Particle gamma correlations in ~(12)C measured with the CsI(Tl) based detector array CHIMERA

摘要

The gamma decay of the first excited 4.44 MeV 2+level of ~(12)C populated by inelastic scattering of proton and ~(16)O beams at various energies was studied in order to test γ-ray detection efficiency and the quality of angular distribution information given by the CsI(Tl) detectors of the 4π CHIMERA array. The γ-decay was measured in coincidence with ejectile scattered particles in an approximately 4π geometry allowing to extract the angular distribution in the reference frame of recoiling ~(16)C target The typical sin~2 (2θ) behavior of angular distribution was observed in the case of ~(16)O beam. Besides that, for the proton beam, in order to explain the observed distribution, the addition of an incoherent flat contribution was required. This latter is the effect of proton spin flip events allowing the population of M= ± 1 magnetic substates, that is not possible in reactions induced by ~(16)O beam. A comparison with previously collected data, obtained measuring only in and out of plane proton-γ-ray coincidences, confirms the good quality of the angular distribution information given by the apparatus. Possible applications with radioactive beams are outlined.