Search

A spiral fiber tracker (SFT) has been designed and produced for the J-PARC E36 experiment as an element of the tracking system for conducting a high-resolution momentum measurement of charged particles from kaon decays. A novel technique to wind the pre-made fiber ribbons spirally was employed for the configuration with four detector layers made of 1 mm diameter plastic scintillating fibers. Good position alignment and sufficiently high detection efficiency for charged particles with minimum ionizing energy were confirmed in cosmic ray test. The tracker was successfully used in the E36 experiment. [ABSTRACT FROM AUTHOR]

We report a search for d&ast; dibaryon production by double-radiative capture on pionic deuterium. The experiment was conducted at the TRIUMF cyclotron using the RMC cylindrical pair spectrometer, and detected γ-ray coincidences following pion stops in liquid deuterium. We found no evidence for narrow dibaryons, and obtained a branching ratio upper limit, BR<6.7×10−6 (90% C.L.), for narrow d&ast; production in the mass range from 1920 to 1980 MeV. [Copyright &y& Elsevier]

The J-PARC E36 experiment is searching for lepton universality violation with a stopped kaon beam by measuring the ratio of the K + decay widths Γ ( K e 2 ) ∕ Γ ( K μ 2 ) = Γ ( K + → e + ν e ) ∕ Γ ( K + → μ + ν μ ) . Since the radiative K + → e + ν e γ decays are backgrounds to be removed in this measurement, the radiated γ rays were detected in a CsI(Tl) calorimeter. The energy calibration for the 768 CsI(Tl) modules was performed using mono-chromatic μ + s from the K μ 2 decays. The delayed e + signals from the muon decays were required in order to improve the S/N ratio of the K μ 2 peak by suppressing background events. In addition, a new energy calibration method of the CsI(Tl) calorimeter using stopped cosmic muons has been established. [ABSTRACT FROM AUTHOR]

Abstract: We report a search for low-lying exotic baryons via double radiative capture on pionic hydrogen. The data were collected at the TRIUMF cyclotron using the RMC spectrometer by detecting gamma-ray pairs from pion stops in liquid hydrogen. We found no evidence to support an earlier claim for exotic baryons of masses 1004 and , and set upper limits on exotic baryon mediated capture of and , respectively. We also obtained bounds on the couplings between exotic baryons and ordinary nucleons. [Copyright &y& Elsevier]