O. Kazachenko

High precision measurement of the tritium β spectrum near its endpoint and upper limit on the neutrino mass

Abstract The Mainz neutrino mass experiment investigates the endpoint region of the tritium β decay spectrum to determine the mass of the electron antineutrino. By the recent upgrade the former problem of dewetting T2 films has been solved and the signal-to-background-ratio was improved by a factor of 10. The latest measurement leads to m ν 2 =−3.7±5.3 stat ±2.1 sys eV 2 /c 4 , from which an upper limit of m ν eV/c 2 (95% C.L.) is derived. Some indication for the anomaly, reported by the Troitsk group, was found, but its postulated half year period is contradicted by our data.

Direct search for neutrino mass and anomaly in the tritium beta-spectrum: Status of “Troitsk neutrino mass” experiment

Abstract Results of the “Troitsk ν-mass” experiment on search for the neutrino rest mass in the tritium beta-decay are presented. New data on the time dependence of the anomalous, bump-like structure at the end of the beta spectrum reported earlier are discussed. Possible systematics is considered in view of contradiction of “Troitsk nu-mass” observation with those of “Mainz neutrino” set-up. An upper limit for electron antineutrino rest mass remains at m ν 2.5eV c 2 at 95% C.L.

The Mainz neutrino mass experiment

Abstract The Mainz neutrino mass experiment is investigating the endpoint region of the tritium β decay spectrum to determine the mass of the electron antineutrino. With its recently improved setup data were taken over more than 7 month in 1998 and 1999. For these measurements two different analyses are presented leading to mv2 = +0.6±2.8±2.1 eV2/c4and mv2 = −1.6 ± 2.5 ± 2.1 eV2/c4, from which upper limits of mv

Neutrino mass and anomaly in the tritium beta-spectrum. Results of the “Troitsk ν-mass” experiment

Abstract Results of the “Troitsk ν-mass” experiment on the search for the neutrino rest mass in the tritium beta-decay are presented. Study of time dependence of anomalious, bump-like structure at the end of beta spectrum reported earlier gives indication of periodic shift of the position of the bump with respect to end-point energy with period of 0.5 year. New upper limit for electron antineutrino rest mass m ν eV / c 2 is derived after accounting for the bump. Possible variants of more sensitive facility are discussed.

Newest results from the Mainz neutrino mass experiment

The Mainz neutrino-mass experiment investigates the endpoint region of the tritium β-decay spectrum with a MAC-E spectrometer to determine the mass of the electron antineutrino. By the recent upgrade, the former problem of dewetting T2 films has been solved, and the signal-to-background ratio was improved by a factor of 10. The latest measurement leads to \(m_\nu ^2 = - 3.7 \pm 5.3(stat.) \pm 2.1(syst.){{eV^2 } \mathord{\left/ {\vphantom {{eV^2 } {c^4 }}} \right. \kern-\nulldelimiterspace} {c^4 }}\), from which an upper limit of \(m_\nu < 2.8{{eV^2 } \mathord{\left/ {\vphantom {{eV^2 } {c^2 }}} \right. \kern-\nulldelimiterspace} {c^2 }}(95\% C.L.)\) is derived. Some indication for the anomaly, reported by the Troitsk group, was found, but its postulated half-year period is contradicted by our data. To push the sensitivity on the neutrino mass below 1 eV/c2, a new larger MAC-E spectrometer is proposed. Besides its integrating mode, it could run in a new nonintegration operation MAC-E-TOF mode.

Ion source for tests of ion behavior in the Karlsruhe tritium neutrino experiment beam line

An electron-impact ion source based on photoelectron emission was developed for ionization of gases at pressures below 10(-4) mbar in an axial magnetic field in the order of 5 T. The ion source applies only dc fields, which makes it suitable for use in the presence of equipment sensitive to radio-frequency (RF) fields. The ion source was successfully tested under varying conditions regarding pressure, magnetic field, and magnetic-field gradient, and the results were studied with the help of simulations. The processes in the ion source are well understood, and possibilities for further optimization of generated ion currents are clarified.An electron-impact ion source based on photoelectron emission was developed for ionization of gases at pressures below 10 mbar in an axial magnetic field in the order of 5 T. The ion source applies only DC fields, which makes it suitable for use in the presence of equipment sensitive to radiofrequency (RF) fields. The ion source was succesfully tested under varying conditions regarding pressure, magnetic field and magnetic-field gradient, and the results were studied with the help of simulations. The processes in the ion source are well understood and possibilities for further optimization of generated ion currents are clarified.

Newest results from the Mainz neutrino-mass experiment

AbstractThe Mainz neutrino-mass experiment investigates the endpoint region of the tritium β-decay spectrum with a MAC-E spectrometer to determine the mass of the electron antineutrino. By the recent upgrade, the former problem of dewetting T2 films has been solved, and the signal-to-background ratio was improved by a factor of 10. The latest measurement leads to

New results from the mainz neutrino mass experiment

m_\nu ^2 = - 3.7 \pm 5.3(stat.) \pm 2.1(syst.){{eV^2 } \mathord{\left/ {\vphantom {{eV^2 } {c^4 }}} \right. \kern-\nulldelimiterspace} {c^4 }}