Downloaded from the self-conjugate 4n nuclei which we call a-nuclei are especially stable energetically, therefore the fragmentation (or fission) thresholds of respective nuclei into constituent a-nuclei plus a residual nucleus lie in series starting in the region of quite low excitation energy.Since a-nuclei are strongly bound systems, they are hardly excited even when two a-nuclei are in a close distance. The fact that inter-nucleus forces between spin-isospin saturated nuclei are generally weak promotes further the tendency that a-nuclei preserve their identity in their interaction process. Furthermore the repulsive force of a short range part of the inter-nucleus inter-at Purdue University Libraries ADMN on June 1, 2015 http://ptps.oxfordjournals.org/ Downloaded from factorily the low-lying positive-parity excited states, 02 + at 7.66 MeV and 22 + (or 08 + ?) at ,...__,10.3 MeV shown in Fig. 1-1.From these studies, the ground rotational band (consisting of ground 01 +, 2 1 + at 4.44 MeV and 41 + at 14.08 MeV) was regarded as having a strong shellmodel-like character, although a-clustering effect is important. The latter nature (namely the persistency of a-clustering) was investigated in detail by Abe, Hiura and Tanaka 17 l by the use of the molecular orbital method preserving the spatial symmetry of [ 4 8 ]. Takigawa and Arima 18 l investigated the *> Many works were made with various frameworks and a-a potentials. Here, however, we do not mention them in detail. See a review article given by Tamagaki and Fujiwara for the works on the 3a problem.••> at Purdue University Libraries ADMN on June 1, 2015 http://ptps.oxfordjournals.org/ Downloaded from 15 0, 15 N, 17 0 and 11 F, the spacing between the centroids of the p and the sd shells is estimated as about 17 MeV. ii) We can deduce a value of fiw = 13.4 MeV corresponding to the harmonic oscillator parameter b = 1.76 fm at Purdue University Libraries ADMN on June 1, 2015 http://ptps.oxfordjournals.org/ Downloaded from Another standpoint for incorporating a 4p-4h configuration was the weak coupling model by Arima, Horiuchi and Sebe 58 >• 59 >• 60 > which assumed that the at Purdue University Libraries ADMN on June 1, 2015 http://ptps.oxfordjournals.org/ Downloaded from at Purdue University Libraries ADMN on June 1, 2015 http://ptps.oxfordjournals.org/ Downloaded from *' The RGM study for the "O+a system was also carried out by Siinkel and Wildermuth."'l **l Similar RGM analysis of the "0-a interaction was made by Ando, Ikeda and Suzuki 106 J by comparing with the a-a and "0-16 0 cases. at Purdue University Libraries ADMN on June 1, 2015 http://ptps.oxfordjournals.org/ Downloaded from at Purdue University Libraries ADMN on June 1, 2015 http://ptps.oxfordjournals.org/ Downloaded from *> As for wi'lr(t), harmonic oscillator functions and locally peaked Gaussian functions are also available by the use of fPNLM(J., v, S). Actually, the latter functions were examined and were found to give the same results obtained by the set (2·5) (Ref. 41)). at Purdue University Lib...
