F. M. Newcomer

Atmospheric muon-neutrino / electron-neutrino ratio in the multiGeV energy range

Abstract Data from the Kamiokande detector were used to study the atmospheric (v μ + v μ ) (v e + v e ) ratio in the multi-GeV energy range. The observed ratio of μ-like to e-like events relative to the calculated ratio, ( μ /e) data /( μ /e) MC = 0.57 -0.07 +0.08 ± 0.07, suggests that the atmospheric (v μ + v μ ) (v e + v e ) ratio is smaller than expected for these neutrino energies. Also studied was the zenith-angle dependence of the above ratio. Results of an analysis of neutrino oscillations are presented.

Observation of a small atmospheric vμ/ve ratio in Kamiokande

Abstract Results are presented of the observation of atmospheric neutrino interactions in the Kamiokande detector in an exposure of 4.92 kt yr. The observed ratio of single ring μ-events to e-events ( μ e ) data ( μ e ) MC = 0.60 +007 −0.06 ( stat. ) ± 0.05 ( syst. ) suggests that the atmospheric v μ /v e ratio is smaller than expected. The implications of these results for neutrino oscillations are discussed.

Experimental Study of the Atmospheric Neutrino Flux

Abstract We have observed 277 fully contained events in the KAMIOKANDE detector. The number of electron-like single-prong events is in good agreement with the predictions of a Monte Carlo calculation based on atmospheric neutrino interactions in the detector. On the other hand, the number of muon-like single-prong events is 59±7% (statistical error) of the predicted number of the Monte Carlo calculation. We are unable to explain the data as the result of systematic detector effects or uncertainties in the atmospheric neutrino fluxes.

A fast, low power amplifier, shaper and discriminator for high rate straw tracking systems

The ASD-8 is a bipolar integrated circuit that provides eight channels of amplifier, shaper and discriminator on a 2.8-mm by 4.7-mm silicon substrate. It is designed for use in the straw based central tracking system of the SDC detector. Competing requirements for short measurement time ( approximately=5 ns), good double pulse resolution ( approximately=20 ns), low power ( approximately=15 mW/channel), and low operational threshold ( approximately=1 fC) lead to the choice of a largely differential circuit that includes detector tail compensation. Tests of parts from a recent prototype run indicate excellent yield and stable operation with little or no internal crosstalk. >

Performance assessment of pixelated LaBr/sub 3/ detector modules for time-of-flight PET

Our recent measurements with pixelated LaBr/sub 3/ Anger-logic detectors for use in time-of-flight (TOF) PET have demonstrated excellent energy resolution (5.1% at 511 keV) and coincidence time resolution (313 ps full width at half maximum, FWHM) with small prototype configurations . A full size detector module suitable for a whole-body 3D PET scanner has been constructed based on the prototype designs and consists of 1620 4/spl times/4/spl times/30 mm/sup 3/ LaBr/sub 3/ crystals. We have utilized simulations to guide experimental measurements with the goal of optimizing energy and time resolution in evaluating triggering configurations and pulse shaping needed in a full system. Experimental measurements with the detector module indicate energy and time resolution consistent with our earlier prototypes when measured at low count rate. At very high count rate the energy, time and spatial resolution degrade due to pulse pileup. While it is possible to reduce pulse pileup by using smaller photomultiplier tubes (i.e., 39 mm instead of 50 mm diameter), we are trying to limit the total number of PMTs needed for a full-scale PET scanner with a large axial field-of-view. Therefore, we have designed and tested a pulse shaping circuit to improve the detector response and performance at high count rate. Simulations of a complete LaBr/sub 3/ scanner indicate significant improvements in noise equivalent count rate (NEC) and spatial resolution can be achieved using pulse shaping.

Search for neutralino dark matter in Kamiokande

Abstract A search has been made for upward-going muons in the Kamiokande detector as a possible signal from neutralino dark matter captured in the earth. We found the upward-going muon flux from the earth is consistent with that produced by the atmospheric neutrinos. Assuming the galactic halo contains neutralino dark matter, this result provides limits on the neutralino mass in the region 30–80 GeV and gives stringent constraints on the allowed regions of the parameter space in the framework of the minimal supersymmetric standard model.

Experimental limits on nucleon lifetime for lepton+meson decay modes

Abstract We have searched for nucleon decay signals using data from the KAMIOKANDE-II detector. No evidence for nucleon decay has been found. Limits on the nucleon partial lifetime for various decay modes are obtained combining KAMIOKANDE-I and -II data (3.76 kt yr in total). The background subtracted limits at 90% CL range from 0.1×1032yr to 2.6×1032yr depending on the decay modes. For the decay modes p→e+π0, p→ v K+ and n→ v K0, the limits are 2.6×1032yr, 1.0×1032yr and 0.9×1032yr, respectively.

Particle identification using the time-over-threshold method in the ATLAS Transition Radiation Tracker

Abstract Test-beam studies of the ATLAS Transition Radiation Tracker (TRT) straw tube performance in terms of electron–pion separation using a time-over-threshold method are described. The test-beam data are compared with Monte Carlo simulations of charged particles passing through the straw tubes of the TRT. For energies below 10 GeV , the time-over-threshold method combined with the standard transition-radiation cluster-counting technique significantly improves the electron–pion separation in the TRT. The use of the time-over-threshold information also provides some kaon–pion separation, thereby significantly enhancing the B-physics capabilities of the ATLAS detector.

Noise spectral density measurements of a radiation hardened CMOS process in the weak and moderate inversion

The authors have measured the noise of MOS transistors of the United Technology Microelectronics Center (UTMC) 1.2- mu m radiation-hardened CMOS p-well process from the weak to moderate inversion region. The noise power spectral densities of both NMOS and PMOS devices were measured from 1 kHz to 50 MHz. The bandwidth was chosen such that the important components of the spectral densities such as the white thermal noise and the 1/f noise could be easily resolved and analyzed in detail. The effects of different device terminal DC biases and channel geometries on the noise are described.<<ETX>>

An amplifier-shaper-discriminator with baseline restoration for the ATLAS transition radiation tracker

The ASDBLR is a bipolar integrated circuit that provides eight channels of amplifier, shaper, discriminator and baseline restorer on a 6.17 by 4.78 mm silicon substrate. It is designed for use in the straw-based Transition Radiation Tracker (TRT) of the ATLAS detector at the LHC. Competing requirements for short measurement time (/spl ap/8 ns), good double pulse resolution (/spl ap/40 ns), low power (<30 mW/ch), and low operational threshold (/spl ap/1.5 fC) led to the choice of a largely differential circuit which includes detector tail compensation. A capacitively-coupled baseline restorer eliminates effective threshold shifts that would otherwise occur at the high per-wire hit rates (up to 20 MHz). A full-scale dynamic range of 200 fC and two discriminators with separate threshold adjusts allow the ASDBLR to function both as a tracker and a TR photon detector. Selectable ion-tail compensation makes the circuit compatible with both CF/sub 4/ and Xe-based gases.