Lifetime of the 3.19-MeV () State in
- 20 May 1969
- journal article
- research article
- Published by American Physical Society (APS) in Physical Review B
- Vol. 181 (4), 1552-1555
- https://doi.org/10.1103/physrev.181.1552
Abstract
The lifetime of the () 3.19-MeV state in has been measured by obtaining the time distribution of coincidences between positrons forming the state, from the decay of the () 615-keV state in , and 440-keV-decay rays. The metastable (61-sec) state in was generated by the reaction using a 6.10-MeV beam from the University of Iowa Van de Graaff. A 60-sec beam-on-beam-off cycle was employed. Positrons were detected by a 2-in.-diam × 1-in.-high plastic scintillator, and rays by a 1-in. × 1-in. NaI(Tl) scintillator. Both scintillators were viewed by RCA-8575 photomultipliers whose dynodes were gated to avoid damage during the beam-on time. The value obtained for the mean lifetime was (7.72±0.26) × sec which corresponds to a . This value may be compared with the () 1.52-MeV to () ground-state decay, assuming both represent transitions between states. The result indicates that collective admixtures in the and wave functions are larger than for the and levels. This can be understood quantitatively if one considers the low-lying levels in to be shell-model states mixed with rotational states arising from 4p-2h excitation according to a recent model by Gerace and Green.
Keywords
This publication has 6 references indexed in Scilit:
- Deformed states in 42CaNuclear Physics A, 1968
- Energy levels of Z = 11−21 nuclei (IV)Nuclear Physics A, 1967
- The effect of deformed states in the Ca isotopesNuclear Physics A, 1967
- Deformations in the calcium regionNuclear Physics, 1966
- Nuclear energy levels of calcium isotopesPhysics Letters, 1966
- Lifetime of the 1.52-MeV Level inPhysical Review B, 1966