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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