Sum rules in the proton-neutron interacting boson model: Generalized treatment and specific applications

Heyde, K.; Coster, C. De; Ooms, D.

doi:10.1103/physrevc.49.156

Cited by 14 publications

(5 citation statements)

References 46 publications

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“…Primarily, the IBM-2 yielded the nonenergyweighted sum. Recently, energy weighted sums have been derived in the IBM which relate the M1 to the E2 strength (Heyde et al 1994). For easy comparison we have in table 4 given the B(M1) value of equation (5.2) multiplied by 3 MeV which, with suitable choice of parameters, is the energy deduced from the model (Scholten et al 1985, Balantekin and Barrett 1985, Bijker 1985, Walet et al 1985.…”

Section: Comparison Of Different Modelsmentioning

confidence: 99%

Theoretical aspects of the new collective modes in nuclei

Zawischa

1998

J. Phys. G: Nucl. Part. Phys.

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The interpretation of the low-energy orbital magnetic-dipole excitations of nonspherical nuclei, commonly called scissors modes, is examined. Different models are reviewed, and with the help of the fluid dynamical model and microscopic results from different groups, the relations between the models and their limitations are discussed. Contradictions between semiclassical models, algebraic models and microscopic calculations are shown to be only apparent. The emerging picture is that of a semiclassical vorticity mode which can only exist due to quantum effects but nevertheless, in the quantum limit, is spread over a number of states, each of them at most slightly collective. The mode is an example for the vorticity of nuclear currents which in this case has a direct measurable effect, namely the M1 strength itself. The importance of electric-quadrupole strengths to assess the nature of the modes is emphasized.

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Section: Comparison Of Different Modelsmentioning

confidence: 99%

Theoretical aspects of the new collective modes in nuclei

Zawischa

1998

J. Phys. G: Nucl. Part. Phys.

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“…The behaviors of Q 2 and Q 2 v imply that Q p · Q n = ( Q 2 − Q 2 v )/4 increases near the phase transition (Q p,n are the proton and neutron quadrupole moments). Noting the relation between Q p ·Q n and the orbital part of the M1 strength [16], we interpret the partial unquenching of the B(M1) near T = 1.1 MeV as related to the orbital part, while the spin part, dominated by the same operator as the GT strength, remains significantly quenched to higher temperatures.…”

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confidence: 99%

Thermal Properties ofF54e

et al. 1995

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We study the thermal properties of 54 Fe with the Brown-Richter interaction in the complete 1p0f model space. Monte Carlo calculations show a peak in the heat capacity and rapid increases in both the moment of inertia and M 1 strength near a temperature of 1.1 MeV that are associated with the vanishing of proton-proton and neutron-neutron monopole pair correlations; neutron-proton correlations persist to higher temperatures. Our results are consistent with a Fermi gas level density whose back-shift vanishes with increasing temperature.PACS numbers: 21.60. Cs, 21.60.Ka, 27.40.+z, 21.10.Ma Typeset using REVT E X 1 The nuclear level density increases rapidly at excitation energies above several MeV and it becomes difficult to resolve or calculate individual states. In this regime, it is more appropriate to employ a statistical description where observables are averaged over the many levels at a given energy. The concept of an equilibrated compound nucleus is among the most fundamental of nuclear reaction theories [1], and plays a central role in our understanding of processes induced by probes ranging from photons to heavy ions.While the proper description of a compound nucleus is in terms of a microcanonical (fixed-energy) ensemble, it is often more convenient to consider a canonical ensemble whose temperature is chosen to reproduce the average excitation energy. In the past decade, there has been renewed experimental [2] and theoretical [3] effort to explore the properties of heavy nuclei at finite temperature and high spin. The properties of hot nuclei are also important in various astrophysical scenarios, particularly in the late stage of a supernova collapse and explosion [4].Most theoretical approaches to hot nuclei devolve to a mean-field description based on an average configuration [5]. The realization that thermal and quantal fluctuations about the average can be important has prompted more sophisticated approximations [6], although even these have clear limitations. In principle, the nuclear shell model (which provides a complete spectrum and wavefunctions) offers a fully microscopic approach to the problem.However, conventional finite-temperature shell model calculations within a complete major shell are limited to light nuclei ( 20 Ne and 24 Mg) in the sd shell [7].In this Letter, we exploit recently developed Monte Carlo techniques to calculate the thermal properties of 54 Fe in a complete 0hω model space with a realistic interaction. The methods we use describe the nucleus by a canonical ensemble at temperature T = β −1 and employ a Hubbard-Stratonovich linearization of the imaginary-time many-body propagator, e −βH , to express observables as path integrals of one-body propagators in fluctuating auxiliary fields [8]. Since Monte Carlo techniques avoid an explicit enumeration of the manybody states, they can be used in model spaces far larger than those accessible to conventional methods. The Monte Carlo results are in principle exact and are in practice subject only to 2 controllable samp...

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“…One can prove that the const. 1 = \/5-As one knows, the total pseudo-spin momentum /" = VEpi in the SO (8) case (This can be proven by secondly quantized formalism of the k-i basis (SO(8) case)). Therefore one may have J = 1= -5(6ji6tOoi in t h e S0 ( 8 ) case.…”

Section: Discussionmentioning

confidence: 88%

“…By these formulae, one can obtain the sum rules in the sd IBM-2. References [4]- [8] were actually presented within the framework of the sd IBM-2 along this line. The EW and NEW sum rule in the sdg IBM-2 is similar to that in the sd IBM-2 except that it is much more complex in mathematics.…”

Section: ((A B)c) = (A B)c -E Ab C C(a B) ((Abyc){ = £Cf 7 {(I B)\c ...mentioning

confidence: 99%

“…(i.e., L g = y/ffi (gg)W). By some approximations or conventions, such as eliminating some terms, they can be simplified as those similar to Heyde, Ginocchio and Barrett's procedures, and the results are consistent with the previous studies.I [4][5][6][7][8][9] ' 14 ! Before going on, I would like to point out some errors and misprints in Heyde and his collaborators papers.…”

Section: + S^w(dg)mentioning

confidence: 99%

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