B(GT)strength fromβ-decay measurements and inferred shape mixing inKr

Abstract

A total absorption spectrometer, dedicated to the study of very short-lived atomic species, has been built and installed at the CERN/ISOLDE mass separator. The ␤ decay of the neutron-deficient 74 Kr nucleus has been studied using this new device. The Gamow-Teller strength distribution has been observed over most of the Q EC window, and a total strength of 0.69͑3͒ g A 2 /4 has been measured for states with excitation energy below 3 MeV. Shape mixing in the 74 Kr ground state is inferred from a comparison of the experimental strength distribution with self-consistent, deformed, quasiparticle-random-phase-approximation calculations.

Simultaneous investigation of the T=1(Jπ=0+) and T=0(J

“…Experimentally, the picture of shape-related phenomena in the Se (Z=34) isotopic chain is more ambiguous than for the heavier Kr (Z=36) isotopes [15][16][17][18][19][20]. It has been shown that the ground states of the even-even 74−82 Se are prolate-deformed [21,22].…”

Radioactive decay data: powerful aids in medical diagnosis and therapy, analytical science and other applications

“…Total Absorption Gamma-ray Spectroscopy (TAGS) has been successfully used to determine the β − strength functions of a significant number of complex decay schemes [37][38][39][40][41] on the basis of calculations involving the data derived from 4π γ-ray spectroscopy. Normally, the main spectrometer consists of a substantial well-type NaI(Tl) detector in which the γ -ray emitting source is contained, along with an auxiliary NaI(Tl) detector that fits into and closes the well to achieve an approximately 97% 4π solid-angle geometry.…”

“…Good overall detection efficiency and energy resolution are required, along with a sound spectral understanding in order to disentangle the decay components from each other and any background activity. TAGS has proved to be of importance in the development of a more correct and comprehensive understanding of the nucleus, reaching beyond some of the specific limitations of γ singles and coincidence measurements [39,40]. Furthermore, TAGS studies have been used to determine the average β − and γ energies of particular fission produces, aiding considerably in calculations of the decay heat emitted by irradiated reactor fuel [38,41] -see also Sect.…”

“…Faced with such serious uncertainties in the long-term stability of argon content for sample analysis and the need to undertake two separate analytical procedures in order to measure parent potassium and daughter argon, research scientists have increasingly preferred to date their samples of interest by the more sophisticated quantification of 40 Ar/ 39 Ar ratios that arise within samples irradiated in a well-defined fast-neutron flux. Within the carefully controlled conditions of a suitable nuclear reactor, 39 Ar can only be produced via the 39 K(n f , p) 39 Ar reaction, which is dependent upon the amount of 39 K within the irradiated sample, length of irradiation, neutron-flux density and neutron-capture cross section of 39 K, whereas the 40 Ar content arises from the natural EC decay of 40 K. Massspectrometric measurements can be made more precisely on isotopes of the same element (argon), although corrections may still be required to allow for the presence of atmospheric argon and interference from other reactor-produced isotopes. Under these better considered circumstances, studies of 40 Ar/ 39 Ar ratios are more commonly undertaken in preference to 40 Ar/ 38 Ar ratio measurements.…”

“…Within the carefully controlled conditions of a suitable nuclear reactor, 39 Ar can only be produced via the 39 K(n f , p) 39 Ar reaction, which is dependent upon the amount of 39 K within the irradiated sample, length of irradiation, neutron-flux density and neutron-capture cross section of 39 K, whereas the 40 Ar content arises from the natural EC decay of 40 K. Massspectrometric measurements can be made more precisely on isotopes of the same element (argon), although corrections may still be required to allow for the presence of atmospheric argon and interference from other reactor-produced isotopes. Under these better considered circumstances, studies of 40 Ar/ 39 Ar ratios are more commonly undertaken in preference to 40 Ar/ 38 Ar ratio measurements. Other debatable assumptions and various analytical difficulties also exist within the other systems listed in Table 5 [120][121][122], although they will not be considered further in this particular review.…”