The isovector quadrupole-quadrupole interaction used in shell model calculations

Fayache, M. S.; Sharma, S. Shelly; Zamick, Larry

doi:10.1016/0370-2693(95)00899-v

Cited by 10 publications

(14 citation statements)

References 20 publications

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“…Br &3.6. This point has been recently studied by Fayache, Sharma and Zamick [38]. From an experimental point of view, it would be helpful to have more data on 10 Be.…”

Section: Conclusion and Suggested Experimentsmentioning

confidence: 93%

Scissors Modes and Spin Excitations in Light Nuclei IncludingΔN=2 Excitations: Behaviour of8Be and10Be

1996

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Shell model calculations are performed for magnetic dipole excitations in 8 Be and 10 Be, first with a quadrupole quadrupole interaction (Q } Q) and then with a realistic interaction. The calculations are performed both in a 0p space and in a large space which includes all 2 | excitations. In the 0p with Q } Q we have an analytic expression for the energies of all states. In this limit we find that in 10 Be the L=1 S=0 scissors mode with isospin T=1 is degenerate with that of T=2. By projection from an intrinsic state we can obtain simple expressions for B(M1) to the scissors modes in 8 Be and 10 Be. We plot cumulative sums for energy-weighted isovector orbital transitions from J=0 + ground states to the 1 + excited states. These have the structure of a low-energy plateau and a steep rise to a high-energy plateau. The relative magnitudes of these plateaux are discussed. By comparing 8 Be and 10 Be we find that contrary to the behaviour in heavy deformed nuclei, B(M1) orbital is not proportional to B(E2). On the other hand, a sum rule which relates B(M1) to the difference (B(E2) isoscalar &B(E2) isovector ) succeeds in describing the difference in behaviours in the two nuclei. The results for Q } Q and the realistic interactions are compared, as are the results in the 0p space and the large (0p+2 |) space. The Wigner supermultiplet scheme is a very useful guide in analyzing the shell model results.

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“…Br &3.6. This point has been recently studied by Fayache, Sharma and Zamick [38]. From an experimental point of view, it would be helpful to have more data on 10 Be.…”

Section: Conclusion and Suggested Experimentsmentioning

confidence: 93%

Scissors Modes and Spin Excitations in Light Nuclei IncludingΔN=2 Excitations: Behaviour of8Be and10Be

1996

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“…In a previous work [1], for a shell model calculation of 10 Be, a quadrupole-quadrupole interaction, of the form −χQ · Q[1 + Bτ (1) · τ (2)], was used which has a combination of the usual isospin-independent first term and the less common isospin-dependent second term. In that reference motivations were provided for the selection of both the specific interaction and the specific nucleus that were studied.…”

Section: Introductionmentioning

confidence: 99%

“…In the previous calculation of 10 Be in the 0p shell [1], the answer was a resounding no! In the 0p space calculation with B = 0, the ground state has J = 0 + and orbital symmetry [42].…”

Section: Introductionmentioning

confidence: 99%

“…There is a two-fold degeneracy for the first excited state: two J = 2 + states both with orbital symmetry [42], corresponding to K = 0 and K = 2. The focus of interest in [1] was also on two higher-lying degenerate L = 1 S = 1 states: one with orbital symmetry [33], and the other [411]; in each of these two cases from the L = 1 S = 1 configuration one obtains a triplet of states J = 0, 1, 2.…”

Section: Introductionmentioning

confidence: 99%

“…In this paper, in the hope of preventing the aforementioned undesirable collapse, we extend the calculations of [1] in two ways. First, we increase the model space to include not only all the possible configurations in the 0p shell, but also all 2 ω (i.e.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

The isospin-dependent quadrupole-quadrupole interaction used in shell model calculations – the effects of including ΔN = 2 excitations and a two-body spin-orbit interaction term

Fayache

Sharon

Zamick

et al. 2000

EPJ A

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The effect of the "B" term in the interaction −χQ(1) · Q(2)[1 + Bτ (1) · τ (2)] was previously considered in the 0p shell (small space). It is now studied in a larger space which additionally includes ∆N = 2 excitations. When B is made sufficiently negative we still obtain for 10 Be, even in the larger space, an unphysical collapse of some of the low-lying states so that their energies are less than the energy of the conventional J = 0 + ground state. This effect, however, occurs for values of B considerably more negative than was the case in the smaller space. It is shown that the inclusion of an additional two-body spin-orbit interaction term prevents this unrealistic collapse in both the large and small spaces.

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Effect of two RPA phonons on the spectrum of the low-lying magnetic dipole transitions in deformed nuclei

et al. 1996

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The isovector quadrupole-quadrupole interaction used in shell model calculations

Cited by 10 publications

References 20 publications

Scissors Modes and Spin Excitations in Light Nuclei IncludingΔN=2 Excitations: Behaviour of8Be and10Be

Scissors Modes and Spin Excitations in Light Nuclei IncludingΔN=2 Excitations: Behaviour of8Be and10Be

The isospin-dependent quadrupole-quadrupole interaction used in shell model calculations – the effects of including ΔN = 2 excitations and a two-body spin-orbit interaction term

Effect of two RPA phonons on the spectrum of the low-lying magnetic dipole transitions in deformed nuclei

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