120242594
Weak-interaction strength from charge-exchange reactions versus {beta} decay in the A=40 isoquintet
We report a measurement of the Gamow-Teller (GT) strength distribution for {sup 40}Ar{yields}{sup 40}K using the 0 deg. (p,n) reaction. The measurement extends observed GT strength distribution in the A=40 system up to an excitation energy of {approx}8 MeV. In comparing our results with those from the {beta} decay of the isospin mirror nucleus {sup 40}Ti, we find that, within the excitation energy region probed by the {beta}-decay experiment, we observe a total GT strength that is in fair agreement with the {beta}-decay measurement. However, we find that the relative strength of the two strongest transitions differs by a factor of {approx}1.8 in comparing our results from (p,n) reactions with the {beta} decay of {sup 40}Ti. Using our results we present the neutrino-capture cross section for {sup 40}Ar.
118334834
Two experiments in neutrino physics: Double beta decay of cadmium-116 and the efficiency of an argon-40 neutrino detector
121755167
Electron capture decay of In-116 and nuclear structure of double beta decays
Quasiparticle-random-phase-approximation (QRPA) calculations of double {beta} decays have not been able to reproduce data in the A=100 system. We propose the A=116 system{emdash}because of its smaller deformation{emdash}as a simpler system to test QRPA calculations. We present results of two experiments we performed, which determine the electron-capture-decay branch of {sup 116}In to be (2.27{plus_minus}0.63){times}10{sup {minus}2}{percent}, from which we deduce logft=4.39{sub {minus}0.15}{sup +0.10}. We present QRPA calculations and compare their predictions to experimental data. Finally we use these calculations to predict the 2{nu} double-{beta}-decay rate of {sup 116}Cd to the ground and excited states of {sup 116}Sn. {copyright} {ital 1998} {ital The American Physical Society}
45540139
Precise study of the final-state continua in 8 Li and 8 B decays
We studied β-delayed singles-α spectra from 8Li and 8B decays with special emphasis on a careful calibration of the energy scale. 8Li and 8B activities were produced by 7Li(d, p) and 6Li(3He,n) reactions, respectively, and deposited in thin C foils. Delayed α’s were counted in thin, cooled Si detectors with small solid angles to reduce summing with β’s. The energy scale and detector response were calibrated with spectroscopic grade radioactive sources. We extracted the 8Li and 8B final-state continuum shapes from our spectra by using R-matrix analyses that included effects of lepton-recoil broadening and detector response. Our results are in excellent agreement with a recent measurement using 8B’s implanted in a Si counter and in good agreement with our reanalysis of the older Wilkinson-Alburger 8Li and 8B data, but disagree with a recent 8B experiment using a coincidence technique.
118982481
Neutron drip line in odd and even mass calcium and nickel nuclei
Neutron-rich Ca and Ni nuclei have been studied in a spherical relativistic mean-field formalism in coordinate space. A {delta} interaction has been adopted to treat the pairing correlations for the neutrons. Odd nuclei have been treated in the blocking approximation. The effect of the positive-energy continuum and the role of pairing in the stability of nuclei have been investigated by use of the resonant-BCS approach. In Ca isotopes, N=50 is no longer a magic number, whereas in Ni nuclei, a new magic number emerges at N=70. There is a remarkable difference in the relative positions of the drip lines for odd and even isotopes. In Ca isotopes, the last bound even and odd nuclei are found to be {sup 72}Ca and {sup 59}Ca, respectively. In Ni isotopes, the corresponding nuclei are {sup 98}Ni and {sup 97}Ni, respectively. The origin of this difference in relative positions of the drip line in even and odd isotopes in the two chains is traced to the difference in the single-particle level structures and consequent modification in the magic numbers in the two elements. Pairing interaction is seen to play a major role. The effect of the width of the resonance states on pairing hasmore » also been investigated.« less
3205210
Correction to Relativistic Mean Field binding energy and NpNn scheme
Abstract The differences between the experimental and Relativistic Mean Field binding energies have been calculated for a large number of even–even nuclei from A = 50 to 220. Excluding certain mass regions, the differences, after suitable corrections for particular isotope chains, are found to be proportional to the Casten factor P, chosen as a measure of n – p interaction strength in a nucleus. Results for even-Z odd-N nuclei are also seen to follow the same relation, if the odd–even mass difference is taken into account following the semiempirical formula. This indicates that the n – p interaction is the major contributor to the difference between the calculated and the experimental binding energies.
16195515
Microscopic calculation of half lives of spherical proton emitters
Abstract Half life values for proton radioactivity in nuclei have been calculated in the WKB approximation. The microscopic proton–nucleus potential has been obtained by folding the densities of daughter nuclei with two microscopic NN interactions, DDM3Y and JLM. The densities have been obtained in the Relativistic Mean Field approach in the spherical approximation using the force FSU Gold. No substantial modification of results has been observed if other common forces are employed. The calculated results for the decays from the ground state or the low-lying excited states in almost all the nuclei agree well with experimental measurements. Reasons for large deviations in a few cases have been discussed. Results in 109 I and 112,113 Cs show that the effect of deformation is small contrary to earlier calculations. Predictions for possible proton radioactivity have been made in two nuclei, 93 Ag and 97 In.
119481144
Role of pairing interaction in neutron rich odd and even Zr nuclei
Neutron rich Zr nuclei with number of neutrons between N=50 and 82 are investigated in the relativistic mean field approach in coordinate space. The resonant levels in the positive energy continuum have been explicitly included in the calculation. Odd nuclei have been treated in the blocking approximation. Our calculation indicates that the dripline for odd mass isotopes is far away from that for the even mass ones. Pairing interaction plays a significant role in stabilizing the even isotopes, thus extending the dripline for them.