Study of the neutron-rich nuclei with N=21, 35Si and 33Mg, by beta decay of 35Al and 33Na
✍ Scribed by S. Nummela; P. Baumann; E. Caurier; S. Courtin; P. Dessagne; E. Holmlund; A. Jokinen; A. Knipper; G. Le Scornet; C. Mieh; F. Nowacki; L.G. Lyapin; M. Oinonen; E. Poirier; Z. Radivojevic; M. Ramdhane; W.H. Trzaska; G. Walter; J. Äystö
- Publisher
- Elsevier Science
- Year
- 2002
- Tongue
- English
- Weight
- 101 KB
- Volume
- 701
- Category
- Article
- ISSN
- 0375-9474
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✦ Synopsis
The first information on the level structure of the N = 21 nuclei, 35 Si and 33 Mg, has been obtained by the beta decay study of 35 Al and 33 Na, produced by fragmentation of an UC target with 1.4 GeV protons at CERN/ISOLDE. The experimental technique involved β-γ, β-γ-γ, and β-n-γ coincidences, neutron spectra being obtained by time of flight measurements. Gamma detection was made either using large Ge counters or small BaF 2 scintillators (for lifetime measurements). In the case of the 35 Al decay, (T 1/2 = 41.6(2.2) ms), a simple structure has been found for the level scheme of 35 Si (Z = 14, N = 21) which has been interpreted with the level sequence : 7/2 -, 3/2 -and 3/2 + corresponding respectively to the ground state and the states at 910 and 974 keV. The life-time of the 974 keV [T 1/2 = 5.9(6) ns] is found consistent with the proposed level scheme and multipolarities. The investigation of the N = 21, very neutron rich isotones, has been carried on with the study of 33 Mg resulting from the 33 Na decay, (T 1/2 = 8.0(6) ms). In this case also, a level scheme could be obtained for the first time, with 5 bound states in 32 Mg and 31 Mg levels, populated in the 1n and 2n channels. These results are compared with sd-fp shell model calculations which give a fair account * Corresponding author.