共查询到20条相似文献,搜索用时 15 毫秒
1.
P. Pawłowski B. Borderie G. Auger Ch.O. Bacri N. Bellaize F. Bocage R. Bougault R. Brou P. Buchet J.L. Charvet A. Chbihi J. Colin D. Cussol R. Dayras A. Demeyer D. Doré D. Durand J.D. Frankland E. Galichet E. Genouin-Duhamel E. Gerlic D. Guinet P. Lautesse J.L. Laville J.F. Lecolley R. Legrain N. Le Neindre O. Lopez M. Louvel A.M. Maskay L. Nalpas A.D. Nguyen M. Pârlog J. Péter E. Plagnol M.F. Rivet E. Rosato F. Saint-Laurent S. Salou J.C. Steckmeyer M. Stern G. Tăbăcaru B. Tamain L. Tassan-Got O. Tirel E. Vient C. Volant J.P. Wieleczko 《The European Physical Journal A - Hadrons and Nuclei》2000,9(3):371-383
The prompt component at intermediate velocity of light charged particles is investigated. An improved coalescence model coupled
to the intra-nuclear cascade code ISABEL is used to obtain light complex particle energy spectra and multiplicities as a function
of impact parameter. The results are compared with experimental data from the 36Ar + 58Ni experiment at 95 MeV/nucleon, performed with the INDRA 4π detection system. The calculated prompt component is found to
rather well reproduce proton spectra. For complex light charged particles the calculated components well populate the high
energy part of spectra. Prompt emission can therefore explain the large transverse energies experimentally observed at mid-rapidity.
Received: 27 July 2000 / Accepted: 20 November 2000 相似文献
2.
E. Gadioli G.F. Steyn C. Birattari M. Cavinato S.H. Connell A.A. Cowley E. Fabrici S.V. Förtsch E. Gadioli Erba J.J. Lawrie F.M. Nortier J.P.F. Sellschop E. Sideras Haddad 《The European Physical Journal A - Hadrons and Nuclei》2001,11(2):161-173
The spectra of 8Begs fragments emitted in the interaction of 100, 200, 300 and 400 MeV 12C with 59Co, 93Nb and 197Au have been measured and analysed. Our analysis suggests that, before breaking up, 12C may suffer a considerable energy loss which increases with increasing incident energy. The amount of excitation energy provided
to the target nucleus in this process increases with decreasing charge of the target nucleus.
Received: 3 May 2001 / Accepted: 5 June 2001 相似文献
3.
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
4.
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
5.
M.I. Adamovich E.S. Basova M.M. Chernyavsky A. Dirner K.G. Gulamov B. Jakobsson L. Just S.P. Kharlamov S.A. Krasnov A. Kravčáková V.G. Larionova S.Z. Nasyrov V.S. Navotny I.D. Ojha G.I. Orlova N.G. Peresadko N.V. Petrov V.V. Rusakova N.A. Salmanova B.K. Singh V. Singh K. Söderström M. TóthovᆠM.I. Tretyakova T.P. Trofimova U.I. Tuleeva S.K. Tuli B.P. Tursunov S. Vokál J. Vrláková B.S. Yuldashev 《The European Physical Journal A - Hadrons and Nuclei》1999,6(4):427-430
Using emulsion detector the collective flow signals in inelastic interactions of 84Kr nuclei with Ag(Br) at 950 MeV/nucleon are studied. A transverse momentum analysis is performed to determine the reaction
plane. The bounce-off of spectator fragments is observed. In azimuthal distributions relative to the reaction plane squeeze-out
and side-splash of participants are seen.
Received: 27 September 1999 相似文献
6.
G. Montagnoli S. Beghini F. Scarlassara A.M. Stefanini L. Corradi C.J. Lin G. Pollarolo Aage Winther 《The European Physical Journal A - Hadrons and Nuclei》2002,15(3):351-356
The two systems 40Ca + 90,96Zr have been studied by measuring nucleon transfer reactions at two energies near the Coulomb barrier, thus complementing
the available sub-barrier fusion cross-sections. Angular distributions for various transfer channels have been determined.
Significantly larger neutron transfer cross-sections are found for the target 96Zr that exhibits the larger enhancement in the sub-barrier fusion cross-sections. All data have been analyzed with a new model
for heavy-ion collisions that calculates simultaneously transfer cross-sections, fusion excitation functions and barrier distributions.
The model gives a good account of both transfer and fusion data.
Received: 2 May 2002 / Accepted: 4 June 2002 / Published online: 26 November 2002
RID="a"
ID="a"e-mail: montagnoli@pd.infn.it, Fax +39049 8277102, Tel. +39049 8277117.
RID="b"
ID="b"On leave from the China Institute for Atomic Energy, 102413 Beijing, China.
Communicated by C. Signorini 相似文献
7.
C. Signorini 《The European Physical Journal A - Hadrons and Nuclei》2002,13(1-2):129-133
The experimental data relative to the interaction for the systems 9, 10, 11Be + 209Bi at the Coulomb barrier are critically discussed and compared also with present theories. The break-up (BU) of the two loosely
bound projectiles, 9, 11Be, seems to influence the fusion process by “hindering” the fusion cross-sections; but, contrary to expectations, the 11Be halo structure has no influence, since no “enhancement” is evident from the existing data. Attempt to describe simultaneously
all the 9Be + 209Bi system data: fusion, elastic scattering and BU, within a coupled-channel (CC) approach is only partly successful. It is
important, from a theoretical viewpoint, to include in the CC formalism as well as possible the BU process both to continuum
states as well as to unbound resonances. More accurate and well-focused experiments are also necessary to pin down this problem.
Received: 1 May 2001 / Accepted: 4 December 2001 相似文献
8.
C. Signorini M. Mazzocco G.F. Prete F. Soramel L. Stroe A. Andrighetto I.J. Thompson A. Vitturi A. Brondi M. Cinausero D. Fabris E. Fioretto N. Gelli J.Y. Guo G. La Rana Z.H. Liu F. Lucarelli R. Moro G. Nebbia M. Trotta E. Vardaci G. Viesti 《The European Physical Journal A - Hadrons and Nuclei》2001,10(3):249-253
Large cross-section reaction channels were measured in the systems 6Li( 7Li) + 208Pb with high statistical accuracy at 5(3) energies around the Coulomb barrier from 29 to 39 MeV. These channels were assigned
(mainly) to the breakup of 6Li, very loosely bound, into α + d and to the breakup of 5Li, produced by n-transfer to the target, into α + p and to similar processes with 7Li beam. The cross-sections with 6Li, S
α = 1.475 MeV, are systematically larger than the 7Li ones. This reflects, most likely, the higher binding energy of 7Li, S
α = 2.468 MeV. Theoretical predictions for the 6Li + 208Pb system which include for 6Li breakup to continuum states within a continuum discretized coupled-channels approach (CDCC) and resonant breakup plus n-transfer
with DWBA reproduce the angular distribution shapes but still underestimate the cross-sections by a factor ∼ 3.
Received: 15 January 2001 / Accepted: 3 March 2001 相似文献
9.
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
10.
A. Tumino M. Lattuada S. Romano C. Spitaleri D. Vinciguerra Z. Basrak O.Yu. Goryunov V.V. Ostashko S. Szilner P. Figuera D. Lo Presti C. Petta N. Randazzo S. Reito G.V. Russo S. Tudisco 《The European Physical Journal A - Hadrons and Nuclei》2001,12(3):327-334
High-spin states of 24Mg produced in the 16O + 12C interaction and decaying into the 16Og.s. + 8Beg.s. channel have been observed in the excitation region between 35 and 52 MeV. Spins have been assigned on the basis of the analysis
of the measured angular correlations. Some of these states with positive parity correspond to the known resonances of the
12C( 12C, 8Beg.s.) 16O reaction belonging to the 16O-2α rotational band of 24Mg. Moreover other resonances show up at higher excitation energy with an energy-spin relationship again suggesting a 16O-2α cluster structure for the associated configuration.
Received: 6 July 2001 / Accepted: 16 October 2001 相似文献
11.
S. Momota M. Kanazawa A. Kitagawa S. Sato Y. Nojiri 《The European physical journal. Special topics》2007,150(1):315-316
The longitudinal and transverse momentum (PL and PYenT) distributions of projectile-like fragments, which were produced with an Ar beam and various targets (C, Al, Nb, Tb, Au),
were measured at E=290A MeV. No significant target effects are found in P L distribution. The width of PT distribution increases with target mass. It is plausible that this result is explained by the deflection of orbit arising
from Coulomb repulsion. The nuclear structural effects are observed in isotopic and isotonic distributions of production cross-sections
of fragments, which are derived from observed momentum distributions. 相似文献
12.
E. Gadioli G.F. Steyn F. Albertini C. Birattari M. Cavinato S.H. Connell A.A. Cowley E. Fabrici S.V. Förtsch E. Gadioli Erba J.J. Lawrie M. Pigni J.P.F. Sellschop E. Sideras Haddad 《The European Physical Journal A - Hadrons and Nuclei》2003,17(2):195-212
In this paper we study the emission of 8Begs, B and N fragments in the interaction of 16O ions with 59Co, 93Nb and 197Au at incident energies varying from 6 to 25 MeV/nucleon. The spectra of these fragments, as well as those of C fragments
studied in a previous paper, are dominated at forward angles by a component originating from break-up of 16O. At the higher incident energies break-up occurs after quite a sizeable projectile energy loss. Another mechanism which
dominates at large emission angles, favours the emission of low-energy fragments and is attributed to the coalescence of nucleons
during the cascade of nucleon-nucleon interactions by means of which the excited nuclei produced in the primary two-ion interaction
thermalize.
Received: 21 January 2003 / Accepted: 27 March 2003 / Published online: 5 June 2003 相似文献
13.
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
14.
E. Z. Buthelezi F. Cerutti E. Gadioli G. F. Steyn A. Pepe S. H. Connell A. A. Cowley 《The European Physical Journal A - Hadrons and Nuclei》2006,28(2):193-203
The excitation functions for production of 48 residues in the interaction of 16O with 103Rh have been measured at incident energies varying from about 40 to 400MeV. Their analysis shows that many competing reaction
mechanism contribute to the formation of these residues including complete fusion, break-up-fusion reactions and 16O inelastic scattering. The cross-sections of most of these mechanisms are obtained by independent measurements of the spectra
of intermediate-mass fragments observed in the interaction of 16O on 93Nb. The agreement between measured and calculated excitation functions is satisfactory in most of the cases. 相似文献
15.
L. Gialanella D. Rogalla F. Strieder S. Theis G. Gyürki C. Agodi R. Alba M. Aliotta L. Campajola A. Del Zoppo A. D'Onofrio P. Figuera U. Greife G. Imbriani A. Ordine V. Roca C. Rolfs M. Romano C. Sabbarese P. Sapienza F. Schümann E. Somorjai F. Terrasi H.P. Trautvetter 《The European Physical Journal A - Hadrons and Nuclei》2001,11(3):357-370
An excitation function of the ground-state γ0-ray capture transition in 12C (α,γ)16O at θγ = 90° was obtained in far geometry using six Ge detectors, where the study of the reaction was initiated in inverse kinematics
involving a windowless gas target. The detectors observed predominantly the E1 capture amplitude. The data at E = 1.32 to 2.99 MeV lead to an extrapolated astrophysical S factor S
E1(E
0) = 90±15 keV b at E
0 = 0.3 MeV (for the case of constructive interference between the two lowest E1 sources), in good agreement with previous works. However, a novel Monte Carlo approach in the data extrapolation reveals
systematic differences between the various data sets such that a combined analysis of all available data sets could produce
a biased estimate of the S
E1(E
0) value. As a consequence, the case of destructive interference between the two lowest E1 sources with S
E1(E
0) = 8±3 keV b cannot be ruled out rigorously.
Received: 6 June 2001 / Accepted: 26 July 2001 相似文献
16.
W. Nörenberg G. Papp P. Rozmej 《The European Physical Journal A - Hadrons and Nuclei》2000,9(3):327-343
The diabatic approach to dissipative collective nuclear motion is reformulated in the local-density approximation in order
to treat the normal modes of a spherical nuclear droplet analytically. In a first application the adiabatic isoscalar modes
are studied and results for the eigenvalues of compressional (bulk) and pure surface modes are presented as function of density
and temperature inside the droplet, as well as for different mass numbers and for soft and stiff equations of state. We find
that the region of bulk instabilities (spinodal regime) is substantially smaller for nuclear droplets than for infinite nuclear
matter. For small densities below 30% of normal nuclear matter density and for temperatures below 5 MeV all relevant bulk
modes become unstable with similar growth rates. The surface modes have a larger spinodal region, reaching out to densities
and temperatures way beyond the spinodal line for bulk instabilities. Essential experimental features of multifragmentation,
like fragmentation temperatures and fragment-mass distributions (in particular the power-law behavior) are consistent with
the instability properties of an expanding nuclear droplet, and hence with a dynamical fragmentation process within the spinodal
regime of bulk and surface modes (spinodal decomposition).
Received: 4 September 2000 / Accepted: 14 November 2000 相似文献
17.
Yu.E. Penionzhkevich Yu.A. Muzychka S.M. Lukyanov R. Kalpakchieva N.K. Skobelev V.P. Perelygin Z. Dlouhy 《The European Physical Journal A - Hadrons and Nuclei》2002,13(1-2):123-127
The experimentally measured excitation functions for the fission and 4n evaporation channels are presented for the 6He + 209Bi reaction. The secondary 6He beam was produced using the special beam line (Q4DQ-spectrometer) of the U400M accelerator at FLNR, JINR. The comparison
of the obtained experimental data with similar results for the 4He + 209Bi reaction shows that in the case of the 6He + 209Bi reaction a significant enhancement of the cross-section is observed for energies above the barrier. In order to get an
agreement between the experimental data and the theoretical calculations it is necessary to reduce the Coulomb barrier by
15-20% , which corresponds to an increase of the parameter r0 of the nuclear potential up to 1.5-1.6 fm.
Received: 1 May 2001 / Accepted: 4 December 2001 相似文献
18.
19.
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
20.
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