共查询到20条相似文献,搜索用时 406 毫秒
1.
R.A. Radhi 《The European Physical Journal A - Hadrons and Nuclei》2003,16(3):381-385
Coulomb form factors of C4 transitions in even-even N = Z sd-shell nuclei ( 20Ne, 24Mg, 28Si and 32S) are discussed taking into account higher-energy configurations outside the sd-shell model space which are called core polarization effects. Higher configurations are taken into account through a microscopic
theory, which allows particle-hole excitations from the 1s and 1p shells core orbits and also from the 2s1d-shell orbits to the higher allowed orbits with excitations up to 4 ω. The effect of core polarization is found essential
in both the transition strengths and momentum transfer dependence of form factors, and gives a remarkably good agreement with
the measured data with no adjustable parameters. The calculations are based on the Wildenthal interaction for the sd-shell model space and on the modified surface delta interaction (MSDI) for the core polarization effects.
Received: 24 January 2002 / Accepted: 29 July 2002 / Published online: 6 March 2003
RID="a"
ID="a"e-mail: baguniv@uruklink.net
Communicated by P. Schuck 相似文献
2.
R. A. Radhi 《The European Physical Journal A - Hadrons and Nuclei》2007,34(1):107-111
Inelastic electron scattering form factors away from the closed sd -shell are investigated. This investigation covers the low-lying states in 29Si , which is considered according to the many-particle configuration mixing shell model as the 16O core, plus thirteen nucleons distributed over the entire sd -shell orbits. The investigation concentrates on the perturbative role of the core, which is called core polarization effects,
on the inelastic electron scattering form factors. Core polarization effects are taken into consideration through the excitation
of nucleons from 1s and 1p core orbits, and also from the 2s -1d valence orbits into higher shells, with 2ℏω excitations. Core polarization matrix elements are calculated with the M3Y effective
interaction. For the sd -shell model space, a new Hamiltonian, based on a renormalized G -matrix, USDB, is used. All calculations are performed without adjusting any parameters. 相似文献
3.
Y.H. Zhang M. Oshima Y. Toh M. Koizumi A. Osa T. Shizuma T. Hayakawa M. Sugawara H. Kusakari T. Morikawa S.X. Wen L.H. Zhu 《The European Physical Journal A - Hadrons and Nuclei》2002,13(4):429-433
The 109,111,113Rh nuclei have been produced as fission fragments in the fusion reaction 18O + 208Pb at 85 MeV. Their level schemes have been built from gamma-rays detected using the Euroball IV array. High-spin states of
the neutron-rich 111,113Rh nuclei have been identified for the first time. Several rotational bands with the odd proton occupying the πg
9/2, πp
1/2 and π(g
7/2/d
5/2) sub-shells have been observed. A band of low-energy transitions has been identified at excitation energy around 2 MeV in
109,111Rh, which can be interpreted in terms of three-quasiparticle excitation, πg
9/2νh
11/2νg
7/2/d
5/2. In addition another structure built on states located at low excitation energy (608 keV in 111Rh, 570 keV in 113Rh) points out that, as already observed in the lighter isotopes 107,109Rh, triaxial deformation plays a role in the neutron-rich Rh isotopes well beyond the mid-shell.
Received: 15 July 2002 / Accepted: 9 October 2002 / Published online: 3 December 2002
RID="a"
ID="a"e-mail: porquet@csnsm.in2p3.fr
RID="b"
ID="b"Present address: CSNSM IN2P3-CNRS and Université Paris-Sud 91405 Orsay, France.
RID="c"
ID="c"Present address: CEA/Saclay, DSM/DAPNIA/SPhN, 91191 Gif-sur-Yvette Cedex, France.
Communicated by D. Schwalm 相似文献
4.
D. Sohler Zs. Dombrádi J. Blomqvist J. Cederkäll J. Huijnen M. Lipoglavšek M. Palacz A. Atac C. Fahlander H. Grawe A. Johnson A. Kerek W. Klamra J. Kownacki A. Likar L.-O. Norlin J. Nyberg J. Persson D. Seweryniak G. de Angelis P. Bednarczyk D. Foltescu D. Jerrestam S. Juutinen E. Mäkelä M. de Poli H.A. Roth T. Shizuma Ö. Skeppstedt G. Sletten J. Timár S. Törmänen M. Weiszflog 《The European Physical Journal A - Hadrons and Nuclei》2003,16(2):171-175
Excited states of 99Ag were populated via the 50Cr + 58Ni (261 MeV) reaction using the NORDBALL detector array equipped with charged-particle and neutron detector systems for reaction
channel separation. On the basis of the measured γγ-coincidence relations and angular distribution ratios a significantly
extended level scheme has been constructed up to E
x ∼ 7.8 MeV and I = 35/2. The experimental results were described within the framework of the shell model. Candidates for states fully aligned
in the πg
9/2
-3ν(d
5/2, g
7/2)2 valence configuration space were found at 4109 and 6265 keV.
Received: 18 June 2002 / Accepted: 11 October 2002 / Published online: 4 February 2003
RID="a"
ID="a"e-mail: sohler@atomki.hu
Communicated by J. ?yst? 相似文献
5.
Ts. Venkova M.-G. Porquet I. Deloncle B.J.P. Gall H. De Witte P. Petkov A. Bauchet T. Kutsarova E. Gueorgieva J. Duprat C. Gautherin F. Hoellinger R. Lucas A. Minkova N. Schulz H. Sergolle E.A. Stefanova A. Wilson 《The European Physical Journal A - Hadrons and Nuclei》1999,6(4):405-413
The 107,109Rh nuclei have been produced as fission fragments following the fusion reaction 28Si +176Yb at 145 MeV bombarding energy and studied with the Eurogam2 array. In both nuclei three new rotational bands with the odd
proton occupying the πg9/2, πp1/2 and π(g7/2/d5/2) sub-shells have been observed. In 107Rh, two other bands involving strong M1 transitions have been identified at excitation energy larger than 2 MeV. They can
be interpreted in terms of three quasiparticle excitations. In addition new structures consisting of four transitions, built
on states located at low excitation energy (680 keV in 107Rh and 642 keV in 109Rh), point out the importance of triaxial deformation in these two isotopes.
Received: 1 September 1999 相似文献
6.
Zs. Podolyák P.G. Bizzeti A.M. Bizzeti-Sona S. Lunardi D. Bazzacco A. Dewald A. Algora G. de Angelis E. Farnea A. Gadea D.R. Kasemann T. Klug Th. Kröll S. Lenzi D.R. Napoli C.M. Petrache R. Peusquens C. Rossi Alvarez T. Martinez C.A. Ur 《The European Physical Journal A - Hadrons and Nuclei》2003,17(1):29-36
Lifetimes of excited states in 148Gd were measured using the recoil distance method with a plunger device coupled to the EUROBALL Ge detector array. The differential
decay curve method in coincidence mode allowed the unambiguous determination of lifetimes of more than 20 excited states.
The obtained transition strengths are in good agreement with the shell model calculations. The effect of the Z = 64 subshell closure on the B(E2 : 2+ → 0+) reduced strengths above the N = 82 magic number is discussed.-1
Received: 14 November 2002 / Accepted: 4 February 2003 / Published online: 29 April 2003 相似文献
7.
M. Vatasescu F. Masnou-Seeuws 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2002,21(2):191-204
The paper contains a time-dependent investigation of the tunneling effect observed in the photoassociation spectrum of Cs2 and attributed to the 0g
-(6s, 6p
3/2) double well. When by photoassociation of two cold cesium atoms a vibrational level of the outer well is populated, tunneling
is an efficient mechanism for transferring the population to the inner well (R < 15a
0), where spontaneous emission may lead to formation of cold molecules in low vibrational levels of the a
3Σ+
u(6s, 6s) electronic state. This tunneling effect is analyzed by wavepackets propagation, first considering the double well potential
alone, and following a packet made by a superposition of states initially located at large distances. Characteristic times
for the vibration dynamics, corresponding to a beating phenomenon between the two wells, to partial “revival” at large distances,
and to maxima in the population localized in the inner well are reported and discussed. Second, we simulate the two-channels
a
3Σ+
u(6s, 6s)↦0g
-(6s, 6p
3/2) photoassociation at detunings around 2.9 cm-1: the inner well can be populated either by the excitation of a vibrational level of the external well (resonant excitation),
or by tuning the photoassociation laser at the energy of the inner well level which displays tunneling (“off-resonance excitation”).
In the first case the photoassociation is efficient, while the tunneling probability is small; in the second, the tunneling
probability is large, so that despite the poor efficiency of the photoassociation process, more population can be transferred
to the inner well. This second choice is shown to be very sensitive to the laser intensity, which could be used to control
the population of the inner well and hence the formation of ultracold molecules in low vibrational levels.
Received 19 April 2002 Published online 1st October 2002
RID="a"
ID="a"e-mail: francoise.masnou@lac.u-psud.fr 相似文献
8.
C.M. Marian F. Schneider M. Kleinschmidt J. Tatchen 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2002,20(3):357-367
Electronic spectra of uracil in its diketo (lactam) form and five enol (lactim) tautomeric forms have been investigated by
means of combined density functional and configuration interaction methods. We have simulated the effects of hydrogen bonding
with a protic solvent by recomputing the spectrum of uracil in the presence of two, four, or six water molecules. Geometries
of the electronic ground state and several low-lying excited states have been optimized. Spin-orbit coupling has been determined
for correlated wavefunctions employing a non-empirical spin-orbit mean-field approach. In accord with experiment, we find
the diketo tautomer to be the most stable one. The calculations confirm that the first absorption band arises from the 1( π↦π*) S
0↦S
2 excitation. The experimentally observed vibrational structure in this band originates from a breathing mode of the six ring.
Complexation with water molecules is seen to cause a significant blue shift of n↦π* excitations while leaving π↦π* excitations nearly uninfluenced. Computed radiative lifetimes are presented for the experimentally known weak phosphorescence
from the π↦π* excited T1 state. Among the uracil lactim tautomers, one is particularly interesting from a spectroscopic point of view. In this tautomer,
the π↦π* excitation gives rise to the S1 state.
Received 18 February 2002 / Received in final form 5 June 2002 Published online 13 September 2002 相似文献
9.
T. Hayakawa Y. Toh M. Oshima M. Matsuda Y. Hatsukawa J. Katakura H. Iimura T. Shizuma S. Mitarai M. Sugawara H. Kusakari Y.H. Zhang 《The European Physical Journal A - Hadrons and Nuclei》2002,15(3):299-302
High-spin states of 157Dy were investigated using in-beam γ-ray spectroscopy techniques with a 150Nd(12C, 5n) reaction. Three rotational bands with the h
9/2, i
13/2 and h
11/2 configurations were observed up to (43/2-), 53/2+ and 45/2-, respectively. Interband M1 transitions in the h
11/2 (high-Ω) band were also measured up to the highest-spin state. The high-spin states were well reproduced by calculations
using the tilted-axis-cranking model (TAC). The B(M1)/B(E2) ratio, Routhian and the tilted angle of the angular-momentum vector are found to be in good agreement with the result of
the TAC calculation.
Received: 22 August 2002 / Accepted: 26 September 2002 / Published online: 19 November 2002
RID="a"
ID="a"e-mail: hayakawa@jball4.tokai.jaeri.go.jp
Communicated by W. Henning 相似文献
10.
We study stable “bookshelf” smectic-A structures within a very thin plane-parallel cell of thickness L in which the mismatch between surface preferred (d
s) and intrinsic (d0) smectic layer thicknesses occurs. The Landau-Ginzburg approach based on a complex smectic order parameter is used. For a
weak enough smectic positional anchoring strength W smectic layers adopt the modified bookshelf profile. In a thick enough cell with increasing W a lattice of edge dislocations is continuously formed at the confining surfaces and then depinned from them. The structure
with dislocations is formed when the condition d
0/(
d
0/d
s - 1) ∼ 2 is fulfilled, where is the positional surface anchoring extrapolation length. If the cell is thin enough the dislocations formed at opposite
cell plates annihilate and consequently the smectic layers adopt a locked bookshelf structure. This transition is discontinuous
and takes place when d
0/(L
d
0/d
s - 1) ∼ 5 is realized. To observe these transitions in a cell of thickness L∼ 1μm the conditions W∼ 10-6
J/m
2 and
d
0/d
s - 1∼ 5 . 10-4 have to be fulfilled. All the three qualitatively different structures coexist at the triple point.
Received 21 February 2002 相似文献
11.
J. Huikari M. Oinonen A. Algora J. Cederkäll S. Courtin P. Dessagne L. Fraile S. Franchoo H. Fynbo W.X. Huang A. Jokinen A. Knipper F. Marechal C. Miehé E. Nacher K. Peräjärvi E. Poirier L. Weissman J. Äystö 《The European Physical Journal A - Hadrons and Nuclei》2003,16(3):359-363
The β-decay of 75Sr to its mirror nucleus 75Rb was studied at the ISOLDE PSB facility at CERN by means of β-delayed γ and proton spectroscopy. The decay Q-value and β-delayed γ intensity were measured for the first time. These results, 10.60±0.22 MeV and 4.5+1.9
-0.7%, together with accurate measurements of the β-decay half-life and β-delayed proton branching ratio yielded the Gamow-Teller
strength 0.35±0.05 for the mirror transition. Implications of the results on studies of deformation effects and on the path
of the rapid proton capture process are discussed.
Received: 26 September 2002 / Accepted: 30 October 2002 / Published online: 18 February 2003
RID="a"
ID="a"e-mail: jussi.huikari@phys.jyu.lfi
Communicated by D. Schwalm 相似文献
12.
O. Sorlin C. Donzaud F. Nowacki J.C. Angélique F. Azaiez C. Bourgeois V. Chiste Z. Dlouhy S. Grévy D. Guillemaud-Mueller F. Ibrahim K.-L Kratz M. Lewitowicz S.M. Lukyanov J. Mrasek Yu.-E. Penionzhkevich F. de Oliveira Santos B. Pfeiffer F. Pougheon A. Poves M.G. Saint-Laurent M. Stanoiu 《The European Physical Journal A - Hadrons and Nuclei》2003,16(1):55-61
The neutron-rich nuclei 23
60-63V have been produced at GANIL via interactions of a 61.8A·MeV 76Ge beam with a 58Ni target. Beta-decay to 24
60-63Cr has been investigated using combined β- and γ-ray spectroscopy. Half-lives of the 60-63V nuclei have been determined, and the existence of a beta-decay isomer in the 60V nucleus is strongly supported. The observation of low-energy 2+ states in 60Cr (646keV) and 62Cr (446keV) suggests that these isotopes are strongly deformed with β2 ∼ 0.3. This is confirmed by shell model calculations which show the dominant influence of the intruder g and d orbitals to obtain low 2+ energies in the neutron-rich Cr isotopes.
Received: 13 June 2002 / Accepted: 27 August 2002 / Published online: 17 January 2003
RID="a"
ID="a"e-mail: sorlin@ipno.in2p3.fr
Communicated by D. Guerreau 相似文献
13.
M.V. Ivanov P. Schmelcher 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2001,14(3):279-288
The ground and a few excited states of the beryllium atom in external uniform magnetic fields are calculated by means of our
2D mesh Hartree-Fock method for field strengths ranging from zero up to 2.35×109 T. With changing field strength the ground state of the Be atom undergoes three transitions involving four different electronic
configurations which belong to three groups with different spin projections S
z = 0, - 1, - 2. For weak fields the ground state configuration arises from the 1s
22s
2, S
z = 0 configuration. With increasing field strength the ground state evolves into the two S
z = - 1 configurations 1s
22s2p
-1 and 1s
22p
-13d
-2, followed by the fully spin polarised S
z = - 2 configuration 1s2p
-13d
-24f
-3. The latter configuration forms the ground state of the beryllium atom in the high field regime γ > 4.567. The analogous
calculations for the Be
+ ion provide the sequence of the three following ground state configurations: 1s22s and 1s
22p
-1 (S
z = - 1/2) and 1s2p
-13d
-2 (S
z = - 3/2).
Received 2 October 2000 and Received in final form 8 January 2001 相似文献
14.
M.A. Caprio N.V. Zamfir E.A. McCutchan R.F. Casten Z. Berant H. Amro C.J. Barton C.W. Beausang D.S. Brenner J.R. Cooper R.L. Gill G. Gürdal A.A. Hecht C. Hutter R. Krücken D.A. Meyer J.R. Novak N. Pietralla P.H. Regan J.J. Ressler 《The European Physical Journal A - Hadrons and Nuclei》2003,16(2):177-180
Lifetime measurements for the 2+
1 levels of 162Er and 162Yb were obtained in β+/ɛ decay at the Yale Moving Tape Collector by fast electronic scintillation timing of β+γ coincidences.
Received: 2 September 2002 / Accepted: 1 October 2002 / Published online: 4 February 2003
RID="a"
ID="a"e-mail: mark.caprio@yale.edu
Communicated by J. ?yst? 相似文献
15.
The reaction pn↦dφ is studied within a covariant boson exchange model. The behavior of polarization observables being accessible in forthcoming
experiments near threshold is predicted.
Received: 13 February 2001 / Accepted: 25 March 2002 相似文献
16.
H. Röpke J. Brenneisen M. Lickert 《The European Physical Journal A - Hadrons and Nuclei》2002,14(2):159-167
Eight high-spin states in 36Ar below 10MeV excitation energy, among them a prospective J
π = 8- state at 9408keV and the J? 8 levels of the recently discovered superdeformed rotational band, have been observed by n-γ coincidence measurements with
the 33S(α, nγ) reaction at E
α = 14.4 and 13.4MeV. High-spin assignments of, respectively, J
π = 6+ and 5- were obtained for the E
p = 1209 and 1462keV (E
x = 9682 and 9927keV) resonances of the 35Cl (p,γ) reaction by a measurement of γ-ray angular distributions. The spectrum of the high-spin and of the E
x? 7.4MeV levels is decomposed according to the underlying shell model configurations with n = 0, 1, 2, 4 particles excited from the N = 2 into the N = 3 major shell. The role of four-particle excitations, all connected with large prolate distortions, is elucidated for the
entire A = 36-40 mass region.
Received: 21 December 2001 / Accepted: 25 March 2002 相似文献
17.
L.P. Kaptari B. Kämpfer S.S. Semikh S.M. Dorkin 《The European Physical Journal A - Hadrons and Nuclei》2003,17(1):119-132
The exclusive charge exchange reaction pD↦n(pp) at intermediate and high energies is studied within the Bethe-Salpeter formalism. The final-state interaction in the detected
pp pair at nearly zero excitation energy is described by the 1
S
0 component of the Bethe-Salpeter amplitude. Results of numerical calculations of polarization observables and differential
cross-section persuade that, as in the non-relativistic case, this reaction i) can be utilized as a “relativistic deuteron
polarimeter” and ii) delivers further information about the elementary nucleon-nucleon charge exchange amplitude.
Received: 26 November 2002 / Accepted: 30 January 2003 / Published online: 29 April 2003 相似文献
18.
B. Blank 《The European Physical Journal A - Hadrons and Nuclei》2002,15(1-2):121-124
In recent experiments at GANIL, we studied nuclei at the one- and two-proton drip line. The production rates allowed to search
for direct 2p emission in the drip line nuclei 42Cr, 45Fe, and 49Ni. No evidence for this decay mode was found in 42Cr and 49Ni, whereas the situation stays unclear for 45Fe due to the limited statistics. In the medium-mass region ( A = 50-70), the half-life was measured for all proton-rich nuclei in the range T
z = 0 to T
z = - 1 between Z = 27 and Z = 36. First half-lives were determined for 60Ga, 62Ge, 64As and 66Se. Finally, β-decay studies of the 0+ → 0+ decay of 62Ga have been performed at IGISOL in Jyv?skyl?. Non-analog transitions have been observed and are compared to theoretical predictions.
Received: 21 March 2002 / Accepted: 16 May 2002 / Published online: 31 October 2002
RID="a"
ID="a"e-mail: blank@cenbg.in2p3.fr 相似文献
19.
《The European Physical Journal A - Hadrons and Nuclei》2003,17(2):241-244
The helicity dependence of the γ
p↦pη reaction has been measured for the first time at a center-of-mass angle θ*
η = 70° in the photon energy range from 780 MeV to 790 MeV. The experiment, performed at the Mainz microtron MAMI, used a 4π-detector
system, a circularly polarized, tagged photon beam, and a longitudinally polarized frozen-spin target. The helicity 3/2 cross-section
is found to be small and the results for helicity 1/2 agree with predictions from the MAID analysis.
Received: 19 December 2002 / Accepted: 10 March 2003 / Published online: 20 May 2003 相似文献
20.
M.-G. Porquet Ts. Venkova P. Petkov A. Bauchet I. Deloncle A. Astier N. Buforn J. Duprat B.J.P. Gall C. Gautherin E. Gueorguieva F. Hoellinger T. Kutsarova R. Lucas M. Meyer A. Minkova N. Redon N. Schulz H. Sergolle A. Wilson 《The European Physical Journal A - Hadrons and Nuclei》2002,15(4):463-470
The 106, 108Rh and 110, 112Ag nuclei have been produced as fission fragments following the fusion reaction 28Si + 176Yb at 145 MeV bombarding energy and studied with the Eurogam2 array. The yrast high-spin states of these four odd-odd nuclei,
which are observed for the first time, consist of rotational bands in which the odd proton occupies the πg
9/2 subshell and the odd neutron the νh
11/2 subshell. Their behaviour as a function of spin values does not vary with the number of neutrons: as observed in the odd-N neighbouring nuclei, the motion of the odd neutron remains decoupled from the motion of the core, from N = 61 to N = 65. Moreover, the staggering observed in the yrast bands of odd-odd isotopes is strongly reduced as compared to the large
values displayed by the rotational bands built on the πg
9/2 subshell in the odd-A Rh and Ag isotopes. The results of particle-rotor calculations indicate that this reduction is related to a change of the
core deformation.
Received: 1 June 2001 / Accepted: 23 July 2002 / Published online: 10 December 2002
RID="a"
ID="a"e-mail: porquet@csnsm.in2p3.fr
RID="b"
ID="b"Present address: CSNSM IN2P3-CNRS and Université Paris-Sud 91405 Orsay, France.
RID="c"
ID="c"Present address: NAC, Faure, ZA 7131, South Africa.
RID="d"
ID="d"Present address: Department of Nuclear Physics, ANU, Canberra ACT 0200, Australia.
Communicated by D. Schwalm 相似文献