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The first phase of the National Array of Neutron Detectors (NAND) consisting of 26 neutron detectors has been commissioned at the Inter University Accelerator Centre (IUAC), New Delhi. The motivation behind setting up of such a detector system is the need for more accurate and efficient study of reaction mechanisms in the projectile energy range of 5–8 MeV/n using heavy ion beams from a 15 UD Pelletron and an upgraded LINAC booster facility at IUAC. The above detector array can be used for inclusive as well as exclusive measurements of reaction products of which at least one product is a neutron. While inclusive measurements can be made using only the neutron detectors along with the time of flight technique and a pulsed beam, exclusive measurements can be performed by detecting neutrons in coincidence with charged particles and/or fission fragments detected with ancillary detectors. The array can also be used for neutron tagged gamma-ray spectroscopy in (HI, xn) reactions by detecting gamma-rays in coincidence with the neutrons in a compact geometrical configuration. The various features and the performance of the different aspects of the array are described in the present paper. [ABSTRACT FROM AUTHOR]

Abstract: Inclusive and exclusive neutron evaporation spectra have been studied from the fusion reactions at 80 MeV 12C on 46Ti and 131 MeV 31P on 27Al, populating the compound nucleus 58Ni at the excitation energy of 79.5 MeV but in different angular momentum ranges. The evaporation residues 53Fe, 55Fe and 56Co were identified by their characteristic γ-rays. The measured energy spectra of evaporated neutrons were compared with the predictions from statistical-model calculations. In case of the asymmetric system 12C + 46Ti, the neutron spectra are well reproduced, when compared with the results from statistical-model calculations with level density parameter . On the contrary, the experimental spectra for the symmetric system 31P + 27Al are found to be harder than the theoretical predictions with . In this case, a lower value of the level density parameter seems to be required to reproduce the experimental results. The dependence of the energy spectra on the entrance channel is taken as an indication that, in case of the symmetric system, the neutrons are in part emitted from a temperature equilibrated di-nuclear complex at a higher temperature before the formation of the compound nucleus. [Copyright &y& Elsevier]

Abstract: The low energy high purity germanium (HPGe) detectors are being increasingly used for the quantitative estimation of elements using X-ray spectrometric techniques. The softwares used for quantitative estimation normally evaluate model based efficiency of detector using manufacturer supplied detector physical parameters. The present work shows that the manufacturer supplied detector parameters for low energy HPGe detectors need to be verified by comparing model based efficiency with the experimental ones. This is particularly crucial for detectors with ion implanted P type contacts. [Copyright &y& Elsevier]

Abstract: L x-ray production cross sections have been measured for thin solid targets (∼50μg/cm2) of 57La, 58Ce, 60Nd and 62Sm for 35–60MeV C4+ and O5+ ions. There is an increase in these cross sections with the increasing projectile energy and the ratio of its atomic number to the atomic number of the target nucleus (Z 1/Z 2). The measured L x-ray production cross sections have been compared with the predicted values of the first Born approximation (FBA) and of the ECPSSR theory that accounts for the projectile energy loss and Coulomb deflection and the perturbed stationary-state and relativistic nature of the L-shell. For C4+ ions, there is a reasonable agreement with the ECPSSR predicted values for the higher Z elements (Nd and Sm), while for the lower Z elements (La and Ce), the FBA is in a better accord with the data. For O5+ ions, the FBA gives a better agreement for all the elements than the ECPSSR theory. [Copyright &y& Elsevier]

As part of the study of trace elemental analysis of ancient Indian coins, twenty-five coins belonging to medieval period (11th-14th century A.D.) and fifty-nine coins belonging to Kusanas (78-250 A.D.) from India have been analyzed using Proton Induced X-ray Emission (PIXE) technique. The elements S, Ca, Fe, Cu, Ag, Sn, Pb were detected in 14th-14th century A.D. coins while elements namely S, Cl, K, Ca, Ti, Cr, Mn, Fe, Ni, Cu. As and Zn were detected in most of the Kusanas coins. Based on the elemental analysis different hypotheses put forward in the earlier literature were examined. The presence of Pb determined in medieval period coins does not rule out the utilization of local source of silver extracted from argentiferous galena instead of the Faranial mines of Afghanistan as normally accepted. From the consistent concentration of Ag in these coins despite the change of Kingdoms, it is confirmed that beside the rulers the commercial communities had a great influence in the currency of medieval period. This is the first attempt where reasonable number of ancient coins belonging to different periods were analysed by modern non destructive multi-elemental technique such as PIXE and has put the importance of the elemental analysis of ancient Indian coins in the proper perspective. [ABSTRACT FROM AUTHOR]