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Start Over Descriptor "hot nuclei" Topic nuclear physics
11 results on '"hot nuclei"'

1. The effect of temperature and pairing on nuclear pseudospin symmetry.

Author

Malheiro, M., Lisboa, R., Carlson, B. V., and Alberto, P.

Subjects
*NEUTRONS, *NUCLEAR reactions, *COLLISIONS (Nuclear physics), *PARTICLES (Nuclear physics), *POLARIZATION (Nuclear physics), *NUCLEAR physics
Abstract

We study the effects of temperature andpairing on pseudospin symmetry in spherical and deformed nucleus using the Dirac—Hartree—Bogoliubov (DHB) formalism. We include temperature in the DHB equation using the Matsubara formalism and analyze changes in the neutron single particle levels with the temperature. We show that the effect of temperature on the pseudospin energy splitting is small. We find that this splitting decreases at high temperatures and that pseudospin partners are almost degenerate in deformed hot nuclei, indicating the dependence of pseudospin symmetry on the nuclear surface. Furthermore, for reasonable values of the pairing interaction, we also show that pairing does not affect the pseudospin symmetry in deformed nuclei. Finally, we find that the effect of temperature on pseudospin doublets is more pronounced in spherical nuclei than in deformed ones. [ABSTRACT FROM AUTHOR]

Published
2009
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2. The Gamma Decay of the GDR Under Extreme Conditions.

Author

Wieland, O.

Subjects
*GAMMA decay, *CONTROLLED fusion, *PARTICLES (Nuclear physics), *NUCLEAR reactions, *NUCLEAR physics
Abstract

The study of the γ decay from the giant dipole resonance (GDR) at finite temperature and far from stability allows to obtain information on the properties of nuclei in different regimes. Exclusive measurements of γ -decays with fusion reactions were made at LNL (INFN) in order to address different physical problems. First, the measurement of the temperature dependence of the GDR width up to T = 4 MeV in the mass region A = 130 will be shown together with its interpretation in terms of thermal shape fluctuation calculations. Secondly, a measurement of the isospin mixing for nuclei in the mass region A = 80 at temperature around T = 2 MeV is described. Finally the search for the pygmy dipole resonance in the neutron rich 68Ni nucleus, produced by fragmentation at GSI, will be presented. Coulomb excitation at 600 MeV/nucleon was employed and the γ -rays were detected with the RISING array. [ABSTRACT FROM AUTHOR]

Published
2009
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3. Mapping the demise of collective motion in nuclei at high excitation energy

Author

S. Pirrone, Lucrezia Auditore, R. Coniglione, Domenico Santonocito, Antonio Trifiro, C. Monrozeau, E. Migneco, E. La Guidara, C. Maiolino, R. Alba, G. Bellia, O. Wieland, G. Cardella, Marina Trimarchi, F. Hongmei, H. X. Huang, Michele Papa, C. Agodi, P. Piattelli, Y. Blumenfeld, F. Rizzo, A. Del Zoppo, E. De Filippo, Paolo Sapienza, Institut de Physique Nucléaire d'Orsay (IPNO), Université Paris-Sud - Paris 11 (UP11)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), and Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Paris-Sud - Paris 11 (UP11)

Subjects
Physics, Quenching, Nuclear and High Energy Physics, Range (particle radiation), Hot nuclei, Giant Dipole Resonance, [PHYS.NUCL]Physics [physics]/Nuclear Theory [nucl-th], Fusion reactions, Statistical Model, 010308 nuclear & particles physics, Detector, 01 natural sciences, Resonance (particle physics), lcsh:QC1-999, Nuclear physics, Dipole, 0103 physical sciences, Nuclear fusion, Nuclear Experiment, 010306 general physics, lcsh:Physics, Energy (signal processing), Excitation
Abstract

High energy gamma-rays from the 116Sn + 24Mg reaction at 23A MeV were measured using the MEDEA detector at LNS – INFN Catania. Combining this new data with previous measurements yields a detailed view of the quenching of the Giant Dipole Resonance as a function of excitation energy in nuclei of mass A in the range 120÷132. The transition towards the disappearance of the dipole strength, which occurs around 230 MeV excitation energy, appears to be remarkably sharp. Current phenomenological models give qualitative explanations for the quenching but cannot reproduce its detailed features. Keywords: Giant Dipole Resonance, Hot nuclei, Fusion reactions, Statistical Model

Published
2018
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4. Properties of hot nuclear fragments formed in multifragmentation and their astrophysical implications

Author

Souliotis, G.A., Botvina, A.S., Shetty, D.V., Keksis, A.L., Jandel, M., Veselsky, M., and Yennello, S.J.

Subjects
*ASTROPHYSICS, *NUCLEAR reactions, *NUCLEAR physics, *QUANTUM theory
Abstract

Abstract: The process of nuclear multifragmentation leads to thermodynamic conditions akin to those encountered in the collapse/explosion of massive stars. Thus, the knowledge obtained from studying multifragmentation may be applied to describe matter distribution in supernova. Along these lines, the present study focuses on the symmetry energy of hot fragments produced in the multifragmentation of neutron-rich systems following collisions near the Fermi energy. The experiments consist of high-resolution mass spectrometric measurements of the isotopic and velocity distributions of heavy projectile fragments. The data were systematically compared to calculations with the Statistical Multifragmentation Model (SMM). The study indicates a gradual decrease of the symmetry energy coefficient from the standard value of ∼25MeV in the compound nucleus regime (E ∗/A <2MeV) towards ∼15MeV in the bulk multifragmentation regime (E ∗/A >4MeV). The isotopic distributions of the hot fragments are very wide and extend towards or beyond the neutron drip-line. These findings may have important implications to the composition and evolution of hot astrophysical environments, such as core-collapse supernova and the course of the ensuing nucleosynthesis processes, such as the r-process. [Copyright &y& Elsevier]

Published
2007
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5. Mass scaling of reaction mechanisms in intermediate energy heavy ion collisions

Author

R. Dayras, A. Demeyer, M. Parlog, B. Tamain, F. Saint-Laurent, Ch.O. Bacri, O. Lopez, Elio Rosato, M.F. Rivet, C. Volant, D. Durand, R. Brou, G. Auger, P. Ecomard, J.L. Charvet, T. Reposeur, L. Lebreton, Bernard Borderie, Richard Laforest, M. Louvel, D. Cussol, V. Métivier, J.F. Lecolley, N. Marie, F. Bocage, R. Legrain, Ph. Eudes, A. Rahmani, L. Tassan-Got, J.C. Steckmeyer, J. Colin, E. Plagnol, A. Le Fèvre, L. Nalpas, R. Bougault, D. Doré, J.P. Wieleczko, D. Gourio, J. Benlliure, P. Lautesse, Ph. Buchet, D. Guinet, Jean Péter, J. L. Laville, A. Chbihi, E. Vient, Laboratoire SUBATECH Nantes (SUBATECH), Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université de Nantes (UN)-Mines Nantes (Mines Nantes), Laboratoire de physique corpusculaire de Caen (LPCC), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3), Grand Accélérateur National d'Ions Lourds (GANIL), Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3), Institut de Physique Nucléaire d'Orsay (IPNO), Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Paris-Sud - Paris 11 (UP11), Institut de Physique Nucléaire de Lyon (IPNL), Centre National de la Recherche Scientifique (CNRS)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3), INDRA, Mines Nantes (Mines Nantes)-Université de Nantes (UN)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Normandie Université (NU)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Université Paris-Sud - Paris 11 (UP11)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Université Claude Bernard Lyon 1 (UCBL), and Université de Lyon-Université de Lyon-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Nuclear reaction, Physics, Nuclear and High Energy Physics, Reaction mechanism, Hot nuclei, 010308 nuclear & particles physics, Reaction mechanisms, Binary number, Decay properties, Energy deposit, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], 01 natural sciences, Mass scaling, Nuclear physics, 25.70.-z, Intermediate energy, 0103 physical sciences, Heavy ion, Nuclear reactions, Atomic physics, Nuclear Experiment, 010306 general physics, Energy (signal processing), Continuous evolution
Abstract

Matière Nucléaire, GANIL E209, GANIL E210; International audience; Reaction mechanisms have been studied for two nearly symmetrical systems of different total mass, between 25 and 74 AMeV. It is shown that collisions are mostly binary whatever the system mass and the bombarding energy. From the slowing-down of the partners, it is possible to establish the continuous evolution from quasielastic to (completely) damped collisions. It turns out that results are independent of the total system mass if involved energies are expressed in AMeV. The occurrence of mid-rapidity emission is also considered and may be used to establish a link between mechanisms observed at low and high bombarding energy. Part of it corresponds to a fast decay of outgoing partners.

Published
2000
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6. Relativistic Random Phase Approximation At Finite Temperature.

Author

Niu, Y. F., Paar, N., Vretenar, D., and Meng, J.

Subjects
*RELATIVISTIC particles, *APPROXIMATION theory, *HARTREE-Fock approximation, *LAGRANGIAN functions, *NUCLEAR physics
Abstract

The fully self-consistent finite temperature relativistic random phase approximation (FTRRPA) has been established in the single-nucleon basis of the temperature dependent Dirac-Hartree model (FTDH) based on effective Lagrangian with density dependent meson-nucleon couplings. Illustrative calculations in the FTRRPA framework show the evolution of multipole responses of 132Sn with temperature. With increased temperature, in both monopole and dipole strength distributions additional transitions appear in the low energy region due to the new opened particle-particle and hole-hole transition channels. [ABSTRACT FROM AUTHOR]

Published
2009
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7. Constraints on the time-scale of nuclear breakup from thermal hard-photon emission

Author

R.W. Ostendorf, S. Schadmand, D. Baiborodin, N. Yahlali, R. Ortega, V. Wagner, David D'Enterria, F. Fernández, H. Delagrange, P. Tlusty, Y. Schutz, J. S. Díaz, R. Turrisi, Herbert Löhner, T. Matulewicz, G. Martınez, H. W. Wilschut, Laboratoire SUBATECH Nantes (SUBATECH), Mines Nantes (Mines Nantes)-Université de Nantes (UN)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Grand Accélérateur National d'Ions Lourds (GANIL), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3), and KVI - Center for Advanced Radiation Technology

Subjects
Nuclear and High Energy Physics, Spinodal, Hadron, Nuclear Theory, FOS: Physical sciences, HEAVY-ION COLLISIONS, MASS, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], Kinetic energy, 7. Clean energy, 01 natural sciences, GAS PHASE-TRANSITION, FERMI ENERGY, Nuclear physics, 0103 physical sciences, Nuclear fusion, ddc:530, Nuclear Experiment (nucl-ex), 010306 general physics, Nuclear Experiment, Physics, GIANT-DIPOLE RESONANCE, MULTIFRAGMENTATION, HOT NUCLEI, 010308 nuclear & particles physics, BREMSSTRAHLUNG PHOTONS, 21.65.+f - 25.70.-z - 13.75.Cs - 64.70.Dv, Breakup, Deuterium, Excited state, COLLECTIVE MOTION, IMPACT PARAMETER, Atomic physics, Impact parameter
Abstract

Measured hard photon multiplicities from second-chance nucleon-nucleon collisions are used in combination with a kinetic thermal model, to estimate the break-up times of excited nuclear systems produced in nucleus-nucleus reactions at intermediate energies. The obtained nuclear break-up time for the $^{129}${Xe} + $^{nat}${Sn} reaction at 50{\it A} MeV is $\Delta$$\tau$ $\approx$ 100 -- 300 fm/$c$ for all reaction centralities. The lifetime of the radiating sources produced in seven other different heavy-ion reactions studied by the TAPS experiment are consistent with $\Delta$$\tau$ $\approx$ 100 fm/$c$, such relatively long thermal photon emission times do not support the interpretation of nuclear breakup as due to a fast spinodal process for the heavy nuclear systems studied., Comment: 11 pages, 9 figures, submitted to EPJA

Published
2006
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8. SEARCH FOR ISOSPIN EFFECTS ON THE LEVEL DENSITY OF NUCLEI INVOLVED IN THE DECAY OF 139Eu

Author

A. Ordine, I. M. Govil, R. Moro, V. Rizzi, M. Barbui, M. Trotta, E. Fioretto, M. Lunardon, G. Prete, G. La Rana, D. Fabris, Nicla Gelli, A. Boiano, M. Cinausero, Franco Lucarelli, A. Brondi, R. Mordente, Emanuele Vardaci, G. La Rana, C. Signorini, S. Shimoura, N., Gelli, F., Lucarelli, Brondi, Augusto, LA RANA, Giovanni, Moro, RENATA EMILIA MARIA, M., Trotta, Vardaci, Emanuele, A., Ordine, A., Boiano, R., Mordente, M., Cinausero, E., Fioretto, G., Prete, M., Barbui, D., Fabri, V., Rizzi, and I., Govil

Subjects
Nuclear physics, Physics, Particle physics, HOT NUCLEI, Isospin, CHARGED PARTICLE EMISSION, ISOSPIN EFFECTS, LEVEL DENSITY
Abstract

Evaporative proton and alpha particle energy spectra and angular distributions have been measured in the decay of the compound nucleus 139Eu produced at an excitation energy of 90 MeV by the 32S + 107Ag reaction. In-plane and out-of-plane angular distributions and energy spectra of alpha particles have been compared with theoretical calculations performed using the statistical Montecarlo code Lilita. Three expressions for the level density parameter have been used: a) without isospin dependence b) with N-Z isospin dependence and c) with Z-Z0 isospin dependence, based on the distance of the nucleus from the valley of stability. The predictions by the Z-Z0 prescription fail to reproduce the data. Isospin independent and N-Z dependence reasonably well reproduce the data.

Published
2005
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9. Dynamical effects on the quasiprojectile temperature in the Ar + Al reaction

Author

Ph. Eudes and Zoran Basrak

Subjects
Nuclear reaction, Physics, Nuclear and High Energy Physics, Hadron, Nuclear fusion, nuclear physics, heavy ions, hot nuclei, Impact parameter, Atomic physics, Nucleon, Nuclear matter, Nuclear Experiment, Spectral line, Reference frame
Abstract

The temperature of the quasiprojectile (QP) emerging from binary collisions of the light Ar + Al system at 65 MeV/nucleon is studied theoretically in the framework of the Landau-Vlasov dynamical model. The slope parameter of a charged-particle kinetic-energy spectrum, calculated in the forward-hemisphere of the QP reference frame, is taken as the apparent temperature. The apparent temperature associated to the true QP emission displays a weak dependence on the impact parameter and the hottest primary QPs are formed at intermediate values of b.

Published
2000

10. Thermal source parameters in Au+Au central collisions at 35 A MeV

Author

G. Vannini, E. Fuschini, T. Glasmacher, F. Gramegna, W. C. Hsi, I. Iori, Graham F. Peaslee, Rinaldo Rui, A. Ferrero, C. P. Montoya, Giacomo Vito Margagliotti, M. Bruno, F. Petruzzelli, P. Désesquelles, M. B. Tsang, M. A. Lisa, J. D. Dinius, M. J. Huang, C. Schwarz, A. S. Botvina, M. L. Fiandri, C. K. Gelbke, P. F. Mastinu, Nicola Colonna, W. G. Lynch, P. M. Milazzo, C. Williams, A. Moroni, D. O. Handzy, M. D'Agostino, L. Phair, P., Désesquelle, M., D'Agostino, A. S., Botvina, M., Bruno, N., Colonna, A., Ferrero, M. L., Fiandri, E., Fuschini, F., Gramegna, I., Iori, Margagliotti, Giacomo, P. F., Mastinu, P. M., Milazzo, A., Moroni, F., Petruzzelli, Rui, Rinaldo, Vannini, Gianni, J. D., Diniu, C. K., Gelbke, T., Glasmacher, D. O., Handzy, W. C., Hsi, M., Huang, M. A., Lisa, W. G., Lynch, C. P., Montoya, G. F., Peaslee, L., Phair, C., Schwarz, M. B., Tsang, C., Williams, Laboratoire de Physique Subatomique et de Cosmologie (LPSC), and Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Institut Polytechnique de Grenoble - Grenoble Institute of Technology-Centre National de la Recherche Scientifique (CNRS)

Subjects
Mass number, Physics, CALIBRATION, Nuclear and High Energy Physics, Thermal source, HOT NUCLEI, 010308 nuclear & particles physics, Statistical model, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], Breakup, 01 natural sciences, STATISTICAL MULTIFRAGMENTATION, Nuclear physics, HEAVY-ION REACTIONS, CSI(TL) SCINTILLATORS, MEV/NUCLEON, BREAKUP, 0103 physical sciences, Calibration, Statistical analysis, Atomic physics, Nuclear Experiment, 010306 general physics, Excitation
Abstract

Central Au+Au collisions at 35 A MeV are analyzed to find the characteristics of a thermal source, in the framework of the statistical multifragmentation model SMM. A recently introduced backtracing protocol provides an effective comparison of theory and experiment. For the first time the distributions of the central source parameters (density, mass number, excitation energy) are found. The collective energy of primary fragments is also deduced. It is shown that the backtracing procedure allows an estimation of the pre-equilibrium emission. (C) 1998 Published by Elsevier Science B.V.

Published
1998

11. Photons in the proton-induced reaction with In at Ep = 50 MeV

Author

J.A. Bordewijk, A. van der Woude, A. Balanda, J. C. S. Bacelar, H. W. Wilschut, A. Krasznahorka, H. van der Ploeg, E. Betak, and R.H. Siemssen

Subjects
Nuclear reaction, Nuclear and High Energy Physics, HIGH-ENERGY, Photon, Proton, NUCLEAR BREMSSTRAHLUNG PRODUCTION, Astrophysics::High Energy Astrophysical Phenomena, Nuclear Theory, ROTATING NUCLEI, HEAVY-ION COLLISIONS, EXCITATION-ENERGY, LARGE VOLUME NAI(TL) SPECTROMETER, Spectral line, CROSS-SECTIONS, Nuclear physics, BREMSSTRAHLUNG CROSS SECTION, P+IN-115, E(P)=50 MEV, COMPOUND-NUCLEUS AND PREEQUILIBRIUM MODEL ANALYSIS, Nuclear Experiment, Physics, GIANT-DIPOLE RESONANCE, HOT NUCLEI, Gamma ray, EXCITED-STATES, Excited state, Giant resonance, Physics::Accelerator Physics, E(P)=50 MEV, MEASURED GDR PARAMETERS, GAMMA-RAY PRODUCTION, Atomic physics, P+IN-115, Radioactive decay
Abstract

Photon emission in proton-induced reactions at 50 MeV with In-115 was studied. Analyses of the measured photon spectrum show that the GDR couples to the compound states as well as to pre-equilibrium states. The centroid and width of the GDR strength function were determined as E(GDR) = 15.4 +/- 0.7 MeV and GAMMA(GDR) = 6.2 +/- 0.5 MeV. From the measured gamma-ray yield above E(gamma) = 30 MeV, a value of (7.1 +/- 1.4) x 10(-5) for the hard-photon emission probability per single proton-neutron collision is inferred.

Published
1994

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