W. Lampert

Das spektrum der inneren bremsstrahlung beim β-zerfall von 90Y und 90Sr

Zusammenfassung The spectra of internal bremsstrahlung from the beta decays of 90Y and 90Sr have been measured absolutely with a scintillation spectrometer. The spectra are corrected for external bremsstrahlung, for efficiency in the NaI(Tl) crystal, for absorption in the crystal mounting and for pile-up. The absolute beta activity was determined by measurements with a 4π-scintillator and by measurements with well defined geometry. The results are compared with theoretical calculations of Knipp, Uhlenbeck and Bloch, of Lewis and Ford and of Felsner and Gebhardt. For 90Y the results are for lower energies (≦ 500 keV) in agreement with Knipp et al. For higher energies, they are better represented by Felsner and Gebhardt. For 90Sr the results agree with Felsner and Gebhardt for lower energies (≦ 200 keV). For higher energies they lie higher than those calculations. The beta decay of 90Y→90Zr was observed over more than 16 half-lives. The lifetime was found to be T 1 2 = 64.6±0.8 h .

Untersuchung der inneren bremsstrahlung von 32P und 90Y: (Winkelkorrelation und spektrum)

Abstract The internal bremsstrahlung of 32 P and 90 Y is studied with various methods of measurement. The measurement of the energy spectrum and the integral angular correlation of 32 P and the measurement of the differential energy spectrum of 90 Y at angles Θ = 22.5°, 30°, 45° and 90° is described. The experimental results are compared both with the experimental results ofother authors and with theoretical calculations.

Lifetime and g-factor of the 181 keV level in 78Br

Abstract Low-lying states of 78 Br were populated by means of the nuclear reaction 78 Se(p, n) 78 Br. The observed γ-transitions were fitted into a level scheme. The half-life of the isomeric state at 181 keV was remeasured. Our result T 1 2 = 80 ± 2 μ s differs from the measurements of other groups. The g -factor of this state was determined to be g = +1.02 ± 0.02 with the pulsedbeam DDCA method.

The magnetic moment of the first excited state in 66Ga

Abstract The g-factor of the first excited state in 66Ga (Eγ = 43.8 keV; Jπ = 1+) was measured by the DPAD method. The experimental value is g = −0.504±0.009. A comparison with shell-model calculations for different configurations is carried out. A re-measurement of the half-life yields T 1 2 = 24.6±2.0 ns .

The g-factor of the isomeric 92+ state of 81Br

Abstract The g-factor of the isomeric 9 2 + state of 81Br at 541 keV ( T 1 2 = 32 μs ) was measured by the stroboscopic method. The experimental value g = 1.261 ± 0.010 is compared with shell model calculations.

Rotation of the plane of polarization of γ-radiation by hyperfine interaction

Abstract The orientation of the plane of polarization as well as the degree of linear polarization of γ-radiation is investigated in an external magnetic field.

Entfaltung kontinuierlicher γ-impulshöhenverteilungen

Abstract In order to unscramble continuous pulse height distributions, measured with a scintillation spectrometer, to the true incident photon spectrum, especially of the internal bremsstrahlung, a special method is necessary. The formation of the unscrambling matrix and the energy spectra, which are received as solutions of linear systems of equations, are discussed. The matrix is tested by using discrete γ-spectra. The oscillations, which occur when the systems of equations are solved, are studied and an iterative method for unscrambling is described, which is able to suppress these oscillations. The limit of the efficiency of the method is given.

Untersuchung der niedrigliegenden Niveaus des54Fe durch die (p,p′γγ)-Reaktion

The low-lying levels of54Fe were studied. The method ofγ γ-triple-correlations was used. Angular distributions were also measured. The levels at 2.5 MeV were found to be a doublett, withI=0(+) for the 2563 keV-level andI=4(+ or 2(+) for the lower level at 2539 keV. The experimental level scheme is compared with calculations according to nuclear models.

γγ-Tripelkorrelationsmessungen am Fe56 bei (pp′ γγ)-Reaktionen

The investigations ofγγ-triple correlations following (pp′)-reactions are used to determine the spins of the second and third excited level in Fe56 and theE2/M1 mixing ratio of the transition from the third to the first excited level. The population numbers of the substates are also determined. AtEp=4.9 MeV the correlation associated with the second level was measured. AtEp=5.5 MeV the correlations associated with the second and third level and the angular distributions of the photons were investigated. The spin series of 0ü, 2ü, 4ü, 2ü and a mixing ratio ofδ=0.20 was obtained. The results of the angular distributions and the correlations are compared. They agree well with experimental results of other authors, obtained by various methods of measurement, and with theoretical predictions.

Messung der Linearpolarisation der 245 keV-γ-Strahlung in111Cd

A Compton polarimeter for linear polarization measurements ofγ-quanta existing of two thin NaI-crystals is described. The linear polarization correlation of the 171–245 keV cascade in111Cd was measured. TheE2-character of the 245 keV quanta follows immediately from this correlation measurement. The mixing ratioδ of the 171 keV quanta was confirmed to beδ1=+0.145. The polarization sensitivity of the polarimeter is discussed.