When a positron annihilates, two gamma photons are created with orthogonal polarizations. It is possible to use coincidence measurements where both photons undergo Compton scattering to estimate their initial relative polarization orientation. This information is of great interest in gamma imaging systems, such as Positron Emission Tomography, where it may be used as an additional tool to distinguish true coincidence events from scatter and random background. The successful utilization of this principle critically depends on the detector’s angular and energy resolution, which determine its polarimetric performance. In this study, we use Monte Carlo simulations based on the Geant4 toolkit to model two multi-pixel detector configurations identified as prospective for the measurement of gamma-ray polarization in PET. One is based on 2 mm × 2 mm × 20 mm LYSO scintillators and the other is based on 3 mm × 3 mm × 20 mm GAGG scintillators. Each configuration has a pair of modules, each consisting of 64 crystals set up in a single 8 × 8 matrix, where both the recoil electron and the Compton-scattered photon are absorbed. We simulate positron annihilation by generating two back-to-back gamma photons of 511 keV with orthogonal polarizations. The Compton scattering is successfully identified and the modulation of the azimuthal angle difference is clearly observed. The configuration based on GAGG crystals demonstrates slightly better polarimetric performance than the one based on LYSO crystals, reflected in the more pronounced azimuthal modulation.

Excitation functions for the 11 evaporation residues populated through complete and/or incomplete fusion in ${}^{16}\mathrm{O}+{}^{124}\mathrm{Sn}$ system at low projectile energies $\approx 3-7\mathrm{MeV}/\mathrm{nucleon}$ have been measured. Recoil catcher activation technique followed by offline $\gamma$-ray spectrometry has been employed. Some of the evaporation residues are found to have contributions from precursor decays. The precursor contributions have been separated out from the measured cumulative cross-sections of evaporation residues. Independent cross-sections are compared with statistical model code PACE-4 predictions. The evaporation residues produced through $xn$ and pxn channels are found to be well reproduced with the PACE-4 predictions after subtraction of precursor decay contributions. A substantial enhancement in the measured excitation functions over their theoretical predictions for the evaporation residues produced in $\alpha$-emitting channels has been observed, which is attributed to the presence of incomplete fusion of projectile with target at these low energies. The present study shows that the incomplete fusion and the break-up probability of the incident ${}^{16}\mathrm{O}$ into $\alpha$ clusters (i.e., break-up of ${}^{16}\mathrm{O}$ into ${}^{12}\mathrm{C}+\alpha$ and/or ${}^8\mathrm{Be}+{}^8\mathrm{Be}$) increases with projectile energy. The present data suggests that the deformation of target is highlighting the important role to affect the ICF reactions independently with different projectiles. The comparison of the present study with literature data also shows that the ICF probability depends on various entrance channel parameters, namely, projectile energy, entrance channel mass-asymmetry, $\alpha \text{−}Q$ value, Coulomb factor $\left(Z_{\mathrm{P}}{Z}_{\mathrm{T}}\right)$, deformation parameter (${\beta }_2$), and their combinations. Moreover, the combined parameters $Z_{\mathrm{P}}{Z}_{\mathrm{T}}·{\beta }_2$ and ${\mu }_{\mathrm{EC}}^{\mathrm{AS}}·{\beta }_2$ are not found suitable to explain whole ICF characteristics, particularly for spherical and slightly deformed targets. On the other hand, the combined parameter $Z_{\mathrm{P}}{Z}_{\mathrm{T}}·{\mu }_{\mathrm{EC}}^{\mathrm{AS}}$ has been found to explain more precisely the ICF dynamics as compared to other single and combined entrance channel parameters.

The production cross sections for the medical isotope ${}^{99}\mathrm{Mo}$ were measured using the ${}^{100}\mathrm{Mo}(n,2n)$ reaction at average neutron energies of $10.95\pm 0.45, 13.97\pm 0.68, 16.99\pm 0.53$, and $20.00\pm 0.58$ MeV using offline $\gamma$-ray spectroscopy. The neutron beam was generated using the ${}^{\mathrm{nat}}\mathrm{Li}(p,n)$ reaction at the 14UD BARC-TIFR Pelletron facility, Mumbai, India. The uncertainties in the measured data were calculated using covariance analysis. The experimental results were compared with the existing data libraries ENDF/B-VII.1, JENDL-4.0, JEFF-3.2, and CENDL-3.1. The present results were also reproduced and compared with the theoretical nuclear model codes talys-1.9 and alice-2017 using different input descriptions. A modified set of parameters were also used in talys-1.9 to fit the existing data more accurately. The present findings show a good agreement with the theoretical predictions and with the existing experimental results from the different data libraries. In addition to this, a comparative study have also been performed between the literature data of $(n,p), (n,2n)$, and $(n,\alpha )$ reaction cross sections at 14.5 MeV using various systematic formulas. The outcomes of the present work are important for the advancement of medical accelerators, dosimetry, and fast reactor systems.