Blair Ratcliff 5 th SuperB Workshop, Paris May 2007 1 PID Related R&D at SLAC: PID Related R&D at SLAC: The Focusing DIRC and a The Focusing DIRC and a Fast TOF Using Cherenkov Fast TOF Using Cherenkov Light. Light. Blair Ratcliff Blair Ratcliff Representing: I. Bedajanek, J Benitez, D.W.G.S. Leith, G. Mazaheri, J. Schwiening, K. Suzuki, J. Uher, J. Va’vra.
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Blair Ratcliff5 th SuperB Workshop, Paris May 2007 1 PID Related R&D at SLAC: The Focusing DIRC and a Fast TOF Using Cherenkov Light. Blair Ratcliff Blair.
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Blair Ratcliff5th SuperB Workshop, Paris May 20071
PID Related R&D at SLAC: PID Related R&D at SLAC: The Focusing DIRC and a The Focusing DIRC and a
Fast TOF Using Cherenkov Fast TOF Using Cherenkov Light. Light.
Blair RatcliffBlair Ratcliff
Representing: I. Bedajanek, J Benitez, D.W.G.S. Leith, G. Mazaheri, J. Schwiening, K. Suzuki, J. Uher, J. Va’vra.
Blair Ratcliff5th SuperB Workshop, Paris May 20072
Focusing DIRC Prototype GoalsFocusing DIRC Prototype GoalsWork with manufacturers to develop and characterize one or more fast, pixelated photon detectors including;
• basic issues such as cross talk, tube lifetime, and absolute efficiency• operation in 15 KG field
Measure single photon Cherenkov angular resolution in a test beam• use a prototype with a small expansion region and mirror focusing, instrumented with a
a number of candidate pixelated photon detectors and fast (25 ps) timing electronics Much lower background sensitivity with somewhat improved performance parameters • demonstrate correction of chromatic production error via precise single photon timing• demonstrate that the performance with mirror focusing is as expected.• measure N0 and timing performance of candidate detectors.
Blair Ratcliff5th SuperB Workshop, Paris May 20073
Radiator• 3.7m-long bar made from three spare high-quality
BABAR-DIRC barsExpansion region
• coupled to radiator bar with small fused silica block• filled with mineral oil (KamLand experiment) to match
fused silica refractive index • include optical fiber for electronics calibration• would ultimately like to used solid fused silica block
Focusing optics• spherical mirror from SLD-CRID detector (focal length 49.2cm)
Photon detector• placed in fixed slots allowing easy replacement.• typically using 2 Hamamatsu flat panel PMTs and 3 Burle MCP-PMTs in focal plane• readout to CAMAC/VME electronics with 25 ps resolution. Limited number of channels available.
Blair Ratcliff5th SuperB Workshop, Paris May 20074
Nucl.Inst.&Meth., A 553 (2005) 96Nucl.Inst.&Meth., A 553 (2005) 96
TTiming iming resolutions resolutions were were obtained obtained using a fast using a fast laser diode laser diode in bench in bench tests with tests with single single photons on photons on pad center.pad center.
Cherenkov Photons In Time & Pixel DomainsCherenkov Photons In Time & Pixel Domains
Blair Ratcliff5th SuperB Workshop, Paris May 20077
Cherenkov angle production Cherenkov angle production controlled by controlled by nnphasephase (cos (cos cc = 1/(n = 1/(nphasephase:: c c (red)(red) < < c c (blue)(blue)Propagation of photons Propagation of photons is controlled by is controlled by nngroupgroup (v(vgroupgroup = = cc0 0 /n/ngroupgroup = c = c0 0 /[n/[nphasephase - - phasephase):): vvgroupgroup(red)(red) > > vvgroup group (blue)(blue)
Principle ofchromaticcorrectionby timing:
TOP = time ofpropagationof photonin the bar
TOP/Lpath = 1/vgroup()
The DIRC as a SpectrometerThe DIRC as a Spectrometer
Blair Ratcliff5th SuperB Workshop, Paris May 20078
ll detectors: PMT with 3mm pixels only:
Structure in the Structure in the uncorrecteduncorrected distributions are caused by the coarse pixelization and the finite distributions are caused by the coarse pixelization and the finite beam phase space. The time correction smears this effect away. beam phase space. The time correction smears this effect away.
Smaller radial pixel size (3mm) helps to improve the Cherenkov angle resolution as expected.Smaller radial pixel size (3mm) helps to improve the Cherenkov angle resolution as expected.
Correction off: Correction off:Correction on:
~ 5.0 mrad
~ 5.1 mrad
Chrom
+Pixel
Correction off: Correction off:Correction on:Correction on:
~ 5.0 mrad
~ 5.1 mrad
Chrom
+Pixel
Resolution Improvement with Chromatic CorrectionResolution Improvement with Chromatic Correction
Blair Ratcliff5th SuperB Workshop, Paris May 20079
Main contributions to the Main contributions to the cc resolution:resolution:
- - optical aberrations of this particular designoptical aberrations of this particular design: : grows from 0 mrad at ring center to 9 mrad in outer wings of Cherenkov ringgrows from 0 mrad at ring center to 9 mrad in outer wings of Cherenkov ring
c resolution - all pixels: c resolution - 3mm pixels only:
Data / GEANT 4 MC ComparisonData / GEANT 4 MC Comparison
Blair Ratcliff5th SuperB Workshop, Paris May 200710
Prototype’s Prototype’s Npe_measured Npe_measured andand Npe_expected Npe_expected are consistent are consistent withinwithin ~20%. ~20%.
Hamamatsu H-9500 Hamamatsu H-9500 MaPMTsMaPMTs: :
We expectWe expect No No ~ 31 cm~ 31 cm-1-1, which , which in turn givesin turn gives Npe ~ 28 Npe ~ 28 for 1.7 for 1.7 cm fused silica bar thickness, cm fused silica bar thickness, and somewhat better and somewhat better performance in performance in pi/Kpi/K separation separation than the present BaBar DIRC. than the present BaBar DIRC.
Burle-Photonis MCP-PMT:Burle-Photonis MCP-PMT:
We expect We expect NoNo ~ 22 cm~ 22 cm-1-1 and and Npe ~ 20Npe ~ 20 for B = 0kG. for B = 0kG.
Blair Ratcliff5th SuperB Workshop, Paris May 200713
Single Photon Timing Resolution (Single Photon Timing Resolution (TTSTTS))
10 10 m MCP hole diameterm MCP hole diameter B = 0 kGB = 0 kG 64 pixel devices, pad size: 6 mm x 6 mm.64 pixel devices, pad size: 6 mm x 6 mm. Phillips CFDPhillips CFD PiLas red laser diode operating in the PiLas red laser diode operating in the
Ortec VT120A amplifier ~0.4 GHz BW, 200x gain + 6dB
Fit: g + g
Burle/Photonis MCP-PMT 85012-501 (ground all pads except one)
Fit: g + g
Hamamatsu C5594-44 amplifier 1.5 GHz BW, 63x gain
Blair Ratcliff5th SuperB Workshop, Paris May 200714
Bench Tests With Fast Time DigitizationBench Tests With Fast Time Digitization
Detector
Laser diode
Control unit
PiLas
PiLas ~15 ps/Npe
Trigger
TTL
NIM
Disc
PiLas_trigger ~?
Pulser
START
STOP
14 bitADC 114
TAC 566
Pulser + TAC_ADC ~ 3.2 ps
(My measurement)
Fiber ~?
Delay ~?
MCP-PMT
= {MCP-PMT+
Fiber + Amp_CFD +
Delay +
PiLas + Pulser+TAC_ADC +
PiLas_trigger}
+ Systematic effects: laser & temperature drifts, ground loops, etc.
Pulser_TAC_ADC
~ 3.2 ps
Ortec 9236 Amp/CFD
Amp_CFD ~ 6 -7 ps (Manufacturer)
Manufacturer My measurement
Blair Ratcliff5th SuperB Workshop, Paris May 200715
Timing Resolution Versus Npe for different R/OTiming Resolution Versus Npe for different R/O
Npe = 50-60 for 1cm-thick Quartz radiator + window & with Burle Bialkali Npe = 50-60 for 1cm-thick Quartz radiator + window & with Burle Bialkali QE.QE.
< 15 ps seems feasible.< 15 ps seems feasible. The Ortec 9327-like performance is adequate. The Ortec 9327-like performance is adequate.
Blair Ratcliff5th SuperB Workshop, Paris May 200716
SummarySummary Pixelated Photon detectors continue to be improved by manufacturers. The performance
expected from a small SOB DIRC with a MaPMT H-9500 tube should be similar to the BaBar DIRC in Npe with ~ 20% better resolution with the 3 mm pixels. Need to continue to work with manufactures in order to improve the photon detectors.
We have demonstrated the principle of chromatic correction to the Cherenkov angle using timing.
Bench tests of fast timing PMTs are encouraging to date. Best results with the laser diode:Best results with the laser diode:
- - ~ ~ 12 ps for Npe = 50-60 (as expected from 1cm thick Cherenkov radiator)12 ps for Npe = 50-60 (as expected from 1cm thick Cherenkov radiator)..
- - TTS TTS < 26 ps for Npe ~ 1< 26 ps for Npe ~ 1..- - Upper limit on the MCP-PMT contributionUpper limit on the MCP-PMT contribution: : MCP-PMT MCP-PMT < 6.5 ps< 6.5 ps..
- - TAC/ADC contribution to timingTAC/ADC contribution to timing:: TAC_ADC TAC_ADC < 3.2 ps< 3.2 ps..
- - Total electronics contribution at present:Total electronics contribution at present: Total_electronicsTotal_electronics~ 7.2 ps~ 7.2 ps..
More to come soon….We hope to continue Fast DIRC detector work and confirm TOF performance in a test beam run this year….However, the future of test beams at SLAC is quite uncertain.
Blair Ratcliff5th SuperB Workshop, Paris May 200717
Burle 85011-501 MCP-PMT• bialkali photocathode• 25μm pore MCP• gain ~5×105
Refractive Indices and Dispersion versus Wavelength for SiO2
1.4
1.5
1.6
1.7
1.8
1.9
2
0.25 0.3 0.35 0.4 0.45 0.5 0.55 0.6 0.65 0.7
Photon Wavelength (microns)
Refra
ctiv
e In
dex
0.01
0.1
1
10
Disp
ersi
on, -
dn/d
n(phase) n (group)
Dispersion [n (phase)] Dispersion [n (group)]
Dispersion [n (group)]/ Dispersion [n (phase)]
Blair Ratcliff5th SuperB Workshop, Paris May 200725
ReconstructionReconstruction
Precisely measured detector pixel coordinates and beam parameters.→ Pixel with hit (xdet, ydet, thit) defines 3D propagation vector in bar
and Cherenkov photon properties (assuming average ) x, y, cos cos cos Lpath, nbounces, c, c , tpropagation
Blair Ratcliff5th SuperB Workshop, Paris May 200726
PID Software R&D Studies are NeededPID Software R&D Studies are Needed
• Need high quality physics MC simulations to demonstrate need for detector upgrades base-lined. (Realism is important , not only for PID simulation (both ID and Mis-ID rates), but also for interactions in material, tracking, CAL performance, etc.)
• Will need to be able to study physics tradeoffs between an added PID device and other detector systems.
• Is a separate system necessary or should dE/dx be revisited?
• Need specific physics channels that demonstrate compelling need for forward PID.
• Geometrical coverage plus momentum range: In particular, are there important physics channels that would benefit from enhanced PID momentum coverage range?