TOP counteroverview and issues
K. Inami (Nagoya university)
2008/7/3-4 2nd open meeting for proto-collaboration
- Overview- Design- Performance
- Prototype construction- Summary
2008/7/3-4 2nd open meeting for proto-collaboration 2
Side view of Super Belle detector
2.6m
1.2m
e-
8.0GeVe+
3.5GeV
1.5T
Introduction TOP (Time Of Propagation) counter
Developing to upgrade the barrel PID detector For Super B factory
Lpeak~1035~36/cm2/s, 20~100 times higher than present Need to work with high beam BG
To improve K/ separation power Physics analysis
B/K, , K etc. Flavor tag Full reconstruction
Target; 4 for 4 GeV/c
2008/7/3-4 2nd open meeting for proto-collaboration 3
TOP counter Cherenkov ring in quartz bar
Reconstruct ring image using ~20 photons on the screen reflected inside the quartz radiator as a DIRC.
Photons are detected with photon detectors.
Different ring image for the pion and kaon of the same momentum
Need large screen...
2008/7/3-4 2nd open meeting for proto-collaboration 4
TOP counter 2D position information Position+Time
Compact detector!
Linear array PMT (~5mm)Time resolution ~40ps
~2m
K
Simulation2GeV/c, =90 deg.
~200ps
Different opening angle for the same momentum Different propagation length(= propagation time)
+ TOF from IP works additively.
2008/7/3-4 2nd open meeting for proto-collaboration 5
Baseline design Quartz: 255cmL x 40cmW x 2cmT
Focus mirror at 47.8deg. to reduce chromatic dispersion
Multi-anode (GaAsP p.c.) MCP-PMT Linear array (5mm pitch), Good time resolution (<~40ps) Measure Cherenkov ring image with timing information
MCP-PMT
TTS~35ps
2008/7/3-4 2nd open meeting for proto-collaboration 6
Chromatic dispersion
GaAsP photo-cathode Higher quantum-efficiency at longer wavelength → less chromatic error
Multi-alkali p.c. + cut filter (option)
Light propagation velocity inside quartz
Photon sensitivity at longer wavelength shows the smaller velocity fluctuation.
Variation of propagation velocity depending on the wavelength of Cherenkov photons
2008/7/3-4 2nd open meeting for proto-collaboration 7
Focusing TOP Remaining chromatic effect makes ~1
00ps fluctuation for TOP. Use dependence of Cherenkov angle
to correct chromaticity Focusing system to measure c
c y position Reconstruct ring image from 3D info
rmation (time, x and y).
Focus Mirror
))(
1(cos=)( 1
βλnλθ c
ー
Side view
Mirror image
2008/7/3-4 2nd open meeting for proto-collaboration 8
Focusing TOP (2) c~12mrad over sensitive range y~20mm (~quartz thickness)
We can measure dependence and obtaingood separation even with narrow mirror and readout plane, because of long propagation length.
Not need focusing block Not need fine readout channels
1850mm
Virtual readout screen 22mm x 5mm matrix
Focusing mirror
c~12mrad
2008/7/3-4 2nd open meeting for proto-collaboration 9
Performance Focusing type + GaAsP photo-cathode
>400nm filter, Correction Eff.=35%
4.2 K/ for 4 GeV/c, =70 ゚
2008/7/3-4 2nd open meeting for proto-collaboration 10
TOP module
A module supporting quartz and PMT Quartz radiator
Support by aluminum honeycomb box Black box
MCP-PMT Assemble with front-end elec. Connect elec. part to honeycomb
Not glue PMT with quartz Prototype construction
1st step) quartz 1m (forward, backward part) By the end of June Beam test
2nd step) quartz 2m + focus mirror By the end of December
2008/7/3-4 2nd open meeting for proto-collaboration 11
Quartz radiator Size; 915 x 400 x 20 mm Flatness; <2m Roughness; <0.5nm
By Okamoto optics work, inc.
Support by Aluminum honeycomb panel
1cm thickness With plungers
Keep quartz in air ~1kg/plunger on
honeycomb ~2.5kg/plunger on side
panel
2008/7/3-4 2nd open meeting for proto-collaboration 12
Focusing mirror Spherical mirror (R=5m)
Check peak position of spherical mirror wrt. quartz edge
By 3D measurement system at Nagoya univ.
0.33±0.30±0.20mm outside from bar edge
Acceptable in simulation
Cross check by interferometer in Okamoto optics work, inc.
Pin gaugePin gaugeMirrorMirror
LensLens
Focusing mirror
2cm
40cm
Spherical mirror (R=5m)
2008/7/3-4 2nd open meeting for proto-collaboration 13
PMT box MCP-PMT
27.5x27.5 mm square By Hamamatsu photonics
Multi-alkali p.c. beam test GaAsP p.c. lifetime test
PMT module HV divider AMP + CFD
No CFD part for beam test PMT box
13 modules <40ps TTS for single photon Support modules and filters Attach to quartz box
2008/7/3-4 2nd open meeting for proto-collaboration 14
Photon detector; main issue Photo-cathodes of MCP-PMT
Multi-alkali (bi-alkali); OK. Almost established production Confirmed enough lifetime
GaAsP; in progress Better efficiency at longer wavelength Need more production R&D and lifetim
e test Multi-alkali without Al protection la
yer on MCP (option) 4 /K separation for 4GeV/c Improved efficiency (x1.6) Almost established production, but ne
ed some modification to improve lifetime (3-layer MCP, operation with lower gain, etc.) Al layer
2008/7/3-4 2nd open meeting for proto-collaboration 15
Summary Baseline design
Focusing system To correct Chromatic effect with narrow mirror (20mmt)
GaAsP photo-cathode MCP-PMT Prototype shows the enough performance
TTS = 35ps for single photon, High Q.E. (>40% at 500nm) Performance; >4 for 4GeV/c
Prototype construction is in progress. Quartz bar + support structure Focusing mirror Need to measure the TOP performance MCP-PMT + front-end elec.
Issues MCP-PMT; Need better photon efficiency Need help,
DAQ electronics (high precision TDC; ~10ps) Structure construction, Software, ...
2008/7/3-4 2nd open meeting for proto-collaboration 16
Test counterTest counterBeam test
@ KEK PS 2 line 3 GeV/c beamin=in=90 degree
• Clear ring image
• Reasonable time
resolution• Enough bar quality
1mm pitch readout
2008/7/3-4 2nd open meeting for proto-collaboration 17
Geometry
18 counters in r-
Al wall (1mmt)
Quartz
10% dead space in Maybe need to be overlapped layout
Need to locate support structure in narrow space
~20mm between quartz and outer structure
Overlapped layout
2008/7/3-4 2nd open meeting for proto-collaboration 18
Performance Focusing type + Multi-alkali
>350nm filter, Correction Eff.=60%
3.5 K/ for 3 GeV/c, =70 ゚
Because of complicated ring image
2008/7/3-4 2nd open meeting for proto-collaboration 19
TOP configuration summary
Focusing type can reduce the dead space and remove middle PMT.
optionK/pi separation
performance at 70 deg, 4GeV/c
issues
3 readout + multi-alkali 2.8 sigma
(Make prototype)
3 readout + GaAsP 3.5 sigma
PMT productionPMT lifetime
Focusing + multi-alkali
2.5 sigma 4.0 sigma if improved eff.
PMT lifetime
Focusing + GaAsP 4.2 sigma
PMT productionPMT lifetime