共查询到20条相似文献,搜索用时 281 毫秒
1.
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
2.
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
3.
T. Shizuma T. Ishii H. Makii T. Hayakawa M. Matsuda 《The European Physical Journal A - Hadrons and Nuclei》2009,39(3):263-266
Excited states in neutron-rich 183Ta have been studied using a two-neutron transfer reaction of 181Ta(18O,16O) . In-beam -rays were measured in coincidence with scattered ions detected by a high-resolution
E -E Si telescope for reaction channel selection. Previously known 1-quasiparticle bands are extended to higher spins, and several
levels including a T
1/2 = 0.9(3) μs 3-quasiparticle isomer are identified. 相似文献
4.
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
5.
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
6.
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
7.
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
8.
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
9.
Redamy Perez-Ramos 《The European Physical Journal C - Particles and Fields》2009,62(3):541-545
The energy evolution of average multiplicities and multiplicity fluctuations in jets produced in heavy-ion collisions is investigated
from a toy QCD-inspired model. In this model, we use modified splitting functions accounting for medium-enhanced radiation
of gluons by a fast parton which propagates through the quark–gluon plasma. The leading contribution of the standard production
of soft hadrons is enhanced by a factor
while next-to-leading order (NLO) corrections are suppressed by
, where the parameter N
s
>1 accounts for the induced soft gluons in the medium. Our results for such global observables are cross-checked and compared
with their limits in the vacuum. 相似文献
10.
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
11.
A. Caciolli L. Agostino D. Bemmerer R. Bonetti C. Broggini F. Confortola P. Corvisiero H. Costantini Z. Elekes A. Formicola Zs. Fül?p G. Gervino A. Guglielmetti C. Gustavino Gy. Gyürky G. Imbriani M. Junker M. Laubenstein A. Lemut B. Limata M. Marta C. Mazzocchi R. Menegazzo P. Prati V. Roca C. Rolfs C. Rossi Alvarez E. Somorjai O. Straniero F. Strieder F. Terrasi H. P. Trautvetter 《The European Physical Journal A - Hadrons and Nuclei》2009,39(2):179-186
Ultra-sensitive in-beam -ray spectroscopy studies for nuclear astrophysics are performed at the LUNA (Laboratory for Underground Nuclear Astrophysics)
400 kV accelerator, deep underground in Italy’s Gran Sasso laboratory. By virtue of a specially constructed passive shield,
the laboratory -ray background for < 3 MeV at LUNA has been reduced to levels comparable to those experienced in dedicated offline underground -counting setups. The -ray background induced by an incident -beam has been studied. The data are used to evaluate the feasibility of sensitive in-beam experiments at LUNA and, by extension,
at similar proposed facilities. 相似文献
12.
Beatrice Malgesini Eduard Felder Nicola Mongelli Gianluca Papeo 《Molecular diversity》2009,13(1):53-56
Polyfluorinated N-α-Fmoc--Boc-l-lysine represents the best-in-class among a set of polyfluorinated amino acids (PFAs) which are useful tools for 19F NMR-Based Screening. In this communication, optimized reaction conditions that allowed for the multi-gram preparation of
this unnatural amino acid are reported. 相似文献
13.
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
14.
The present work is to construct the potential energy function of isotopic molecules. The so-called molecular potential energy
function is the electronic energy function under Born-Oppenheimer approximation, in which the nuclear motions (translational,
rotational and vibration motions) are not included, therefore, its nuclear vibration motion and isotopic effect need to be
considered. Based on group theory and atomic and molecular reactive statics (AMRS), the reasonable dissociation limits of
D2O are determined, its equilibrium geometry and dissociation energy are calculated by density-functional theory (DFT) B3lyp,
and then, using the many-body expansion method the potential energy function of D2O is obtained for the first time. The potential contours are drawn, in which it is found that the reactive channel D + OD→D2O has no threshold energy, so it is a free radical reaction. But the reactive channel O + DD→D2O has a saddle point. The study of collision for D2O is under way.
Supported by the National Natural Science Foundation of China (Grant No. NSAF10676022) 相似文献
15.
Oluseyi Latunde-Dada 《The European Physical Journal C - Particles and Fields》2008,58(4):543-554
We study the effects of gluon radiation in top-pair production and their decays for e
+
e
− annihilation at the ILC. To achieve this we apply the POWHEG method and interface our results to the Monte Carlo event generator
. We consider a centre-of-mass energy of
GeV and compare decay correlations and bottom-quark and -antiquark distributions before hadronisation. 相似文献
16.
We discuss the reaction π-e- → π-e-π0 with the purpose of obtaining information on the γπ → ππ anomalous amplitude
3π. We compare a full calculation at
(p6) in chiral perturbation theory and various phenomenological predictions with the existing data of Amendolia et al. By integrating our theory results using Monte Carlo techniques, we obtain σ = 2.05 nb at
(p6) and σ = 2.17 nb after including the dominant electromagnetic correction. Both results are in good agreement with the experimental cross-section of σ = (2.11±0.47) nb. On the basis of the ChPT results one would extract from the experimental cross-section as amplitudes
3π(0)extr = (9.9±1.1) GeV-3 and
3π(0)extr = (9.6±1.1) GeV-3, respectively, which have to be compared with the low-energy theorem
3π = e/(4π2Fπ3) = 9.72GeV-3. We emphasize the need for new data to allow for a comparison of experimental and theoretical distributions and to obtain
3π with smaller uncertainty. 相似文献
17.
K. Azizi R. Khosravi V. Bashiry 《The European Physical Journal C - Particles and Fields》2008,56(3):357-370
Taking into account the gluon correction contributions to the correlation function, the form factors relevant to the rare
decays are calculated in the framework of the three-point QCD sum rules, where X stands for axial vector particle, AV(D
s1), and vector particles, V(D
*,D
s
*). The total decay width as well as the branching ratio of these decays are evaluated using the q
2 dependent expressions of the form factors. A comparison of our results with the predictions of the relativistic constituent
quark model is presented. 相似文献
18.
Zhi-Gang Wang 《The European Physical Journal C - Particles and Fields》2009,61(2):321-329
We calculate the masses and the pole residues of the
heavy baryons Ω
c
0(css) and Ω
b
−(bss) with the QCD sum rules. The numerical values
GeV (or
GeV) and
GeV (or
GeV) are in good agreement with the experimental data. 相似文献
19.
Zhi-Qing Zhang Zhen-Jun Xiao 《The European Physical Journal C - Particles and Fields》2009,59(1):49-66
We calculate the important next-to-leading-order (NLO) contributions to the B→KK
* decays from the vertex corrections, the quark loops, and the magnetic penguins in the perturbative QCD (pQCD) factorization
approach. The pQCD predictions for the CP-averaged branching ratios are
,
,
and Br(B
0→K
+
K
*−+K
−
K
*+)≈1.3×10−7, which agree well with both the experimental upper limits and the predictions based on the QCD factorization approach. Furthermore,
the CP violating asymmetries of the considered decay modes are also evaluated. The NLO pQCD predictions for
and
decays are
and
. 相似文献
20.
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