## 2004 Vol. 28, No. S1

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2004, 28(S1): 1-4.
Abstract:
The experimental study on β-delayed proton decays near the proton drip line published by our group over the last 8 years were reviewed and summarized briefly,including first observation of 9 precursors in the rare-earth region and new measurements of 5 nuclei in the mass-90 region near N=Z line with the aid of the “p-γ” coincidence in combination with a He-jet tape transport system.Systematically comparing the experimental data with the current nuclear-model predictions, following points were represented. (1) the experimental half-lives for 85Mo and 92Rh as well as the predicted “waiting point”nuclei 89Ru and 93Pd are 5—10 times longer than the macroscopic-microscopic model predictions given by Moller et al [At. Data Nucl Data Tables, 66, 131(1997)]. It considerably influences the prediction of mass abundances of the nuclides produced in rp-process. (2) The current-model predictions are not consistent with the experimental spin-parity assignments of the proton drip-line nuclei 142Ho and 128Pm. However, the nuclear potential energy surface (PES) calculated by using a Woods-Saxon-Strutinsky method reproduced the experimental results. (3) The Alice code overestimated the production reaction cross sections of the studied 9 rare-earth nuclei by one order of magnitude or two, while HIVAP code overestimated them by one order of magnitude approximately.
2004, 28(S1): 5-10.
Abstract:
Through 122Sn(16O,4n), 130Te(11B,5n)and 107Ag(19F,1p3n) heavy-ion nuclear reactions and in-beam γ-ray spectroscopy technique, high spin states of 134Ce, 136La and 122Cs have been studied. The previous level schemes have been extended. The observed results show that the collective band structures in these three nuclear were affected by the shape-driving effects. The shape coexistence with different γ deformations has been observed in 134Ce. In 136La, the πh11/2⊙νh11/2 band was updated and its character has been discussed while two oblate bands with γ≈－60° have been established. In 122Cs chiral doublet bands were proposed. The magnetic rotational bands reported in a recent paper in 134Ce were not confirmed by our experiment.
2004, 28(S1): 11-15.
Abstract:
We used the cranking shell model to investigate the high-spin motions and structures of atomic nuclei. We focus the collective rotations of the A～50, 80 and 110 nuclei. The A～50 calculations show complicated g spectroscopy, which can have significant vibration effects. The A≈80 N≈Z nuclei show rich shape coexistences with prolate and oblate rotational bands. The A≈110 nuclei near the r-process path can have well-deformed oblate shapes that become yrast and more stable with increasing rotational frequency. As another important investigation, we used the configuration-constrained adiabatic method to calculate the multi-quasiparticle high-K states in the A～130, 180 and superheavy regions. The calculations show significant shape polarizations due to quasi-particle excitations for soft nuclei, which should be considered in the investigations of high-K states. We predicted some important high-K isomers, e.g., the 8 isomers in the unstable nuclei of 140Dy and 188Pb, which have been confirmed in experiments. In superheavy nuclei, our calculations show systematic existence of high-K states. The high-K excitations can increase the productions of synthesis and the survival probabilities of superheavy nuclei.
2004, 28(S1): 16-20.
Abstract:
Hanbury Brown-Twiss (HBT) results of the nucleon-nucleon correlation function have been presented for the nuclear reactions with neutron-rich projectiles (Be isotopes) using an event-generator, the Isospin-Dependent Quantum Molecular Dynamics model. We explore that the relationship between the strength of the neutron-proton HBT at small relative momentum and the binding energy of the projectiles. Moreover, we reveal the relationship between the strength of the proton-halo neutron HBT and the single neutron separation energy. Results show that neutron-proton HBT results are sensitive to binding energy or separation energy. The dependences of Equation of State (EOS) and in-medium nucleon-nucleon cross section of the HBT results are also presented.
2004, 28(S1): 21-26.
Abstract:
In this article, we briefly review recent developments of the relativistic mean field (RMF) theory towards a better description of structure of exotic nuclei and its applications to the study of exotic nuclear phenomena such as neutron and proton halo, giant halo and deformed halo, super heavy nuclei, hyper nuclei and symmetries in atomic nuclei
2004, 28(S1): 27-30.
Abstract:
The high spin states of 90Nb and 91Nb have been populated via reaction 76Ge(19F,xn) at beam energy of 80MeV. The de-exciting γ-rays have been measured with in-beam γ-ray spectroscopy method. After γ-γ coincidence analysis, the new level scheme of 90Nb and 91Nb was established. Based on the semi-empirical shell model calculations, the configurations of the levels have been suggested, in addition, the spins and parities of the new levels have been assigned according to the experimental DCO values and to the systematic comparison with the neighboring nuclei.
2004, 28(S1): 31-33.
Abstract:
The high spin states of 156Tm were populated using fusion evaporation 142Nd(19F,5n)156Tm reaction at beam energy of 122.5MeV.The γ-γ coincidence and DCO ratios were measured with 13 HPGe-BGO detectors. A level scheme with 29 levels and 33 γ-transitions was proposed. About 18 levels and 20 γ-transitions were added to the previous work. The energy levels were extended is up to 34.
2004, 28(S1): 34-35.
Abstract:
The effect on the variation of the moment of inertia in band 171Yb[521]1/2 is investigated using the particle number conserving (PNC) method for treating the cranked shell model with monopole and Y20 quadrupole pairing interactions. The experimental moments of inertia of 171Yb[521]1/2 (signature α=±1/2) and the blocking effect of proton are reproduced well by the PNC calculation, in which no free parameter is involved.
2004, 28(S1): 36-39.
Abstract:
The microscopic mechanism of the identical bands in odd-odd nucleus 194Tl and its neighbor odd-A nuclei 193,195Tl are investigated using the particle-number conserving (PNC) method for treating the cranked shell model with monopole and quadrupole pairing interactions. It is found that the blocking effect of the high-j intruder orbital plays an important role in the variation of moments of inertia (J(1) and J(2)) with rotational frequency for the superdeformed bands and identical bands. The ω variation of the occupation probability of each cranked orbital and the contributions to moment of inertia from each cranked orbital are presented.
2004, 28(S1): 40-42.
Abstract:
Reflection asymmetric shell model is applied for the description of the low-energy level spectrum in odd-A 221,223Ra nuclei. The ground-state spin parity and the ground-state parity doublet bands are well reproduced by the present model. The presence of parity doublets suggests reflection-asymmetric (octupole deformed) shapes for nuclei 221Ra and 223Ra.
2004, 28(S1): 43-46.
Abstract:
High-spin Level structure of 146Tb has been studied via the 118Sn(32S,1p3n)146Tb reaction using techniques of in-beam γ-ray spectroscopy. Based on the experimental measured results, the level scheme of 146Tb has been revised significantly and extended up to an excitation energy of 8.39 MeV. The doubly odd nucleus 146Tb has one proton-particle and one neutron--hole with respect to the doubly closed nucleus 146Gd, and its low-lying states should be 2-qp states, and the high-lying states should be 4-qp states or the coupling of 2-qp state to the low-lying excited states in 146Gd core. The excitation of the fully-aligned 4-qp configurations can also be well reproduced using the empirical shell-model approaches.
2004, 28(S1): 47-49.
Abstract:
High-spin states in doubly odd 170Re have been populated and investigated using 142Nd(32S,1p3nγ)170Re reaction at 166MeV bombarding energy. One rotational band in 170Re has been identified for the first time in the present study. The band has been assigned to be built on the πh11/2⊙νi13/2 configuration according to their quasiparticle alignment, signature splitting, level spacing systematics, as well as the existing knowledge in neighboring nuclei. The result extends the high-spin studies of A=170 odd-odd nuclei to the currently lightest rhenium isotope.
2004, 28(S1): 50-52.
Abstract:
High-spin states in 145Tb have been populated using the 118Sn(32S, 1p4n) reaction at a beam energy of 165MeV. The level scheme of 145Tb has been established for the first time. The level scheme shows characteristics of spherical or slightly oblate nucleus. Based on the systematic trends of the level structure in the neighboring N=80 isotones, the level structure in 145Tb below 2MeV excitation is well explained by coupling an h11/2 valence proton to the even-even 144Gd core. Above 2MeV excitation, most of the yrast levels are interpreted with multi-quasiparticle shell-model configurations.
2004, 28(S1): 53-55.
Abstract:
186mTa and 186Ta have been produced by irradiation of natW with 14MeV neutrons. The unreported tantalum isomer 186mTa has been identified by means of measuring known $\upgamma$ rays from 186Ta β-decay. The half-life of 186mTa has been determined to be 1.5±0.1 min.
2004, 28(S1): 56-58.
Abstract:
Through measuring high-fold prompt γ-ray coincidence events following the spontaneous fission of 252Cf with the Gammasphere detector array, new level scheme in the very neutron-rich 108Ru nucleus has been established. The ground-state band,the one-phone γ-vibrational band and a two-quasi-particle band have been confirmed and expanded. Besides, a two-phonon γ-vibrational band has been identified. From cranked shell model calculations, 108Ru nucleus may have triaxial deformation with parameters β2～0.29, γ=－22° and the band crossing in the yrast band is due to the alignment of two h11/2 neutrons. The possible configurations for the two-quasiparticle collective band were also discussed.
2004, 28(S1): 59-61.
Abstract:
High-spin states in 179,183Au have been studied experimentally using the 149Sm(35Cl,5n)179Au and 159Tb(29Si,5n)183Au heavy-ion reactions, respectively. The 1/2[660](πi13/2) rotational band has been established for the fist time in 179Au. A rotational band proposed as the unfavored signature branch of the πi13/2 band has been newly observed in 183Au. Properties of the 1/2[660](πi13/2)band in odd-A Au nuclei are discussed with an emphasis on the evolution of deformation while changing the neutron number.
2004, 28(S1): 62-65.
Abstract:
In-beam γ-ray spectroscopy experiment for odd-odd nucleus 142 Pm has been performed via the 128Te(19F,5n)142Pm reaction. Detailed analysis of γ-γ coincidence relationships leads to a revised high-spin level scheme for 142Pm above the previously known 2 ms 8 isomer. The πh11/2νh11/2－1 multiplet and the (πg7/2－1νh11/2－1)_{9^-} state in this nucleus have been identified based on systematic of corresponding states in neighboring odd-odd nuclei. Configurations of several levels have been suggested from an empirical shell model approach. The 67-μs isomer is proposed to be a fully-aligned 4-hole state with predominantly the ((\pi g_{7/2}^{-1}d_{5/2}^{-2})_{15/2^+}\otimes \upnu h_{11/2}^{-1})_{13^-} configuration.
2004, 28(S1): 66-68.
Abstract:
Recently it was found that the nuclear symmetry energy can be directly associated with the mean level density and an iso-vector potential. In this paper, the nuclear symmetry energy is studied within the relativistic mean field (RMF) theory. The potential of the RMF theory can be separated into an isovector and isoscalar components. The nuclear binding energies in A=48 isobaric chain calculated from RMF theory with or without the isovector terms for effective interactions PK1, NLSH, NL3, and TM1 have been used to analyze the nuclear symmetry energy in detail, i.e., mean level spacing ε and the effective isovector potential strength κ.
2004, 28(S1): 69-71.
Abstract:
The beta-decay of 176Yb→176Lu is calculated in the frame of projected shell model (PSM). The results are compared with experimental data.
2004, 28(S1): 72-74.
Abstract:
The halo structure of 11Be is investigated using the deoformed Skyrme-Hartree-Fock model. With adiabatic-blocking method, the 1/2+ state is predicted to have very large deformation. Corresponding to the energy minimum, the density distribution agrees well with the experimental data. This supports the deformed halo structure of 11Be.
2004, 28(S1): 75-77.
Abstract:
Through measuring high-fold prompt γ-ray coincidence events of the spontaneous fission of 252Cf with the Gammasphere detector array, rotational bands in neutron-rich 98Sr nucleus have been investigated. A deformed K=3 band built on 1838 keV level has been confirmed and extended. Another deformed K=6 band based on 2535 keV level has been established. Both bands originate most probably from the ν9/2[404]⊙ν3/2[411]two-quasiparticle configuration with Ω= |Ω1－Ω2|和Ω= |Ω12|, respectively. Based on the delay-coincidence measurements, the half-lives for the K=3 and K=6 band head levels has bee obtained to be 13±3ns and 4.5±1.0ns, respectively.
2004, 28(S1): 78-80.
Abstract:
The low-energy and low-spin part of the 83Rb nucleus was investigated in radioactive decay of 83Sr. The decay scheme was established and for a number of levels spin-parity assignments are suggested on the basis of log ft values and γ-branching ratios. In order to discuss the band structures of this nucleus，the projected shell model is applied to the nucleus 83Rb. The results of theoretical calculations about the excited positive-parity yrast states and the negative-parity ground-tate band are compared with experimental data， and the best reproduction of the experiment has been given by this model. In addition，a band diagram calculated for the negative-parity g. s. band is also shown in order to extract physics out of the numerical results.
2004, 28(S1): 81-83.
Abstract:
The triaxial deformations of candidate nuclei of the chiral doublets bands in A～100 mass region are investigated in a microscopic and self-consistent triaxial relativistic mean field (RMF) approach. The convergence of results is examined. Based on the constraint RMF calculation with effective interaction PK1, the deformations of ground state in Rh, Ag and In isotopes have been obtained. Large triaxial deformation necessary for chiral doublets band is predicted in several nuclei.
2004, 28(S1): 84-86.
Abstract:
A Shell-model-Like Approach (SLAP) is suggested for the pairing correlations within the relativistic mean field (RMF) theory. With the TMA interaction, the ground state properties and low-lying excited states for Ne isotopes are obtained and compared with the data available and BCS approximation. With SLAP for pairing, the blocking effect of odd nucleon can be treated consistently.
2004, 28(S1): 87-89.
Abstract:
The typical spectra corresponding to the U(5), SO(6) and SU(3)-limiting cases in the interacting boson model are studied within the framework of nucleon-pair shell model truncated to SD-subspace. It is found that they can all be reproduced approximately in the SD-pair shell model.
2004, 28(S1): 90-92.
Abstract:
The principle of RFQ (Radiofrequency Quadrupole) cooler and buncher is briefly introduced and some results of simulation by using the SIMION code are given. Compared to the other similar devices around the world,the being designed RFQ cooler and buncher has the following characteristics: much larger characteristic radius, much higher kinetic energy to be allowed to inject in and much higher helium buffer gas, so the difficulties to be overcome are listed.
2004, 28(S1): 93-95.
Abstract:
The σR for 14,15C and // of 13,14C fragments from 15C, and 13C fragments from 14C breakup have been measured at 83A MeV. FWHMs of // have been determined to be 71±9MeV/c and 223±28MeV/c for 14C and 13C from 15C, and 195±21MeV/c for 13C from14C. The FWHM for 13C from 15C and 14C are consistent with Goldhaber model's prediction. While the FWHM of 14C fragments from 15C is much smaller. An anomalous enhancement from its neighbors has been observed in the measured σR of 15C. The experimental data are discussed in the framework of the Glauber model. The analysis of both // and σR data indicate a dominant s-wave component in the ground state of 15C.
2004, 28(S1): 96-98.
Abstract:
An updated nuclear structure database was compiled and recommended by using recent evaluated experimental data and model calculated data. This database consists of the following three parts: the stable isotope abundances and atomic masses, the properties of the nuclear ground state and separated levels, the deformations，radii and other properties.
2004, 28(S1): 99-101.
Abstract:
The onset of the most powerful neutrino emission candidate in the cooling of neutron stars, direct URCA process, requires a high threshold proton fraction. The proton fraction in neutron stars relies on the isospin dependent part of nuclear force, which can be constrained by the measurement of the neutron skin thickness in heavy nuclei such as 208Pb. Adding new isospin dependent correction terms to the effective interactions PK1, NL3, S271 and Z271, the correlation between the proton fraction and neutron skin thickness in 208Pb is studied. For a neutron star with fixed mass, the central proton fraction increases with increasing predicted values of neutron skin thickness in 208Pb.
2004, 28(S1): 102-104.
Abstract:
A method of experimental determination of the sensitive volume(Sv)thickness d of micro-electronic devices is presented. It is based upon the deconvolution of the functions of heavy ion upset cross sections versus the range of the incidentions σseu(r), measured by varying the ion energy, and LET(r). The measured σseu(LET) and d can be used for accurate prediction of the rate of Single Event Effects (SEE) in space.
2004, 28(S1): 105-107.
Abstract:
The eigen values of the linear equations near the reference solutions of Hamiltonian-canonical equation are given by autonomy the time factor. It is demonstrated that the periodic time factor in octupole potential provides the particle to have more opportunity to encounter the negative curvature of the potential surface. Therefore the particle will be easier to get chaos, according to the discrimination of the motions for regulation and chaos.
2004, 28(S1): 108-112.
Abstract:
We study the ground state properties of even Dy isotopes, from the proton drip line to the neutron drip line, in the Relativistic Continuum Hartree-Bogoliubov theory with the NL-SH parameters. Firstly, our results show that theoretical binding energies and nuclear root mean square radii are in good agreement with the available experimental data. Secondly, we draw the following conclusions by investigating the calculated results: 1. within the neutron shell on N=82—126, there is an obvious sub-shell between the ranges of N=84—92 and N=94—126; 2. the predicted neutron drip line nucleus is $^{250}_{66}\rm Dy_{184}$; 3. characteristics of halos and giant halos appears in $_{\hspace{5.8ex}66}^{\text{240—250}}\rm Dy_{\text{174—184}}$ nuclei, among which there my be the giant halos.
2004, 28(S1): 113-115.
Abstract:
We study the roper N*(1440) excitation in the p(α,α′)πN reaction and reproduce the peak position of N*(1440) resonance in the target by using Monte Carlo simulation approach. Given a definite beam energy we could simulate the momentum distributions and angular distributions of final particles. One can observe the N*(1440) resonance peak obviously in the invariant mass spectrum, also, the event distribution is dense at 2100MeV2 of πN system energy square in Dalitz plots. But there are no such phenomenon in other composed systems. All of those things indicate that N*(1440) is produced.
2004, 28(S1): 116-118.
Abstract:
The E-Gamma Over Spin (E-GOS) analysis method is applied to study the shape evolution of yrast-bands in A～130 nuclei. It is found that these nuclei in A～130 region are in the transition from U(5) to SU(3) dynamical symmetry. 124—130Ba isotopes are to close O(6) dynamical symmetry.
2004, 28(S1): 119-122.
Abstract:
Spectra and E2 transition for the even-even 164—182Hf isotopes are studied in the framework of the interacting boson model. A schematic Hamiltonian can be used to describe their spectra and E2 transition. The results show that 164—182Hf are in the transition from the vibrational limit to rotational limit.
IF: 5.861

Monthly founded in 1977

ISSN 1674-1137 CN 11-5641/O4

Original research articles, Ietters and reviews Covering theory and experiments in the fieids of

• Particle physics
• Nuclear physics
• Particle and nuclear astrophysics
• Cosmology
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