K. W. Hoffmann

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 ΩitK=0.653 ± 0.004. Taking in consideration former measurements1 one concludes a continuous behaviour of ΩitK(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 beT1/2=(34.5 ± 0.2) d.

Formfaktor des Betaspektrums von146Pm

The β-spectrum of the 3−-2+ transition in the decay of146Pm has been investigated with a 4π-Si(Li)-semiconductor spectrometer in a β-γ-coincidence experiment for the first time. The shape factor has been determined: C(W)=1−0.394W}-0.275/W+0.044 W2.The spin and parity of the ground state of146Pm can be determined to be 3−. The shape of this non-allowed spectrum indicates the existence of the “cancellation” or “selection rule” effect.

Konversionskoeffizient von69mZn und Fluoreszenzausbeute von Zink

The decay of69mZn and69Zn has been investigated using a radioactive source obtained by irradiating a sample of 99%68ZnO with neutrons. Theβ-spectrum of69Zn and the conversion electrons of the69mZn decay have been studied with an anthracene scintillation spectrometer of the split crystal type. The measured value of the conversion coefficient of69mZn is α=0.054±0.003. With this result and those obtained by measurement of theγ-ray spectra of69mZn with NaI(Tl) scintillation crystals, theK-fluorescent yield of Zn has been determined to be ωK=0.45±0.04.

Messung des Wirkungsquerschnitts fr Ionisierung in derK-Schale durch Elektronensto

Absolute cross sections forK-shell ionisation in thin foils of Ag and Cu by electron impact have been determined from NaJ(Tl) scintillation spectrometer measurements ofK-x-rays and with the aid of a β-ray spectrometer. The energies of the bombarding electrons have been 114keV for Ag and 81 keV, 114keV and 152 keV for Cu. The results for Cu are in excellent agreement with the relavistic calculations of Arthurs and Moiseiwitsch. A brief discussion of the values obtained in comparison with earlier experimental and theoretical results will be given.

Mößbauereffekt in FeCl2, FeSO4 und FeSO4 · 7 H2O

Mößbauereffect measurements were performed with FeCl2, FeSO4 and FeSO4 · 7 H2O in the temperature range between 5 and 300 ‡K. The quadrupole splittings at 5 ‡K were determined to be (1.300±0.027) mm/sec, (3.650±0.053) mm/sec, and (3.350±0.053) mm/sec respectively. From the temperature dependence of the quadrupole splittings it follows that in FeCl2 the energy of the excited 3d-electron-level isδ=150 cm−1, in FeSO4δ1=360 cm−1 andδ2=1680 cm−1 and in FeSO4 · 7 H2Oδ1=480 cm−1 andδ2=1300 cm−1. The magnitudes of the magnetic field at the iron nucleus at 5 ‡K are (202±8) kOe for FeSO4 and (0±4) kOe for FeCl2.

Messung derK-Fluoreszenzausbeute von Silber und Antimon

Atoms of thin Ag- and Sb-targets have been ionized by electron impact and the followingK-X-rays andK-Auger-electrons were measured simultaneously. A scintillation counter was used for the X-rays and an electrostatic mirror spectrometer with a Si-Li-detector for the electrons. From these measurements we obtained for the fluorescence yields for Ag and Sb ωK(Ag) = 0.834±0.017; ωK(Sb) = 0.868±0.014.These results are in agreement with the measurements of Foin et al. [2] for Ag, of Hribar et al. [3] for Sb and with the theories of McGuire [10] and Kostroun et al. [11].

Measurement of the longitudinal electron polarization in nuclear beta-decay

Measurements were made to determine the longitudinal electron polarization of theβ−-decays of Ca-45, Pm-147 and Tl-204. Theβ−-transition of Co-60 served as a reference standard and all measurements were carried out relative to it thus strongly reducing the instrumental errors. The measuring principle is based on Mott-scattering technique with a Mott-analyzer similar to that of van Klinken [1] and a Wien-filter for spin transformation from longitudinal to transverse. For each isotope several measurements were carried out at different electron energies ranging from 80–200 keV. In summary, not a single deviation from the theoretical value of -v/c was found.

TheK-fluorescence yield of chlorine and bromine

Using a multiwire proportional counter with CH4 and Ar as counting gases, theK-fluorescence yield of chlorine was determined to beωK=0.101±0.004, and theK-fluorescence yield of bromine was found to beωK=0.626±0.012. The respective sources were37Ar and81Kr, the latter produced by a (n, γ)-reaction from80Kr. The ωK-value of chlorine correlates with the theoretical computation of Walters and Bhalla [1], compared to that of bromine, which seems to confirm the theory of Kostroun et al. [18].

Mößbauereffekt in FeCl 2 , FeSO 4 und FeSO 4 · 7 H 2 O

Mößbauereffect measurements were performed with FeCl2, FeSO4 and FeSO4 · 7 H2O in the temperature range between 5 and 300 ‡K. The quadrupole splittings at 5 ‡K were determined to be (1.300±0.027) mm/sec, (3.650±0.053) mm/sec, and (3.350±0.053) mm/sec respectively. From the temperature dependence of the quadrupole splittings it follows that in FeCl2 the energy of the excited 3d-electron-level isδ=150 cm−1, in FeSO4δ1=360 cm−1 andδ2=1680 cm−1 and in FeSO4 · 7 H2Oδ1=480 cm−1 andδ2=1300 cm−1. The magnitudes of the magnetic field at the iron nucleus at 5 ‡K are (202±8) kOe for FeSO4 and (0±4) kOe for FeCl2.

Mößbauereffekt in FeCl2, FeSO4 und FeSO4 · 7 H2O@@@Mößbauereffect in FeCl2, FeSO4 and FeSO4 · 7 H2O

Mößbauereffect measurements were performed with FeCl2, FeSO4 and FeSO4 · 7 H2O in the temperature range between 5 and 300 ‡K. The quadrupole splittings at 5 ‡K were determined to be (1.300±0.027) mm/sec, (3.650±0.053) mm/sec, and (3.350±0.053) mm/sec respectively. From the temperature dependence of the quadrupole splittings it follows that in FeCl2 the energy of the excited 3d-electron-level isδ=150 cm−1, in FeSO4δ1=360 cm−1 andδ2=1680 cm−1 and in FeSO4 · 7 H2Oδ1=480 cm−1 andδ2=1300 cm−1. The magnitudes of the magnetic field at the iron nucleus at 5 ‡K are (202±8) kOe for FeSO4 and (0±4) kOe for FeCl2.