Investigation of the decay rate for71Ge in chemical compounds and calibration of the Mössbauer isomer shift of the 67 keV γ-transition of73Ge

Changes of the radioactive decay rate of⁷¹Ge (T _1/2=11.43 days) have been studied experimentally for⁷¹Ge in some compounds of bivalent and quadrivalent germanium. Relative changes Δλ/λ of the electron capture probability have been measured, and the chemical changes Δρ(0) of the electron density at the germanium nuclei have been determined from these measurements. Values for the Mössbauer isomer shift calibration constants for the 67 keV γ-transition of⁷³Ge have been estimated:C=δ/Δρ(0)=(0.061±0.020) mm·s^?1/a.u., Δ〈r ²〉=(21±7)·10^?3 fm², ΔR/R=(6.9±2.3)·10^?4.     

Investigation of dual decay of70Ga (21 min)

The weakβ ^?-branchings in⁷⁰Ga decay leading to excited states in⁷⁰Ge at 1039 keV, and 1215 keV were measured byβ ^?-ray and γ-ray detection in 4π geometry to be 0.36 ±0.02%, and 0.32±0.01%, respectively. The weak electron capture decay of⁷⁰Ga was confirmed and its intensity measured to be 0.41±0.05%. The energy of the γ-rays was remeasured to be 176.17±0.02 keV, and 1039.20±0.08 keV.     

The decay of75Ga to levels in75Ge

The decay of⁷⁵Ga has been investigated with Ge(Li) spectrometers. Energy and intensity determinations for 37 gamma rays have been performed. A level scheme for⁷⁵Ge was deduced, where 31 gamma transitions could be placed. Beta branch intensities were estimated from the measured gamma intensities. Spin and parity assignments for most of the levels were made in agreement with reaction and neutron capture studies. Half life of⁷⁵Ga was measured to be (130±6) sec and that of the 139.3 keV isomeric state in⁷⁵Ge to be (47.7±0.5) sec.     

On the decay of73Ga to levels in73Ge

Theγ-radiation following the β^? decay of⁷³Ga has been studied. Singlesγ andγγ coincidence spectra were recorded with Ge(Li)-detectors. 17γ-rays were assigned to transitions in⁷³Ge, where 11 excited levels are proposed. From logft values based onγ-transition intensities, spin and parity assignments for the levels were deduced. The half-life of⁷³Ga was measured to (4.86±0.03) h. From allowedβ-transitions the ground state of⁷³Ga was assigned 3/2^?.     

Cross sections and γ-rays from multiple neutron capture in151Eu

Primary capture gamma rays following multiple neutron capture in¹⁵¹Eu have been measured as a function of the irradiation time. Neutron capture cross sections of the¹⁵²Eu 3^? groundstate and of the¹⁵²Eu 0^? isomer (T _1/2=9.3h) were determined. These cross sections are relevant for the interpretation of inelastic scattering of neutrons at isomeric states with energy gain (neutron acceleration). The level scheme of¹⁵³Eu has been extended. Neutron binding energies of¹⁵²Eu,¹⁵³Eu,¹⁵³Gd and¹⁵⁴Gd are given.     

Zeitliches Abklingen und Anisotropie von p-Terphenyl- undp-Terphenyl-Anthrazen-Mischkristallen bei Beschuß mit α-Teilchen

The time dependence of scintillation intensity from single crystals ofp-terphenyl and mixed crystals ofp-terphenyl and anthracene after bombarding with α-particles was investigated at the two temperaturesT=296 °K andT=92 °K. For the crystals ofp-terphenyl the time dependence of the scintillation anisotropy was also measured. Using the formulas given byKing andVoltz the decay curves ofp-terphenyl were decomposed into two components. Good agreement between experiment and theory was found. The ratio of the prompt intensity to the delayed intensity was determined to be 1∶2 atT=296 °K and 1∶3 atT=92 °K. The diffusion constants for triplet excitons were calculated to beD _T(296 °K)≈10^?5 cm² sec^?1 andD _T(92 °K)≈ 2×10^?6 cm² sec^?1, and the triplet-triplet interaction rate constantsχ _tt(296 °K)≈ 2.5×10^?11 cm³ sec^?1 andχ _tt(92 °K)≈0.5×10^?11 cm³ sec^?1.     

The decay of45Ti to45Sc

The low intensity β⁺/E.C. branches in the decay of⁴⁵Ti to excited states of⁴⁵Sc have been reinvestigated in order to resolve discrepancies in reported branching ratios. A new branch to the 974 keV level, having an intensity of 9.9±1.2×10^?5/decay has been found. A previously reported branch to the 1237 keV level was found to be in error. The intensities for decay to the levels at 720, 1408 and 1661 keV levels were determined to be 154±12, 90.2±9.7 and 52.5±5.6, respectively, in units of 10^?5 per decay.     

Synthesis of Ge-Sn at high pressure and high temperature in a laser-heated diamond anvil cell

Ge–Sn compound is predicted to be a direct band gap semiconductor with a tunable band gap. However, the bulk synthesis of this material by conventional methods at ambient pressure is unsuccessful due to the poor solubility of Sn in Ge. We report the successful synthesis of Ge–Sn in a laser-heated diamond anvil cell (LHDAC) at ~7.6 GPa &; ~2000 K. In situ Raman spectroscopy of the sample showed, apart from the characteristic Raman modes of Ge TO (Г) and β-Sn TO (Г), two additional Raman modes at ~225 cm^?1 (named Ge–Sn₁) and ~133 cm^?1 (named Ge–Sn₂). When the sample was quenched, the Ge–Sn₁ mode remained stable at ~215 cm^?1, whereas the Ge–Sn₂ mode had diminished in intensity. Comparing the Ge–Sn Raman mode at ~225 cm^?1 with the one observed in thin film studies, we interpret that the observed phonon mode may be formed due to Sn-rich Ge–Sn system. The additional Raman mode seen at ~133 cm^?1 suggested the formation of low symmetry phase under high P–T conditions. The results are compared with Ge–Si binary system.     

A study on the decay of81As

The decay of⁸¹As was investigated with Ge(Li) spectrometers. Accurate energy and intensity determinations for 29 gamma rays have been performed, from which a level scheme was deduced for⁸¹Se. Beta component intensities were obtained from the measured gamma intensities. Spin and parity assignments for most of the levels were made in agreement with the reaction and neutron capture studies. The half life of⁸¹As is measured to be (35.8±1.6) sec. Shell model calculations as well as unified model calculations have been performed in order to study the level scheme of⁸¹Se.     

Decay of the134Cs isomers and the levels of134Xe,134Cs,and134Ba

A precision study of the decay of¹³⁴Cs ^g and¹³⁴Cs ^m has been made, using ordinary Ge(Li) spectrometers and ā Compton-suppression spectrometer. The logft value of the second forbidden nonuniqueβ-decay to¹³⁴Xe has been measured to be 13.0±0.2. TheM4γ-ray transition in¹³⁴Cs^m(8^?) decay has been measured to haveα _K= 73±7 and a hindrance of 7.0 over the Moskowski estimate. This is discussed in terms of the level configurations and the analogous transition in¹³³Xe. A new intensity limit of 2×10^?6 has been set for the zero-phonon transition between the 4⁺ and 2⁺ members of the two-phonon triplet. This leads to an upper limit forB(E2)_4→2′, greater than 905. This and the more preciseγ-ray intensity values are discussed in relation to presently available nuclear models.     

K-capture probability in the decay of139Ce(137.5d)

The K-capture probability (P _K) in the decay of¹³⁹Ce (137.5d) has been determined from the analysis of the K x-ray gamma ray sum-peak observed with a Ge (Li) x-ray detector. Furthermore,P _K is estimated independently from the measurement of the K x-ray intensity in the decay, using the known conversion coefficients of the 165.8 keV transition. Using the weighted average ofP _K measured as above, the mass difference between¹³⁹Ce and¹³⁹La is found to be 273 _?13 ⁺²¹ keV.     

Note on the decay of200Au

Gamma and beta rays from the decay of²⁰⁰Au (48.4 min) were studied employing Ge(Li) and plastic detectors in various singles and coincidence arrangements. The intensity of the β-branch to the ground state of²⁰⁰Hg was determined as 79%, and the disintegration energy of²⁰⁰Au to be asQ _β=2.26 ± 0.06 MeV. A tentative spin and parity assignment of (1,2)⁺ is proposed for levels at 1515.2 and 1972.5 keV in 200_Hg     

Decay of 8.0-day131I to levels of131Xe and 11.77-day131mXe

The decay characteristics of¹³¹I have been determined with high accuracy. The total branch from¹³¹I to^131mXe has been measured to be 1.086±0.007%. The half life of^131mXe has been measured as 11.770±0.012 days. Theγ-ray spectrum has been determined and new transitions at 85.92, 232.17, 295.83, 302.44, and 449.57 keV established. The position, spin and parity were established for a 9/2^? level at 341.140 keV and spin and parity of 7/2^? established for a level at 666.921 keV. The log f₁t for the unique firstforbiddenβ transition from 7/2^{+ 131}I to 11/2^{? 131m}Xe has been calculated to be 9.78.     

Levels in189Os populated in the decay of189Re

The excited level scheme of¹⁸⁹Os as populated by the decay of 23.4-h¹⁸⁹Re has been studied by use of Ge(Li) and Si(Li) detectors in the γ-ray singles and coincidence mode. The data confirm the presence of excited levels in¹⁸⁹Os at 30.8 (J ^π=9/2^?), 36.2 (1/2^?), 69.5 (5/2^?), 95.2 (3/2^?), 216.7 (7/2^?), 219.4 (7/2^?), 233.6 (3/2^?), 275.8 (5/2^?), 496.8 (1/2^?, 3/2⁺) and 599.8 (1/2^?, 3/2⁺) keV. The spin and parity assignments are based on multipolarities determined by internal conversion coefficient measurements and decay systematics. A decay scheme is established for¹⁸⁹Re which accommodates 98% of the electromagnetic transition intensity. No evidence for the 150-d¹⁸⁹Re isomer was found in this study.     

Energy levels of174Yb populated in the decay of174Tm

The decay of the¹⁷⁴Tm activity has been studied with Ge(Li) detectors and with a Ge(Li)—NaI(Tl) coincidence arrangement. Gamma ray energies and relative intensities were determined. Five new gamma transitions are reported, four of which have been placed in the decay scheme in addition to the previously observed but unplaced 1305 keV transition. Five energy levels at 1557.7, 1762.1, 1781.1, 1877.5 and 2050.1 keV not earlier reported to be populated in the decay of¹⁷⁴Tm are suggested. Some spin and parity assignments are proposed and the intrinsic structure of several states is discussed in terms of two quasi-particle excitations. For the half-life of¹⁷⁴Tm a value 5.4±0.1 min was measured.     

Some investigations on the decay of60Co

The⁶⁰Co decay has been reinvestigated using an electromagneticβ-spectrometer and a Ge(Li)γ-spectrometer. A new weakβ ^?-transition of characterΔJ=3, no parity change between the 5⁺ groundstate of⁶⁰Co and the second excited 2⁺ level atE=2.155 MeV in⁶⁰Ni could be established. The endpoint energies and intensities of the threeβ ^?-transitions are: $$\begin{gathered} E_{\beta \bar 1\max } = \left( {1.492 \pm 0.020} \right)MeV,I_{\beta \bar 1} = \left( {0.08 \pm 0.02} \right)\% ; \hfill \\ E_{\beta \bar 2\max } = \left( {0.670 \pm 0.020} \right)MeV,I_{\beta \bar 2} = \left( {0.18 \pm 0.03} \right)\% ; \hfill \\ E_{\beta \bar 3\max } = \left( {0.315 \pm 0.004} \right)MeV,I_{\beta \bar 3} = \left( {99.74 \pm 0.05} \right)\% ; \hfill \\ \end{gathered} $$ . The intensity ratio of the stopover and crossoverγ-transitions deexciting the 2.155 MeV level has been determined to be ≧120. Some conclusions for the theory are discussed.     

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.     

In-beam gamma-ray and electron spectroscopy following the75As(p,n)75Se reaction

The level scheme of⁷⁵Se has been studied through the⁷⁵As (p, n) reaction at proton energies from 1.5 to 5.0 MeV.γ-ray and internal conversion electron measurements were made using NaI (T1) and Ge(Li) detectors and a six-gap electron spectrometer. A proportional counter and a thin window NaI(T1) detector were used to detectγ-rays with energies less than 30 keV. The level scheme has been established by observing the thresholds of variousγ-rays and byγ-γ and e^?-γ coincidence measurements. New levels at 133.0, 293.2, 790.0, 953.0, 1020.8, 1184.3, 1198.5 and 1258.2 keV not observed in earlier (p, n) studies have been established. Conversion coefficients of most of the low-lying transitions have been determined. Angular distributions of some of theγ-rays were also measured and compared with the statistical model calculations. DefiniteJ ^π assignments have been made to most of the low-lying levels. Life-times of the 112.1, 133.0, 286.7 and 293.2 keV levels have been measured to be 0.69±0.12, 5.3±0.6, 1.35±0.15 and 31±2 nsec respectively. The reduced transition probabilities for various low-lying transitions have been determined and compared with recent calculations. The 1/2^? and 9/2⁺ levels hitherto unknown in this nucleus has been identified. The structure of the low-lying levels is discussed in terms of the existing models.     

Über die selbständige Polarisierung des Spins der Elektronen durch Ausstrahlung bei der Bewegung auf einer Spiralbahn im Magnetfeld

The nuclear half-life of the 287 keV second excited state of⁷⁵Se, populated by the reaction⁷⁵As(p, n)⁷⁵Se^* has been measured by the delayed coincidence technique. NaJ(Tl)- and Ge(Li)-detectors were used for measuringγ-energies and time-spectra. By slope analysis of the time-spectra we obtained a half-life of T_1/2(⁷⁵Se, 287 keV)=(30.0±0.4) ns. Possible spin assignments for the 287 keV state in⁷⁵Se from logft-values derived fromβ ⁺-decay data of⁷⁵Br to this level byBaskova et al are 3/2^? and 1/2^?. Application of an external magnetic field of 24 kG to the target nuclei yielded no measurable perturbation of the time-spectra, thus a spin value of 1/2^? for this level seems to be more probable.