Speaker
Description
Evaporated light particles carry information of the temperature, angular momentum, deformation, and lifetime of the emitting source. Earlier studies have shown that neutron, proton, and α-particle spectra may carry signatures of dynamical deformation, particularly when the formation and decay time scales of the composite system are comparable. In particular, the slopes of the emitted particle spectra, especially the high energy components are modified due to changes in these parameters, making exclusive neutron, proton, and α-particle measurements a useful probe of compound-nucleus formation and dynamical evolution. Motivated by these observations, we have measured exclusive neutron and charged-particle spectra at the near-barrier energies for 48Ti + 48Ti reaction, leading to the formation of the compound nucleus 96Ru∗.
The experiment was performed at the National Array of Neutron Detectors (NAND) facility at the Inter-University Accelerator Centre, New Delhi, using beams from the 15 UD Pelletron accelerator. The experiment was performed at 130 MeV, 140 MeV, and 150 MeV energies. Neutrons were detected with sixteen in-plane BC501A organic liquid scintillator detectors, while protons and α particles were measured using a CsI(Tl) detector array placed inside the NAND scattering chamber. Two Multi-Wire Proportional Counters positioned at forward angles were used to detect evaporation residues, enabling residue-gated exclusive spectra for neutrons and charged particles. The measured spectra were analyzed within the statistical-model framework using the CASCADE code, with complementary calculations from PACE and HICOL to estimate the decay and formation time scales. The HICOL calculations give a compound-system formation time of 5.43×10−21 s, while the PACE calculations yield a decay time of 6.40×10−21 s. Since these two time scales are of the same order, the present near-barrier data do not show a strong signature of fusion hindrance within the measured energy range. The observed particle spectra are consistent with compound-nucleus decay as predicted by the statistical model. In addition, time-dependent mean-field calculations with the Sky3D code are being carried out to reproduce the entrance-channel density evolution and to investigate the dynamical formation and deformation of the composite 96Ru∗ system. A detailed discussion of the measured neutron and charged-particle spectra, statistical-model comparisons, and dynamical evolution of the composite system will be presented at the conference.