Testing CPT symmetry in ortho-positronium decays with positronium annihilation tomography
P. Moskal, A. Gajos, M. Mohammed, J. Chhokar, N. Chug, C. Curceanu, E. Czerwiński, M. Dadgar, K. Dulski, M. Gorgol, J. Goworek, B. Hiesmayr, B. Jasińska, K. Kacprzak, Ł. Kapłon, H. Karimi, D. Kisielewska, K. Klimaszewski, G. Korcyl, P. Kowalski, N. Krawczyk, W. Krzemień, T. Kozik, E. Kubicz, S. Niedźwiecki, S. Parzych, M. Pawlik-Niedźwiecka, L. Raczyński, J. Raj, S. Sharma, S. Choudhary, R. Shopa, A. Sienkiewicz, M. Silarski, M. Skurzok, E. Stepien, F. Tayefi, W. Wiślicki
abstract
Charged lepton system symmetry under combined charge, parity, and time-reversal transformation (CPT) remain scarcely tested. Despite stringent quantum-electrodynamic limits, discrepancies in predictions for the electron-positron bound state (positronium atom) motivate further investigation, including fundamental symmetry tests. While CPT noninvariance effects could be manifested in non-vanishing angular correlations between final-state photons and spin of annihilating positronium, measurements were previously limited by the knowledge of the latter. Here, we demonstrate tomographic reconstruction techniques applied to three-photon annihilations of ortho-positronium atoms to estimate their spin polarisation without a magnetic field or polarised positronium source. We use a plastic-scintillator-based positron-emission-tomography scanner to record ortho-positronium (o-Ps) annihilations with a single-event estimation of o-Ps spin and determine the complete spectrum of an angular correlation operator sensitive to CPT-violating effects. We find no violation at the precision level of 10^{-4}, with an over threefold improvement on the previous measurement.
A Simulation Study to Estimate Optimum LOR Angular Acceptance for the Image Reconstruction with the Total-Body J-PET
M. Dadgar, S. Parzych and F. Tayefi Ardebili
abstract
One of the directions in today's development of PET scanners is to increase their axial field of view (AFOV). Currently limited to several centimeters, AFOV of the clinically available PET tomographs results in a very low sensitivity (~1%) and requires an extended time for a scan of a whole human body. While these drawbacks are addressed in the so-called, Total Body PET concept (scanner with a significantly elongated field of view), it creates new challenges not only in the mechanical construction but also in image reconstruction and event selection. The possibility of taking into account of large-angle variety of lines of responses (LORs) contributes positively to the sensitivity of the tomograph. However, at the same time, the most oblique LORs have an unfavorable influence on the spatial resolution due to the parallax error and large contribution to the scatter fraction. This forces to determine a new factor -acceptance angle - which is a maximum azimuthal angle for which the LORs are still taken into image reconstruction. Correct determination of such factors is imperative to maximize the performance of a Total Body PET system since it introduces a trade-off between the two main characteristics of scanners: sensitivity and spatial resolution.
This work has been dedicated to the estimation of the optimal acceptance angle for the proposed by the Jagiellonian PET (J-PET) Collaboration Total Body tomograph. J-PET Collaboration introduces a novel, cost-effective approach to PET systems development with the use of organic scintillators. This simulation study provides evidence that the 45-degree acceptance angle cut can be an appropriate choice for the investigated scanner.
Design, structure, microstructure and gamma radiation shielding properties of refractory concrete materials containing Ba- and Sr-doped cements
D. Madej , M. Silarski , S. Parzych
abstract
This paper presents an experimental study on the performance of shielding refractory concretes containing new types of cement for use in radiation protection technology. Three concretes with corundum aggregate and special refractory inorganic cements belonging to the CaO-Al2O3, SrO-CaO-Al2O3-ZrO2, SrO-Al2O3 and BaO-CaO-Al2O3-ZrO2 systems were tested. The products formed in the hydration of these binders were detected by SEM-EDS. The linear attenuation coefficients obtained from measurements with ? quanta emitted by the following sources: 22Na, 137Cs, 60Co, 133Ba and 152Eu in the range of 80-1408 keV were determined twice,
firstly after casting and drying (110 oC) of concretes, and secondly after sintering at 1400 oC. Especially, this work fills the gap in the literature providing the gamma rays attenuation properties of cement-containing heat resistant corundum concretes in the energy region between 779 keV and 1112 keV. The experimental setup equipped with the ORTEC GMX25P4-70 High Purity Germanium detector (HPGe) cooled with liquid nitrogen was used for the determination of the gamma-ray linear attenuation coefficients of new materials. The role of the cement on the compressive and bending strengths, pore structure (mercury intrusion porosimetry), phase
composition (XRD, FT-IR), and microstructure (SEM-EDS) of heat-treated concretes was reported. It was found that the incorporation of Sr or Ba and Zr elements with cements improved the attenuation properties of corundum-based concretes, in comparison to the concretes containing Ca. The doping alkaline earth elements i.e. Sr and Ba were chemically bonded within both hydraulic matrix of green concretes and ceramic matrix formed in concrete through sintering at 1400 ?C. Hence, these materials with gamma radiation shielding capacity are designed for special construction applications.
Upper limit on the eta->pi+pi- branching fraction with the KLOE experiment
D. Babusci, M. Berlowski, C. Bloise, F. Bossi, P. Branchini, A. Budano, B. Cao, F. Ceradini, P. Ciambrone, F. Curciarello, E. Czerwiński, G. D'Agostini, E. Dan?, V. De Leo, E. De Lucia, A. De Santis, P. De Simone, A. Di Cicco, A. Di Domenico, D. Domenici, A. D'Uffizi, A. Fantini, P. Fermani, S. Fiore, A. Gajos, P. Gauzzi, S. Giovannella, E. Graziani, V. L. Ivanov, T. Johansson, X. Kang, D. Kisielewska-Kamińska, E. A. Kozyrev, W. Krzemien, A. Kupsc, P. A. Lukin, G. Mandaglio, M. Martini, R. Messi, S. Miscetti, D. Moricciani, P. Moskal, S. Parzych, A. Passeri, V. Patera, E. Perez del Rio, P. Santangelo, M. Schioppa, A. Selce, M. Silarski, F. Sirghi, E. P. Solodov, L. Tortora, G. Venanzoni, W. Wiślicki, M. Wolke
abstract
Based on an integrated luminosity of 1.61 fb^{-1} e+e- collision data collected with the KLOE detector at DAFNE, the Frascati phi-factory, a search for the P- and CP-violating decay eta->pi+pi- has been performed. Radiative phi->eta gamma decay is exploited to access the eta mesons. No signal is observed in the pi+pi- invariant mass spectrum, and the upper limit on the branching fraction at 90% confidence level is determined to be B(eta->pi+pi-)<4.9x10^{-6}, which is approximately three times smaller than the previous KLOE result. From the combination of these two measurements we get B(eta->pi+pi-)<4.4x10^{-6} at 90% confidence level.
Measurement of the branching fraction for the decay KS -> pi mu nu with the KLOE detector
D. Babusci, M. Berlowski, C. Bloise, F. Bossi, P. Branchini, A. Budano, B. Cao, F. Ceradini, P. Ciambrone, F. Curciarello, E. Czerwisnski, G. D'Agostini, E. Dane, V. De Leo, E. De Lucia, A. De Santis, P. De Simone, A. Di Cicco, A. Di Domenico, D. Domenici, A. D'Uffizi, A. Fantini, P. Fermani, S. Fiore, A. Gajos, P. Gauzzi, S. Giovannella, E. Graziani, V. L. Ivanov, T. Johansson, X. Kang, D. Kisielewska-Kamisnska, E. A. Kozyrev, W. Krzemien, A. Kupsc, P. A. Lukin, G. Mandaglio, M. Martini, R. Messi, S. Miscetti, D. Moricciani, P. Moskal, S. Parzych, A. Passeri, V. Patera, E. Perez del Rio, P. Santangelo, M. Schioppa, A. Selce, M. Silarski, F. Sirghi, E. P. Solodov, L. Tortora, G. Venanzoni, W. Wislicki, M. Wolke
abstract
Based on a sample of 300 million KS mesons produced in phi -> KLKS decays recorded by the KLOE experiment at the DAFNE e+e- collider we have measured the branching fraction for the decay KS -> pi mu nu. The KS mesons are identified by the interaction of KL mesons in the detector. The KS -> pi mu nu decays are selected by a boosted decision tree built with kinematic variables and by a time-of-flight measurement. Signal efficiencies are evaluated with data control samples of KL -> pi mu nu decays. A fit to the reconstructed muon mass distribution finds 7223?180 signal events. Normalising to the KS -> pi+ pi- decay events the result for the branching fraction is B(KS -> pi mu nu) = (4.56+-0.11stat+-0.17syst)×10-4.
Application of multivariate analysis in search of the Ks->3pi0 decay in the KLOE experiment
S. Parzych
abstract
According to the Standard Model, one of the purely CP-violating processes is the never observed KS->3pi0 decay. The best upper limit on the branching ratio of this process BR(KS->3p0)<2.6×10^-8 was obtained in the KLOE experiment using cut-based analysis. In this paper, we show preliminary results of an alternative approach to those studies using multivariate analysis methods.
Introduction of the DOI capable Total-Body J-PET, a simulation study
Meysam Dadgar, Szymon Parzych, Faranak Tayefi Ardebili, Paweł Moskal and Stefaan Vandenberghe
published in: The Journal of Nuclear Medicine 2022, 63 (supplement 2) 3316;
Introduction of the DOI capable Total-Body J-PET, a simulation study
Meysam Dadgar , Szymon Parzych , Faranak Tayefi , Paweł Moskal , Stefaan Vandenberghe
published in: The Journal of Nuclear Medicine
From tests of discrete symmetries to medical imaging with J-PET detector
P. Moskal, J. Baran, N. Chug, C. Curceanu, E. Czerwiński, M. Dadgar, K. Dulski, J. Gajewski, A. Gajos, M. Gorgol, B.C. Hiesmayr, B. Jasińska, K. Kacprzak, Ł. Kapłon, H. Karimi, K. Klimaszewski, P. Konieczka, G. Korcyl, T. Kozik, N. Krawczyk, W. Krzemień, E. Kubicz, D. Kumar, S. Niedźwiecki, D. Panek, S. Parzych, E. Perez del Rio, L. Raczyński, J. Raj, A. Ruciński, S. Sharma, Shivani, R.Y. Shopa, M. Silarski, M. Skurzok, E.Ł. Stępień, M. Szczepanek, F. Tayefi, W. Wiślicki
published in: PoS PANIC2021 (2022) 033
We present results on CPT symmetry tests in decays of positronium performed with the precision at the level of 10?4, and positronium images determined with the prototype of the J-PET tomograph. The first full-scale prototype apparatus consists of 192 plastic scintillator strips readout from both ends with vacuum tube photomultipliers. Signals produced by photomultipliers are probed in the amplitude domain and are digitized by FPGA-based readout boards in triggerless mode. In this contribution we report on the first two- and three-photon positronium images and tests of CPT symmetry in positronium decays.
A simulation based study to introduce small animal Total-Body PET by J-PET technology
M. Dadgar , F. Tayefi Ardebili, S. Parzych, E. Stepien and P. Moskal
IEEE TRANSACTIONS ON NUCLEAR SCIENCE
