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 22 毫秒
1.
TheK-internal conversion coefficients have been measured by the XPG technique for a number of low energyγ-ray transitions whose energies do not exceed theK-binding energies by more than 4 keV. Using Si(Li) detectors in singles and coincidence arrangements, the following results were obtained: 63.1 keV El in169Tm(αK=1.02±0.15), 72.0 keV E1 in187Re (0.75±0.05), 57.8 keV M1 in162Ho (11.42±0.67), 56.6 keV M1 in164Ho (12.04±0.70), and 67.1 keV M1 in174Lu(10.25±0.58). The experimental results are compared with the theoretical calculations which include transition energies down to 1 keV above threshold.  相似文献   

2.
The half-lives of the following intrinsic states in deformed odd-mass nuclei has been measured by delayed coincidences with a time-to-amplitude converter:
  1. 5/2 5/2+[642] at 86.5 keV in155Gd:T 1/2=6.7±0.3 ns, which results in the determination of theE1,ΔK=1 transition probability to the ground state 3/2 3/2?[521] and first rotational state 5/2 3/2?[521], yielding hindrance factors ofF N ≈5.5 and ≈1.8 (F W =3.1×104 and 2.3×104) respectively.
  2. (3) 5/2 5/2?[512] at 191.4 keV in169Yb:T 1/2=3.35±0.15 ns and at 122.39 keV in171Yb:T 1/2=265±20 ns which results in the determination of the transition probabilities of theE1,ΔK=1 transitions to the ground states 7/2 7/2+[633], of theK-forbiddenM1 transitions to the 5/2 and 3/2 1/2?[521] and of theE2 transitions to the 5/2, 3/2 and 1/2 1/2?[521] states in both nuclei.
TheE1 transition probabilities are compared to the transitions between the same Nilsson states in173Yb and175Hf discussing the influence of the position of the Fermi surface — obtained from recent stripping and pick-up reactions — on these transition probabilities. Additional information on the decay scheme of171Lu→171Yb is obtained by delayed coincidence measurements. For testing the used time-to-amplitude converter the well known half-lives of the 482 keV level in181Ta (T 1/2=10.4±0.3 ns) and of the 279 keV level in203Tl (T 1/2=0.285 ±0.015 ns) were measured, in good agreement with other measurements.  相似文献   

3.
The half lives of the levels at 4,714 keV and 4,415 keV in132Sn have been determined to (20.2±0.8) ns and (4.0±0.3) ns, respectively. The half life of the 4,415 keV level in connection with the existence of aγ transition from this level into the ground state furnishes evidence for the doubly magic character of this nucleus. The transition probabilities which result from both half lives agree well with the theoretical predictions and, thereby, provide information on the structure of the positive parity states in132Sn.  相似文献   

4.
Bombarding a85Rb target by 27 MeVα-particles the following half-lives of excited states in different nuclei have been determined by means of the generalized controid shift method: in87Y,T 1/2(2827.1 keV)=0.75±0.10 ns,T 1/2(2675.9 keV)=0.25±0.10 ns,T 1/2(3595.3 keV)=0.5±0.2 ns andT 1/2(2986.9, 3094.4 keV)<0.1 ns; in88Y,T 1/2(232.1 keV)=0.8±0.1 ns and in85Rb,T 1/2(151.2 keV)=0.6±0.1 ns. In87Y, the members of the doublet (vg 9 2/?2 )8+ (πp1/2) are identified. E2 transition rates 21/2+? 17/2+ in odd A≈ 90 nuclei are shown to represent essentially core transitions. Evidence for the existence of seniority-five configurations is found.  相似文献   

5.
By means of the generalized centroid-shift method, the following half-lives were determined:T 1/2(3045 keV)=3.7±0.3 ns in113Sb using the reaction104Pd(12C,p2n) as well asT 1/2 (1322.8 keV)=3.5±0.3 ns,T 1/2(2779.8 keV) =0.50±0.15ns,T 1/2(2874.9 keV)<0.2 ns andT 1/2(3072.9 keV)<0.1 ns in117Sb using the116In(α, 2n) reaction. Three-quasiparticle configurations of the type πd 5/2ν(h11/2 d 3/2) in113,117Sb are found to dominate in the wave functions of the 19/2? states at 3045 and 2780 keV in113Sb and117Sb, respectively. TheB(E2, 19/2? → 15/2?) values in113–119Sb are discussed.  相似文献   

6.
Two new isomers have been observed in180Os. A high-K isomer withI, K ≧20 and a half-life ofT 1/2=12+4 ns have been established. It deexcites via two transitions into the 18+ level of the yrare band indicating an unusually smallK-hindrance factor. Evidence for an isomer withI, K>16 and a half-life ofT 1/2=41±10 ns was found. A half-life of 17±3 ns was measured for the previously known 7? state at 1862 keV. The decay scheme of the previously known 7? isomer at 1928 keV has been extended and a revised version is presented.  相似文献   

7.
Using theγ-radiation of 748 and 28 keV the half-lives of the first two excited states in51Cr at 748 and 776 keV have been measured by a pulsed beam technique. The interesting states were populated by the reaction51V(p, nγ)51Cr at 4 MeV proton energy. The half-lives were found to beT 1/2(51Cr, 748 keV)=(7.35±0.03) ns andT 1/2(51Cr, 776 keV)=(5.53±0.07) ns. The influence of the 28 keV transition between the two levels upon the lifetime of the 748 keV state has been investigated. The 776 keV-state populates the 748 keV state only by 8.4%. The lifetime of the 776 keV state, therefore, cannot account for the anomalous long lifetime of the level at 748 keV as has been proposed by Bartholomew et al.  相似文献   

8.
The electron capture of176m Lu to the ground state and to the first excited state of176Yb has been observed by measuring the YbK x-rays and the 82,2 keV gamma-rays from the gamma decay of the first excited state in176Yb. With the data of the 88,36 keV gammarays following the beta decay of176m Lu to the first excited state of176Hf the electron capture/beta decay ratio of176m Lu was found to be (0,95±0,16)·10?4. The electron capture branching ratio to the ground state and to the first excited state of176Yb was found to be 40/60±30%. By analyzing the 88,36keV gamma-rays and the HfKx-rays the halflife of176m Lu was evaluated to be 3,66±0,04 h. The value for theK-conversion coefficient of the 88,36keV transition was determined from the x-ray/gamma-ray ratio to be 1,19±0,09.  相似文献   

9.
Lifetime measurements of three excited states in100Rh populated by the decay of100Pd have been carried out. A two parameter delayedγ-γ-coincidence experiment using an intrinsic Ge and a plastic scintillation detector resulted in the following values:T 1/2(32.72 keV,100Rh)=(27.6 ±0.6) nsT 1/2(74.8keV,100Rh)=(213.6±2) nsT 1/2(158.8 keV,100Rh)<0.5 ns. For the levels at 32.72 keV and 158.8 keV no former values are known.  相似文献   

10.
The internal conversion subshell intensities of the (21.529±0.014) keV transition in151Eu and the (22.494±0.011) keV transition in149Sm have been determined in a high resolution investigation using a double-focussing iron-core spectrometer. The subshell ratios yielded unambiguousM1+E2 multipole mixtures for both transitions. δ2(E2/M1) for the 21.53 keV transition was determined to be (8.8±0.7)·10?4 and for the 22.49 keV transition to be (5.5±1.2)·10?3.  相似文献   

11.
The work contains the α K internal conversion coefficient measurement by XPG method of 113.8 keV transition in175Lu. We obtained α K =1.82±0.15. The 113.8 keV transition in175Lu supports a large penetration effect, as it can seen from computedλ parameter values.  相似文献   

12.
The lifetimes of several negative-parity states in126,130Xe and132Ba have been determined by means of the generalized centroid-shift method. The reactions124,128Te(α,2n) and122Sn(13C, 3n) have been used. Following results were obtained:T 1/2(2758 keV)=1.3±0.2 ns in126Xe,T 1/2(2060 keV)=0.20±0.10 ns,T 1/2(2104 keV)=0.50±0.10 ns,T 1/2(2376 keV)=0.30±0.10 ns andT 1/2(2973 keV)=4.6±0.4 ns in130Xe as well asT 1/2(2120 keV)=0.40 ?0.10 +0.20 ns in132Ba. A systematics of the B(E2; 7 ? 1 ?5 1 ? ) values in theN=76 nuclei is presented. Electric dipole and quadrupole transition rates are discussed in terms of octupole and quadrupole collectivity. The structure of the 5 1 ? and 7 1 ? states is considered. Nuclear reactions:124,128Te(α, 2 n ),E=26 MeV,122Sn (13C, 3n),E=53 MeV; measuredE γ I γ , γ-r.f. DeducedT 1/2, B(σL) in126,130Xe and132Ba. Ge detectors. Generalized centroid-shift analysis.  相似文献   

13.
Theβ-decays of99Y and99Zr have been investigated with the two recoil fission product separators JOSEF and LOHENGRIN. Half-lives of 1.51±0.08s and 2.1±0.1s respectively, have been determined. Aβ-decaying isomeric state has been observed in99Y. The level schemes of 40 99 Zr59 and 41 99 Nb58 have been established fromγ-ray spectroscopy. Absoluteγ-intensities have been obtained by means of two independent techniques. Halflives of 293±10 ns for the 251.9 keV state and 10.2±1.5 ns for the 614.0 or 667.2 keV level in99Zr have been measured through delayedβ,γ- andγ,γ-coincidence experiments. Values for the spins and parities of the low lying levels in99Zr are proposed in accordance with the systematics of lighter odd Zr isotopes. Spins and partities are assigned to some levels in99Nb fromγ,γ-angular correlation measurements. In this nucleus there is evidence for three-particle configurations of some excited states, where the odd proton is coupled to two neutrons which are in different orbits.  相似文献   

14.
The half lives of the excited levels at 482.2 keV and 615.3 keV in181Ta have been measured by the delayed coincidence technique. In the nanosecond time range (482.2 keV level) the most serious sources of errors are jitter, walk and drift phenomena. To minimize those the time pick-off has been defined carefully by means of modern fast timing detectors and electronics. In the microsecond time range (615.3 keV level) the ratio of true delayed coincidences to chance coincidences influences considerably the final accuracy of the half-life measurements. It has been reduced as much as possible. From a series of independent measurements half lives ofT 1/2=(10.67±0.05) ns andT 1/2=(17.64±0.14) μs have been deduced for the 482.2 keV and 615.3 keV levels, respectively. The results have been compared with other values published before.  相似文献   

15.
Lifetime measurements of two excited states in131Xe populated by the decay of131I have been carried out. Analysis of data, delivered from a delayed γ-γ-coincidence experiment with a Ge(Li)-Plasticdetector combination, resulted in the following values:T 1/2 of 341.2 keV level in131Xe: (2.15 ± 0.07) nsT 1/2 of 404.8 keV level in131Xe: <0.5 ns.  相似文献   

16.
Prompt and delayedγ-γ-coincidences were measured after slow neutron capture in185Re by use of Ge(Li)-detectors. New isomers were found at 99.4 keV (T1/2=27±7ns) and at ≈330keV (T1/2=17.4±0.7 ns). The evaluation of coincidence data established 10 rotational bands with band heads below 700 keV. The level scheme is discussed in detail: Nilsson assignments are proposed for the band configurations, and calculations of Coriolis mixing andγ-transition probabilities are presented which reproduce the experimental level energies and transition intensities very satisfactorily.  相似文献   

17.
The parity mixing in nuclear states was studied by measuring the circular polarizationP of the γ-radiation emitted from unpolarized nuclei. The analyzer was a “radial transmission magnet” of high symmetry. With 4 NaI scintillation counters and the current integration method 4 independent results were obtained simultaneously. The polarimeter efficiency was determined via the Quadratic Compton effect. Studies of the polarized bremsstrahlung with170Tm,177Lu and198Au sources served as tests for the calculated corrections due to the bremsstrahlung effect. Our results for the circular polarization are:P=?(2.0±0.4) · 10?3 for the 501 keV transition in180Hf,p=+(1±4) · 10?6 for the 482 keV transition in181Ta andP=+(1±7) · 10?6 for the 279 keV transition in203Tl. Thus, in the case of180Hf, the existence of the parity mixing in nuclear states was confirmed.  相似文献   

18.
Gamma-gamma directional correlations have been investigated for the cascades of 135-30 keV and 135-32 keV in201Hg from the decay of201Tl. A combination of NaI (Tl) and Si (Li) detectors was used for the experiments. Spin values ofI=1/2, 3/2 and 1/2 have been assigned to 1.58, 32.19 and 167.49 keV energy levels. In addition, the relative intensities of theγ rays have been measured with a Ge (Li) detector system. The results are 2.2±0.2, 2.2±0.2, 26.5±1.3, 1.6±0.1 and 100 for theγ rays of 30.60, 32.19, 135.34, 165.88 and 167.43 keV energies, respectively.  相似文献   

19.
The half-life of the 53.2 keV level in214Bi has been measured asT 1/2=0.52±0.15 ns, furtherT 1/2(295.2 keV and 351.9 keV levels)≦0.10 ns was estimated. TheB(M1,2?→1?) transition rates within theπh 9/2 vg 9/2 multiplet in210,212,214Bi are found to decrease rapidly with increasing neutron number, reaching in214Bi a value as low as those typical for intraband M1 transitions in deformed odd-odd nuclei.  相似文献   

20.
The level scheme of102Rh has been investigated by the102Ru(p, nγ) reaction in the proton energy range 3.1 MeV≦E p≦6 MeV. Excitation functions,γ-γ coincidences and pulsed beam measurements have been performed and a level scheme including 33 excited states up toE x≈650 keV has been constructed. Theγ-branchings of several levels have also been measured. The lifetimes of 5 excited states have been determined with the centroid-shift method:τ m(105.2 keV)=(1.3±0.3) ns,τ m(123.7 keV)=(0.6±0.3) ns,τ m(178.6 keV)=(1.5±0.3) ns,τ m(208.7 keV)=(0.5±0.3) ns,τ m(359.6 keV)=(0.8±0.4) ns. Upper limits have been placed for the lifetimes of 20 other levels.  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