dorsal/arxiv
View SchemaOn the nature of nuclear dissipation, as a hallmark for collective dynamics at finite excitation
| Authors | Helmut Hofmann, Fedor A. Ivanyuk, Shuhei Yamaji |
|---|---|
| Categories | |
| ArXiv ID | nucl-th/9510055 |
| URL | https://arxiv.org/abs/nucl-th/9510055 |
| DOI | 10.1016/0375-9474(95)00442-4 |
| Journal | Nucl.Phys. A598 (1996) 187-234 |
Abstract
We study slow collective motion of isoscalar type at finite excitation. The collective variable is parameterized as a shape degree of freedom and the mean field is approximated by a deformed shell model potential. We concentrate on situations of slow motion, as guaranteed, for instance, by the presence of a strong friction force, which allows us to apply linear response theory. The prediction for nuclear dissipation of some models of internal motion are contrasted. They encompass such opposing cases as that of pure independent particle motion and the one of "collisional dominance". For the former the wall formula appears as the macroscopic limit, which is here simulated through Strutinsky smoothing procedures. It is argued that this limit hardly applies to the actual nuclear situation. The reason is found in large collisional damping present for nucleonic dynamics at finite temperature $T$. The level structure of the mean field as well as the $T$-dependence of collisional damping determine the $T$-dependence of friction. Two contributions are isolated, one coming from real transitions, the other being associated to what for infinite matter is called the "heat pole". The importance of the latter depends strongly on the level spectrum of internal motion, and thus is very different for "adiabatic" and "diabatic" situations, both belonging to different degrees of "ergodicity".
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"abstract": "We study slow collective motion of isoscalar type at finite excitation. The\ncollective variable is parameterized as a shape degree of freedom and the mean\nfield is approximated by a deformed shell model potential. We concentrate on\nsituations of slow motion, as guaranteed, for instance, by the presence of a\nstrong friction force, which allows us to apply linear response theory. The\nprediction for nuclear dissipation of some models of internal motion are\ncontrasted. They encompass such opposing cases as that of pure independent\nparticle motion and the one of \"collisional dominance\". For the former the wall\nformula appears as the macroscopic limit, which is here simulated through\nStrutinsky smoothing procedures. It is argued that this limit hardly applies to\nthe actual nuclear situation. The reason is found in large collisional damping\npresent for nucleonic dynamics at finite temperature $T$. The level structure\nof the mean field as well as the $T$-dependence of collisional damping\ndetermine the $T$-dependence of friction. Two contributions are isolated, one\ncoming from real transitions, the other being associated to what for infinite\nmatter is called the \"heat pole\". The importance of the latter depends strongly\non the level spectrum of internal motion, and thus is very different for\n\"adiabatic\" and \"diabatic\" situations, both belonging to different degrees of\n\"ergodicity\".",
"arxiv_id": "nucl-th/9510055",
"authors": [
"Helmut Hofmann",
"Fedor A. Ivanyuk",
"Shuhei Yamaji"
],
"categories": [
"nucl-th"
],
"doi": "10.1016/0375-9474(95)00442-4",
"journal_ref": "Nucl.Phys. A598 (1996) 187-234",
"title": "On the nature of nuclear dissipation, as a hallmark for collective dynamics at finite excitation",
"url": "https://arxiv.org/abs/nucl-th/9510055"
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