D. Gföller

Der Zerfall des125mXe, des127mXe und des127gXe

AbstractThe decay of125mXe produced by the reaction122Te(α, n)125mXe using a target enriched in122Te (95.4%) and the decay of127mXe produced by the reaction127J(d, 2n)127mXe have been investigated: 125mXe decays with a half-life ofT1/2=(56±3) sec by ayy- cascade withEγ1=(140.4 ±0.5) keV andEγ2=(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. 127mXe decays with a half-life ofT1/2=(71±2) sec. The decay also proceeds by aγγ-cascade with an isomeric E3 transition ofEγ1=(172.5±0.3) keV and a predominantlyM1 transition ofEγ2=(124.6±0.3) keV.In the decay of127gXe an additional branching of the electron capture to a level at (618.1±0.3) keV was observed. The relative probability forK-capturePK618/PK375=0.40 ±0.07 yields a total transition energyQEC=(664 ±4)keV. A spin of 1/2+ was assigned to the ground state.

Der Zerfall des Pt195m und des Au195

The decays of Pt195m(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 Pt195m 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 Pt195m and Au195 the ratios of electron capture branches of Au195→Pt195 decay have been determined.

Der Zerfall des Xe123,T1/2=2,08h

Xe123 (T1/2=2.08 h) was produced by bombarding Te122 with 48 MeV α-particles. The radioactive Xe123 gas was collected during irradiation in liquid air cooled glass ampoules.The gamma rays associated with the decay of Xe123 have been investigated using Ge(Li)- and NaJ(Tl)-counters and a Ge(Li)-NaJ(Tl)-coincidence circuit. 57 gamma transitions in the energy range from 148.7 keV to 2559.1 keV have been found.By depositing the radioactive Xe-ions on Ti-foils sources were obtained thin enough to study the conversion electrons using a Si(Li)-counter. The conversion coefficients for the intensive J123 transitions with low energy were determined.A level scheme for Xe123→J123 which accounts for almost all observed γ-transitions having 16 levels is proposed.Furthermore some new data for the J121 and J123 decay are presented.

Der zerfall des J121 (T1/2=2,12 h)

I121 was produced by bombarding a target of enriched Te122 with deuterons of 25 MeV. Theγ rays associated with the decay of I121 have been investigated using a Ge(Li) detector and a Ge(Li)-NaI coincidence set up. 58γ transitions ranging from 212.5 to 1841.8 keV have been identified. A decay scheme for the I121→Te121 decay which accounts for 50 of the observedγ transitions is proposed.

Der Zerfall der Cäsiumisotope Cs129 und Cs130

Cs129(T1/2=32 h) and Cs130(T1/2=30 min) were produced by J127(α,2n)Cs129and J127(α,n)Cs130reactions, respectively. The γ-ray-spectra from the decays of Cs129 and Cs130 have been investigated using Li-drifted Ge-counters and scintillation spectrometers. In the decay of Cs12915 γ-rays have been observed having the following energies and relative intensities: 95 keV (1.6), 177 keV (1.1), 267 keV (1.7), 278 keV (4.8), 317 keV (7.6), 371 keV (100), 410 keV (69), 511 keV (≦ 0.1), 548 keV (10.5), 587 keV (1.7), 623 keV (0.12), 660 keV (0.07), 864 keV (0.09), 907 keV (0.67) and 948 keV (0.2). The electron capture branching ratios to the ground state and excited states of Xe129were determined; logft values for the various decay branches were derived from these ratios. In the decay of Cs130twoγ-transitions with the following energies and intensities relative to the β+ emission have been found: 535 keV (11) and 585 keV (1.3). A new level at 1122 keV in Xe130is proposed.

Elektroneneinfang beim Zerfall des Ti45

Electron capture to the 718 keV, 1238 keV, 1408 keV and 1665 keV excited states of Sc45 have been observed in the decay of Ti45. The branching ratios were determined to be (0,4±0,04)% (0,05±0,02)%, (0,27±0,03)% and (0,08±0,01)% per decay of Ti45 respectively.

Experimentelle Untersuchung der Čerenkov-Strahlung in optisch einachsigen Kristallen

The relative yields of Čerenkov radiation produced by theβ-rays of P32 by passing through a thin uniaxial crystal plate have been investigated experimentally with the aid of a fast coincidence and a linear gate circuit. Measurements were performed with electrons moving (a) parallel to the optic axis of the uniaxial crystal plate and (b) perpendicular to the optic axis. The experiment showed that the yield of Čerenkov radiation when the electrons moved parallel to the optic axis of the crystal was about 15% higher than in the case of the electrons moving perpendicular to it. This is in good accordance with theory.

Der Zerfall des Xe 123 , T 1/2 =2,08h

Xe123 (T1/2=2.08 h) was produced by bombarding Te122 with 48 MeV α-particles. The radioactive Xe123 gas was collected during irradiation in liquid air cooled glass ampoules.The gamma rays associated with the decay of Xe123 have been investigated using Ge(Li)- and NaJ(Tl)-counters and a Ge(Li)-NaJ(Tl)-coincidence circuit. 57 gamma transitions in the energy range from 148.7 keV to 2559.1 keV have been found.By depositing the radioactive Xe-ions on Ti-foils sources were obtained thin enough to study the conversion electrons using a Si(Li)-counter. The conversion coefficients for the intensive J123 transitions with low energy were determined.A level scheme for Xe123→J123 which accounts for almost all observed γ-transitions having 16 levels is proposed.Furthermore some new data for the J121 and J123 decay are presented.

Der zerfall des J 121 ( T 1/2 =2,12 h)

I121 was produced by bombarding a target of enriched Te122 with deuterons of 25 MeV. Theγ rays associated with the decay of I121 have been investigated using a Ge(Li) detector and a Ge(Li)-NaI coincidence set up. 58γ transitions ranging from 212.5 to 1841.8 keV have been identified. A decay scheme for the I121→Te121 decay which accounts for 50 of the observedγ transitions is proposed.

Der Zerfall des 125 m Xe, des 127 m Xe und des 127 g Xe

AbstractThe decay of125mXe produced by the reaction122Te(α, n)125mXe using a target enriched in122Te (95.4%) and the decay of127mXe produced by the reaction127J(d, 2n)127mXe have been investigated: 125mXe decays with a half-life ofT1/2=(56±3) sec by ayy- cascade withEγ1=(140.4 ±0.5) keV andEγ2=(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. 127mXe decays with a half-life ofT1/2=(71±2) sec. The decay also proceeds by aγγ-cascade with an isomeric E3 transition ofEγ1=(172.5±0.3) keV and a predominantlyM1 transition ofEγ2=(124.6±0.3) keV.In the decay of127gXe an additional branching of the electron capture to a level at (618.1±0.3) keV was observed. The relative probability forK-capturePK618/PK375=0.40 ±0.07 yields a total transition energyQEC=(664 ±4)keV. A spin of 1/2+ was assigned to the ground state.