Gerd Schatz

Elastische und inelastische Streuung von 104 MeV Alpha-Teilchen an58,60,62,64Ni

Differential cross sections are measured for the elastic and inelastic scattering of 104 MeV α-particles from58, 60, 62, 64Ni. The experimental results are analyzed in terms of coupled channels on the basis of an anharmonic vibrational model and prove to be quite sensitive to the values of the deformation parameters. For forward angles the 4+ angular distributions of58,60Ni are dominated by aL=4 single excitation mechanism. This is in keeping with theE4-transitions observed in (e, e′) scattering. From the 21+- and 31+-results transition rates are derived which can be compared to results of electromagnetic methods and of inelastic proton scattering studies. The comparison indicates that the transition rates differ and are generally higher for the proton scattering. Especially in the case of the 3− states of58,60Ni the differences are obvious.The elastic cross sections are analyzed both on the basis of the usual phenomeno-logical model and in terms of a semimicroscopic folding model resulting in values of rms-radii for the nuclear matter distribution.

Relativmessung der Elektronenpolarisation beimxβ-Zerfall: RaE(Bi210)-P32

An apparatus is described for comparing the longitudinal polarization valuesP ofβ-particles from different emitters by the method of double scattering. For RaE(Bi210) and P32 we have measured the ratio of polarization values to be P(RaE)/ P(P32)=0·757±0·022 at 540 keV. This is in good agreement with previous measurements. Ratios of matrix elements are determined from polarization and spectrum shape data of RaE, but these values are not reliable because the spectrum shape shows a systematic discrepancy between theory and experiment below 200 keV. A discussion of electron polarization and spectrum shape data of P32 shows that deviations of polarization from the allowed value are probably very small.An appartus is described for comparing the longitudinal polarization values P of BETA particles from different emitters by the method of double scatiering. For RaE(/sup 210/Bi) and /sup 32/P the ratio of polarization values was measured to be P(RaE)/ P(/sup 32/P) = 0 757 plus or minus 0.022 at 540 kev. This was in good agreement with previous measurements. Ratios of matrix elements were determined from polarization and spectrum shape data of RaE, but these values were not reliable because the spectrum shape showed a systematic discrepancy between theory and experiment below 200 kev. A discussion of electron polarization and spectrum shape data of /sup 32/P showed that deviations of polarization from the allowed value are probably very small. (auth)

A numerical method of analyzing beta decay measurements and its application to the 1− → 0+ transitions of170Tm,186Re and210Bi

A numerical method is proposed for determining nuclear matrix elements from beta decay measurements. The method is based on the least squares principle, and its main application is the analysis of beta ray spectra. Its main result is to show that a spectrum shape measurement usually determines only a second order polynomial of the matrix elements to a high precision whereas each of the matrix elements can vary within wide limits.The method is applied to the first forbidden non unique transitions (1−→ 0+) of170Tm,186Re and210Bi (RaE). The 3 contributing matrix elements and their ranges of error are determined from recent measurements.

Method for alignment of a short magnetic lens beta ray spectrometer by utilizing image rotation

Abstract A simple method for aligning short magnetic lens beta ray spectrometers is described.

Relativmessung der Elektronenpolarisation beim β-Zerfall: Au199 und P32

The ratio of longitudinal polarization values of Re186 and P32β-particles was measured by the method of double scattering. The result obtained isP(Re186)/P(P32)=1,002−0,016+ at 540 keV. The contributions of the ground state transition and the first excited state transition of Re186 are 78% and 22% respectively at this energy for the apparatus used.

Äußerer Photoeffekt und verzögerte Elektronenemission von ultraviolettbestrahlten KCl- und KBr-Einkristallen

ZusammenfassungAn reinen und additiv verfärbten KCl-Einkristallen wurden der äußere Photoeffekt im Energiebereich hv=0,5 bis 3,6 eV sowie die verzögerte Elektronenemission untersucht. An reinem KCl bewirkt Anregung mit Quantenenergien hv≧4 eV bei 100 °K im sichtbaren Spektralbereich einen Photoeffekt, der zeitlich abklingt. Die additiv verfärbten Kristalle zeigen einen Photoeffekt, der einer direkten Ionisation von Gitterfehlstellen zugeschrieben werden kann. Die spektrale Abhängigkeit der Quantenausbeute wurde bestimmt. Die für den Photoeffekt verantwortlichen Zentren bleichen bei den reinen Proben schon bei 100 °K thermisch aus. Dagegen sind die die verzögerte Elektronenemission verursachenden Haftstellen bei dieser Temperatur noch stabil. Die Versuchsergebnisse zeigen, daß äußerer Photoeffekt und verzögerte Elektronenemission unabhängige Prozesse sind, und daß die Photoemission nicht als Photoionisation von Haftstellen gedeutet werden kann. Entsprechende Ergebnisse wurden von KBr erhalten. Jedoch bewirken hier Lichtquanten einer Energie von 2,6 eV bereits eine Anregung.

Relativmessung der Elektronenpolarisation beimβ-Zerfall: Tl204 und P32

The ratio of longitudinal polarization values of Tl204 and P32β-particles was measured by the method of double scattering. The result obtained is P(Tl204)/P(P32)=0.993±0.036 at 540 keV.The low specific activity of the available Tl204 sources caused a considerable depolarization ofβ-particles by scattering in the source. The influence of depolarization was eliminated by using sources containing both nuclei in a chemical compound. The ratio of polarization values can then be calculated from the time dependence of the scattering asymmetry, as the half-lives of Tl204 and P32 differ considerably. An estimate is presented of the influence of inelastic scattering processes in the source on electron depolarization.