Der Zerfall des Rh102g,Rh102m und Tc102m

The decays of the 206 day-Rh^102g , 2.9 year-Rh^102m and 4.35 min-Tc¹⁰² m have been investigated using several sizes of Ge(Li)-counters. From the analysis of gamma spectra from several Rh¹⁰²-sources, measured over a period of 2.2 years, the gamma rays associated with each activity were identified. Energies and relative gamma intensities of 71 transitions have been determined. 22 transitions are assigned to the decay of 206 day-Rh^102g , 16 to 2.9 year-Rh¹⁰² and 33, twenty five unreported, to 4.35 min-Tc^102m . All except one transition are placed in a level scheme of Ru¹⁰².     

Die γ-Spektren von Tc95, Tc95m und Tc96

Theγ spectra of Tc⁹⁵ (20 h), Tc^95m (62 d), and Tc⁹⁶ (4.3 d) have been investigated using Li-drifted germanium counters. The observedγ transitions in the decay of Tc⁹⁵ and Tc^95m are in agreement with earlier investigations except for 6 transitions at 204, 680, and 840 keV in Tc⁹⁵ and at 970, 1390, and 1630 keV in Tc^95m reported previously which have not been confirmed. In the spectrum of Tc⁹⁶ new transitions at 437, 462, 1094, 1200, and 1505 keV have been identified. The level scheme of Mo⁹⁶ is discussed in respect of these results.     

Der Zerfall des Ag106g und Ag106m

The decays of the 25 min-Ag^106g and 8.3 d-Ag^106m have been investigated using Ge(Li)- and Si(Li)-counters. Theγ-rays of 17 transitions in the Ag^106g -decay and of 42 transitions in the Ag^106m -decay have been observed and their energies and relative intensities have been determined. The intensities of theseγ-rays and the intensities of conversion-electrons known from earlier measurements allow the determination ofK-conversion-coefficients for 23 transitions. The present data are consistent with a level-scheme of Pd¹⁰⁶ having states at 0, 0⁺; 511.8, 2⁺; 1127.8, 2⁺; 1133.1, 0⁺; 1228.8, 4⁺; 1557.4, 3⁺; 1562, 2⁺; 1702.8, 4⁺; 1931.7, 3, 4⁺; 2002, 0⁺; 2040.4, 3, 4⁺; 2076.8, 3, 4⁺; 2084.2, 3^?; 2305.7, 4^?; 2324, 1, 2⁺; 2350.4, 3, 4⁺; 2365.3, 3, 4⁺; 2529, 1, 2⁺; 2756.3, 5⁺; 2951.3 keV, 5⁺. The level-scheme of Pd¹⁰⁶ is compared with the predictions of the vibrational model for spherical nuclei.     

Der Zerfall des Fe53g und des Fe53m

Theγ-ray spectra from the decays of 8.5 min-Fe^53g and a new (2.51±0.02) min-Fe^53m have been investigated by means of Ge(Li)-detectors. As far as the Fe^53g -decay is concerned no other but the known 380 keV-transition (43%) has been observed indicating that the proceedingΒ ⁺-decay leads to the groundstate and first excited state of Mn⁵³ only. This contradicts formerΒ ⁺-spectroscopic results but is consistent with recent spin assignments. In the Fe^53m -decay fourγ-transitions have been found: 701 keV (100%), 1011 keV (76%), 1328 keV (76%), and 2339 keV (24%). The proposed level scheme of Fe⁵³: 0 keV (7/2^?), 1328 keV (9/2^?), 2339 keV (11/2^?), and 3040 keV (19/2^?, 2.5 min) is in agreement with results published recently byEskola. The level schemes of Mn⁵³ and Fe⁵³ are discussed in terms of the individual particle shell model.     

Der Zerfall des125m Xe,des127m Xe und des127g Xe

The decay of^125m Xe produced by the reaction¹²²Te(α, n)^125m Xe using a target enriched in¹²²Te (95.4%) and the decay of^127m Xe produced by the reaction¹²⁷J(d, 2n)^127m Xe have been investigated: ^125m Xe decays with a half-life ofT _1/2=(56±3) sec by ayy- cascade withE _γ1=(140.4 ±0.5) keV andE _γ2=(110.5 ±0.5) keV. The experimental conversion coefficients yield multipolarities ofE3 for the 140.4 keV isomeric transition and predominantlyM1 for the 110.5 keV-transition. ^127m Xe decays with a half-life ofT _1/2=(71±2) sec. The decay also proceeds by aγγ-cascade with an isomeric E3 transition ofE _γ1=(172.5±0.3) keV and a predominantlyM1 transition ofE _γ2=(124.6±0.3) keV. In the decay of^127g Xe an additional branching of the electron capture to a level at (618.1±0.3) keV was observed. The relative probability forK-captureP _K618/P_K375=0.40 ±0.07 yields a total transition energyQ _EC=(664 ±4)keV. A spin of 1/2⁺ was assigned to the ground state.     

Der Zerfall von Nb94 m

Using scintillation spectrometers and coincidence techniques the decay of Nb^{94 m} has been investigated. TheK-shell conversion coefficient of the 41.5 keV isomeric transition was found to be 570±100 indicating aM 3 transition. The maximum energy of theβ-decay to the 0.87 MeV level of Mo⁹⁴ is (1.15±0.03) MeV occurring (4·5±0·7)×10^?3 per disintegration, anotherβ-decay to the 1.57 MeV level was found to be (4·0±1·3)×10^?5. From this the parities and spins of the levels involved in the decay of Nb^{94 m} are determined.     

Der Zerfall Co58m →Co58g

Co^58m , Co^58g and Co⁵⁵ were obtained by radiating nickel-foiles with deuterons of energies 11,5 MeV and 2,07 MeV. The γ-radiation was measured with NaJ scintillation spectrometers. For the isomeric transition of Co^58m was determinedT _1/2=(9.15±0.1)h,T _γ=(25±1)keV,α _K=2200±300 and α_L+M=1100±300. From these values it follows, that the radiation is ofM3-type. Twoγ-energies of 95 keV and 1322 keV were found belonging to Co⁵⁵.     

The beta decay of90g Tc and90m Tc

The level structure of⁹⁰Mo is investigated via the beta decay of^90g Tc and^90m Tc whose half-lives are measured to be 8.7±0.2 and 49.2±0.4 s, respectively. The decay properties are studied by means of beta and gamma spectroscopy techniques. The level structure of⁹⁰Mo populated in the decays of both isomers is proposed with deducedJ ^π values. Theβ-decay energies for^90g Tc and^90m Tc are 8.8±0.3 and 9.3±0.3 MeV, respectively. The structure is discussed in terms of the shell model.     

The decay of93g Ru,93m Ru,91g Mo,91m Mo,91g Tc and91m Tc

Decay studies on a number of short-lived odd nuclei in theN=50 region are described. The 59.6-s ⁹³Ru ground state decay was studied in detail for the first time; in these experiments the 10.8-s activity^93m Ru was discovered. The⁹¹Tc activities were also observed for the first time. The ground state and an isomeric state of this nucleus decay with nearby equal half-lives (3.14 and 3.3-min). The activities^91g Mo (16.6-min) and^95m Mo (65.1-s) have been reinvestigated. A number ofγ-rays, previously erroneously assigned to the⁹¹Mo activities, could be eliminated. A strong similarity is noted for the decay schemes of theN=49 isotones^91m Mo and^93m Ru. The energy of the 1/2^? isomeric state in⁹³Ru and theB(M4)-value of the isomeric transition fit well into the systematics of the previously knownN=49 isotones.     

Konversionskoeffizienten und Fluoreszenzausbeuten beim Zerfall des Ir192m und Co58m

With a proportionalcounter and an anthracene-crystal-spectrometer theL-X-ray- and the conversion-electron-spectra of \(Ir^{192_{m_1 } } \) were measured. TheL-fluorescenceyield of iridium was found to beω _L=0.30±0.04. The partial fluorescence-yields of theL ₂- andL ₃-subshells could be determined:ω _L2 =0.35±0.14 andω _L3 =0.29±0.04. The conversion-coefficients for the isomeric transition of \(Ir^{192_{m_1 } } \) were also measured:α _L =1660±250 andα _L +α _M =2030±230. The spectra of the conversion-electrons of the 25 keV-isomeric transition of \(Co^{58_m } \) were measured with a methane-filled proportionalcounter, and theγ- and X-rays with a Nal-scintillation-spectrometer. The conversion-coefficients for this transition and theK-fluorescence-yield of cobalt were found to beα _K =2000±260,α _L+M =890±150,K/(L+M)=2.25±0.15,α _K =0.34±0.02.     

Der Zerfall des Co60m und Zr90m

Co^60m was produced by the reaction Co⁵⁹ (n,γ) Co^60m ; its decay has been investigated by scintillation spectrometers. The half-period has been remeasured yielding a value ofT _1/2=(10·35 ±0·20) min. The isomeric decay mainly leads to the Co⁶⁰ ground state by a (58·6±0·6) keV transition. TheK-conversion coefficientα _K= 41±3 and the total conversion coefficientα=47±3 indicate the transition to beM3 and the spin of Co^60m to be 2⁺. Further Co^60m decays by beta transitions to Ni⁶⁰. The beta component (8·6±1·2)·10^?3%, log ft=7·32 leading to a (2·16±0·02) MeV level has been measured for the first time. A second component (0·24±0·03)%, log ft=7·23 leads to the 1·33 MeV level. The 2·16 MeV level decays to the Ni⁶⁰ ground state mainly by a 0·83–1·33 MeV cascade, in a few cases by a direct transition. The spin of the 2·16 MeV level is 2⁺. Zr^90m was produced by the reaction Zr⁹⁰ (n,n′) Zr^90m . The half-period was measured yielding a value ofT _1/2=(0·83±0·03) sec. Zr^90m decays in the following way: (77±5) % by a direct (2·31±0·02) MeV —E 5 transition to the Zr ground state and (23±5)% by a (132·5±1·5) keV-(2·18±0·03) MeV cascade detected for the first time in the isomeric decay. TheK-conversion coefficient of the 132·5 keV transition isα _k=(2·2±0·3) indicating this transition to beE3 and the spin of the 2·18 MeV level to be 2⁺. The Zr^90m -decay sheme is in accordance with the level sequence of Zr⁹⁰ as measured in the Nb⁹⁰ decay.     

Suche nach Zweiquantenprozessen beim Zerfall von Xe131m

The decay of Xe^131m was investigated in order to detect nuclear double decay processes, in which the transition energy is distributed either between twoγ-quanta or between oneγ-quantum and oneK-conversion electron or between twoK-conversion electrons. By analyzing the emittedγ-radiation in a two-dimensional way an upper limit of 2.2 · 10^?5 was derived for the ratio of theγγ- toγ-transition probability. An investigation of theγ-spectrum in coincidence withK-quanta yielded an upper limit of 3 · 10^?2 for the rate ofe _Kγ-transitions relative toγ-transitions. The simultaneous emission of twoK-quanta was actually observed. These doubleK-quanta result either from the doubleK-conversion that was sought or from the internal conversion of the internal Compton-effect. For the doubleK-electron emission toγ-emission probability a value of (3.6±0.7) · 10^?3 was obtained. TheK-conversion coefficient and the half-life of Xe^131m were measured to be 32.1±0.4 and 11.94±0.04 d, respectively.     

Der Zerfall von Tm174 und Tm175

The radioactive isotopes Tm¹⁷⁴ and Tm¹⁷⁵ were produced by the reactions Yb¹⁷⁶ (γ, np) Tm¹⁷⁴ and Yb¹⁷⁶(γ,p) Tm¹⁷⁵ respectively, with bremsstrahlung of 54 MeV maximum energy. TheΒ- andγ-radiations from the decay of these isotopes were investigated using scintillation counters, solid state detectors and coincidence methods. The decay scheme proposed for Tm¹⁷⁴ is similar to those proposed by previous investigations. The spin assignment of the isomeric 1520 keV level was revised to beI=7. The decay of Tm¹⁷⁵, which was until now rather unknown, has a half-life of of 15.2±0.5 min. The suggested decay scheme shows excited levels at 105 (9/2^?), 511 (1/2^?), 553 (3/2^?), 598 (5/2^?), 643 (5/2^?, 7/2^?), 816 (3/2^?), 873, 990, 1454 (1/2⁺), 1496 (3/2⁺), 1505, 1810 and 1881 keV. The results are discussed using the Nilsson model.     

Konversionskoeffizienten und Fluoreszenzausbeuten beim Zerfall des Hg199m

Hg^199m was produced by bombarding natural HgO with fast neutrons. The conversion electrons of the cascade decay were investigated with Si(Li)-counters. By application of the summing technique the conversion coefficients andL-shell fluorescence yields of Hg were determined. The gamma rays were studied with a Ge(Li)-counter. The following results were obtained: half-lifeT _1/2=(42.6± 0.2) min; energies of the transitionsE _γ1=(374.1± 0.1) keV,E _γ1=(158.3± 0.1)keV; intensity ratio of the gamma raysI _γ(158 keV):I _γ(374keV)=(424± 42):100; conversion coefficients α_K158=0.30± 0.03, α_total158=0.94± 0.09, α_K158/α_LM...158=0.47± 0.02, α_L158/α_M...158=3.10± 0.16;α_K374=3.51± 0.28,α_total1374=6.19±0.47,α_K374/α_LM...374=1.32±0.04, α_L374/α_M...374=2.14±0.11;L-shell fluorescence yields \(\bar \omega _L \) =0.40± 0.04, ω_KL=0.41±0.04.     

Der Zerfall von Er171 und Er165

Theγ-spectrum of a neutronactivated probe of natural Er₂O₃ revealed an additional peak at 55 keV, which was attributed to the characteristicK-Röntgenstrahlung from the decay of Er¹⁶⁵ by measurement of its half-life in a NaJ-wellcrystal. The activation cross section for thermal reactor neutrons for Er¹⁶⁴ (n, γ) Er¹⁶⁵ has been determined to σ _A =20±7 barn. The averaged conversion coefficient of the 111, 116 and 124 keV γ-rays from Er¹⁷¹→Tm¹⁷¹ have been remeasured with scintillation counter equipment.     

Der Zerfall des Pt195m und des Au195

The decays of Pt^195m (4.1 d) and Au¹⁹⁵ (192 d) have been investigated with a Ge(Li)-counter and a Ge(Li)-NaJ coincidence circuit. Theγ-spectrum of Pt^195m showed new lines with energies 239.5, 140.7 and 211.1 keV found earlier only in coulomb excitation experiments. Theγ-spectrum of Au¹⁹⁵ established a new level of Pt¹⁹⁵ at 199.8 keV with single particle character. These results led to a modified level scheme and modified reduced transition probabilities for the levels of Pt¹⁹⁵. By comparison of theγ-spectrum of Pt¹⁹⁵ m and Au¹⁹⁵ the ratios of electron capture branches of Au¹⁹⁵→Pt¹⁹⁵ decay have been determined.     

DieK-Fluoreszenzausbeute von Titan und der Zerfall des48Vanadium

TheK-fluorescence yieldΩ _K of Titanium has been measured using the coincidence method and investigating the electron capture decay of⁴⁸V. The detectors used have been a Si(Li)- and a Ge(Li)-detector for the X- andγ-rays. The experimental results areP _K Ω _K =0.2005 ±0.0030 andΩ _K (Ti)=0.224±0.003 usingP _K =0.896. For the branching ratios of the decay of⁴⁸V we obtainedEC (3.239) 7.9±0.6%EC (3.224) 2.9±0.4%EC (2.295) 35.6±2.0% Β⁺ (2.295) 52±1.0% all others 1.6%. Additionally someγ-ray-energies of the decay of⁴⁸V and the half-life,T _{1 2}=(16.23 ±0.03)d, have been measured.     

Suche nach Strahlungsprozessen zweiter Ordnung beim Zerfall von Ag109m

The decay of an excited state by the emission of twoγ-quanta (γ γ-transitions) or two conversion electrons (e e-transitions) or oneγ-quantum and one conversion electron (γ e-transitions) is expected as a second order radiation process. The decay of Ag^109m was examined for such events using a special arrangement of two NaJ-scintillation counters in coincidence. The energies of coincident quanta were displayed on the two axes of an “X-Y”-Oscilloscope respectively. For the ratio ofγ γ-transitions to one-quantum transitions an upper limit of\(\frac{{W_{\gamma \gamma } }}{{W_\gamma }} \leqq 1,9 \cdot 10^{ - 5} \) was obtained. Furthermore theγ-spectrum in coincidence withK X-rays was studied. From these measurementse e- andγ e-transition rates can be calculated for the case ofK shell conversion. The results obtained are:

$$\frac{{W_{^e K^e K} }}{{W_\gamma }} = \left( {8,1_{ - 1,7}^{ + 0,6} } \right) \cdot 10^{ - 3} and\frac{{W_{\gamma ^e K} }}{{W_\gamma }}< 1,5 \cdot 10^{ - 3} .$$     

Der Zerfall des84Rb und die Fluoreszenzausbeute von Krypton

The electron capture decay and the positron decay of⁸⁴Rb were investigated using NaJ (Tl)-detectors and a Ge (Li)-detector. Measurements of all intensities and of some informative double and triple coincidences were performed. From coincidence measurements betweenK-X-radiation and the following γ-radiation we got theK-fluorescence yield of Krypton Ω_itK=0.653 ± 0.004. Taking in consideration former measurements¹ one concludes a continuous behaviour of Ω_itK(Z) forZ=36, 37 and 38 within an uncertainty of 1%. For the branching ratios of the decay of⁸⁴Rb we obtained The half-life of⁸⁴Rb was determined to beT _1/2=(34.5 ± 0.2) d.