Author/Authors :
Doroshenko، نويسنده , , M. and Abe، نويسنده , , K. and Ahn، نويسنده , , J.K. and Akune، نويسنده , , Y. and Baranov، نويسنده , , V. and Fujioka، نويسنده , , Y. and Hsiung، نويسنده , , Y.B. and Ikei، نويسنده , , T. and Inagaki، نويسنده , , T. and Ishibashi، نويسنده , , S. and Ishii، نويسنده , , H. and IWATA، نويسنده , , T. and Kobayashi، نويسنده , , S. and Komatsu، نويسنده , , S. and Komatsubara، نويسنده , , T.K. and Kurilin، نويسنده , , A. and ، نويسنده ,
Abstract :
An electromagnetic calorimeter consisting of 576 undoped CsI crystals has been used to search for the K L 0 → π 0 ν ν ¯ decay at the KEK 12-GeV proton synchrotron (E391a). The calorimeter is placed in a vacuum of lower than 10−1 Pa. Special energy and timing calibrations have been performed. The energy calibration started from a check of the linearity for nine sample crystals using an electron beam. Then, after mounting all crystals in the E391a detector, we made an in situ calibration of the energy by using cosmic ray and punch-through muons. The gain constants obtained from both muons agree with each other with an accuracy of 2% ( σ ) . They were further refined by using γγ samples from π0ʹs produced off an aluminum plate (5-mm thick) hit by neutral beam particles. Using the final gain constants, we obtained a K L 0 mass resolution of 4.3 MeV/c2 ( σ ) for the K L 0 → π 0 π 0 π 0 decay. Also, using the timing constants measured for cosmic rays, we obtained a resolution of 0.51 ns ( σ ) for the timing difference among six γʹs in the K L 0 → π 0 π 0 π 0 decay.
Keywords :
Timing calibration , CsI calorimeter , Energy calibration , K L 0 decay
