共查询到20条相似文献,搜索用时 46 毫秒
1.
M. Papa F. Amorini M. Cabibbo G. Cardella A. Di Pietro P. Figuera A. Musumarra G. Pappalardo F. Rizzo S. Tudisco 《The European Physical Journal A - Hadrons and Nuclei》1999,4(1):69-82
Recent experimental results on particles-γ coincidence measurements on the systems 12C +64Ni and 35Cl +64Ni at about 8 MeV/nucleon are interpreted as due to the effect of a Dipole pre-equilibrium emission produced during the damping
of the proton-neutron relative collective motion in very deformed intermediate systems formed in the first instants of the
collision. The pre-equilibrium effects are evaluated through semiclassic kinetic theories and through modified statistical
approach to include non-stationary effects in Fusion processes, Massive Transfer reactions (in the 12C +64Ni system) and in Binary Dissipative reactions (in the 35Cl +64Ni system). In particular the study performed on the dipole molecular component allows to establish a link between the above
phenomenon and the charge and mass transfer process in quasi-peripheral reactions.
Received: 15 April 1998 / Revised version: 8 June 1998 相似文献
2.
L. Wenxin Q. Zhi Z. Lili W. Wanxin L. Qingzhen S. Tongyu S. Ambe Y. Ohkubo M. Iwamoto Y. Kobayashi H. Maeda F. Ambe 《The European Physical Journal A - Hadrons and Nuclei》2000,7(3):397-401
Cross sections for the production of target fragments in the reactions of iron with 135 MeV/nucleon 12C and 80 MeV/nucleon 16O ions have been measured by off-line γ-ray spectroscopy. Through these data, the mass yield distributions have been obtained.
The result of the experiment for the reaction with 135 MeV/nucleon 12C ions is compared with theoretical calculations using the fusion-fragmentation model and the GEMINI code for sequential binary
decay, following a calculation with the fireball model.
Reveived: 24 March 1999 / Revised version: 16 July 1999 相似文献
3.
E. Vardaci G. La Rana A. Brondi R. Moro A. Principe D. Fabris G. Nebbia G. Viesti M. Cinausero E. Fioretto G. Prete F. Lucarelli E.M. Fiore L. Fiore V. Paticchio P.F. Bortignon 《The European Physical Journal A - Hadrons and Nuclei》1998,2(1):55-60
The α-particle emission from the 28Si+170Er fusion-evaporation reaction at 165 and 185 MeV has been measured and compared with published data relative to the pre-scission
emission in the same reaction. The spectra in the two channels exhibit nearly the same shape in the low energy region, whereas
in the high energy region the spectrum for the fusion-evaporation case features a larger apparent temperature. The interpretation
of the difference in shape between the two decay channels is based on statistical model calculations which account for the
effects due to the different length of the decay chain. Statistical model calculations with standard parameters describe well
the gross features of the alpha particle spectra in the fusion-evaporation channel and the proton spectra in the pre-scission
channel. On the contrary, the model predictions seem to overestimate by ≃2 MeV the emission barrier for the alpha particles
in the pre-fission channel. This effect is ascribed to the larger elongation of the nucleus during the fission process. An
average axis ratio b/a∼ 2 for the emitter is suggested.
Received 29 April 1997 / Revised version 10 September 1997 相似文献
4.
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
5.
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
6.
S. Mukherjee A. Sharma S. Sodaye B.S. Tomar A. Goswami S.B. Manohar 《The European Physical Journal A - Hadrons and Nuclei》2001,12(2):199-205
Incomplete fusion reactions were investigated by measuring the excitation functions of nine evaporation residues in 16O + 51V reaction in the beam energy 4-6 MeV/amu, using the well-known recoil catcher technique and gamma-ray spectrometry. The experimental
data were compared with that obtained from Monte Carlo simulation calculations using the PACE2 code. The results indicate
the presence of incomplete fusion process in the production of two alpha emission products. This was further confirmed by
the measurement of recoil range distribution of these isotopes at 96 MeV beam energy. Calculations of the average angular
momentum associated with these products revealed the peripheral nature of these ICF reactions.
Received: 20 June 2001 / Accepted: 11 September 2001 相似文献
7.
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
8.
Low energy single nucleon transfer reactions are proposed as a tool to investigate the structure of nuclei far off stability.
Experimental concepts and conditions are discussed, in particular high resolution γ-ray spectroscopy after single nucleon
pickup reactions. Nuclear structure is described by Skyrme Hartree-Fock calculations including pairing. As representative
examples, binding energies, radii and wave functions for Mg and Sn isotopes are calculated. In the neutron deficient Mg isotopes
a proton skin is found. At the neutron driplines the Mg and Sn isotopes develop extended neutron skins. The nuclear structure
results are used in DWBA and EFR-DWBA transfer calculations. Single nucleon transfer reactions of 32,36Mg and exotic Sn beams on targets ranging from 2H to 24Mg in inverse kinematics are explored. The one-nucleon transfer cross sections decrease strongly for high-Z targets. An impact
parameter analysis shows that the transfer process is selective on the tails of the wave functions. The largest cross sections
are obtained for 2H and 9Be targets at incident energies of E
lab
= 2-5 MeV/u. The energy-momentum dependence is closely related to the special properties of wave functions of weakly bound
states. Two-neutron (p,t) stripping reactions are studied for a 6He projectile. A strong competition of sequential and direct processes is found at low energies.
Received: 1 October 1997 / Revised version: 25 November 1997 相似文献
9.
D.Q. Fang W.Q. Shen J. Feng X.Z. Cai Y.G. Ma H.Y. Zhang P.Y. Hu W.L. Zhan Z.Y. Guo G.Q. Xiao J.X. Li M. Wang J.F. Wang Z.J. Ning J.Q. Wang J.S. Wang Q.J. Wang Z.Q. Chen 《The European Physical Journal A - Hadrons and Nuclei》2001,10(4):381-385
Fragments produced in the reactions of 69 MeV/nucleon 36Ar and 55 MeV/nucleon 40Ar on a Be target have been measured experimentally. The isotopic distributions from fragmentation reaction for both projectiles
are compared with modified statistical abrasion-ablation model calculations. A strong isospin effect exhibits in the fragment
distributions produced in 36Ar and 40Ar fragmentation. Experimental evidence for the disappearance of the isospin effect in the isotopic distributions produced
by projectile fragmentation is observed with the increase of the violence of nuclear reaction.
Received: 15 November 2000 / Accepted: 11 April 2001 相似文献
10.
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
11.
T. Kikuchi T. Motobayashi N. Iwasa Y. Ando M. Kurokawa S. Moriya H. Murakami T. Nishio J. Ruan S. Shirato S. Shimoura T. Uchibori Y. Yanagisawa T. Kubo H. Sakurai T. Teranishi Y. Watanabe M. Ishihara M. Hirai T. Nakamura S. Kubono M. Gai R.H. France III K.I. Hahn T. Delbar P. Lipnik C. Michotte 《The European Physical Journal A - Hadrons and Nuclei》1998,3(3):213-215
We have measured the dissociation of 8B in the Coulomb field of 208Pb at Ein=51.9 MeV/nucleon and extracted the cross section of the 7Be(p,γ)8B reaction at 0.4 ≤ Erel≤ 3 MeV, which is of importance for the 8B solar-neutrino production rate. The extracted astrophysical S17 factors are consistent with our earlier Coulomb dissociation measurement, and agree with the values deduced from the direct
capture measurements by Filippone et al., Vaughn et al. and Hammache et al. The S factor at zero energy was extracted to be
18.9±1.8 eV-b with the help of theoretical energy-dependence.
Received: 15 August 1998 相似文献
12.
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
13.
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
14.
Zhi Yong He Gen Ming Jin Zu Yu Li Li Min Duan Guang Xi Dai Bao Guo Zhang He Yu Wu Wan Xin Wen Yu Jin Qi Qing Zheng Luo Su Fang Wang 《The European Physical Journal A - Hadrons and Nuclei》1998,1(1):61-64
Emission orders of light charged particles and Li fragments from highly excited fissioning nuclei in the reaction of 40Ar+197Au at E
beam
/A=25 MeV have been studied by measuring difference velocity distributions of two correlated particles at small relative angles
in coincidence with two fission fragments. By comparing the data with three-body trajectory calculations, we found that high
velocity deuterons are emitted prior to high velocity Li fragments but low velocity deuterons are emitted after low velocity
Li fragments. On the other hand, no preferential emission was observed among light particles, such as protons and deuterons.
Furthermore, the emission orders are found to depend only weakly on the mass asymmetry of fission fragments.
Received: 3 June 1997 / Revised version: 23 July 1997 相似文献
15.
J. Giovinazzo B. Blank C. Borcea M. Chartier S. Czajkowski G. de France R. Grzywacz Z. Janas M. Lewitowicz F. de Oliveira Santos M. Pfützner M.S. Pravikoff J.C. Thomas 《The European Physical Journal A - Hadrons and Nuclei》2001,11(3):247-249
In an experiment at the SISSI/LISE3 facility of GANIL, the most proton-rich zinc isotopes 55,56Zn have been observed for the first time. The experiment was performed using a high-intensity 58Ni beam at 74.5 MeV/nucleon impinging on a nickel target. The identification of 55,56Zn opens the way to 54Zn, a good candidate for two-proton radioactivity according to theoretical predictions.
Received: 31 October 2000 / Accepted: 9 November 2000 相似文献
16.
B. Krusche J. Ahrens R. Beck M. Fuchs S.J. Hall F. Härter J.D. Kellie V. Metag M. Röbig-Landau H. Ströher 《The European Physical Journal A - Hadrons and Nuclei》1999,6(3):309-324
Photoproduction of neutral pions from the deuteron has been studied for incident photon energies from 200 MeV to 792 MeV
with the TAPS detector at the Mainz MAMI accelerator. Total and differential cross sections covering the full angular range
have been obtained for coherent and incoherent single πo-photoproduction. Good agreement between model predictions and the data was found for the coherent process. The incoherent
cross section in the energy region of the Δ(1232)-resonance is overestimated by existing models. A comparison to model predictions
indicates that final state interaction effects are much more important than for the coherent reaction. However, the angular
dependence of the data in the Δ-peak region follows the pattern expected from the dominant excitation of the M1+-multipole on the free nucleon. The energy and angular dependence of single πo-photoproduction in the second resonance region is remarkably different from the reaction on the free proton, indicating a
strong nuclear effect. Finally the total cross section for double πo-photoproduction from the deuteron has been measured for the first time and was used to estimate the cross section for double
πo-photoproduction from the neutron.
Received: 24 June 1999 / Revised version: 30 August 1999 相似文献
17.
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
18.
I. V. Krouglov W. von Oertzen 《The European Physical Journal A - Hadrons and Nuclei》2000,8(4):501-510
Using the framework of the coupled reaction channels (CRC) the one- and two-neutron transfer process initiated by the weakly
bound nucleus 6He on 12C at an energy of E
L = 5.9 MeV is studied. The absolute cross-sections for a few states in 14C are well reproduced within a factor 2 in second order, using microscopic wave functions of 6He and 12C. Only a small dependence of the cross-section on details of the 6He wave function is observed. Good fits to the data are obtained in a calculation with full coupling (25 iterations) with
renormalised optical potential parameters and spectroscopic amplitudes of 6He.
Received: 13 June 2000 / Accepted: 24 July 2000 相似文献
19.
M.N.A. Abdullah M.S. Mahbub S.K. Das A.S.B. Tariq M.A. Uddin A.K. Basak H.M. Sen Gupta F.B. Malik 《The European Physical Journal A - Hadrons and Nuclei》2002,15(4):477-486
Full finite-range macroscopic calculations in the distorted-wave Born approximation have been performed using the molecular
and Michel α-nucleus potentials to analyze the angular distributions of cross-sections of the 27Al(α, d)29Si reaction, at 26.5 and 27.2 MeV incident energies, leading to seven transitions up to the excitation energy E
X = 4.08 MeV of the final nucleus. The parameters of the two types of the α-nucleus potentials are determined from the elastic-scattering
data. Both the molecular and Michel potentials, without any adjustment to the parameters needed to fit the elastic-scattering
data, are able in most cases to reproduce, simultaneously, the absolute cross-sections particularly at large angles, where
the previous calculations failed to reproduce by orders of magnitude, and the gross pattern of angular distributions of the
reaction. The deuteron-cluster spectroscopic factors for most of the seven transitions, deduced using the two α-27Al potentials, differ from those obtained in earlier works. The spectroscopic factor for the ground-state transition, deduced
in the present work for the 25.8 MeV data, agrees well with the shell model prediction.
Received: 15 July 2002 / Accepted: 8 August 2002 / Published online: 10 December 2002
RID="a"
ID="a"e-mail: akbasak2001@Yahoo.com
Communicated by G. Orlandini 相似文献
20.
R. da Silveira A. Boukour Ch. Leclercq-Willain 《The European Physical Journal A - Hadrons and Nuclei》2000,7(4):503-506
We present a simple method which enables us to identify the occurence of a forward glory in heavy ion scattering data. The
method is successfully applied to the elastic scattering data of 12C (65 MeV), 13C (60 MeV), 15N (85 MeV) and 16O (75 MeV) on 28Si.
Received: 2 July 1999 / Revised version: 3 December 1999 相似文献