Near-threshold charged kaon pair production in two protons collisions
D. Gil, J. Smyrski
abstract
The pp -> ppK(+)K(-) reaction was measured near threshold at excess energy Q = 4.5 MeV using the COSY-11 detection system installed at the COSY-Juelich accelerator. Preliminary value of upper limit of the total cross section was determined. This limit indicates that an enhancement of the total cross section close to the threshold, caused by the final state interaction, is smaller than suggested by extrapolation of data measured at higher energies.
Determination of the total width of the eta-prime meson
E. Czerwiński, P. Moskal, D. Grzonka, R. Czyżykiewicz, D. Gil, B. Kamys, A. Khoukaz, J. Klaja, P. Klaja, W. Krzemień, W. Oelert, J. Ritman, T. Sefzick, M. Siemaszko, M. Silarski, J. Smyrski, A. Täschner, M. Wolke, P. Wüstner, J. Zdebik, M. Zieliński, W. Zipper
abstract
Taking advantage of both the low-emittance proton beam of the cooler synchrotron COSY and the high momentum precision of the COSY-11 detector system, the mass distribution of the eta-prime meson was measured with a resolution of 0.33??MeV/c2 (FWHM), improving the experimental mass resolution by almost an order of magnitude with respect to previous results. Based on the sample of more than 2300 reconstructed pp->pp eta-prime events, the total width of the eta-prime meson was determined to be Gamma(eta-prime) = 0.226+-0.017(stat)+-0.014(syst)??MeV/c2.
Two-proton correlation function for the pp -> pp + eta and pp to pp + pions reactions
P. Klaja, P. Moskal, E. Czerwiński, R. Czyżykiewicz, A. Deloff, D. Gil, D. Grzonka, B. Kamys, A. Khoukaz, J. Klaja, W. Krzemień, W. Oelert, J. Ritman, T. Sefzick, M. Siemaszko, M. Silarski, J. Smyrski, A. Täschner, M. Wolke, J. Zdebik, M. Zieliński, W. Zipper
abstract
For the very first time, the correlation femtoscopy method is applied to a kinematically complete measurement of meson production in the collisions of hadrons. A two-proton correlation function was derived from the data for the pp -> ppX reaction, measured near the threshold of eta meson production. A technique developed for the purpose of this analysis permitted the correlation function to be established separately for the production of the pp + eta and of the pp + pions systems. The shape of the two-proton correlation function for pp-eta differs from that for pp(pions) and both do not show a peak structure, opposite to the results determined for inclusive measurements of heavy ion collisions.
Two-proton correlation function for the pp -> pp plus eta and pp -> pp plus pions reactions
P. Klaja, P. Moskal, E. Czerwinski, R. Czyzykiewicz, A. Deloff, D. Gil, D. Grzonka, B. Kamys, A. Khoukaz, J. Klaja, W. Krzemien, W. Oelert, J. Ritman, T. Sefzick, M. Siemaszko, M. Silarski, J. Smyrski, A. Taschner, M. Wolke, J. Zdebik, M. Zielinski, W. Zipper
abstract
For the very first time, the correlation femtoscopy method is applied to a kinematically complete measurement of meson production in the collisions of hadrons. A two-proton correlation function was derived from the data for the pp -> ppX reaction, measured near the threshold of eta meson production. A technique developed for the purpose of this analysis permitted the correlation function to be established separately for the production of the pp + eta and of the pp + pions systems. The shape of the two-proton correlation function for pp eta differs from that for pp(pions) and both do not show a peak structure, opposite to the results determined for inclusive measurements of heavy ion collisions.
Upper limit of the total cross section for the pn->pn eta-prime reaction
J. Klaja, P. Moskal, S. D. Bass, E. Czerwiński, R. Czyżykiewicz, D. Gil, D. Grzonka, T. Johansson, B. Kamys, A. Khoukaz, P. Klaja, W. Krzemień, W. Oelert, B. Rejdych, J. Ritman, T. Sefzick, M. Siemaszko, M. Silarski, J. Smyrski, A. Täschner, M. Wolke, P. Wüstner, J. Zdebik, M. Zieliński, W. Zipper
abstract
The upper limit of the total cross section for the pn->pneta-prime reaction has been determined near the kinematical threshold in the excess energy range from 0 to 24 MeV. The measurement was performed using the COSY-11 detector setup, a deuteron cluster target, and the proton beam of COSY with a momentum of 3.35 GeV/c. The energy dependence of the upper limit of the cross section was extracted exploiting the Fermi momenta of nucleons inside the deuteron. Comparison of the determined upper limit of the ratio R(eta-prime)=sigma(pn->pneta-prime)/sigma(pp->ppeta-prime) with the corresponding ratio for eta-meson production does not favor the dominance of the N*(1535) resonance in the production process of the eta-prime meson and suggests nonidentical production mechanisms for eta and eta-prime mesons.
Measurement of the invariant mass distributions fot he pp->pp eta-prime reaction at excess energy of Q = 16.4 MeV
P. Klaja, P. Moskal, E. Czerwiński, R. Czyżykiewicz, A. Deloff, D. Gil, D. Grzonka, L. Jarczyk, B. Kamys, A. Khoukaz, J. Klaja, K. Nakayama, W. Oelert, J. Ritman, T. Sefzick, M. Siemaszko, M. Silarski, J. Smyrski, A. Täschner, M. Wolke, J. Zdebik, M. Zieliński, W. Zipper
abstract
The proton?proton and proton? invariant mass distributions have been determined for the reaction at an excess energy of . The measurement was carried out using the COSY-11 detector setup and the proton beam of the cooler synchrotron COSY. The shapes of the determined invariant mass distributions are similar to those of the reaction and reveal an enhancement for large relative proton?proton momenta. This result, together with the fact that the proton?? interaction is much stronger that the proton? interaction, excludes the hypothesis that the observed enhancement is caused by the interaction between the proton and the meson.
Upper limit of the total cross section for the pn -> pn eta' reaction
J. Klaja, P. Moskal, SD. Bass, E. Czerwinski, R. Czyzykiewicz, D. Gil, D. Grzonka, T. Johansson, B. Kamys, A. Khoukaz, P. Klaja, W. Krzemien, W. Oelert, B. Rejdych, J. Ritman, T. Sefzick, M. Siemaszko, M. Silarski, J. Smyrski, A. Taschner, M. Wolke, P. Wustner, J. Zdebik, M. Zielinski, W. Zipper
abstract
The upper limit of the total cross section for the pn -> pn eta' reaction has been determined near the kinematical threshold in the excess energy range from 0 to 24 MeV. The measurement was performed using the COSY-11 detector setup, a deuteron cluster target, and the proton beam of COSY with a momentum of 3.35 GeV/c. The energy dependence of the upper limit of the cross section was extracted exploiting the Fermi momenta of nucleons inside the deuteron. Comparison of the determined upper limit of the ratio R-eta' = sigma(pn -> pn eta')/sigma(pp -> pp eta') with the corresponding ratio for eta-meson production does not favor the dominance of the N*(1535) resonance in the production process of the eta' meson and suggests nonidentical production mechanisms for eta and eta' mesons.
Measurement of the invariant mass distributions for the pp -> pp eta ' reaction at excess energy of Q=16.4 MeV
P. Klaja, P. Moskal, E. Czerwinski, R. Czyzykiewicz, A. Deloff, D. Gil, D. Grzonka, L. Jarczyk, B. Kamys, A. Khoukaz, J. Klaja, K. Nakayama, W. Oelert, J. Ritman, T. Sefzick, M. Siemaszko, M. Silarski, J. Smyrski, A. Taschner, M. Wolke, J. Zdebik, M. Zielinski, W. Zipper
abstract
The proton-proton and proton-eta' invariant mass distributions have been determined for the pp -> pp eta' reaction at an excess energy of Q = 16.4 MeV. The measurement was carried Out using the COSY-11 detector setup and the proton beam of the cooler synchrotron COSY. The shapes of the determined invariant mass distributions are similar to those of the pp -> pp eta reaction and reveal an enhancement for large relative proton-proton momenta. This result, together with the fact that the proton-eta interaction is Much stronger that the proton-eta' interaction, excludes the hypothesis that the observed enhancement is caused by the interaction between the proton and the meson. (C) 2010 Elsevier B.V. All rights reserved.
Invariant-mass distributions for the pp -> pp eta reaction at Q=10 MeV
P. Moskal, R. Czyzykiewicz, E. Czerwinski, D. Gil, D. Grzonka, L. Jarczyk, B. Kamys, A. Khoukaz, J. Klaja, P. Klaja, W. Krzemien, W. Oelert, J. Ritman, T. Sefzick, M. Siemaszko, M. Silarski, J. Smyrski, A. Taschner, M. Wolke, P. Wustner, J. Zdebik, MJ. Zielinski, W. Zipper
abstract
Proton-proton and proton-eta invariant-mass distributions and the total cross-section for the pp -> pp eta reaction have been determined near the threshold at an excess energy of Q = 10 MeV. The experiment has been conducted using the COSY-11 detector setup and the cooler synchrotron COSY. The determined invariant-mass spectra reveal significant enhancements in the region of low proton-proton relative momenta, similarly as observed previously at higher excess energies of Q = 15.5 MeV and Q = 40 MeV.
Invariant mass distributions for the pp->pp eta reaction at Q = 10 MeV
P. Moskal, R. Czyżykiewicz, E. Czerwiński, D. Gil, D. Grzonka, L. Jarczyk, B. Kamys, A. Khoukaz, J. Klaja, P. Klaja, W. Krzemień, W. Oelert, J. Ritman, T. Sefzick, M. Siemaszko, M. Silarski, J. Smyrski, A. Taschner, M. Wolke, P. Wustner, J. Zdebik, M. Zieliński, W. Zipper
abstract
Proton-proton and proton-eta invariant-mass distributions and the total cross-section for the pp -> pp h reaction have been determined near the threshold at an excess energy of Q = 10 MeV. The experiment has been conducted using the COSY-11 detector setup and the cooler synchrotron COSY. The determined invariant-mass spectra reveal significant enhancements in the region of low proton-proton relative momenta, similarly as observed previously at higher excess energies of Q = 15.5 MeV and Q = 40 MeV.
Generalized Dalitz plot analysis of the near-threshold pp -> ppK(+)K(-) reaction in view of the K+K- final state interaction
M. Silarski, P. Moskal, E. Czerwinski, R. Czyzykiewicz, D. Gil, D. Grzonka, L. Jarczyk, B. Kamys, A. Khoukaz, J. Klaja, P. Klaja, W. Krzemien, W. Oelert, J. Ritman, T. Sefzick, M. Siemaszko, J. Smyrski, A. Taschner, P. Winter, M. Wolke, P. Wustner, M. Zielinski, W. Zipper, J. Zdebik
abstract
The excitation function for the pp -> ppK(+)K(-) reaction revealed a significant enhancement close to threshold that may plausibly be assigned to the influence of the pK(-) and K+K- final-state interactions. In an improved reanalysis of COSY-11 data for the pp -> ppK(+)K(-) reaction at excess energies of Q = 10 and 28 MeV, including the proton-K- interaction, the enhancement is confirmed. Invariant mass distributions for the two- and three-particle subsystems allow us to test at low excess energies the ansatz and parameters for the description of the interaction in the ppK(+)K(-) system as derived from the COSY-ANKE data. Finally, based for the first time on the low-energy K+K- invariant mass distributions and the generalized Dalitz plot analysis, we estimate the scattering length for the K+K- interaction to be vertical bar Re(a(K+K-))vertical bar = 0.5(-0.5)(+4.0) fm and Im(a(K+K-)) = 3.0 +/- 3.0 fm.
Generalized Dalitz plot analysis of the near-threshold pp->ppK+K- reaction in view of the K+K- final state interaction
M. Silarski, P. Moskal, E. Czerwiński, R. Czyżykiewicz, D. Gil, D. Grzonka, L. Jarczyk, B. Kamys, A. Khoukaz, J. Klaja, P. Klaja, W. Krzemień, W. Oelert, J. Ritman, T. Sefzick, M. Siemaszko, J. Smyrski, A. Täschner, P. Winter, M. Wolke, P. Wüstner, M. Zieliński, W. Zipper, J. Zdebik
abstract
The excitation function for the pp->ppK+K- reaction revealed a significant enhancement close to threshold which may plausibly be assigned to the influence of the pK- and K+K- final state interactions. In an improved reanalysis of COSY-11 data for the pp-> ppK+K- reaction at excess energies of Q = 10 MeV and 28 MeV including the proton-K- interaction the enhancement is confirmed. Invariant mass distributions for the two- and three-particle subsystems allow to test at low excess energies the ansatz and parameters for the description of the interaction in the ppK+K- system as derived from the COSY-ANKE data. Finally, based for the first time on the low energy K+K- invariant mass distributions and the generalized Dalitz plot analysis, we estimate the scattering length for the K+K- interaction to be |Re(a_K+K-)| = 0.5 + 4.0 -0.5 fm and Im(a_K+K-) = 3.0 +- 3.0 fm.
Measurement of the eta -> 3 pi(0) Dalitz plot distribution with the WASA detector at COSY
C. Adolph, M. Angelstein, M. Bashkanov, U. Bechstedt, S. Belostotski, M. Berlowski, H. Bhatt, J. Bisplinghoff, A. Bondar, B. Borasoy, M. Buscher, H. Calen, K. Chandwani, H. Clement, E. Czerwinski, R. Czyzykiewicz, G. D'Orsaneo, D. Duniec, C. Ekstrom, R. Engels, W. Erven, W. Eyrich, P. Fedorets, O. Felden, K. Fransson, D. Gil, F. Goldenbaum, K. Grigoryev, A. Heczko, C. Hanhart, V. Hejny, F. Hinterberger, M. Hodana, B. Hoistad, A. Izotov, M. Jacewicz, M. Janusz, BR. Jany, L. Jarczyk, T. Johansson, B. Kamys, G. Kemmerling, I. Keshelashvili, O. Khakimova, A. Khoukaz, K. Kilian, N. Kimura, S. Kistryn, J. Klaja, P. Klaja, H. Kleines, B. Klos, A. Kowalczyk, F. Kren, W. Krzemien, P. Kulessa, S. Kullander, A. Kupsc, A. Kuzmin, V. Kyryanchuk, J. Majewski, H. Machner, A. Magiera, R. Maier, R. Marciniewski, W. Migdal, UG. Meissner, et al.
abstract
In the first production run of the WASA experiment at COSY, the eta decay into three neutral pions was measured in proton-proton interactions at a proton beam kinetic energy of 1.4 GeV. The Dalitz plot of the three pious was Studied using 1.2 x 10(5) fully reconstructed events. and the quadratic slope parameter alpha was determined to be -0.027 +/- 0.008(stat) +/- 0.005(syst). The result is consistent with previous measurements and further corroborates the importance of pion-pion final state interactions. (C) 2009 Elsevier B.V. All rights reserved.
Near-threshold production of the eta meson via the quasi-free pn->pneta reaction
P. Moskal, R. Czyżykiewicz, H.-H. Adam, S. D. Bass, A. Budzanowski, E. Czerwiński, D. Gil, D. Grzonka, M. Janusz, L. Jarczyk, T. Johansson, B. Kamys, A. Khoukaz, K. Kilian, P. Klaja, J. Majewski, W. Oelert, C. Piskor-Ignatowicz, J. Przerwa, B. Rejdych, J. Ritman, T. Rozek, T. Sefzick, M. Siemaszko, M. Silarski, J. Smyrski, A. Taeschner, M. Wolke, P. Wuestner, M. Zieliński, W. Zipper, J. Zdebik
abstract
Total cross sections for the quasifree pn->pn? reaction in the range from the kinematical threshold up to 20 MeV excess energy have been determined. At threshold they exceed corresponding cross sections for the pp?pp? reaction by a factor of about 3 in contrast to the factor of 6 established for higher excess energies. To large extent, the observed decrease of the ratio sigma(pn->pn?)/sigma(pp->pp?) toward threshold may be assigned to the different energy dependence of the proton-proton and proton-neutron final-state interactions. The experiment was conducted using a proton beam of the cooler synchrotron COSY and a cluster jet deuteron target. The proton-neutron reactions were tagged by the spectator proton whose momentum was measured for each event. Protons and neutron outgoing from the pn?pn? reaction have been registered by means of the COSY-11 facility, an apparatus dedicated for threshold meson production.
Isospin dependence of the eta-prime meson production in nucleon-nucleon collisions
J. Przerwa, P. Moskal, A. Budzanowski, E. Czerwiński, R. Czyżykiewicz, D. Gil, D. Grzonka, L. Jarczyk, T. Johansson, B. Kamys, A. Khoukaz, P. Klaja, W. Krzemień, W. Oelert, C. Piskor-Ignatowicz, J. Ritman, B. Rejdych, T. Sefzick, M. Siemaszko, M. Silarski, J. Smyrski, A. Taschner, M. Wolke, P. Wustner, J. Zdebik, M. Zieliński, W. Zipper
abstract
A comparison of the close-to-threshold total cross section for the eta prime production in pp -> pp eta prime and pn -> pn eta prime reactions constitutes a tool to investigate the eta prime meson structure and the reaction mechanism in the channels of isospin I=0 and I=1 and may provide insight into the flavour-singlet (perhaps also into gluonium) content of the eta prime meson. In this contribution we present preliminary results of measurement of the quasi-free production of the eta prime meson in the proton-neutron collisions conducted using the COSY-11 facility.
ISOSPIN DEPENDENCE OF THE eta ' MESON PRODUCTION IN NUCLEON-NUCLEON COLLISIONS
J. Przerwa, P. Moskal, A. Budzanowski, E. Czerwinski, R. Czyzykiewicz, D. Gil, D. Grzonka, L. Jarczyk, T. Johansson, B. Kamys, A. Khoukaz, P. Klaja, W. Krzemien, W. Oelert, C. Piskor-Ignatowicz, J. Ritman, B. Rejdych, T. Sefzick, M. Siemaszko, M. Silarski, J. Smyrski, A. Taschner, M. Wolke, P. Wustner, J. Zdebik, MJ. Zielinski, W. Zipper
abstract
A comparison of the close-to-threshold total cross section for the eta' production in pp -> pp eta' and pn -> pn eta' reactions constitutes a tool to investigate the eta' meson structure and the reaction mechanism in the channels of isospin I = 0 and I = 1 and may provide insight into the flavour-singlet (perhaps also into gluonium) content of the eta' meson. In this contribution we present preliminary results of measurement of the quasifree production of the eta' meson in the proton-neutron collisions conducted using the COSY-11 facility.
SEARCH FOR THE He-3-eta BOUND STATE AT COSY-11
W. Krzemien, J. Smyrski, A. Budzanowski, E. Czerwinski, R. Czyzykiewicz, D. Gil, D. Grzonka, L. Jarczyk, B. Kamys, A. Khoukaz, P. Klaja, P. Moskal, W. Oelert, J. Przerwa, J. Ritman, T. Sefzick, M. Siemaszko, M. Silarski, A. Taschner, M. Wolke, P. Wustner, J. Zdebik, MJ. Zielinski, W. Zipper
abstract
We have measured excitation function for dp -> ppp pi(-) reaction near the. production threshold. We observe an enhancement of the counting rate above the threshold which can originate from the production of the. meson in the reaction dp -> He-3 eta and its subsequent absorption on neutron in the 3He nucleus leading to creation of the p pi(-) pair.
Search for the 3He-eta bound state at COSY-11
W. Krzemien, J. Smyrski, A. Budzanowski, E. Czerwiński, R. Czyżykiewicz, D. Gil, D. Grzonka, L. Jarczyk, B. Kamys, A. Khoukaz, P. Klaja, P. Moskal, W. Oelert, J. Przerwa, J. Ritman, T. Sefzick, M. Siemaszko, M. Silarski, A. Taeschner, M. Wolke, P. Wuestner, J. Zdebik, M. Zieliński, W. Zipper
abstract
We have measured excitation function for dp -> ppp_pi- reaction near the eta production threshold. We observe an enhancement of the counting rate above the threshold which can originate from the production of the eta meson in the reaction dp -> 3He eta and its subsequent absorption on neutron in the 3He nucleus leading to creation of the p_pi- pair.
Near-threshold production of the eta meson via the quasifree pn -> pn eta reaction
P. Moskal, R. Czyzykiewicz, HH. Adam, SD. Bass, A. Budzanowski, E. Czerwinski, D. Gil, D. Grzonka, M. Janusz, L. Jarczyk, T. Johansson, B. Kamys, A. Khoukaz, K. Kilian, P. Klaja, J. Majewski, W. Oelert, C. Piskor-Ignatowicz, J. Przerwa, B. Rejdych, J. Ritman, T. Rozek, T. Sefzick, M. Siemaszko, M. Silarski, J. Smyrski, A. Taschner, M. Wolke, P. Wustner, M. Zielinski, W. Zipper, J. Zdebik
abstract
Total cross sections for the quasifree pn -> pn eta reaction in the range from the kinematical threshold up to 20 MeV excess energy have been determined. At threshold they exceed corresponding cross sections for the pn -> pn eta reaction by a factor of about 3 in contrast to the factor of 6 established for higher excess energies. To large extent, the observed decrease of the ratio s(pn -> pn eta)/s=sigma(pn -> pn eta) toward threshold may be assigned to the different energy dependence of the proton-proton and proton-neutron final-state interactions. The experiment was conducted using a proton beam of the cooler synchrotron COSY and a cluster jet deuteron target. The proton- neutron reactions were tagged by the spectator proton whose momentum was measured for each event. Protons and neutron outgoing from the pn -> pn eta reaction have been registered by means of the COSY-11 facility, an apparatus dedicated for threshold meson production.
Study of the hadronic production of kaon pairs below the threshold for the phi meson
P. Moskal, M. Silarski, A. Budzanowski, E. Czerwinski, R. Czyzykiewic, D. Gil, D. Grzonka, M. Janusz, L. Jarczyk, B. Kamys, A. Khoukaz, P. Klaja, W. Oelert, C. Piskor-Ignatowicz, J. Przerwa, B. Rejdych, J. Ritman, T. Sefzick, M. Siemaszko, J. Smyrski, A. Taschner, P. Winter, M. Wolke, P. Wustner, MJ. Zielinski, W. Zipper, J. Zdebik
abstract
The near threshold production of K(+)K(-) pairs in proton-proton collisions has been investigated at the cooler synchrotron COSY below and above the threshold for the phi meson using the COSY-11 and ANKE facilities., respectively. The excitation function determined for the pp -> ppK(+)K(-) reaction revealed a statistically significant enhancement close to the threshold which may plausibly be assigned to the influence of the K(-)p interaction. In addition, observed consistently by both groups, a strong enhancement at low values of the ratio of the K(-)p to K(+)p invariant mass distributions shows that the proton interacts much stronger with K(-) than with K(+). In this report we focus on the measurements performed by the COSY-11 collaboration. We explain the experimental method used and present main results of completed analyses as well as a new qualitative elaboration of the ppK(+)K(-) events population on the Goldhaber plot. We conclude with the observation that event densities increase at the region where the influence from the K(+)K(-) interaction is expected.
Near threshold production of the pseudoscalar mesons at the COSY-11 facility
P. Moskal, R. Czyzykiewicz, HH. Adam, A. Budzanowski, E. Czerwinski, D. Gil, D. Grzonka, M. Janusz, L. Jarczyk, B. Kamys, A. Khoukaz, X. Kilian, P. Klaja, W. Oelert, C. Piskor-Ignatowicz, J. Przerwa, B. Rejdych, J. Ritman, T. Sefzick, M. Siemaszko, M. Silarski, J. Smyrski, A. Taschner, M. Wolke, P. Winter, P. Wustner, M. Zielinski, W. Zipper
abstract
We summarise measurements of the COSY-11 collaboration concerning the excitation functions of the near threshold pseudoscalar meson production in the proton-proton interaction. The results are discussed in the context of the meson-nucleon and hyperon-nucleon interactions. We conclude that the eta-proton interaction is significantly stronger than the eta'-proton interaction. Similarly, we found that the hyperon Lambda interacts with the nucleon considerably stronger than the hyperon Sigma, and that the interaction of K--proton is much stronger than this of the K+-proton.
Dynamics of the near threshold eta meson production in proton-proton interaction
R. Czyzykiewicz, P. MoSkal, HH. Adam, A. Budzanowski, E. Czerwinski, D. Gil, D. Grzonka, M. Hodana, M. Janusz, L. Jarczyk, B. Kamys, A. Khoukaz, K. Kilian, P. Klaja, B. Lorentz, W. Oelert, C. Piskor-Ignatowicz, J. Przerwa, B. Rejdych, J. Ritman, T. Sefzick, M. Siemaszko, M. Silarski, J. Smyrski, A. Taschner, K. Ulbrich, P. Winter, M. Wolke, P. Wustner, M. Zielinski, W. Zipper
abstract
We present the results of measurements of the analysing power for the pp -> pp eta reaction at the excess energies of Q = 10 and 36 MeV, and interpret these results within the framework of the meson exchange models. The determined values of the analysing power at both excess energies are consistent with zero implying that the eta meson is produced predominantly in s-wave.
Study of the He-3-eta system in d-p collisions
J. Smyrski, HH. Adam, A. Budzanowski, E. Czerwinski, R. Czyzykiewicz, D. Gil, D. Grzonka, M. Janusz, L. Jarczyk, B. Kamys, A. Khoukaz, P. Klaja, P. Moskal, W. Oelert, C. Piskor-Ignatowicz, J. Przerwa, J. Ritman, T. Rozek, T. Sefzick, A. Siemaszko, A. Taschner, P. Winter, M. Wolke, P. Wustner, W. Zipper
abstract
We have measured excitation functions for the dp -> He-3 X, (X = pi(0),eta) channels near the eta production threshold. The data were taken during a slow ramping of the COSY internal deuteron beam scattered on a proton target. The excitation function for the reaction dp -> He-3 pi(0) does not show any structure which could originate from the decay of He-3 - eta bound state. We measured also the threshold excitation curve for the dp -> He-3 X process, however, contrary to the SATURNE results, we observe no cusp near the eta threshold.
Measurement of the dp -> He-3 eta reaction near threshold
J. Smyrski, HH. Adam, A. Budzanowski, E. Czerwinski, R. Czyzykiewicz, D. Gil, D. Grzonka, M. Janusz, L. Jarczyk, B. Kamys, A. Khoukaz, P. Klaja, T. Mersmann, P. Moskal, W. Oelert, C. Piskor-Ignatowicz, J. Przerwa, B. Rejdych, J. Ritman, T. Rozek, T. Sefzick, M. Siemaszko, A. Taschner, P. Winter, M. Wolke, P. Wustner, W. Zipper
abstract
Total and differential cross sections for the dp -> He-3 eta reaction have been measured near threshold for He-3 center-of-mass momenta in the range from 17.1 MeV/c to 87.5 MeV/c. The data were taken during a slow ramping of the COSY internal deuteron beam scattered on a proton target detecting the He-3 ejectiles with the COSY-11 facility. The forward-backward asymmetries of the differential cross sections deviate clearly from zero for center-of-mass momenta above 50 MeV/c indicating the presence of higher partial waves in the final state. Below 50 MeV/c center-of-mass momenta a fit of the final state enhancement factor to the data of the total cross sections results in the He-3-eta scattering length of vertical bar a vertical bar = 4.3 +/- 0.5fm. (C) 2007 Elsevier B.V. All rights reserved.
Mechanism of near-threshold production of the eta meson
R. Czyzykiewicz, P. Moskal, HH. Adam, A. Budzanowski, E. Czerwinski, D. Gil, D. Grzonka, M. Hodana, M. Janusz, L. Jarczyk, B. Kamys, A. Khoukaz, K. Kilian, P. Klaja, B. Lorentz, W. Oelert, C. Piskor-Ignatowicz, J. Przerwa, B. Rejdych, J. Ritman, T. Sefzick, M. Siemaszko, J. Smyrski, A. Taschner, K. Ulbrich, P. Winter, M. Wolke, P. Wustner, W. Zipper
abstract
Measurements of the analyzing power for the pp -> pp eta reaction have been performed at excess energies of Q=10 and 36 MeV. The determined analyzing power is essentially consistent with zero, implying dominance of the s wave at both excess energies. The angular dependence of the analyzing power, combined with the isospin dependence of the total cross section for the eta meson production in nucleon-nucleon collisions, reveal that the excitation of the nucleon to the S-11(1535) resonance is predominantly due to the exchange of the pi meson between the colliding nucleons.
Eta and eta-prime mesons production at COSY-11
P. Moskal, H.-H. Adam, A. Budzanowski, E. Czerwinski, R. Czyzykiewicz, D. Gil, D. Grzonka, M. Janusz, L. Jarczyk, B. Kamys, A. Khoukaz, P. Klaja, J. Majewski, W. Oelert, C. Piskor-Ignatowicz, J. Przerwa, J. Ritman, B. Rejdych, T. Rozek, T. Sefzick, M. Siemaszko, J. Smyrski, A. Taeschner, P. Winter, M. Wolke, P. Wuestner, W. Zipper
abstract
The low emittance and small momentum spread of the proton and deuteron beams of the Cooler Synchrotron COSY combined with the high mass resolution of the COSY-11 detection system permit to study the creation of mesons in the nucleon-nucleon interaction down to the fraction of MeV with respect to the kinematical threshold. At such small excess energies, the ejectiles possess low relative momenta and are predominantly produced with the relative angular momentum equal to zero. Taking advantage of these conditions we have performed investigations aiming to determine the mechanism of the production of eta and eta' mesons in the collision of hadrons as well as the hadronic interaction of these mesons with nucleons and nuclei. In this proceedings we address the ongoing studies of the spin and isospin dependence for the production of the eta and eta' mesons in free and quasi-free nucleon-nucleon collisions. New results on the spin observables for the vec(p)p --> pp eta reaction, combined with the previously determined total cross section isospin dependence, reveal a statistically significant indication that the excitation of the nucleon to the S11(1535) resonance, the process which intermediates the production of the eta meson in the nucleon-nucleon interactions, is predominantly due to the exchange of the pi meson between the colliding nucleons.
General thoughts to the Kaon pair production in the threshold region
W. Oelert, H.-H. Adam, A. Budzanowski, E. Czerwinski, R. Czyzykiewicz, D. Gil, D. Grzonka, M. Janusz, L. Jarczyk, B. Kamys, A. Khoukaz, P. Klaja, P. Moskal, C. Piskor-Ignatowicz, J. Przerwa, T. Rozek, R. Santo, T. Sefzick, M. Siemaszko, J. Smyrski, A. Taschner, P. Winter, M. Wolke, P. Wustner, W. Zipper
abstract
Simple--minded thoughts about the cross sections for the reactions pp-->ppK+K- and pp-->ppK0K0 are presented, which certainly do not account for the complex coupled channel problem but rather provide some ideas into the mutual reaction dynamics.
Study of the production mechanism of the eta meson by means of analysing power measurements
R. Czyżykiewicz, P. Moskal, H.-H. Adam, A. Budzanowski, E. Czerwiński, D. Gil, D. Grzonka, M. Janusz, L. Jarczyk, B. Kamys, A. Khoukaz, P. Klaja, B. Lorentz, J. Majewski, W. Oelert, C. Piskor-Ignatowicz, J. Przerwa, J. Ritman, H. Rohdjess, T. Rozek, T. Sefzick, M. Siemaszko, J. Smyrski, A. Taeschner, K. Ulbrich, P. Winter, M. Wolke, P. Wuestner, W. Zipper
abstract
Information about the production mechanism of the eta meson in proton-proton collisions can be inferred by confronting the experimental studies on the analysing power for the p(pol)p --> pp eta reaction with the theoretical predictions of this observable. Results show that the predictions of pure pseudoscalar- or vector meson exchange model are insufficient to describe the analysing powers.
Near threshold eta meson production in dp collisions
C. Piskor-Ignatowicz, J. Smyrski, P. Moskal, H.-H. Adam, A. Budzanowski, E. Czerwiński, R. Czyżykiewicz, D. Gil, D. Grzonka, M. Janusz, L. Jarczyk, B. Kamys, A. Khoukaz, P. Klaja, J. Majewski, W. Oelert, J. Przerwa, J. Ritman, T. Rozek, T. Sefzick, M. Siemaszko, A. Taeschner, P. Winter, M. Wolke, P. Wuestner, W. Zipper
abstract
Preliminary results of recent measurements of the near threshold eta meson production in the dp-->dp eta reaction are presented. The experiment was performed at the COSY-Juelich accelerator with the use of the COSY-11 detection system. Data were taken for three values of deuteron beam momenta corresponding to excess energies of 3.2, 6.1 and 9.2 MeV. The energy dependence of the total cross section confirms a strong effect of the final state interaction.
General thoughts to the kaon pair production in the threshold region
W. Oelert, HH. Adam, A. Budzanowski, E. Czerwinski, R. Czyzykiewicz, D. Gil, D. Grzonka, M. Janusz, L. Jarczyk, B. Kamys, A. Khoukaz, P. Klaja, P. Moskal, C. Piskor-Ignatowicz, J. Przerwa, T. Rozek, R. Santo, T. Sefzick, M. Siemaszko, J. Smyrski, A. Taschner, P. Winter, M. Wolke, P. Wustner, W. Zipper
abstract
Simple-minded thoughts about the cross sections for the reactions pp -> ppK(+)K(-) and pp. ppK(0)K(0) are presented, which certainly do not account for the complex coupled channel problem but rather provide some ideas into the mutual reaction dynamics.
Study of the production mechanism of the eta meson by means of analysing power measurements
R. Czyzykiewicz, P. Moskal, HH. Adam, A. Budzanowski, E. Czerwinski, D. Gil, D. Grzonka, M. Janusz, L. Jarczyk, B. Kamys, A. Khoukaz, P. Klaja, B. Lorentz, J. Majewski, W. Oelert, C. Piskor-Ignatowicz, J. Przerwa, J. Ritman, H. Rohdjess, T. Rozek, T. Sefzick, M. Siemaszko, J. Smyrski, A. Taschner, K. Ulbrich, P. Winter, M. Wolke, P. Wustner, W. Zipper
abstract
Information about the production mechanism of the eta meson in proton-proton collisions can be inferred by confronting the experimental studies on the analysing power for the (p) over right arrowp -> pp eta reaction with the theoretical predictions of this observable. The determined analysing powers for Q=10 MeV and Q=36 MeV are consistent with zero. Results show that the predictions of pure pseudoscalar meson exchange model fairly describe the experimental data, while the predictions of pure vector meson exchange dominance model disagree with the data at the level of 4.3 sigma.
Near threshold eta meson production in dp collisions
C. Piskor-Ignatowicz, J. Smyrski, P. Moskal, HH. Adam, A. Budzanowski, E. Czerwinski, R. Czyzykiewicz, D. Gil, D. Grzonka, M. Janusz, L. Jarczyk, B. Kamys, A. Khoukaz, P. Klaja, J. Majewski, W. Oelert, J. Przerwa, J. Ritman, T. Rozek, T. Sefzick, M. Siemaszko, A. Taschner, P. Winter, M. Wolke, P. Wustner, W. Zipper
abstract
Preliminary results of recent measurements of the near threshold. meson production in the dp -> dp eta reaction are presented. The experiment was performed at the COSY-Juelich accelerator with the use of the COSY-11 detection system. Data were taken for three values of deuteron beam momenta corresponding to excess energies of 3.2, 6.1 and 9.2 MeV. The energy dependence of the total cross section con. rms a strong e. ect of the. nal state interaction.
Study of the low energy interaction of hadrons at COSY-11
P. Moskal, R. Czyżykiewicz, E. Czerwiński, D. Grzonka, A. Budzanowski, D. Gil, M. Janusz, L. Jarczyk, B. Kamys, A. Khoukaz, P. Klaja, W. Oelert, C. Piskor-Ignatowicz, J. Przerwa, B. Rejdych, J. Ritman, T. Sefzick, M. Siemaszko, M. Silarski, J. Smyrski, A. Täschner, M. Wolke, P. Wüstner, M. Zieliński, W. Zipper
abstract
We summarize the studies of the low energy hadronic interaction of the KK and pK system performed by the COSY-11 collaboration. We discuss also the question of the existence of the ??3He bound state in the context of the experiments conducted by means of the COSY-11 facility
Measurement of the dp -> He-3 eta reaction near threshold
J. Smyrski, H.-H. Adam, A. Budzanowski, E. Czerwiński, R. Czyżykiewicz, D. Gil, D. Grzonka, M. Janusz, L. Jarczyk, B. Kamys, A. Khoukaz, P. Klaja, T. Mersmann, P. Moskal, W. Oelert, C. Piskor-Ignatowicz, J. Przerwa, B. Rejdych, J. Ritman, T. Rozek, T. Sefzick, M. Siemaszko, A. Taeschner, P. Winter, M. Wolke, P. Wuestner, W. Zipper
abstract
Total and differential cross sections for the dp --> 3He eta reaction have been measured near threshold for 3He center-of-mass momenta in the range from 17.1 MeV/c to 87.5 MeV/c. The data were taken during a slow ramping of the COSY internal deuteron beam scattered on a proton target detecting the 3He ejectiles with the COSY-11 facility. The forward-backward asymmetries of the differential cross sections deviate clearly from zero for center-of-mass momenta above 50 MeV/c indicating the presence of higher partial waves in the final state. Below 50 MeV/c center-of-mass momenta a fit of the final state enhancement factor to the data of the total cross sections results in the 3He eta scattering length of a = |2.9 +/- 0.6| + i (3.2 +/- 0.4) fm.
Direct measurement of the total width of the eta prime meson
E. Czerwiński, P. Moskal, D. Grzonka, A. Budzanowski, R. Czyżykiewiczy, D. Gil, M. Janusz, L. Jarczyk, B. Kamys, A. Khoukaz, P. Klaja, W. Oelert, C. Piskor-Ignatowicz, J. Przerwa, B. Rejdych, J. Ritman, T. Sefzick, M. Siemaszko, M. Silarski, J. Smyrski, A. Täschner, M. Wolke, P. Wüstner, M. Zieliński, W. Zipper
abstract
Using stochastically cooled proton beam of the cooler synchrotron COSY and the COSY-11 apparatus we have measured the mass distribution of the eta prime meson producing it via the pp->ppeta' reaction. The preliminary analysis shows that the achieved experimental mass resolution amounts to about 0.3 MeV (FWHM). Such precision with about 2300 events gathered at five excess energies should permit for the extraction of the width of the eta' meson with an accuracy of about 10 keV. In this article we describe the method of the mea-surement and present preliminary results.
Study of the He-3 eta system in d p collisions
J. Smyrski, H.-H. Adam, A.Budzanowski, E. Czerwiński, R. Czyżykiewicz, D. Gil, D. Grzonka, M. Janusz, L. Jarczyk, B. Kamys, A. Khoukaz, P. Klaja, P. Moskal, W. Oelert, C. Piskor-Ignatowicz, J. Przerwa, J. Ritman, T. Rozek, T. Sefzick, M. Siemaszko, A. Taeschner, P. Winter, M. Wolke, P. Wuestner, W. Zipper
abstract
We have measured excitation functions for the d+p->3He+X, (X=pi0, eta) channels near the eta production threshold. The data were taken during a slow ramping of the COSY internal deuteron beam scattered on a proton target. The excitation function for the reaction d+p->3He+pi0 does not show any structure which could originate from the decay of 3He-eta bound state. We measured also the threshold excitation curve for the d+p->3He+X process, however, contrary to the SATURNE results, we observe no cusp near the eta threshold.
Mechanism of the close-to-threshold production of the eta meson
R. Czyzykiewicz, P. Moskal, H. -H. Adam, A. Budzanowski, E. Czerwinski, D. Gil, D. Grzonka, M. Hodana, M. Janusz, L. Jarczyk, B. Kamys, A. Khoukaz, K. Kilian, P. Klaja, B. Lorentz, W. Oelert, C. Piskor-Ignatowicz, J. Przerwa, B. Rejdych, J. Ritman, T. Sefzick, M. Siemaszko, J. Smyrski, A. Taeschner, K. Ulbrich, P. Winter, M. Wolke, P. Wuestner, W. Zipper
abstract
Measurements of the analysing power for the p(pol)p --> ppeta reaction have been performed in the close-to-threshold energy region at beam momenta of p_{beam}=2.010 and 2.085 GeV/c, corresponding to excess energies of Q=10 and 36 MeV, respectively. The determined analysing power is essentially consistent with zero implying that the eta meson is produced predominantly in the s-wave at both excess energies. The angular dependence of the analysing power, combined with the hitherto determined isospin dependence of the total cross section for the eta meson production in nucleon-nucleon collisions, reveal a statistically significant indication that the excitation of the nucleon to the S_{11}(1535) resonance, the process which intermediates the production of the eta meson, is predominantly due to the exchange of the pi meson between the colliding nucleons.
Experimental studies of the near threshold production of K+K- pairs at COSY-11
D. Gil, J. Smyrski
abstract
This paper sums up experimental studies of the near threshold production of K+K- pairs at COSY-11. The total cross section of the reaction pp -> ppK(+)K(-) has been measured at five excess energies below the phi production threshold with the magnetic spectrometer COSY-11. The new data show a significant enhancement of the total cross section compared to pure phase space expectations.
Study of the He-3-eta system in d-p collisions at COSY-11
J. Smyrski, HH. Adam, A. Budzanowski, E. Czerwinski, R. Czyzykiewicz, D. Gil, D. Grzonka, A. Heczko, M. Janusz, L. Jarczyk, B. Kamys, A. Khoukaz, K. Kilian, P. Klaja, J. Majewski, P. Moskal, W. Oelert, C. Piskor-Ignatowicz, J. Przerwa, J. Ritman, T. Rozek, R. Santo, T. Sefzick, M. Siemaszko, A. Taschner, P. Winter, M. Wolke, P. Wustner, Z. Zhang, W. Zipper
abstract
We present preliminary results from dp -> He-3 X, (X = pi(0),eta) measurements near the eta production threshold. The data were taken during a slow ramping of the COSY internal deuteron beam scattered on a proton target. The He-3 ejectiles were registered with the COSY-11 detection setup. The ongoing data analysis should deliver high precision data for the dp -> He-3 eta total and differential cross sections for the excess energies in the range from threshold up to 9 MeV. The preliminary excitation function for the reaction dp -> 3 He pi(0) does not show any structure which Could originate from the decay of He-3 - eta bound state. We present also a threshold excitation curve for the dp - He-3 X channel. Contrary to corresponding results from SATURNE we see no cusp in the vicinity of the eta threshold.
The analyzing power for the (p)over-right-arrowp -> pp eta reaction at Q=10 MeV
R. Czyzykiewicz, P. Moskal, HH. Adam, A. Budzanowski, E. Czerwinski, D. Gil, D. Grzonka, M. Janusz, L. Jarczyk, B. Kamys, A. Khoukaz, K. Kilian, P. Klaja, B. Lorentz, J. Majewski, W. Oelert, C. Piskor-Ignatowicz, J. Przerwa, J. Ritman, H. Rohdjess, T. Rozek, R. Santo, T. Sefzick, M. Siemaszko, J. Smyrski, A. Taschner, K. Ulbrich, P. Winter, M. Wolke, P. Wustner, Z. Zhang, W. Zipper
abstract
The analyzing power A(y) for the (p) over right arrowp -> pp eta reaction has been determined at the beam momentum p(beam) = 2010 MeV/c, corresponding to the excess energy Q = 10 MeV. In the paper the method of the data analysis is briefly presented.
The Analysing power for the polarized-p p ---> p p eta reaction at Q=10MeV
R. Czyzykiewicz, P. Moskal, H.-H. Adam, A. Budzanowski, E. Czerwinski, D. Gil, D. Grzonka, M. Janusz, L. Jarczyk, B. Kamys, A. Khoukaz, K. Kilian, P. Klaja, B. Lorentz, J. Majewski, W. Oelert, C. Piskor-Ignatowicz, J. Przerwa, J. Ritman, H. Rohdjess, T. Rozek, R. Santo, T. Sefzick, M. Siemaszko, J. Smyrski, A. Taeschner, K. Ulbrich, P. Winter, M. Wolke, P. Wuestner, Z. Zhang, W. Zipper
abstract
The analyzing power A_y for the p(pol)p --> pp eta reaction has been determined at the beam momentum p_{beam}=2010 MeV/c, corresponding to the excess energy Q=10 MeV. In the paper the method of the data analysis is briefly presented.
Study of the He-3 - eta system in d-p collisions at COSY-11
J. Smyrski, H.-H. Adam, A. Budzanowski, E. Czerwinski, R. Czyzykiewicz, D. Gil, D. Grzonka, A. Heczko, M. Janusz, L. Jarczyk, B. Kamys, A. Khoukaz, K. Kilian, P. Klaja, J. Majewski, P. Moskal, W. Oelert, C. Piskor-Ignatowicz, J. Przerwa, J. Ritman, T. Rozek, R. Santo, T. Sefzick, M. Siemaszko, A. Taeschner, P. Winter, M. Wolke, P. Wuestner, Z. Zhang, W. Zipper
abstract
We present preliminary results from dp --> 3He X (X=pi0,eta) measurements near the eta production threshold. The data were taken during a slow ramping of the COSY internal deuteron beam scattered on a proton target. The 3He ejectiles were registered with the COSY-11 detection setup. The ongoing data analysis should deliver high precision data for the dp --> 3He eta total and differential cross sections for the excess energies in the range from threshold up to 9 MeV. The preliminary excitation function for the reaction dp --> 3He pi0 does not show any structure which could originate from the decay of 3He-eta bound state. We present also a threshold excitation curve for the dp --> 3He X channel. Contrary to corresponding results from SATURNE we see no cusp in the vicinity of the eta threshold.
Correlation femtoscopy for studying eta meson production mechanism
P. Klaja, P. Moskal, H.-H. Adam, A. Budzanowski, E. Czerwinski, R. Czyzykiewicz, D. Gil, D. Grzonka, M. Janusz, L. Jarczyk, B. Kamys, A. Khoukaz, K. Kilian, J. Majewski, W. Migdal, W. Oelert, C. Piskor-Ignatowicz, J. Przerwa, J. Ritman, T. Rozek, R. Santo, T. Sefzick, M. Siemaszko, J. Smyrski, A. Taeschner, P. Winter, M. Wolke, P. Wuestner, Z. Zhang, W. Zipper
abstract
The high statistics data from the pp -> ppeta reaction measurement, delivered by the COSY-11 collaboration, are now being evaluated using the correlation femtoscopy technique. This method is based on the relative momentum correlations of two emitted protons and may permit determination of the size of the reaction volume. For the very first time, we apply an intensity interferometry technique to study the mechanism of the meson production via the nucleon-nucleon interaction close to the kinematical threshold. We invented a method to determine correlation function for the ppeta system free from the physical multi-pion production background. We show the comparison of experimental results with theoretical predictions and appraise the accuracy achieved for the determination of the size of the emission source.
Spin observables in hyperon production
M. Maggiora, F. Balestra, Y. Bedfer, R. Bertini, LC. Bland, F. Brochard, MP. Bussa, V. Chalyshev, S. Choi, M. Debrowski, M. Dzemidzic, JC. Faivre, IV. Falomkin, L. Fava, L. Ferrero, J. Foryciarz, V. Frolov, I. Frohlich, R. Garfagnini, D. Gill, A. Grasso, S. Heinz, VV. Ivanov, WW. Jacobs, W. Kuhn, A. Maggiora, A. Manara, D. Panzieri, HW. Pfaff, G. Piragino, GB. Pontecorvo, A. Popov, J. Ritman, P. Salabura, F. Tosello, SE. Vigdor, G. Zosi
abstract
The first exclusive measurements of the spin transfer parameter D-NN in the reaction (p) over right arrow p --> pK(+)<(Lambda)over right arrow> has been performed at Saturne with the polarized beam and with the DISTO spectrometer. The results suggest an OBE mechanism dominated by kaon exchange.
Meson and hyperon production results from the DISTO spectrometer at SATURNE
P. Salabura, F. Balestra, Y. Bedfer, R. Bertini, LC. Bland, F. Brochard, MP. Bussa, V. Chalyshev, S. Choi, M. Dzemidzic, JC. Faivre, IV. Falomkin, L. Fava, L. Ferrero, J. Foryciarz, V. Frolov, I. Frohlich, R. Garfagnini, D. Gill, A. Grasso, S. Heinz, VV. Ivanov, WW. Jacobs, W. Kuhn, A. Maggiora, M. Maggiora, A. Manara, D. Panzieri, HW. Pfaff, G. Piragino, GB. Pontecorvo, A. Popov, J. Ritmann, F. Tosello, SE. Vigdor, G. Zosi
abstract
The production of eta, eta', omega, phi, mesons, as well as Lambda and Sigma hyperons has been measured in proton-proton reactions with an incident beam momentum of 3.67 GeV/c with DISTO spectrometer at SATURNE. The first observation of the phi meson near the production threshold and the phi/omega cross sections ratio has been compared to predictions based on the OZI rule and on one-boson-exchange models. Measured inclusive cross section for K- mesons production is about a factor of 20 lower than for inlcusive K+ production at the same CM energy above threshold. This fact is in strong contrast to cross sections observed in sub-threshold heavy ion collisions. The production of eta and eta' masons has also been measured, in an effort to gain information on the eta'-nucleon coupling. The normal spin transfer coefficient (D-N N) has been determined for exclusive hyperon production with a polarized beam. A large negative coefficient has been observed, which is qualitatively consistent with expectations for a mechanism dominated by kaon-exchange and rescattering.
K- meson production in the proton-proton reaction at 3.67 GeV/c
F. Balestra, Y. Bedfer, R. Bertini, LC. Bland, A. Brenschede, F. Brochard, MP. Bussa, V. Tchalyshev, SH. Choi, M. Debowski, M. Dzemidzic, JC. Faivre, IV. Falomkin, L. Fava, L. Ferrero, J. Foryciarz, I. Frohlich, V. Frolov, R. Garfagnini, D. Gill, A. Grasso, E. Grosse, S. Heinz, VV. Ivanov, WW. Jacobs, W. Kuhn, A. Maggiora, M. Maggiora, A. Manara, D. Panzieri, HW. Pfaff, G. Piragino, GB. Pontecorvo, A. Popov, J. Ritman, P. Salabura, F. Tosello, SE. Vigdor, G. Zosi
abstract
The total cross section of the reaction pp --> ppK(+)K(-) has been determined for proton-proton reactions with p(beam) = 3.67 GeV/c. This represents the first cross section measurement of the pp --> ppK(-)K(+) channel near threshold, and is equivalent to the inclusive pp --> ppK(-)X cross section at this beam momentum. The cross section determined at this beam momentum is about a factor 20 lower than that for inclusive pp --> ppK(+)X meson production at the same CM energy above the corresponding threshold. This large difference in the K+ and K- meson inclusive production cross sections in proton-proton reactions is in strong contrast to cross sections measured in sub-threshold heavy ion collisions, which are similar in magnitude at the same energy per nucleon below the respective thresholds. (C) 1999 Published by Elsevier Science B.V. All rights reserved.
Spin transfer in exclusive Lambda production from (p)over-right-arrowp collisions at 3.67 GeV/c
F. Balestra, Y. Bedfer, R. Bertini, LC. Bland, A. Brenschede, F. Brochard, MP. Bussa, V. Chalyshev, S. Choi, M. Debowski, M. Dzemidzic, JC. Faivre, IV. Falomkin, L. Fava, L. Ferrero, J. Foryciarz, V. Frolov, R. Garfagnini, D. Gill, A. Grasso, S. Heinz, VV. Ivanov, WW. Jacobs, W. Kuhn, A. Maggiora, M. Maggiora, A. Manara, D. Panzieri, HW. Pfaff, G. Piragino, GB. Pontecorvo, A. Popov, J. Ritman, P. Salabura, F. Tosello, SE. Vigdor, G. Zosi
abstract
We report the first polarization transfer measurements for exclusive hyperon production reactions. The normal spin transfer coefficient D-NN for (p) over right arrow p --> pK(+)<(Lambda)over right arrow> is large and negative for forward Lambda production at a beam momentum of 3.67 GeV/c, a result qualitatively consistent with expectations for a mechanism dominated by kaon exchange and rescattering. The sign of D-NN is opposite to that observed in the fragmentation regime for inclusive Lambda production at much higher energies.
DISTO: a large acceptance multiparticle spectrometer for 1-3 GeV proton beams
F. Balestra, Y. Bedfer, R. Bertini, LC. Bland, A. Brenschede, F. Brochard, MP. Bussa, V. Chalyshev, S. Choi, M. Debowski, M. Dzemidzic, JC. Faivre, IV. Falomkin, L. Fava, L. Ferrero, J. Foryciarz, V. Frolov, R. Garfagnini, D. Gill, A. Grasso, E. Grosse, S. Heinz, WW. Jacobs, W. Kuhn, A. Maggiora, M. Maggiora, A. Manara, D. Panzieri, HW. Pfaff, G. Piragino, GB. Pontecorvo, A. Popov, J. Ritman, P. Salabura, P. Senger, J. Stroth, F. Tosello, SE. Vigdor, B. Zalikhanov, G. Zosi
abstract
A magnetic spectrometer system has been constructed for the study of reactions with multiple charged particles in the final state, induced by polarized proton beams of few GeV energy. The system is based on a large-gap dipole magnet, with a liquid hydrogen target nd scintillating fiber tracking detectors embedded inside the magnet. Multiwire proportional chambers, plastic scintillator hodoscopes, and threshold Cherenkov detectors placed outside the magnet provide additional tracking,triggering and particle identification capabilities. The system has been applied to study exclusive hyperon as well as pseudoscalar and vector meson production reactions at bombarding energies below 3 GeV. Additionally, it has been used to monitor the proton beam polarization at Laboratoire National Saturne. The components and performance of the system are reported. (C) 1999 Elsevier Science B.V. All rights reserved.
Production of phi and omega mesons in near-threshold pp reactions
F. Balestra, Y. Bedfer, R. Bertini, LC. Bland, A. Brenschede, F. Brochard, MP. Bussa, V. Chalyshev, SH. Choi, M. Debowski, M. Dzemidzic, IV. Falomkin, JC. Faivre, L. Fava, L. Ferrero, J. Foryciarz, V. Frolov, R. Garfagnini, D. Gill, A. Grasso, E. Grosse, S. Heinz, VV. Ivanov, WW. Jacobs, W. Kuhn, A. Maggiora, M. Maggiora, A. Manara, D. Panzieri, HW. Pfaff, G. Piragino, GB. Pontecorvo, A. Popov, J. Ritman, P. Salabura, P. Senger, J. Stroth, F. Tosello, SE. Vigdor, G. Zosi
abstract
The ratio of the exclusive production cross sections for phi and omega mesons has been measured in pp reactions at T-beam = 2.85 GeV. The observed phi/omega ratio is (3.7 +/- 0.7(-0.9)(+1.2)) X 10(-3). After phase space corrections, this ratio is about a factor of 10 enhanced relative to naive predictions based upon the Okubo-Zweig-Iizuka rule, in comparison to an enhancement by a factor of similar to 3 previously observed at higher energies. The modest increase of this enhancement near the production threshold is compared to the much larger increase of the phi/omega ratio observed in specific channels of <(p)over bar p> annihilation experiments. [S0031-9007(98)07664-9].
The DISTO first level trigger at SATURNE
F. Balestra, Y. Bedfer, R. Bertini, LC. Bland, A. Brenschede, F. Brochard, MP. Bussa, S. Choi, M. Debowski, M. Dzemidzic, JC. Faivre, L. Fava, L. Ferrero, J. Foryciarz, V. Frolov, R. Garfagnini, D. Gill, A. Grasso, S. Heinz, WW. Jacobs, W. Kuhn, A. Maggiora, M. Maggiora, A. Manara, D. Panzieri, H. Pfaff, GB. Pontecorvo, A. Popov, J. Ritman, P. Salabura, J. Stroth, V. Tchalyshev, F. Tosello, SE. Vigdor, G. Zosi
abstract
The DISTO collaboration has built a large-acceptance magnetic spectrometer designed to provide broad kinematic coverage of multi-particle final states produced in pi, scattering. The spectrometer has been installed in the polarized proton beam of the Saturne accelerator in Saclay to study polarization observables in the (p) over right arrow p --> pK(+)(Y) over right arrow (Y = Lambda, Sigma(0) or Y*) reaction and vector meson production (phi,omega and rho) in pp collisions. The common signature of such events is the multiplicity of four charged particles in the final state. A flexible Ist level trigger which uses topological information from fast detectors (scintillating fibers and hodoscope) has been built. It is completely software programmable through a menu-driven user interface and allows switching between production and monitor triggers on successive beam spills.
The DISTO data acquisition system at SATURNE
F. Balestra, Y. Bedfer, R. Bertini, LC. Bland, A. Brenschede, F. Brochard, MP. Bussa, S. Choi, M. Debowski, M. Dzemidzic, IV. Falomkin, JC. Faivre, L. Fava, L. Ferrero, J. Foryciarz, V. Frolov, R. Garfagnini, D. Gill, A. Grasso, E. Grosse, WW. Jacobs, W. Kuhn, A. Maggiora, M. Maggiora, A. Manara, D. Panzieri, H. Pfaff, G. Piragino, GB. Pontecorvo, A. Popov, J. Ritman, P. Salabura, V. Tchalyshev, F. Tosello, SE. Vigdor, G. Zosi
abstract
The DISTO collaboration has built a large-acceptance magnetic spectrometer designed to provide broad kinematic coverage of multiparticle final states produced in py, scattering. The spectrometer has been installed in the polarized proton beam of the Saturne accelerator in Saclay to study polarization observables in the (p) over right arrow p --> pK(+)(Y) over right arrow (Y = Lambda, Sigma(0) or Y*) reaction and vector meson production (phi,omega and rho) in pp collisions. The data acquisition system is based on a VME 68030 CPU running the OS/9 operating system, housed in a single VME crate together with the CAMAC interface, the triple port ECL memories, and four RISC R3000 CPU. The digitization of signals from the detectors is made by PCOS III and FERA front-end electronics. Data of several events belonging to a single Saturne extraction are stored in VME triple-port ECL memories using a hardwired fast sequencer. The buffer, optionally filtered by the RISC R3000 CPU, is recorded on a DLT cassette by DAQ CPU using the on-board SCSI interface during the acceleration cycle. Two UNIX workstations are connected to the VME CPUs through a fast parallel bus and the Local Area Network. They analyze a subset of events for on-line monitoring. The data acquisition system is able to read and record 3500 ev/burst in the present configuration with a dead time of 15%.
