Measurement of the high energy γ-rays from heavy ion reactions using ˇ Cerenkov detector

摘要: The energetic bremsstrahlung photons up to 100 MeV produced in heavy ion collisions can be used as a
sensitive probe to the short range correlation in atomic nuclei. The energy of the γ-rays can be measured
by collecting theˇCerenkov light in medium induced by the fast electrons generated in Compton scattering or
electromagnetic shower of the incident γ ray. Two types of detectors, based on pure water and lead glass as
the sensitive material respectively, are designed for the above purpose. The γ response and optical photon
propagation in detectors have been simulated based on the electromagnetic and optical processes in Geant4.
The inherent energy resolution of 0.022(4) + 0.51(2)/Eγ 1/2 for water and 0.0026(3) + 0.446(3)/Eγ 1/2 for
lead glass are obtained. The geometry size of lead glass and water are optimized at 30 × 30 × 30 cm3 and
60 × 60 × 120 cm3 , respectively, for detecting high energy γ-rays at 160 MeV. Hough transform method has
been applied to reconstruct the direction of the incident γ-rays, giving the ability to distinguish experimentally
the high-energy γ rays produced in the reactions on the target from the random background cosmic ray muons.