Study of the Bremsstrahlung radiation in the quasi-free np->np gamma reaction.

J.Przerwa for the COSY-11-Collaboration
Institute of Physics, Jagellonian University, Cracow, PL-30-059, Poland

Using a deuteron beam and a proton target the quasi-free np->np gamma reaction has been studied at the COSY-11 facility, an internal magnetic spectrometer system at the cooler synchrotron COSY in Jülich. Data have been taken at a beam momentum of 3.165 GeV/c close to the threshold of the dp->dp eta process. Events corresponding to the dp->pn gamma ps reaction have been identified by measuring the outgoing charged as well as neutron ejectiles. The fast protons are detected by means of drift chambers and scintillator hodoscopes and the slow spectator protonsare measured in a Si-pad arrangement close to the target. Neutrons and photons are registered in a scintillator/lead sandwich detector. The momentum vectors of the protons are reconstructed by tracking back the trajectories to the target point and the momentum of the neutron is calculated from the time-of-flight between target and neutron detector. For the calibration of the neutron detector the produced photons are used. The efficiency is determined by Monte Carlo studies supported by calibration measurements performed simultaneously to other reaction studies by selecting special reaction channels relevant for the neutron detector.

Results of the data analysis and the experimental techniques will be presented and discussed.

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