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.Comment: Presented at 10th International Workshop on Meson Production,
  Properties and Interaction (MESON 2008), Cracow, Poland, 6 - 10 June 200

A. BUDZANOWSKI

A. KHOUKAZ

A. TÄSCHNER

B. KAMYS

B. REJDYCH

Bass S. D.

C. PISKOR-IGNATOWICZ

D. GIL

D. GRZONKA

E. CZERWIŃSKI

J. PRZERWA

J. RITMAN

J. SMYRSKI

J. ZDEBIK

L. JARCZYK

M. J. ZIELIŃSKI

M. SIEMASZKO

M. SILARSKI

M. WOLKE

P. KLAJA

P. MOSKAL

P. WÜSTNER

R. CZYŻYKIEWICZ

T. JOHANSSON

T. SEFZICK

W. KRZEMIEŃ

W. OELERT

W. ZIPPER

International Journal of Modern Physics A

English

arXiv

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

Przerwa, J.

Moskal, P.

Budzanowski, A.

et, al

Juelich Shared Electronic Resources

arXiv:0810.1406v2  [nucl-ex]  15 Oct 2008June 22, 2013 4:22 WSPC/INSTRUCTION FILE przerwa˙meson08International Journal of Modern Physics Ac© World Scientific Publishing CompanyISOSPIN DEPENDENCE OF THE η′ MESON PRODUCTION INNUCLEON-NUCLEON COLLISIONSJ. Przerwa⋆,∗, P. Moskal⋆,$, A. Budzanowski#, E. Czerwin´ski⋆,$, R. Czyz˙ykiewicz⋆, 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$,M. Siemaszko&, M. Silarski⋆, J. Smyrski⋆, A. Ta¨schner%, M. Wolke$, P. Wu¨stner$, J. Zdebik⋆,M. J. Zielin´ski⋆, W. Zipper&⋆Institute of Physics, Jagellonian University, Cracow, Poland$IKP and ZEL, Forschungszentrum Ju¨lich,Ju¨lich, Germany#Institute of Nuclear Physics, Cracow, Poland@Department of Physics and Astronomy, Uppsala University, Sweden%IKP, Westfa¨lische Wilhelms-Universita¨t, Mu¨nster, Germany&Institute of Physics, University of Silesia, Katowice, PolandA comparison of the close–to–threshold total cross section for the η′ production inpp → ppη′ and pn → pnη′ reactions constitutes a tool to investigate the η′ me-son structure and the reaction mechanism in the channels of isospin I = 0 and I = 1 andmay provide insight into the flavour-singlet (perhaps also into gluonium) content of theη′ meson.In this contribution we present preliminary results of measurement of the quasi-free pro-duction of the η′ meson in the proton-neutron collisions conducted using the COSY-11facility.Keywords: near threshold meson production; quasi-free reaction1. IntroductionIn the framework of the quark model the η′ meson is predominantly a flavour-singlet combination of quark-antiquark pairs, and it is expected to mix with purelygluonic states. Therefore, additionally to the production mechanisms associatedwith meson exchange1,2 it is also possible that η′ meson is produced from excitedglue in the interaction region of the colliding nucleons, which couple to the η′ mesondirectly via its gluonic component or through its SU(3)-flavour-singlet admixture3.As suggested in reference4, the η′ meson production via the colour-singlet objectdoes not depend on the total isospin of the colliding nucleons and should lead tothe same amplitudes of the production for the pn→ pnη′ and pp→ ppη′ reactions.In case of the η meson, the ratio of the total cross sections for the reactions pn→ pnηand pp→ ppη was determined to be Rη ≈ 6.55, and Rη ≈ 3 at threshold6, whatsuggest the dominance of isovector meson exchange in the η production in nucleon-∗E-mail address: j.przerwa@fz-juelich.de1June 22, 2013 4:22 WSPC/INSTRUCTION FILE przerwa˙meson082 J. Przerwa et al. – COSY–11 Collaborationnucleon collisions. Since the quark structure of η and η′ mesons is similar, in case ofthe dominant isovector meson exchange – by the analogy to the η meson production– we can expect that the ratio Rη′ should be large. If however η′ meson is producedvia its flavour-blind gluonium component from the colour-singlet glue excited inthe interaction region the ratio should approach unity after corrections for theinitial and final state interactions. The close–to–threshold excitation function forthe pp→ ppη′ reaction has already been established7 and the determination of thetotal cross section for the η′ meson production in the proton-neutron interactionconstitutes the aim of the work reported in this contribution.2. ExperimentIn August 2004 using the COSY–11 facility8 we have conducted a measurement ofthe η′ meson production in the proton-neutron collision. The experiment has beenrealized using a proton beam of the cooler synchrotron COSY 9 and a cluster jetdeuteron target 10. Proton and neutron outgoing from the pn→ pnη reaction havebeen registered by means of the COSY-11 facility. For the data analysis the pro-ton from the deuteron is considered as a spectator which does not interact with thebombarding proton, but escapes untouched and hits the detector carrying the Fermimomentum possessed exactly at the time of the reaction. The experiment is basedon the registration of all outgoing nucleons from the pd→ psppnX reaction6. Fastprotons are measured in two drift chambers and scintillator detectors 8, neutronsare registered in the neutral particle detector 11, and slow spectator protons mov-ing upwords to the beam are measured by the dedicated silicon-pad detector 12.Fig. 1(left) shows energy losses in the 1st layer of the spectator detector versus 2ndlayer. Slow spectator protons are stopped in the first or second layer of the detectorwhereas fast particles cross both detection layers. Having the deposited energy andthe emission angle we calculate the kinetic energy of the spectator proton and itsmomentum. Fig. 1(right) shows momentum distribution of protons considered as aspectator as determined at COSY-11 with a deuteron target and a proton beam withmomentum of 3.35 GeV/c (points) compared with simulations taking into accounta Fermi motion of nucleons inside the deuteron (solid line).Application of the missing mass technique allows to identify events with thecreation of the meson under investigation. The total energy available for the quasi-free proton-neutron reaction can be calculated for each event from the vector of themomenta of the spectator and beam protons. The absolute momentum of neutronsis determined from the time-of-flight between the target and the neutron detector.Fig.2(left) presents the time-of-flight distribution – for neutral particles – measuredbetween the target and the neutral particle detector. A clear signal originating fromthe gamma rays is seen over a broad enhancement from neutrons. This histogramshows that discrimination between signals originating from neutrons and gammaquanta can be done by a cut on the time of flight. From the Monte Carlo simulationsof the pn → pnη′ reaction the largest expected momentum value of the neutron isJune 22, 2013 4:22 WSPC/INSTRUCTION FILE przerwa˙meson08J. Przerwa et al. – COSY–11 Collaboration 3eqaul to 1.4 GeV/c which corresponds to the time–of-flight value of 28.5 ns as itis indicated by an arrow in Fig. 2(left). Neutrons having time–of–flight below thisvalue originate from pn → pn pions reactions and are not taken for the furtheranalysis.0123456789100 1 2 3 4 5 6 7 8 9 10energy loss in 2nd layer [MeV]energy loss in 1st layer [MeV]0100020003000400050000 0.02 0.04 0.06 0.08 0.1 0.12 0.14PF [GeV / c ]Fig. 1. Left: Energy losses in the first layer versus the second layer as measured at COSY–11with a deuteron target and a proton beam with momentum of 3.35 GeV/c. Right: Momentumdistribution of the proton spectator as reconstructed in the experiment (points) in comparisonwith simulation taking into account Fermi momentum distribution of nucleons inside the deuteron(solid histogram).020040060080010001200x 10 210 20 30 40 50 60time of flight [ ns ]counts11010 210 30 10 20 30 40 50 60Q [ MeV ]σ [ nb ]PRELIMINARYFig. 2. Left: Time–of–flight distribution between the target and the neutron detector as obtainedafter the time walk correction under condition that in coincidence with neutral particle also twocharged particles were identified. Right: Total cross sections for the pp → ppη′ reaction as afunction of the excess energy (open symbols). Upper limit for the total cross section for thepn→ pnη′ reaction as a function of the excess energy (closed symbols).Due to the smaller efficiency and lower resolution for the registration of theJune 22, 2013 4:22 WSPC/INSTRUCTION FILE przerwa˙meson084 J. Przerwa et al. – COSY–11 Collaborationquasi-free pn → pn meson reaction in comparison to the measurements of theproton-proton reactions, the elaboration of the data encounters problems of lowstatistics. Therefore, the excess energy range for Q ≥ 0 has been divided only intofour intervals of 8 MeV width. For each interval we have calculated the missing mass.Next, from events with negative Q value the corresponding background missingmass spectrum was constructed, shifted to the kinematical limit and normalizedto the experimental distribution at the very low mass values where no events fromthe η′ are expected. Detailed description of the method used for the backgroundsubtraction can be found in the dedicated article13. After subtracting missing massdistributions for the negative values of Q from spectra for Q values larger than 0 –due to the very high signal–to-background ratio – at the present stage of the dataanalysis, the signal from the η′ meson was found to be statistically insignificant.Nevertheless, having the luminosity – established from the number of the quasi-free proton-proton elastic scattering events 14 – and the detection efficiency of theCOSY-11 system we have estimated the upper limit of the total cross section forthe quasi-free pn→ pnη′ reaction. The prelimnary result is shown in Fig. 2(right).3. AcknowledgmentsWe acknowledge the support by the European Community under the FP6 pro-gramme (Hadron Physics, RII3-CT-2004-506078), by the Polish Ministry of Scienceand Higher Education under grants No. 3240/H03/2006/31, 1202/DFG/2007/03,0082/B/H03/2008/34, and by the German Research Foundation (DFG).References1. K. Nakayama et al., Phys. Rev. C 61, 024001 (2000).2. L. P. Kaptari, B. Ka¨mpfer, e-Print: arXiv:0804.2019.3. S. D. Bass, Phys. Scripta T 99, 96 (2002).4. S. D. Bass, Phys. Lett. B 463, 286 (1999).5. H. Calen et al., Phys. Rev. C 58, 2667 (1998).6. P. Moskal et al., e-Print: arXiv:0807.0722 (2008).7. P. Moskal et al., Phys. Lett. B 474, 416 (2000);A. Khoukaz et al., Eur. Phys. J. A 20, 345 (2004);F. Balestra et al., Phys. Lett. B 491, 29 (2000);P. Moskal et al., Phys. Rev. Lett. 80, 3202 (1998).8. S. Brauksiepe et al., Nucl. Instr. & Meth. A 376, 397 (1996);P. Klaja et al., AIP Conf. Proc. 796, 160 (2005);J. Smyrski et al., Nucl. Instr. & Meth. A 541, 574 (2005).9. D. Prasuhn et al., Nucl. Instr. & Meth. A 441, 167 (2000).10. H. Dombrowski et al., Nucl. Instr. & Meth. A 386, 228 (1997).11. J. Przerwa et al., Int. J. of Mod. Phys. A 20, 625 (2005).12. R. Bilger et al., Nucl. Instr. & Meth. A 457, 64 (2001).13. P. Moskal et al., J. Phys. G 32, 629 (2006).14. P. Moskal, R. Czyz˙ykiewicz, AIP Conf. Proc. 950, 118 (2007).

ISOSPIN DEPENDENCE OF THE eta ' MESON PRODUCTION IN NUCLEON-NUCLEON COLLISIONS

Crossref

ISOSPIN DEPENDENCE OF THE η' MESON PRODUCTION IN NUCLEON-NUCLEON COLLISIONS

A comparison of the close-to-threshold total cross section for the eta' production in pp -&gt; pp eta' and pn -&gt; 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.</p

Czerwinski, E.

Czyzykiewicz, R.

Gil, D.

Grzonka, D.

Jarczyk, L.

Johansson, Tord,

Kamys, B.

Khoukaz, A.

Klaja, P.

Krzemien, W.

Oelert, W.

Piskor-Ignatowicz, C.

Ritman, J.

Rejdych, B.

Sefzick, T.

Siemaszko, M.

Silarski, M.

Smyrski, J.

Taschner, A.

Wolke, M.

Wustner, P.

Zdebik, J.

Zielinski, M. J.

Zipper, W.

Swepub

Przerwa, Joanna

Moskal, Paweł

Czerwiński, Eryk

Czyżykiewicz, Rafał

Gil, Damian

Jarczyk, Lucjan

Johansson, T.

Kamys, Bogusław

Klaja, Paweł

Krzemień, Wojciech

Piskor-Ignatowicz, Cezary

Rejdych-Iwanek, Barbara

Silarski, Michał

Smyrski, Jerzy

Täschner, A.

Wüstner, P.

Zdebik, Jarosław

Zieliński, Marcin

Jagiellonian Univeristy Repository

Isospin dependence of the ${\eta }'$ meson production in nucleon-nucleon collisions

http://juser.fz-juelich.de/record/8502/files/0810.1406v2.pdf