The decay of111gPd and111mPd

The decays of 23·4 min^111gPd and 5·5 h^111mPd have been studied using high-resolution Ge(Li) singles -ray spectrometers and Ge(Li)-Ge(Li) coincidence system. About 140-rays were observed in the decays of both isomers. The half-life of^111gPd was remeasured and found to be 23·4±0·2 min. The¹¹¹Ag level scheme and the decay scheme of daughter 74 s^111mAg were examined.Authors are indebted to Prof. I.Úlehla and Dr. J.Adam for permanent support in this work and some usefull comments and to Drs. J.Frána and J.Jursík for preparing of computer programs and help in arrangement of experimental apparatus.     

Gamma-ray investigation of different silver isotope decay

The investigation of different silver isotope decay gamma-rays fromA=102 toA=113 was made using two Ge(Li) detectors with resolution 3·7–6 keV. The results obtained and data from other papers were analyzed to correct and to complete the decay schemes of these nuclei. The radioactivity having a half-time of 3 min. is considered as a new isotope of⁹⁷Ag. Three new states were added to the level scheme of¹⁰²Ag in agreement with the results of the -gamma and gamma-gamma coincidences. Two gamma-ray transitions were added to the scheme of excited levels of¹⁰³Pd. About 60 transitions were found in the decay of the two known isomers of¹⁰⁴Ag. Most of them are located in the decay scheme of the 19 excited levels of the¹⁰⁴Pd isotope. Positive parity was assigned to all of them.The¹¹²Ag and¹¹³Ag gamma-ray spectra were first obtained with the aid of a Ge(Li) spectrometer. The observed transitions were placed in a decay scheme containing 16 levels in the case of¹¹²Cd and 5 levels in the case of¹¹³Cd.The properties of the low excited even-even isotope states of Ru, Pd and Cd are discussed and compared.The authors are deeply indebted to M. K. Nikitin for participation in the chemical separation of a series of samples and to L. F. Protasova for help in the measurements. One of the authors (E.P.G.) expresses his sincere thanks to Prof. V. Petrílka for kindly providing him with excellent conditions for research in Prague.     

Levels in161Tb excited in the decay of 3·6 min161Gd

The decay of¹⁶¹Gd has been studied using Ge(Li) detectors. The single and coincidence gamma-ray spectra were measured. In comparison with the previous studies more precise gammaray energies and relative intensities are reported. Five formerly unreported weak transitions at 97·0, 152·0, 168·0, 346·0 and 417·0 keV have been assigned to the¹⁶¹Gd decay. The properties of excited levels in the¹⁶¹Tb nuclei are discussed in terms of the collective nuclear model. The effect of the Coriolis coupling has been considered.We wish to thank Dr. J.Jursik for his help during the course of experiment.     

Nuclear magnetic resonance of brute force oriented110mAgAg

NMR on brute force oriented nuclei (NMRON/BF) has been observed for^110mAg in elemental silver. Resonances have been measured at approximately 7 T and 8 T with the resulting gradient of 4.583(5) MHzT⁻¹ which produces a value for the^110mAg moment of μ=3.589(4) nm (uncorrected). Factors pertinent to successful NMRON/BF in systems such as^110mAgAg, with a complex decay scheme and modestg-factor, are also discussed.     

The decay of109gPd

The decay of 13·5 h^109gPd has been investigated using high resolution Ge(Li) singles -ray spectrometers and Ge(Li)-Ge(Li) coincidence technique. A total of 31 -rays of^109gPd was observed. The experimental K-conversion coefficients for 19 -transitions were determined. Detailed quantitative information on - coincidences was obtained. The decay scheme of^109gPd is presented.Authors wish to express thanks to Ing. A.Kuklík for the assistance in experimental apparatus arrangement and to Dr. J.Frána for providing of computer programs. Prof. I.Úlehla and Dr. J.Adam are acknowledged for usefull comments.     

Conversion electrons in the decay of191Os

Internal conversion electrons in the decay of¹⁹¹Os have been measured with a 30 cm double focusing spectrometer. The transition energies of (129.27±0·07) keV, 82.5 keV, (46.90±±0.06) keV and (41.76±0.02) keV are given together with the corresponding internal conversion line intensities. It was found that the mixture of the 129 keV transition was 87% M1+13% E2. The previously proposed decay scheme is supplemented by the 46.90 keV transition.The authors would like to thank to M. Vobecký and A. Matalka for preparing the electrodeposited sources.     

Precise measurement of gamma-ray intensities in the decay of 160·9 day isomeric state in177Lu

The precise gamma-ray intensities of the transitions following the decay of 160·9 day isomeric state in¹⁷⁷Lu have been determined from the gamma-ray spectra measured with three different Ge(Li) detectors. The consistency of the obtained data has been verified by the detailed analysis of the intensity balance on the excited levels of the¹⁷⁷Lu and¹⁷⁷Hf nuclei. In order to describe the experimental values of reduced probabilities of E1 transitions connecting the states of 9/2+ +[624] and 7/2-[514] rotational bands in¹⁷⁷Hf, the necessity to introduce the second order corrections to Alaga rules has been established.The author wishes to thank Dr. J. Adam, head of Nuclear Spectroscopy Department of NPI, for his support, Dr. J. Zvolský and Dr. M. Honusek for valuable discussions.     

МЕТОД ОБРАБОТКИ ДВУХ МЕРНЫХ СПЕКТРОВ СОВП АДЕНИЙ И ЕГО ПРИМЕНЕНИЕ К АНА ЛИЗУ γ-γ-СОВПАДЕНИЙ НА Ge(Li)-ДЕТЕКТОРАХ ПРИ РА СПАДЕ155Tb

The method of data processing of two-dimensional coincidence spectra is described and its application for the --coincidence spectra analysis in¹⁵⁵Tb is shown. The existence of levels with energies 86·5; 105·3; 118·0; 235·2; 266·6; 268·6; 286·8; 326·0; 367·7; 427· 4; 451·3; 488·8 keV in¹⁵⁵Gd nucleus is proved on the basis of --coincidences measured in¹⁵⁵Tb decay with Ge(Li)-detectors. Two new transitions with energies of 192 and 163 keV were found.     

Ag110m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Cd¹¹⁰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。     

First experiments on the observation of gamma resonance of a long-lived <Superscript>109<Emphasis Type="Italic">m</Emphasis></Superscript>Ag isomer using a gravitational gamma spectrometer

The first measurements of the resonant Mössbauer self-absorption of the long-lived ^109m Ag isomer gamma rays as a function of the declination angle of the gamma beams from the horizontal direction are presented for a gamma source that represents a single-crystal silver plate doped with a parent ¹⁰⁹Cd nuclide. The resonant absorption is manifested as a minimum of the counting rate ratio of the ^109m Ag and ²⁴¹Am (control gamma source) gamma-line intensities at a zero-declination angle for one of two detectors and an angle of about 1° for another detector. The magnitude of the effect is in agreement with the results of our previous experiments performed on another setup. It follows, from the data obtained, that the angular width of the gamma-resonance profile is less than two degrees, which corresponds to a broadening factor of the Mössbauer gamma line of less than five. The value of this factor calculated from the measured relative magnitude of the ^109m Ag gamma-ray resonant absorption is 6.3 _?1.9 ^+5.2 .     

Observation of the gamma resonance of a long-lived <Superscript>109<Emphasis Type="Italic">m</Emphasis></Superscript>Ag isomer using a gravitational gamma-ray spectrometer

Experiments confirming the previous data on the small real width of the γ resonance of ^109m Ag have been performed with a gravitational gamma-ray spectrometer. The achieved resolution is eight orders of magnitude higher than that of Mössbauer spectrometers using gamma rays from a ⁵⁷Fe nuclide. The theoretically predicted broadening of the Mössbauer gamma line of ^109m Ag by five orders of magnitude (due to the dipole-dipole interaction between the magnetic moments of neighboring nuclei) has not been observed.     

Study ofγ radiation from100Pd decay

This paper presents a study of the rays from the electron capture decay of 3.63d ¹⁰⁰Pd. Singles and coincidence measurements provided an accurate determination of-ray intensities and an improved knowledge of the¹⁰⁰Rh level scheme. Experimental evidence supports excitation of levels in¹⁰⁰Rh at 86-, 136- and 154 keV, not previously reported from the decay of¹⁰⁰Pd.On leave from Departamento de Fisica, Comision Nacional de Energia Atomica, Buenos Aires, Argentina     

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.     

Gamma-radiation in the183Re decay

The gamma-ray intensities have been determined by means of Ge(Li) detectors. The previously proposed decay scheme has been tested using Ge(Li)- spectrometers. It has been found that the experimental data are not in disagreement with foregoing decay scheme. The comparison of the theoretical (if the Coriolis interaction is taken into account) and experimental gamma line intensity ratios is given.     

Study of122Te(n, γ)123 Te reaction

-rays emitted after thermal neutron capture in¹²²Te have been investigated for the first time. Energies and intensities of 80 transitions assigned to¹²³Te have been determined. Fortyeight of these transitions have been placed in the¹²³Te level scheme among 27 excited levels. Two new levels of 1808·8 and 2092·3 keV,J=(1/2, 3/2), have been observed. The neutron binding energy has been found to be 6929·1±0·5 keV. The role of direct capture mechanism has been examined.     

Nuclear orientation study of the decay of204BiFe

The decay of²⁰⁴Bi nuclei (I =6⁺, T_1/2=11·22 h) oriented in an iron host was investigated on the JINR low-temperature nuclear orientation facility SPIN. The orientation parameterB ₂=1·17 (6) was obtained from the analysis of six prominent E1 gamma-transitions. From the measured normalized intensities of the gamma-rays observed some 70 values of multipole mixing ratios for the gamma-transitions in²⁰⁴Pb nucleus were determined for the first time. The spins 6, 6, 5 and 4 could be uniquely assigned to the²⁰⁴Pb negative parity levels at 3891·5 keV, 3768·4 keV, 3301·5 keV and 2338·2 keV, respectively. The spin-parity assignments of the levels at 4183·8 keV, 4094·2 keV, 3782·0 keV, 2506·9 keV and 2065·1 keV were confirmed as 6^–, 6^–, 5^–, 5^– and 5⁺, respectively. For the level at 3105·1 keV spin-parity 5^– was suggested and spinparity 7^– of the level at 2696·4 keV was called in question. The possible placements of the gammatransitions 3 1351·7 keV and 1353·4 keV in the decay scheme is discussed. The reorientation parameters for the long-living levels at 2264·2 keV (T _1/2=0·45 s) and 1273·9 keV (T _1/2= =265 ns) were determined asG ₂=0·41 (14) andG ₂=0·60 (17), respectively. For the isomeric level at 2185·7 keV (T _1/2=67·2 min) the value ofG ₂=0·88 (49) was proposed.The authors would like to express their thanks to T. I. Kracíková and M. Trhlík for the valuable discussions in the course of the evaluation of the experimental data.     

Beta decay of very neutron-rich110Mo studied at the new IGISOL facility

The decay of the new activity¹¹⁰Mo (t_1/2=0.30(4).s) has been observed at the new IGISOL separator. Multiscaled singles,--t and -y-t coincidences were recorded. The decay scheme suggests I=2⁺ for the ground state of the daughter nucleus¹¹⁰Tc. Three 1⁺ levels are fed with logft values below 5, indicating no drastic change among Mo and Ru decays at the middle of the neutron shell. This experiment confirms the expectation that the new IGISOL facility will allow the identification of one or two new more neutron-rich isotopes per element in this region.Supported by the Academy of Finland.     

Concerning internal conversion coefficients in Hf180

The gamma-ray relative intensities from transitions in Hf¹⁸⁰ following the 5.5 hour Hf^180m decay have been measured using a bent-crystal gamma-ray diffraction monochromator and a least-squares fitting technique. From these measurements it was possible to deduce a value for the internal conversion coefficient for the 93.3-keV transition of α _T ⁹³ =4.91±0.23. From previous measurements of conversion electron intensities byEdwards andBoehm and our gamma-ray relative intensities, internal conversion coefficients for all transitions except the 57.5-keV transition were obtained. These coefficients agree well with the previous determinations byEdwards andBoehm, however, our measurements have improved precision, particularly in the case of 501.3-keV transition. The present measurements of α _K for the 215.3-, 332.5-and 443.8-keVE2 transitions are 11% lower than theoretical values while α_K for 93.3 keV E2 transition agrees closely with the theoretical value. These results are in close agreement with the previous measurements ofEdwards andBoehm. The present experimental α_K for the 501-keV transition agrees closely with the theoretical α_K for an E3 multipolarity.     

Measurement of the nuclear magnetic moment of110Ag(T 1/2=24.4 s)

Nuclear magnetic resonance of¹¹⁰Ag has been observed in silver halides using the polarized neutron capture,β decay anisotropy method. The magnetic moment was determined asμ _I(¹¹⁰Ag)=2.7084 (5) nm (uncorrected).     

Evaporation residue cross sections in complete fusion reactions between52Cr-56Fe,63Cu-Ni and63Cu-Ag

Evaporation residue cross sections have been measured by the technique of the telescopeE ·E counter at very small angles. The angular distribution has been followed down to 2°15, and rather precise values were obtained for that fraction of the compound nucleus decay after complete fusion for the systems⁶³Cu+Ni,⁶³Cu+Ag and⁵²Cr+⁵⁶Fe at two bombarding energies. A comparison has been done with evaporation calculations using the code ALICE, and the rotating liquid drop concept. It is shown that a large discrepancy occurs at low energy for these heavy projectiles. The origin of this difference is discussed.