Maitreyee Nandy

Sequential separation of carrier free radioisotopes of rhodium, silver and cadmium produced in α-particle activated palladium by TOA

Abstract Carrier free radioisotopes of rhodium, silver and cadmium, 101,105,106mRh, 103,104,105,106,110m,112Ag and 104,105,107,109,111mCd, respectively, were produced simultaneously by α-particle activation of metallic palladium. The radioisotopes produced were separated by LLX using TOA as a liquid anion exchanger. The presence of the various radionuclides in the activated target matrix and their purity at various stages of separation were verified by taking recourse to γ-ray spectrometry.

Sequential separation by HDEHP of carrier-free101,105,106Rh,103,104,105,106,110,112Ag and104,105,107,109,111Cd produced in alpha-particle activated palladium

Carrier free101,105,106Rh,103,104,105,106,110,112Ag and104,105,107,109,111Cd radioisotopes were produced simultaneously by α-particle irradiation of palladium target material in a variable energy cyclotron. The radioisotopes produced were extracted and separated from the activated target by LLX using HDEHP as liquid cation exchanger. With the help of γ-ray spectrometry the presence of several radioisotopes in the activated target matrix and their purity at each step of the separation was confirmed.

Directional distribution of the ambient neutron dose equivalent from 145-MeV 19F projectiles incident on thick Al target

The directional distribution of the ambient neutron dose equivalent from 145-MeV (19)F projectiles bombarding a thick aluminium target is measured and analysed. The measurements are carried out with a commercially available dose equivalent meter at 0°, 30°, 60° and 90° with respect to the beam direction. The experimental results are compared with calculated doses from EMPIRE nuclear reaction code and different empirical formulations proposed by others. The results are also compared with the measured data obtained from an earlier experiment at a lower projectile energy of 110 MeV for the same target-projectile combination.

An empirical fit to estimated neutron emission cross sections from proton induced reactions

Neutron emission cross section for various elements from9Be to209Bi have been calculated using the hybrid model code ALICE-91 for proton induced reactions in the energy range 25 MeV to 105 Me V. An empirical expression relating neutron emission cross section to target mass number and incident proton energy has been obtained. The simple expression reduces the computation time significantly. The trend in the variation of neutron emission cross sections with respect to the target mass number and incident proton energy has been discussed within the framework of the model used.

Direction distribution of ambient neutron dose equivalent from 20 MeV protons incident on thick Be and Cu targets

Ambient neutron dose equivalent from 20 MeV protons incident on thick Be and Cu targets are measured at 0 degrees, 30 degrees, 60 degrees and 90 degrees with respect to the beam direction using a conventional dose equivalent meter. The neutron spectra calculated using nuclear reaction model codes ALICE, PRECO and earlier reported empirical expressions are converted to the ambient dose equivalent using the ICRP fluence-to-dose conversion coefficients and are compared with the measured values. The experimental energy spectra reported in the literature for 19.08 MeV protons incident on a thick Be target are also converted to ambient neutron dose equivalent and are compared with the present experimental results. It is observed that the values estimated from the neutron spectra obtained from the nuclear reaction codes are unable to predict the measured values. The results obtained from the reported experimental energy spectra compare well with the results obtained here. An empirical relation that was used to calculate the directional dependence of the measured neutron dose equivalent from heavy ion-induced reactions is used in this study to check its effectiveness for proton-induced reactions.

Excitation function measurement and reaction mechanism analysis for alpha-induced reactions on

Excitation functions have been measured for and produced by -particle-induced reactions on in the incident energy range 34-50 MeV. The excitation functions of these nuclei and those of , reported earlier, are analysed in terms of direct, pre-equilibrium and evaporation emissions. The two most commonly used models of pre-equilibrium reactions, the exciton and the hybrid models, have both been used and compared. The choice of the initial exciton number, the role of the pre-equilibrium cluster and multiple nucleon emissions have been investigated. The direct emission of clusters are found to significantly affect the excitation functions of and Au isotopes.

Calculation of excitation functions of nuclides produced in proton induced reactions on NatSi.

Excitation functions of several nuclides from p+ NatSi reactions in the incident energy range of 20-110 MeV have been calculated using the hybrid model nuclear reaction code ALICE. Comparisons with experimental data have been made to select proper input options of the code. These data are useful to estimate possible damage in devices containing Si, from the bombardment of solar or accelerator produced protons.

NEUTRON ACTIVATION ANALYSIS OF NOBLE AND PLATINUM GROUP METALS IN THE PROTEROZOIC DALMA ROCKS OF EASTERN INDIA

Abstract The Proterozoic Dalma volcanic belt in the Singhbhum Orogen represents the main zone of axial rifting along which lavas of ultrabasic, basic and acidic compositions, pyroclastics and ashes were extruded spasmodically carrying the mineralizing elements from the subcrustal magmatic chamber. Neutron activation analysis, supported by AAS studies of the metamorphosed volcanic and sedimentary rocks in the Belpahari-Kankrajhor sector (22°37′N, 86°41′E) of the Eastern Dalma belt in the district of Midnapore, West Bengal, India, has revealed the existence of platinum, palladium, silver, gold and iridium at concentrations of 2.1, 3.3, 1.92 ppm, 2.65 and 0.12 ppb respectively. Prior to neutron activation, the noble and platinum group metals have been preconcentrated in lead buttons through fire assay and the activated samples have been studied by gamma-ray spectrometry. The anomaly in the existence of the noble and platinum group metals in the relevant rocks deserves detailed geological and exploratory study.

Neutron emission and dose distribution from natural carbon irradiated with a 12 MeV amu−1 12C5+ ion beam

Measured neutron energy distribution emitted from a thick stopping target of natural carbon at 0°, 30°, 60° and 90° from nuclear reactions caused by 12 MeV amu-1 incident 12C5+ ions were converted to energy differential and total neutron absorbed dose as well as ambient dose equivalent H *(10) using the fluence-to-dose conversion coefficients provided by the ICRP. Theoretical estimates were obtained using the Monte Carlo nuclear reaction model code PACE and a few existing empirical formulations for comparison. Results from the PACE code showed an underestimation of the high-energy part of energy differential dose distributions at forward angles whereas the empirical formulation by Clapier and Zaidins (1983 Nucl. Instrum. Methods 217 489-94) approximated the energy integrated angular distribution of H *(10) satisfactorily. Using the measured data, the neutron doses received by some vital human organs were estimated for anterior-posterior exposure. The estimated energy-averaged quality factors were found to vary for different organs from about 7 to about 13. Emitted neutrons having energies above 20 MeV were found to contribute about 20% of the total dose at 0° while at 90° the contribution was reduced to about 2%.

Quantum molecular dynamics approach to estimate spallation yield fromp +208Pb reaction at 800 MeV

The spallation yield of neutrons and other mass fragments produced in 800 MeV proton induced reaction on208Pb have been calculated in the framework of quantum molecular dynamics (QMD) model. The energy spectra and angular distribution have been calculated. Also, multiplicity distributions of the emitted neutrons and kinetic energy carried away by them have been estimated and compared with the available experimental data. The agreement is satisfactory. A major contribution to the neutron emission comes from statistical decay of the fragments. For mass and charge distributions of spallation products the QMD process gives rise to target-like and projectile-like fragments only.