A CsI(Tl) hodoscope on CSHINE for Bremsstrahlung -rays in heavy ion reactions

Bremsstrahlung gamma production in heavy ion reactions at Fermi energies carries important physical information including the nuclear symmetry energy at supra-saturation densities. In order to detect the high energy Bremsstrahlung ??????rays, a hodoscope consisting of 15 CsI(Tl) crystals read out by photo multiplier tubes has been built, tested and operated in experiment. The resolution, efficiency and linear response of the units to ??????rays have been studied using radioactive source and (p, ??????) reactions. The inherent energy resolution of 1.6% + 2%/??????1/2 ??????is obtained. Reconstruction method has been established through Geant 4 simulations, reproducing the experimental results where comparison can be made. Using the reconstruction method developed, the whole efficiency of the hodoscope is about 2.6 x 10-4 against the 4 ?????? emissions at the target position, exhibiting insignificant dependence on the energy of incident ??????rays above 20 MeV. The hodoscope is operated in the experiment of 86Kr + 124Sn at 25 MeV/u, and a full ??????energy spectrum up to 80 MeV has been obtained.