eliminating the necessity for extrapolation, unlike in the case of scattering experiments. During the 1970s and 1980s, extensive studies were performed on kaonic atoms spanning across a broad spectrum of elements in the periodic table, ranging from lithium to uranium. These measurements provided inputs and constraints for the theoretical description of the antikaon-nuclei interaction potential. Nevertheless, the existing data suffer from significant experimental uncertainties, and numerous measurements have been found to be inconsistent with more recent measurements that utilize advanced detector technology. Furthermore, there remain numerous transitions of kaonic atoms that have yet to be measured. For these reasons, a new era of kaonic atoms studies is mandatory. The DA?NE electron-positron collider at the INFN Laboratory of Frascati (INFN-LNF) stands out as a unique source of low-energy kaons, having been utilized by Collaborations such as DEAR, SIDDHARTA, and AMADEUS for groundbreaking measurements of kaonic atoms and kaon-nuclei interactions. Presently, the SIDDHARTA-2 experiment is installed at DA?NE, aiming to perform the first-ever measurement of the 2p ? 1s x-ray transition in kaonic deuterium, a crucial step towards determining the isospin-dependent antikaon-nucleon scattering lengths. Based on the experience gained with the SIDDHARTA experiment, which performed the most precise measurement of the kaonic hydrogen 2p ? 1s x-ray transition, the SIDDHARTA-2 setup is now fully equipped for the challenging kaonic deuterium measurement. In this paper, we present a comprehensive description of the SIDDHARTA-2 setup and of the first kaonic atoms measurements performed during the commissioning phase of the DA?NE collider. We also outline a proposal for future measurements of kaonic atoms at DA?NE beyond SIDDHARTA-2, which is intended to stimulate discussions within the broad scientific community performing research, directly or indirectly, related to this field.
Potentialities of CdZnTe Quasi-Hemispherical Detectors for Hard X-ray Spectroscopy of Kaonic Atoms at the DAFNE Collider
L. Abbene, A. Buttacavoli, F. Principato, G. Gerardi, M. Bettelli, A. Zappettini, M. Bazzi, M. Bragadireanu, M. Cargnelli, M. Carminati, A. Clozza, G. Deda, R. Del Grande, L. De Paolis, L. Fabbietti, C. Fiorini, C. Guaraldo, M. Iliescu, M. Iwasaki, A. Khreptak, S. Manti, J. Marton, M. Miliucci, P. Moskal, F. Napolitano, S. Niedzwiecki, H. Ohnishi, K. Piscicchia, Y. Sada, F. Sgaramella, H. Shi, M. Silarski, D. L. Sirghi, F. Sirghi, M. Skurzok, A. Spallone, K. Toho, M. Tuchler, O. Vazquez Doce, C. Yoshida, J. Zmeskal, A. Scordo, C. Curceanu
abstract
Kaonic atom X-ray spectroscopy is a consolidated technique for investigations on the physics of strong kaon?nucleus/nucleon interaction. Several experiments have been conducted regarding the measurement of soft X-ray emission (<20 keV) from light kaonic atoms (hydrogen, deuterium, and helium). Currently, there have been new research activities within the framework of the SIDDHARTA-2 experiment and EXCALIBUR proposal focusing on performing precise and accurate measurements of hard X-rays (>20 keV) from intermediate kaonic atoms (carbon, aluminum, and sulfur). In this context, we investigated cadmium?zinc?telluride (CdZnTe or CZT) detectors, which have recently demonstrated high-resolution capabilities for hard X-ray and gamma-ray detection. A demonstrator prototype based on a new cadmium?zinc?telluride quasi-hemispherical detector and custom digital pulse processing electronics was developed. The detector covered a detection area of 1 cm2 with a single readout channel and interesting room-temperature performance with energy resolution of 4.4% (2.6 keV), 3% (3.7 keV), and 1.4% (9.3 keV) FWHM at 59.5, 122.1, and 662 keV, respectively. The results from X-ray measurements at the DAFNE collider at the INFN National Laboratories of Frascati (Italy) are also presented with particular attention to the effects and rejection of electromagnetic and hadronic background.
The KAMEO proposal: Investigation of the E2 nuclear resonance effects in kaonic atoms
L. De Paolis on behalf of M. Bazzi, D. Bosnar, M. Bragadireanu, M. Cargnelli, M. Carminati, A. Clozza, G. Deda, R. Del Grande, K. Dulski, C. Fiorini, I. Frišči`c, C. Guaraldo, M. Iliescu, M. Iwasaki, A. Khreptak, S. Manti, J. Marton, M. Miliucci, P. Moskal, F. Napolitano, S. Nied`zwiecki, O. Ohnishi, K. Piscicchia, Y. Sada, A. Scordo, F. Sgaramella, H. Shi, M. Silarski, D. L. Sirghi, F. Sirghi, M. Skurzok, S. Wycech, A. Spallone, K. Toho, M. Tüchler, C. Yoshida, J. Zmeskal, C. Curceanu
abstract
The E2 nuclear resonance effect is a phenomenon that occurs whenthe energy of an atomic de-excitation state closely matches that of a nuclear excita-tion state, resulting in the attenuation of certain atomic X-ray lines in the resonantisotope target. The study of this effect in kaonic atoms can provide important insightinto the mechanisms of the strong kaon-nucleus interaction. In 1975, Goldfrey, Lum,and Wiegand at Lawrence Berkeley Laboratory observed the effect in9842Mo, but theydid not have enough data to reach a conclusive result. The E2 nuclear resonanceeffect is expected to occur in four kaonic molybdenum isotopes (9442Mo,9642Mo,9842Mo,and10042Mo) with similar energy values. The KAMEO (Kaonic Atoms MeasuringNuclear Resonance Effects Observables) proposal plans to study this effect in theseisotopes at the DA?NE ? factory during the SIDDHARTA-2 experiment. KAMEOwill use four solid strip targets, each enriched with a different molybdenum isotope,and expose them to negatively charged kaons produced by ? meson decays. TheX-ray transition measurements will be performed using a high-purity germaniumdetector, and an additional solid strip target of non-resonant9242Mo isotope will beexposed and used as a reference for standard non-resonant transitions.
The WASA-FRS project at GSI and its perspective
T.R. Saito, P. Achenbach, H. Alibrahim Alfaki, F. Amjad, M. Armstrong, K.-H. Behr , J. Benlliure, Z. Brencic, T. Dickel, V. Drozd, S. Dubey, H. Ekawa, S. Escrig, M. Feijoo-Fontan, H. Fujioka, Y. Gao, H. Geissel, F. Goldenbaum, A. Grana Gonzalez, E. Haettner, M.N. Harakeh, Y. He, H. Heggen, C. Hornung, N. Hubbard, K. Itahashi, M. Iwasaki, N. Kalantar-Nayestanaki, A. Kasagi, M. Kavatsyuk, E. Kazantseva, A. Khreptak, B. Kindler, R. Knoebel, H. Kollmus, D. Kostyleva, S. Kraft-Bermuth, N. Kurz, E. Liu, B. Lommel, V. Metag, S. Minami, D.J. Morrissey, P. Moskal, I. Mukha, A. Muneem, M. Nakagawa, K. Nakazawa, C. Nociforo, H.J. Ong, S. Pietri, J. Pochodzalla, S. Purushothaman, C. Rappold, E. Rocco, J.L. Rodríguez-Sanchez, P. Roy, R. Ruber, S. Schadmand, C. Scheidenberger, P. Schwarz, R. Sekiya, V. Serdyuk, M. Skurzok, B. Streicher, K. Suzuki, B. Szczepanczyk, Y.K. Tanaka, X. Tang, N. Tortorelli, M. Vencelj, H. Wang, T. Weber, H. Weick, M. Will, K. Wimmer, A. Yamamoto, A. Yanai, J. Yoshida, J. Zh
abstract
A novel technique to study bound states of exotic hadrons in subatomic nuclei, such as hypernuclei and mesic nuclei, has been developed by employing the Fragment Separator FRS and the WASA central detector at GSI. Two experiments, S447 for studying light hypernuclei, especially hypertriton and a ????nn bound state, and S490 for searching for ????? mesic-nuclei, were recently performed. Data analyses are currently in progress, and light charged particles such as protons and ????? are clearly observed and identified in the both experiments. For S447, light nuclear fragments that can also be residual nuclei from decays of hypernuclei of interests have been analysed by the FRS, and a momentum resolution, ?????????????, of 5 × 10?4 has been achieved. Further data analyses are to be completed. The WASA-FRS project will be continued and extended with the FRS at FAIR Phase 0, and upgrading of the WASA magnet and detectors is currently in progress. Furthermore, construction
of a larger detector system with the Super-FRS at FAIR Phase 1 is also under consideration.
New opportunities for kaonic atoms measurements from CdZnTe detectors
L. Abbene, M. Bettelli, A. Buttacavoli, F. Principato, A. Zappettini, C. Amsler, M. Bazzi, D. Bosnar, M. Bragadireanu, M. Cargnelli, M. Carminati, A. Clozza, G. Deda, L. De Paolis, R. Del Grande, L. Fabbietti, C. Fiorini, I. Friscic, C. Guaraldo, M. Iliescu, M. Iwasaki, A. Khreptak, S. Manti, J. Marton, M. Miliucci, P. Moskal, F. Napolitano, S. Niedźwiecki, H. Ohnishi, K. Piscicchia, Y. Sada, F. Sgaramella, H. Shi, M. Silarski, D. L. Sirghi, F. Sirghi, M. Skurzok, A. Spallone, K. Toho, M. Tuchler, O. Vazquez Doce, C. Yoshida, J. Zmeskal, A. Scordo and C. Curceanu
abstract
We present the tests performed by the SIDDHARTA-2 collaboration at the DAFNE collider with
a quasi-hemispherical CdZnTe detector. The very good room-temperature energy resolution and efficiency
in a wide energy range show that this detector technology is ideal for studying radiative transitions in
intermediate and heavy mass kaonic atoms. The CdZnTe detector was installed for the first time in an
accelerator environment to perform tests on the background rejection capabilities, which were achieved by
exploiting the SIDDHARTA-2 Luminosity Monitor. A spectrum with an 241Am source has been acquired,
with beams circulating in the main rings, and peak resolutions of 6% at 60 keV and of 2.2% at 511 keV
have been achieved. The background suppression factor, which turned out to be of the order of ~10^5?6,
opens the possibility to plan for future kaonic atom measurements with CdZnTe detectors.
Search for eta-mesic nuclei: A review of experimental and theoretical advances
A. Khreptak, M. Skurzok, P. Moskal
abstract
In the mid-1980s, theoreticians predicted possible exotic states of an eta meson and a nucleus bound by the strong interaction, so-called mesic nucleus. This led to extensive experimental efforts aimed at discovering such unstable states as well as understanding the underlying interactions via eta meson production reactions. As experiments yielded new data, more and more sophisticated theoretical models were developed to understand the fundamental eta-nucleon and eta-nucleus interactions. After more than 35 years of research in this field, several signals have been identified as possible indications of hypothetical eta-mesic nuclei, but there is still no general agreement or clear confirmation of their existence. In the paper, we review the study of the eta-mesic nuclei with an emphasis on recent research activities.
Measurements of high-n transitions in intermediate mass kaonic atoms by SIDDHARTA-2 at DAFNE
F. Sgaramella, M. Tuchler, C. Amsler, M. Bazzi, D. Bosnar, A. M. Bragadireanu, M. Cargnelli, M. Carminati, A. Clozza, G. Deda, L. De Paolis, R. Del Grande, L. Fabbietti, C. Fiorini, I. Friscic, C. Guaraldo, M. Iliescu, M. Iwasaki, A. Khreptak, S. Manti, J. Marton, M. Miliucci, P. Moskal, F. Napolitano, S. Niedźwiecki, H. Onishi, K. Piscicchia, Y. Sada, A. Scordo, M. Silarski, D. Sirghi, F. Sirghi, M. Skurzok, A. Spallone, K. Toho, O. Vazquez Doce, J. Zmeskal, E. Widmann, C. Yoshida, C. Curceanu
abstract
The SIDDHARTA-2 experiment installed at the DAFNE collider of INFN-LNF performed, for the first time,
measurements of high-n transitions in intermediate mass kaonic atoms during the data taking campaigns of 2021 and
2022. Kaonic carbon, oxygen, nitrogen and aluminium transitions, which occur in the setup materials, were measured
by using the kaons stopped in the gaseous helium target cell with aluminium frames and Kaptonwalls, and are reported in
this paper. These new kaonic atoms measurements add valuable input to the kaonic atoms transitions data base, which is
used as a reference for theories and models of the low-energy strong interaction between antikaon and nuclei. Moreover,
these results pave the way for future dedicated kaonic atoms measurements through the whole periodic table and to a new
era for the antikaon-nuclei studies at low energy.
Search for the eta mesic 3He in the pd->dppi0 reaction with the WASA-at-COSY facility
P. Adlarson, ..., E. Czerwiński, A. Khreptak, W. Krzemień, P. Moskal, O. Rundel, I. Schätti-Ozerianska, M. Skurzok, M.J. Zieliński, et al.
abstract
The excitation function for the pd -> dppi0 reaction has been measured by WASA-at-COSY experiment with the aim of searching for 3He-eta mesic nuclei. The measurement in the vicinity of eta meson production was performed using a ramped proton beam. The data analysis and interpretation was carried out with the assumption that the eta-mesic Helium decays via the formation of an intermediate N*(1535) resonance. No direct signal of the eta-mesic nucleus is observed in the excitation function. We determine a new improved upper limit for the total cross section for the bound state production and decay in the pd -> (3He-eta)bound -> dppi0 process. It varies between 13 nb to 24 nb for the bound state with width in the range Gamma (5,50) MeV.
Differential Cross Sections for Neutron-Proton Scattering in the Region of the d*(2380) Dibaryon Resonance
P. Adlarson, ..., E. Czerwiński, A. Khreptak, W. Krzemień, P. Moskal, O. Rundel, I. Schätti-Ozerianska, M. Skurzok, M.J. Zieliński, et al.
abstract
Differential cross-sections have been extracted from exclusive and kinematically complete high-statistics measurements of quasifree polarized np scattering performed in the energy region of the d*(2380) dibaryon resonance covering the range of beam energies Tn=0.98?1.29 GeV (s=2.32?2.44 GeV). The experiment was carried out with the WASA-at-COSY setup having a polarized deuteron beam impinged on the hydrogen pellet target and utilizing the quasifree process dp->np + p_spectator. In this way, the np differential cross-section sigma(theta) was measured over a large angular range. The obtained angular distributions complement the corresponding analyzing power Ay(theta) measurements published previously. A SAID partial-wave analysis incorporating the new data strengthens the finding of a resonance pole in the coupled D33-G33 waves
Three-nucleon dynamics in dp breakup collisions using the WASA detector at COSY-Jülich
P. Adlarson, ..., E. Czerwiński, A. Khreptak, W. Krzemień, P. Moskal, M. Skurzok, M.J. Zieliński, et al.
abstract
The differential cross section for the 1 H (d, pp)n breakup reaction at deuteron beam energy of 340 MeV
has been measured with the use of the WASA detector at COSY-Jülich. The set of proton-proton coincidences
registered at the Forward Detector has been analyzed on a dense grid of kinematic variables, giving in total
around 5600 data points. The cross-section data are compared to theoretical predictions based on the state-of-
the-art nucleon-nucleon potentials, combined with a three-nucleon force or the Coulomb interaction or carried
out in a relativistic regime.
Search for eta mesic 3He with the WASA-at-COSY facility in the pd-> 3He 2gamma and pd-> 3He 6gamma reactions
P. Adlarson, ..., E. Czerwiński, O. Khreptak, W. Krzemień, P. Moskal, O. Rundel, I. Schätti-Ozerianska, M. Skurzok, M.J. Zieliński, et al.
abstract
We report on the experimental search for the bound state of an eta meson and 3He nucleus performed using the WASA-at-COSY detector setup. In order to search for the eta-mesic nucleus decay, the pd->3He2gamma and pd->3He6gamma channels have been analysed. These reactions manifest the direct decay of eta meson bound in 3He nucleus. This non-mesonic decay channel has been considered for the first time. When taking into account only statistical errors, the obtained excitation functions reveal a slight indication for a possible bound state signal corresponding to an 3He-eta nucleus width Gamma above 20 MeV and binding energy Bs between 0 and 15 MeV. However, the determined cross sections are consistent with zero in the range of the systematic uncertainty. Therefore, as final result we estimate only the upper limit for the cross section of the eta-mesic 3He nucleus formation followed by the eta meson decay which varies between 2 nb and 15 nb depending on possible bound state parameters.
Search for the 3He-eta Bound State via pd -> pdpi0 Reaction
A. Khreptak, M. Skurzok, O. Rundel
abstract
We present status and perspectives of the search for the eta-mesic helium nuclei via pd -> pdpi0 reaction with the WASA-at-COSY. In this report, the experimental method is shortly described and preliminary excitation function is presented.
Examination of the Production of an Isotensor Dibaryon in the pp->pppi+pi- Reaction
P. Adlarson, ..., E. Czerwiński, O. Khreptak, W. Krzemień, P. Moskal, O. Rundel, I. Schätti-Ozerianska, M. Skurzok, M.J. Zieliński, et al.
abstract
Exclusive measurements of the quasi-free pp->pppi+pi- reaction have been performed by means of pd collisions at Tp = 1.2 GeV using the WASA detector setup at COSY. Total and differential cross sections have been obtained covering the energy region Tp=1.08-1.36 GeV (sqrt(s) = 2.35 - 2.46 GeV), which includes the regions of N*(1440) and Delta(1232)Delta(1232) resonance excitations. Calculations describing these excitations by t-channel meson exchange are at variance with experimental differential cross sections and underpredict substantially the measured total cross section. An isotensor DeltaN dibaryon resonance with I(JP)=2(1+) produced associatedly with a pion is able to overcome these deficiencies. Such a dibaryon was predicted by Dyson and Xuong and more recently calculated by Gal and Garcilazo.
Backward single-pion production in the pd->3Hepi0 reaction with WASA-at-COSY
P. Adlarson, ..., E. Czerwiński, O. Khreptak, W. Krzemień, P. Moskal, O. Rundel, I. Schätti-Ozerianska, M. Skurzok, M.J. Zieliński, et al.
abstract
New data on the production of single neutral pions in the pd->3Hepi0 reaction are presented. For fifteen proton beam momenta between pp=1.60GeV/c and pp=1.74GeV/c, differential cross sections are determined over a large fraction of the backward hemisphere. Since the only previous systematic measurements of single-pion production at these energies were made in collinear kinematics, the present work constitutes a significant extension of the current knowledge on this reaction. Even this far above the production threshold, significant changes are found in the behaviour of the angular distributions over small intervals in beam momentum.
Search for C violation in the decay eta -> pi(0)e(+)e(-) with WASA-at-COSY
R. Adlarson, WAC. Collaboration, W. Augustyniak, W. Bardan, M. Bashkanov, FS. Bergmann, M. Berlowski, A. Bondar, M. Buescher, H. Calen, I. Ciepal, H. Clement, E. Czerwinski, K. Demmich, R. Engels, A. Erven, W. Erven, W. Eyrich, R. Fedorets, K. Foehl, K. Fransson, F. Goldenbaum, A. Goswami, K. Grigoryev, CO. Gullstrom, L. Heijkenskjold, V. Hejny, N. Huesken, L. Jarczyk, T. Johansson, B. Kamys, G. Kemmerling, G. Khatri, A. Khoukaz, A. Khreptak, DA. Kirillov, S. Kistryn, H. Kleines, B. Klos, W. Krzemien, R. Kulessa, A. Kupsc, A. Kuzmin, K. Lalwani, D. Lersch, B. Lorentz, A. Magiera, R. Maier, R. Marciniewski, B. Marianski, HP. Morsch, R. Moskal, H. Ohm, W. Parol, EP. Rio, NM. Piskunov, D. Prasuhn, D. Pszczel, K. Pysz, A. Pyszniak, J. Ritman, A. Roy, Z. Rudy, O. Rundel, S. Sawant, S. Schadmand, I. Schatti-Ozerianska, et al.
abstract
We report on the search for the rare decay eta -> pi(0)e(+)e(-) which is of interest to study C violation in the electromagnetic interaction which would indicate contributions from physics beyond the Standard Model, since the allowed decay via a two-photon intermediate state is strongly suppressed. The experiment has been performed using the WASA-at-COSY installation, located at the COSY accelerator of the Forschungszentrum Julich, Germany. In total 3 x 10(7) events of the reaction pd -> He-3 eta have been recorded at an excess energy of Q = 59.8MeV. Based on this data set the C parity violating decay eta -> pi(0)gamma* -> pi(0)e(+)e(-) via a single-photon intermediate state has been searched for, resulting in new upper limits of Gamma(eta -> pi(0)e(+) e(-))/Gamma(eta -> pi(+) pi(-) pi(0)) < 3.28 x 10(-5) and Gamma(eta -> pi(0)e(+) e(-))/Gamma(eta -> all)< 7.5 x 10(-6) (CL=90%), respectively. (c) 2018 The Author. Published by Elsevier B.V.
Isotensor Dibaryon in the pp->pppi+pi- Reaction?
P. Adlarson, ..., E. Czerwiński, O. Khreptak, W. Krzemień, P. Moskal, O. Rundel, I. Schätti-Ozerianska, M. Skurzok, M.J. Zieliński, et al.
abstract
Exclusive measurements of the quasi-free pp->pppi+pi- reaction have been carried out at WASA@COSY by means of pd collisions at Tp = 1.2 GeV. Total and differential cross sections have been extracted covering the energy region Tp=1.08-1.36 GeV, which is the region of N*(1440) and Delta(1232)Delta(1232) resonance excitations. Calculations describing these excitations by t-channel meson exchange are at variance with the measured differential cross sections and underpredict substantially the experimental total cross section. An isotensor DeltaN dibaryon resonance with I(JP)=2(1+) produced associatedly with a pion is able to overcome these deficiencies.
Isotensor Dibaryon in the pp -> pp pi(+)pi(-) Reaction?
P. Adlarson, W. Augustyniak, W. Bardan, M. Bashkanov, FS. Bergmann, M. Berlowski, A. Bondar, M. Buscher, H. Calen, I. Ciepal, H. Clement, E. Czerwinski, K. Demmich, R. Engels, A. Erven, W. Erven, W. Eyrich, P. Fedorets, K. Fohl, K. Fransson, F. Goldenbaum, A. Goswami, K. Grigoryev, L. Heijkenskjold, V. Hejny, N. Husken, L. Jarczyk, T. Johansson, B. Kamys, G. Kemmerling, A. Khoukaz, O. Khreptak, DA. Kirillov, S. Kistryn, H. Kleines, B. Klos, W. Krzemien, P. Kulessa, A. Kupsc, K. Lalwani, D. Lersch, B. Lorentz, A. Magiera, R. Maier, P. Marciniewski, B. Marianski, HP. Morsch, P. Moskal, H. Ohm, W. Parol, EP. del Rio, NM. Piskunov, D. Prasuhn, D. Pszczel, K. Pysz, J. Ritman, A. Roy, Z. Rudy, O. Rundel, S. Sawant, S. Schadmand, I. Schatti-Ozerianska, T. Sefzick, V. Serdyuk, B. Shwartz, T. Skorodko, M. Skurzok, J. Smyrski, et al.
abstract
Exclusive measurements of the quasifree pp -> pp pi(+)pi(-) reaction have been carried out at WASA@ COSY by means of pd collisions at T-p = 1.2 GeV. Total and differential cross sections have been extracted covering the energy region T-p = 1.08-1.36 GeV, which is the region of N* (1440) and Delta(123)Delta(1232) resonance excitations. Calculations describing these excitations by t-channel meson exchange are at variance with the measured differential cross sections and underpredict substantially the experimental total cross section. An isotensor Delta N dibaryon resonance with I(J(P)) = 2(1(+)) produced associatedly with a pion is able to overcome these deficiencies.
Total and differential cross sections of eta-production in proton-deuteron fusion for excess energies between Q(eta)=13 MeV and Q(eta)=81 MeV
P. Adlarson, W. Augustyniak, W. Bardan, M. Bashkanov, FS. Bergmann, M. Berlowski, A. Bondar, M. Buscher, H. Calen, I. Ciepal, H. Clement, E. Czerwinski, K. Demmich, R. Engels, A. Erveno, W. Erven, W. Eyrich, P. Fedorets, K. Fohl, K. Fransson, F. Goldenbaum, A. Goswami, K. Grigoryev, CO. Gullstrom, L. Heijkenskjold, V. Hejny, N. Husken, L. Jarczyk, T. Johansson, B. Kamys, G. Kemmerling, G. Khatri, A. Khoukaz, A. Khreptak, DA. Kirillov, S. Kistryn, H. Kleines, B. Klos, W. Krzemien, P. Kulessa, A. Kupsc, A. Kuzmin, K. Lalwani, D. Lersch, B. Lorentz, A. Magiera, R. Maier, P. Marciniewski, B. Marianski, HP. Morsch, P. Moskal, H. Ohm, W. Parol, EP. del Rio, NM. Piskunovu, D. Prasuhn, D. Pszczel, K. Pysz, A. Pyszniak, J. Ritman, A. Roy, Z. Rudy, O. Rundel, S. Sawant, S. Schadmand, I. Schatti-Ozerianska, T. Sefzick, et al.
abstract
New data on both total and differential cross sections of the production of eta mesons in proton-deuteron fusion to He-3 eta in the excess energy region 13.6 MeV <= Q(eta) <= 80.9 MeV are presented. These data have been obtained with the WASA-at-COSY detector setup located at the Forschungszentrum Julich, using a proton beam at 15 different beam momenta between p(p) = 1.60 GeV/c and p(p) = 1.74 GeV/c. While significant structure of the total cross section is observed in the energy region 20 MeV less than or similar to Q(eta) less than or similar to 60 MeV, a previously reported sharp variation around Q(eta) approximate to 50 MeV cannot be confirmed. Angular distributions show the typical forward- peaking that was noted earlier. For the first time, it is possible to study the development of these angular distributions with rising excess energy over a wide interval. (c) 2018 The Author. Published by Elsevier B.V.
Total and differential cross sections of eta-production in proton-deuteron fusion for excess energies between Q_eta=13MeV and Q_eta=81MeV
P. Adlarson, ...,E. Czerwiński, A. Khreptak, W. Krzemień, P. Moskal, O. Rundel, M. Skurzok, I. Schätti-Ozerianska, M. Zieliński, et al. (WASA-at-COSY Collaboration)
abstract
New data on both total and differential cross sections of the production of eta mesons in proton-deuteron fusion to 3He-eta in the excess energy region 13.6MeV < Q < 80.9 MeV are presented. These data have been obtained with the WASA-at-COSY detector setup located at the Forschungszentrum Julich, using a proton beam at 15 different beam momenta between p_p=1.60GeV/c and p_p=1.74GeV/c. While significant structure of the total cross section is observed in the energy region 20 MeV < Q < 60MeV, a previously reported sharp variation around Q ~ 50MeV cannot be confirmed. Angular distributions show the typical forward-peaking that was reported elsewhere. For the first time, it is possible to study the development of these angular distributions with rising excess energy over a large interval.
Importance of d-wave contributions in the charge symmetry breaking reaction dd->4Hepi0
P. Adlarson, ...,E. Czerwiński, O. Khreptak, W. Krzemień, P. Moskal, O. Rundel, M. Skurzok, M. Zieliński et al. (WASA-at-COSY Collaboration)
abstract
This letter reports the first measurement of the contribution of higher partial waves in the charge symmetry breaking reaction dd->4Hepi0 using the WASA-at-COSY detector setup at an excess energy of Q=60 MeV. The determined differential cross section can be parametrized as dsigma/domega=a+bcos2theta?, where theta? is the production angle of the pion in the center-of-mass coordinate system, and the results for the parameters are a=(1.55+-0.46(stat)+0.32-0.8(syst))pb/sr and b=(13.1+-2.1(stat)+1.0-2.7(syst))pb/sr. The data are compatible with vanishing p-waves and a sizable d-wave contribution. This finding should strongly constrain the contribution of the Delta isobar to the dd->4Hepi0 reaction and is therefore crucial for a quantitative understanding of quark mass effects in nuclear production reactions.
Importance of d-wave contributions in the charge symmetry breaking reaction dd -> He-4 pi0
P. Adlarson, W. Augustyniak, W. Bardan, M. Bashkanov, FS. Bergmann, M. Berlowski, A. Bondar, M. Buscher, H. Calen, I. Ciepal, H. Clement, E. Czerwinski, K. Demmich, R. Engels, A. Erven, W. Erven, W. Eyrich, P. Fedorets, K. Fohl, K. Fransson, F. Goldenbaum, A. Goswami, K. Grigoryev, CO. Gullstrom, C. Hanhart, L. Heijkenskjold, V. Hejny, N. Husken, L. Jarczyk, T. Johansson, B. Kamys, G. Kemmerling, G. Khatri, A. Khoukaz, O. Khreptak, DA. Kirillov, S. Kistryn, H. Kleines, B. Klos, W. Krzemien, P. Kulessa, A. Kupsc, A. Kuzmin, K. Lalwani, D. Lersch, B. Lorentz, A. Magiera, R. Maier, P. Marciniewski, B. Marianski, HP. Morsch, P. Moskal, H. Ohm, W. Parol, EP. del Rio, NM. Piskunov, D. Prasuhn, D. Pszczel, K. Pysz, A. Pyszniak, J. Ritman, A. Roy, Z. Rudy, O. Rundel, S. Sawant, S. Schadmand, I. Schatti-Ozerianska, T. Sefzick, et al.
abstract
This letter reports a first quantitative analysis of the contribution of higher partial waves in the charge symmetry breaking reaction dd -> He-4 pi(0) using the WASA-at-COSY detector setup at an excess energy of Q = 60 MeV. The determined differential cross section can be parametrized as d sigma/d Omega = a + b cos(2) theta*, where theta* is the production angle of the pion in the center-of-mass coordinate system, and the results for the parameters are a = (1.55 +/- 0.46(stat)(-0.8)(+0.32)(syst)) pb/sr and b = (13.1 +/- 2.1(stat)(-2.7)(+1.0)(syst)) pb/sr. The data are compatible with vanishing p-waves and a sizable d-wave contribution. This finding should strongly constrain the contribution of the A isobar to the dd -> He-4 pi(0) reaction and is, therefore, crucial for a quantitative understanding of quark mass effects in nuclear production reactions. (C) 2018 The Author(s). Published by Elsevier B.V.
Spin dependence of eta meson production in proton-proton collisions close to threshold
P. Adlarson, ...,E. Czerwiński, O. Khreptak, W. Krzemień, P. Moskal, O. Rundel, M. Skurzok, M. Zieliński et al. (WASA-at-COSY Collaboration)
abstract
Taking advantage of the high acceptance and axial symmetry of the WASA-at-COSY detector, and
the high degree of the polarized proton beam of COSY, the reaction ~pp->pp eta has been measured
close to threshold to explore the analyzing power Ay. The angular distribution of Ay is determined
with the precision improved by more than one order of magnitude with respect to previous results
allowing a first accurate comparison with theoretical predictions. The determined analyzing power
is consistent with zero for an excess energy of Q=15 MeV signaling s wave production with no
evidence for higher partial waves. At Q=72 MeV the data reveals strong interference of Ps and
Pp partial waves and cancellation of (Pp) and Ss?Sd contributions. These results rule out the
presently available theoretical predictions for the production mechanism of the eta meson.
Spin Dependence of eta Meson Production in Proton-Proton Collisions Close to Threshold
P. Adlarson, W. Augustyniak, W. Bardan, M. Bashkanov, SD. Bass, FS. Bergmann, M. Berlowski, A. Bondar, M. Buscher, H. Calen, I. Ciepal, H. Clement, E. Czerwinski, K. Demmich, R. Engels, A. Erven, W. Erven, W. Eyrich, P. Fedorets, K. Fohl, K. Fransson, F. Goldenbaum, A. Goswami, K. Grigoryev, CO. Gullstrom, L. Heijkenskjold, V. Hejny, N. Husken, L. Jarczyk, T. Johansson, B. Kamys, G. Kemmerling, G. Khatri, A. Khoukaz, O. Khreptak, DA. Kirillov, S. Kistryn, H. Kleines, B. Klos, W. Krzemien, P. Kulessa, A. Kupsc, A. Kuzmin, K. Lalwani, D. Lersch, B. Lorentz, A. Magiera, R. Maier, P. Marciniewski, B. Marianski, HP. Morsch, P. Moskal, H. Ohm, W. Parol, EP. del Rio, NM. Piskunov, D. Prasuhn, D. Pszczel, K. Pysz, A. Pyszniak, J. Ritman, A. Roy, Z. Rudy, O. Rundel, S. Sawant, S. Schadmand, I. Schatti-Ozerianska, T. Sefzick, et al.
abstract
Taking advantage of the high acceptance and axial symmetry of the WASA-at-COSY detector, and the high polarization degree of the proton beam of COSY, the reaction (p) over right arrowp -> pp eta has been measured close to threshold to explore the analyzing power A(y). The angular distribution of A(y) is determined with the precision improved by more than 1 order of magnitude with respect to previous results, allowing a first accurate comparison with theoretical predictions. The determined analyzing power is consistent with zero for an excess energy of Q = 15 MeV, signaling s-wave production with no evidence for higher partial waves. At Q = 72 MeV the data reveal strong interference of Ps and Pp partial waves and cancellation of (Pp)(2) and Ss*Sd contributions. These results rule out the presently available theoretical predictions for the production mechanism of the eta meson.
Isoscalar single-pion production in the region of Roper and d*(2380) resonances
P. Adlarsona, W. Augustyniak, W. Bardan, M. Bashkanov, FS. Bergmann, M. Berlowski, H. Bhatt, A. Bondar, M. Buscher, H. Calen, I. Ciepal, H. Clement, E. Czerwinski, K. Demmich, R. Engels, A. Erven, W. Erven, W. Eyrich, P. Fedorets, K. Fohl, K. Fransson, F. Goldenbaum, A. Goswami, K. Grigoryev, CO. Gullstrom, L. Heijkenskjold, V. Hejny, N. Husken, L. Jarczyk, T. Johansson, B. Kamys, G. Kemmerling, G. Khatri, A. Khoukaz, O. Khreptak, DA. Kirillov, S. Kistryn, H. Kleines, B. Klos, W. Krzemien, P. Kulessa, A. Kupsc, A. Kuzmin, K. Lalwani, D. Lersch, B. Lorentz, A. Magiera, R. Maier, P. Marciniewski, B. Marianski, HP. Morsch, P. Moskal, H. Ohm, W. Parol, EP. del Rio, NM. Piskunov, D. Prasuhn, D. Pszczel, K. Pysz, A. Pyszniak, J. Ritman, A. Roy, Z. Rudy, O. Rundel, S. Sawant, S. Schadmand, I. Schatti-Ozerianska, T. Sefzick, et al.
abstract
Exclusive measurements of the quasi-free pn -> pp pi(-) and pp -> pp pi(0) reactions have been performed by means of pd collisions at T-p= 1.2 GeV using the WASA detector setup at COSY. Total and differential cross sections have been obtained covering the energy region T-p= 0.95-1.3 GeV (root s = 2.3-2.46 GeV), which includes the regions of triangle(1232), N*(1440) and d*(2380) resonance excitations. From these measurements the isoscalar single-pion production has been extracted, for which data existed so far only below T-p = 1 GeV. We observe a substantial increase of this cross section around 1 GeV, which can be related to the Roper resonance N*(1440), the strength of which shows up isolated from the triangle resonance in the isoscalar (N pi)(I=0) invariant-mass spectrum. No evidence for a decay of the dibaryon resonance d*(2380) into the isoscalar (NN pi)(I=0) channel is found. An upper limit of 180 mu b (90% CL.) corresponding to a branching ratio of 9% has been deduced. (c) 2017 The Author(s). Published by Elsevier B.V.
Search for the eta-mesic Helium in Proton-Deuteron Reaction
O. Rundel, M. Skurzok, O. Khreptak, P. Moskal
abstract
We briefly report on the search for eta-mesic helium nuclei with WASA-at-COSY detection setup. The description of the experimental method as well as the status of the data analysis of the proton?deuteron reactions are presented.
Measurement of the omega->pi+pi-pi0 Dalitz plot distribution
P. Adlarson, ..., E. Czerwiński, O. Khreptak, W. Krzemień, P. Moskal, O. Rundel, I. Schätti-Ozerianska, M. Skurzok, M.J. Zieliński, et al.
abstract
Using the production reactions pd->3Heomega and pp->pp omega, the Dalitz plot distribution for the omega->pi+pi-pi0 decay is studied with the WASA detector at COSY, based on a combined data sample of (4.408+-0.042)*10^4 events. The Dalitz plot density is parametrised by a product of the P-wave phase space and a polynomial expansion in the normalised polar Dalitz plot variables Z and phi. For the first time, a deviation from pure P-wave phase space is observed with a significance of 4.1 sigma. The deviation is parametrised by a linear term 1+2 alpha Z, with alpha determined to be +0.147+-0.036, consistent with the expectations of rho-meson-type final-state interactions of the P-wave pion pairs.
Measurement of the omega -> pi(+)pi(-)pi(0) Dalitz plot distribution The WASA-at-COSY Collaboration
P. Adlarson, W. Augustyniak, W. Bardan, M. Bashkanov, FS. Bergmann, M. Berlowski, H. Bhatt, A. Bondar, M. Buscher, H. Calen, I. Ciepal, H. Clement, E. Czerwinski, K. Demmich, R. Engels, A. Erven, W. Erven, W. Eyrich, P. Fedorets, K. Fohl, K. Fransson, F. Goldenbaum, A. Goswami, K. Grigoryev, CO. Gullstrom, L. Heijkenskjold, V. Hejny, N. Husken, L. Jarczyk, T. Johansson, B. Kamys, G. Kemmerling, FA. Khan, G. Khatri, A. Khoukaz, O. Khreptak, DA. Kirillov, S. Kistryn, H. Kleines, B. Klos, W. Krzemien, P. Kulessa, A. Kupsc, A. Kuzmin, K. Lalwani, D. Lersch, B. Lorentz, A. Magiera, R. Maier, P. Marciniewski, B. Marianski, HP. Morsch, P. Moskal, H. Ohm, EP. del Rio, NM. Piskunov, D. Prasuhn, D. Pszczel, K. Pysz, A. Pyszniak, J. Ritman, A. Roy, Z. RudyC, O. Rundel, S. Sawant, S. Schadmand, I. Schatti-Ozerianska, T. Sefzick, et al.
abstract
Using the production reactions pd -> He-3 omega and pp -> pp omega, the Dalitz plot distribution for the omega -> pi(+)pi(-)pi(0)decay is studied with the WASA detector at COSY, based on a combined data sample of (4.408 +/- 0.042) x 10(4) events. The Dalitz plot density is parametrised by a product of the P-wave phase space and a polynomial expansion in the normalised polar Dalitz plot variables Z and phi. For the first time, a deviation from pure P-wave phase space is observed with a significance of 4.1 sigma. The deviation is parametrised by a linear term 1+2 alpha Z, with alpha determined to be +0.147 +/- 0.036, consistent with the expectations of rho-meson-type final-state interactions of the P-wave pion pairs. (C) 2017 The Author. Published by Elsevier B.V.
Search for eta-mesic He-4 in the dd -> (3)Hen pi(0) and dd -> (3)Hep pi(-) reactions with the WASA-at-COSY facility
P. Adlarson, W. Augustyniak, W. Bardan, M. Bashkanov, FS. Bergmann, M. Berlowski, H. Bhatt, A. Bondar, M. Buscher, H. Calen, I. Ciepal, H. Clement, E. Czerwinski, K. Demmich, R. Engels, A. Erven, W. Erven, W. Eyrich, P. Fedorets, K. Fohl, K. Fransson, E. Goldenbaum, A. Goswami, K. Grigoryev, CO. Gullstrom, L. Heijkenskjold, V. Hejny, N. Husken, L. Jarczyk, T. Johansson, B. Kamys, NG. Kelkar, G. Kemmerling, G. Khatri, A. Khoukaz, O. Khreptak, DA. Kirillov, S. Kistryn, H. Kleines, B. Klos, W. Krzemien, P. Kulessa, A. Kupsc, A. Kuzmin, K. Lalwani, D. Lersch, B. Lorentz, A. Magierae, R. Maier, P. Marciniewski, B. Marianski, HP. Morsch, P. Moskal, H. Ohm, EP. del Rio, NM. Piskunov, D. Prasuhn, D. Pszczel, K. Pysz, A. Pyszniak, J. Ritman, A. Roy, Z. Rudy, O. Rundel, S. Sawant, S. Schadmand, I. Schatti-Ozerianska, T. Sefzick, et al.
abstract
The search for He-4-eta bound states was performed with the WASA-at-COSY facility via the measurement of the excitation function for the dd -> (3)Hen pi(0) and dd -> (3)Hep pi(-) processes. The deuteron beam momentum was varied continuously between 2.127 GeV/c and 2.422 GeV/c, corresponding to the excess energy for the dd -> He-4 eta reaction ranging from Q = 70 MeV to Q = 30 MeV. The luminosity was determined based on the dd -> (3)Hen reaction and the quasi-free proton proton scattering via dd -> ppn(spectator)n(spectator) reactions. The excitation functions, determined independently for the measured reactions, do not reveal a structure which could be interpreted as a narrow mesic nucleus. Therefore, the upper limits of the total cross sections for the bound state production and decay in dd -> (4He-eta)(bound) -> (3)Hen pi(0) and dd -> (He-4-eta)(bound) -> (3)Hep pi(-) processes were determined taking into account the isospin relation between the both of the considered channels. The results of the analysis depend on the assumptions of the N* (1535) momentum distribution in the anticipated mesic-He-4. Assuming, as in the previous works, that this is identical with the distribution of nucleons bound with 20 MeV in He-4, we determined that (for the mesic bound state width in the range from 5 MeV to 50 MeV) the upper limits at 90% confidence level are about 3 nb and about 6 nb for n pi(0) and p pi(-) channels, respectively. However, based on the recent theoretical findings of the N*(1535) momentum distribution in the N*-He-3 nucleus bound by 3.6 MeV, we find that the WASA-at-COSY detector acceptance decreases and hence the corresponding upper limits are 5 nb and 10 nb for n pi(0) and p pi(-) channels respectively. (C) 2017 Elsevier B.V. All rights reserved.
Search for eta-mesic 4He in the dd->3He n pi0 and dd->3He p pi- reactions with the WASA-at-COSY facility
P. Adlarson, ..., E. Czerwiński, O. Khreptak, W. Krzemień, P. Moskal, O. Rundel, I. Schätti-Ozerianska, M. Skurzok, M.J. Zieliński, et al.
abstract
The search for 4He-eta bound states was performed with the WASA-at-COSY facility via the measurement of the excitation function for the dd->3Henpi0 and dd->3Hepi- processes. The deuteron beam momentum was varied continuously between 2.127 GeV/c and 2.422 GeV/c, corresponding to the excess energy for the dd-> 4He eta reaction ranging from Q = -70 MeV to Q = 30 MeV. The luminosity was determined based on the dd-> 3Hen reaction and the quasi-free proton-proton scattering via dd -> ppn_spectator n_spectator reactions. The excitation functions, determined independently for the measured reactions, do not reveal a structure which could be interpreted as a narrow mesic nucleus. Therefore, the upper limits of the total cross sections for the bound state production and decay in dd->(4He-eta)bound->3Henpi0 and dd->(4He-eta)bound->3Hepi- processes were determined taking into account the isospin relation between the both of the considered channels. The results of the analysis depend on the assumptions of the N*(1535) momentum distribution in the anticipated mesic-4He. Assuming, as in the previous works, that this is identical with the distribution of nucleons bound with 20 MeV in 4He, we determined that (for the mesic bound state width in the range
from 5 MeV to 50 MeV) the upper limits at 90% confidence level are about 3 nb and about 6 nb for npi0 and p pi- channels, respectively. However, based on the recent theoretical findings of the N*(1535) momentum distribution in the N* -3He nucleus bound by 3.6 MeV, we find that the WASA-at-COSY detector acceptance decreases and hence the corresponding upper limits are 5 nb and 10 nb for n pi0 and p pi- channels respectively.
Search for an isospin I=3 dibaryon
P. Adlarson, W. Augustyniak, W. Bardan, M. Bashkanov, FS. Bergmann, M. Berlowski, H. Bhatt, A. Bondar, M. Buscher, H. Calen, I. Ciepal, H. Clement, E. Czerwinski, K. Demmich, R. Engels, A. Erven, W. Erven, W. Eyrich, P. Fedorets, K. Fohl, K. Fransson, F. Goldenbaum, A. Goswami, K. Grigoryev, CO. Gullstrom, L. Heijkenskjold, V. Hejny, N. Husken, L. Jarczyk, T. Johansson, B. Kamys, G. Kemmerling, FA. Khan, G. Khatri, A. Khoukaz, O. Khreptak, DA. Kirillov, S. Kistryn, H. Kleines, B. Klos, W. Krzemien, P. Kulessa, A. Kupsc, A. Kuzmin, K. Lalwani, D. Lersch, B. Lorentz, A. Magiera, R. Maier, P. Marciniewski, B. Marianski, HP. Morsch, P. Moskal, H. Ohm, EP. del Rio, NM. Piskunov, D. Prasuhnl, D. Pszczel, K. Pysz, A. Pyszniak, J. Ritman, A. Roy, Z. Rudy, O. Rundel, S. Sawant, S. Schadmand, I. Schatti-Ozerianska, T. Sefzick, et al.
abstract
Various theoretical calculations based on QCD or hadronic interactions predict that in addition to the recently observed dibaryon resonance d*(2380) with I(J(P)) = 3(0(+)) there should also exist a dibaryon resonance with mirrored quantum numbers I(J(P)) = 3(0(+)). We report here on a search for such a NN-decoupled state in data on the pp -> pp pi(+) pi(+) pi(-) pi(-) reaction. Since no clear-cut evidence has been found, we give upper limits for the production cross section of such a resonance in the mass range 2280-2500 MeV. (C) 2016 The Author(s). Published by Elsevier B.V.
Search for an Isospin I =3 Dibaryon
P. Adlarson, ..., E. Czerwiński, O. Khreptak, W. Krzemień, P. Moskal, O. Rundel, I. Schätti-Ozerianska, M. Skurzok, M.J. Zieliński, et al.
abstract
Various theoretical calculations based on QCD or hadronic interactions predict that in addition to the recently observed dibaryon resonance d*(2380) with I(JP)=0(3+) there should also exist a dibaryon resonance with mirrored quantum numbers I(JP)=3(0+). We report here on a search for such a NN-decoupled state in data on the pp -> pp pi+ pi+ pi- pi- reaction.
Studies of discrete symmetries in a purely leptonic system using the Jagiellonian Positron Emission Tomograph
P. Moskal, D. Alfs, T. Bednarski, P. Bialas, C. Curceanu, E. Czerwinski, K. Dulski, A. Gajos, B. Glowacz, N. Gupta-Sharma, M. Gorgol, BC. Hiesmayr, B. Jasinska, D. Kaminska, O. Khreptak, G. Korcyl, P. Kowalski, W. Krzemien, N. Krawczyk, E. Kubicz, M. Mohammed, S. Niedzwiecki, M. Pawlik-Niedzwiecka, L. Raczynski, Z. Rudy, M. Silarski, J. Smyrski, A. Wieczorek, W. Wislicki, B. Zgardzinska, M. Zielinski
abstract
Discrete symmetries such as parity (P), charge-conjugation (C) and time reversal (T) are of fundamental importance in physics and cosmology. Breaking of charge conjugation symmetry (C) and its combination with parity (CP) constitute necessary conditions for the existence of the asymmetry between matter and antimatter in the observed Universe. The presently known sources of discrete symmetries violations can account for only a tiny fraction of the excess of matter over antimatter. So far CP and T symmetries violations were observed only for systems involving quarks and they were never reported for the purely leptonic objects. In this article we describe briefly an experimental proposal for the test of discrete symmetries in the decays of positronium atom which is made exclusively of leptons. The experiments are conducted by means of the Jagiellonian Positron Emission Tomograph (J-PET) which is constructed from strips of plastic scintillators enabling registration of photons from the positronium annihilation. J-PET tomograph together with the positronium target system enable to measure expectation values for the discrete symmetries odd operators constructed from (i)spin vector of the ortho-positronium atom, (ii) momentum vectors of photons originating from the decay of positronium, and (iii) linear polarization direction of annihilation photons. Linearly polarized positronium will be produced in the highly porous aerogel or polymer targets, exploiting longitudinally polarized positrons emitted by the sodium Na-22 isotope. Information about the polarization vector of ortho-positronium will be available on the event by event basis and will be reconstructed from the known position of the positron source and the reconstructed position of the ortho-positronium annihilation. In 2016 the first tests and calibration runs are planned, and the data collection with high statistics will commence in the year 2017.
The measurement of the E2 nuclear resonance effects in kaonic atoms at DA?NE: The KAMEO proposal
L. De Paolis, L. Abbene, M. Bazzi, M. Bettelli, G. Borghi, D. Bosnar, M. Bragadireanu, A. Buttacavoli, M. Cargnelli, M. Carminati, A. Clozza, G. Deda, R. Del Grande, K. Dulski, C. Fiorini, I. Friscic, C. Guaraldo, M. Iliescu, M. Iwasaki, A. Khreptak, S. Manti, J. Marton, M. Miliucci, P. Moskal, F. Napolitano, S. Niedźwiecki, J. Obertova, O. Ohnishi, K. Piscicchia, F. Principato, Y. Sada, A. Scordo, F. Sgaramella, M. Silarski, D.L. Sirghi, F. Sirghi, M. Skurzok, S. Wycech, A. Spallone, K. Toho, M. Tüchler, C. Yoshida, A. Zappettini, J. Zmeskal, C. Curceanu
published in: EPJ Web of Conferences 291, 05003 (2024)
KAMEO (Kaonic Atoms Measuring Nuclear Resonance Effects Ob-servables) is a proposal for an experiment aiming to perform the first consistent measurement of the E2 nuclear resonance effects in kaonic molybdenum A=94,96,98,100 isotopes. The E2 nuclear resonance mixes atomic states, due to the electrical quadrupole excitation of nuclear rotational states. It occurs in atoms having the energy of a nuclear excitation state closely matching an atomic de-excitation state energy, and affects the rates of X-ray atomic transitions matching the energy of the resonance. The measurement E2 nuclear resonance effect in KMO isotopes allows the study of the strong kaon-nucleus interaction in a rotational excited nuclear state. Moreover, the effect enables the K- to access an inner atomic level not easily reachable by the kaon normal cascade, due to the nuclear absorption. The KAMEO proposed apparatus consists of 4 enriched Mo A=94,96,98,100 isotope strips, exposed to the kaons produced by the DA?NE collider, for kaonic atoms formation, with a high-purity germanium detector, cooled with liquid nitrogen, used to measure the X-ray atomic transitions. The DA?NE collider is located at the National Laboratories of Frascati (LNF-INFN), in Italy. It is already suited for kaonic atoms measurement by the SIDDHARTA-2 collaboration.
Kaonic atoms with SIDDHARTA-2 at the DA?NE collider
F. Sirghi, L. Abbene, M. Bazzi, D. Bosnar, M. Bragadireanu, A. Buttacavoli, M. Cargnelli, M. Carminati, A. Clozza, G. Deda, R. Del Grande, K. Dulski, L. De Paolis, C. Fiorini, I. Friscic, C. Guaraldo, M. Iliescu, M. Iwasaki, A. Khreptak, S. Manti, J. Marton, M. Miliucci, P. Moskal, F. Napolitano, F. Sgaramella, S. Niedźwiecki, O. Ohnishi, K. Piscicchia, Y. Sada, A. Scordo, M. Silarski, D.L. Sirghi, M. Skurzok, A. Spallone, S. Wycech, K. Toho, M. Tüchler, C. Yoshida, J. Zmeskal, C. Curceanu
published in: EPJ Web of Conferences 291, 01008 (2024)
. The most important information still missing in the field of the low-energy antikaon-nucleon interactions studies is the experimental determination of the hadronic energy shift and width of kaonic deuterium.
This measurement will be performed by the SIDDHARTA-2 experiment, installed at the DA?NE collider
and presently in data taking campaign. The precise measurement of the shift and width of the 1s level with
respect to the purely electromagnetic calculated values, generated by the presence of the strong interaction,
through the measurement of the X-ray transitions to this level, in kaonic hydrogen, was performed by the SIDDHARTA collaboration, the kaonic deuterium is underway by SIDDHARTA-2. These measurement will allow
the first precise experimental extraction of the isospin dependent antikaon-nucleon scattering lengths, fundamental quantities for understanding low-energy QCD in the strangeness sector. The experimental challenge of
the kaonic deuterium measurement is the very small X-rays yield, the even larger width (compared to kaonic hydrogen), and the difficulty to perform X-rays spectroscopy with weak signals in the high radiation environment
of DA?NE. It was, therefore, crucial to develop a new apparatus involving large-area X-rays detector system,
to optimize the signal and to control and by improve the signal-to-background ratio by gaining in solid angle,
increasing the timing capability, and as well implementing additional charge particle tracking veto systems.
Study of light hypernuclei in Europe: the hypertriton and nnLambda puzzles
C. Rappold, P. Achenbach, H. Alibrahim Alfaki, F. Amjad, M. Armstrong, K.-H. Behr, J. Benlliure, Z. Brencic, T. Dickel, V. Drozd, S. Dubey, H. Ekawa, S. Escrig, M. Feijoo-Fontan, H. Fujioka, Y. Gao, H. Geissel, F. Goldenbaum, A. Grana Gonzalez, E. Haettner, M.N. Harakeh, Y. He, H. Heggen, C. Hornung, N. Hubbard, K. Itahashi, M. Iwasaki, N. Kalantar-Nayestanaki, A. Kasagi, M. Kavatsyuk, E. Kazantseva, A. Khreptak, B. Kindler, R. Knoebel, H. Kollmus, D. Kostyleva, S. Kraft-Bermuth, N. Kurz, E. Liu, B. Lommel, V. Metag, S. Minami, D.J. Morrissey, P. Moskal, I. Mukha, A. Muneem, M. Nakagawa, K. Nakazawa, C. Nociforo, H.J. Ong, S. Pietri, J. Pochodzalla, S. Purushothaman, E. Rocco, J.L. Rodríguez-Sanchez, P. Roy, R. Ruber, T.R. Saito, S. Schadmand, C. Scheidenberger, P. Schwarz, R. Sekiya, V. Serdyuk, M. Skurzok, B. Streicher, K. Suzuki, B. Szczepanczyk, Y.K. Tanaka, X. Tang, N. Tortorelli, M. Vencelj, H. Wang, T. Weber, H. Weick, M. Will, K. Wimmer, A. Yamamoto, A. Yanai, J. Yoshida, J. Zhao
published in: EPJ Web of Conferences 290, 09007 (2023)
The current understanding of light hypernuclei, which are sub-atomic nuclei with strangeness, is being challenged and studied in detail by several European research groups and collaborations. In recent years, studies of hypernuclei using high-energy heavy ion beams have reported unexpected results on the three-body hypernuclear state 3?H, named the hypertriton. For some time, reports of a shorter lifetime and larger binding energy than what was previously accepted have created a puzzling situation for its theoretical description; this is known as the hypertriton puzzle. With the inclusion of the most recent experimental measurements, the current status of the hypertriton puzzle is evolving. Additionally, the possible neutral bound state of a ? hyperon with two neutrons, nn?, has raised questions about our understanding of the formation of light hypernuclei either in bound or resonance states. These results have initiated several ongoing experimental programs all over the world to study these three-body hypernuclear states precisely. We are studying these light hypernuclear states by employing heavy ion beams at 2AGeV on a fixed carbon target with the WASA detector system and the Fragment Separator (FRS) at GSI. The WASA-FRS experimental campaign was performed during the first quarter of 2022, and this paper presents a short overview of the campaign and how it seeks to tackle the hypertriton and nn? puzzles. Data analysis is ongoing, and several preliminary results will be reported.
SIDDHARTA-2 veto system design and performance for kaonic atoms studies at DAFNE
F. Sgaramella, M. Bazzi, D. Bosnar, M. Bragadireanu, M. Cargnelli, M. Carminati, A. Clozza, G. Deda, R. Del Grande, K. Dulski, L. De Paolis, L. Fabbietti, C. Fiorini, I. Friscic, C. Guaraldo, M. Iliescu, M. Iwasaki, A. Khreptak, S. Manti, J. Marton, M. Miliucci, P. Moskal, F. Napolitano, S. Niedźwiecki, H. Ohnishi, K. Piscicchia, Y. Sada, A. Scordo, M. Silarski, D. Sirghi, F. Sirghi, M. Skurzok, A. Spallone, K. Toho, M. Tuchler, C. Yoshida, J. Zmeskal, C. Curceanu
published in: EPJ Web Conf. 290 (2023) 06005
Light kaonic atoms spectroscopy provides a unique approach to study the low-energy strong interaction in the strangeness sector. Precise measurements of X-ray emission from light kaonic atoms provide valuable information on kaon-nucleus interaction at threshold without the need for extrapolation as required in scattering experiments. The SIDDHARTA-2 experiment at the DA?NE collider of INFN-LNF is now poised to perform the challenging measurements of the K?- d 2p -> 1s transition to extract the isospin-dependent antikaonnucleon scattering lengths. To achieve this goal, the background reduction is a crucial factor. This paper provides an overview of the SIDDHARTA-2 Veto-1 system, which uses scintillators outside the vacuum chamber to detect charged particles produced by K? absorption by the nucleus. The arrival time of these particles is correlated with the position where the kaonic atom has been created inside the setup, allowing for the rejection of kaons stopped outside the target cell, which is a critical component for reducing the background and improve the accuracy of the measurement.
Investigating the E2 Nuclear Resonance Effects in Kaonic Atoms: The KAMEO Proposal
L. De Paolis, D. Bosnar, M. Bragadireanu, M. Cargnelli, M. Carminati, A. Clozza, G. Deda, R. Del Grande, K. Dulski, C. Fiorini, I. Friscic, C. Guaraldo, M. Iliescu, M. Iwasaki, A. Khreptak, S. Manti, J. Marton, M. Miliucci, P. Moskal, F. Napolitano, S. Niedźwiecki, O. Ohnishi, K. Piscicchia, Y. Sada, A. Scordo, F. Sgaramella, M. Silarski, D.L. Sirghi, F. Sirghi, M. Skurzok, S. Wycech, A. Spallone, K. Toho, M. Tüchler, C. Yoshida, J. Zmeskal, C. Curceanu
published in: EPJ Web of Conferences 290, 06003 (2023)
The E2 nuclear resonance effect in kaonic atoms occurs when the energy of atomic de-excitation closely matches the energy of nuclear excitation, leading to the attenuation of some X-ray lines in the resonant isotope target. This phenomenon provides crucial information on the strong interaction between kaons and nuclei. The only nuclear E2 resonance effect observed so far was in the K? ?9842Mo isotope, measured by G. L. Goldfrey, G-K. Lum, and C. E. Wiegand at Lawrence Berkeley Laboratory in 1975. However, the 25 hours of data taking were not sufficient to yield conclusive results. In four kaonic Molybdenum isotopes (9442Mo, 9642Mo, 9842and Mo, and 10042Mo), the nuclear E2 resonance effect is expected to occur at the same transition with similar energy values. To investigate this, the KAMEO (Kaonic Atoms Measuring Nuclear Resonance Effects Observables) experiment plans to conduct research on kaonic Molybdenum isotopes at the DA?NE e+e? collider during the SIDDHARTA-2 experiment. The experimental strategy involves exposing four solid strip targets, each enriched with one Molybdenum isotope, to negatively charged kaons and using a germanium detector to measure X-ray transitions. In addition, a non-resonant 9242Mo isotope solid strip target will be used as a reference for standard non-resonant transitions.
Towards the first kaonic deuterium measurement with the SIDDHARTA-2 experiment
C. Curceanu, L. De Paolis, M. Bazzi, D. Bosnar, M. Bragadireanu, M. Cargnelli, M. Carminati, A. Clozza, G. Deda, K. Dulski, C. Fiorini, I. Friščić, C. Guaraldo, M. Iliescu, M. Iwasaki, A. Khreptak, P. Levi Sandri, S. Manti, J. Marton, M. Miliucci, P. Moskal, F. Napolitano, S. Niedźwiecki, H. Onishi, K. Piscicchia, Y. Sada, A. Scordo, F. Sgaramella, M. Silarski, D. L. Sirghi, F. C. Sirghi, M. Skurzok, A. Spallone, K. Toho, M. Tuchler, C. Yoshida, J. Zmeskal
published in: PoS CORFU2022 (2023) 039
The SIDDHARTA-2 experiment is presently installed at the interaction point of the DA??NE electron-positron collider of the National Laboratories of Frascati (LNF-INFN), in Italy, ready to perform the first measurement of the 2p?1s2p?1s x-ray transition in kaonic deuterium. This measurement, together with that of the kaonic hydrogen 2p?1s2p?1s x-ray transition, performed by the SIDDHARTA experiment in 2009, will allow the determination of antikaon-nucleon isospin-dependent scattering lengths. This paper presents a description of the SIDDHARTA-2 setup, which is getting ready for the kaonic deuterium measurement.
Studies of three-and four-body hypernuclei with heavy-ion beams, nuclear emulsions and machine learning
T.R. Saito, P. Achenbach, H. Alibrahim Alfaki, F. Amjad, M. Armstrong, K.-H. Behr, J. Benlliure, Z. Brencic, T. Dickel, V. Drozd, S. Dubey, H. Ekawa, S. Escrig, M. Feijoo-Fontan, Y. Gao, H. Geissel, F. Goldenbaum, A. Grana Gonzalez, E. Haettner, M. N. Harakeh, Y. He, H. Heggen, C. Hornung, N. Hubbard, K. Itahashi, N. Kalantar-Nayestanaki, A. Kasagi, M. Kavatsyuk, E. Kazantseva, A. Khreptak, R. Knoebel, H. Kollmus, D. Kostyleva, S. Kraft-Bermuth, N. Kurz, E. Liu, S. Minami, D.J. Morrissey, P. Moskal, I. Mukha, A. Muneem, M. Nakagawa, K. Nakazawa, C. Nociforo, H. J. Ong, S. Pietri, J. Pochodzalla, S. Purushothaman, C. Rappold, E. Rocco, J.L. Rodriguez-Sanchez, P. Roy, R. Ruber, N. Saito, S. Schadmand, C. Scheidenberger, P. Schwarz, R. Sekiya, V. Serdyuk, M. Skurzok, B. Streicher, S. Sugimoto, K. Suzuki, B. Szczepanczyk, M. Taki, Y.K. Tanaka, X. Tang, N. Tortorelli, M. Vencelj, H. Wang, T. Weber, H. Weick, M. Will, K. Wimmer, A. Yamamoto, A. Yanai, J. Yoshida, M. Yoshimoto, J. Zhao
published in: J. Phys.: Conf. Ser. 2586 (2023) 012148
Interests on few-body hypernuclei have been increased by recent results of experiments employing relativistic heavy ion beams. Some of the experiments have revealed that the lifetime of the lightest hypernucleus, hypertriton, is significantly shorter than 263 ps which is expected by considering the hypertriton to be a weakly-bound system. The STAR collaboration has also measured the hypertriton binding energy, and the deduced value is contradicting to its formerly known small binding energy. These measurements have indicated that the fundamental physics quantities of the hypertriton such as its lifetime and binding energy have not been understood, therefore, they have to be measured very precisely. Furthermore, an unprecedented ?nn bound state observed by the HypHI collaboration has to be studied in order to draw a conclusion whether or not such a bound state exists. These three-body hypernuclear states are studied by the heavy-ion beam data in the WASA-FRS experiment and by analysing J-PARC E07 nuclear emulsion data with machine learning.
Investigating the E2 nuclear resonance effect in kaonic atoms
L. De Paolis, M. Bazzi, D. Bosnar, M. Bragadireanu, M. Cargnelli, M. Carminati, A. Clozza, G. Deda, R. Del Grande, K. Dulski, C. Fiorini, I. Friščić, C. Guaraldo, M. Iliescu, M. Iwasaki, P. King, A. Khreptak, P. Levi Sandri, S. Manti, J. Marton, M. Miliucci, P. Moskal, F. Napolitano, S. Niedźwiecki, H. Onishi, K. Piscicchia, Y. Sada, A. Scordo, F. Sgaramella, H. Shi, M. Silarski, D. L. Sirghi. F. Sirghi, M. Skurzok, S. Wycech, A. Spallone, K. Toho, M. Tüchler, O. Vazquez Doce, C. Yoshida, J. Zmeskal and C. Curceanu
published in: J. Phys.: Conf. Ser. 2446 (2023) 012038
The nuclear E2 resonance effect occurs when an atomic de-excitation energy is closely matched by a nuclear excitation energy. It produces an attenuation of some of the atomic X-ray lines in the resonant isotope target. Investigating the nuclear E2 resonance effect in kaonic atoms, important information about kaon-nucleus strong interaction can be provided. The only ${K}^{-}{-}_{42}^{98}mathrm{Mo}$ nuclear resonance effect was measured by G. L. Goldfrey, G- K. Lum and C. E. Wiegand at Lawrence Berkeley Laboratory, in 1975. The nuclear E2 resonance effect was observed in 25 hours of data taking, not enough to provide a conclusive result. In four kaonic Molybdenum isotopes (${}_{42}^{94}mathrm{Mo}$, ${}_{42}^{96}mathrm{Mo}$, ${}_{42}^{98}mathrm{Mo}$ and ${}_{42}^{100}mathrm{Mo}$), the nuclear E2 resonance effect is expected at the same transition, with similar energy values. The KAMEO (Kaonic Atoms Measuring nuclear resonance Effects Observables) experiment plans to study the E2 nuclear resonance effect in kaonic Molybdenum isotopes at the DA?NE e+e? collider, during the SIDDHARTA-2 experiment. The experimental strategy consists of exposing four solid strip targets, each enriched with one Molybdenum isotope, to negatively charged kaons, using a germanium detector for X-ray transition measurements. A further exposure of a non-resonant ${}_{42}^{92}mathrm{Mo}$ isotope solid strip target will be used as reference for standard non-resonant transitions.
WASA-FRS Experiments in FAIR Phase-0 at GSI
Y.K. Tanaka, P. Achenbach, H. Alibrahim Alfaki, F. Amjad, M. Armstrong, K.-H. Behr, J. Benlliure, Z. Brencic, T. Dickel, V. Drozd, S. Dubey, H. Ekawa, S. Escrig, M. Feijoo-Fontán, H. Fujioka, Y. Gao, H. Geissel, F. Goldenbaum, A. Gra?a González, E. Haettner, M.N. Harakeh, Y. He, H. Heggen, C. Hornung, N. Hubbard, K. Itahashi, M. Iwasaki, N. Kalantar-Nayestanaki, A. Kasagi, M. Kavatsyuk, E. Kazantseva, A. Khreptak, B. Kindler, R. Knoebel, H. Kollmus, D. Kostyleva, S. Kraft-Bermuth, N. Kurz, E. Liu, B. Lommel, V. Metag, S. Minami, D.J. Morrissey, P. Moskal, I. Mukha, A. Muneem, M. Nakagawa, K. Nakazawa, C. Nociforo, H.J. Ong, S. Pietri, J. Pochodzalla, S. Purushothaman, C. Rappold, E. Rocco, J.L. Rodríguez-Sánchez, P. Roy, R. Ruber, T.R. Saito, S. Schadmand, C. Scheidenberger, P. Schwarz, R. Sekiya, V. Serdyuk, M. Skurzok, B. Streicher, K. Suzuki, B. Szczepanczyk, X. Tang, N. Tortorelli, M. Vencelj, H. Wang, T. Weber, H. Weick, M. Will, K. Wimmer, A. Yamamoto, A. Yanai, J. Yoshida, J. Zhao
published in: Acta. Phys. Polon. B Proc. Supp. 16 (2023) 4-A27
We have developed a new and unique experimental setup integrating the central part of the Wide Angle Shower Apparatus (WASA) into the Fragment Separator (FRS) at GSI. This combination opens up possibilities of new experiments with high-resolution spectroscopy at forward and measurements of light decay particles with nearly full solid-angle acceptance in coincidence. The first series of the WASA-FRS experiments have been successfully carried out in 2022. The developed experimental setup and two physics experiments performed in 2022 including the status of the preliminary data analysis are introduced.
Kaonic atoms measurements with SIDDHARTA-2
F. Sgaramella, M. Bazzi, D. Bosnar, M. Bragadireanu, M. Cargnelli, M. Carminati, A. Clozza, G. Deda, R. Del Grande, L. De Paolis, K. Dulski, L. Fabbietti, C. Fiorini, I. Friščić, C. Guaraldo, M. Iliescu, M. Iwasaki, A. Khreptak, S. Manti, J. Marton, M. Miliucci, P. Moskal, F. Napolitano, S. Niedźwiecki, H. Ohnishi, K. Piscicchia, Y. Sada, A. Scordo, H. Shi, M. Silarski, D. Sirghi, F. Sirghi, M .Skurzok, A. Spallone, K. Toho, M. Tüchler, C. Yoshida, J. Zmeskal, C. Curceanu
published in: J. Phys.: Conf. Ser. 2446 (2023) 012023
The SIDDHARTA-2 collaboration is aiming to perform the challenging measurement of kaonic deuterium X-ray transitions to the ground state. This will allow to extract the isospin-dependent antikaon-nucleon scattering lengths, providing input to the theory of Quantum Chromodynamics (QCD) in the non-perturbative regime with strangeness. This work describes the SIDDHARTA-2 experimental apparatus and presents the results obtained during the commissioning phase realized with kaonic helium measurements. In particular, the first observation of the kaonic helium transitions to the 3s level (M-lines), reported in this work, represents a new source of information to study the kaonic helium cascade process and demonstrates the potential of the SIDDHARTA-2 apparatus, in the view of the ambitious kaonic deuterium measurement.
The SIDDHARTA-2 experiment: preparation for the first kaonic deuterium measurement
L. De Paolis, M. Bazzi, D. Bosnar, M. Bragadireanu, M. Cargnelli, M. Carminati, A. Clozza, G. Deda, R. Del Grande, K. Dulski, C. Fiorini, I. Friščić, C. Guaraldo, M. Iliescu, M. Iwasaki, P. King, A. Khreptak, P. Levi Sandri, S. Manti, J. Marton, M. Miliucci, P. Moskal, F. Napolitano, S. Niedźwiecki, H. Onishi, K. Piscicchia, Y. Sada, A. Scordo, F. Sgaramella, H. Shi, M. Silarski, D. L. Sirghi. F. Sirghi, M. Skurzok, A. Spallone, K. Toho, M. Tüchler, C. Yoshida, J. Zmeskal and C. Curceanu
published in: PoS ICHEP2022 (2022) 1003
The SIDDHARTA-2 experiment aims to perform the first measurement of the kaonic deuterium 2p -> 1s x-ray transitions. The apparatus is presently installed at the interaction region of the DAFNE electron-positron collider at the National Laboratories of Frascati (LNF-INFN), in Italy. Kaonic deuterium and kaonic hydrogen 2p -> 1s x-ray transitions measurements, the latter one already performed by the SIDDHARTA collaboration, allow the determination of antikaon-nucleon scattering lengths. A description of the SIDDHARTA-2 apparatus in preparation for the kaonic deuterium measurement is provided in this paper.
Trigger rejection factor in the first kaonic helium run with the complete SIDDHARTA-2 setup
L. De Paolis, M. Bazzi, D. Bosnar, M. Bragadireanu, M. Cargnelli, M. Carminati, A. Clozza, G. Deda, R. Del Grande, L. Fabbietti, C. Fiorini, I. Friščić, C. Guaraldo, M. Iliescu, M. Iwasaki, A. Khreptak, P. King, P. Levi Sandri, S. Manti, J. Marton, M. Miliucci, P. Moskal, F. Napolitano, S. Niedźwiecki, H. Onishi, K. Piscicchia, Y. Sada, A. Scordo, F. Sgaramella, H. Shi, M. Silarski, D. L. Sirghi. F. Sirghi, M. Skurzok, A. Spallone, K. Toho, M. Tüchler, C. Yoshida, J. Zmeskal and C. Curceanu
published in: EPJ Web Conf. 270 (2022) 00028
The SIDDHARTA-2 experiment aims to perform the first measurement of the kaonic deuterium 2p -> 1s x-ray transition energy. Such measurement, together with the measurement of kaonic hydrogen 2p -> 1s x-ray energy transition performed by the SIDDHARTA experiment in 2011, allows the determination of kaon proton and kaon neutron scattering lengths and represents a fundamental input for the low energies QCD in the strangeness sector theory. The SIDDHARTA-2 experiment is presently installed at the DAFNE electronpositron collider at the National Laboratories of Frascati, in Italy. In May 2022, the kaonic 4He x-ray transitions measurement was performed by the complete SIDDHARTA-2 setup, by using a gaseous target. The result of this measurement is presented in this paper, with a specific focus on the background rejection performed by the kaon trigger system.
Studies of the Linearity and Stability of Silicon Drift Detectors for Kaonic Atoms X-ray Spectroscopy
A. Khreptak, C. Amsler, M. Bazzi, D. Bosnar, M. Bragadireanu, M. Cargnelli, M. Carminati, A. Clozza, G. Deda, L. De Paolis, R. Del Grande, L. Fabbietti, C. Fiorini, C. Guaraldo, M. Iliescu, M. Iwasaki, S. Manti, J. Marton, M. Miliucci, P. Moskal, F. Napolitano, S. Niedźwiecki, H. Onishi, K. Piscicchia, Y. Sada, A. Scordo, F. Sgaramella, H. Shi, M. Silarski, D. Sirghi, F. Sirghi, M. Skurzok, A. Spallone, K. Toho, M. Tüchler, O. Vazquez Doce, J. Zmeskal, C. Yoshida, C. Curceanu
published in: Acta Phys. Polon. B Proc. Suppl. 15 (2022) 4-A1
The SIDDHARTA-2 experiment at the DAFNE collider aims to perform
precision measurements of kaonic atoms X-ray spectroscopy for the
investigation of the antikaon?nucleon strong interaction. To achieve this
goal, novel large-area Silicon Drift Detectors (SDDs) have been developed.
These devices have special geometry, field configuration, and readout electronics
that ensure excellent performance in terms of linearity and stability.
The paper presents preliminary results for the linearity determination and
stability monitoring of the SDDs system during the measurement of kaonic
deuterium carried out in the summer of 2022.
Analysis of the pd->pdpi0 Reaction Measured with WASA-at-COSY Facility in Order to Search for eta-mesic Helium
A. Khreptak, M. Skurzok, O. Rundel, P. Moskal
published in: Acta Phys. Polon. B Proc. Suppl. 13 (2020) 835-840
In this report, we briefly present the preliminary results of the search for 3He-eta bound system in pd->p d pi0 reaction.
Study of Three-Nucleon Dynamics in the dp breakup collisions using the WASA detector
P. Adlarson, ..., E. Czerwiński, O. Khreptak, W. Krzemień, P. Moskal, O. Rundel, I. Schätti-Ozerianska, M. Skurzok, M.J. Zieliński, et al.
published in: Springer Proc. Phys. 238 (2020) 455
Differential cross section for the 1H(d,pp)n breakup reaction at deuteron beam energy of 340 MeV has been measured with the use of WASA detector at COSY-Juelich. The set of proton-proton coincidences registered at Forward Detector has been analysed on dense grid of kinematic variables, giving in total around 5600 data points. The cross section data are compared to theoretical predictions based on the state-of-the-art nucleon-nucleon potentials, combined with three-nucleon force, Coulomb interaction or carried out in a relativistic regime.
Search for eta-mesic 3He in non-mesonic final state
O. Rundel, M. Skurzok and A. Khreptak
published in: EPJ Web Conf. 199 (2019) 02029
The experiment on searching for eta-mesic 3He nucleus was performed in May 2014 at COSY accelerator in Juelich by WASA-at-COSY Collaboration. The measurements were carried out using ramped beam technique which allows for the slow and continuous beam momentum change near the threshold of eta meson creation. The luminosity was obtained based on pd -> 3He? reaction and quasielastic proton-proton scattering. The bound state of eta-meson and 3He nucleus is searched for in pd -> 3He2gamma and pd -> 3He6gamma channels. The analysis is still in progress and the estimated upper limit value is on the level of few nanobarns.
Luminosity determination for the proton-deutron reactions using quasi-free reactions with WASA-at-COSY facility
A. Khreptak, O. Rundel and M. Skurzok
published in: EPJ Web Conf. 199 (2019) 05026
The scientific aim of our research is experimental confirmation of the existence of mesic-nucleus: a new exotic kind of nuclear matter consisting of nucleons and mesons. In this report we present the method of luminosity determination for experiment performed atWASA-at-COSY detector dedicated to search for 3He-eta bound state. This method is based on analysis of quasi-free reaction.
Luminosity determination for the proton-deuteron reaction using pd -> 3He eta channel with WASA-at-COSY detector
M. Skurzok, O. Rundel, A. Khreptak, P. Moskal
published in: EPJ Web Conf. 181 (2018) 01014
In this report one of the methods used for the luminosity determination for the experiment performed by WASA Collaboration to search for 3He-eta mesic nuclei is presented. The method is based on the analysis of pd -> 3He eta process.
Determination of the analysing power for the vec{p} p ->pp eta reaction using WASA-at-COSY detector system
P. Adlarson, ...,E. Czerwiński, O. Khreptak, W. Krzemień, P. Moskal, O. Rundel, M. Skurzok, M. Zieliński et al. (WASA-at-COSY Collaboration)
published in: PoS BORMIO2016 (2016) 016
We report on the measurement of the analyzing power for the ~ pp -> pp eta reaction with beam
momenta of 2026 MeV/c and 2188 MeV/c performed with the WASA-at-COSY detector at the
Cooler Synchrotron COSY. The eta meson from the pp -> pp eta reaction was identified by the tech-
niques of missing mass and invariant mass. The angular distribution of the determined analyzing
power strongly disagrees with theoretical predictions. A comparison of the obtained A y angular
distribution with a series of associated Legendre polynomials revealed negligible contribution of
the Sd partial wave at Q = 15 MeV. However, at Q = 72 MeV, a significant interference of the Ps
and Pp partial waves was observed.
Studies of discrete symmetries in a purely leptonic system using the Jagiellonian Positron Emission Tomograph
P. Moskal, D. Alfs, T. Bednarski, P. Białas, C. Curceanu, E. Czerwiński, K. Dulski, A. Gajos, B. Głowacz, N. Gupta-Sharma, M. Gorgol, B. C. Hiesmayr, B. Jasińska, D. Kamińska, O. Khreptak, G. Korcyl, P. Kowalski, W. Krzemień, N. Krawczyk, E. Kubicz, M. Mohammed, Sz. Niedźwiecki, M. Pawlik-Niedźwiecka, L. Raczyński, Z. Rudy, M. Silarski, J. Smyrski, A. Wieczorek, W. Wiślicki, B. Zgardzińska, and M. Zieliński
published in: EPJ Web Conf. 130 (2016) 07015
Discrete symmetries such as parity (P), charge-conjugation (C) and time reversal (T) are of fundamental importance in physics and cosmology. Breaking of charge conjugation symmetry (C) and its combination with parity (CP) constitute necessary conditions for the existence of the asymmetry between matter and antimatter in the observed Universe. The presently known sources of discrete symmetries violations can account for only a tiny fraction of the excess of matter over antimatter. So far CP and T symmetries violations were observed only for systems involving quarks and they were never reported for the purely leptonic objects. In this article we describe briefly an experimental proposal for the test of discrete symmetries in the decays of positronium atom which is made exclusively of leptons. The experiments are conducted by means of the Jagiellonian Positron Emission Tomograph (J-PET) which is constructed from strips of plastic scintillators enabling registration of photons from the positronium annihilation. J-PET tomograph together with the positronium target system enable to measure expectation values for the discrete symmetries odd operators constructed from (i) spin vector of the ortho-positronium atom, (ii) momentum vectors of photons originating from the decay of positronium, and (iii) linear polarization direction of annihilation photons. Linearly polarized positronium will be produced in the highly porous aerogel or polymer targets, exploiting longitudinally polarized positrons emitted by the sodium 22Na isotope. Information about the polarization vector of orthopositronium will be available on the event by event basis and will be reconstructed from the known position of the positron source and the reconstructed position of the orthopositronium annihilation. In 2016 the first tests and calibration runs are planned, and the
data collection with high statistics will commence in the year 2017.
J-PET detector system for studies of the electron-positron annihilations
M. Pawlik-Niedźwiecka, O. Khreptak, A. Gajos, A. Wieczorek, D. Alfs, T. Bednarski, P. Białas, C. Curceanu, E. Czerwiński, K. Dulski, B. Głowacz, N. Gupta-Sharma, M. Gorgol, B. C. Hiesmayr, B. Jasińska, D. Kamińska, G. Korcyl, P. Kowalski, W. Krzmień, N. Krawczyk, E. Kubicz, M. Mohammed, Sz. Niedźwiecki, L. Raczyński, Z. Rudy, M. Silarski, W. Wiślicki, B. Zgardzińska, M. Zieliński, and P. Moskal
published in: EPJ Web Conf. 130 (2016) 07020
Jagiellonian Positron Emission Tomograph (J-PET) has been recently constructed at the Jagiellonian University as a prototype of a cost-effective scanner for the metabolic imaging of the whole human body. J-PET detector is optimized for the measurement of momentum and polarization of photons from the electron-positron annihilations. It is built out of strips of plastic scintillators, forming three cylindrical layers. As detector of gamma quanta it will be used for studies of discrete symmetries and multiparticle entanglement of photons originating from the decays of ortho-positronium atoms.
Searching for eta-mesic Helium with WASA-at-COSY facility
O. Rundel, O. Khreptak, M. Skurzok, W. Krzemien and P. Moskal
published in: EPJ Web Conf. 130 (2016) 02008
The search for the 4He-eta and 3He-eta bound states was performed with the WASA-at-COSY facility using a ramped beam technique in 2008, 2010 and 2014, respectively. The 2008 and 2010 data analyses has already been completed and resulted in the upper limits for the total cross sections for the eta-mesic 4He production in dd -> 3Henpi0 and dd -> 3Heppi- processes. No narrow structure which could be interpreted as a bound state was observed. The experiment carried out in 2014 collected the largest data sample for 3He-eta in the world. The data analysis is in progress. This article presents results of the 2010 data analysis and preliminary results of the 2014 data analysis.
Production and interaction of the eta meson with nucleons and nuclei
W. Krzemień, O. Khreptak, P. Moskal, I. Ozyrianska-Schaetti, O. Rundel, M. Skurzok and M. Zieliński
published in: EPJ Web Conf. 130 (2016) 03004
We report on the status of the search for eta-mesic nuclei and the studies of the interaction of the eta meson with nucleons. Recently we have completed the analysis of the new WASA-at-COSY data on the production of the eta meson with polarized proton beam. New results on the analyzing power for the p?p -> pp? reaction with more than an order of magnitude improved precision shed a new light on the production mechanism of the eta meson in nucleon-nucleon collisions. Also, the latest results of the search for eta-mesic nuclei are discussed.
