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1.
With a 45 MeV deuteron beam the 94Mo(d, 6Li)90Zr and 92Zr(d, 6Li)88Sr reactions have been studied to search for α-vibration states in 90Zr and in 88Sr. No evidence is found for such a state in both nuclei with a strength > 5 % than that of the ground state. Strongly excited 0+ states in 88Sr and 90Zr are those also seen in two-nucleon stripping and pickup reactions. 相似文献
2.
A.S. Demyanova S.A. Fayans Yu.A. Glukhov A.A. Ogloblin S.B. Sakuta S.N. Ershov F.A. Gareev N.I. Pyatov 《Nuclear Physics A》1985,444(3):519-540
The energy spectra of 6He nuclei from the 90Zr(6Li, 6He) reaction at E6Li = 93 MeV have been measured over the angular range of 7 ° ? θlab ? 20 °. The theoretical DWBA analysis of these spectra and angular distributions was performed employing transition densities of bound and resonance states obtained on the basis of the theory of finite Fermi systems. It is shown that up to excitation energies of Ex ≈ 10 MeV in 90Nb a direct charge-exchange mechanism dominates in this reaction, while at higher Ex the contribution made by multistep processes increases significantly. It is also shown that the quasi-elastic cross section is determined by a sum of partial contributions of spin-isospin-flip transitions with multipolarities L=0 through L=6. 相似文献
3.
T. A. Khan W. D. Lauppe H. A. Selič H. Lawin G. Sadler M. Shaanan K. Sistemich 《Zeitschrift für Physik A Hadrons and Nuclei》1975,275(3):289-296
A windowless Si(Li) electron detector has been used in conjunction with the gas filled fission product separator JOSEF to study totally converted transitions in Zr and Mo isotopes. The existence of twoβ-decay modes in96Y,98Y and100Nb is confirmed. The half-lives of theβ-decaying levels feeding O 2 + states in96Zr and98Zr are 6.0 ± 0.4 sec and 0.60±0.05 sec respectively. A search for other first excited O 2 + states shows that no such states are apparent in100Zr and104Mo. 相似文献
4.
F. Schussler J.A. Pinston E. Monnand A. Moussa G. Jung E. Koglin B. Pfeiffer R.V.F. Janssens J. van Klinken 《Nuclear Physics A》1980,339(3):415-428
Using the on-line mass separator OSTIS for studies of short-lived fission products, we found two modes for the β-decay of 98Rb with respective half-lives of 96 and 114 ms. The latter decay populates a 0+ state in 98Sr at the unusually low energy of 215.5 keV, which is by far the lowest 0+ excited state observed in even-even nuclei. The half-lives of the 0+ and the 21+ states in 98Sr were found to be respectively 25 ns and 4 ns. The transition probabilities, the reduced E0 matrix element and the observed level structure suggest shape coexistence for 98Sr: the spheroidal 01+ ground state shows a rotational band with the 2+, 4+, (6+) levels, whereas the presumably spherical 02+ excited state may be connected with the 2+ level of a vibrational band. A simple model is proposed. 相似文献
5.
Angular correlation measurements of K- and L-conversion electrons following the decay 192Ir → 192Pt have been made using a spectrometer with Ge(Li) and Si (Li) detectors. Absolute and relative internal conversion coefficients of transitions in 192Pt were measured, using an ICC and prism β-spectrometers, to ≈ 2 % and values of δγ determined from the relative ICC. The experimental values measured in the study, A22(K296γ316) = 0.138 ± 0.010, A22(L296γ316) = 0.125 ± 0.013, αK(296) = 0.0711 ± 0.0011, K/LIII = 9.65 ± 0.13. With δγ = + 5.4 ± 0.2, were employed for determining the E0/E2 amplitude ratios of conversion transitions, q(E0/E2), and the penetration parameter λ of the Ml component for the 2+' → 2+ (296 keV) transition in 192Pt. The angular correlation measurements of L-conversion electrons enabled the elimination of one of two ranges of values of q and λ usually obtained. For the first time in our work, analysis of the eLγ angular correlation for the determination of the E0 component in the transition was carried out. As a result, q = +0.04 ± 0.05 with λ = ?4.5 ± 3.5 was obtained for the 296 keV transition. In this case, ρ(E0) = 0.004 ± 0.005 agrees with ρ(E0) = +0.006 determined theoretically by Kumar and Baranger for the 2+' → 2+ transition 相似文献
6.
R. Julin J. Kantele M. Luontama A. Passoja 《Zeitschrift für Physik A Hadrons and Nuclei》1981,303(2):147-150
Branching ratios ofE0 andE2 transitions depopulating the 0 2 + states of88, 92, 94Zr have been determined using conversion-electron and γ-ray spectroscopy. Two different lifetime-measurement methods were applied in the remeasurement of the half-lives of the 0 2 + states in92, 94Zr, yielding consistent results ofT 1/2(0 2 + ,92Zr)=85(15) ps andT 1/2(0 2 + ,94Zr)=280(40) ps. The monopole strengths extracted areρ 2(92Zr)=8.4(17) ×10?3 andρ 2(94Zr)=11.9(20)×10?3. The proton configurations of the 0 2 + states are discussed in view of these values and proton transfer data. 相似文献
7.
D.V. Aleksandrov Yu.A. Glukhov A.S. Demyanova A.A. Ogloblln S.B. Sakuta V.V. Sukharevsky S.V. Tolokonnikov S.A. Fayans F.A. Gareev S.N. Ershov I.N. Borzov J. Bang 《Nuclear Physics A》1985,436(2):338-364
The reaction 14C(6Li, 6He)14N was investigated with 93 MeV 6Li ions in an angular interval of 7–26°. Angular distributions were analysed for the four most intense groups of 6He nuclei, corresponding to transitions to the ground (11+) and the excited (12+, 21?, 41?) states of 14N. In the theoretical analysis a mechanism of the spin-isospin excitation was suggested in the DWBA frame with the finite range of interaction and recoil in the light system (6Li6He) taken into account. In the calculations both shell-model wave functions and transition densities obtained in the theory of finite Fermi systems (FFS) were used. From the comparison between theory and experiment the Landau-Migdal force constant g′ is estimated in order to obtain some information on the degree of nuclear proximity to the threshold of pion condensation. 相似文献
8.
A. Passoja R. Julin J. Kantele J. Kumpulainen M. Luontama W. Trzaska 《Nuclear Physics A》1985,438(2):413-428
The E0 and E2 transitions depopulating the excited 0+ states in 64,66,68Zn are investigated. Several methods of γ-ray, conversion-electron and internal-pair spectrometry are employed, including a new time measurement technique. A total of 5 E0 transitions are observed and the monopole strengths ρ2(0i+ → 0i+) for most of them are extracted. The results and the nature of the excited 0+ states are discussed in terms of several nuclear models. 相似文献
9.
A. Bäcklin N.G. Jonsson R. Julin J. Kantele M. Luontama A. Passoja T. Poikolainen 《Nuclear Physics A》1981,351(3):490-508
0+ states and their depopulating E0 and E2 transitions have been studied in 112–124Sn. Several methods of γ-ray and electron spectrometry have been employed, including special coincidence techniques for lifetime, conversion electron and double Coulomb excitation measurements. For 114–118Sn the E2 transition probabilities from the first excited 0+states (02+) are about 20 W.u., which is compatible with a vibrational two-phonon character. Also the E0 transition probabilities from these states are within a factor of two from the vibrational values. For the second excited 0+ states (03+) the corresponding E2 and E0 transition probabilities are considerably smaller. A total of 12 E0 transitions have been observed. The 03+ → 02+ transition is observed in 114–120Sn and has in 116Sn a reduced transition probability 1–2 orders of magnitude larger than those of the groundstate E0 transitions, which indicates that the 03+ and 02+ states are strong mixtures of components with different 〈r2〉. The 0+ states in 116Sn are discussed as possible rotational band heads associated with a deformation β2 ≈ 0.2. The Coulomb excitation cross section of the 02+ state is found to be sensitive to an interference term including matrix elements with the 22+ state. The relative sign of this term has been determined. 相似文献
10.
Simultaneous analysis of neutron and proton inelastic scattering to low-lying collective states in90, 92, 94Zr are used to derive an isospin decomposition of the corresponding transition matrix elements. The deduced (M n/Mp) ratios for the strongest transitions are in sharp disagreement with values derived from Coulomb-nuclear interference observed in 35.4 MeV inelastic α-scattering from even Zr isotopes. 相似文献
11.
Wolfgang Cassing 《Nuclear Physics A》1985,433(3):479-494
Nucleus-nucleus collisions with center-of-mass energies Ec.m. close to the Coulomb barrier are investigated within the framework of time-dependent two-center shell-model states. The influence of Landau-Zener transitions on the nucleus-nucleus potential is studied in detail as a function of Ec.m. Dynamical barrier shifts and barrier fluctuations are evaluated for central collisions of 90Zr + 90Zr, 92Zr + 92Zr, 96Zr + 96Zr and their effect on the fusion probability is discussed explicitly. While for 90Zr + 90Zr no modification of the barrier penetration is found a relative enhancement (reduction) of the fusion probability up to a factor of 4 is obtained for 92Zr + 92Zr and96Zr + 96Zr. 相似文献
12.
Lifetimes have been measured in 91Zr and 93Mo by the Doppler shift attenuation method through the 90Zr(13C, 12C)91Zr and the 92Mo(13C, 12C)93Mo reactions. Gamma rays were observed in coincidence with the back scattered particles and the reactions took place at sub-Coulomb energies. The lifetimes measured in 91Zr are τ(1205) = 250+90?70 fs, τ(1467) = 280+160?110 fs, τ(2042) < 30 fs, τ(2558) = 180+90?60 fs. The lifetimes measured in 93Mo are τ(1361) = 170+80?40 fs, τ(1494) = 60 ± 40 fs, τ(1697) = 440+230?130 fs, τ(2705)=160+80?60fs These results are compared with the expectations of the shell model and the transition is shown to be very enhanced. 相似文献
13.
A. Vitturi L. Ferreira P.D. Kunz H.M. Sofia P.F. Bortignon R.A. Broglia 《Nuclear Physics A》1980,340(1):183-204
The (6Li, d) and (d, 6Li) L = 0 transitions in the mass regions are analyzed utilizing microscopic form factors. The cross sections follow the pattern given by the two-proton and two-neutron transfer cross sections. 相似文献
14.
S. Gilad S. Cochavi M.A. Moinester J. Alster M. Buenerd P. Martin 《Nuclear Physics A》1974,233(1):81-90
The hole-hole structure of 94Y was studied via the reaction 96Zr(d, α)94Y and compared to the particle-hole structure of 90Y, which was populated by the reaction 92Zr(d, α)90Y. The deuteron beam energy was 28 MeV. Angular distributions of both reactions were obtained for the prominent lines. New states of 94Y were observed at 0.44, 1.17, 1.39, 1.53, 1.82, 1.90, 2.17, 2.33, 2.46 and 2.77 MeV. Our data are consistent with the previously reported 2? assignment of the ground state, and we suggest Jπ = 3? for the 0.44 MeV state, these being members of the doublet. The 1.17 state is suggested to be a member of the multiplet. The Q-value of the 96Zr(d, α)94Y reaction was measured to be 7.609 ± 0.020 MeV. The reaction 94Zr(d, α) was performed at two angles. Several new states of 92Y were observed at 0.31, 0.78, 1.03, 1.31, 1.49, 1.69 and 1.89 MeV. 相似文献
15.
The recently developed magnetic plus Si(Li)-Si(Li) sum-coincidence technique is employed to measure E0 internal-pair-formation (IPF) branching ratios of excited 0+ states in 58,60,62Ni. The values are obtained for a new 0+4 state in 60Ni at 3588.0 keV, for the 0+2 and 0+3 states at 2942.3 keV and 3530.9 keV in 58Ni, for the corresponding states at 2284.8 keV and 3318.3 keV in 60Ni, and for the 0+2 state in 62Ni at 2048.4 keV. The results are combined with the available lifetimes of these states to extract the monopole strengths ?2(0+i ? 0+1). The results and the nature of the 0+ states are discussed. 相似文献
16.
The reactions (α, 3nγ) and (α, α′nγ) on 88Sr, 90Zr and 92Mo were used to populate excited states in 89Zr, 91Mo and 93Ru. The de-excitation of these states was studied by in-beam γ-ray spectroscopy. The short-lived radioactivity of the 92Mo target was measured in order to study the decay of 93Ru. Many new levels were observed, particularly in 91Mo. They are interpreted as due to the coupling of a neutron hole with known excited states in 90Zr, 92Mo and 94Ru. 相似文献
17.
18.
Coupled-channels study of projectile and target excitation in the scattering of 6Li from 12C and 16O
J. Cook 《Nuclear Physics A》1985,445(2):350-366
Coupled-channels calculations are presented tor elastic and inelastic 6Li + 12C scattering at Ec.m. = 16 MeV and 20 MeV, and for 6Li + 16O at 18.7 MeV. Excitation of states within 6Li, 12C and 16O are treated with rotational, rotation-vibration and vibrational models only. The 3+6Li and 2+12C states are strongly coupled to the elastic scattering and reduce the strengths of both the real and imaginary potentials. The 3?16O state reduces only the strength of the imaginary potential. All other states are weakly coupled and have little effect on each other or the potential. The data are reasonably well described, with there being some preference for the 3? state in 12C to be K = 0. Excitation of the 02+ state in 12C requires a combination of β-vibration and monopole breathing-mode form factors. The deformation lengths found are in poor agreement with those deduced from electron or proton scattering. 相似文献
19.
The decays of 144Pr and 144Pm populate ten excited states in 144Nd. We have carried out detailed γγ angular correlation measurements in order to establish spin assignments for these levels. The measurements were performed with Ge(Li)-Ge(Li) and NaI(Tl)-Ge(Li) systems. Eleven sets of A22 and A44 values were obtained. The Jπ assignments for levels in 144Nd (level energies in keV) are as follows: g.s.,0+; 696, 2+; 1314, 4+ ; 1511, 3?; 1561, 2+ ; 1791, 6+; 2084, 2+ ; 2093, 5?; 2186, 1?; 2204, 4; 2644, 1. Mixing ratios were determined for six γ-transitions. 相似文献
20.
Directional correlation measurements (e-e, e-γ) have been performed on 182W. The multipole mixing ratios have been measured for the 2γ+2?2g+0 and 4γ+2?4g+0 transitions and a 6+6-6g+0 transition in the decay of 182Ta and 182Re. The mixing ratio of the 2β+0-2g+0 transition is discussed. A strong mixing of the 4β+ and 4γ+ states is suggested. 相似文献