共查询到20条相似文献,搜索用时 15 毫秒
1.
We show that coalescence of nucleons emitted prior to thermalization in highly excited nuclei can explain the anomaly of
kinetic energies of helium clusters. A new coalescence algorithm has been included in the statistical approach to nuclear
reactions formerly used to describe intermediate mass fragment production.
Received: 24 September 1999 / Revised version: 22 November 1999 相似文献
2.
We aim to understand the role of momentum-dependent interactions in transverse flow as well as in its disappearance. For the
present study, central collisions involving masses between 24 and 394 are considered. We find that the momentum-dependent
interactions have different impact in lighter colliding nuclei compared to heavier colliding nuclei. In lighter nuclei, the
contribution of the mean field towards flow is smaller compared to heavier nuclei where binary nucleon-nucleon collisions
dominate the scene. The inclusion of momentum-dependent interactions also explains the energy of the vanishing flow in the
12C + 12C reaction which otherwise was not possible with the static hard equation of state. An excellent agreement of our theoretical
attempt is found for balance energy with experimental data throughout the periodic table. 相似文献
3.
L. Vannucci P. Boccaccio A. Bologna R.A. Ricci G. Vannini R. Donà I. Massa J.P. Coffin P. Fintz G. Guillaume F. Jundt F. Rami P. Wagner 《The European Physical Journal A - Hadrons and Nuclei》2000,7(1):65-77
Final states indicating the presence in the reaction of three-body fragmentation processes has been observed in 32S+59Co and 32S+63Cu dissipative collisions at 5.6 A · MeV. Besides the already observed sequential binary process, data analysis reveals the
presence of prompt ternary break-up of the composite system. Indications on the system configuration at the scission have
been deduced by analyzing the event shape in the momentum phase space. The decay appears to occur in a collinear configuration,
one of the produced fragments originating from the neck which connects the other two. In spite of the large energy dissipation,
structure effects in the charge partition seem to affect part of events.
Received: 3 July 1998 / Revised version: 15 October 1999 相似文献
4.
Z. Sosin 《The European Physical Journal A - Hadrons and Nuclei》2001,11(3):311-317
We propose a two-stage, stochastic model of heavy-ion reactions. Nucleons becoming participants by mean-field effects or by
nucleon-nucleon interactions are transferred to definite final states, creating a PLF, a TLF, clusters, or escaping to continuum.
Nucleon transfer probabilities are governed by state densities. In this way different hot particle sources are created which
afterwards decay by particle emission.
Received: 12 March 2001 / Accepted: 20 June 2001 相似文献
5.
P. Lautesse L. Nalpas R. Dayras M. F. Rivet M. Pârlog E. Bisquer B. Borderie R. Bougault P. Buchet J. L. Charvet A. Chbihi M. Colonna A. Demeyer P. Désesquelles J. D. Frankland E. Galichet E. Gerlic D. C. R. Guinet R. Legrain N. Le Neindre O. Lopez L. Manduci A. M. Maskay G. Noguère E. Rosato R. Roy C. Schmitt M. Stern B. Tamain E. Vient M. Vigilante C. Volant J. P. Wieleczko 《The European Physical Journal A - Hadrons and Nuclei》2006,27(3):349-357
Ar + Ni and Ni + Ni collisions are investigated between 32 and around 100A MeV incident energy with the 4π multidetector
INDRA. Fusion cross-sections are found to decrease from ∼ 180mb at 32A MeV to zero above 50A MeV. Other experimental results,
for light systems, are compared. Moreover, theoretical works are discussed and fusion cross-sections, calculated from two
dynamical simulations based on nuclear Boltzmann equation (Boltzmann-Nordheim-Vlasov and Landau-Vlasov models), are also compared
to experimental results. 相似文献
6.
7.
J. Pluta K. Wosińska Z. Basrak G. Bizard B. Benoit P. Désesquelles O. Dorvaux D. Durand B. Erazmus F. Hanappe B. Jakobsson C. Lebrun F.R. Lecolley R. Lednicky P. Leszczyński K. Mikhailov K. Miller B. Noren T. Pawlak M. Przewłocki Ö. Skeppstedt A. Staranowicz A. Stavinskiy L. Stuttgé B. Tamain 《The European Physical Journal A - Hadrons and Nuclei》2000,9(1):63-68
8.
F. Gulminelli W. Trautmann S. J. Yennello Ph. Chomaz 《The European Physical Journal A - Hadrons and Nuclei》2006,30(1):1-3
The purpose and contents of this topical issue, Dynamics and Thermodynamics with Nuclear Degrees of Freedom, which grew out of a series of workshops in the years 2004 and 2005, are introduced. The central topics are the nuclear density
functional, nuclear multi-fragmentation, and nuclear phase transitions. 相似文献
9.
C. Beşliu A. Jipa D. Argintaru C. Argintaru R. Zaharia J. Gabriel Rican M. Iosif 《The European Physical Journal A - Hadrons and Nuclei》1998,1(1):65-75
The problem of the nuclear matter jets in nucleus-nucleus collisions at 4.5 A GeV/c is discussed. The global analysis of
experimental data, namely the sphericity tensor, is used to evidence such jets. The experimental results are compared with
those obtained in the same collisions for hydrodynamic flow and thrust. The experiments have been performed in the frame of
the SKM 200 Collaboration from JINR Dubna.
Received: 20 March 1997 / Revised version: 20 July 1997 相似文献
10.
B. Borderie F. Gulminelli M.F. Rivet L. Tassan-Got M. Assenard G. Auger F. Bocage R. Bougault R. Brou Ph. Buchet J. Colin R. Dayras A. Demeyer J.D. Frankland E. Galichet E. Genouin-Duhamel E. Gerlic M. Germain D. Guinet P. Lautesse J.L. Laville J.F. Lecolley T. Lefort R. Legrain N. Le Neindre M. Louvel A.M. Maskay L. Nalpas A.D. Nguyen M. Parlog E. Plagnol A. Rahmani T. Reposeur E. Rosato F. Saint-Laurent S. Salou J.C. Steckmeyer M. Stern G. Tabacaru B. Tamain O. Tirel D. Vintache C. Volant 《The European Physical Journal A - Hadrons and Nuclei》1999,6(2):197-202
Vaporized sources produced in collisions between 36Ar and 58Ni at 95 MeV per nucleon have been detected with the multidetector INDRA. Complete information concerning the deexcitation
properties of quasi-projectiles, including second moments of chemical composition, is compared to a quantum statistical model
describing a gas of fermions and bosons in thermal and chemical equilibrium. Inclusions in the calculation of all known discrete
levels of nuclear species which deexcite into light particles and of a final state excluded volume interaction are found decisive
to very well reproduce the experimental data, which strongly supports that thermodynamical equilibrium was achieved at freeze-out
for such sources.
Received: 6 April 1999 相似文献
11.
We discuss an improvement to the expression for the heavy-ion reaction cross-section proposed long ago by Karol (P.J. Karol,
Phys. Rev. C 11, 1203 (1975)) which describes the two-ion interaction through the nucleon-nucleon collisions in their overlap region when
they come into contact. This improvement consists in considering the limitations due to the Pauli principle, which at low
incident energies forbids many nucleon interactions, and in including a Coulomb factor. The final expression for which we
also propose a new parametrization reproduces satisfactorily the known reaction cross-sections for many ion combinations using
a global set of parameters. A decomposition of the reaction cross-section into the contributions of peripheral interactions,
as a function of the impact parameter, is also discussed. 相似文献
12.
M. Pârlog G. Tăbăcaru J. P. Wieleczko J. D. Frankland B. Borderie A. Chbihi M. Colonna M. F. Rivet 《The European Physical Journal A - Hadrons and Nuclei》2005,25(2):223-228
Stochastic mean-field simulations for multifragmenting sources at the same excitation energy per nucleon have been performed. The freeze-out volume, a concept which needs to be precisely defined in this dynamical approach, was shown to increase as a function of three parameters: freeze-out instant, fragment multiplicity and system size. 相似文献
13.
M. Di Toro V. Baran M. Colonna V. Greco S. Maccarone M. Cabibbo 《The European Physical Journal A - Hadrons and Nuclei》2002,13(1-2):155-161
In the reaction dynamics of intermediate-energy radioactive beams we can probe highly asymmetric nuclear matter in compressed
as well as dilute phases. In this report some predictions are presented, based on analytical results as well as on reaction
simulations. We suggest a series of experiments with RIB aimed to shed light on isospin properties of nuclear interactions
in the medium.
Received: 1 May 2001 / Accepted: 4 December 2001 相似文献
14.
G. Casini M. Bini S. Calamai R. Laforest P.R. Maurenzig A. Olmi G. Pasquali S. Piantelli G. Poggi F. Saint-Laurent J.C. Steckmeyer A.A. Stefanini N. Taccetti 《The European Physical Journal A - Hadrons and Nuclei》2000,9(4):491-513
Primary and secondary masses of heavy reaction products have been deduced from kinematics and E-ToF measurements, respectively,
for the direct and reverse collisions of 93Nb and 116Sn at 25 AMeV. Light charged particles have also been measured in coincidence with the heavy fragments. Direct experimental
evidence of the correlation of energy-sharing with net mass transfer has been found using information from both the heavy
fragments and the light charged particles. The ratio of hydrogen and helium multiplicities points to a further correlation
of angular momentum sharing with net mass transfer.
Received: 18 September 2000 / Accepted: 2 December 2000 相似文献
15.
R.I. Badran D.J. Parker I.M. Naqib 《The European Physical Journal A - Hadrons and Nuclei》2001,12(3):317-325
Excitation functions for the production of eight radioactive products of the reactions of 7Li on 56Fe have been measured up to E(7
Li) = 89 MeV. Recoil range distributions for these products, together with inclusive proton, deuteron, triton and alpha spectra,
have been measured at energies of 50 and 68 MeV. The α, t and d spectra show characteristic “break-up” components at forward
angles, while the recoil distributions show evidence of complete fusion and incomplete-fusion process 56Fe( 7Li,α) 59Co * . A parallel study on 55Mn shows some evidences of the ( 7Li,t) incomplete-fusion process, but the cross-section for this process is significantly less than for the triton fusion process.
The recoil distributions can be reproduced on the assumption that essentially all the observed break-up fragments are in fact
associated with incomplete fusion, but uncertainties in normalisation leave open the possibility of a significant contribution
of pure break-up. A diffraction model of the ( 7Li,α) transfer process reproduces the observed break-up α spectra with some success.
Received: 29 March 2001 / Accepted: 12 November 2001 相似文献
16.
M. Ostrick 《The European Physical Journal A - Hadrons and Nuclei》2006,30(1):81-108
Dynamical and thermal characterizations of excited nuclear systems produced during the collisions between two heavy ions at
intermediate incident energies are presented by means of a review of experimental and theoretical work performed in the last
two decades. Intensity interferometry, applied to both charged particles (light particles and intermediate mass fragments)
and to uncharged radiation (gamma rays and neutrons) has provided relevant information about the space-time properties of
nuclear reactions. The volume, lifetime, density and relative chronology of particle emission from decaying nuclear sources
have been extensively explored and have provided valuable information about the dynamics of heavy-ion collisions. Similar
correlation techniques applied to coincidences between light particles and complex fragments are also presented as a tool
to determine the internal excitation energy of excited primary fragments as it appears in secondary-decay phenomena. 相似文献
17.
《The European Physical Journal A - Hadrons and Nuclei》2005,23(2):271-278
Small-angle correlations of pairs of protons emitted in central collisions of Ca + Ca, Ru + Ru and Au + Au at beam energies from 400 to 1500MeV per nucleon are investigated with the FOPI detector system at SIS/GSI Darmstadt. Dependences on system size and beam energy are presented which extend the experimental data basis of pp correlations in the SIS energy range substantially. The size of the proton-emitting source is estimated by comparing the experimental data with the output of a final-state interaction model which utilizes either static Gaussian sources or the one-body phase-space distribution of protons provided by the BUU transport approach. The trends in the experimental data, i.e. system size and beam energy dependences, are well reproduced by this hybrid model. However, the pp correlation function is found rather insensitive to the stiffness of the equation of state entering the transport model calculations. 相似文献
18.
A. Bershadskii 《The European Physical Journal A - Hadrons and Nuclei》2000,7(2):225-228
Critical points approach in the frames of multifractal thermodynamics is suggested to interpret the experimental data on
nuclear multifragmentation which come from interactions in nuclear emulsion (in which 197
79Au118 nuclei of energy ∼1 GeV/nucleon break up into fragments) and from the charge distributions of projectile fragments in sulphur
(32S) fragmentation at 200 GeV/nucleon. It is also shown that multifragmentation after macro-solids collisions exhibits properties
analogous to those observed in the nuclear multifragmentation experiments.
Received: 19 October 1999 相似文献
19.
We aim to present the formation of fragments using static as well as momentum-dependent interactions and larger nucleonic
cross-sections. We shall also examine, in detail, the role of momentum correlations in these situations which are close to
the fire-ball as well as to the spectator matter decay. The role of momentum correlations will be studied by imposing an additional
cut in the momentum space. A clear need of a momentum cut is demonstrated in both fire-ball as well as spectator matter physics.
The momentum-dependent interactions and larger cross-sections play a drastic role in peripheral reactions, whereas the role
of momentum cut remains the same in these situations. 相似文献
20.
Feng-Shou Zhang Lie-Wen Chen Wen-Fei Li Zhi-Yuan Zhu 《The European Physical Journal A - Hadrons and Nuclei》2000,9(2):149-152
The squeeze-out flow in reactions of 124Sn + 124Sn and 124Ba + 124Ba at different incident energies for different impact parameters is investigated by means of an isospin-dependent quantum
molecular dynamics model. For the first time, it is found that the more neutron-rich system (124Sn + 124Sn) exhibits weaker squeeze-out flow. This isospin dependence of the squeeze-out flow is shown to mainly result from the isospin
dependence of nucleon-nucleon cross-section and the symmetry energy.
Received: 14 March 2000 / Accepted: 29 September 2000 相似文献