Elastic scattering of α-particles by 12C and the structure of 16O

111Electric transition probabilities and a-widths of 16 0 predicted by a 12 C+a cluster-coupling model are compared with experiment. Almost all the data are reasonably well reproduced. It is shown that the first excited o+ state of "0 is successfully understood by the present model. § l. IntroductionIn a previous paperll (referred to as I) we showed that low-lying T=O levels of 16 0 are satisfactorily well reproduced by 12 C +a cluster-coupling model.In this paper we further try to confirm validity of our model. In § 2 the mysterious zero plus state is discussed from the viewpoint of a-clustering. Electric transition probabilities and a-widths are calculated by using the wave functions obtained in I and compared with available experimental data in § § 3 and 4, respectively. § 2. The mysterious zero plus state and a-clustering Figure 1 displays how eigenvalues Er and expectation values of T, VnJ andL1Ec for the three lowest o+ states depend on the maximum number of N adopted in solving Eq. (I· 35). The 01 + state has a weak N-dependence: This is because the closed shell (Op-Oh) state is so stable that it hardly couples collectively with excited configurations (confs) and in consequence its component in the 01 + state is higher than about 90%. In this sense the ground state is strongly governed by a shell effect.On the other hand, the states 02 + and 03 + show a striking contrast to the 01 + state, especially their kinetic and nuclear potential energies decreasing drastically as N iacreases. As can be clearly seen from the L1E0-curve, when N increases from 8 to 10, the 03 + state shows a sudden change which may be called a "phase transition". This anomaly indicates a rearrangement of main confs in the 03 + state. When N = 6, the wave functions of the states 02 + and 03 + are mainly given as linear combinations of the confs of the ( 4, 2) and (2, 0) representations (reps). Three states of the (8, 4), (6, 2) and ( 4, 0) reps appear when N = 8,

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“…The very condition has enabled us to reproduce the shell-like states which were not dealt with in Ref. 26). …”

Section: Discussionmentioning

confidence: 95%

Structure Study of T = 0 States in 16O by 12C + Cluster-Coupling Model. II

Suzuki¹

1976

Progress of Theoretical Physics

129

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“…The value of the potential strength V 0 was changed so as to obtain a reasonable fit as follows: For positive parity states it was -2.31 MeV for The POT calculation does not explicitly take the Pauli principle into account. The calculation by Terasawa et al 186 l is a successful example on this standpoint. They had to introduce many phenomenological parameters in the optical potential.…”

Section: (3·29)mentioning

confidence: 99%

Chapter II. Comprehensive Study of Alpha-Nuclei

Fujiwara

Horiuchi

Ikeda

et al. 1980

Prog. Theor. Phys. Suppl.

378

393

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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...

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Non-Rutherford 4He cross sections for ion beam analysis

Leavitt

McIntyre

1991

Nuclear Instruments and Methods in Physics Research Section B:

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Elastic scattering of α-particles by 12C and the structure of 16O

Cited by 11 publications

References 37 publications

Structure Study of T = 0 States in 16O by 12C + Cluster-Coupling Model. II

Structure Study of T = 0 States in 16O by 12C + Cluster-Coupling Model. II

Chapter II. Comprehensive Study of Alpha-Nuclei

Non-Rutherford 4He cross sections for ion beam analysis

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