丰中子核107Ru的集体转动带

通过对²⁵²Cf自发裂变产生的瞬发γ谱的测量,对丰中子奇A核¹⁰⁷Ru的高自旋态集体转动带重新进行了研究,建立了新的能级纲图.将基带转动带的自旋态扩展到27 2h,证实并扩展了以前发表的基于中子h_11/2激发产生的集体转动带,并新观测到一个基于(9/2^－)能级的集体转动带.研究结果澄清了早期发表的结果与近来别人发表的结果之间的矛盾,对新建立的¹⁰⁷Ru能级结构的某些重要特征进行了讨论.     

Gamma-gamma directional correlations and coincidence studies in154Gd

The intensities, placements andE2/M1 mixing ratios of transitions in the decay of¹⁵⁴Eu have been carefully studied to provide accurate data for microscopic calculations. Coincidence relationships in the decay of¹⁵⁴Eu have been studied extensively with a multiparameterγ-γ coincidence system with two large volume Ge(Li) detectors. Spectra in coincidence with twenty energy gates were analyzed. Twenty-nine new coincidence relationships were established and confirmed most, but not all, of several levels previously assigned by energy fits only. From an analysis of coincidence spectra and singles spectra with a 18% efficiency Ge(Li) detector new information on the gamma-ray intensities were obtained. Precise values of theE2/M1 mixing ratios of transitions from the gamma- and beta-vibrational bands to the g.s. band have been determined fromγ-γ directional correlation measurements with a NaI(Tl)-Ge(Li) detector coincidence system. Mixing ratios were obtained for a number of other transitions including those fromK ^π =0^? and 2⁺ bands from direct and skipped cascade correlations.     

Identification of one-phonon and two-phonon γ-vibrational bands in odd-ZNb nucleus

Collective bands in the neutron-rich ¹⁰³Nb nucleus have been investigated by measuring prompt γ-rays following spontaneous fission of ²⁵²Cf. Three new bands have been identified. The band based on the 716.8 keV level is proposed as a candidate for the Kπ=9/²⁺$K^{\pi }=9/2^{+}$ one-phonon γ  -vibrational band, and the band built on the 1282.1 keV level is proposed as a candidate for the Kπ=13/²⁺$K^{\pi }=13/2^{+}$ two-phonon γ-vibrational band. The two-phonon γ-vibrational band is the first such band identified in odd-Z nuclei.     

Multipole mixing ratios of transitions in Te

Gamma-gamma directional correlation measurements were made on nine transitions in ¹²⁴Te with a NaI(Tl)-Ge(Li) detector arrangement and multichannel analysis. The multipole mixing ratios obtained were δ(646) = 0.000±0.001, δ(714) = 1.5_−0.3^+0.6, δ(723) = −3.3±0.2, δ(1437) = 3.7_−2.0^+2.7, δ(1489) = −3.4_−1.5^+0.9, δ(968) = −0.03_−0.05^+0.06, δ(1368) = −0.045±0.090, δ(1045) = 0.041_−0.041^+0.047, δ(1691) = −0.02±0.01, and δ(2091) = 0.00_−0.03^+0.02. The first δ is M3/E2, the next three are E2/M1, and the last five are M2/E1. The retardation (a factor of approximately 50) of the crossover to cascade transitions from the 2039 keV, third 2⁺ level to the second and first 2⁺ levels is essentially the same for both the M1 and E2 components. In addition, spin and parity assignments of 2⁺ were made for the 2039 and 2092 keV levels.     

On-line nuclear orientation of70As

On-line nuclear orientation was performed on⁷⁰As. Anisotropy data have been obtained at 8.7mK for 29 gamma transitions. Multipole mixing ratios have been extracted for 17 transitions. Our results are in good agreement with existing data for the ten previously measured transitions. Our first time data for the 1496 keV, 2⁺→2⁺ γ-ray suggest the 2536 keV level is a good candidate for a mixed symmetry level.     

丰中子核113Ru集体转动带的识别

通过对重核²⁵²Cf自发裂变产生的瞬发γ谱的测量,对非常丰中子核¹¹³Ru的能级结构进行了研究,建立了较高自旋态的能级纲图,识别了基于中子h_11/2轨道激发产生的集体转动带,最高自旋态达31/2h.还发现了另一个可能基于9/2^－能级的集体转动带,对新建立的¹¹³Ru的集体带的一些重要特性进行了讨论.