共查询到20条相似文献,搜索用时 11 毫秒
1.
E. Costanzo A. Cunsolo A. Foti O.Yu. Goryunov M. Lattuada V.V. Ostashko L. Putaggio S. Romano C. Spitaleri A. Tumino D. Vinciguerra Yu Xian 《The European Physical Journal A - Hadrons and Nuclei》1999,5(1):69-75
8Begs coincidences with 12C, 8Begs and α-particles produced in the 12C +12C interaction at 65 MeV have been measured in a wide in-plane angular range. The 3 −8Begs final state is found to be produced, even if poor statistics prevent any identification of the 16O states involved in the first stage of the process. The 8Begs−α and 8Begs−12C coincidence yields are found to be due to 12C and 16O excited states, decaying into the 8Begs+α and 12C +α systems, respectively.
Received: 15 June 1998 / Revised version: 4 December 1998 相似文献
2.
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
3.
R. Sherr H.T. Fortune B.A. Brown 《The European Physical Journal A - Hadrons and Nuclei》1999,5(4):371-372
Despite a recent suggestion of Chulkov, et al., we find no evidence for a tetra-proton cluster in 20Mg. The binding energy and radius are easily understood without such a cluster.
Received: 14 May 1999 相似文献
4.
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
5.
R.P. Duperray K.V. Protasov A.Yu. Voronin 《The European Physical Journal A - Hadrons and Nuclei》2003,16(1):27-34
The experimental data of the antideuteron production in proton-proton and proton-nucleus collisions are analyzed within a
simple model based on the diagrammatic approach to the coalescence model. This model is shown to be able to reproduce most
of the existing data without any additional parameter.
Received: 18 April 2002 / Accepted: 30 August 2002 / Published online: 17 January 2003
RID="a"
ID="a"e-mail: duperray@isn.in2p3.fr
RID="b"
ID="b"e-mail: protasov@isn.in2p3.fr
RID="c"
ID="c"e-mail: avoronin@aha.ru
Communicated by A. Molinari 相似文献
6.
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
7.
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
8.
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
9.
L.V. Grigorenko R.C. Johnson I.G. Mukha I.J. Thompson M.V. Zhukov 《The European Physical Journal A - Hadrons and Nuclei》2002,15(1-2):125-129
The theoretical approach to the two-proton radioactivity and three-body decays developed in (L.V. Grigorenko, R.C. Johnson,
I.G. Mukha, I.J. Thompson, M.V. Zhukov, Phys. Rev. Lett. 85, 22 (2000) and to be published in Phys. Rev. C) is applied to the range of light nuclear systems. We study nuclear structures,
widths, and momentum correlations for the decay fragments. Strong contradictions with experiment, as well as effects of special
interest, are found in 12O and 16Ne nuclei.
Received: 21 March 2002 / Accepted: 16 May 2002 / Published online: 31 October 2002
RID="a"
ID="a"e-mail: l.grigorenko@surrey.ac.uk 相似文献
10.
N. Itagaki S. Okabe K. Ikeda I. Tanihata 《The European Physical Journal A - Hadrons and Nuclei》2002,13(1-2):43-47
The structure of Be and C isotopes are investigated based on the molecular-orbit (MO) model. The low-lying states are characterized
by several configurations of valence neutrons, which are constructed as combinations of basic orbits. In 10Be, all of the observed positive-parity bands and the negative-parity bands are described within the model. The second 0+ state of 10Be has a large α-α cluster structure, and this is characterized by a (1/2+
σ)2 configuration. An enlargement of the α-α distance due to two-valence neutrons along the α-α axis makes their wave function
smooth and reduces the kinetic energy drastically. Furthermore, the contribution of the spin-orbit interaction due to coupling
between the S
z = 0 and the S
z = 1 configurations, is important. In the ground state of 12Be, the calculated energy exhibits similar characteristics, that the remarkable α clustering and the contribution of the spin-orbit
interaction make the binding of the state with (3/2-
π)2(1/2+
σ)2 configuration properly stronger in comparison with the closed p-shell (3/2-
π)2(1/2-
π)2 configuration. This is related to the breaking of the N = 8 (closed p-shell) neutron magic number. Also, the molecule-like structure of the C isotopes is investigated using a microscopic α+α+α+n+n+ . . . model. The combination of the valence neutrons in the π- and the σ-orbit is promising to stabilize the linear-chain state
against the breathing and bending modes, and it is found that the excited states of 16C are the most promising candidates for such structure.
Received: 1 May 2001 / Accepted: 4 December 2001 相似文献
11.
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
12.
13.
G. Lévai J. Cseh P. Van Isacker 《The European Physical Journal A - Hadrons and Nuclei》2001,12(3):305-308
A supersymmetry scheme is proposed for nuclear cluster systems. The bosonic sector of the superalgebra describes the relative
motion of the clusters, while its fermionic sector is associated with their internal structure. An example of core + α configurations
is discussed in which the core is a p-shell nucleus and the underlying superalgebra is U(4|12). The α-cluster states of the nuclei 20Ne and 19F are analyzed and correlations between their spectra, electric quadrupole transitions, and one-nucleon transfer reactions
are interpreted in terms of U(4|12) supersymmetry.
Received: 14 September 2001 / Accepted: 26 October 2001 相似文献
14.
M. Ito Y. Sakuragi Y. Hirabayashi 《The European Physical Journal A - Hadrons and Nuclei》1999,5(4):373-383
The nuclear reaction dynamics leading to the formation of recently discovered resonance in the mutual-02
+ channel of the 12C+12C inelastic scattering around E
c.m.≃ 32 MeV is studied in terms of the dynamic polarization potential (DPP) induced by the channel coupling among various excited states in 12C. The microscopic 3α cluster-model wave functions are used to generate the 12C−12C diagonal and coupling potentials in the double-folding model. It is found that DPP for the 02
++ 02
+ channel is an unusually strong attractive potential which even exceeds the zeroth-order folding-model potential of this channel
around the nuclear surface region and that the strong coupling between the 02
+ and 22
+ states is predominantly responsible for the unusual DPP in this channel. The effective potential, the sum of the original
folding-model potential and the attractive DPP, is found to generates resonance states in the same energy region as that of
the resonance states generated by the original folding-model potential but the former states are found to be higher-nodal
states having four additional radial nodes. Similar but more moderate property of DPP is also found in the entrance (elastic)
channel. These results suggest that the reaction dynamics of generating the resonance in the 12C(02
+) +12C(02
+) channel may rather differ from that of the simple crossing of the zeroth-order molecular band generated by the potentials
in the entrance and exit channels suggested by the standard band-crossing model.
Received: 17 December 1998 / Revised version: 1 March 1999 相似文献
15.
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
16.
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
17.
M. Mirea 《The European Physical Journal A - Hadrons and Nuclei》1999,4(4):335-341
A fine structure in the 14C decay of 225Ac is predicted quantitatively by accounting dynamical aspects during the disintegration process. Transitions to the excited
states of the daughter nucleus are considered to be mainly directed by the Landau–Zener promotion mechanism in the region
of avoided crossing levels. The level scheme is evaluated with the superasymmetric two–center shell model. The half–lives
are computed considering the cluster decay as a superasymmetric fission process.
Received: 31 July 1998 / Revised version: 27 November 1998 相似文献
18.
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
19.
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
20.
R.M. Freeman F. Haas M.-P. Nicoli A. Morsad Z. Basrak 《The European Physical Journal A - Hadrons and Nuclei》1999,4(3):239-244
It has been noticed that a distinct resemblance exists at large angles among angular distributions measured for reaction
channels at the energies of some resonance-like structures in the 12C+12C and 14C+16O systems. It is pointed out that such forms are typical of a diffraction pattern of a broad band of coherent partial waves.
Received: 5 October 1998 / Revised version: 8 December 1998 相似文献