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1.
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   

2.
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   

3.
The 6? and 7? isomeric states in 66Ga and 68Ga at 1440.9 and 1229.6 keV, respectively, have been populated with the (13C, 2np) and (15N, n2p) reactions on natural Fe. The half-lives of these states have been measured to be T12(6?, 66Ga) = 57.3 ± 1.2 ns and T12(7?, 68Ga) = 64 ± 2 ns. Using previous data on the hyperfine field of Ga in Fe, the g-factors of these states have been determined by means of the TDPAD method. The results are g(6?, 66Ga) = 0.129 ± 0.003 and g(7?, 68Ga) = 0.105 ± 0.003. These values are in very good agreement with the independent particle model if one assumes the f52, νg92}6?,7? and p32, νg92}6? configurations and uses the empirical proton and neutron g-factors from odd-A neighboring nuclei instead of the Schmidt values. The large disagreements with experiment when Schmidt values are used show that core polarization effects are important in these nuclei.  相似文献   

4.
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   

5.
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   

6.
A partial-wave analysis of the low-mass (π+π?p) system produced in the reaction K?p → K?(π+π?p) at 4.2 GeV/c incident momentum is performed in order to study the two (π+π?p) enhancements around 1500 and 1700 MeV. It is found that the low-mass (π+π?p) system can be described using the spin-parity states JP = 12+, 32? and 52+ only. In the 1500 MeV region contributions are observed from the 12+ wave decaying into p? and the 32? wave decaying into Δ++π?; in the 1700 MeV region contributions are found from the 12+ wave decaying into Δ++π?, the 32? wave decaying into p?, and the 52+ wave decaying into p?.  相似文献   

7.
The cw dye laser excitation spectrum of the A?2Δ(000) ← X?2Π(000) vibronic transition of the CCN radical was observed between 21 205 and 21 335 cm?1 with the Doppler-limited resolution, 0.04 cm?1. The CCN radical was produced by reaction of microwave discharged CF4 with CH3CN. The observed spectrum was analyzed to determine rotational and centrifugal constants and effective spin-orbit and spin-rotation coupling constants for both the A?2Δ(000) and the X?2Π(000) states, and also the Λ-type doubling constants for the X?2Π(000) state. The constants determined reproduce the observed spectrum with an average deviation of 0.0027 cm?1, and are considered to be precise enough for predicting the ground-state microwave transition frequencies. No evidence was found for perturbation in either the A?2Δ(000) or the X?2Π(000) state.  相似文献   

8.
Using a proton beam with an overall resolution of 300–400 eV (FWHM) spins, parities and partial widths were determined for all resonances observed (99 s-wave, 42 p-wave, 106 d-wave and one g-wave resonances). Differential cross sections for proton elastic scattering from 56Fe were measured at proton energies between 3.1 and 4.2 MeV. Spectroscopic factors and Coulomb displacement energies were extracted for the fragmented analogue resonances which correspond to the 52+ (2.506 MeV), 32+ (2.565 MeV) and 12? (2.687 MeV) states in 57Fe. A value of the s-wave proton strength function was deduced.  相似文献   

9.
Some of the low-lying energy levels of 107Ag and 109Ag were excited by Coulomb excitation using α-particles from 4.8 to 7.2 MeV. Transitions to the isomeric state (72+), involving a parity change, were observed both directly in the singles spectra and indirectly by the decay of the isomer. The isomer in both silver isotopes was populated by transitions from the 52? level, which was strongly excited. The observed branching ratio in 109Ag for the 52?72+ transition was (0.315 ± 0.09) % and for the 52?92+ transition was (0.055±0.03) %. The total rate of populating the 72+ level from the 52? level was (0.215±0.04) % in 107Ag. The level schemes have been discussed on the weak-coupling model, allowing admixtures of singleparticle wave functions to account for the weaker transitions.  相似文献   

10.
We have investigated the reactions ppπ+π?a?and ppa?pp+?at 100 GeV/c. The ppπ+π? final state is dominated by diffractive production of a pπ+π? (orpπ+π?) system which shows a strong tendency to form Δ++π? (orΔ++π+). The process ppa?Δ++Δ++ is also observed in this reaction, indicating an energy dependence of s?1.5±0.1. The pp+? channel shows less single diffraction, and has a doubly diffractive component consistent with pomeron factorization. Strong Δ++(Δ++) production is agoain seen, but in contrast to the ppπ+π? channel we also observe considerable ?0 production.  相似文献   

11.
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   

12.
Form factors for inelastic electron scattering for the excitation of the 32?, 52?, 92?, 112? and 152? members of the (f72)3 configuration in 51V are studied by considering the effect of configuration mixing in the shell model. The inclusion of the highly excited configurations which does not contribute to the γ-transitions is shown to give rise to significant modifications of the form factors in large momentum transfer regions. Under the assumption of the static central potential as the residual interactions between protons, good agreement with the experimental data on form factors is obtained by the ordinary force as well as smaller effective charges than the bare charge for higher multipole transitions.  相似文献   

13.
Electromagnetic studies have established that the 32?, 12? ground state doublet in 7Li is well described by the LS coupling shell model, provided quadrupole effective charge is introduced. The results of microscopic calculations for the excitation of the 12? level in inelastic proton scattering shown within indicate that an equivalent renormalization of the 7Li quadrupole neutron transition densities is also necessary. This verifies the assumption which was made in a previous calculation of the cross section for the excitation of the 32? level in the 7Li+24Mg reaction.  相似文献   

14.
The quadrupole interaction for the 5?2, 134 keV state of 197Hg in solid Hg was observed by the e?-γ time differential perturbed angular correlation method. The quadrupole coupling constant νQ=126 (2) MHz is derived. By comparison with experimental quadrupole coupling constants for 199Hg in Hg and HgCl2 as well as for 201Hg in HgCl2 the quadrupole moment of the 5?2, 134 keV state in 197Hg is related to that of the 201Hg ground state, which is known. The value Q(197Hg, 5?2, 134 keV)=0.47(6) b is deduced. This value is not in agreement with the assumption of a f52 shell-model configuration for the 134 keV state. It is consistent with an interpretation of the 5?2 level in terms of the core coupling model of de Shalit.  相似文献   

15.
High resolution spectra of the ν3 band of methane, 12CH4, were recorded by using a “third generation vacuum Fourier interferometer”; a large pressure range (from 0.009 to 10 Torr) with a sample path fixed at eight meters was used, enabling observation of transitions with intensity ratios as low as 110 000. More than 350 forbidden transitions of the ν3 band, including about 125 transitions of the Q+ branch, were unambiguously identified. Of the 277 transitions retained for computations, one-hundred have 11 ≤ J ≤ 16. From combination difference relations using pairs of transitions having the same upper state energy level (forbidden-allowed and forbidden-forbidden pairs were used), 276 independent differences between ground state energy levels could be determined with uncertainties of about 0.001 cm?1.These data yielded the following values for the ground state structure constants of 12CH4 along with their standard deviations (in cm?1): βohc=5.2410356±0.0000096, γohc=(?1±0.00074) 10?4, πohc=(5.78±0.18) 10?9, ?ohc=(?1.4485±0.0023) 10?6, ?ohc=(1.768±0.126) 10?10, ξohc=(?1.602±0.067) 10?11, Thus, for the first time, the scalar constant π0 has been evaluated and ir values have been obtained for the two tetrahedral constants ?0 and ξ0; furthermore, these values are in very good agreement with the ones recently determined from radiofrequency data, i.e., in cm?1: ?ohc=(?1.45061±0.00014) 10?6, ?ohc=(1.7634±0.0068) 10?10, ξohc=(?1.5432±0.0040) 10?11 From these values, the 276 differences can be reproduced with an overall rms deviation equal to 0.0009 cm?1.Finally, the ground state energies of 12CH4 have been calculated for J ≤ 16.  相似文献   

16.
Forty Ω? events have been observed in a large (133 events/βb) experiment at 4.2 GeV/c incident K? momentum. Thirty nine of the events come from the three-body reaction K?p→Ω?K+K0. The Ω? is mainly produced in the forward hemisphere (direction of the incident K?). The lifetime is measured to be τ = (0.75 +0.14?0.11 × 10?10 sec substantially less than the Particle Data Group value of (1.3 ?0.3+0.2) × 10?10 sec. The mass is determined to be 1671.7 ± 0.6 MeV, in good agreement with other determinations. The decay asymmetry parameter α (for the decay mode Ω? → ΛK?) is found to be ?0.2 ± 0.4.  相似文献   

17.
High spin states in 191, 192, 193, 195, 197, 199Hg were investigated by observing γ-rays and conversion electrons in the compound reactions 192, 194, 198Pt(α, xn) and192Pt(3He, 4n). In 197Hg the decoupled band built on the 132+ state and the semi-decoupled negative-parity band are observed up to Iπ = 412+and332?, respectively. A careful investigation of 199Hg revealed no new high spin states above the previously known levels with Iπ = 252+and312?. Half-lives were determined for the 10+, 7?, 8? and 16? states in 192Hg, the if332+states in191,193Hg and the (frc states in 191, 193, 195, 197Hg. The systematics of the level energies and B(E2) values for the positive-parity ground and 132+ bands and the negative-parity semi-decoupled bands in 190–200Hg is discussed.  相似文献   

18.
The 12?[521] and72+[633] one-quasiparticle bands in the N = 99 nucleus 171Hf have been identified to spins of about 452 using (heavy ion, xn) reactions. The moments of inertia of these bands are consistent with the absence of backbending in the N = 98 core nucleus. The half-life of the 52?[512] intrinsic state was measured as 63.6 ns. The strength of the 52?[512] → 72+[633] E1 transition is discussed. Two three-quasiparticle isomers with spins and parities 192+and232? have been identified and their suggested configurations are a 72+[633] neutron added to the 6+ and 8? two-quasiproton states of the core. The moment of inertia of a rotational band based on the 232? isomer supports this suggestion, and shows the effect of partial rotation alignment of the i132 neutron.  相似文献   

19.
The half-lives of the 72? states at 522.6 and 393.9 keV in 113Cd and 115Cd have been determined to be 0.322±0.012 and 0.75± 0.03 ns, respectively. Values of the B(E2, 72?112?) and the energy difference E72? ? E112? in odd Cd (A = 113–119) are compared with those in neighbouring even Cd. The level properties are interpreted in the framework of the triaxial rotor model.  相似文献   

20.
A γ-decay scheme for levels in 209Pb up to 4.13 MeV of excitation has been established by means of the reaction 208Pb(d, pγ)209Pb. In high efficiency p-γ coincidence measurements γ-cascades have been observed from the single-particle states and from core-excited states with very small single-particle strength. Assuming a qualitative validity of the weak-coupling model spins and main configurations of particle-core states can be deduced from their γ-decay. The Jπ = (32?, 52?or72?, 112?, 152?) members of the g92?3? multiplet could be located. A systematic manner of doublet splitting is found for the lowest states with main configuration (p12)?1?3210Pb (0+, 2+, 4+, 6+, 8+). A new decay branch of the g72 single-particle state is attributed to an admixture of quadrupole core vibration.  相似文献   

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