1. 森 隆志 (名古屋大学) 関西中部地方 B中間子の物理実験研究会@奈良女子大学 2009年11月5日
大学activity: 粒子識別
森 隆志 (名古屋大学)
関西中部地方
2009年11月5日

2. 関西中部地方B中間子の物理研究会@奈良女子大学
Contents
Introduction
R&D of TOP counter components
Performance test of prototype
R&D of HAPD for A-RICH counter
Summary
Nov 5, 2009

3. 関西中部地方B中間子の物理研究会@奈良女子大学
1. Introduction
Nov 5, 2009

4. 関西中部地方B中間子の物理研究会@奈良女子大学
1. Our Motivation
Upgrade of Belle PID system
Current PID system of Belle
π/K – separation power : 3σ
Current system
Barrel: TOF + ACC
End cap: ACC
Target Performance
3σ ⇒ 4σ (0.6 < p < 4 GeV/c)
(ACC: Threshold type
Aerogel Cherenkov Counter)
Upgrade
2.6m
1.2m e-
8.0GeV e+
3.5GeV
1.5T
Forward
Backward
Install here
Belle-II
Barrel: TOP counter
End cap: Aerogel RICH
名古屋大学が中心になって
行っている研究について紹介する
Nov 5, 2009

5. 2. Principle of TOP counter (1)
Imaging with quartz
DIRC(Detection of Internally Reflected Cherenkov light) technique
Cherenkov radiator + screen (photo-detector matrix)
Cherenkov light propagate to terminal of quartz with total reflection
Ring image is detect as parabola
For same momentum,
velocity β of π/K is different
different ring images
Require large screen
Nov 5, 2009

6. 2. Principle of TOP counter (2)
TOP(Time Of Propagation) counter
Cherenkov radiator + time sensitive screen
Position (x, y) ⇒ Position + time (x, t)
Very compact & simple
1.18m
TOP
time includes TOF information
TOF y
TOP counter measures
TOF + RICH z x
High performance expected!
Nov 5, 2009

7. 3. Expected Performance in Belle-II
π/K separation power
4σ for 2<p<4
Expected performance
cosθ
Forward
Backward
cosθ
Nov 5, 2009

8. 4. Typical Ring image & Key Parameters
Top view
~1000mm z
400mm x
π/K t x
~100ps
Detection position & time
Typical ring image
Key points
Accuracy of quartz radiator ( = lightguide)
Cherenkov light should propagate without distortion and attenuation
Time resolution and sensitivity of photo-detector
To obtain clear ring image
Important parameters : Ndet,
Nov 5, 2009

9. 5. Requirements to Components
Quartz radiator
Propagate Cherenkov light without distortion
Flatness : < 100μm
Right angle accuracy : ~10”
Total reflection for suppression of attenuation
Surface roughness : 5Å
Photo-detector
Single photon detection
Gain : ～1.0 ×106
Important factor of time resolution of TOP counter
TTS : σphotodetector < 40ps
Number of detected photon : ～20
QE :
Usable in magnetic field of 1.5T for Belle-II
Nov 5, 2009

10. 2. R&D of TOP Counter Components
Nov 5, 2009

11. 関西中部地方B中間子の物理研究会@奈良女子大学
1. Surface Test of Quartz
mirror
single photon
collimator
MCP-PMT
prism
single photon
TTS for each incidence point
prism
line ①
line ②
line ③
TTS[ps]
MCP-PMT
quartz
・407nm pulse laser
・Single photon irradiation
・47.2°incidence
propagation length[mm]
no degradation of TTS
⇒ sufficiently small roughness
Nov 5, 2009

12. 関西中部地方B中間子の物理研究会@奈良女子大学
2. Photo-detector
Requirements
Gain : 1.0×106
TTS : <40ps
QE :
Usable in B -field
Square type MCP-PMT
Co-development
with Hamamatsu Photonics
Only photo-detector
satisfies requirements
MCP-PMT
(Micro Channel Plate)
Channel
~400m
~10m
Channel φ~10μm, Bias angle of MCP : 13°
Usable in B-field
Nov 5, 2009

13. 関西中部地方B中間子の物理研究会@奈良女子大学
3. MCP-PMT R&D
Output charge distribution
Pedestal
Output of single photon
Gain ～ 1.0×106
Single photon detection OK
Nov 5, 2009

14. 関西中部地方B中間子の物理研究会@奈良女子大学
4. MCP-PMT R&D
Single photon irradiation
検出時間分布
counts
QE[%]
σ=34.2±0.4ps
transit time [25ps]
wavelength [nm]
TTS＜40ps OK OK
Nov 5, 2009

15. 3. Performance test of prototype
Nov 5, 2009

16. 関西中部地方B中間子の物理研究会@奈良女子大学
1. Beam Test
Performed in Jun. & Dec. 2008
Items to confirm
Detection of ring image
Obtain N(), number of detected photons par track
TTS measurement
Setup of beam test at Fuji test beam line
electron beam
（2GeV/c）
MCP-PMT
Timing
Counter
MWPC2
MWPC1
Veto counter
Trigger
TOP
Subtract em-shower events
Beam trajectory
t0 determination
Nov 5, 2009

17. 関西中部地方B中間子の物理研究会@奈良女子大学
2. Result : ring image
Ring image (data)
Ring image （simulation） ① ② ④ ③
transit time[25ps]
transit time[25ps] ch ch
Proper action of total system of TOP counter is confirmed
Nov 5, 2009

18. 3. Result : number of detected photons
Number of detected photons/events
arbitrary
N(γ) consistency confirmed
Slightly different ⇒ remaining shower event
Nov 5, 2009

19. 4. Result : transit time distribution
data
simulation
1st
2nd
3rd
1st
2nd
3rd
カウント数
[photons]
ch29
transit time[25ps]
transit time[25ps]
TTS（1st peak）
Data
76.0±2.0 [ps]
Simulation
77.7±2.3 [ps]
Beam irradiation point
(875mm)
875mm
915mm
quartz
3rd
2nd
1st
We confirmed consistency of transit time distributions for beam test & simulation
Nov 5, 2009

20. 関西中部地方B中間子の物理研究会@奈良女子大学
2.6m
1.2m e-
8.0GeV e+
3.5GeV
1.5T
Forward
Backward
Aerogel RICH
4. R&D of hapd for A-RICH
Nov 5, 2009

21. 関西中部地方B中間子の物理研究会@奈良女子大学
1. Aerogel RICH counter
Nov 5, 2009

22. 関西中部地方B中間子の物理研究会@奈良女子大学
2. HAPD R&D
73mm
Photo-detection in Magnetic field
Single photon irradiation
Hybrid structure
Vacuum tube
APD (5x5mm2 matrix)
Bialkali photocathode
~104 total gain
Confirmed
Single photon detection
Available in 1.5T B-field
Current issue
Radiation hardness (neutron) study
Photocathode study
Nov 5, 2009

23. 関西中部地方B中間子の物理研究会@奈良女子大学
5. Summary & Issues
Our Motivation: upgrade of PID system
Target performance: separation power 3σ⇒4σ
Idea: barrel ⇒ TOP, end cap ⇒ Aerogel RICH
TOP counter
New idea of RICH: Position(x, y) Position(x) + time(=TOF+RICH)
Basic performances are confirmed with prototype
Issue
Structure, reconstruction code, lifetime of PMT, readout, etc…
HAPD R&D
Performances are available for ARICH
Neutron hardness, high QE photocathode study
Nov 5, 2009

24. 関西中部地方B中間子の物理研究会@奈良女子大学
Backup
Nov 5, 2009

25. 関西中部地方B中間子の物理研究会@奈良女子大学
Belle-II experiment
Belle detector
e+e- asymmetric collider
e+ : 3.5GeV
e- : 8.0GeV
e+e- → Υ(4S) → BB
π/K-ID is important for flavor tagging
Our target of development : Belle-II experiment
Higher statistics： Higher luminosity ×~40
B-factory
⇒Super B-factory ＆
Higher accuracy ： Belle detector upgrade
Nov 5, 2009

26. 関西中部地方B中間子の物理研究会@奈良女子大学
History of R&D
Butterfly TOP
Nov 5, 2009

27. Performance Parameterization
Separation power :
: Difference of TOF +TOP for π/K（～ 60ps）
timing 1m
assumption
: Detected photons/track（～20）
: TTS of TOP counter
: TTS of photo-detector（～40ps）
: Chromatic dispersion
（1m propagation in quartz: ～50ps　⇒　25ps）
Can suppress with λ cut filter
Important parameters : Ndet, σphotodetector
Nov 5, 2009

28. Chromatic Dispersion Chromatic dispersion Restricts TOP TTS
wavelength [nm]
number of detected photons
Typical wavelength distribution
of detected photons
Typical wavelength distribution
of group velocity of light
group velocity of light [m/ns]
wavelength [nm]
Restricts TOP TTS
This is because refraction index has wavelength dependence
Nov 5, 2009

29. Suppression of Chromatic Dispersion
Wavelength cut
Suppression of chromatic dispersion
with 350nm wavelength cut filter
350nm
Group velocity
of light
σchromatic 50
25ps
Number of
Cherenkov photons
wavelength cut ⇒ TTS improve
Transmittance of
wavelength cut filter ⇒
fine tune
Ndet decrease
Nov 5, 2009

30. 関西中部地方B中間子の物理研究会@奈良女子大学
1. Radiator
Quartz (fused silica)
Size ： 915×400×20 (mm3)‏
Weight ：16kg
Flatness ： < 1.2μm/m
Surface roughness ：5Å
Refractive index ：1.45
Co-development with Okamotokougaku
Nov 5, 2009

31. Construction of Prototype
Al honeycomb
Quartz
Spring loaded polyathetal head plunger×40/surface
Distortion of frame is absorbed by spring
Cross section of radiator part
23mm
46 mm
Al honeycomb support
Core density：0.037g/cm3
Thickness ： 10mm
Surface plate ： 0.3mm Al
Sag ：δ < 80μm
Quartz flatness in Frame
<100μm/m (Measured)
PMT array with λ cut filter
Schematic side view of PMT array
Readout-box
PMT
Joint of 2 parts
Optical contact :
silicon oil + pressure
Nov 5, 2009

32. 関西中部地方B中間子の物理研究会@奈良女子大学
PMT module
HV divider + AMP + Discriminator
Small size (28mmW)
Prototype
Fast AMP (MMIC, 1GHz, x20)
Fast comparator (180ps propagation)
CFD with pattern delay
Performance
Test pulse
~5ps resolution
MCP-PMT
s<40ps
Working well
AMP+CFD
comparator
amp
input
low voltage supply
to TDC
to ADC
Nov 5, 2009

33. 2. Performance Confirmation by Beam Test
Items to confirm
Detection of the ring image of the Cherenkov light
Obtain N(), the number of detected photons par track
Measure the TTS
MC simulation
Ring image
Number of detected photons
Ndet = 16
TTS for 1st surface of ring image
= 78 [ps]
transit time[25ps] ch
Demonstration of the TOP counter with MCP-PMT array
Nov 5, 2009

34. 関西中部地方B中間子の物理研究会@奈良女子大学
Set up for Beam Test
Quartz + MCP-PMT
Fuji test beam line
at KEK
TOP
Counter
MWPC② y y
electron beam
（2GeV/c） x
Timing
Counter
Trigger
Counter x
MWPC①
Beam trajectory
MCP-PMT
Veto counter
t0 determination
Subtract em-shower events
Nov 5, 2009

35. 関西中部地方B中間子の物理研究会@奈良女子大学
σ=13.4±0.7ps
transit time[25ps]
counts
TTS of timing counter
Nov 5, 2009

36. 関西中部地方B中間子の物理研究会@奈良女子大学
伝播距離によって時間分解能はどれだけ悪化するか？
波長分散効果を考慮した理解は正しいのか？
シミュレーション
時間分解能[ps]
伝播距離 [mm]
各伝播距離における測定結果が
シミュレーションを再現
波長分散効果が予想通り
のものであることを確認
Nov 5, 2009

37. 関西中部地方B中間子の物理研究会@奈良女子大学
Nov 5, 2009

38. Summary for TOP Counter
TOP counter is very compact & simple detector based on TOF + RICH technique
Radiator propagates Cherenkov light without distortion
Position(x, y) Position(x) + time (= TOF + TOP)
Target performance of TOP counter
>4σ for 0.6 < p < 4GeV/c
Key parameters
Number of detected photons
Prototype of TOP counter has been constructed
We confirmed basic performances of prototype with following parameters:
Quartz
MCP-PMT
Flatness : 1.2 μm/m
Gain : ~1.0 × 106
Roughness : 5Å
TTS : < 40ps
Shape accuracy : 10”
QE : > 400nm
Nov 5, 2009

39. 関西中部地方B中間子の物理研究会@奈良女子大学
Nov 5, 2009