Spin-isospin strength and spectral functions

Rijsdijk, G.A.; Geurts, W.J.W.; Brand, M.G.E.; Allaart, K.; Dickhoff, W. H.

doi:10.1103/physrevc.48.1752

Cited by 19 publications

(17 citation statements)

References 57 publications

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“…This result is due to the fact that in these RPA methods only particle-hole and hole-particle excitation amplitudes are considered. The bulk of the Gamow-Teller (n, p) strength in magic nuclei comes &om amplitudes with shell model orbits for the proton and neutron on the same side of the Fermi level [2]. In accordance with Refs.…”

supporting

confidence: 86%

“…1. If the self-energy Z' is expanded to second or higher order in the (G-matrix) interaction V, one finds the aforementioned smearing of the Fermi surface which finds expression in nonzero particle addition as well as removal amplitudes for a given orbit a in the single-particle propagator [ One finds [1,2] that for a suitably chosen set of shell model orbits o, this propagator is to a very good approximation diagonal in that model space: (2) If one assumes that particles and holes propagate in full interaction with the nuclear medium but without any direct or indirect interaction with each other (dressed independent particle approximation (DIPA) in Ref. [2]) the polarization propagator [2, 9 - …”

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confidence: 99%

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Gamow-Teller (p,n) and (n,p) strength in a dressed extended random phase approximation

1994

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Induced forces of second order in the nucleon-nucleon G-matrix interaction are included in a random phase approximation (RPA) type formalism with dressed single-particle propagators. The predictions of a considerable amount of Gamow-Teller (n, p) strength for magic nuclei with neutron excess, found in earlier dressed RPA calculations, are not modi6ed by the induced forces. Also the distribution of (p, n) strength is only a little affected by the induced interactions. It is therefore concluded that the relatively simple dressed RPA method is a suitable one to calculate excitation strengths.PACS number(s): 25.40.Kv, 21.60.Jz, 24.10.Cn

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confidence: 86%

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confidence: 99%

Gamow-Teller (p,n) and (n,p) strength in a dressed extended random phase approximation

1994

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“…They analyzed the reactions 90 Zr(p,n) and 90 Zr(n,p) to obtain the sum of Gamow-Teller strengths S β − and S β + , respectively, up to 50 MeV excitation energy. Their experimental results are shown in Figure 9, in comparison to calculations by Dang et al [19] and Rijsdijk et al [20]. After subtraction of the isovector spin monopole (IVSM) strength, the experimental results of Sakai and collaborators are S β − = 28.6 and S β + = 2.8.…”

Section: Gamow-teller Transitionsmentioning

confidence: 76%

“…One of the important successes of the nuclear shell model, which was established in 1949 by Mayer and Jensen, was the explanation of the magic numbers (Z or N = 2, 8,20,28,50,82). This could be achieved by adding a strong spin-orbit force to the nuclear mean field.…”

Section: Arima-horie Effect and Configuration Mixingmentioning

confidence: 99%

A short history of nuclear magnetic moments and GT transitions

Arima

2011

Sci. China Phys. Mech. Astron.

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We summarize the history and our present understanding of nuclear magnetic moments and Gamow-Teller transitions. The roles of configuration mixing, meson exchange currents and relativistic effects are examined. Experimental evidence for the importance of tensor correlations is also discussed. nuclear magnetic moments, Gamow-Teller transitionsOne of the important successes of the nuclear shell model, which was established in 1949 by Mayer and Jensen, was the explanation of the magic numbers (Z or N = 2, 8, 20, 28, 50, 82). This could be achieved by adding a strong spin-orbit force to the nuclear mean field. In this extreme single-particle picture, the magnetic moment of an odd-A nucleus is carried only by one valence nucleon, which leads to the well known Schmidt values:where μ N = e/2M is the nuclear magneton, j = ± 1 2 the spin of a single particle state, and g = 1(0), g s = 5.59(−3.83) are the orbital and spin g-factors of the odd proton (neutron). If one plots eq. (1) as a function of j, one obtains two lines, which are called the Schmidt lines. It was observed in the early 1950s [1], however, that almost all nuclear magnetic moments are sandwiched between the two Schmidt lines, and that some of them, like 17 F or 15 N, show only small deviations from the Schmidt values, while others, like 209 Bi or 207 Tl, show very large deviations. In the extreme single-particle picture, one expects that the valence proton (or proton hole) in the latter nuclei moves independent about the center of 208 Pb, similar to the former nuclei which have 16 O as a core.In 1954, Arima and Horie [2] pointed out a very distinct difference between these two groups of nuclei: The cores of the nuclei in the first group ( 16 O and 40 Ca cores) are LSclosed, i.e., the spin-orbit partners j = ± 1 2 of the core are completely occupied. Therefore they are expected not to be excited strongly by the M1 external field. On the other hand, the cores of the nuclei in the second group (like 208 Pb) are j jclosed, i.e., one of the spin-orbit partners is open, and an M1 external field can strongly excite core nucleons to the empty spin-orbit partner. This M1 giant resonance state of the core can be momentary excited by the interaction with the valence nucleon. This is the idea of the first order configuration mixing, which is also called the first order core polarization. We show it graphically in Figure 1.The magnetic moment of 209 Bi including the correction from first order configuration mixing can be expressed as [2,3] ψ 209 Bi |μ|ψ 209 Bi = 0 + × h 9/2 ,where 0 + denotes the ground state of the 208 Pb core, and 1 + the M1 giant resonance state which is made of two states, namely a proton (or neutron) particle-hole pair h 9/2 h −1 11/2 (or i 11/2 i −1 13/2 ) on top of the 0 + state. In this configuration mixing process, all protons in the h 11/2 orbit and all neutrons in the i 13/2 orbit participate collectively in the magnetic dipole excitation. Therefore their matrix elements are large and contribute very much to modify the magnetic moment of 209...

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“…This spreading of the single-particle strength leads to a quenching of particle-hole excitations of all angular momenta and in all reactions. The specific treatment of GT and spin-dipole excitations has been discussed in detail for targets of 48 Ca and 90 Zr [ 132,133]. For instance, because of excitations in the target ground state, it was calculated that the total GT strength in 48 Ca (p,n) is 30 units, 6 units greater than the sum rule limit 3 (N-Z ).…”

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confidence: 99%