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1.
The isospin dependence of shell closure phenomena is studied for light neutron-rich nuclei within a microscopic self-consistent
approach using the Gogny force. Introducing configuration mixing, 32Mg is found to be dynamically deformed, although the N = 20 spherical shell closure persists at the mean-field level for all N = 20 isotones. In contrast, the N = 28 spherical shell closure is found to disappear for N - Z≥ 10 whereas deformed shell closures are preserved and lead to shape coexistence in 44
S. Configuration mixing shows that the ground state of this nucleus is triaxially deformed. The first 2+ excitation energy Ex = 1.46 MeV and the reduced transition probability B(E2;0+
gs→ 2+
1)= 420 e
2
fm
4 obtained with our approach are in good agreement with experimental data.
Received: 26 July 2000 / Accepted: 30 August 2000 相似文献
2.
H.A. Roth S.E. Arnell D. Foltescu Ö. Skeppstedt J. Blomqvist G. de Angelis D. Bazzacco S. Lunardi 《The European Physical Journal A - Hadrons and Nuclei》2001,10(3):275-287
High-spin level schemes of the N = 80 isotones 146Dy, 147Ho and 148Er have been investigated by in-beam γ-ray spectroscopic methods using the NORDBALL Compton-suppressed multidetector array
including proton and neutron selection. The projectile-target system 58Ni + 92Mo at 260 MeV beam energy has been used to produce the neutron-deficient N = 80 isotones. The previously known schemes have been extended to considerably higher spin and exitation energy, up to I = 23?, E
x≈ 8.9 MeV in 146Dy, I = 53/2?, E
x≈ 8.7 MeV in 147Ho and I = 23?, E
x≈ 9.6 MeV in 148Er. The results are discussed in terms of the spherical shell model. Many of the levels can be described within this framework.
Received: 12 January 2001 / Accepted: 11 April 2001 相似文献
3.
T. Rzaca-Urban W. Urban A. Kaczor J.L. Durell M.J. Leddy M.A. Jones W.R. Phillips A.G. Smith B.J. Varley I. Ahmad L.R. Morss M. Bentaleb E. Lubkiewicz N. Schulz 《The European Physical Journal A - Hadrons and Nuclei》2000,9(2):165-169
Neutron-rich, 88-94Kr nuclei, populated in spontaneous fission of 248Cm, have been studied with EUROGAM 2, by measuring prompt γ-rays. Many new excited states in even-even Kr isotopes have been
identified. For the first time spins and parities were determined experimentally in these nuclei. Our results indicate that
the quadrupole deformation of Kr isotopes will appear only above N = 58, as observed in Sr and Zr nuclei. The newly found 3- level at 1506.4 keV in 90Kr suggests the exsistence of a new region of increased octupole correlations, probably associated with the ν(d
5/2
h
11/2) pair of Δl = Δj = 3 orbitals.
Received: 18 September 2000 / Accepted: 18 October 2000 相似文献
4.
D. Pierroutsakou M. Di Toro F. Amorini V. Baran A. Boiano A. De Rosa A. D'Onofrio G. Inglima M. La Commara A. Ordine N. Pellegriti F. Rizzo V. Roca M. Romoli M. Sandoli M. Trotta S. Tudisco 《The European Physical Journal A - Hadrons and Nuclei》2003,16(3):423-435
We report on the results obtained from the study of the 32S + 64Ni and 32S + 58Ni peripheral reactions at incident energies E
lab = 288 MeV and E
lab = 320 MeV, respectively. High-energy γ-rays were detected in an array of 8 seven-pack BaF2 clusters. Coincidence with complex fragments detected in 12 three-stage telescopes ensured the selection of peripheral reaction
events. All of the relevant reaction parameters were kept constant with the exception of the different initial dipole moment
caused by the different entrance channel charge asymmetry. While for quasi-elastic events no N/Z effect was observed in the differential γ-ray multiplicities of the two reactions, for deep-inelastic events a larger dipole
γ-ray emission occurs during the more N/Z asymmetric reaction. A theoretical interpretation based on a collective Bremsstrahlung analysis of the reaction dynamics
is presented.
Received: 26 September 2002 / Accepted: 13 November 2002 / Published online: 6 March 2003
RID="a"
ID="a"e-mail: pierroutsakou@na.infn.it
RID="b"
ID="b"Present address: INFN, Laboratori Nazionali di Legnaro, Padova, Italy.
Communicated by C. Signorini 相似文献
5.
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
6.
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
7.
V. Olmos de León F. Wissmann P. Achenbach J. Ahrens H.-J. Arends R. Beck P.D. Harty V. Hejny P. Jennewein M. Kotulla B. Krusche V. Kuhr R. Leukel J.C. McGeorge V. Metag R. Novotny A. Polonski F. Rambo A. Schmidt M. Schumacher U. Siodlaczek H. Ströher A. Thomas J. Weiß M. Wolf 《The European Physical Journal A - Hadrons and Nuclei》2001,12(2):207-215
Differential cross-sections for Compton scattering from the proton have been measured at the MAMI tagged photon facility using
the TAPS setup. The data cover an angular range of θlab
γ = 59°-155° and photon energies ranging from 55 MeV to 165 MeV. Our results are in good agreement with those from previous experiments,
but yield higher precision. Using dispersion relations the proton polarizabilities have been determined to be = [11.9±0.5stat.±1.3syst.±0.3mod.] . 10-4
fm
3 and = [1.2±0.7stat.±0.3syst.±0.4mod.)] . 10-4
fm
3. These results confirm the Baldin sum rule which was re-evaluated to be + = [13.8±0.4] . 10-4
fm
3. We can also conclude that there is no significant additional asymptotic contribution to the backward spin polarizability
γπ beyond the t-channel π0-exchange.
Received: 9 January 2001 / Accepted: 13 February 2001 相似文献
8.
R.R. Rodríguez-Guzmán J.L. Egido L.M. Robledo 《The European Physical Journal A - Hadrons and Nuclei》2003,17(1):37-47
The Angular Momentum Projected Generator Coordinate Method, with the quadrupole moment as collective coordinate and the Gogny
force (D1S) as the effective interaction, is used to describe the properties of the ground state and low-lying excited states
of the even-even neon isotopes 20-34Ne, that is, from the stability valley up to the drip line. It is found that the ground state of the N = 20 nucleus 30Ne is deformed but to a lesser extent than the N = 20 isotope of the magnesium. In the calculations, the isotope 32Ne is at the drip line in good agreement with other theoretical predictions. On the other hand, rather good agreement with
experimental data for many observables is obtained.
Received: 19 Novemeber 2002 / Accepted: 24 January 2003 / Published online: 8 April 2003 相似文献
9.
X.H. Zhou M. Oshima Y. Toh Y.H. Zhang Y. Zheng M. Koizumi A. Osa T. Hayakawa Y. Hatsukawa T. Shizuma M. Sugawara 《The European Physical Journal A - Hadrons and Nuclei》2002,15(3):285-289
Based on the systematic investigation of the data available for nuclei with A≥ 40, a Z
1/3-dependence for the nuclear charge radii is shown to be superior to the generally accepted A
1/3 law. A delicate scattering of data around R
c/Z
1/3 is inferred as owing to the isospin effect and a linear dependence of R
c/Z
1/3 on N/Z (or (N - Z)/2) is found. This inference is well supported by the microscopic Relativistic Continuum Hartree-Bogoliubov (RCHB) calculation
conducted for the proton magic Ca, Ni, Zr, Sn and Pb isotopes including the exotic nuclei close to the neutron drip line.
With the linear isospin dependence provided by the data and RCHB theory, a new isospin-dependent Z
1/3 formula for the nuclear charge radii is proposed.
Received: 23 September 2001 / Accepted: 21 January 2002 相似文献
10.
G. Neyens P. Himpe D. L. Balabanski P. Morel L. Perrot M. De Rydt I. Stefan C. Stodel J. C. Thomas N. Vermeulen D. T. Yordanov 《The European physical journal. Special topics》2007,150(1):149-153
This paper reviews recent results from electromagnetic
moment measurements on isotopes in the island of inversion around
N=20. The obtained moments on neutron rich Na, Mg, Al and Si
isotopes allow to draw conclusions on the amount of intruder
components in their ground state wave function, demonstrating a
gradual transition from the normal sd-shell region into the
island of inversion, starting at N=18 for Na, N=19 for Mg and N=20
for Al isotopes. A measurement of the ground state g factor of
35Si (N=21), using a polarized fragment beam at GANIL, is
discussed in more detail. The magnetic moment μ(35Si, Iπ= 7/2-) = (-)1.638(4) μN is consistent with a normal ground
state structure, dominated by a νf7/2 neutron. 相似文献
11.
M. Bender T. Cornelius G.A. Lalazissis J.A. Maruhn W. Nazarewicz P.-G. Reinhard 《The European Physical Journal A - Hadrons and Nuclei》2002,14(1):23-28
Recent mass measurements show a substantial weakening of the binding-energy difference δ2p(Z, N) = E(Z - 2, N) - 2E(Z, N) + E(Z + 2, N) in the neutron-deficient Pb isotopes. As δ2p is often attributed to the size of the proton magic gap, it might be speculated that reduction in δ2p is related to a weakening of the spherical Z = 82 shell. We demonstrate that the observed trend is described quantitatively by self-consistent mean-field models in terms
of deformed ground states of Hg and Po isotopes.
Received: 25 October 2001 / Accepted: 28 February 2002 相似文献
12.
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
13.
J.H. Hamilton A.V. Ramayya J.K. Hwang X.Y. Luo J.O. Rasmussen E.F. Jones X.Q. Zhang S.J. Zhu P.M. Gore T.N. Ginter I.Y. Lee R.V.F. Janssens I. Ahmed J.D. Cole W. Greiner G. Ter-Akopian Yu. Oganessian 《The European Physical Journal A - Hadrons and Nuclei》2002,15(1-2):175-179
With new high statistic data, new isotopes and new high-spin structures are observed in neutron-rich nuclei populated in the
spontaneous fission of 252Cf. The 135Te levels are extended, and many new levels in 139,141Ba observed. The coexistence of collective and single particle-hole states is found in 135Te. The N = 83 135Te and 139Ba show marked differences associated with differences in their particle and hole states. New levels in 141Ba complete evidence for two opposite-parity doublets characteristic of stable octupole deformation. In 114,116Pd a second backbend is observed for the first time in this mass region and the backbend in 118Pd occurs earlier than in 112-116Pd because of a reduction in pairing. Gamma-type vibrational bands are seen up to 13+ to 15+ in 104,106Mo, 108-112Ru, and 112-116Pd. Their behavior reflects prolate to triaxial shapes in these nuclei. The levels of 162,164Gd are observed for the first time. As N increases toward mid-shell at 104, the moments of inertia in N = 100 164Gd show an unexpected decrease compared to N = 98 162Gd. The levels in 162,164Gd form remarkable shifted identical bands with nuclei separated by 2n, 2p, α, and 2α.
Received: 21 March 2002 / Accepted: 16 May 2002 / Published online: 31 October 2002
RID="a"
ID="a"e-mail: j.h.hamilton@vanderbilt.edu 相似文献
14.
G. Migliorini N. Lee V. Rostiashvili T.A. Vilgis 《The European physical journal. E, Soft matter》2001,6(3):259-270
We study the properties of polyelectrolyte chains under different solvent conditions, using a variational technique. The free
energy and the conformational properties of a polyelectrolyte chain are studied by minimizing the free energy FN, depending on N(N - 1)/2 trial probabilities that characterize the conformation of the chain. The Gaussian approximation is considered for
a ring of length 24 < N < 28 and for an open chain of length 50 < N < 200 in poor- and theta-solvent conditions, including a Coulomb repulsion between the monomers. In theta-solvent conditions
the blob size is measured and found in agreement with scaling theory, including charge depletion effects, expected for the
case of an open chain. In poor-solvent conditions, a globule instability, driven by electrostatic repulsion, is observed.
We notice also inhomogeneous behavior of the monomer-monomer correlation function, reminiscence of necklace formation in poor-solvent
polyelectrolyte solutions. A global phase diagram in terms of solvent quality and inverse Bjerrum length is presented.
Received 7 June 2001 and Received in final form 17 October 2001 相似文献
15.
V. V. Anisovich V. A. Nikonov 《The European Physical Journal A - Hadrons and Nuclei》2000,8(3):401-404
In the framework of the dispersion relation N/D-approach, we restore the low-energy
(IJ
PC = 00+ +)-wave amplitude sewing it with the previously obtained K-matrix solution for the region 450-1900 MeV. The restored N/D-amplitude has a pole on the second sheet of the complex-s plane near the
threshold, that is the light -meson.
Received: 21 February 2000 / Accepted: 20 June 2000 相似文献
16.
K. Jessen M. Bergström P. von Brentano A. Dewald B. Herskind H. Meise C. Schumacher G. Sletten O. Stuck D. Weißhaar I. Wiedenhöver J. Wrzesinski 《The European Physical Journal A - Hadrons and Nuclei》1998,2(2):113-114
An in-beam experiment with the reaction 122Sn(27Al,4np) at 127 MeV was performed at the Nordball multi-detector array in Roskilde. It provided evidence for a new high-spin
isomer in 144Sm. This isomer with T
1/2= (2.6 ± 0.5) ns at an excitation energy E
x= 9232 keV seems to belong to a family of isomers of similar configuration in neighbouring N= 82 nuclei.
Received: 16 November 1997 相似文献
17.
K. Kossert M. Camen F. Wissmann J. Ahrens J.R.M. Annand H.-J. Arends R. Beck G. Caselotti P. Grabmayr O. Jahn P. Jennewein M.I. Levchuk A.I. L'vov J.C. McGeorge A. Natter V. Olmos de León V.A. Petrun'kin G. Rosner M. Schumacher B. Seitz F. Smend A. Thomas W. Weihofen F. Zapadtka 《The European Physical Journal A - Hadrons and Nuclei》2003,16(2):259-273
Differential cross-sections for quasi-free Compton scattering from the proton and neutron bound in the deuteron have been
measured using the Glasgow/Mainz photon tagging spectrometer at the Mainz MAMI accelerator together with the Mainz [48]cm
;SPMOslash; × [64]cm NaI(Tl) photon detector and the G?ttingen SENECA recoil detector. The data cover photon energies ranging from [200]MeV
to [400]MeV at θLAB
γ = 136.2°. Liquid deuterium and hydrogen targets allowed direct comparison of free and quasi-free scattering from the proton. The neutron
detection efficiency of the SENECA detector was measured via the reaction p(γ,π+
n). The “free” proton Compton scattering cross-sections extracted from the bound proton data are in reasonable agreement with
those for the free proton which gives confidence in the method to extract the differential cross-section for free scattering
from quasi-free data. Differential cross-sections on the free neutron have been extracted and the difference of the electromagnetic
polarizabilities of the neutron has been determined to be αn - βn = 9.8±3.6(stat)+2.1
-1.1(syst)±2.2(model) in units of [10-4]fm
3. In combination with the polarizability sum αn + βn = 15.2±0.5 deduced from photoabsorption data, the neutron electric and magnetic polarizabilities, αn = 12.5±1.8(stat)+1.1
-0.6(syst)±1.1(model) and βn = 2.7±1.8(stat)+0.6
-1.1(syst)±1.1(model) are obtained. The backward spin polarizability of the neutron was determined to be γ(n)
π = (58.6±4.0)×10-4
fm
4.
Received: 21 August 2002 / Accepted: 16 October 2002 / Published online: 11 February 2003
RID="a"
ID="a"Part of the Doctoral Thesis.
RID="b"
ID="b"Present address: Physikalisch-Technische Bundesanstalt, Bundesallee 100, D-38116 Braunschweig.
RID="a"
ID="a"Part of the Doctoral Thesis.
RID="b"
ID="b"Present address: Physikalisch-Technische Bundesanstalt, Bundesallee 100, D-38116 Braunschweig.
RID="c"
ID="c"Part of the Habilitation Thesis.
RID="d"
ID="d"e-mail: schumacher@physik2.uni-goettingen.de
Communicated by Th. Walcher 相似文献
18.
Y. Fujita H. Fujita T. Adachi G.P.A. Berg E. Caurier H. Fujimura K. Hara K. Hatanaka Z. Janas J. Kamiya T. Kawabata K. Langanke G. Martınez-Pinedo T. Noro E. Roeckl Y. Shimbara T. Shinada S.Y. van der Werf M. Yoshifuku M. Yosoi R.G.T. Zegers 《The European Physical Journal A - Hadrons and Nuclei》2002,13(4):411-418
Under the assumption that isospin is a good quantum number, symmetry is expected for the transitions from the ground states
of T = 1, T
z = ±1 nuclei to the common excited states of the T
z = 0 nucleus situated between the two nuclei. The symmetry can be studied by comparing the strengths of Gamow-Teller (GT)
transitions obtained from a (p, n)-type charge-exchange reaction on a target nucleus with T
z = 1 with those from the β-decay of the T
z = - 1 nucleus. The A = 58 system is the heaviest for which such a comparison is possible. As a part of the symmetry study, we measured the GT
transitions from 58Ni (T
z = 1) to 58Cu (T
z = 0) by using the zero-degree (3
He, t) reaction at 150 MeV/nucleon. With the achieved resolution of 50 keV, many hitherto unresolved GT states have been identified.
The GT transition strengths were obtained for states up to 8 MeV excitation, i.e., near to the Q window limitation ( Q
EC = 9.37 MeV) of the β-decay from 58Zn (T
z = - 1) to 58Cu. The strength distribution is compared with that from shell-model calculations.
Received: 24 November 2001 / Accepted: 30 January 2002 相似文献
19.
F. Azaiez M. Belleguic D. Sohler M. Stanoiu Zs. Dombrádi O. Sorlin J. Timár F. Amorini D. Baiborodin A. Bauchet F. Becker C. Borcea C. Bourgeois Z. Dlouhy C. Donzaud J. Duprat D. Guillemaud-Mueller F. Ibrahim M.J. Lopez R. Lucas S.M. Lukyanov V. Maslov J. Mrazek C. Moore F. Nowacki B.M. Nyakó Yu.-E. Penionzhkevich M.G. Saint-Laurent F. Sarazin J.A. Scarpaci G. Sletten C. Stodel M. Taylor C. Theisen G. Voltolini 《The European Physical Journal A - Hadrons and Nuclei》2002,15(1-2):93-97
The structure of neutron-rich light nuclei around N = 20 and 28 has been investigated at GANIL by means of in-beam gamma-spectroscopy using fragmentation reactions of 36S and 48Ca beams on a Be target. Gamma-decay of relatively high-lying excited states have been measured for the first time in nuclei
around 32Mg and 44S. Level schemes are proposed and discussed for a large number of these neutron-rich nuclei around N = 20 and N = 28.
Received: 21 March 2002 / Accepted: 16 May 2002 / Published online: 31 October 2002
RID="a"
ID="a"e-mail: azaiez@ipno.in2p3.fr 相似文献
20.
B. Pilawa I. Keilhauer G. Fischer S. Knorr J. Rahmer A. Grupp 《The European Physical Journal B - Condensed Matter and Complex Systems》2003,33(3):321-330
The magnetic properties of the cyclic compound [Fe6(bicine)6] LiClO4
. 2MeOH are reported. The cluster Fe6(bicine)6 forms an antiferromagnetically coupled ring structure of Fe III ions. The magnetic susceptibility is measured between 2 and 300 K and yields the exchange coupling of J/k
B = - 27.5±0.5 K. The field dependence of the magnetic moment is studied at 3 and 6 K in magnetic fields up to 5 T. The zero-field
splitting of the first excited spin states with S = 2 and 3 are determined by ESR at 94 GHz. The intra-molecular interactions of the Fe III ions are analyzed and the on-site anisotropy of the Fe III due to the ligand-configuration is determined to d /k
B = - 0.633±0.008K.
Received 28 October 2002 / Received in final form 22 February 2003 Published online 20 June 2003
RID="a"
ID="a"e-mail: bernd@piobelix.physik.uni-karlsruhe.de 相似文献