ENTRY O0785 20120520 O048O078500000001 SUBENT O0785001 20120520 O048O078500100001 BIB 11 68 O078500100002 TITLE Measurement of the ETA production in proton-proton O078500100003 collisions with the COSY time-of-flight spectrometer O078500100004 AUTHOR (M.Abdel-Bary, S.Abdel-Samad, R.Bilger, O078500100005 K.-Th.Brinkmann, H.Clement, S.Dshemuchadse, O078500100006 E.Dorochkevitch, H.Dutz, W.Eyrich, A.Erhardt, D.Filges,O078500100007 A.Filippi, H.Freiesleben, M.Fritsch, R.Geyer, O078500100008 A.Gillitzer, D.Hesselbarth, B.Jakob, L.Karsch, O078500100009 K.Kilian, H.Koch, J.Kress, E.Kuhlmann, S.Marcello, O078500100010 S.Marwinski, S.Mauro, W.Meyer, P.Michel, K.Moeller, O078500100011 H.P.Morsch, L.Naumann, N.Paul, M.Richter, E.Roderburg, O078500100012 M.Rogge, A.Schamlott, M.Schmitz, P.Schoenmeier, O078500100013 M.Schulte-Wissermann, W.Schroeder,T.Sefzick,F.Stinzing,O078500100014 G.Y.Sun, G.J.Wagner, M.Wagner, A.Wilms,P.Wintz,S.Wirth,O078500100015 P.Zupranski,The COSY-TOF Collaboration) O078500100016 INSTITUTE (2GERBOC) Institut fuer Experimentalphysik O078500100017 (2GERBON) Physikalisches Institut O078500100018 (2GERDRE) Institut fuer Kern- und Teilchenphysik O078500100019 (2GERUEN) Physikalisches Institut O078500100020 (2GERJUL) Institut fuer Kernphysik O078500100021 (2GERZFK) Institut fuer Kern- und Hadronenphysik O078500100022 (2ITYTUR) INFN Torino O078500100023 (2GERTUE) Physikalisches Institut O078500100024 (3POLIPJ) Andrzej Soltan Institute for Nuclear Studies O078500100025 REFERENCE (J,EPJ/A,16,127,2003) O078500100026 FACILITY (SYNCH,2GERJUL) Julich Cooler Synchrotron COSY with theO078500100027 time-of-flight spectrometer. O078500100028 SAMPLE A 4 mm thick liquid hydrogen target enclosed with O078500100029 plastic foils of only 0.9 micrometers thickness. O078500100030 DETECTOR (SCIN) The start and stop counters have azimuthal O078500100031 symmetry with holes for the beam such that only O078500100032 reaction particles hit the counters. Three O078500100033 scintillators with holes of 8 mm, 5 mm and 2 mm O078500100034 diameter placed 1 m, 0.5 m and 10 cm in front of the O078500100035 target are used to veto the beam halo. The incident O078500100036 beam and the whole detection system are enclosed in O078500100037 vacuum in order to minimize multiple scattering and O078500100038 secondary reactions. O078500100039 A 0.5 mm thick scintillator counter is used as start O078500100040 counter. It has an inner hole of 3 mm diameter and isO078500100041 arranged in two cones each of 16 individual counters. O078500100042 The stop counters are divided into the inner part O078500100043 (quirl counter with 96 channels in 3 layers), the ringO078500100044 counter with 192 channels in 3 layers and the barrel O078500100045 counter with 192 channels. The high granularity of theO078500100046 stop scintillators results in a resolution for the O078500100047 azimuthal angle of 2-4 degree and for the polar angle O078500100048 of typically 0.5 degree. O078500100049 METHOD (EXTB) The external proton beam with a diameter of 1-2 O078500100050 mm. O078500100051 (TOF) The time of flight is measured with a resolution O078500100052 of 1% of the typical time of flight for protons of the O078500100053 pp > pp+eta reaction close to the threshold. This timeO078500100054 resolution corresponds to a momentum resolution for O078500100055 these protons of delta-P/P = 3%. O078500100056 ANALYSIS The ETA is reconstructed from the tracks of both O078500100057 protons. For each track the particle momentum is O078500100058 calculated from the time of flight and the measured O078500100059 directions with the mass of the proton assumed. The O078500100060 missing mass is calculated from momentum and energy O078500100061 conservation O078500100062 ADD-RES (ANGD) For the relative momentum of the protons in the O078500100063 C.-M. System. O078500100064 Squared proton-proton invariant-mass distribution. O078500100065 Squared proton ETA invariant-mass distribution. O078500100066 HISTORY (20040115C) O078500100067 (20040421U) Last checking has been done. O078500100068 (20120520U) SD: COSY collaboration was added to O078500100069 AUTHOR's list O078500100070 ENDBIB 68 0 O078500100071 NOCOMMON 0 0 O078500100072 ENDSUBENT 71 0 O078500199999 SUBENT O0785002 20040421 0000O078500200001 BIB 6 19 O078500200002 REACTION (1-H-1(P,2P)0-ET-0,,DA) O078500200003 REL-REF (R,,H.CALEN+,J,PL/B,366,39,1996) Total ETA production O078500200004 cross section has been taken from the paper. O078500200005 (D,,H.CALEN+,J,PL/B,458,190,1999) The results of O078500200006 CELSIUM. O078500200007 PART-DET (P) O078500200008 ERR-ANALYS (ERR-S) A statistical uncertainty O078500200009 (ERR-1) The systematic error is composed of a constantO078500200010 term due to possible angular-dependent detector and O078500200011 reconstruction inefficiencies(+/- 5%) and of a term O078500200012 which is proportional to the width of the ETA signal inO078500200013 the missing mass, in order to reflect the error due to O078500200014 the separation of the signal from background (+/- 2% *O078500200015 FWHM (MeV/c**2)). O078500200016 MISC-COL (MISC) An excess energy of p-p-ETA system. O078500200017 COMMENT -By authors. The angular distributions are normalized O078500200018 to the total cross-sections of 2.11 microbarn at excessO078500200019 energy = 15 MeV and 4.92 microbarn at excess energy = O078500200020 41 MeV. O078500200021 ENDBIB 19 0 O078500200022 NOCOMMON 0 0 O078500200023 DATA 6 20 O078500200024 EN COS-CM DATA ERR-S ERR-1 MISC O078500200025 MEV NO-DIM MU-B/SR MU-B/SR MU-B/SR MEV O078500200026 1293.53 -0.9 0.168 0.007 0.018 15.O078500200027 1293.53 -0.7 0.163 0.006 0.015 15.O078500200028 1293.53 -0.5 0.172 0.006 0.013 15.O078500200029 1293.53 -0.3 0.173 0.005 0.011 15.O078500200030 1293.53 -0.1 0.173 0.005 0.011 15.O078500200031 1293.53 0.1 0.168 0.005 0.01 15.O078500200032 1293.53 0.3 0.159 0.005 0.009 15.O078500200033 1293.53 0.5 0.165 0.006 0.01 15.O078500200034 1293.53 0.7 0.17 0.006 0.012 15.O078500200035 1293.53 0.9 0.167 0.006 0.013 15.O078500200036 1361.8 -0.9 0.366 0.033 0.068 41.O078500200037 1361.8 -0.7 0.383 0.033 0.064 41.O078500200038 1361.8 -0.5 0.402 0.032 0.055 41.O078500200039 1361.8 -0.3 0.357 0.03 0.04 41.O078500200040 1361.8 -0.1 0.376 0.026 0.035 41.O078500200041 1361.8 0.1 0.432 0.024 0.036 41.O078500200042 1361.8 0.3 0.379 0.027 0.03 41.O078500200043 1361.8 0.5 0.398 0.027 0.034 41.O078500200044 1361.8 0.7 0.436 0.032 0.042 41.O078500200045 1361.8 0.9 0.387 0.029 0.045 41.O078500200046 ENDDATA 22 0 O078500200047 ENDSUBENT 46 0 O078500299999 ENDENTRY 2 0 O078599999999