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1.
Double differential cross sections for electron-3He scattering leading to continuum states were measured between break-up threshold and the region of quasi-free interaction in a momentum transfer range of 1 fm?2 < ¦q¦2 < 2.5 fm?2. The cross sections for the quasi-free scattering calculated in plane-wave impulse approximation were found to be in good agreement with the experimental results for momentum transfer ¦q¦ > 1.5 fm?1.  相似文献   

2.
Levels at 7.17, 8.29, 8.96 and 9.88 MeV in 19F have been assigned spin and parity 112?, 132?, 112? and 112?, respectively, from resonance strength and γ-ray angular distribution measurements employing the 15N(α,γ) 19F reaction. An earlier assignment of 112+ to the 8.96 MeV level is incorrect. The measured properties of the 112? states are compared with the results of both SU (3) shell model and cluster model calculations.  相似文献   

3.
Excitation functions of γ-rays from the 75As(p, n)75Se reaction were measured with 2.0 to 3.6 MeV protons to establish the level scheme of 75Se up to about 1.5 MeV excitation energy. Internal conversion electrons following the same reaction were measured at 4.5 and 5.0 MeV proton energy. Using theoretical predictions of the statistical compound nucleus model together with deduced internal conversion coefficients, unique spin assignments were obtained for the 112.5(72+), 427.9(52?) and 663.9(52?) keV levels. Probable spins were proposed to the 286.6 (32? for one of the doublet and 52? or 72? for the other), 579.4 (12? or 32?, 585.8(92? or 112? and 747.6 (52? or 72?) keV levels. Alow-lying 92+ level was tentatively assigned at 133.2 keV energy. It was found that a low-lying 12? level which appears systematically in other odd Se nuclei is absent in 75Se.  相似文献   

4.
The elastic and inelastic scatterings of 35.5 MeV 4He ions from 9Be are analyzed in the strong coupling limit by the coupled channel method. A good account of the ground-state (K = 32?) band is obtained, in agreement with the electromagnetic properties of this band. Data for three states of the K = 12+ band are analyzed, yielding much larger isoscalar dipole scattering amplitudes for the 32+ state than are obtained by electron scattering for electric dipole transitions.  相似文献   

5.
The 40Ca(α, 3He) reaction has been studied at 36 MeV incident energy. About fifty levels have been observed up to 7.1 MeV excitation energy and angular distributions were measured from 6–60° using a split-pole spectrometer. A local zero-range DWBA analysis has been carried out, and the deduced l-assignments and spectroscopic factors are compared with those obtained from previous neutron stripping experiments. Core-excited states in 41Ca with a [3? ? f7,2], [2+ ? f7,2] and [5? ? f7,2] component previously observed in inelastic scattering experiments, are selectively excited by the (α, 3He) reaction. Their angular distributions are compared with coupled-reaction-channel calculations, assuming a pure two-step reaction mechanism. The agreement between theory and experiment may be considered as rather satisfactory for a number of levels. In particular the 12+and32+ levels and the high-spin states with Jπ = 92?, 112+, 152+and172+ are successfully described within the framework of the weak-coupling model.  相似文献   

6.
Resonances in the reaction 56Fe(p, γ)57Co have been surveyed over the energy range 1.2 ? Ep ? 1.5 MeV wherein the analogues of the ground state (Jπ = 12?, 0.014 MeV state (Jπ = 32?) and 0.136 MeV state (Jπ = 52?) of 57Fe are expected to occur. Gamma-ray angular distributions have been used to establish resonance and bound-state spins, and decay schemes have been determined. The analogue resonances appear to be severely fragmented, however the density of resonances of a given spin correlates quite well with (3He, d) results and with the expected analogue-state positions.  相似文献   

7.
The lifetimes of the lowest 32?and52? levels in 103Rh, 107Ag and 109Ag have been measured with the Doppler-shift version of the recoil-distance technique. A beam of 35Cl ions of energy 64 MeV was used to Coulomb excite the target nuclei and eject them from the target. The following lifetimes were obtained: τ(103Rh, 32?, 295 keV) = 14.5 ± 1.5 ps, ρ103Rh, 52?, 357 keV) = 112 ± 10 ps; τ(107Ag, 32?, 325 keV) = 7.2 ± 1.3 ps, τ(107Ag, 52?, 423 keV) = 43 ± 3 ps; τ(109Ag, 32?, 311 keV) = 8.5 ± 1.0 ps, τ(109Ag, 52?, 415 keV) = 50 ± 3 ps. Of t correction factors taken into account the perturbation of the γ-ray angular distribution by the magnetic hyperfine interaction during recoil through vacuum was found to give the largest correction to the measured lifetimes. These lifetimes lead to reduced transition probabilities Bd(E2) for the silver nuclei in reasonable agreement with the predictions of the core-excitation theory.  相似文献   

8.
9.
Nuclear magnetic resonance of oriented 71As and 72As nuclei has been observed in an iron host lattice at low temperatures. The resonance frequencies are vl = 174.96(10) MHz and 282.00(11) MHz respectively for zero external field. Using Bh.f.(FeAs) = 342.9(3) kG the g-factors of the two isotopes are derived as g(71As) = (+)0.6694(7) and g(72As) = (?)1.0789(11). Combining nuclear orientation data with these results the spin of 71As has been confirmed as I = 52. The magnetic moments of the 52? and 2? states in the As isotopes are discussed in the framework of the shell model with configuration mixing.  相似文献   

10.
Levels of 184W populated in the decay of 8.7 h 184Ta have been studied by a variety of experimental techniques. As a result of β and γ-ray energy and intensity determinations and extensive β-γ and γ-γ coincidence measurements, a detailed 184Ta decay scheme accommodating more than 99.5% of the decay intensity has been established. Intense β-ray groups of end-point energies 1165±26 and 1123±26 keV populate levels in 184W at 1699 and 1746 keV, which de-excite predominantly to the 8.3 μs isomeric level at 1285 keV, recently identified as the 12?[510]ν?112+ [615]ν Kπ = 5? band origin. The 1699 keV level also de-excites to members of a 12?[510]ν?72 [503]ν Kπ = 3+ band based at 1425 keV. New information about the properties of the γ-vibrational and K = 2 octupole bands in 184W is presented and the possible configurations of the levels directly populated in the β? decay are discussed. The configuration 72+[404]π ?32? [512]ν Kπ = 5? is indicated for the 184Ta ground state.  相似文献   

11.
High spin states of 57Co have been studied via prompt γ-ray spectroscopy in the reactions 48Ti(12C, p2n) and 54Fe(α, p) at 26–48 MeV and 12–24 MeV, respectively. The energies and decay modes of these levels were determined from the analysis of γ-ray singles and γ-γ coincidence spectra, excitation functions, angular distributions and correlations. The relevant lifetimes were measured by the Doppler-shift attenuation method. The new levels established in this work are at 4037, 4814 and 5918 keV with the most probable Jπ assignment of 152?, if 172? and 192?, respectively. The previously known level at 2524 keV was assigned to have Jπ = 132?. These together with the known 92?(1224 keV) and 112?(1690 keV) levels constitute the yrast states of 57Co. The measured lifetimes of the above six levels are (in order of increasing energies) 0.085±0.030, 0.32±0.10, 0.16±0.06, 0.10?0.07+0.06, 1.5?0.54 and 0.17?0.07+0.08 ps, respectively. Comparisons with some theoretical calculations are presented.  相似文献   

12.
Angular distributions of the vector analyzing power and the absolute cross section were measured for the 58Ni(d, p)59Ni reaction at a deuteron energy of 10 MeV. The observed j-dependence of the vector analyzing power allowed unambiguous spin assignments for the following states in 59Ni with excitation energies in MeV: 0.0, 32?; 0.341, 52?; 0.465, 12?; 0.879, 32?; 1.303, 12?; 1.686, 52?; 3.454, 32?; 3.858, 32?; 4.495, 52+. The data are well reproduced by DWBA calculations employing deuteron and proton optical model parameters obtained from analyses of elastic scattering cross sections and polarizations. A tentative spin assignment of 92+ is made for the level at 3.061 MeV. A 52+ assignment to the level at 3.538 MeV is suggested on the basis of the empirical behavior of the j-dependence of the vector analyzing power for l = 2 transitions. Measurements of the vector analyzing power for the four low-lying 59Ni states formed by l = 1 transfer were made for angles from 2.5° to 15° using a magnetic spectrograph. A very strong j-dependence was observed for these far-forward-angle measurements in agreement with DWBA predictions.  相似文献   

13.
14.
Resonances in the 50Cr(p, p′γ) reaction were investigated with the TUNL high resolution system. All previously observed p-wave resonances between Ep = 2.00 and 3.03 MeV were studied. Measurement of the p' and the γ-ray angular distributions provides sufficient information to determine unambiguously the J-value of the resonance and the magnitude and relative phase of the inelastic decay amplitudes. Expressions are given for the appropriate angular distributions and for the transformation between the channel spin and the total angular momentum representation. Experimental results are presented for 24 p-wave resonances in 51Mn including decay amplitudes and relative phases for 1632? resonances. Six resonances formerly assigned 12? are reassigned 32?. Inelastic spectroscopic factors were determined for two analogue states. Proton strength functions were evaluated from both the elastic and inelastic data.  相似文献   

15.
The level schemes of 98, 99Ru were studied with the reactions 98Mo(α, 3nγ) and 98Mo(α, 4nγ) at Eα = 35 to 55 MeV, using a large variety of in-beam γ-ray detection techniques and conversion-electron measurements. A search for the 3? state was carried out with the reaction 98Ru(p, p′). The ground-state band of 98Ru was excited up to Jπ = (12)+ and a negative-parity band up to (15)?. New levels in 98Ru were found at Ex = 2285 (Jπ = 4+), 2435 (Jπ = (3?, 4+)), 2671, 3540, 4224, 4847, 4915 (Jπ = (12)+), 4989 (Jπ = (12+)), 5521 (Jπ = (13)?), 5889, 6591 (Jπ = (15)?), and 7621 keV. New unambiguous spin and parity assignments were made for the levels at Ex = 2014 and 3852 keV, as Jπ = 3+ and 9?, respectively. New levels in 99Ru were found at Ex = 1976, 2021 (Jπ = (152+)), 2393, 2401 (Jπ = (172+)), 2875 (π = (+)), 3037, 3201 (Jπ = (232)?), 3460 (J = (172)), 3484 (Jπ = (212+)), 3985, 4224 (Jπ = (272?)), and 5359 keV. The 1070 keV, Jπ = 112? level in 99Ru has a half-life of 2.8 ns. A strongly excited negative-parity band is built on this level. A positive-parity band based on the ground state was excited up to Jπ = (212+). The level schemes are well reproduced by the interacting boson model in the vibrational limit.  相似文献   

16.
Yrast states of 41K and 41Ca have been investigated with the 26Mg(18O, p2nγ)41K and 26Mg(18O, 3nγ)41Ca reactions at a beam energy of 34 MeV. Gamma-gamma coincidence, γ-ray angular distribution and linear polarization measurements were performed with a Ge(Li)-NaI(Tl) Compton suppression spectrometer and a three-crystal Ge(Li) Compton polarimeter. Unambiguous spin-parity assignments of Jπ = 72+, 112+, 112?, 132+, 152? and 192? to the 41K levels at Ex = 1.68, 2.53, 2.76, 2.77, 4.27 and 4.98 MeV and of 92+, 112+and152+to the 41Ca levels at Ex = 3.20, 3.37 and 3.83 MeV, respectively, have been obtained. Excitation energies, branching ratios, multipole mixing ratios and transition strengths are reported. The main features of the 41K and 41Ca level and decay schemes are reproduced in a 2p-1h and 3p-2h shell-model calculation.  相似文献   

17.
The electron capture decay schemes of 245Bk and 246Bk have been investigated by measuring the γ-ray and conversion-electron spectra of mass-separated 245Bk and 246Bk samples. The γ-ray spectra were measured with a 25 cm3 Ge(Li) spectrometer and the conversion-electron spectra were measured with a cooled Si (Li) detector. Multipolarities of most of the transitions in 245Cm and 246Cm were deduced. The half-lives of 245Bk and 246Bk were determined by following the decay of the 252.85 and 798.7 keV photopeaks and were found to be 4.90 ± 0.03 d and 1.80 ± 0.02 d, respectively. The α/(α+EC) ratio for the 245Bk decay was measured to be (1.2 ± 0.1) × 10?3. On the basis of the present investigation the following non-rotational states were identified in 245Cm: 72+ [624], 0; 52+[622], 252.85; 12+ 355.95; 32? vibrational, 633.65; and 12+[620], 740.95 keV. The 32? state at 633.65 keV is int as a Kπ = 2? phonon coupled to the i72+[624] single-particle state. Our measurements of 246Bk γ-ray and conversion-electron energies and intensities confirm previous level assignments in 246Cm.  相似文献   

18.
The quadrupole interaction frequencies ω0 = 3eQ1Vzz41(21-1) h? in the 5? state of 118Sn have been measured by time differential perturbed angular correlation technique in Sn, Sb and (95% Sn+5% Sb) environments. The ω0 for 116Sn was determined in Sn environment only. With the help of the known electric field gradient 1) of Sn in a Sn lattice the quadrupole moments have been deduced as Q(5?, 118Sn) = ±0.10(4) b and Q(5?, 116Sn) = ±0.165(60) b. These values together with the known2) quadrupole moment of the analogous 5? state in 120Sn are interpreted in terms of the pure single-particle model. The data exhibit the expected strong systematic variation of QI with the number of particles in the h112. subshell which is being filled with 1, 3 and 5 neutrons in 116Sn, 118Sn, and 120Sn, respectively.  相似文献   

19.
The 152Sm(t, α)151Pm reaction was studied using 17 MeV polarized tritons from the tandem Van de Graaff accelerator at the Los Alamos Scientific Laboratory. The α-particles were analyzed using a Q3D magnetic spectrometer and detected with a helical-cathode position-sensitive counter. The overall resolution was ~ 18 keV FWHM. Measurements of the 150Nd(3He, d)151Pm reaction were made using 24 MeV 3He beams from the McMaster University tandem accelerator. The deuteron spectra were analyzed with a magnetic spectrograph using photographic emulsions for detectors, yielding a resolution of ~ 13 keV FWHM. By comparing the measured angular distributions of (t, α) and (3He, d) cross sections and (t, α) analyzing powers with DWBA predictions it was possible to assign spins and parities to many levels. The present results confirm earlier assignments of rotational bands based on the low-lying 52+ [413], 52?[532], 32+ [411] and12+ [420] orbitals. In addition, states at higher excitation have now been assigned to the 12+[411] and72+ [404] orbitals, and members of the 32+[422], 52+ [402], 32? [541] and72? [523] bands are tentatively proposed. The spectroscopic strengths can be explained reasonably well by the Nilsson model when pairing and Coriolis mixing effects are included.  相似文献   

20.
The g-factors of the 10+ isomeric states in 194Hg and 196Hg have been measured using the in beam IPAD method. The results g(194Hg) = ?0.24(4) and g(196Hg) = ?0.18(9) are in agreement with the value expected for an (i132?2) neutron satructure and clearly contradict the previous assignment as (h112?2) proton configurations. Cranking model calculations show that the neutron excitation energies in the rotating frame agree satisfactorily with the experimental energies and that the proton excitations are expected ≈2 MeV above the experimental yrast line  相似文献   

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