Professor Dr.rer.nat. Dipl.Phys. Alfons Weber FInstP, MA Ox

Abstract:

The TRIP-t front end board (TFB) will read out Geiger-mode multi-pixel Avalanche Photo-Diodes (GM-APD) in several T2K detector systems. We report the first tests of the TFB electronics with GM-APD. Measurements of GM-APD charge spectra, energy and time resolution have been performed. Individual channel voltage trimming circuit functionality has also been tested. These results indicate very good performance of the TFB prototype with both 400 and 100 pixels GMAPD from Hamamatsu photonics. © Copyright owned by the author(s).

Abstract:

The Tokai-to-Kamioka (T2K) long baseline neutrino experiment goal is to measure vμto ve oscillation parameters using near (280 m) and far (295 km) detectors from the beam origin in the J-PARC accelerator in Tokai. The far detector will be Super-Kamiokande. The 280 m near detectors complex (ND280) contain a number of scintillator based sub-detectors and a beam monitor. Approximately 54,000 scintillator bars will be read out by Multi-Pixel Photon Counter devices (MPPC) via wavelength shifting fibres. It will be the first time this novel type of photo-sensor is used on such a large scale. The front end readout system for the MPPC uses Fermilab Trip-t chips mounted on Trip-t Front end Boards (TFB). The TFB design and measured performance in conjunction with MPPC photo-sensors are presented. © 2007 IEEE.

Abstract:

The velocity of a ∼3GeV neutrino beam is measured by comparing detection times at the near and far detectors of the MINOS experiment, separated by 734 km. A total of 473 far detector neutrino events was used to measure (v-c)/c=5.1±2.9×10-5 (at 68% C.L.). By correlating the measured energies of 258 charged-current neutrino events to their arrival times at the far detector, a limit is imposed on the neutrino mass of mν<50MeV/c2 (99% C.L.). © 2007 The American Physical Society.

Abstract:

The 5.4 kton MINOS far detector has been taking charge-separated cosmic ray muon data since the beginning of August, 2003 at a depth of 207 m.w.e. in the Soudan Underground Laboratory, Minnesota, USA. The data with both forward and reversed magnetic field running configurations were combined to minimize systematic errors in the determination of the underground muon charge ratio. When averaged, two independent analyses find the charge ratio underground to be Nμ+/Nμ-=1.374±0.004(stat)-0.010+0.012(sys). Using the map of the Soudan rock overburden, the muon momenta as measured underground were projected to the corresponding values at the surface in the energy range 1-7 TeV. Within this range of energies at the surface, the MINOS data are consistent with the charge ratio being energy independent at the 2 standard deviation level. When the MINOS results are compared with measurements at lower energies, a clear rise in the charge ratio in the energy range 0.3-1.0 TeV is apparent. A qualitative model shows that the rise is consistent with an increasing contribution of kaon decays to the muon charge ratio. © 2007 The American Physical Society.