TY - JOUR

T1 - Nuclear level density, thermalization, chaos, and collectivity

AU - Zelevinsky, Vladimir

AU - Horoi, Mihai

N1 - Funding Information:
Many results mentioned above were derived in collaboration with R.A. Sen’kov and S. Karampagia. Special gratitude goes to the students who took part at different stages of this work, J. Kaiser, M. Ghita, J. Dissanayake, A. Renzaglia, and A. Berlaga. Friendly discussions with B.A. Brown, A. Volya, N. Auerbach, Y. Alhassid, S. Gorieli, S. Grimes, A. Voinov, and the Oslo group were always useful and helpful. For many years the work on level densities was supported by the US National Science Foundation grants PHY-9513893 , PHY-9901241 , PHY-0070911 , PHY-0244453 , PHY-0555366 , PHY-0758099 , PHY-1068217 , and PHY-1404442 . V.Z. acknowledges the grant from the Binational Science Foundation US–Israel and a useful discussion at the seminar of the Tel Aviv University. M.H. also acknowledges the US Department of Energy grants DE-FC02-09ER41584 and DE-SC0008529 .
Funding Information:
Many results mentioned above were derived in collaboration with R.A. Sen'kov and S. Karampagia. Special gratitude goes to the students who took part at different stages of this work, J. Kaiser, M. Ghita, J. Dissanayake, A. Renzaglia, and A. Berlaga. Friendly discussions with B.A. Brown, A. Volya, N. Auerbach, Y. Alhassid, S. Gorieli, S. Grimes, A. Voinov, and the Oslo group were always useful and helpful. For many years the work on level densities was supported by the US National Science Foundation grants PHY-9513893, PHY-9901241, PHY-0070911, PHY-0244453, PHY-0555366, PHY-0758099, PHY-1068217, and PHY-1404442. V.Z. acknowledges the grant from the Binational Science Foundation US?Israel and a useful discussion at the seminar of the Tel Aviv University. M.H. also acknowledges the US Department of Energy grants DE-FC02-09ER41584 and DE-SC0008529.
Publisher Copyright:
© 2018 Elsevier B.V.

PY - 2019/3

Y1 - 2019/3

N2 - The knowledge of the level density is necessary for understanding nuclear reactions involving excited nuclear states. In particular, it is an important element in description of astrophysical processes and in technological applications. This review article explains main ideas of physics forming the level density in complex nuclei that grows very fast due to combinatorial complexity of total excitation energy shared by many constituents. This can be translated into a language of statistical physics by the Darwin–Fowler method. We briefly go through the historical development from the nuclear Fermi-gas model to the self-consistent mean field including the pairing effects. At the next step we introduce the ideas of thermalization in a closed mesoscopic system and quantum chaos with very complicated eigenfunctions. This is supported by the experience of the shell model in a limited orbital space that either provides an exact solution or uses the Monte Carlo approach. The statistical method of moments allows one to avoid the exact diagonalization keeping intact the quality of the results. We discuss the popular “constant temperature model” that describes well available data and the shell-model results; it is shown that its success cannot be explained by the phase transition from superfluid to a normal phase. The interpretation is suggested, supported by the numerical studies, in terms of dynamical chaotization including the collective enhancement of the level density. The role of incoherent collision-like interactions is stressed as a necessary element of the thermalization process.

AB - The knowledge of the level density is necessary for understanding nuclear reactions involving excited nuclear states. In particular, it is an important element in description of astrophysical processes and in technological applications. This review article explains main ideas of physics forming the level density in complex nuclei that grows very fast due to combinatorial complexity of total excitation energy shared by many constituents. This can be translated into a language of statistical physics by the Darwin–Fowler method. We briefly go through the historical development from the nuclear Fermi-gas model to the self-consistent mean field including the pairing effects. At the next step we introduce the ideas of thermalization in a closed mesoscopic system and quantum chaos with very complicated eigenfunctions. This is supported by the experience of the shell model in a limited orbital space that either provides an exact solution or uses the Monte Carlo approach. The statistical method of moments allows one to avoid the exact diagonalization keeping intact the quality of the results. We discuss the popular “constant temperature model” that describes well available data and the shell-model results; it is shown that its success cannot be explained by the phase transition from superfluid to a normal phase. The interpretation is suggested, supported by the numerical studies, in terms of dynamical chaotization including the collective enhancement of the level density. The role of incoherent collision-like interactions is stressed as a necessary element of the thermalization process.

KW - Chaos

KW - Nuclear level density

KW - Nuclear reactions

KW - Nuclear structure

UR - http://www.scopus.com/inward/record.url?scp=85059035571&partnerID=8YFLogxK

U2 - 10.1016/j.ppnp.2018.12.001

DO - 10.1016/j.ppnp.2018.12.001

M3 - Review article

AN - SCOPUS:85059035571

VL - 105

SP - 180

EP - 213

JO - Progress in Particle and Nuclear Physics

JF - Progress in Particle and Nuclear Physics

SN - 0146-6410

ER -