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Compact, low-power and (deadtimeless) high timing precision
photodetector readoutG. Varner and L. Ruckman [University of Hawaii]
J. Va’vra and J. Schwiening [SLAC]
29-JUN-07
• Progress in expensive PD recording• Precision timing detection• PROMPT concept• T-492 beam test • Next Generation readout concepts
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TDCPerformance
~0.37ns
Comparison: STaR vs. CAMAC y = 1.0174x - 1.3038
R2 = 0.9996
0
10
20
30
40
50
60
0 10 20 30 40 50 60
CAMAC Charge [pC]
ST
aR A
DC
Ch
arg
e [p
C]
Run 1
Linear (Run 1)
QDCPerformance
Inexpensive Options:FPGA based readout
ASIC: ATWD, DRS,others (KamLAND,IceCube, MEG, MAGIC)
J. Instr. 1 P07001 (2006)
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A Different kind of Detector
• 20-30cm vs. 200-800nm (bandwidth 200-1200 MHz)
• Completely solar powered (tight demands on power)
• 324 chan. @ 2.6GSa/s
~320ps
Measured
~7m
Antarctic Impulsive Transient Antenna(ANITA)
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Large Analog Bandwidth Recorder and Digitizer with Ordered Readout [LABRADOR]
8+1 chan. * 256+4 samples
StraightShot
RF inputs
Random access:
• Common STOP acquisition
• 3.2 x 2.9 mm• Conversion in
21s (all 2340 samples)
• Data transfer takes 80s
• Ready for next event in ~50s
• Switched Capacitor Array (SCA)
• Massively parallel Wilkinson ADC array
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LAB3 Architecture Details
• No missing codes• Linearity as good
as can make ramp
• Can bracket
range of interest
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LABRADOR sampling & linearity
• Excellent linearity
• Sampling rates up to 4 GSa/s with voltage overdrive
2.6GSa/s
12-bit ADC
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Bandwidth Evaluation
TransientImpulse
FFTDifference
Frequency [GHz]
f3dB ~> 1.2GHz
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Jiwoo NamUC Irvine
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Finer Calibration600MHz Clock
Estimated Limit
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High Speed sampling
LABRADOR Commercial
Sampling speed
1-3.7 GSa/s 2 GSa/s
Bits/ENOBs 12/9-10 8/7.4
Power/Chan. <= 0.05W 5-10W
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• Good performance, but– CFD not compact, rate dependent (SLAC 16 channel card is 9U)
– High-power, potentially noisy if inside detector
– Buffer depth limitations (already an issue for TOF upgrade)
Precision Timing Recording Options
• Constant Fraction Discriminator + Multi-Hit TDC
Measurements from ALICE-TOFWithout INL compensation
After INL compensation
+
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Exploration DirectionFor high channel counts, prefer to do the measurement at the photodetector (avoids cables which take up space and leads to dispersion for fast timing signals)
• Noise (interference) inside detector• No fast discriminators (power/heat)• Precision timing waveform sampling
• Explore different photo-detectors• Highly integrated detector & electronics
• Lower gain• Magnetic field robustness
• Modular, cost effective in large volumes (Advanced focusing DIRC could be 250,000 channels)
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Precision Timing Motivation (1)
Jerry Va’vra
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Motivation (2) --Chromatic Correction
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Blank slide
Set-up in End Station A at SLAC, where did ANITA calibration
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Blank slide
7 x 64 PMT channels (448 total), not enough SLAC electronics, proposal to instrument some with new electronics (prototyped under DOE Advanced Detector Research award)
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UH Prototype Readout Chain
G = 5x105
single p.e. ~1mV
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64-channel Amplifier Stackbased on RF amplifiers (cheap, high BW)
Within MCPprofile
Ribbon cable (differential analog) output
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Integration Test Results
Raw signal
Scanning Test Set-up:Measured noise ~4mVrmsVoltage Gain ~200High bandwidth
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16 BLAB1 ASICs
Processed hit times via CAMAC Full waveforms over USB2
Differential inputs from amp boards
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Buffered LABRADOR (BLAB1) ASIC
• 64k samples deep
• Multi-MSa/s to Multi-GSa/s
• 12-64us to form Global trigger
3mm x 2.8mm, TSMC 0.25um
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Buffered LABRADOR (BLAB1) ASIC• 10 real bits of dynamic range
Measured Noise
1.4mV
1.8V dynamic range
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BLAB1 Analog Bandwidth
• A few fixes (lower power, higher BW)
• Multi-channel BLAB2 -3dB ~300MHz
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BLAB1 Sampling Speed
200ps/sample Single sample:200/SQRT(12)~ 58ps
But, haveComplete Waveform Information
Can store 13us at 5GSa/s (before wrapping around)
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125MHz sine wave
6GSa/sPre-calibration
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Calibration (1)
Linear variation across chipDue to IR drop in feed voltage(can be improved)
6GSa/s
400MHz sine wave
Storage Cell Number
Ext
ract
ed P
erio
d [n
s]
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Calibration (2)
After basic linearity and bin-by-bin correction~11ps intrinsic (~8ps possible)
6GSa/s
400MHz sine wave
Extracted Period [ns]
15psLinearity only
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Bench Test timing
~27ps for two edges~20ps for each edge
6GSa/s
~30ns pulse pair
~40ps for PMT likeSignals (working on algorithm)
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Temperature Dependence
0.2%/degree C(can correct)
6GSa/sSample aperature (172ps = 5.8GSa/s)
Matches SPICE simulation
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Typical single p.e. signal [Burle]Overshoot/ringing
Due to Higher bandwidth,“warts” of signal appear
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Measured Burle Cross-talk
Raw signal With higher bandwidth, nature of ringing well seen.
By measuring waveforms, some hope to correct
Electronics only: <1% crosstalk
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Interleaved Operation
LARC ASIC: 64 chan @ 5 GSa/s = 384GSa/sStreak camera type applications – ps timing
• Single shot!• uncalibrated• room for improvement• push BW higher
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Vacuum MCP-PMT Issues
• lower Q.E., fill factor• High voltage operation, longevity• High density packing• Magnetic field effects• Irreducible Manufacturing Costs
How to get to a large system?
•SBIR with LightSpin Technologies• Proprietary Solid-State MCP demonstrator (1 x 1024)• No HV, high Q.E. (200 – 900nm!!)• Lower dark count rate than Si-PM• Mate with BLAB variant, determine timing resolution
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f-DIRC Array Concept
Many k Photodetector
channels
SiPMs/APDs
ASIC
Carrier Socket
SingleModule:(side-view)
Tiled Array Readout Board
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• High Precision Timing Results– Initial results promising– No fundamental limit– Practical issues important (T0)
• Plans:– T-492 test of f-DIRC (ESA SLAC)– LARC, BLAB2 ASICs– Direct integration test with MPPC/SS-MCP
• Push PD technology
• Future:– Low-costs in volume – Integrate amplifier for higher gain– Explore limits of analog BW/sampling
Summary
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Backup slide -- cables!
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Blank slide