Decay of the 55 min and 12 min Te isomers

Gamma rays emitted in the decay of the ¹³³Te isomers, 55.4 min ^133mTe and 12.5 min ^133gTe, have been observed with Ge(Li) detectors. Sources were prepared by separating Sb from fission products, allowing several minutes for decay of 2.7 min ¹³³Sb and then separating the Te daughter activities. A total of 29 γ-rays between 312 and 2541 keV were attributed to decay of ^133gTe and 30 from 74 to 2050 keV to that of ^133mTe. Gamma-gamma coincidences in the decay of ^133gTe were observed with a NaI(Tl)---Ge(Li) set-up. The decay scheme of ^133gTe was constructed, involving placement of 25 of the γ-rays emitted. The decay of ^133gTe populates levels in ¹³³I at 0, 312, 720, 787, 1313, 1333, 1374, 1565, 1718, 2137, 2194 and 2541 keV. The decay of ^133mTe is very complicated, and we have not attempted construction of a complete decay scheme for it; however, levels at 913 and 1561 keV in ¹³³I are definitely populated in ^133mTe decay. The value for Q_β of ¹³³Te was measured as 3.52±0.10 MeV. The low-lying levels of the odd-mass iodine isotopes vary smoothly through the series ¹²⁵I through ¹³³I. The levels of ¹³³I are fitted rather well by predictions based on quasi-particle-phonon coupling.     

Nuclear structure studies in the Te isotopes: The Te(d, p)Te reaction

The reaction ¹²⁵Te(d, p)¹²⁶Te has been studied at a bombarding energy of 7.5 MeV in order to get information about the ¹²⁶Te nuclear level scheme. Forty-two levels were observed below an excitation energy of 5.1 MeV. The angular distributions of 25 of the emitted proton groups were compared with DWBA calculations to determine the angular momentum of the captured neutrons. Contributions from more than one l_n value were observed for two of the transitions. Transition strengths were extracted and compared to pairing-theory calculations.     

Magnetic dipole moments near Sn: Measurement on isomeric 11/2 states in odd-A Te and Te by NMR/ON

On-line low temperature nuclear orientation (OLNO) experiments have been performed on the odd-A Te isotopes ¹³¹Te and ¹³³Te using the technique of nuclear magnetic resonance on oriented nuclei (NMR/ON). The magnetic moments of the isomeric 11/2⁻ states have been measured extending the known data on these states in the Te isotopes up to the neutron shell closure at N = 82. The contribution to the 11/2⁻ magnetic moment in ¹³³Te due to core polarisation is calculated using an RPA shell model as well as corrections to the magnetic dipole operator caused by mesonic exchange currents. The neutron number dependence of the magnetic moments of the 11/2⁻ isomers in heavy Te isotopes is discussed in terms of particle-core coupling model (PCM) calculations.     

On the static quadrupole moments of the 21 states in Te and Te

The reorientation effect in Coulomb excitation was used to measure the static quadrupole moments of the first 2⁺ states in ¹²⁶Te and ¹²⁸Te. The particle-γ coincidence technique using a large NaI(Tl) crystal was employed to measure relative excitation probabilities at backward and forward projectile scattering angles. The Winther-de Boer multiple Coulomb excitation program was used to analyze the data. The influence of the deorientation effect was also determined. For positive interference via the second 2⁺ state the extracted quadrupole moments of the first 2⁺ states are; −0.20±0.09 b and -0.24±0.08 b for ¹²⁶Te and ¹²⁸Te respectively. The quadrupole moments of the first 2⁺ states of^{122,124,126,128,130}Te determined by different techniques are in excellent agreement with one another. The values are compared with recent theoretical calculations.     

时间相关穆斯堡尔谱与GaAs的119mTe离子注入

本文提出并实现了一种新的穆斯堡尔谱——时间相关穆斯堡尔谱。这是利用两步衰变^119mTe→¹¹⁹Sb→¹¹⁹Sn而获得的。测量了110keV ^119mTe加10¹⁵稳定Te/cm²注入并经600℃退火的样品在不同测量时间内的穆斯堡尔谱,分析了各谱线随ξ的变化。这里ξ是我们定义的参量,它等于Φ_Te/Φ_总,由退火时刻t_{a关键词：}     

Improved isospin dependent quantum molecular dynamics model and its application to fusion reactions near Coulomb barrier

The isospin dependent quantum molecular dynamics model is developed by introducing switch function method which deals with correctly the surface interaction and shell effect in the process of projectile and target approaching. The fusion excitation functions for ⁴⁰Ca + ⁴⁰Ca, ⁴⁰Ca + ⁴⁸Ca and ⁴⁸Ca + ⁴⁸Ca at energies in the vicinity of the Coulomb barrier are studied. The experimental data of the fusion cross sections for these three systems can be regenerated very well. It is found that the fusion cross sections for neutron-rich system increase obviously. The static and dynamical Coulomb barriers are studied in order to clarify the phenomena. The neutron to proton ratio (N/Z ratio) at neck region is also studied, which apparently presents isospin effects of projectile-target combinations.     

Nuclear structure studies in the tellurium isotopes: the Te(d, p)Te reaction

The levels of ¹²⁷Te have been studied with the ¹²⁶Te(d, p)¹²⁷Te reaction at 7.5 MeV bombarding energy using the MIT multiple-gap broad-range magnetic spectrograph. A total number of 154 levels was observed below 5.7 MeV excitation energy. The angular distributions of 47 of the emitted proton groups were compared with DWBA stripping calculations to determine the orbital angular momentum of the captured neutrons. Transition strengths (2J+1)S_{ln, j} were extracted and compared to pairing-theory calculations. The total number of vacancies measured in the and states in the target is 6.0 , which is considerably lower than the expected value of 7.4 from pairing theory. It is suggested that this discrepancy results mainly from failure of the DWBA theory to predict the correct cross section for the l_n = 5 transition.     

Shape Coexistence and Band Termination in Doubly Magic Nucleus 40Ca

Shape coexistence and band structure near yrast line of the Z=N doubly magic nucleus ⁴⁰Ca have been investigated by the configuration-dependent cranked Nilsson-Strutinsky approach. The observed normal deformed and superdeformed bands are explained and the terminating states are confirmed by the calculations. The transition quadrupole moment Q_t of the calculated superdeformed band is in good agreement with the observed one at high spin. There is shape coexistence within the same configuration. Possible normal deformed and superdeformed bands with rotation around the intermediate axis in several interesting configurations of ⁴⁰Ca are discussed. Possible favored superdeformed band terminations in ³⁸Ca and ³⁸Ar are predicted. The experimental results in ³⁸Ar are discussed simply.     

Shell-model calculations with Woods-Saxon wave functions in O and Ca

Two-particle states of ¹⁸O and ⁴²Ca are calculated within the shell model. The nuclear cores are represented by Woods-Saxon potentials, and for the residual interaction, central forces of Yukawa and Gaussian types are used. The wave functions for the low-lying states except for the O₂⁺ and 2₂⁺ states in ⁴²Ca are obtained, and the calculated energy spectra are in good agreement with experiments. Also E2 transitions are calculated and compared with experimental results.     

Cranked Skyrme–Hartree–Fock calculation for superdeformed and hyperdeformed rotational bands in N=Z nuclei from S to Cr

With the use of the symmetry-unrestricted cranked Skyrme–Hartree–Fock method in the three-dimensional coordinate-mesh representation, we have carried out a systematic theoretical search for the superdeformed and hyperdeformed rotational bands in the mass A=30–50 region. Along the N=Z line, we have found superdeformed solutions in ³²S, ³⁶Ar, ⁴⁰Ca, ⁴⁴Ti, and hyperdeformed solutions in ³⁶Ar, ⁴⁰Ca, ⁴⁴Ti, ⁴⁸Cr. The superdeformed band in ⁴⁰Ca is found to be extremely soft against both the axially symmetric (Y₃₀) and asymmetric (Y₃₁) octupole deformations. An interesting role of symmetry breaking in the mean field is pointed out.     

The (He, t) reaction at intermediate energies : Spin-isospin multipole transitions

Data for the (³He, t) reaction at 900 MeV and 2 GeV on the targets ²⁶Mg, ⁴⁰Ca, ⁴⁸Ca, ⁵⁴Fe, ⁹⁰Zr and ²⁰⁸Pb are presented. A multipole decomposition for the data at 900 MeV has been made and the different distributions have been analysed. From the L = 0 cross section the Gamow-Teller strength distributions are extracted and compared with (p, n) data. The L = 1 and 2 distributions are analysed in a schematic model which describes the general systematics fairly well. The spectra at 2 GeV and Θ = 4° show for all targets a well-developed quasi-elastic peak. The A-dependence of the cross section is analysed in a simple model.     

Folding Model Analysis of Elastic Scattering of 11B from Light,Medium, and Heavy Nuclei

The elastic scattering angular distributions of ¹¹B projectile on light, medium, and heavy target nuclei including ⁷Li, ⁹Be, ¹²C, ¹⁶O, ^24,25,26Mg, ²⁷Al, ²⁸Si, ⁴⁰Ca, ⁵⁸Ni, ⁵⁹Co, ⁶⁰Ni, ¹⁹⁷Au, ²⁰⁸Pb, and ²⁰⁹Bi have been analyzed at various incident energies. The theoretical results have been obtained by using two different nuclear potentials within the framework of the optical model (OM). Firstly, the double folding potential for real part and the Wood-Saxon (WS) potential for imaginary part have been applied. Secondly, the calculations with double folding potential for both real and imaginary part have been performed and compared with the experimental data. It has been seen that the results are in very good agreement with the experimental data. Also, the volume integrals and cross-sections for each reaction have been obtained. Finally, a new and simple formula for the imaginary potential depth has been derived to clarify the nuclear interactions of ¹¹B nucleus at low energy reactions.     

Pair Excitations in Even-Even Nuclei

A charge exchange term is added to the n-p effective interaction in treating eveneven nuclei with shape coexistence. The energy spectra and some of the E2 transition rates are calculated for ^112,114Cd, ^114,116Sn and ^118,120Te nuclei. The inclusion of this new term helps to improve an agreement with experimental data.     

Equivalent bare optical potentials in heavy-ion inelastic scattering

The equivalent bare optical potentials have been calculated for the inelastic scattering of ¹⁶O and ¹³C by ⁴⁰Ca at 60 and 68 MeV, respectively. The potentials obtained are quite consistent with those found phenomenologically by coupled-channels calculations. The shape of the bare potential is interpreted by showing the significant contribution of the nuclear—Coulomb cross term.     

IS 40Ca A STABLE ISOTOPE?

It is shorn that the double magic nucleus ⁴⁰Ca is unstable with respect to the double K-electron capture ⁴⁰Ar. By using the shell model wave functions for both ⁴⁰Ca and ⁴⁰Ar, the lifetime of ⁴⁰Ca is estimated as 1.2×10³³yrs.     

20Mgβ衰变谱学与15O(α,γ)19Ne反应(英文)

15O（α,γ）19Ne（p,γ）20Na反应链是高温CNO循环向快速质子俘获过程突破的一条关键路径,相关的反应率输入量可通过20Mg的β衰变可布居19Ne共振态并测量其衰变性质来获得。通过高效率高精度地测量20Mg β衰变中产生的质子与γ射线得到了20Mg衰变的详细信息,并构建了完整的衰变纲图,还进行了19Ne 4 033 keV共振态衰变性质的探索,获得了该态在20Mg β衰变中被布居的分支比上限。通过比20Mg和20O镜像能级跃迁的结果确认了同位旋非对称性,为检验相关理论模型提供了精确的实验数据。对于突破路径中有重要影响的19Ne 4 033 keV共振态的性质,有待更高统计的实验进一步研究。The breakout from the hot CNO cycle to the rapid proton capture process can occur via the 15O(α,γ)19Ne(p,γ)20Na reaction sequence, and the β decay of 20Mg can be used as an alternative method to characterize some specific resonances, which will provide detailed nuclear structure input for reaction rate calculations. The reliable information on the decay properties and structure of 20Mg was obtained by measuring the emitted particles and γ-rays in the β decay with high efficiency and high resolution. Attempt was also made to search for the decay channels associated with the 4 033 keV resonance in 19Ne. To test fundamental symmetries, the transitions in the mirror decays of 20Mg and 20O were compared. The precise experimental data presented here would be important to constrain the theoretical calculations. It is desirable to clarify the astrophysically relevant problem by further experiments with improved statistics on the basis of the present work.