共查询到20条相似文献,搜索用时 15 毫秒
1.
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
2.
E. Gadioli M. Cavinato E. Fabrici E. Gadioli Erba R. Bassini C. Birattari S. Crippa G. F. Steyn S. V. Förtsch J. J. Lawrie F. M. Nortier S. H. Connell E. Sideras-Haddad J. P. F. Sellschop A. A. Cowley 《The European Physical Journal A - Hadrons and Nuclei》2000,8(3):373-376
It is suggested that the spectra of the 8Be ground-state (gs) nuclei produced in the interaction of 12C with 59Co at incident energies varying from 8.3 to 33.3 MeV/amu can be explained by introducing a dissipative friction interaction
mechanism preceding projectile break-up.
Received: 27 March 2000 / Accepted: 11 April 2000 相似文献
3.
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
4.
M. Rejmund K. H. Maier R. Broda B. Fornal M. Lach J. Wrzesiński J. Blomqvist A. Gadea J. Gerl M. Górska H. Grawe M. Kaspar H. Schaffner Ch. Schlegel R. Schubart H. J. Wollersheim 《The European Physical Journal A - Hadrons and Nuclei》2000,8(2):161-164
High-spin states in 202Pb and 203Pb have been investigated by in-beam γ-ray spectroscopy following the reaction 198Pt(9Be,xn). A search for magnetic rotational bands in these isotopes confirmed one of the two bands previously assigned to 202Pb and revealed a new band in this isotope. No evidence for magnetic rotation has been found in 203Pb.
Received: 24 July 2000 / Accepted: 28 September 2000 相似文献
5.
M.?Madurga M. J.G.?Borge H. O.U.?Fynbo B.?Jonson G.?Nyman Y.?Prezado K.?Riisager O.?Tengblad IS-?collaboration TONERRE?collaboration 《The European physical journal. Special topics》2007,150(1):137-138
The aim of this work is to find out the origin of the anomalous
resonance in 8Be seen in the reactions through excited states in 9Be.
We have populated the 9Be excited states by β-decay of 9Li.
Energy and direction of the two α particles has been detected and the
neutron spectra reconstructed. In our work we identified the “anomalous resonance" in
8Be observed in several reaction studies
as coming from the decay of the 2.43 and 2.78 MeV states in 9Be.
This anomalous resonance appears when
the two detected α particles are assumed to form a resonance in 8Be.
We argued that the main decaying channels for these two levels in 9Be do not involve
8Be. 相似文献
6.
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
7.
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
8.
C.A. Gagliardi A. Azhari V. Burjan F. Carstoiu V. Kroha A.M. Mukhamedzhanov A. Sattarov X. Tang L. Trache R.E. Tribble 《The European Physical Journal A - Hadrons and Nuclei》2002,13(1-2):227-232
Peripheral transfer reactions can be used to determine asymptotic normalization coefficients (ANCs). These coefficients, which
specify the normalization of the tail of the nuclear overlap function, determine S-factors for direct capture reactions at astrophysical energies. A variety of proton transfer reactions involving both stable
and radioactive beams have been used to measure ANCs. Tests have demonstrated that ANCs determined from proton transfer reactions
can be used to calculate astrophysical direct capture rates to within 9%. The 10B(7Be, 8B)9Be and 14N(7Be, 8B)13C reactions have been used to measure the ANC appropriate for determining the 7Be(p,γ)8B rate, and the 14N(11C, 12N)13C reaction has been used to measure the ANC required to calculate the 11C(p,γ)12N rate.
Received: 1 May 2001 / Accepted: 4 December 2001 相似文献
9.
10.
T.Yu. Tretyakova D.E. Lanskoy 《The European Physical Journal A - Hadrons and Nuclei》1999,5(4):391-398
Properties of light neutron-rich Λ hypernuclei (16
ΛC, 12
ΛBe, and 11
ΛLi) are calculated within the Skyrme-Hartree-Fock approach. Interplay between hypernuclear interaction features and properties
of these hypernuclei is studied. Response of weakly bound neutron states to hyperon addition depends generally on core distortion
by hyperon, and it is essentially different for the different states. This response is especially sensitive to details of
the ΛN interaction for 1p
1/2 states. Implications of the nuclear spin-orbit potential and nuclear incompressibility in the neutron-rich system properties
are inferred. Dependence of the Λ binding energies in hypernuclei on Z at fixed A is discussed.
Received: 16 December 1998 相似文献
11.
P. Descouvemont 《The European Physical Journal A - Hadrons and Nuclei》2001,12(4):413-419
The 9Be and 9B nuclei are investigated in a microscopic three-cluster model involving α + α +
n (or α + α +
p) configurations. The 8Be (0
+
, 2
+
) +
n and 5He (3/2
-
, 1/2
-
) + α (or mirror) channels are included by taking account of the unstable nature of 8Be and 5He. Spectroscopic properties of 9Be and 9B are analyzed. We show that the 5He + α configurations cannot be neglected to derive accurate results. The 9Be(γ,αα)n photodisintegration cross-section is shown to be mainly determined by 8Be + n channels at low energies, but 5He + α channels become important beyond E
γ≈ 4 MeV.
Received: 7 September 2001 / Accepted: 19 November 2001 相似文献
12.
M. Mazzocco C. Signorini M. Romoli A. De Francesco M. Di Pietro E. Vardaci K. Yoshida A. Yoshida R. Bonetti A. De Rosa T. Glodariu A. Guglielmetti G. Inglima M. La Commara B. Martin D. Pierroutsakou M. Sandoli F. Soramel L. Stroe R. Kanungo N. Khai T. Motobayashi T. Nomura T. Ishikawa H. Ishiyama S. Jeong H. Miyatake M. H. Tanaka I. Sugai Y. Watanabe 《The European Physical Journal A - Hadrons and Nuclei》2006,28(3):295-299
The scattering of the radioactive, weakly bound, halo nucleus 11Be from 209Bi has been studied at 40MeV beam energy. The measurement performed with a low-intensity and a large-emittance secondary beam
could be made using an extremely compact, large solid angle (∼ 2π sr) detecting set-up, based on 8 highly segmented Si telescopes.
The 11, 9Be scattering angular distributions, as well as their relative reaction cross-sections, resulted to be rather similar. This
may suggest that at Coulomb barrier energies the halo structure and the very small binding energy of the 11Be projectile have no big influence on the reaction dynamics. 相似文献
13.
H. Horiuchi 《The European Physical Journal A - Hadrons and Nuclei》2002,13(1-2):39-41
Clustering in light stable and unstable nuclei is discussed. After a brief review of the clustering in stable nuclei, we make
a new prediction of the existence of the alpha cluster condensed states in 12C and 16O. Discussions of clustering in light unstable nuclei are made in the cases of Be and B isotopes up to the neutron dripline.
Received: 1 May 2001 / Accepted: 4 December 2001 相似文献
14.
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
15.
H. Sagawa 《The European Physical Journal A - Hadrons and Nuclei》2002,13(1-2):87-92
I discuss first the effect of decoupling of extended wave functions and the coherence in the low-energy E1 strength in drip line nuclei 12Be and 13O, which are studied by large-scale shell model calculations including 3 ?ω configuration space. The calculated results are
compared to recent experimental data of Coulomb excitations. The quenching of the core polarization charges in drip line nuclei
is also discussed in relation to recent observations of quadrupole moments in B-isotopes.
Received: 1 May 2001 / Accepted: 4 December 2001 相似文献
16.
F. Barranco P.F. Bortignon R.A. Broglia G. Colò E. Vigezzi 《The European Physical Journal A - Hadrons and Nuclei》2001,11(4):385-392
If neutrons are progressively added to a normal nucleus, the Pauli principle forces them into states of higher momentum. When
the core becomes neutron saturated, the nucleus expels most of the wave function of the last neutrons outside to form a halo,
which, because of its large size, can have a lower momentum. It is an open question how nature stabilizes such a fragile system
and provides the glue needed to bind the halo neutrons to the core. Here, we show that this problem is similar to that of
the instability of the normal state of an electron system at zero temperature solved by Cooper, a solution which is at the
basis of BCS theory of superconductivity. By mimicking this approach using, aside from the bare nucleon-nucleon interaction,
the long wavelength vibrations of the nucleus 11Li, the paradigm of halo nuclei, as tailored glues of the least bound neutrons, we are able to obtain a unified and quantitative
picture of the observed properties of 11Li.
Received: 9 May 2001 / Accepted: 17 November 2001 相似文献
17.
C. Gund H. Bauer J. Cub A. Dietrich T. Härtlein H. Lenske D. Pansegrau A. Richter H. Scheit G. Schrieder D. Schwalm 《The European Physical Journal A - Hadrons and Nuclei》2001,10(1):85-95
As a tool for studying the structure of nuclei far off stability the technique of γ-ray spectroscopy after low-energy single-nucleon
transfer reactions with radioactive nuclear beams in inverse kinematics was investigated. Modules of the MINIBALL germanium
array and a thin position-sensitive parallel plate avalanche counter (PPAC) to be employed in future experiments at REX-ISOLDE
were used in a test experiment performed with a stable 36S beam on deuteron and 9Be targets. It is demonstrated that the Doppler broadening of γ lines detected by the MINIBALL modules is considerably reduced
by exploiting their segmentation, and that for beam intensities up to 106 particles/s the PPAC positioned around zero degrees with respect to the beam axis allows not only to significantly reduce
the γ background by requiring coincidences with the transfer products but also to control the beam and its intensity by single
particle counting. The predicted large neutron pickup cross-sections of neutron-rich light nuclei on 2H and 9Be targets at REX-ISOLDE energies of 2.2 MeV .
A are confirmed.
Received: 9 October 2000 / Accepted: 28 January 2001 相似文献
18.
H. Iwasaki T. Motobayashi H. Akiyoshi Y. Ando N. Fukuda H. Fujiwara Zs. Fülöp K. I. Hahn Y. Higurashi M. Hirai I. Hisanaga N. Iwasa T. Kijima A. Mengoni T. Minemura T. Nakamura M. Notani S. Ozawa H. Sagawa H. Sakurai S. Shimoura S. Takeuchi T. Teranishi Y. Yanagisawa M. Ishihara 《The European Physical Journal A - Hadrons and Nuclei》2002,13(1-2):55-58
Experimental studies on in-beam γ-ray spectroscopy using a 12Be radioactive beam are presented. Inelastic scattering of the neutron-rich 12Be nucleus on 208Pb, 12C, and (CH2)n targets has been studied by measuring de-excitation γ-rays in coincidence with scattered particles. The level schemes and
transition probabilities are determined for low-lying excited states in 12Be. The present paper presents a brief review of the spectroscopic results, which may be associated with the N = 8 shell quenching near the drip line.
Received: 1 May 2001 / Accepted: 4 December 2001 相似文献
19.
It is found here that the 1/2+ first excited state of 9Be is a virtual state with the energy of −23.5 KeV. The line shape for the excitation of the state is approximated with a
simple analytic form based on the effective range expansion. The partner in 9B of this state is found to be a resonance with a maximum in the peak at about 1.1 MeV, FWHM of 1.5 MeV, and complex energy
of 0.6 −i0.75 MeV. The line shape for its excitation is calculated in terms of the p−8Be phase shift. The phase shifts are obtained from N−8Be effective potentials deduced from the data on the photodisintegration of 9Be. A possibility for direct extraction of the energy of the resonant state from experimental data is also discussed, and
an expression for a residue at a virtual state pole in terms of a quadrature taken over the virtual state eigenfunction is
given.
Received: 23 March 1998 / Revised version: 3 September 1998 相似文献
20.
N. Soić D. Cali S. Cherubini E. Costanzo M. Lattuada M. Milin Đ. Miljanić S. Romano C. Spitaleri M. Zadro 《The European Physical Journal A - Hadrons and Nuclei》1998,3(4):303-305
Spectra of coincident charged particles from the reactions induced by a 52 MeV 7Li beam incident on a beryllium target were measured. Strong contributions of the 7Li quasi-free scattering off the α-cluster in 9Be nucleus were observed. This observation supports the conclusions from the study of complete fusion of weakly bound light
nuclei at low energies that the “fragility” of the nuclei makes their fusion less probable.
Received: 1 June 1998 相似文献