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  • Author or Editor: A. Ramaswami x
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Abstract  

The effects of gamma-irradiation at a dose range of 5-56 Mrad on the fission track registration efficiency of the Tuffak polycarbonate track detector from dry (K dry) as well as the solution media (K wet) are investigated. Fission tracks were recorded in the gamma-irradiated detectors along with the unirradiated ones by an electrodeposited source of 252Cf and also separately from a 252Cf solution. The fission track registration efficiencies for the irradiated detectors were determined in comparison with those of the unirradiated detectors. The results show that while the K dry values for the irradiated detectors decrease by about 2-10%, the corresponding K wet values decrease by about 3-20% as compared to unirradiated detectors . Further, the bulk etch rates were found to increase with the increase in gamma dose. The changes induced in the gamma-irradiated detectors as a function of dose have been studied also by thermogravimetry (TG).

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Abstract  

Effects induced by γ -irradiation in the dose range of 0-10 Mrad on Tuffak polycarbonate track detector films have been studied by thermogravimetry (TG). The samples were irradiated with 60Co γ -rays for doses of 3, 5 and 10 Mrad. The TG studies indicate that unirradiated and the γ -irradiated samples degrade in two steps. The kinetics of the two steps of degradation was also evaluated from the TG curves. Irradiation enhances the degradation rate and the effect increases further with increasing radiation dose. The activation energy values calculated for all the steps decrease on irradiation. A linear relationship observed between the decrease in activation energy and the dose received by the sample suggests the possibility of the use of Tuffak polycarbonate detector as γ dosimeter.

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Abstract  

Fission product yield studies in the reaction of 73,4 and 84.2 MeV12C with209Bi have been carried out using gamma-ray spectrometry. The cross sections for the production of fission products have been determined. The yield distribution of fission products is found to be symmetric and broad with FWHM around 25 mass units and peak near mass 107.7 and 107.0. The average number of neutrons emitted per fission have been found to be around 5.5 at 73.4 MeV and 7.1 at 84.2 MeV, respectively.

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Abstract  

The alpha-decay constant to fission cross section ratio for epi-cadmium neutron induced fission of 237Np, 241Am have been measured using solid state nuclear track detectors (SSNTDs). The measured values were (0.63±0.14).109 s-1.cm-2, (2.31±0.46).1012 s-1.cm-2 for 237Np and 241Am, respectively. The alpha to spontaneous fission branching ratio for 243Am was also measured to be (2.66±0.50).1010 using SSNTDs. These ratios are useful as signatures for the trace level identification of these actinides.

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Abstract  

Cumulative yields of short-lived xenon isotopes137,138,139Xe have been determined in the spontaneous fission of252Cf, using a fast radiochemical separation method followed by gamma spectrometry. Xenon-137 yield is reported for the first time. The measured cumulative yields are converted to chain yields assuming normal charge distribution systematics for comparision with the literature data.

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Abstract  

Formation cross sections of several fission products have been determined using recoil catcher technique followed by gamma-ray spectrometry in 12C induced fission of 232Th at E lab = 72 MeV, corresponding to E cm just above the Coulomb barrier. The measured formation cross sections were used to get the mass distribution by using known charge distribution systematic. Critical data analysis was carried out to look for the signatures of transfer induced fission. However, within the experimental uncertainty of about 10%, no clear indication of transfer induced fission could be seen at this energy level. The mass distribution shows a single peaked broad Gaussian distribution with the most probable mass of 119.5±1.1 and FWHM of 40.6 mass units. The total fission cross section computed from the mass distribution curve is 771±50 mb.

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Abstract  

A simple technique based on the measurement of the ratio of alpha-decay constant to neutron induced fission cross section for pure actinides using solid state nuclear track detectors (SSNTDs) is developed for the identification of the actinides in trace levels in pure solutions. The alpha-decay constant to fission cross section ratios for depleted U,238Pu and240Pu have been measured for the epicadmium neutron induced fission of these actinides. The measured values are (6.19±0.34)·106, (6.95±0.26)·1012, (2.12±0.95)·109 and (2.18±1.58)·1011 sec−1·cm−2, respectively. These ratios can be used for the trace level identification of pure actinides.

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Abstract  

Heavy ion activation of natural terbium foil with 75 MeV 12C6+ results in the formation of carrier-free lutetium isotopes, 165–167Lu, and their corresponding decay products, 165–167Yb and 165–167Tm, in the matrix. Carrier-free lutetium and ytterbium isotopes have been separated quantitatively from terbium bulk target matrix using HDEHP liquid cation exchanger. Radiochemically pure thulium radionuclides have been obtained after the decay of ytterbium radionuclides.

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Abstract  

Cumulative yields of short-lived/barium isotopes139, 141, 142Ba have been determined in the spontaneous fission of252Cf, using fast radiochemical separation and gamma-ray spectrometry.142Ba yield is reported for the first time. The measured cumulative yields are converted to chain yields, assuming normal charge distribution systematics for comparision with the literature data.

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Abstract  

Heavy-ion activation with ~55 MeV 11B beam on silver target leads to the production of carrier-free 111In, 116,117Te and 116,116m,117Sb radioisotopes in the target matrix. Liquid-liquid extraction, using Aliquat-336 and trioctylamine (TOA) as liquid anion exchangers in HNO3 and HCl medium, respectively, and di-(2-ethylhexyl)phosphoric acid (HDEHP) as liquid cation exchanger in ammoniacal medium was used to investigate the separation of the produced radioisotopes from the bulk target matrix.

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