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Radiator study statusY. Horii, Y. Koga, N. Kiribe, (Nagoya University, Japan)1B2GM, 6th JulyIntroduction2Performance of TOP shown in TDR

Problem arising from the beam test in 2010:

Very effective for many modes including K/pwhile it is challenging to achieve this performance.(M. Thesis by Y. Arita)difference of the time distributions from TDCbetween simulation and data.

SimulationDataTimeTimeRadiator study is important for investigating the reason.Radiators3Radiator for beam test in 2010Two 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 Okamotoand one Corning-7980 bar polished by Zygo.Mirror and wedge will also be glued.gluegluemirrorAlready glued and there are restrictions for the checksWill receive the Suprasil-P710 in the middle of July.mirrorwedgeToday we will show the status of the quality check for the Corning-7980.Suprasil-P20Suprasil-P20Suprasil-P710Corning-7980Photon paths and their effects4Position difference~ 1mmTime difference~ 1 mm / c ~ 3 psecPMTresolution: ~40 psecchannel size: ~5 x 5 mm2Striae and surface non-flatness of quartz and mirrorcould change the paths of the photons.If this change is large compared to the PMT SPEC,effect on the K/p separation could be significant.

1 mrad change at ~1m before arriving at PMT produces

Finally we need to estimate the effect by the simulationbut at least the variance of O(0.1) mrad will be safe.Check of the photon paths5Laser (405 nm)Data taken by CCD.

Example of the images at the CCD:Bit map file is transferred toa histogram and fitted with2-D Gaussian (signal)+ 2-D linear function (BG).

DataFitted PDFStriae and surface non-flatness effecton position and size of the spot.Only Blue is used from RGB.Check of the photon paths6Scanned incident points at x=2.5 cm.xyLaserCCDy [mm]y [mm]y [mm]y [mm]sy [mm]my [mm]sx [mm]mx [mm]y >15 mm: through air.y