bubble chamber Spark Chamber Cherenkov Radiation Wave front

泡箱（bubble chamber） 過熱液体

Spark Chamber

Cherenkov Radiation チェレンコフ輻射 • Wave front comes out at certain angle • That’s the trivial result!

Belle detector components

Magnetic field generated Iron flex return Non-uniformity below 5% inside tracking volume. Field mapping with 0. 3% precision.

150 mm

X-T relation (drift time vs position) • • • He(50%)-C 2 H 6(50%) B=1. 5 Tesla HV : 2. 3 KV Cell Size: 18 mm Maximum Drift Time : ~400 nsec + + + cell

• Wires – 30 mmf Au-W for sense wire – 126 mmf Al for field wire • Square cells – 16 mm(r)X~18 mm(rf) – 50 layers in total

粒子の識別 Aerogel Cherenkov and To. F

Cherenkov counter チェレンコフ放射は 最低速度制限あり Radiator v>c/n 媒質中の光速 制限速度はｎを選べば 変えられる (c: 光速, 　n: 屈折率) Cherenkov Light Charged Particles Photon sensors

Silica Aerogel Cherenkov radiator Colloidal form of Si. O 2. r=0. 1 g/cc　 n=1. 006 ~ 1. 06 Hydrophobic Fractal structure

Number of photoelectrons K中間子 (v<c/n) 　　　　電子　　　　　 (v~c>c/n) Number of photons

To. F (Time of Flight) 飛行時間測定 • The most direct way to measure the Particle identification velocity of particles. (mc 2)2=E 2(1 -(v/c)2) velocity=flight length/flight time To. F counter Flight length

ガンマ線を捉える （カロリメータ）無機シンチレータの一例 • Total number of crystals = ８，７３６ • Total weight is ~43 ton • 実は一番の金食い虫 barrel (6, 624) r=1. 25 m Backward endcap (960) z~ -1 m e- e+ Forward endcap (1, 152) z~+2 m

Structure of Cs. I counter Preamp. cards Preamp box Cs. I(Tl) crystal ~60 x 300 mm. L (16. 2 X 0) Mother board Photodiodes S 2744 -08 （1 cm x 2 cm） Cs. I counter Aluminized Mylar sheet

余談ながら・・・ ＰＥＴ（Positron Emission　Tomography ）

KLM (KL and m detector) 14 x 47 mmt iron plates (magnetic flux return) 15 RPC super layers Inserted (PID)

RPC super layer India Ink Signal pickup (x) Glass plates 8 k. V Signal pickup (y) +++++++++++++++ _____ __ __ Spacers India Ink The discharge is is induced quenched when An avalanche and A charged particle passes. 2 all of the locallyinto (A~0. 1 cm then develops a spark. ) available charge is consumed. The discharged area recharges slowly through the high-resistivity glass plates.