K. Ukai

Trigger system for the TOPAZ detector at TRISTAN, KEK

Abstract A trigger system for the TOPAZ detector at the TRISTAN e + e − collider has been developed. The system consists of an energy trigger and a track trigger. The track trigger uses track information from the inner drift chamber, the time-of-flight counters and the time projection chamber. A three-dimensional track reconstruction is performed with high-speed logic arrays. The design and the performance are described.

The TOPAZ inner drift chamber

We have constructed a cylindrical drift chamber with anode and cathode delay-line readouts, which is the innermost tracking device of the TOPAZ detector. This inner drift chamber (IDC) is used for the tracking of charged particles in both rφ and rz planes. Fast track-finding logics have been developed for the event triggering. We describe the design, the construction and the performances of the IDC in the first beam run.

High sensitivity search for a 17 keV neutrino. Negative indication with an upper limit of 0.095

Abstract We have performed a search for a 17 keV neutrino by looking for a kink in the 63 Ni β-spectrum near the expected energy threshold. Using a large number of events (2.4 × 10 9 ) accumulated in a narrow energy region with the INS iron-free π √2 β -spectrometer, we obtain a mixing strength of [1.8±3.3(stat.)±3.3(syst.)]×10 −4 , and no indication of the presence of a 17 keV neutrino with the order of 1% mixing. We set an upper limit of 0.095% for the admixture of a neutrino with a mass of 17 keV and of 0.1% with a mass range of 10–24 keV, at the 95% confidence level.

Photon Tagging System at the INS Electron Synchrotron

A photon tagging system which determines the energy of each photon in the bremsstrahlung process is constructed, and is tested using an extracted electron beam from the 1.3 GeV electron synchrotron at the Institute for Nuclear Study, University of Tokyo. The system which consists of an analyzing magnet and twenty-five tagging counters detects the recoil electrons in the energy range from 100 MeV to 350 MeV. The energy of each tagged photon has been calibrated with a total absorption type lead glass Cerenkov counter. A good agreement within the error of ±10 MeV is obtained between the energy measured by the Cerenkov counter and the one calculated from the trajectory of the recoil electron. From the first experiment using this system, it is found that the intensity of the tagged photon beam is limited to 105 photons/s.

An Upper Limit for the Mass of the Electron Anti-neutrino From the Ins Experiment

Abstract The β-spectrum in 3 H decay has measured at INS with an energy resolution of 10–16 eV. The overall response function of the spectrometer system was reliably obtained with a reference 109 Cd source having the same chemical structure as the 3 H source. An upper limit of 32 eV has been obtained for the mass of the electron anti-neutrino with statistical and systematic errors.

Precise measurement of Ag KLL Auger-spectrum

Abstract The Ag KLL Auger spectrum has been measured with an energy resolution of 8 eV. The energies and the intensities of all nine lines are precisely determined with 1–2 orders of magnitude better accuracies than those in the previous experiment. The data obtained are found to be in good agreement with the theoretical calculations.

Measurement of polarized target asymmetry in γd → pn in the photon energy region between 0.3 and 0.7 GeV

Abstract The target asymmetry in γ d → pn has been measured at proton c.m. angles of 70°, 100° and 130° in the photon energies between 0.3 and 0.7 GeV. Results show relatively small asymmetry values in contrast to large proton polarizations. A phenomenological analysis by Ikeda et al. does not reproduce the present data, especially in the lower energy region.

Observation of the leading K∗L-excitation series from JP = 1− through 5− in the reaction K− p → K− π+ n AT 11 GeV/c

Abstract High statistics data for the reaction K−p→K−π+n at 11 GeV/c have been obtained in the LASS spectrometer at SLAC. A spherical harmonic moments analysis provides clear evidence for the production of the complete leading orbitally excited K∗ series up through JP = 5−. New measurements are made of the masses and widths of the 1−K∗(892), 2+K∗(1430 ), 3− K∗(1780), and 4+ K∗(2060), and evidence is presented for the production of a new K∗ state at 2382 MeV/c2 with spin-parity 5−.

Study of energy loss of 18 keV β-rays in a Langmuir-Blodgett thin film

Abstract The energy loss of 18 keV β-rays in a very thin Langmuir-Blodgett film of a chemical compound, arachidic acid, has been studied.

Neutrino Mass and End-Point Energy of ^3H β-Decay

The end-point energy of 3 H β-decay is re-examined and found as E 0 =18582.5±4.1 eV by a new measurement of the electron energy spectrum at INS. Also, an upper limit of the electron anti-neutrino mass is obtained as m ν <29 eV by combining with the result of a previous experiment.