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High spin states in 104Ag were populated via heavy-ion (32S) induced fusion evaporation reaction at a beam energy of 110 MeV. The de-exciting γ-rays were detected by 18 Compton suppressed HPGe clover detectors, placed in different (θ, φ) angles. Spin of several excited states were assigned firmly from the present angular correlation measurement.

International audience; Doppler Shift Attenuation Method (DSAM) analysis of excited-state lifetimes normally employs thin production targets mounted on a thick stopper foil (“backing”) serving to slow down and stop the recoiling nuclei of interest in a well-defined manner. Use of a thick, homogeneous production target leads to a more complex analysis as it results in a substantial decrease in the energy of the incident projectile which traverses the target with an associated change in the production cross section of the residues as a function of penetration depth. Here, a DSAM lifetime analysis using a thick homogeneous target has been verified using the Doppler broadened lineshapes of γ rays following the decay of highly excited states in the semi-magic (N = 50) nucleus 94Ru. Lifetimes of excited states in the 94Ru nucleus have been obtained using a modified version of the LINESHAPE package from the Doppler broadened lineshapes resulting from the emission of the γ rays, while the residual nuclei were slowing down in the thick (6 mg/cm2) metallic 58Ni target. The results have been validated by comparison with a previous measurement using a different (RDDS) technique.

High purity n-type silicon single crystal with resistivity in the order of 4000 Ω cm has been irradiated with high-energy oxygen ions at room temperature up to a fluence of 5E15 ions/cm2. The energy of the beam was varied from 3 to 140 MeV using a rotating degrader to achieve a depthwise near-uniform implantation profile. Radiation induced defects and their dynamics have been studied using positron annihilation spectroscopy along with isochronal annealing up to 700 °C in steps of 50 °C for 30 min. After annealing the sample at 200 °C for 30 min, formation of silicon tetravacancies has been noticed. The formation of the tetravacancies was found to be due to agglomeration of divacancies present in the irradiated sample. An experimentally obtained positron lifetime value of 338±10 ps has been reported for silicon tetravacancies, which has a very close agreement with the value obtained from recent theoretical calculations. The tetravacancies were found to dissociate into trivacancy clusters upon further annealing. The trivacancies thus obtained were observed to agglomerate beyond 400 °C to form larger defect clusters. Finally, all the defects were found to anneal out after annealing the sample at 650 °C.

Two interacting, strongly-deformed triaxial (TSD) bands have been identified in the Z = 69 nucleus ^{163}Tm. This is the first time that interacting TSD bands have been observed in an element other than the Z = 71 Lu nuclei, where wobbling bands have been previously identified. The observed TSD bands in ^{163}Tm appear to be associated with particle-hole excitations, rather than wobbling. Tilted-Axis Cranking (TAC) calculations reproduce all experimental observables of these bands reasonably well and also provide an explanation for the presence of wobbling bands in the Lu nuclei, and their absence in the Tm isotopes., Comment: 13 pages, 7 figures

A new analytical method for estimation and subsequent subtraction of random coincidences has been developed. It utilizes the knowledge of the counts in the main diagonal of a background-subtracted symmetric data set for the estimation of the events originating from random coincidences. This procedure has been successfully applied to several data sets. It could be a valuable tool for low-fold data sets, especially for low-cross-section events.

Inter University Consortium for DAE Facilities Silicon surface barrier (SSB) detectors have been fabricated with oxygen enriched, high-resistivity, detector grade, n-type FZ silicon. Oxygen enrichment of the wafer was done by high-energy (140 MeV) oxygen ion implantation. Annealing of the irradiated silicon wafer was done to minimize the irradiation-induced defect concentration. Positron annihilation lifetime studies were used to select the annealing temperature. A comparative study was carried out among various SSB detectors made from as-grown, as-irradiated and annealed silicon wafers. Detector made from the annealed wafer worked satisfactorily and its performance was comparable with that of a detector made from as-grown crystal.

Detector grade n-type float-zone silicon irradiated with 140 MeV O 6+ ions to a dose of 5×1015 particles/cm2 was studied by positron annihilation spectroscopy. Vacancy clusters containing five vacancies were detected in the irradiated sample. Isochronal annealing studies of the irradiated sample reveal the dissociation of five-vacancy clusters and formation of vacancy agglomerates V3, V6 and vacancy-oxygen complexes in the temperature range 250-500 °C. The vacancy-oxygen complexes dissociate at 550 °C and released vacancies agglomerate around 600 °C to form voids comprising 10 vacancies. In the temperature range 600-700 °C, the voids dissociate and around 750 °C advanced vacancy-oxygen complexes VmOn (n>m) form. © 2005 Elsevier B.V. All rights reserved.

Angular distributions of elastic scattering and inelastic scattering from 2+1 state are measured for 16O+142,144,146Nd systems at several energies in the vicinity of the Coulomb barrier. The angular distributions are systematically analyzed in coupled channel framework. Renormalized double folded real optical and coupling potentials with DDM3Y interaction have been used in the calculation. Relevant nuclear densities needed to generate the potentials are derived from shell model wavefunctions. A truncated shell model calculation has been performed and the calculated energy levels are compared with the experimental ones. To simulate the absorption, a ‘hybrid’ approach is adopted. The contribution to the imaginary potential of couplings to the inelastic channels, other than the 2+1 target excitation channel, is calculated in the Feshbach formalism. This calculated imaginary potential along with a short ranged volume Woods–Saxon potential to simulate the absorption in fusion channel reproduces the angular distributions for 16O+146Nd quite well. But for 16O+142,144Nd systems additional surface absorption is found to be necessary to fit the angular distribution data. The variations of this additional absorption term with incident energy and the mass of the target are explored.

Particle-induced X-ray emission (PIXE) analysis was employed in the present study to investigate the chemopreventive potential of vanadium in influencing trace elemental profile and antioxidant status in chemical carcinogenesis. The elements with Za 15‐40 were studied. Data reveal remarkable alterations in elemental composition in the hepatic tissue of diethylnitrosamine (DENA)-induced Sprague‐Dawley male rats (intraperitoneal (ip) dose: 200 mg/kg body weight) after four weeks of induction. Several elements like Mn, Cu, Zn, Rb showed large depletion while other elements like Fe, Ca, K, Br showed large enhancement in comparison to that of the normal control animals. These elements compete for binding sites in the cell, change its enzymatic activity and exert direct or indirect action on the carcinogenic process. Supplementary vanadium (0.5 ppm ad libitum in drinking water) has shown eAective modulation by alteration in the concentration of trace elements in the tumorigenic tissue (P < 0:001‐0:005). Data reflect a definite correlation between elemental composition, antioxidant status in the initiation phase of carcinogenesis and the period of exposure to vanadium. The possibility of selecting vanadium as a therapeutic agent for chemoprevention is discussed in the light of its influence in maintaining trace elemental homeostasis, a parameter of importance in cancer prevention research. ” 2000 Elsevier Science B.V. All rights reserved.

High-resistivity detector-grade p-type silicon wafers have been implanted with swift oxygen (O6+) ions under two different conditions. One of the wafers was implanted effectively with a pulsed beam of varied energy (3-140MeV) to a total fluence of 5 × 1015ionscm-2, resulting in a depth-wise near-uniform implantation profile. The other wafer was directly irradiated with a 140MeV steady oxygen beam to the same fluence. Radiation-induced defects produced in the samples and their isochronal annealing behaviours were studied by positron annihilation lifetime spectroscopy and Doppler broadening of positron annihilation radiation measurements. The lifetime spectra of the irradiated samples were fitted with three lifetimes. Trapping model analysis was carried out with the de-convoluted lifetimes to characterize the defect states. The defect-related lifetime τ2 in both the irradiated samples was found to be due to an admixture of divacancy (V 2) and divacancy-oxygen (V2O) complexes. A marked difference in the defect reordering process has been observed between the two samples, which is explained by taking into account the effect of injection annealing by minority carriers which are produced by the energetic beam prior to forming displacement damage. © IOP Publishing Ltd.