共查询到20条相似文献,搜索用时 15 毫秒
1.
2.
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.
Received: 28 April 2000 / Accepted: 27 October 2000 相似文献
3.
C. Muri R.M. Anjos R. Cabezas P.R.S. Gomes S.B. Moraes A.M.M. Maciel G.M. Santos J. Lubian M.M. Sant'Anna C. Tenreiro R. Liguori Neto J.C. Acquadro P.A.B. Freitas 《The European Physical Journal A - Hadrons and Nuclei》1998,1(2):143-149
Elastic and inelastic scattering differential cross sections were measured in the energy range 30 MeV ≤ E
lab
≤ 55 MeV, for the 14N +59Co system. Ambiguities of the optical potential derived from the analysis of the elastic scattering data were removed by performing
calculations at the radius of sensitivity and by comparison with the available fusion cross section data. A simultaneous analysis
of the three mechanisms was performed by coupled channel calculations, and a unique energy independent nuclear potential was
found to be able to fit the data. Discussions and comparisons concerning the optical model, the threshold anomaly, full and
approximated coupled channel calculations are presented.
Received: 6 February 1997 / Revised version: 1 August 1997 相似文献
4.
Rajeev K. Puri Manoj K. Sharma Raj K. Gupta 《The European Physical Journal A - Hadrons and Nuclei》1998,3(3):277-280
A systematic study of isotopic dependence of fusion cross-section is carried out by adding neutrons gradually to N=Z colliding
nuclei. We find that fusion barrier position increases and height decreases, both linearly with the increase of N/Z ratio
of the compound system. The increase in barrier position is larger compared to decrease in barrier height. In terms of these
linear relationships, a parameterized form of fusion cross-sections is given for the neutron-rich colliding nuclei. The fusion
cross-sections are also enhanced linearly with the N/Z ratio, and this enhancement is larger for lower incident centre-of-mass
energies and independent of the choice of reaction partners. Experimental data and other theoretical studies are called for
to verify these results.
Received: 27 February 1998 / Revised version: 22 May 1998 相似文献
5.
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
6.
7.
R. Arora R. K. Puri R. K. Gupta 《The European Physical Journal A - Hadrons and Nuclei》2000,8(1):103-114
We analyse the fusion cross-sections, calculated by using two different analytical parameterisations and compare them with
the experimental data. Both the parameterisations are based on ion-ion potentials calculated within the framework of Skyrme
energy density formalism. In the first case, the ion-ion potential (including the spin-density term) was parameterised and
then, by adding the Coulomb potential, one could compute the fusion barrier analytically. In the second case, the calculated
fusion barrier heights and positions were parameterised directly. Both of these (previously) reported parameterisations are
used here to calculate the fusion barriers and fusion excitation functions for more than 50 reactions belonging to the s-d and f-shell nuclei. A detailed comparison of these parametrisations with the experimental and several other theoretical results
shows that both of these parameterisations are able to reproduce the experimental data equally well. As the (second) direct
parameterisation depends only on the charges and masses of colliding nuclei, it is very useful for predicting/ understanding
the fusion process in low energy heavy-ion reactions.
Received: 24 February 1999 / Accepted: 16 March 2000 相似文献
8.
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
9.
Yong-Xu Yang Jin-Li Zhou Qing-Run Li 《The European Physical Journal A - Hadrons and Nuclei》2007,32(1):35-41
Based on an α-particle model of 12C, an optical potential for intermediate-energy proton- 12C scattering is presented in the framework of the KMT theory. The parameterized proton- 4He amplitude, the required basic input for constructing the optical potential, is obtained by fitting the proton- 4He scattering data. The differential cross-sections and analyzing powers of the proton- 12C elastic scattering at incident energies ranging from 0.2 to 1.0GeV have been calculated by using the obtained optical potential.
The main features of the measured angular distributions of the cross-section and the analyzing power can be satisfactorily
described. The proton- 12C total cross-sections have also been calculated, and the results are in good agreement with the experimental data at energies
below 0.6GeV but underestimate the data about 6% at higher energies. 相似文献
10.
It is found that the scattering of the fragile nucleus 6Li from 12C
and 16O is unexpectedly transparent.
It is shown that the internal-wave
contribution is significantly large in the scattering,
which suggests that some transparency could persist in the scattering
involving the fragile nucleus 6He. 相似文献
11.
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
12.
V.P. Mikhailyuk 《The European Physical Journal A - Hadrons and Nuclei》2000,9(4):473-477
The differential cross-section for elastic scattering of deuterons at 700 MeV, 6Li and 6He at 2.07 GeV nuclei on 12C nucleus is calculated under the assumption of two-cluster (for deuterons and 6Li) and three-cluster (for 6He) structure of incident particle. For 6Li-12C and 6He-12C elastic scattering it is shown that there are quantitative distinctions in the behaviour of the observables calculated in
the above approaches.
Received: 13 October 1999 / Accepted: 3 January 2001 相似文献
13.
14.
D. Pierroutsakou A. Boiano A. De Rosa M. Di Pietro G. Inglima M. La Commara Ruhan Ming B. Martin R. Mordente A. Ordine F. Rizzo V. Roca M. Romoli M. Sandoli F. Soramel L. Stroe M. Trotta E. Vardaci 《The European Physical Journal A - Hadrons and Nuclei》2003,17(1):71-76
The 32S + 100Mo and 36S + 96Mo fusionlike reactions were studied at incident energy of E
lab = 298 MeV and 320 MeV, respectively, with the aim of probing the influence of the entrance channel charge asymmetry on the
dipole γ-ray emission. The excitation energy and spin distribution of the compound nucleus created in these reactions were
identical, the only difference being associated with the unequal charge asymmetry of the two entrance channels. High-energy
γ-rays were detected in an array of 9 seven-pack BaF2 clusters. Coincidence with fusionlike residues detected in four PPAC ensured the selection of central reaction events. By
studying the differential γ-ray multiplicity associated with the two reactions it was shown that the dipole strength excited
in the compound nucleus increases with the entrance channel charge asymmetry. From the linearized spectra, the increase of
the GDR γ-ray intensity was found to be ∼ 25% for the more charge asymmetric system. The results are discussed and compared
with those of previous data obtained at different incident energies.
Received: 21 October 2002 / Accepted: 23 December 2002 / Published online: 1 April 2003 相似文献
15.
A. T. Rudchik V. O. Romanyshyn E. I. Koshchy A. Budzanowski K. W. Kemper K. Rusek V. D. Chesnokova J. Choiński B. Czech L. Głowacka S. Kliczewski V. M. Kyryanchuk S. Yu. Mezhevych A. V. Mokhnach O. A. Momotyuk O. A. Ponkratenko R. Siudak I. Skwirczyńska A. Szczurek 《The European Physical Journal A - Hadrons and Nuclei》2007,33(4):317-325
Angular distributions of the 7Li + 10B elastic and inelastic scattering were measured at the energy E
lab (10B) = 51 MeV (21 MeV c.m.). These and previously measured 7Li + 10B elastic-scattering data known at the 7Li-beam energies 24 MeV (14.1 MeV c.m.) and 39 MeV (22.94 MeV c.m.) were analyzed within the optical model and coupled-reaction
channels method to determine the energy dependence of the parameters of the scattering potential and find the difference of
these parameters from that of 7Li + 11B scattering. It was found that the 7Li + 11B potential parameters fail to describe the 7Li + 10B scattering data. The biggest difference is observed between the depths of the imaginary potentials that describe these scatterings. 相似文献
16.
We obtain a closed-form expression for the distribution of fusion barriers for vibrational nuclei using a generalization of
Dasso, Landowne, and Winther's model, which represents the nuclear surface vibrations as a number of harmonic oscillators,
and allows the excitation of an arbitrary number of phonons in the target and/or projectile. We find that this expression
is in reasonable agreement with the average trends of the empirical distributions for the fusion of 16O with 92Zr, 144Sm and 208Pb, but fails to reproduce the double peaking of the distribution for the 144Sm target. Only when we restrict the number of excited phonons to a limited number, we are able to reproduce such discrete
structures. We show that limiting the number of coupled channels, particularly in the case of strong coupling, increases the
spacings between the channel eigenvalues that determine the positions of the peaks of the barrier distribution and modifies
their heights.
Received: 6 March 2000 / Accepted: 31 January 2001 相似文献
17.
D. Pierroutsakou M. Di Toro F. Amorini V. Baran A. Boiano A. De Rosa A. D'Onofrio G. Inglima M. La Commara A. Ordine N. Pellegriti F. Rizzo V. Roca M. Romoli M. Sandoli M. Trotta S. Tudisco 《The European Physical Journal A - Hadrons and Nuclei》2003,16(3):423-435
We report on the results obtained from the study of the 32S + 64Ni and 32S + 58Ni peripheral reactions at incident energies E
lab = 288 MeV and E
lab = 320 MeV, respectively. High-energy γ-rays were detected in an array of 8 seven-pack BaF2 clusters. Coincidence with complex fragments detected in 12 three-stage telescopes ensured the selection of peripheral reaction
events. All of the relevant reaction parameters were kept constant with the exception of the different initial dipole moment
caused by the different entrance channel charge asymmetry. While for quasi-elastic events no N/Z effect was observed in the differential γ-ray multiplicities of the two reactions, for deep-inelastic events a larger dipole
γ-ray emission occurs during the more N/Z asymmetric reaction. A theoretical interpretation based on a collective Bremsstrahlung analysis of the reaction dynamics
is presented.
Received: 26 September 2002 / Accepted: 13 November 2002 / Published online: 6 March 2003
RID="a"
ID="a"e-mail: pierroutsakou@na.infn.it
RID="b"
ID="b"Present address: INFN, Laboratori Nazionali di Legnaro, Padova, Italy.
Communicated by C. Signorini 相似文献
18.
I.V. Krouglov M. Avrigeanu W. von Oertzen 《The European Physical Journal A - Hadrons and Nuclei》2001,12(4):399-404
Using the framework of the coupled reaction channels (CRC) the elastic scattering and the elastic transfer in the system 6He + 4He measured at E = 151 MeV have been analysed. It is shown that the structure observed in the backward range of the angular distributions
is influenced by the interference of the elastic 2n-transfer with a two-step process passing through the 2+ excitation in 6He. The two-neutron transfer mechanism is studied in the microscopic approach and it is found that for the ground-state transition
the one step dominates by a factor 10 over the two-step mechanism at this energy.
Received: 29 October 2001 / Accepted: 4 December 2001 相似文献
19.
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
20.
M. Anikina L. Chkhaidze T. Djobava V. Garsevanishvili L. Kharkhelauri 《The European Physical Journal A - Hadrons and Nuclei》2000,7(1):139-145
The light front analysis of π− mesons in He(Li,C), C-Ne, C-Cu and O-Pb collisions is carried out. The phase space of secondary pions is divided into two
parts in one of which the thermal equilibrium assumption seems to be in a good agreement with the data. Corresponding temperatures
T are extracted and their dependence on (A
P·A
T)1/2 is studied. The results are compared with the predictions of the Quark-Gluon String Model (QGSM). The QGSM satisfactorily
reproduces the experimental data for light and intermediate-mass nuclei.
Received: 29 September 1999 相似文献