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1.
K.W. Schmid 《The European Physical Journal A - Hadrons and Nuclei》2002,13(3):319-338
The effects of the restoration of Galilei invariance in the nuclear many-body problem on the electromagnetic properties of
simple bound states are investigated. For this purpose the form factors for elastic electron scattering from the oscillator
ground states of 4He, 16O and 40Ca as well as those for elastic and inelastic electron scattering between various one-hole states with respect to these reference
configurations are computed with and without projection into the center-of-momentum rest frame. It is demonstrated that, in
some cases, the full restoration of Galilei invariance produces results which are considerably different from those obtained
with the usual approximate way to treat the center-of-mass motion. The same holds for the mathematical Coulomb sum rules and
their first and second moments obtained for the above-mentioned nuclei.
Received: 21 February 2001 / Accepted: 20 December 2001 相似文献
2.
E. Guliyev F. Ertuğral A. A. Kuliev 《The European Physical Journal A - Hadrons and Nuclei》2006,27(3):313-320
In this study the scissors mode 1+ states are systematically investigated within the rotational invariant Quasiparticle Random Phase Approximation (QRPA) for
130-136Ba isotopes. We consider the 1+ vibrations generated by the isovector spin-spin interactions and the isoscalar and isovector quadrupole-type separable forces
restoring the broken symmetry by a deformed mean field according to A.A. Kuliev et al. (Int. J. Mod. Phys. E 9, 249 (2000)). It has been shown that the restoration of the broken rotational symmetry of the Hamiltonian essentially decreases
the B(M1) value of the low-lying 1+ states and increases the collectivization of the scissors mode excitations in the spectroscopic energy region. The agreement
between the calculated mean excitation energies as well as the summed B(M1) value of the scissors mode excitations and the available experimental data of 134Ba and 136Ba is rather good. A destructive interference between the orbit and spin part of the M1 strength has been found for barium isotopes near the shell closer. For all the nuclei under investigation, the low-lying
M1 transitions have ΔK = 1 character as it is the case for the well-deformed nuclei. 相似文献
3.
4.
M. Stellpflug M. Johnsson I.D. Petrov T. Halfmann 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2003,23(1):35-42
We have examined the autoionization spectrum of xenon by resonantly enhanced three-photon ionization (2 + 1 REMPI) involving
intermediate states 5p
56p[J = 0, 2]. The properties of the observed autoionization resonances change significantly with the choice of the intermediate
state. For ionization via an intermediate state with predominantly 5p
5(2P3/2) core character, a strong continuum with embedded window-type 5p
5(2P 1/2)nd'-autoionization resonances is observed. For intermediate states, predominantly with 5p
5(2P1/2) core character, both 5p
5(2P 1/2)nd'- as well as 5p
5(2P 1/2)ns'-resonances are present in the spectrum as overlapping, nearly symmetric peaks on a rather weak continuum. Calculations confirm
the significant dependence of the spectral lineshapes upon the excitation pathway to the autoionizing state. The ionization
data are compared with spectra obtained by monitoring third-harmonic generation via autoionizing states without resonant excitation of intermediate states. These spectra also exhibit the signature of both
the nd'- and ns'-resonances.
Received 30 September 2002 Published online 28 January 2003
RID="a"
ID="a"Permanent address: Rostov State University of Transport Communication, 344038, Rostov-on-Don, Russia.
RID="b"
ID="b"e-mail: halfmann@physik.uni-kl.de 相似文献
5.
M. Sugawara Y. Toh T. Czosnyka M. Oshima T. Hayakawa H. Kusakari Y. Hatsukawa J. Katakura N. Shinohara M. Matsuda T. Morikawa A. Seki F. Sakata 《The European Physical Journal A - Hadrons and Nuclei》2003,16(3):409-414
Electromagnetic properties of the low-lying states in a 70Ge nucleus were studied through the multiple Coulomb excitation of a 70Ge beam with a natPb target. Relative γ-ray intensities were measured as a function of emission angle relative to the scattered projectile.
Sixteen E2 matrix elements, including diagonal ones, for 6 low-lying states have been determined using the least-squares search code
GOSIA. The expectation values 〈Q
2〉 of 01
+ and 02
+ states in 70Ge are compared with those in 72, 74, 76Ge. Simple mixing calculations indicate that the 02
+ states in 70Ge and 72Se can be treated as deformed intruder states. It is shown that the deformed intruder becomes the ground state in 74Kr. These interpretations of the 02
+ states in this region are compared with the potential-energy surface calculations by the Nilsson-Strutinsky model, which
allow to interpret the experimental results in a qualitative way from the theoretical point of view.
Received: 2 September 2002 / Accepted: 5 November 2002 / Published online: 25 February 2003
RID="a"
ID="a"e-mail: sugawara@pf.it-chiba.ac.jp
Communicated by D. Schwalm 相似文献
6.
T. Nakamura 《The European Physical Journal A - Hadrons and Nuclei》2002,13(1-2):33-37
We present the recent experimental results on the 6He structure studied by the 6Li(t, 3He)6He reaction at 336 MeV. Above the conspicuous peaks for ground and first excited states for 6He, we have observed a broad structures at E
x∼ 5 MeV, and E
x∼ 15 MeV. The angular distribution of this structure exhibits the dominance of a ΔL = 1 transition, indicating the existence of intruder dipole states at low excitation energies in 6He. A slight admixture of positive-parity states in this structure has been indicated as well.
Received: 1 May 2001 / Accepted: 4 December 2001 相似文献
7.
S. Witte E.J. van Duijn R. Zinkstok W. Hogervorst 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2002,20(2):159-164
With the second and third harmonic of a tunable single-mode cw Ti:S laser, generated inside external enhancement cavities,
high-resolution LIF measurements on several states of Lu I in various parts of the electromagnetic spectrum are performed.
From these measurements, hyperfine structure A and B constants for both 175Lu and 176Lu as well as isotope shifts have been determined for all levels observed in the single-step excitation process. From the
measured A constants, the magnetic hyperfine structure anomaly has been derived for various states.
Received 14 January 2002 Published online 19 July 2002 相似文献
8.
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.
Gamow-Teller (GT) and spin-dipole (SD) states in 208Bi are studied by using self-consistent Hartree-Fock + Tamm-Dancoff approximation taking into account the coupling to the
continuum. Most of SD strength is found at the excitation energy E
x≈ 25MeV with a very broad width, which agrees with recent experimental observations. It is shown that Landau damping effect is responsible
for the large width of SD peak, while the escape width is found to be at most 1MeV. We study also electric dipole (E1) transitions between GT and SD states in 208Bi. Main E1 transitions for 0- and 1- states are found near excitation energy expected from Brink's hypothesis in which SD states are considered as E1 resonances built on the GT state. Calculated E1 transition strengths between GT and SD states are compared with the analytic sum rules within one-particle one-hole (1p-1h)
configuration space and within both 1p-1h and 2p-2h model space.
Received: 11 April 2000 / Accepted: 30 August 2000 相似文献
11.
A. Arima N. Yoshinaga Y.M. Zhao 《The European Physical Journal A - Hadrons and Nuclei》2002,13(1-2):105-107
We investigate the dominance of 0+ states as the lowest states in shell model calculations with random two-body interactions in a single j-shell. We have found an explanation of the large probability of the 0+ ground state.
Received: 1 May 2001 / Accepted: 4 December 2001 相似文献
12.
R. Lucas M.-G. Porquet Ts. Venkova I. Deloncle M. Houry Ch. Theisen A. Astier A. Bauchet S. Lalkovski G. Barreau N. Buforn T.P. Doan L. Donadille O. Dorvaux J. Durell Th. Ethvignot B.P.J. Gall D. Grimwood W. Korten Y. Le Coz M. Meyer A. Minkova A. Prévost N. Redon A. Roach N. Schulz A.G. Smith O. Stézowski B.J. Varley 《The European Physical Journal A - Hadrons and Nuclei》2002,15(3):315-323
The 115, 117, 119, 121In nuclei have been produced as fission fragments in three reactions induced by heavy ions: 12C + 238U at 90MeV bombarding energy, 18O + 208Pb reaction at 85MeV, and 31P + 176Yb at 152MeV. Their level schemes have been built from gamma-rays detected using the EUROBALL III and IV arrays. High-spin
states of 117, 119, 121In nuclei have been identified for the first time. Moreover, isomeric states lying around 2.5MeV have been established in
119, 121In from the delayed coincidences between the fission fragment detector SAPhIR and the gamma array. Most of the observed states
can be described by coupling a proton g
9/2 hole to a Sn core, while the intruder band based on an orbital from the π[g
7/2/d
5/2] sub-shells behaves as the ground-state band of neighbouring Cd isotopes.
Received: 24 May 2002 / Accepted: 11 June 2002 / Published online: 19 November 2002
RID="a"
ID="a"e-mail: porquet@csnsm.in2p3.fr
RID="b"
ID="b"Present address: CEA-DIF, DAM/DCRE/SDE/LDN, 91680 Bruyères-le-Chatel, France.
RID="c"
ID="c"Present address: CSNSM IN2P3-CNRS and Université Paris-Sud 91405 Orsay, France.
RID="d"
ID="d"Present address: CEA/Saclay, DSM/DAPNIA/SPhN, 91191 Gif-sur-Yvette Cedex, France.
Communicated by D. Schwalm 相似文献
13.
We consider the SU(2) Quasilocal Quark Model of the NJL-type including vector and axial-vector four-fermion interaction vertices with derivatives.
The mass spectrum and a set of model-independent relations for the ground and first-excited states are calculated. The chiral-symmetry
restoration sum rules in these channels are imposed for matching to QCD at intermediate energies in order to get a number
of constraints on parameters of the SU(2) QQM.
Received: 15 January 2003 / Accepted: 10 February 2003 / Published online: 29 April 2003 相似文献
14.
The configuration-dependent cranked Nilsson-Strutinsky approach has been employed to study the properties and band structures
at high spin in the Z = N odd-odd nuclei 46V and 50Mn. The observed bands are explained and terminating states are confirmed by the calculations. The calculated and observed
bands are in good agreement without normalization, especially for terminating states. Possible bands with rotation around
the intermediate axis and the effect of γ-deformation on the total energy of several interesting configurations are discussed.
Received: 2 April 2002 / Accepted: 27 January 2003 / Published online: 15 April 2003 相似文献
15.
K.W. Schmid 《The European Physical Journal A - Hadrons and Nuclei》2001,12(1):29-40
The mathematical tools to restore Galilei invariance in the nuclear many-body problem with the help of projection techniques
are presented. For simple oscillator configurations recursion relations for the various elementary contractions are derived.
The method is then applied to simple configurations for the ground states of 4He, 16O and 40Ca as well as to the corresponding one-hole and one-particle states. As a first application the spectral functions and spectroscopic
factors for the above-mentioned doubly even nuclei are investigated. It turns out that the conventional picture of an uncorrelated
system underestimates the single-particle strengths of the hole states from the last occupied shell while that of the higher
excited hole states is overestimated considerably. These results are in complete agreement with those derived by Dieperink
and de Forest using different methods. Similar effects are seen for the particle states which have not been studied before.
All the calculations presented here are performed analytically and thus can be checked explicitly by the interested reader.
Received: 20 February 2001 / Accepted: 11 September 2001 相似文献
16.
Yu.N. Lobach A.D. Efimov A.A. Pasternak 《The European Physical Journal A - Hadrons and Nuclei》1999,6(2):131-140
Lifetimes of excited states in 110Cd have been measured by the Doppler shift attenuation method in the reaction (α,2nγ) at E
α= 25 MeV. Lifetime values for 8 states and lifetime limits for 3 states were obtained. The band structures of 110Cd have been interpreted in terms of a modified version of the interacting boson model (IBM + 2 q.p.). The calculations explain
well the excitation energies and electromagnetic transition probabilities up to J
π= 16+, except for the 10+
1 state. The structural features are discussed in terms of collective and two quasiparticle excitations.
Received: 20 March 1999 / Revised version: 28 May 1999 相似文献
17.
I. Peter W. von Oertzen S. Thummerer H.G. Bohlen B. Gebauer J. Gerl M. Kaspar I. Kozhoukharov T. Kröll M. Rejmund H.J. Wollersheim I.J. Thompson 《The European Physical Journal A - Hadrons and Nuclei》2003,16(4):509-525
At energies below the Coulomb barrier, neutron transfer and Coulomb excitation have been measured in a very heavy asymmetric
nuclear system, in 206Pb + 118Sn. These are semi-magic nuclei showing super-fluid properties. Particle-γ coincidence techniques using 5 Euroball Cluster
detectors (EB), combined in a set-up with the Heidelberg-Darmstadt NaI Crystal Ball (CB), have been used. Position-sensitive
detectors allowed the observation of scattering processes covering angles from 110 up to 150 degrees. The fragments are identified
via the known γ-decays of the lowest excited states using the high resolution of EB. Using the unique feature of the set-up
with the CB, transfer to well-defined final channels with known quantum numbers is selected using the high-efficiency multiplicity
filter of the CB with no second γ-ray, i.e. without feeding. The data are analysed using the semi-classical approach and transfer probabilities are obtained. Coulomb
excitation has been analysed using known transition probabilities. The enhancement is deduced for the two-neutron transfer
populating the low-lying super-fluid 2+ states in 120Sn and 116Sn, while the 2n transition remains in the ground state for the 20NPb nuclei. Large enhancements up to EF ≃ 103 are observed. This is the first observation of neutron pair transfer enhancement for a heavy nuclear binary system with super-fluid
properties with experimentally separated levels. The calculations with microscopic 2-neutron wave functions, with configuration
mixing over six shell model configurations and using the coupled reaction channels approach, reproduce well the observed probabilities
and the enhancement.
Received: 27 August 2002 / Accepted: 9 December 2002 / Published online: 25 March 2003
RID="a"
ID="a"e-mail: oertzen@hmi.de
Communicated by D. Schwalm 相似文献
18.
Y. Toh T. Czosnyka M. Oshima T. Hayakawa H. Kusakari M. Sugawara Y. Hatsukawa J. Katakura N. Shinohara M. Matsuda 《The European Physical Journal A - Hadrons and Nuclei》2000,9(3):353-356
74Ge beam was Coulomb-excited on a natPb target. Ten E2 matrix elements including diagonal matrix elements for 5 low-lying states have been determined using the least-squares search
code GOSIA. The expectation values of the rotational invariants 〈Q
2〉 and 〈cos3δ〉 show the small and triaxial deformation of the two lowest members of the ground-state band , while the 02
+ and 22
+ states are found to be almost spherical.
Received: 31 August 2000 / Accepted: 4 December 2000 相似文献
19.
C.-B. Moon T. Komatsubara Y. Sasaki T. Jumatsu K. Yamada K. Satou K. Furuno 《The European Physical Journal A - Hadrons and Nuclei》2002,14(1):13-16
Excited states of the 119Xe nucleus have been studied by using in-beam γ-ray spectroscopy with the 107Ag ( 16O, p3n) 119Xe fusion-evaporation reaction at a beam energy of 85 MeV. The level scheme of 119Xe has been derived from γ-γ coincidence and γ-γ angular correlation analyses. We have, for the first time, established the
second negative-parity favored and unfavored states built on the 11/2- state, namely the yrare rotational bands in 119Xe. In contrast to the behavior of the yrast bands where the favored states are lying lower in energy, the yrare favored states
were observed to lie above the unfavored band. Such a signature inversion in 119Xe is changed to be normal at I = 12?.
Received: 8 January 2002 / Accepted: 18 April 2002 相似文献
20.
K.-M. Källman M. Brenner V.Z. Goldberg T. Lönnroth P. Manngård A.E. Pakhomov V.V. Pankratov 《The European Physical Journal A - Hadrons and Nuclei》2003,16(2):159-169
The excitation function and angular distributions of elastic α-particle scattering on 28Si have been measured in the laboratory energy range 6-28 MeV using a backscattering technique on a thick target, yielding
a continuous energy distribution. More than 200 narrow states are observed, with widths in the range ∼ 30-100 keV at excitation
energies E
* = 13-32 MeV. Angular distributions at backward angles were measured, and angular momentum values of more than 83 states have
been deduced. The analysis gives spin-parities J
π, α-partial widths Γα and reduced widths of the narrow high-lying resonant states in 32S. The experimentally observed states display both the negative- and the positive-parity rotational-like sequences with seemingly
no parity splitting, a finding which is at variance with most potential-model predictions. The deduced effective moment of
inertia indicates a more extended structure than the ground-state configuration. The observed strength of each ℓ-value is
analyzed in terms of an underlying split doorway state of Lorentzian form, which yields an interpretation as fragmented rotational
α + 28Si states.
Received: 26 June 2000 / Accepted: 16 September 2002 / Published online: 4 February 2003
RID="a"
ID="a"e-mail: kkallman@abo.fi
RID="b"
ID="b"Present address: Swedish Polytechnic, FIN-65200 Vasa, Finland.
Communicated by D. Guerreau 相似文献