Der Zerfall des Co56

Theγ-ray-spectrum of Fe⁵⁶ associated with the E.C.- andβ ⁺-decay of Co⁵⁶ has been measured with Ge(Li)-crystals. 6 newγ-ray-transitions have been found in this spectrum deexciting 3 new levels in Fe⁵⁶. The intensities of these transitions have been estimated and a new level-scheme is proposed. The new levels could be identified with some of previously reported levels found in Fe⁵⁶(p, p′)-measurements.     

K-Einfang der Silberisotope Ag110 und Ag108

K-electron capture of Ag¹¹⁰ has been observed for the first time using scintillation spectrometers in anticoincidence technique. The ratio of electron capture toβ ^?-decay was determined to (0.3±0.06)%.K-electron capture of Ag¹⁰⁸ has been remeasured with better accuracy, yielding a relative frequency of (1.73±0.12)% for the capture transition to the ground state of Pd¹⁰⁸.     

Der Zerfall des Gd151

The electron-capture decay of Gd¹⁵¹ was investigated by means ofγ- andγ-γ-coincidence spectrometry, using scintillation counters. Besides the knownγ-rays of 22 kev, 154 kev, 175 kev, 244 kev and 308 kev additionalγ-transitions with energies of 107 kev and 350 kev could be assigned to the decay of Gd¹⁵¹.γ-γ-coincidence measurements showed the following cascade transitions: (107 kev–244 kev), (154 kev–175 kev–22 kev) and (308 kev–22 kev). TheK-conversion-coefficients of several transitions were determined by comparing theγ-intensities and the previously known conversion electron-intensities, using a direct measurement of theK-conversion-coefficient of the 175 kev-transition by a delayed coincidence-experiment as a normalization of the relative intensities. With the available information a level-scheme for Eu¹⁵¹ is proposed.     

Untersuchung der bisher Ir198 zugeschriebenen 50 sec-Aktivität und Neuzuordnung zum Zerfall von Ir196

Theγ-spectrum of Pt¹⁹¹ has been measured with a Ge(Li)-counter. In addition to earlier measurements about 20 newγ-rays have been found, 10 of them were known as conversion-lines in earlier investigations. The intensities of these conversion-lines and the estimatedγ-ray-intensities allowed the determination of conversion-coefficients. A new level-scheme with 5 new levels at 569, 602, 660, 865 and 940 keV is proposed.     

Der Zerfall des Cu61

Theγ-ray-spectrum of Ni⁶¹ associated with the E.C. andΒ ⁺-decay of Cu⁶¹ has been measured with a Ge(Li)-counter. The observed 14 newγ-ray-transitions led to a new level-scheme for this decay with Ni⁶¹-Ievels at: 67.7, 282.9, 656.0, 907.9, 1099.8, 1132.7, 1186.8, 1610.6, 1730.8 and 2128.0 keV. Five of these levels were known from earlier investigations of Cu⁶¹-decay, but all of them could be identified with some of previously reported levels found in scattering experiments. As far as possible spin and parity assignments have been made and are compared with the results of scattering experiments.     

Der Zerfall des Ruthenium 95

Theγ-spectrum of Tc⁹⁵ associated with the E.C.- and β⁺-decay of Ru⁹⁵ has been measured with a Ge(Li)-counter and a NaJ-crystal. 12 newγ-ray transitions have been found in these spectrums. To propose a new level-schemeγ-γ-coincidences have been taken with 2 NaJ-crystals in a two-dimensional device. Besides this the total conversion coefficient of the 336 keV transition was measured by detecting the electrons in a Si(Li)-counter and theγ-rays in a NaJ-crystal.     

Search for double beta decay of <Superscript>106</Superscript>Cd in the TGV-2 experiment

An investigation of double beta decay (β⁺β⁺, β⁺/EC, EC/EC) of ¹⁰⁶Cd was performed at the Modane underground laboratory (at a water equivalent depth of 4800 m) using a TGV-2 spectrometer with 32 detectors. Evaluation of the experimental data accumulated over 12 400 h of measuring ～13.6 g of ¹⁰⁶Cd with an enrichment of 75% was performed. New limits (at a confidence level of 90%) on the half-lives of the 0νEC/EC resonant decay of ¹⁰⁶Cd to the 2741 keV excited state of ¹⁰⁶Pd ? T _1/2 ≥ 1.5 × 10²⁰ y and on 2νEC/EC decay to the ground state of ¹⁰⁶Pd (0⁺ → 0⁺, g.s.) ? T _1/2 ≥ 3.9 × 10²⁰ y were obtained. The limits of the 2νEC/EC decay of ¹⁰⁶Cd to the 2⁺, 512 keV and 0 ₁ ⁺ , 1334 keV excited states of ¹⁰⁶Pd and 2νβ⁺β⁺- and the 2νβ⁺ EC decays of ¹⁰⁶Cd to the ground and excited states of ¹⁰⁶Pd were improved.     

Zerfallsschema und Matrixelemente für denβ-Übergang Ag110m→Cd110

Theβ decay Ag^110m→Cd¹¹⁰ has been investigated with a double lens spectrometer and aβ-γ circular-polarization correlation setup. The shape of the 6⁺→6⁺ β spectrum withE ₀=529 keV was found to be allowed, in disagreement with earlier work. The constantA of theβ-γ circular-polarization correlation was measured to beA=0·07±0·02. This implies a ratioX of Fermi to Gamow-Teller contribution to the decay ofX ₁=?0·02±0·03 orX ₂=?10·3 _?4·1 ^+2·3 . Qualitative shell model considerations favor the valueX ₁. Additional information is given for the disintegration schemes of Ag^110m and Ag¹¹⁰.     

Dipole moment functions for electronic transitions from ion-pair states of the second tier of molecular iodine

The emission spectra caused by the transitions from the ion-pair states and f0 _g ⁺ and G1_g of the I₂ molecule are obtained by excitation of individual rovibronic levels of the molecule by the method of optical-optical double resonance. The emission spectra from the state F0 _u ⁺ populated due to collisions I₂(f) + I₂(X) are also measured. By modeling the experimental emission spectra, the dipole moment functions for the electronic transitions f _g ⁺ -B0 _u ⁺ , A0 _u ⁺ , and B″0 _u ⁺ ; G1_g-A0 _u ⁺ and B″0 _u ⁺ ; and F0 _u ⁺ -X0 _g ⁺ and a′0 _g ⁺ of the iodine molecule are reconstructed.     

Spins und γ-Multipolordnungen beim Zerfall Fe59→Co59

In the decay of Fe⁵⁹ the following quantities have been measured:γ-ray intensities, conversion coefficients andβ-(circularly polarizedγ) correlations. The conversion coefficients were found to be: for the 1.10 MeVγ-transition, α_tot.=(1.36±0.10)·10^?4 and for the 1.29 MeVγ-transition, α_tot.=(1.07±0.08)·10^?4. The asymmetry parameterA of the correlationβ(0.27 MeV)?γ(1.29 MeV) were measured to beA= ?0.17±0.10, and forβ(0.46 MeV)?γ(1.10 MeV),A=?0.13±0.04. From these data and publishedγ?γ angular correlation measurements the following spins of Co⁵⁹ levels could be deduced: 1.10 MeV,I=5/2^?; 1.29 MeV,I=5/2^?; and 1.43 MeV,I=3/2^?. The two strongβ-ray groups are pure Gamow-Teller transitions (ΔI=1). The multipolarities of all fiveγ-rays are given.     

Ausbeuteverhältnisse einiger durch Kernphotoreaktionen in Cer und Silber erzeugter Aktivitäten

Samples of metallic silver and cerium-oxide have been irradiated with 31 MeV and 34 MeV bremsstrahlung. Relative yields of the induced activities have been obtained by counting the emitted gamma-quanta or byβ-counting. The yield ratio Y [Ag¹⁰⁷ (γ, n) Ag^106m ]/Y [Ag¹⁰⁷ (γ, n) Ag^106g ] for 34 MeV bremsstrahlung was found to be (0.08±0.02). The corresponding ratio Y [Ce¹⁴⁰ (γ, n) Ce^139m ]/Y [Ce¹⁴⁰ (γ, n) Ce^139g ] at 31 MeV was (0.19±0.01).     

Messung der K-Konversionskoeffizienten der isomeren Atomkerne Pd107m und Pd109m

TheK-conversion coefficients α _K of the isomers Pd^107m and Pd^109m have been measured by detecting theKX-rays and gamma-rays from neutron-irradiated Pd-samples with the aid of a NaJ(Tl)-scintillation spectrometer. The results are α _K =0,41±0,02 and α _K =0,52±0,04, respectively. These values have been compared with those taken from the tables of Rose, confirming the assumption of E3-transitions which was proposed earlier by other authors. In addition, the assignment of the 21 sec-activity to Pd^107m has been confirmed.     

Radiative transitions to localized Eu states in Pb<Subscript>1−<Emphasis Type="Italic">x</Emphasis></Subscript>Eu<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript>Te solid solutions

Two types of radiative transitions were observed in the low-temperature photoluminescence spectra of Pb_1?x Eu _x Te (0 ≤ x ≤ 0.09) solid solutions: an intense line corresponding to the transitions from the conduction to the valence band and a series (up to 15) of narrow lines corresponding to the transitions from the hybridized conduction band to the split Eu³⁺ levels. The intensity of the discrete lines increases with x, and their energies (and intensities) weakly depend on the temperature. The absorption and emission of the discrete lines are caused by the 4f ⁷(⁸ S _7/2) ? 4f ⁶(⁷ F _J )[L ₆ ^? + 5dt _2g ] transitions.     

Measurement of the nuclear magnetic dipole moment of Au197 and hyperfine structure measurements in the ground states of Au197, Ag107, Ag109 and K39

Using an atomic beam magnetic resonance apparatus the nuclear magnetic dipole momentμ _I of the stable isotope Au¹⁹⁷ was measured directly with the doublet method. The result isμ _I(Au¹⁹⁷)=0.143491 (9)μ _n, uncorrected for atomic diamagnetism. Further hyperfine structure measurements were performed in the ground states of K³⁹, Ag¹⁰⁷, Ag¹⁰⁹ and Au¹⁹⁷ with the following results:Δv(K³⁹)=461.719723 (38) MHzΔv(Ag¹⁰⁷)=1712.512111 (18) MHzΔv(Ag¹⁰⁹)=1976.932075 (17) MHzΔv(Au¹⁹⁷)=6099.320184 (13) MHzg _J(Ag¹⁰⁷)/g _J(K39)=1.0000260 (20)g _J(Au¹⁹⁷)/g _J(K39)=1.0005076 (20).     

Selective Reflection of Potassium Vapor Nanolayers in a Magnetic Field

The selective reflection of laser radiation from the interface between a dielectric window and the atomic vapors confined in a nanocell of thickness L ≈ 350 nm is used to develop effective Doppler-broadening- free spectroscopy of potassium atoms. A small atomic line width and a relation between the signal intensity and the transition probability allowed us to resolve four lines of atomic transitions responsible for the D1 lines of the ³⁹K and ⁴¹K isotopes. Two groups containing four atomic transitions form in an applied magnetic field upon pumping by radiation with circular polarization σ⁺ or σ^–. Different intensities (probabilities) of transitions for the σ⁺ and σ^– excitations are detected in magnetic field B₀ ≈ A _hfs /μ_B ≈ 165 G (A _hfs is the magnetic dipole constant for the ground state and μ_B is the Bohr magneton). A substantially different situation is observed at B ? B₀, since high symmetry appears for the two groups formed by radiation with circular polarization σ⁺ or σ^–. Each group is the mirror image of the other group with respect to the frequency of the 4²S_1/2–4²P_1/2 transition, which additionally proves the occurrence of the complete Paschen–Back regime of the hyperfine structure at B ≈ 2.5 kG. A developed theoretical model well reproduces the experimental results. Possible practical applications are described. The results obtained can also be applied to the D₁ lines of ⁸⁷Rb and ²³Na.     

Pion-pion interaction andK 2x03C0;x03C0;x03C0;-decay

The enhancement of theK _2π ⁺ -decay compared to theK _2π ⁰ -decay is discussed on the basis of the\(|\mathop {\Delta {\rm I}}\limits^ \to | = \tfrac{1}{2}\)-rule. The enhancement factor is calculated by dispersion methods which yield an expression depending only on the phase shift of the two pion system in theJ=0,I=0,2 state. This expression has been studied in the framework of simple models for the two-pion interaction in order to obtain a survey of the possibilities for the cause of the anomalous large ratioK _2π ⁺ /K _2π ⁰ . Only characteristic cases have been considered and, as far as possible, experimental results of theπ-π-interaction are taken into account.     

Zerfallsschema und β-Spektrum des MsTh1 (Ra228)

Theβ-spectrum of MsTh1 (Ra²²⁸) has been measured in a proportional counter in 2π — and in 4π-geometry. Comparison of these measurements shows that there are no conversion electrons. Theβ-decay of MsTh 1 therefore leads in all cases to the ground level of MsTh2. The Kurie plot is straight from 15 keV up to the upper energy limit ofE ₀=55±3 keV (logft=5·6). The result has been checked by a search for photons emitted by the MsTh1. Noγ-rays and no X-rays have been found. The measurements had to be made with a relatively large amount of natural Ra²²⁶ in the sources. — The results do not agree with those ofLecoin, Perey, Teillac andRiou, who proposed a complex decay sheme for MsTh1.     

Der Zerfall des Mn52m

Mn^52m(T _1/2=21 m) was produced by irradiating iron-foiles with deuterons ofE _d =9 MeV. Coincidences ofγ-rays with the main 1434 keV-transition had been sought for with the aid of a scintillation fast-slow-coincidence circuit. There was no evidence ofγ-lines which had been found earlier byKatoh et al. atγ-energies 700, 940, 1020, 1150, 1370, 1520 keV. If these transitions exist, their relative intensities are less than 0.7% (700 keV) and 0.3% (all others) per decay of Mn^52m.