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1.
G. Meierhofer P. Kudejova L. Canella P. Grabmayr J. Jochum J. Jolie 《The European Physical Journal A - Hadrons and Nuclei》2009,40(1):61-64
The thermal neutron capture cross-sections of the 76Ge(n,)77Ge and the 76Ge(n,)77m
Ge reactions have been measured by activating targets of isotopically enriched GeO2 through cold neutrons. The -decay spectra after the -decay of 77Ge and 77m
Ge were measured with HPGe detectors. From these spectra the cross-sections for the 76Ge(n,) reactions were derived relative to the cross-section of 197Au using the absolute emission probabilities of the observed -ray energies. The methods used in this work result in smaller systematic uncertainties than those obtained in previous experiments. 相似文献
2.
P. C. Sood O. S. K. S. Sastri R. K. Jain 《The European Physical Journal A - Hadrons and Nuclei》2009,39(1):101-106
The role of the band quantum number K in influencing the character of allowed transitions in heavy deformed nuclei is examined. The conditions for the occurrence of K -forbidden decays in this region are explored. Specific cases of “allowed” decays proceeding via
K = 2 to
K = 6 channels are presented to illustrate the phenomenon. The listed
K = 2 transitions, which by themselves contribute over 10% of all the presently known allowed transitions for A
228 nuclei, are seen to have an average , which is clearly outside the normal range for allowed transitions. It is concluded that, wherever the -connected states can be confidently labelled using the quantum numbers, the K -forbiddenness is in general as significant as that involving the other two (spin and parity) quantum numbers. 相似文献
3.
Essential properties of halo nuclei can be described in terms of a few low-energy constants. For neutron halo nuclei, analytical
results can be found for wave functions and electromagnetic transition matrix elements in simple but well-adapted models.
These wave functions can be used to study nuclear reactions; an especially simple and instructive example is Coulomb excitation.
A systematic expansion in terms of small parameters can be given. We present scaling laws for excitation amplitudes and cross-sections.
The results can be used to analyze experiments like 11Be Coulomb excitation. They also serve as benchmark tests for more involved reaction theories. 相似文献
4.
The low-lying levels in 127La have been studied through the -decay of 127Ce ( T1/2 = 29s) produced by bombarding a natMo target with a 185-MeV 35Cl beam. Reaction products were on-line mass-separated, and -ray singles and - coincidence measurements were performed. Conversion electrons were also measured and multipolarities of transitions have been derived. The half-life of the 210.9-keV level was determined to be (1.9±0.3)ns by the - delayed coincidence technique. The level scheme obtained has been compared with calculations based on the Nilsson model. 相似文献
5.
Comparison between different computational schemes for variational calculations in nuclear structure
G. Puddu 《The European Physical Journal A - Hadrons and Nuclei》2009,39(3):335-340
We compare several iteration methods for angular-momentum- and parity-projected Hartree-Fock calculations. We used the Anderson
update, the modified Broyden method, newly introduced in nuclear-structure calculations, and variants of the Broyden-Fletcher-Goldhaber-Shanno
methods (BFGS). We performed ground-state calculations for 18C and 6Li using the two-body Hamiltonian obtained from the CDBonn-2000 potential via the Lee-Suzuki renormalization method. We found
that BFGS methods are superior to both the Anderson update and to the modified Broyden method. In the case of 6Li we found that the Anderson update and modified Broyden method do not converge to the angular-momentum- and parity-projected
Hartree-Fock minimum. The reason is traced back to the lack of a mechanism that guarantees a decrease of the energy from one
iteration to the next and to the fact that these methods guarantee a stationary solution rather than a minimum of the energy. 相似文献
6.
A superdeformed band has been observed in the N = 108 isotope 190Pb. This is the most neutron-deficient Pb isotope in which superdeformed states have been observed. Several theoretical approaches have predicted that N = 108 will mark the limit of observable superdeformation in the Pb isotopes. The band, which consists of five (possibly six) transitions, is observed to feed at least one isomeric level in its decay to the ground state. This decay pattern supports a spin assignment of 10 for the lowest observed level. 相似文献
7.
Omar Mustafa S. Habib Mazharimousavi 《International Journal of Theoretical Physics》2009,48(1):183-193
Non-Hermitian but
-symmetrized spherically-separable Dirac and Schr?dinger Hamiltonians are considered. It is observed that the descendant Hamiltonians
H
r
, H
θ
, and H
φ
play essential roles and offer some “user-feriendly” options as to which one (or ones) of them is (or are) non-Hermitian.
Considering a
-symmetrized H
φ
, we have shown that the conventional Dirac (relativistic) and Schr?dinger (non-relativistic) energy eigenvalues are recoverable.
We have also witnessed an unavoidable change in the azimuthal part of the general wavefunction. Moreover, setting a possible
interaction V(θ)≠0 in the descendant Hamiltonian H
θ
would manifest a change in the angular θ-dependent part of the general solution too. Whilst some
-symmetrized H
φ
Hamiltonians are considered, a recipe to keep the regular magnetic quantum number m, as defined in the regular traditional Hermitian settings, is suggested. Hamiltonians possess properties similar to the
-symmetric ones (here the non-Hermitian
-symmetric Hamiltonians) are nicknamed as pseudo-
-symmetric. 相似文献
8.
M. -G. Porquet A. Astier Ts. Venkova A. Prévost I. Deloncle F. Azaiez A. Buta D. Curien O. Dorvaux G. Duchêne B. J. P. Gall F. Khalfallah I. Piqueras M. Rousseau M. Meyer N. Redon O. Stézowski R. Lucas A. Bogachev 《The European Physical Journal A - Hadrons and Nuclei》2009,39(3):295-306
The 81, 82, 83, 85Se nuclei have been produced as fission fragments in the fusion reaction 18O + 208Pb at 85MeV bombarding energy and studied with the Euroball IV array. Their high-spin level schemes have been built from the
triple -ray coincidence data and - angular correlations have been analyzed in order to assign spin and parity values to many observed states. The lowest-spin
states of the two-neutron and three-neutron configurations are strongly mixed with two-proton excitations among the fp orbits. On the other hand, the highest-spin states of these neutron configurations are found to remain almost pure. Neutron
excitation across the N = 50 gap is observed both in 83Se49 and in 85Se51 . 相似文献
9.
R. Kumar Kuljeet Singh D. Mehta Nirmal Singh S. S. Malik E. S. Paul A. Görgen S. Chmel R. P. Singh S. Muralithar 《The European Physical Journal A - Hadrons and Nuclei》2005,24(1):13-22
The collective structures of 131Cs have been investigated by in-beam -ray spectroscopic techniques following the 124Sn (^11B , 4n) reaction at a beam energy Elab = 57MeV. The previously established rotational bands, built on g7/2, d5/2 and the unique-parity h11/2 orbitals, have been extended and evolve into new bands involving rotationally aligned (h11/2)2 and (h11/2)2 quasiparticles. In addition, a new multiquasiparticle band based on the g7/2 g7/2 h11/2 configuration has also been observed. Theoretical interpretations for the assigned configurations are discussed in the framework of Total Routhian Surface (TRS) and Tilted Axis Cranking (TAC) model calculations. TAC model calculations predict a decrease in the B(M1) values with increasing rotational frequency for the g7/2/d5/2 (h11/2)2 and h11/2 (h11/2)2 bands, thus indicating a magnetic rotation character for these bands. 相似文献
10.
Excited states in 191Pt have been populated using the reaction 186W + 11B at 85MeV beam energy. Gamma-ray coincidences were measured using the EUROGAM-II spectrometer array. The level scheme has been extended considerably. Evidence for favoured structures of highly triaxial shape with -90° coexisting with oblate structures has been obtained by comparison with total Routhian surface and cranked shell model calculations. The presence of proton excitations in both positive- and negative-parity states has been confirmed. 相似文献
11.
T. Grahn A. Dewald P. T. Greenlees U. Jakobsson J. Jolie P. Jones R. Julin S. Juutinen S. Ketelhut T. Kr?ll R. Krücken M. Leino P. Maierbeck B. Melon M. Nyman R. D. Page P. Peura Th. Pissulla P. Rahkila J. Sarén C. Scholey J. Sorri J. Uusitalo 《The European Physical Journal A - Hadrons and Nuclei》2009,39(3):291-294
The lifetime of the 17/2+ yrast state in 195Po has been measured using the recoil distance Doppler-shift technique to be = 43(11) ps. The lifetime was extracted from the singles -ray spectra obtained by using the recoil-decay tagging method. The present work provides more information of the coupling
schemes, shapes and configuration mixing in neutron-deficient odd-mass Po nuclei. 相似文献
12.
L. Gaudefroy O. Sorlin C. Donzaud 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 I. Matea J. Mrasek F. Nowacki F. de Oliveira Santos Yu. -E. Penionzhkevich B. Pfeiffer F. Pougheon M. G. Saint-Laurent M. Stanoiu 《The European Physical Journal A - Hadrons and Nuclei》2005,23(1):41-48
The neutron-rich nuclei 2157, 58Sc, 2258-60Ti, 2360-63V, 2462-66Cr have been produced at Ganil via interactions of a 61.8A MeV 76Ge beam with a 58Ni target. Beta-decay studies have been performed using combined - and -ray spectroscopy. Half-lives have been determined and -decay schemes are proposed for 58Ti, 61V and 62Cr. From these studies, new hints for the existence of -decaying isomers in 60V and in 62Mn are provided. These results are compared to shell model calculations. The role of the f7/2- f5/2 proton-neutron interaction is examined through its influence on the lifetime values. 相似文献
13.
We find that the experimental data of the -decay half-lives for 627 nuclei are in good agreement with Benford’s law, which states that the frequency of the appearance
of each figure, 1-9, as the first significant digit, follows a logarithmic distribution favoring the smallest value. In order
to generalize the applicability of Benford’s law, we systematically investigate the data of the total half-lives for 3177
nuclides in their ground and isomeric states, where the half-lives of many nuclei are determined by -decay and spontaneous fission. We find that they are also in excellent agreement with Benford’s law, although they are determined
by different interactions such as strong, weak and electromagnetic interactions. The possible physics behind them is discussed.
Moreover, Benford’s law can be used to test theoretical models or methods. 相似文献
14.
R. Alkofer C. S. Fischer R. Williams 《The European Physical Journal A - Hadrons and Nuclei》2008,38(1):53-60
The U
A(1) problem of QCD is inevitably tied to the infrared behaviour of quarks and gluons with its most visible effect being the
-mass. A dimensional argument of Kogut and Susskind showed that the mixing of the pseudoscalar flavour-singlet mesons with
gluons can provide a screening of the Goldstone pole in this channel if the full quark-quark interaction is strongly infrared
singular as ∼ 1/k
4 . We investigate this idea using previously obtained results for the Landau gauge ghost and gluon propagator, together with
recent determinations for the singular behaviour of the quark-gluon vertex. We find that, even with an infrared vanishing
gluon propagator, the singular structure of the quark-gluon vertex for certain kinematics is apposite for yielding a non-zero
screening mass. 相似文献
15.
High-spin states of 136La have been investigated with the reaction 130Te( 11B, 5n) at a beam energy of 60 MeV. The level scheme with three collective bands has been updated with spin up to 20 . The observed h11/2 h11/2 band shows -instability with increasing spin according to the TRS calculations. The band crossing and the signature splitting and inversion have been discussed. Other two collective bands based on 12-and 16+ levels were proposed as oblate deformation with -60°. They most probably originate from four- and six-quasiparticle configurations, that is, h11/2 g7/2h11/22 and g7/2 g7/22d5/2h11/22 respectively. 相似文献
16.
Yu. B. Gurov M. N. Behr D. V. Aleshkin B. A. Chernyshev S. V. Lapushkin P. V. Morokhov V. A. Pechkurov N. O. Poroshin V. G. Sandukovsky M. V. Tel’kushev 《The European Physical Journal A - Hadrons and Nuclei》2005,24(2):231-236
The superheavy hydrogen isotopes 4H and 5H have been investigated in the stopped pion absorption on 9Be. Three states of 4H were proposed in the reaction channel 9Be( { - }, dt)X. Four states of 5H were proposed in the reaction channels 9Be({ - }, pt)X and 9Be({ - }, dt)X. The excited states of 5H can decay into free nucleons. 相似文献
17.
T. Fukuchi Y. Gono A. Odahara S. Tanaka M. Inoue Y. Wakabayashi T. Sasaki M. Kibe N. Hokoiwa T. Shinozuka M. Fujita A. Yamazaki T. Sonoda C. S. Lee Y. K. Kwon J. Y. Moon J. H. Lee 《The European Physical Journal A - Hadrons and Nuclei》2005,24(2):249-257
The high-spin states of 93Mo have been studied by a 82Se( 16O, 5n) 93Mo reaction at a beam energy of 100 MeV using techniques of in-beam -ray spectroscopy. Measurements of -t, --t coincidences, -ray angular distributions and -ray linear polarizations were performed. The high-spin isomer was found as a (39/2-) state at about 9.7 MeV. The near-yrast states in 93Mo were interpreted using the weak-coupling picture of a d5/2 neutron to a neutron magic core nucleus 92Mo. 相似文献
18.
We have quantized a flat cosmological model in the context of the metric models, using the causal Bohmian quantum theory. The equations are solved and then we have obtained how the quantum corrections
influence the classical equations. 相似文献
19.
J. Sauvage J. Genevey B. Roussière S. Franchoo A. N. Andreyev N. Barré J. -F. Clavelin H. De Witte D. V. Fedorov V. N. Fedoseyev L. M. Fraile X. Grave G. Huber M. Huyse H. B. Jeppesen U. K?ster P. Kunz S. R. Lesher B. A. Marsh I. Mukha J. Oms M. Seliverstov I. Stefanescu K. Van de Vel J. Van de Walle P. Van Duppen Yu. M. Volkov 《The European Physical Journal A - Hadrons and Nuclei》2009,39(1):33-48
The /EC decay of 189m, gPb has been studied at the ISOLDE facility using nuclear spectroscopy and in-source laser spectroscopy. A level scheme of
189Tl has been built from - coincidence relationships and information on the feeding of some excited levels of 189Tl provided by the hyperfine spectra obtained from laser ionization. The half-lives of both the 13/2+ and 3/2-
189Pb isomers have been estimated to be T
1/2 = 50±3 s and T
1/2 = 39±8 s, respectively. Calculations have been performed for different oblate and prolate nuclear deformations using an axial-rotor
coupled to one-quasiparticle model, a structure has been suggested for the low-lying levels of the 189Tl nucleus. 相似文献
20.
F. P. Heßberger S. Hofmann D. Ackermann S. Antalic B. Kindler I. Kojouharov P. Kuusiniemi M. Leino B. Lommel R. Mann K. Nishio A. G. Popeko B. Sulignano S. Saro B. Streicher M. Venhart A. V. Yeremin 《The European Physical Journal A - Hadrons and Nuclei》2006,29(2):165-173
The decay of 255No was investigated by means of α-γ spectroscopy. The isotope was produced in the reactions 208Pb(48Ca, n)255No,
, and $238U(22Ne, 5n)255No$. Levels of the daughter nucleus 251Fm were assigned by α-γ coincidence measurements and on the basis of systematics. Level energies were determined precisely
using measured γ-rays. The results are compared with the known level schemes of the lighter
isotones 247Cm and 249Cf as well as with data for 253No. 相似文献