Slide 1

Radiator study status Y. Horii, Y. Koga, N. Kiribe, (Nagoya University, Japan) 1 B2GM, 6 th July

Slide 2

Introduction 2 Performance of TOP shown in TDR Problem arising from the beam test in 2010: Very effective for many modes including K / while it is challenging to achieve this performance. (M. Thesis by Y. Arita) difference of the time distributions from TDC between simulation and data. Simulation Data Time Radiator study is important for investigating the reason.

Slide 3

Radiators 3 Radiator for beam test in 2010 Two Suprasil-P20 bars and mirror, surface polished by Okamoto. Radiator for beam test in 2011 (backup for Belle II TOP?) One Suprasil-P710 bar polished by Okamoto and one Corning-7980 bar polished by Zygo. Mirror and wedge will also be glued. glue mirror Already glued and there are restrictions for the checks Will receive the Suprasil-P710 in the middle of July. mirror wedge Today we will show the status of the quality check for the Corning-7980. Suprasil-P20 Suprasil-P710 Corning-7980

Slide 4

Photon paths and their effects 4 Position difference ~ 1mm Time difference ~ 1 mm / c ~ 3 psec PMT resolution: ~40 psec channel size: ~5 x 5 mm 2 Striae and surface non-flatness of quartz and mirror could change the paths of the photons. If this change is large compared to the PMT SPEC, effect on the K/ separation could be significant. 1 mrad change at ~1m before arriving at PMT produces Finally we need to estimate the effect by the simulation but at least the variance of O(0.1) mrad will be safe.

Slide 5

Check of the photon paths 5 Laser (405 nm) Data taken by CCD. Example of the images at the CCD: Bit map file is transferred to a histogram and fitted with 2-D Gaussian (signal) + 2-D linear function (BG). DataFitted PDF Striae and surface non-flatness effect on position and size of the spot. Only Blue is used from RGB.

Slide 6

Check of the photon paths 6 Scanned incident points at x=2.5 cm. x y Laser CCD y [mm] y [mm] y [mm] x [mm] x [mm] y >15 mm: through air. y