A. Murakami

The CDF central electromagnetic calorimeter

The central electromagnetic calorimeter for the Collider Detector at Fermilab uses a hybrid design with scintillator and wavelength shifter for energy measurement and an embedded strip chamber for position determination and longitudinal shower development. Complementary calibration systems are incorporated in the design. Calorimeter characteristics and performance are summarized. An average energy resolution, σ(E)E, of 13.5%√E sin θ (with E in GeV), and a position resolution of ±2 mm at 50 GeV are measured.

Aerogel Cherenkov counter for the BELLE detector

In the BELLE experiment at the KEK B-factory, a threshold aerogel Cherenkov counter, with refractive index from 1.010 to 1.030, is used to provide p/K separation in the momentum region up to 3.5 GeV/c. The detector system has been constructed, installed into the BELLE detector, and then commissioned with cosmic rays and beams. This paper presents a brief explanation of the detector system and its performance obtained in early BELLE physics runs. ( 2000 Elsevier Science B.V. All rights reserved.

Microdischarges of AC-coupled silicon strip sensors

Abstract Microdischarge at the edges of strips in AC-coupled silicon strip sensors has been investigated. A steep increase in the leakage current (breakdown) and a sudden onset of burst noise were observed at a low reverse-bias voltage when the bias potential was across the AC-coupling capacitor. This can be explained by the occurrence of microdischarges along the edges of strips. These discharges have been confirmed by observing IR light emission. A calculation of the field strength at the strip edge suggests that a fringe field of the external electrode generates the microdischarge at the strip edge when the bias voltage is 50–80 V. This is consistent with our observations. We discuss a design for AC-coupled sensors that eliminates this discharge problem.

Evidence for hard scattering of hadronic constituents of photons in photon-photon collisions of TRISTAN

Abstract We present results of an experimental study of e + e − + hadrons in the kinematic regime for which the process is interpreted as hadron production in collisions of almost-real photons. The data sample corresponds to an integrated luminosity of 27.5 pb − and covers center-of-mass energies from 55 to 61.4 GeV. We observe more events than expected from the incoherent sum of quark-parton and vector-meson-dominance models, and we give a quantitative explanation of the excess by including the hard scattering of the hadronic constituents of the photons calculated with QCD.

Measurements of the inclusive jet cross section in photon-photon interactions at TRISTAN

Abstract We present cross section measurements for inclusive jet production in almost-real photon-photon interactions at TRISTAN using the AMY detector. The results are compared with leading-order QCD calculations for different parameterizations of the parton density in the photon.

Double-sided microstrip sensor for the barrel of the SDC silicon tracker

Abstract A full-size prototype microstrip sensor for the silicon tracker of the SDC detector to be used at the Superconducting Super Collider has been fabricated at Hamamatsu Photonics. The sensor is double-sided, using an AC-coupled readout with 50 μm pitch strips. The sensor size is 3.4 × 6.0 cm 2 . Polycrystalline silicon is used as a bias feeding resistor on both surfaces. Each ohmic strip is isolated by a p + blocking line. The detailed requirements for the silicon tracker and the corresponding specifications as well as how to achieve them are discussed. The static performances of this prototype sensor are presented.

A measurement of the photon structure function F2

Abstract The photon structure function F2 has been measured at average Q2 values of 73,160 and 390 ( GeV c ) 2 . We compare the x dependence of the Q2 = 73 ( GeV c ) 2 data with theoretical expectations based on QCD. In addition we present results on the Q2 evolution of the structure function for the intermediate x range (0.3⩽ x ⩽0.8). The results are consistent with QCD.

A high-Q2 measurement of the photon structure function F2γ

Abstract The photon structure function F 2 γ has been measured at average Q 2 values of 73 and 390 GeV 2 using data collected by the AMY detector at the TRISTAN e + e − collider. F 2 γ is observed to be increasing as ln Q 2 . The x -dependence of F 2 γ , where x is the momentum fraction carried by the parton inside the photon, is also measured. The measurements are compared with several parton density models.

6Li(γ, t)3He and 6Li(γ, pd)3H Reactions

The nuclear emulsions loaded with 6 Li were irradiated with 32 MeV bremsstrahlung X-rays. A clear discrimination of the reactions was made by the use of a momentum balance method. The 6 Li(γ, t ) 3 He cross section shows a peak at E γ ≃21 MeV with the maximum value 5.1 mb. The angular distribution of phototritons corresponding to the peak energy shows an asymmetry around 90°, indicating an interference between E 1 and E 2 absorptions. The 6 Li(γ, p d ) 3 H cross section has the maximum value 5.8 mb at E γ =24∼25 MeV. The cross sections of these reactions integrated up to 32 MeV are 12.8±1.9 mb·MeV and 18.2±2.0 mb·MeV, respectively. They make the total integrated photon absorption cross section to have a reasonable value expected from the E 1 sum rule. Present data are compared with the predictions of the models for 6 Li proposed so far.

Search for Proton Decay via

We have searched for proton decay via p→νK+ using Super-Kamiokande data from April 1996 to February 2013, 260 kiloton•year exposure in total. No evidence for this proton decay mode is found. A lower limit of the proton lifetime is set to τ/B(p→νK+)>5.9×1033 years at 90% confidence level.