Complex beta-decay schemes: Pandemonium lost and paradise regained

Firestone, R.B.

doi:10.1016/0370-2693(82)90408-7

Cited by 13 publications

(3 citation statements)

References 6 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In the interpretation presented, the 9/2-states represent lh,,, proton-particle states coupled to even-even Pt cores, and the 11/2 excitations represent lh,l,2 proton-hole states coupled to even-even Hg cores. The data are taken from Nuclear Data Compilations (Harmatz 1978, Brown 1980, Ellis-Akovali 1981, Firestone 1981, Shirley 1981) and references cohtained therein, as well as from other or more recent work (Vieu 1974, Hoglund et a1 1975, Wood er al 1976, Wood and Fink 1976, Gono et , Grimm 1978, Munger and Peterson 1978, Zganjar 1980, Braga and Fink 1981, Zganjar et a1 1981, Bourgeois et al 1982.…”

Section: Odd-a Nuclei: Intruder States and Shape Coexistence In The R...mentioning

confidence: 99%

Advances in studies of nuclei far from stability

1985

View full text Add to dashboard Cite

Studies of the structure and decay modes of nuclei far from stability have yielded many new insights which were not seen in nuclei near the line of p stability. The results of recent experimental and theoretical investigations are presented and the new insights being gained are discussed. Some of the highlights described include groundstate proton radioactivity, &delayed 2n, 3n and 2p decays, the coexistence of states built on quite different nuclear shapes in the same nucleus, new regions of strongly deformed nuclei, and the importance of the reinforcement of proton and neutron shell gaps on the shape of a nucleus.

show abstract

Section: Odd-a Nuclei: Intruder States and Shape Coexistence In The R...mentioning

confidence: 99%

Advances in studies of nuclei far from stability

1985

View full text Add to dashboard Cite

show abstract

“…A more accurate depiction of their work is that neutron emission characteristics cannot be interpreted without considering the effects of high level density. The pandemonium controversy [8] arose partly from the fact that, at the time, there was no capability to compute nuclear properties using a sufficiently complete microscopic model of the nucleus.State-of-the-art models are now capable of computing decay properties of atomic nuclei, such as lifetimes and branching ratios. It has become increasingly clear that the β-decay observables are profoundly influenced by nuclear…”

mentioning

confidence: 99%

Evidence for Gamow-Teller Decay ofNi78Core from Beta-Delayed Neutron Emission Studies

et al. 2016

View full text Add to dashboard Cite

The β-delayed neutron emission of 83;84 Ga isotopes was studied using the neutron time-of-flight technique. The measured neutron energy spectra showed emission from states at excitation energies high above the neutron separation energy and previously not observed in the β decay of midmass nuclei. The large decay strength deduced from the observed intense neutron emission is a signature of Gamow-Teller transformation. This observation was interpreted as evidence for allowed β decay to 78 Ni core-excited states in 83;84 Ge favored by shell effects. We developed shell model calculations in the proton fpg 9=2 and neutron extended fpg 9=2 þ d 5=2 valence space using realistic interactions that were used to understand measured β-decay lifetimes. We conclude that enhanced, concentrated β-decay strength for neutron-unbound states may be common for very neutron-rich nuclei. This leads to intense β-delayed high-energy neutron and strong multineutron emission probabilities that in turn affect astrophysical nucleosynthesis models. DOI: 10.1103/PhysRevLett.117.092502 β-delayed neutron emission from fission fragments was first observed in 1939 following the neutron bombardment of uranium salts [1]. It was recognized that the delayed neutron energies and emission probabilities, P n , are important parameters to model environments that involve neutron-rich isotopes. Two of the main applications are in nuclear reactor physics [2] and r-process nucleosynthesis [3]. Because β-delayed neutron precursors are neutron rich and far from stability, they are always relatively difficult to produce and study. Advances in detector capabilities allowed for pioneering measurements of neutron emission spectra of fission fragments [4,5]. In these experiments, resonancelike behavior was observed in the neutron emission spectrum [4,6].These efforts were halted in the following decade by several factors. First, it became increasingly difficult to produce species with larger neutron excess. Second, the very influential work by Hardy, Johnson, and Hansen on "pandemonium" attributed the features of the neutron spectra to purely statistical effects and warned against overinterpretation of the measurements [7]. Misinterpretations of their work attributed decay observables of all heavy nuclei to gross features of the decay strength and statistical fluctuations of the level density. A more accurate depiction of their work is that neutron emission characteristics cannot be interpreted without considering the effects of high level density. The pandemonium controversy [8] arose partly from the fact that, at the time, there was no capability to compute nuclear properties using a sufficiently complete microscopic model of the nucleus.State-of-the-art models are now capable of computing decay properties of atomic nuclei, such as lifetimes and branching ratios. It has become increasingly clear that the β-decay observables are profoundly influenced by nuclearPublished by the American Physical Society under the terms of the Creative Commons Attribution 3.0 Lic...

show abstract

“…Several reasonably practical developments are on the horizon: heavy ion induced satellite X-ray emission (HISXE) for chemical information about elements (81,82), positron scattering and positronium chemistry (83), muonium chemistry (84,85), and 7-ray (from t98Au) diffractometry (86). Continuing the pandemonium decay scheme story the 3 decay of ,45Gd has been compared to it and the result casts doubt on decay schemes determined solely by statistical techniques (87), The puzzling lack of neutrinos from solar experiments involving 37C1 has resulted in alternative proposals and theories: measurement of ^Tc and produced by 14-MeV neutrinos from 8B decay (88) for example. Scientists in the USSR estimated the rest mass of the neutrino to be 14 eV or less, and the possibility of neutrino oscillators was proposed, but now a team at Cal Tech has found evidence to support a massless neutrino (89).…”

Section: Health Physics the Literature And Physicsmentioning

confidence: 99%