E. Holzschuh

An upper limit for the mass of upsi;e from tritium β-decay

Abstract The endpoint region of the tritium β -spectrum has been measured with 27 eV resolution, using a magnetic spectrometer. The tritium activity was implanted into a thin layer of carbon. The υ e mass determined is consistent with zero with an upper limit of 18 eV, which includes instrumental and statistical uncertainties due to the energy loss in the source and the final electronic states.

An Upper Limit for the Mass of anti-electron-neutrino from Tritium beta Decay

Abstract The endpoint region of the tritium β -spectrum has been measured with 27 eV resolution, using a magnetic spectrometer. The tritium activity was implanted into a thin layer of carbon. The υ e mass determined is consistent with zero with an upper limit of 18 eV, which includes instrumental and statistical uncertainties due to the energy loss in the source and the final electronic states.

Measurement of the electron neutrino mass from tritium β-decay

Measurements of the tritium s-spectrum are reported. Thin sources consisting of a monolayer of tritiated hydrocarbon molecules were used. No indication of a nonzero mass mν of the electron antineutrino was found. The result is m2ν=−24 ± 48 ± 61 eV2 (1σ). An upper limit mν < 11 eV (95% confidence level) is derived.

Search for heavy neutrinos in the β-spectrum of 63Ni

Abstract The β -spectrum of 63 Ni has been measured with high precision in order to search for effects of heavy neutrinos. For assumed neutrino masses in the range 4 to 30 keV, upper limits of 10 −3 or less are reported for the mixing probability.

The β-spectrum of 35S and search for the admixture of heavy neutrinos

Abstract The β -spectrum of 35 S has been measured with high statistical precision. A total of 2.2×10 10 events have been accumulated with a signal to background ratio of 10 3 or better. A systematic search for neutrino mixing has been performed for assumed neutrino masses up to 105 keV. In the mass range 10 to 90 keV, an upper limit around 10 −3 or less was set for the mixing probability.

Low-temperature muonium depolarization in Si and Ge

Measurements of the normal muonium depolarization rate in high purity silicon and germanium have been performed between 1.5 and 4.2 K. Two different Si samples and one Ge sample were investigated in a transverse field of 5 G, and in all cases, a temperature-independent depolarization rate was observed. The silicon results disagree with earlier work which showed a depolarization rate which decreased with increasing temperature in this temperature range. These results are compared with measurements of the direct muonium hyperfine transition.

The mass of νe from tritium β-decay - first result from the Zürich experiment with a monolayer source

Abstract A report is given on the progress of the the Zurich experiment to measure the mass of ν e . A monolayer tritium source is described. It consists of tritiated hydrocarbon chains covalently bonded onto a surface and has a well-defined structure. The energy loss in the source is very small. Measurements of the backscattering probability and the spectrometer resolution are reported. A first measurement of the tritium spectrum with this source gives a preliminary upper limit for the mass of ν e of 15.4 eV at 95 % CL.

High resolution conversion electron spectroscopy of valence electron configurations

Abstract Measurements of conversion electrons from the outermost valence shells of ion implanted, dilute impurity probe atoms in solids are reported. The measured spectra are directly related to the local density and angular momentum character of the occupied electron states at the probe atom. Thus the valence electron configuration of implanted probe atoms in solids has been investigated. First results for the probes Sn and Ge in Si, Ge, GaAs, Pd, and β-Sn are compared to theoretical calculations.

The transition from Mu to Mu* in diamond

Evidence is presented for a transition from the isotropic muonium state (Mu) to the [111] axially symmetric anomalous muonium state (Mu*) in diamond. Amplitude measurements for Mu* in a powder in zero field and with a single crystal oriented in a magnetic field indicate that such a transition occurs with a temperature-dependent rateΛ(T) and that the electron polarization is conserved during the transition. The possibility of determining the absolute sign of the Mu* hyperfine parameters is discussed.

Hyperfine splitting of muonium in SiO2 powder

The hyperfine splitting of Mu in evacuated SiO2 powder has been measured over the temperature range 17–300 K using the two frequency method. Above 100 K it is consistent with the vacuum value (4463.3 MHz) indicating the Mu atoms are moving freely between the particle grains. At lower temperatures it drops rapidly to 4437±4 MHz at 17 K. The effect is attributed to thermal adsorption on the SiO2 surface. Measurements were also made on an Ar coated powder between 7–62 K. The hyperfine splitting is consistent with the vacuum value over this range.