Investigation of the HFS in the 4d 5p zP3,4 states of Mo and Mo by levelcrossing spectroscopy

The hyperfine structures of the z⁷P₃ and z⁷P₄ states of ⁹⁵Mo and ⁹⁷Mo have been investigated by levelcrossing spectroscopy. A fit of the experimental signal curves yields the magnetic and electric hfs coupling constants: ⁹⁵Mo z⁷P₃ |A| = 86.19(10) MHz, |B|=5.2(30) MHz, A/B0⁹⁵Mo z⁷P₄ |A|=64.05(30) MHz, |B|=4.3(30) MHz, A/B<0; ⁹⁷Mo z⁷P₃|A|= 88.0(1) MHz, |B|=60.0(20) MHz, A/B<0; ⁹⁷Mo z⁷P₄ |A|=65.4(3) MHz, |B|=50.0(50) MHz, A/B0. For the ratio of the electric quadrupole moments we fine ⁹⁷Q/⁹⁵ Q= -11.5(70).     

The (p, t) and (p, τ) reactions on O at 39.8 MeV

Differential cross sections have been measured at forward angles for (p, t) and (p, τ) transitions from ¹⁷O to the ⁻ ground states and lowest-energy ⁻ states in the ¹⁵O and ¹⁵N mirror nuclei. The data are compared with DWBA calculations using simple single-particle and single-hole wave functions. When the (p, t) and (p, τ) transitions are considered separately, the calculated and experimental ratios of the ⁻ integrated cross sections to the ⁻ integrated cross sections agree to within 30 %; however, the ratios of (p, τ) cross sections to the mirror state (p, t) cross sections are calculated to be about twice as large as actually measured. This experimentally observed reduction of the (p, τ) cross section relative to the (p, t) cross section can possibly be attributed to interference between the S = 0 and S = 1 components of the (p, τ) transitions.     

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.     

Pion-transfer (n, d) and (d, He) reactions leading to deeply bound pionic atoms

Theoretical studies are given on the (n, d) and (d, ³He) reactions leading to deeply bound pionic atoms in heavy nuclei of configuration [(nl)_π·j_n⁻¹]J. The cross sections for various pionic and neutron-hole configurations in the case of a ²⁰⁸Pb target are calculated at incident energies 300–1000 MeV/u by using the effective number approach and the eikonal approximation for distortion. The effective number with a pion in the 1s or 2p state and a neutron hole in the orbit peaks around the same incident energy (T_n = 600 MeV) as the elementary cross section n+n→d+π⁻, where the momentum transfer matches the angular-momentum transfer of L = 5–7. The DWIA cross section for (n,d) producing a pion in the 1s or 2p orbit at T_n = 600 MeV is found to be around 42 or 75 μb/sr, respectively. At T_n = 350 MeV, where the momentum transfer is small, quasi-substitutional states of configurations and are preferentially populated with (n, d) cross sections of 95 and 190 μb/sr, respectively. The (d, ³He) cross sections are estimated to be an order of magnitude smaller than the (n, d) cross sections. Thus, the (n, d) and (d, ³He) reactions are found to be suited for the production of deeply bound pionic atoms.     

Studies on the Ne(p, d)Ne and Ne(d, p)Ne reactions

Angular distribution measurements have been performed on the ²¹Ne(p, d)²⁰Ne and ²¹Ne(d, p)²²Ne reactions at E_p = 20 MeV and E_d = 10.2 MeV, respectively. In the ²¹Ne(p, d) ²⁰Ne reaction, the prolific formation of the J^π = 2⁺, 1.63 MeV state was characterized by l_n = 2 pickup, and the distribution associated with the 4⁴, 4.25 MeV state was suggestive of a weak l_n = 2 pickup. All of the observed l_n = 1 pickup strength is associated with formation of the 2⁻, 4.97 MeV ²⁰Ne level. The ²¹Ne(d, p)²²Ne results indicate that l_n = 2 transfer is involved in the formation of the 1.28, 3.36, 5.52, 5.63 and 6.65 MeV ²²Ne states. The angular distribution observed for the 2⁺, 4.46 MeV state and also the unresolved 5.33, 5.36 MeV composite of states required both l_n = 0 and l_n = 2 components in the associated distorted-wave Born approximation fits. The spectroscopic factors extracted from the present results are compared with those predicted by the Nilsson model without mixing: Applications of the angular momentum projection rule to the ²¹Ne(d, p)²²Ne reaction are considered.     

Spin-dependent reaction mechanism in Ti(d, p)Ti from proton-γ correlation

The γ-decays of the states in ⁴⁷Ti at 157 keV and 1547 keV have been studied following the ⁴⁶Ti(d, p)⁴⁷Ti reaction at 5.0 MeV incident energy. Protons were detected at 0° with a semiconductor detector. The angular correlations of the γ-rays with the reaction protons were measured. The E2/M1 mixing ratios of the γ-decays and the population ratios of the to the substates were deduced. From the non-zero population of the substate it was concluded that a spin-flip mechanism exists in the ⁴⁶Ti(d, p)⁴⁷Ti stripping reaction.     

Vector analysing power of the pick-up reaction C(d, t)C

The vector analysing power has been measured for the reaction ¹³C(d, t)¹²C initiated by 12.1 MeV polarized douterons and proceeding to the ground and 4.43 MeV states of ¹²C. Large analysing powers were observed especially for the ground state reaction. The results have been compared with the predictions of the distorted waves Born approximation and with data for the ¹²C(d, p)¹³C reaction     

The Mo(p, n)Tc reaction cross section and its use as a normalization for shuttle-system measurements

The ¹⁰⁰Mo(p, n)¹⁰⁰Tc reaction cross section was determined from 2 to 11 MeV (c.m.), by counting the delayed γ-rays from the ¹⁰⁰Tc decays (half-life = 15.8 s). These yields were measured with Ge(Li) and NaI(Tl) detectors and thick natural Mo targets. The use of this reaction as a normalizing reaction for cross-section measurements with a rapid target-transfer system is discussed. This technique was applied to the measurement of the astrophysically interesting ²³Na(p, n)²³Mg cross section (²³Mg HALF-LIFE = 11.57s). The results agree well with an independent ²³Na(p, n)²³Mg cross-section measurement.     

Electron screening effect in the reactions He(d, p)He and d(He, p)He

The cross section of the reactions ³He(d, p)⁴He and d(³He, p)⁴He has been measured at the center-of-mass energies E=5 to 60 keV and 10 to 40 keV, respectively. The experiments were performed to determine the magnitude of the electron screening effect leading to the respective electron-screening potential energy U_e=219±7 and 109±9 eV, which are both significantly higher than the respective values from atomic physics models, U_e=120 and 65 eV.     

Direct reactions to many-channel, many-level final states : (II). (d, p)n and (He, d)p

In an earlier paper, the cross section for a direct reaction to a generalised positive-energy final state, described by an R-matrix wave function, was derived. Here a distinction is emphasised between two classes of such a reaction, depending on whether it can or cannot decay back to the target state. A major contribution in the latter case can be via direct break-up. This is computed for the reaction ⁷Li(³He, d)⁸Be(p)⁷Li, treated by a stripping mechanism. The dependence of the cross section on the final-state (⁸Be) channel energy is discussed. The present work uses shell-model wave functions for R-matrix basis states, and this is shown to be appropriate and useful for direct reactions.     

A study of the Ca(d, p)Ca reaction (I). The single-particle states

The reaction ⁴⁰Ca(d, p)⁴¹Ca has been studied with a resolution 30 keV. Excitation functions for the first three strong states have been measured in the energy interval 9.80 to 12.12 MeV. Cross section fluctuations are found to be entirely within statistics, i.e. < 5 %, and it is concluded that σ_CN(θ)/(2J_f+1) < 5 μb/sr. Differential cross sections have been measured for elastic scattering, and the (d, p) transitions to the ground state and the strong single-particle states at E^* = 1.949, 2.471, 3.623 and 3.954 MeV at E_d = 12.00 MeV and, over a limited angular range, at E_d = 11.00 MeV. The angular distributions have been analysed by the DWBA method and spectroscopic factors have been determined. It is suggested that the 3.623 MeV state may be the third state predicted by Gerace and Green rather than as assigned by earlier studies.     

Nucleon-nucleon final-state interactions in the reactions He(p, d)2p, He(p, t)2p and He(p, He)pn

The energy spectra of deuterons, tritons and ³He particles from the reactions ³He(p, d)2p, ⁴He(p, t)2p and ⁴He(p, ³He)pn have been measured at angles between 6° and 60° lab. The ³He(p, d)2p reaction was studied at both 30.5 and 49.5 MeV incident proton energies, while the other two reactions were studied at 49.5 MeV only. The energy spectra are compared with calculations based on the Watson-Migdal model of final-state interactions.     

关于93Mo中21/2+晕阱的来源(英文)

本研究通过壳模型计算研究了N=51的同中子素91Zr、93Mo和95Ru中高自旋晕态21/2+的同核异能态现象。计算发现,低角动量的p_1/2轨道上的质子是仅在93Mo中存在21/2+晕阱的主要原因。同时,本工作还研究了N=52的同中子素92Zr、94Mo和96Ru中10₁+-12₁+能级结构的系统性,发现94Mo中的10₁+-12₁+能级间隙相对最小,考虑到与93Mo的17/2₁+-21/2₁+能级相似的组态,这一结果为93Mo中出现21/2+晕阱提供了补充性的论证。Isomerism of the high-spin yrast 21/2+ states of the N=51 isotones 91Zr, 93Mo and 95Ru has been investigated using the shell model calculations. It is found that the low-j πp_1/2 is responsible for the only yrast trap in 93Mo. In addition, the relatively smaller 10₁+-12₁+ level spacing in 94Mo has been found by investigating the systematics of the 10₁+-12₁+ level structures in the N=52 isotones 92Zr, 94Mo and 96Ru. This result provides a supplementary argument to the origin of the 21/2+ yrast trap in 93Mo from the viewpoint of the similarity between the configurations of 10₁+-12₁+ states in 94Mo and those of 17/2₁+-21/2₁+ states in 93Mo.     

A study of the S levels and the analogue levels of P by the P(He, d)S reaction

The ³¹P(³He, d)³²S reaction has been studied with high resolution at 12 MeV bombarding energy. A detailed level scheme for ³²S has been determined up to an excitation energy of 9.5 MeV revealing several previously unobserved states. The l_p values and absolute spectroscopic factors extracted from a DWBA analysis of the experimental deuteron angular distributions have provided information on the wave functions for the T = 0 states as well as for the T = 1 isobaric analogue states of ³²P. A comparison between the present data and those of previous experiments is made, and the results are discussed in terms of existing theoretical work in this mass region. Information on Coulomb displacement and symmetry energies is also extracted.     

A unified description of shape coexistence and mixed-symmetry states in ~(98)Mo using IBM-2

Level structure and electromagnetic transitions in ~(98)Mo have been investigated on the basis of the proton-neutron interacting boson model(IBM-2) by considering the energy difference between neutron boson ε_ν and proton boson ε_π. The results are compared with the recent experimental data and it is observed that they are in good agreement. In particular, the strongest M1 transition from 2_5~+ state to 2_2~+ can be well reproduced, from which one can determine the 2_5~+ as an mixed-symmetry(MS) state. We have calculated the electric monopole strength ρ~2(E0,0_2~+→0_1~+), and our result agrees with the experimental one. The calculation indicates that shape coexistence and MS states are simultaneously well described using IBM-2.     

Nuclear properties of Z=114 isotopes and shell structure of ~(298)114

The two-neutron separation energies(S_(2n)) and α-decay energies(Q_α) of the Z=114 isotopes are calculated by the deformed Skyrme-Hartree-Fock-Bogoliubov(SHFB) approach with the SLy5,T22,T32 and T43 interactions.It is found that the tensor force effect on the bulk properties is weak and the shell closure at N=184 is seen evidently with these interactions by analyzing the S_(2n) and Q_α evolutions with neutron number N.Meanwhile,the single-particle energy spectra of ~(298)114 are studied using the spherical SHFB approach with these interactions to furthermore examine the shell structure of the magic nucleus ~(298)114.It is shown that the shell structure is almost not changed by the inclusion of the tensor force in the Skyrme interactions.Finally,by examining the energy splitting of the three pairs of pseudospin partners for the protons and neutrons of ~(298)114,it is concluded that the pseudospin symmetry of the neutron states is preserved better than that of the proton states and not all of the pseudospin symmetries of the proton and neutron states are influenced by the tensor force.     

FPT-CNDO/INDO化学屏蔽常数计算方法及其在Mo和Co化合物中的应用

Semi -empirical molecular orbital methods within the framework of the finite perturbation theory , the FPT-CNDO/INDO methods , which consist of the FPT-CNDO/2 and FPT-INDO methods, are set up for the study of chemical shielding in transition metal compounds, and a corresponding computational program is developed on VAX 11/785 computer to establish a theoretical study of the transition metal chemical shielding by quantum chemistry methods. Application of the methods has been carried out in the calculation of 95Mo chemical shielding constants of mononuclear precursors [MoOnS4-n]2-(n=0-4). With the standard CNDO/INDO parameters a linear regression was obtained between the calculated results and the corresponding experimental data:δcal=(0.8345 δexp-43.83)ppm, with a correlation coefficient of 0.999. Investigation on the calculated electronic configuration confirms that in [MoOnS4_n]2- (n=0-4)95Mo chemical shifts are dominated by the d-orbital paramagnetic contribution arising from the d-d transition. Appl     

Investigation of the S(d, p)S reaction at Ed = 10 MeV

Angular distributions of proton groups, corresponding to fifteen levels observed in the reaction ³⁴S(d, p)³⁵S at E_d = 10 MeV have been measured with a split-pole spectrograph equipped with position-sensitive detectors. For the levels at E_x = 0, 1.58, 1.99, 2.34, 2.73, 3.68, 3.80 and 4.20 MeV, l_n = 2, 0, 3, 1, (2, 3), (1), 1 and 1, respectively, has been found from a DWBA analysis. Experimental spectroscopic factors and those following from many-particle shell-model calculations for the lowest four states are in satisfactory agreement. The ground state Q-value has been measured as Q = 4757 ± 5 keV.