首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 968 毫秒
1.
The 103Ag nucleus has been studied using the 103Rh(α, 4nγ)103Ag and 103Rh(3He, 3nγ)103Ag reactions. A set of standard in-beam measurements involving relative excitation function measurements of γ-rays, γ-γ-Δt coincidences, conversion electron measurements and angular distribution and linear polarization measurements of emitted γ-rays have been performed. Excited states with spin values up to 272 are populated in this nucleus. Among these excitations a positive-parity band built on the Jπ = 72+or92+ state can be distinguished. This band has similar properties as the band observed in 105Ag. The experimental data on the band in 103, 105Ag are compared to the prediction of the Nilsson model with Coriolis coupling at intermediate deformation ε = 0.10?0.15. Energy levels of the positive-parity bands are reproduced satisfactorily by the calculations assuming either a K = 72+ [413] or K = 92+ [404] band head. However, electromagnetic properties of the levels, branching and mixing ratios, are better reproduced when assuming the K = 72+ band head. Attenuation of the Coriolis interaction was introduced in order to improve the fit of the calculated energies of the levels to the experimental values.  相似文献   

2.
Gamma-ray angular distributions, nγ angular correlations, γγ coincidences and Doppler-shift attenuations have been measured in the 42Ca(α, )45Ti reaction. In addition to the known positive-parity levels forming the Kπ = 32+band, the Kπ = 12+ band members are identified in 45Ti. They are the 12+, 32+ ,52+and72+ levels at 1565 keV, 1958 keV, 2258 Reduced transition probabilities are obtained for the γ-decays of these levels as well as for those of the Kπ = 32+ band members. The excitation energies and transition probabilities are well reproduced by a rotation-particle-coupling model calculation with deformation parameter β = 0.30–0.35.  相似文献   

3.
Lineshape and intensity measurements were made on the overtone band (v = 2 ← 0) of nitric oxide (NO) using a tunable difference-frequency laser system. Self- and N2-pressure broadening coefficients were obtained at 296 K, and a small amount of collisional, or Dicke, narrowing (which reduces the Doppler width by ~9% at 50 Torr) was also evident. The pressure broadening observed for the 2Π32 transitions was larger than that of the 2Π12 for corresponding J by about 7%, so an empirical scaling law model was fit to the broadening coefficients to determine the role of interstate (spin-flipping) collisions. A small collision-induced asymmetry in the Λ-doublet transitions of the 2Π12 level was also observed. The measured line intensities yield an integrated band intensity of 1.878(?40+90) cm?2 atm?1 at 296 K and a Herman-Wallis F factor which determines the relative signs of terms in the dipole moment expansion.  相似文献   

4.
An elastic Kπ partial-wave analysis is presented. It is based on high statistics data for the reactions K±pK±π+nand K±pK±π?Δ ++at 13 GeV obtained in a spectrometer experiment performed at SLAC. For each reaction, a t-dependent parametrization of the production amplitudes provides information on both the Kπ mass dependence of the production mechanisms and on Kπ scattering. Knowledge of the t-dependence then allows a calculation of the Kπ partial-wave amplitudes for Kπ masses from 0.7 to 1.9 GeV. The results of such analyses using data for (i) the neutral recoil reactions, (ii) the Δ++ recoil reactions, and (iii) both neutron and Δ++ recoil reactions simultaneously, are presented. Besides the leading JP = 1?, 2+, and 3? resonances at MKπ = 0.896, 1.434, and 1.78 GeV, there is evidence in two of the four possible partial-wave solutions for a broad P-wave resonant-like structure in the region of 1700 MeV. The I = 12 S-wave magnitude rises slowly and smoothly to a maximum near 1400 MeV, but then decreases rapidly between 1400 and 1600 MeV. This structure is strongly indicative of an S-wave resonance near 1450 MeV. The charge-two Kπ reaction is dominated by S-wave scattering with a total cross section decreasing from 4 mb at 0.9 GeV to 2 mb at 1.5 GeV. Both the I = 12 S-wave below 1400 MeV and the I = 32 S-wave are well described by an effective range parametrization.  相似文献   

5.
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   

6.
7.
Rotational bands up to high-spin members in odd-neutron Hf nucleides are studied by in-beam spectroscopy using (α, xn) reactions on isotopically enriched Yb targets. The 12? [521], 52? [512], and the 72+ mixed positive-parity (mainly 72+ [633]) bands were observed in 173Hf and 175Hf while the 72? [514], 92+ (mainly 92+[624]), and the 3QP(K = 232+) bands were studied in 177Hf. The analysis of the band structure within the Nilsson model is extended to also include adjacent odd Hf nuclei making it possible to follow these bands through five isotopes of Hf.  相似文献   

8.
9.
Lifetimes of low-lying states in 19F were measured using the Doppler-shift attenuation method through the 15N(α, γ)19F reaction. Values of τm = 3700 ± 700 fs (1.35 MeV), 140 ± 15 (1.46), 19 ± 7 (4.00) and 63 ± 19 (4.03) were obtained for the lowest 52?, 32?, 72? and 92? members, respectively, of the Kπ = 12? rotational band and 5 ± 3 fs (1.55 MeV) and 370 ± 25 (2.78) for the 32+ and 92+ members of the Kπ = 12+ ground-state band. For the Doppler-shift attenuation analysis correction factors of the nuclear and electronic stopping powers were determined by measuring the Doppler-shift attenuation and γ-ray line shape of the 2.78 → 0.20 MeV transition and range values of 100, 200. 300 and 370 keV 19F nuclei in tantalum. All calculations were done with Monte Carlo methods. The transition strengths are discussed in terms of different theoretical predictions.  相似文献   

10.
From a study of (p,t) reactions on 31P and 30Si it is suggested that in 29P the states with Jπ=121+ and 122+, the pair 322+, 521+, and the pair 723+, 921+ are related by weak coupling of a s12 proton with the states 01+, 02+, 21+ and 41+ respectively of 28Si. Completely atypical L = 2 angular distributions have been obtained for the 321+ and 522+ states in 29P and it is suggested that this is due to contribution by two-step processes.  相似文献   

11.
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   

12.
Measurements were made of elastic and inelastic proton scattering on 207Pb targets in the energy range from 11.1 to 14.4 MeV. The scattering to the 12? ground state and to the 32? and 52? exciced levels was analyzed in terms of a 0+ analogue resonance interfering with the non-resonant background and with the contribution from the 3? resonance. The resonance parameters were determined together with the magnitude and relative sign of three background components.  相似文献   

13.
The elastic and inelastic scattering of 12C from 19F leading to the 12+ (gs), 52+ (197 keV), 32+ (1.554 MeV) and 92+ (2.780 MeV) states has been studied at E(12C)=30?60 MeV. The angular distributions for the 52+and32+ transitions are almost in phase with those of the elastic scattering and cannot be reproduced with the DWBA and CC caculation using collective form factors.  相似文献   

14.
15.
The 169Tm(t, α)168Er reaction has been studied using 17 MeV polarized tritons from the Los Alamos National Laboratory tandem Van de Graaff accelerator. The α-spectra were analyzed with a Q3D magnetic spectrometer. The overall energy resolution was typically ~ 15 keV (FHWM) and angular distributions of cross sections and analyzing powers were obtained for levels up to ~ 2.7 MeV. The fact that spins and parities for all levels up to ? 2 MeV were previously known from an extensive series of (n, γ) studies made it possible to determine specific two-quasiproton structures for many bands from the present results. The Kπ = 2+ γ-vibrational band was found to have a large 32+ [411]p + 12+[411]p admixture, consistent with the predicted microscopic composition of this phonon, but no 52[413]p ? 12+ [411]p component was observed. The Kπ = 04+ band at 1833 keV has ~ 25% of the 12+ [411]p ? 12+[411]p two-quasiproton strength. This is in excellent agreement with the Soloviev model but is inconsistent with the interacting boson model, in which the Kπ = 04+ band is composed almost completely of multiphonon configurations that should not be populated in a single-nucleon transfer reaction. The Kπ = 4?, 72?[523]p + 12+ [411]p two-quasiproton and the Kπ = 4?, 72+[633]n + 12?[521]n two-quasineutron states are mixed strongly with each other, but the two Kπ = 3? bands composed of antiparallel couplings of the same particles are not. A good qualitative explanation of this mixing pattern is provided in terms of the effective neutron-proton interaction.  相似文献   

16.
The results of integral precession measurements are reported for 32+ and 52+ excited states in 123,125Te. The measurements were made using the ion implantation perturbed angular correlation technique by recoiling the excited nuclei into polarized iron. The measured mean lifetimes and g-factors are: 123Te (440 keV, 32+) τ = 39±4 ps, g = 0.34 ± 0.06; (505 keV, 52+) τ = 26±3 ps, g = 0.04±0.025; and 125Te(443 keV, 32+) ρ = 27±3.3 ps, g = 0.39±0.06; (464 keV, 52+) g = 0.12±0.04. The results are compared with theoretical predictions.  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 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   

19.
The high resolution absorption spectrum of CO has been reinvestigated in the Hopfield helium continuum region, particularly from 960 to 1080 Å. The Rydberg state 3E1Π was extended to v = 2, and other Rydberg states, 3dσ 3Σ+ and F1Σ+, 3dπ 1Π, and 4sσ 3Σ+ and 1Σ+, which are converging to the X2Σ+ ground state of CO+, have been identified. The rotational structures of only five bands among the observed ten Rydberg bands have been analyzed.  相似文献   

20.
Differential cross section and analyzing power angular distributions for the elastic scattering and inelastic scattering to the 2+ state at 4.44 MeV and the 1+ state at 12.7 MeV have been measured at incident proton energies varying from 19.15 to 23.34 MeV in 200 keV steps. Elastic scattering data are analyzed using an averaged optical model. Coupled-channel calculations reproduce roughly the 2+ data. The rapid variation of the data concerning the 1+ state is explained by virtual excitation of giant resonances. For each value of the incident energy, the coupling strength for each resonance is found by fitting the experimental angular distributions. The analysis assuming a weak coupling in the compound system gave a satisfactory fit to the cross section but a poor reproduction of the analyzing power. The assumption of a strong coupling in the 13N system allowed a good fit of all data. The angular distributions are dominated by the E1 resonance, whose 12+ component exhausting more than 37 % of the energy weighted sum rule, explains the isotropy of the cross section below 22 MeV. A 72+ resonance (15 % EWSR) is located at 19.9 MeV. The 52? resonance with its maxima at 20.2 and 21.4 MeV, exhausts about 18 % of the sum rule, which is in good agreement with the results of previous works.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号