Journal Article

PreJuSER-43632

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Experimental study of pp eta dynamics in the pp -> pp eta reaction

Moskal, P.FZJ* ; Adam, H.-H.FZJ* ; Budzanowski, A. ; Czyzykiewicz, R.FZJ* ; Grzonka, D.FZJ* ; Janusz, M. ; Jarczyk, L. ; Kamys, B. ; Khoukaz, A.FZJ* ; Kilian, K.FZJ* ; Klaja, P. ; Kowina, P.FZJ* ; Oelert, W.FZJ* ; Piskor-Ignatowicz, C. ; Przerwa, J. ; Rozek, T.FZJ* ; Santo, R. ; Sefzick, T.FZJ* ; Siemaszko, M. ; Smyrski, J.FZJ* ; Strzalkowski, A.FZJ* ; Täschner, A.FZJ* ; Winter, P.FZJ* ; Wolke, M.FZJ* ; Wüstner, P.FZJ* ; Zipper, W.

2004
Inst. Woodbury, NY

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Please use a persistent id in citations: http://hdl.handle.net/2128/1656  doi:10.1103/PhysRevC.69.025203

Abstract: A high statistics measurement of the pp-->ppeta reaction at an excess energy of Q=15.5 MeV has been performed at the internal beam facility COSY-11. The stochastically cooled proton beam and the used detection system allowed to determine the momenta of the outgoing protons with a precision of 4 MeV/c (sigma) in the center-of-mass frame. The determination of the four-momentum vectors of both outgoing protons allowed to derive the complete kinematical information of the etapp system. An unexpectedly large enhancement of the occupation density in the kinematical regions of low proton-eta relative momenta is observed. A description taking the proton-proton and the eta-proton interaction into account and assuming an on-shell incoherent pair-wise interaction among the produced particles fails to explain this strong effect. Its understanding will require a rigorous three-body approach to the ppeta system and the precise determination of contributions from higher partial waves. We also present an invariant mass spectrum of the proton-proton system determined at Q=4.5 MeV. Interestingly, the enhancement at large relative momenta between protons is visible also at such a small excess energy. In contrast to all other determined angular distributions, the orientation of the emission plane with respect to the beam direction is extracted to be anisotropic.

Keyword(s): p p: inelastic scattering ; eta: hadroproduction ; channel cross section: momentum transfer ; Dalitz plot ; three-body problem ; p: momentum spectrum ; partial wave analysis ; mass spectrum: (2p) ; angular distribution ; mass spectrum: missing-mass ; experimental results ; Juelich COSY PS ; bibliography ; p p --> 2p eta ; 2.027 GeV/c

Note: Record converted from VDB: 12.11.2012; Dedicated to Adam Strzalkowski on the occasion of his 80th birthday; 18 pages, 27 figures, submitted to Phys. Rev. C Journal-ref: Phys. Rev. C 69 (2004) 025203

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Contributing Institute(s):

1. Institut 1 (Experimentelle Kernphysik I) (IKP-E-I)

Research Program(s):

1. Physik der Hadronen (M01)

Appears in the scientific report 2004
Notes: This version is available at the following Publisher URL: http://prc.aps.org

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