Ag~(110m)的衰变纲图

利用γ闪烁谱仪和γ—γ符合谱仪,我们对Ag~(110m)衰变的γ射线进行了研究;提出了一个修正的衰变纲图,认为Cd~(110)有656kev,1473kev,1540kev,2160kev,2219kev,2476kev和2924kev七个激发能级,包含有能量为448,620,656,679,705,741,764,817,884,936,1384,1473,1504和1560kev的14条γ射线。用符合方法,我们除了证实一般公认为有级联关系的γ射线之间有符合之外,还确定了1560kevγ射线在衰变图中的位置,证实了764kevγ射线应该放在1504kevγ射线的前面,并且指出,817kevγ射线是属于1473kev能级到656kev能级间的跃迁的。此外,还观察到1820kev和2268kev两个峰;经过用吸收方法分析,指出它们是由于低能量的γ射线“堆积”起来的迭加峰。     

γ谱测量中级联符合效应修正研究

从基本概念出发推导出了简单衰变纲图、较复杂衰变纲图和复杂衰变纲图的γ射线级联符合修正公式, 然后用这些公式计算了¹³³Ba和⁶⁰Co的γ射线级联符合修正系数, 同时指出一些文献中所给出的修正公式之不妥.     

101Mo衰变的研究

采用γ–γ–t三参数快慢符合谱仪研究了¹⁰¹Mo¹⁰¹Tc的衰变,利用符合测量结果构造了一个新的¹⁰¹Mo¹⁰¹Tc衰变纲图.首次确定了104.70,105.95,774.15keV γ射线的位置.首次观测到1508.01keV的γ射线并确认了其跃迁位置.     

Yb169的衰变——稀土元素大变形核的激发能级的研究(Ⅰ)

本工作用有铁双聚焦β谱仪、双磁镜β谱仪和γ闪烁谱仪测量了Yb¹⁶⁹的γ射线的内转换和外转换电子线谱、γ闪烁谱和γ-γ符合能谱。定出了Tm¹⁶⁹的14条γ射线的能量和多极性:8.8,20,21,43,63.7(E1),93.9(M1),111(M1),120(E2),131.8(E2),177.5(M1),198(M1),199(M1),240和308(E2)千电子伏。并用正比计数管测量了能量为8.8千电子伏的低能γ射线。在测量结果的基础上拟出Yb¹⁶⁹的衰变纲图。最后将Tm¹⁶⁹与Tm¹⁶⁷,Tm¹⁷¹激发能级的实验数据综合一起,来看它们之间核结构的相似性,并与综合模型所预言的结果相比较。     

Gd159的衰变——稀土元素大变形核的激发能级的研究(Ⅱ)

本工作使用高透射率带铁中间象式β谱仪和闪烁谱仪,测量了浓缩同位素纯Gd¹⁵⁹(半衰期为18小时)的β连续谱,γ射线谱,γ-γ和β-γ符合谱。用磁谱仪观察到3个β分支的能量和相对强度的百分比为962(60.6％),800(15.1％)和600(24.3％)千电子伏;它们相应的log ft是6.7,6.9和6.4。在β-γ符合能谱测量中,除观察到上述3个β分支外,还定出端点能量为440千电子伏的β分支。此外,还定出Tb¹⁵⁹的10条γ跃迁的能量和部份γ跃迁的多极性:27,56(M1),80(M1+E2),107,136(M1),198,225(E1+M2),362(E1)和468千电子伏。内转换系数的测量肯定了362千电子伏γ射线的幅射多极性为E1型。在测量结果的基础上拟出Gd¹⁵⁹的衰变纲图。最后并将Tb¹⁵⁵,Tb¹⁵⁷, Tb¹⁵⁹和Tb¹⁶¹的能级数据综合在一起,利用综合模型来比较它们之间核结构的相似性。     

95Ru的衰变

通过⁹²Mo(a,n)反应产生⁹⁵Ru,对半衰期为1.65小时的⁹⁵Ru的衰变Y谱学进行了研究,观察到了⁹⁵Ru衰变产生的130条γ射线,其中34条是新的.根据符合关系,将新γ射线中的29条放进了衰变纲图,同时确认了原纲图中7条γ射线的位置,发现了⁹⁵Ru衰变子体⁹⁵Tc的3个新能级,给出了⁹⁵Ru新的衰变纲图.     

72Ge40的低激发态能级研究

用低本底反康谱仪(HpGe–NaI)和HpGe–HpGe的三参数符合γ–γ–T系统,对72Ga的衰变γ单谱、符合谱进行了研究,实验共获得2.3×10⁷个符合事件.根据实验结果建立了含有26个能级、87条γ射线的72Ga的衰变能级纲图,其中包含首次测到7条γ射线225.92、826.97、1349.71、1475.32、1667.91、2105.28、2247.39keV和4个能级3248.01、3396.27、3806.10、3864.56keVS并为2939.83keV能级和112.59、937.97、2402.25、2939.95keV4条γ射线的存在提供了证据;实验没有发现113.5、1155.7、1192.4keVγ射线和能级3307.1keV存在的证据。并把317.72keVγ射线的跃迁,由原来的能级3757.26keV跃迁到3439.51keV能级,改为3565.85keV到3248.01keV能级跃迁.     

缺中子120Ba核EC/β+衰变的再研究

利用171MeV ³²S束轰击⁹²Mo靶,熔合蒸发(2n2p)反应合成了¹²⁰Ba核.由氦喷嘴反冲快速带传输系统将反应产物送到低本底区.位于带子两侧的两个平面型高纯锗探测器对反应产物进行了符合测量.经离线数据分析,对早先发表的¹²⁰Ba衰变γ射线予以确认,并补充了19条强度较弱、能量较低的γ射线.建议了¹²⁰Ba的衰变纲图共包括35条γ射线和25条能级.     

73Br的衰变研究

以⁶⁴Zn(¹²C,2np)反应得到⁷³Br,经过氦喷嘴传输系统和快速化学分离后进行了γ单谱、γ-γ符合和角关联测量,得到了⁷³Br的27条γ射线能量和相对强度,其中102.1、137.2、166.2、249.0、345.5、363.8、381.5、385.7和390.2keV 9条γ射线以及192.4、537.4和574.1keV 3条能级为本工作首次测得.建立了⁷³Br的衰变纲图,由log ft值和角关联系数测量值推测了90.4keV能级的自旋.     

207Rn能级结构的实验研究

利用能量为85—95MeV的¹⁶O束流,通过¹⁹⁶Pt(¹⁶O,5n)²⁰⁷Rn反应布居了²⁰⁷Rn的高自旋态.实验进行了γ射线的激发函数、γ射线的单谱、衰变谱和γ-γ-t符合测量.建立了由17条γ射线组成的²⁰⁷Rn能级纲图,并且基于实验测量的DCO系数建议了各能级的自旋值.用一个f_5/2价中子空穴与²⁰⁸Rn核芯耦合定性地解释了²⁰⁷Rn的低位激发态.     

Levels in222Rn

An attempt has been made to observe gamma-rays from the 3^? level of the possible octupole band in²²²Rn occurring in the decay of²²⁶Ra. The gamma-ray energies already known in this decay have been measured with increased precision both in singles measurements and in coincidence with the 186-keV (2⁺ → 0⁺) transition.     

Studies on the energy levels of153Eu following the β−-decay of153Sm

The level scheme of¹⁵³Eu was investigated by observing the gamma-rays following theβ ^?-decay of the 47 h¹⁵³Sm using a high purity Ge(HPGe) detector and a Ge(Li)-Nal(Tl) fast-slow coincidence spectrometer. The energies and relative intensities of about fifty six gamma-ray transitions were determined. Five of them at energies of 124.91, 431.65, 443.24, 487.75 and 623.73 keV were observed and confirmed for the first time in the present singles and/or gamma-gamma coincidence measurements. These new transitions could be fitted into a proposed level scheme of¹⁵³Eu. Theβ ^?-decay branching ratios as well as the log (ft) values were obtained.     

Experimental evidence for the emission of high-energy gamma-rays from the dinuclear system formed at the first stage of the fusion reactionsnatSn+20Ne (164, 196 MeV)

In the^natSn+²⁰Ne (164,196 MeV) reactions gamma-ray spectra were observed in coincidence with fast alpha particles forward peaked and with those evaporated into a backward hemisphere. The observed differences in the form of the gamma-ray spectra and in the corresponding yields of high-energy gamma-rays are preliminary related to the time evolution of the deformation of the nuclear systems formed in the heavy ion induced fusion reaction.     

Experimental study of the decay of53V

The decay of⁵³V was investigated with a Ge(Li) spectrometer and gamma-gamma coincidence methods. Accurate energy, intensity and half-life determinations of 7 gamma-rays have been performed. These gamma-rays fit in a level scheme with levels at 563.6, 1006.0, 1289.1 and 1536 keV.     

The decay of the 23min131Sb

The direct and the coincidence spectra of gamma-rays from the¹³¹Sb decay have been measured by means of different Ge(Li) detectors. The Sb sources have been prepared from mixture of²³⁵U thermal neutron fission products. The proposed level scheme of the¹³¹Te nuclei is based on the coincidence measurements, the analysis of the energy sums and the reaction data. The 49 of the total number of 64 gamma-rays observed have been placed in the present decay scheme. Properties of the some levels in¹³¹Te are compared with those observed in other oddmass Te isotopes. A probable structure of some of the excited states in¹³¹Te is discussed.     

A high-resolution spectroscopic study of the gamma radiation from the decay of96Nb

The decay of 24h⁹⁶Nb has been studied with a Ge(Li) spectrometer and with a Ge(Li)-NaI(Tl) coincidence spectrometer. A total of 27 gamma-ray transitions were observed, their energies and intensities measured. All but one of these have been incorporated into the level scheme of⁹⁶Mo. The level at 1,625.9 keV reported recently in (n _th, γ) work on⁹⁵Nb has also been observed through the decay of⁹⁶Nb. No experimental evidence has been found for previously proposed levels at 2,657 and 2,791 keV in⁹⁶Mo.     

Spurenanalyse von Cu in ZnS-Phosphoren mittels Neutronenaktivierung

The half life of the 206 kev state of Re¹⁸⁷ was determined with delayed coincidence technic to be:T _1/2=(5·70±0·05)·10^?7 s. The rotation of the spin of the 206 kev state in a magnetic field has been observed in a differential angular correlation measurement with the 480 kev?72 kevγ?γ cascade. From the observed Larmor frequency a magnetic moment ofμ=(5·02±0·06)μ _K for the 206 kev level has been derived. The 480 kev?72 kevγ?γ angular correlation was found to be undisturbed in an aqueous solution of ammoniumtungstate.     

Gamma-ray multiplicity measurements in the28Si+64Ni reaction at 163.8 MeV

The²⁸Si+⁶⁴Ni reaction at 163.8 MeV incident energy is studied by measuring in coincidenceγ-rays and charged particles identified from Z=2 to Z=16. The transition from quasi-elastic to more damped reactions is observed when the difference between the detected charge and the projectile one is increased. The strong influence of the particle decay on the measuredγ-ray multiplicity is evidenced with the help of the statistical model computer code CASCADE. Dissipative events are well described in the rolling limit with excitation energy equally shared between the fragments. The overall agreement is lost for the fragments with the projectile charge which show a small value of theγ-multiplicity even for dissipative events. This is probably connected with the previously observed non statistical behavior of gamma rays emitted in coincidence with projectile-like fragments. In the alpha-spectrum measured in coincidence with gamma-rays, the deexcitation of fused systems is clearly separated from in flight emission of deep inelastic fragments. The low measured gamma-ray multiplicity for fusion events is qualitatively explained taking into account the effect of alpha-emission in the statistical decay.     

Levels in172Yb from the172Lu β-decay

The single and coincidence gamma-ray spectra from the decay of¹⁷²Hf and¹⁷²Lu isotopes have bsen studied using various Ge(Li) detectors. The precise energies and intensities of gammarays have been obtained. Six weak transitions have been observed for the first time and some of transitions reported previously have not been confirmed. The structure of the¹⁷²Yb excited levels is discussed in terms of the unified model.We want to thank Dr. J.Adam, the head of Nuclear Spsctroscopy Department of our Institute, for his continuous support.     

Der Zerfall des163Tb

The beta and gamma radiations of¹⁶³Tb have been investigated employing scintillation and semiconductor spectrometers and coincidence techniques. The sources were produced by the¹⁶³Dy(n,p)¹⁶³Tb reaction. A half-life of 19.5 min has been measured without evidence for an isomeric state in the half-life range of 2 sec to 7 d; especially a 6.5 h activity previously assigned to¹⁶³Tb could not be confirmed. 76 of the total of 82 gamma-ray transitions, representing 99.6% of the gamma-ray intensity, could be assigned to 23 levels in¹⁶³Dy. From beta and beta-gamma coincidence measurements aQβ-value of 1.7 ± 0.1 MeV has been determined. Spin and parity of 3/2⁺ are deduced for the ground state of¹⁶³Tb with the Nilsson configuration [411↑]. The level at 884 keV is interpreted as aJ ^π=1/2⁺ state with a high contribution of the three-quasiparticle configurationp[411↑]-p[523↑]-n[523↓] because of an allowed unhindered beta-ray transition to this level.