PD '07 Kobe -- G. Varrner 1 Compact, low-power and (deadtimeless) high timing precision photodetector readout G. 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

PD '07 Kobe -- G. Varrner 2 TDC Performance ~0.37ns QDC Performance Inexpensive Options: FPGA based readout ASIC: ATWD, DRS,others (KamLAND, IceCube, MEG, MAGIC) J. Instr. 1 P07001 (2006)

PD '07 Kobe -- G. Varrner 3 A Different kind of  Detector 20-30cm vs nm (bandwidth MHz) Completely solar powered (tight demands on power) GSa/s ~320ps Measured ~7m Antarctic Impulsive Transient Antenna (ANITA)

PD '07 Kobe -- G. Varrner 4 Large Analog Bandwidth Recorder and Digitizer with Ordered Readout [LABRADOR] 8+1 chan. * samples Straight Shot RF inputs Random access: Common STOP acquisition 3.2 x 2.9 mm Conversion in 21  s (all 2340 samples) Data transfer takes 80  s Ready for next event in ~50  s Switched Capacitor Array (SCA) Massively parallel Wilkinson ADC array

PD '07 Kobe -- G. Varrner 5 LAB3 Architecture Details No missing codes Linearity as good as can make ramp Can bracket range of interest

PD '07 Kobe -- G. Varrner 6 LABRADOR sampling & linearity Excellent linearity Sampling rates up to 4 GSa/s with voltage overdrive 2.6GSa/s 12-bit ADC

PD '07 Kobe -- G. Varrner 7 Bandwidth Evaluation Transient Impulse FFT Difference Frequency [GHz] f 3dB ~> 1.2GHz

PD '07 Kobe -- G. Varrner 8 Jiwoo Nam UC Irvine

PD '07 Kobe -- G. Varrner 9 Finer Calibration 600MHz Clock Estimated Limit

PD '07 Kobe -- G. Varrner 10 High Speed sampling LABRADORCommercial Sampling speed GSa/s2 GSa/s Bits/ENOBs12/9-108/7.4 Power/Chan.<= 0.05W5-10W

PD '07 Kobe -- G. Varrner 11 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-TOF Without INL compensation After INL compensation +

PD '07 Kobe -- G. Varrner 12 Exploration Direction For 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)

PD '07 Kobe -- G. Varrner 13 Precision Timing Motivation (1) Jerry Va’vra

PD '07 Kobe -- G. Varrner 14 Motivation (2) --Chromatic Correction

PD '07 Kobe -- G. Varrner 15 Blank slide Set-up in End Station A at SLAC, where did ANITA calibration

PD '07 Kobe -- G. Varrner 16 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)

PD '07 Kobe -- G. Varrner 17 UH Prototype Readout Chain G = 5x10 5 single p.e. ~1mV

PD '07 Kobe -- G. Varrner channel Amplifier Stack based on RF amplifiers (cheap, high BW) Within MCP profile Ribbon cable (differential analog) output

PD '07 Kobe -- G. Varrner 19 Integration Test Results Raw signal Scanning Test Set-up: Measured noise ~4mVrms Voltage Gain ~200 High bandwidth

PD '07 Kobe -- G. Varrner BLAB1 ASICs Processed hit times via CAMACFull waveforms over USB2 Differential inputs from amp boards

PD '07 Kobe -- G. Varrner 21 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

PD '07 Kobe -- G. Varrner 22 Buffered LABRADOR (BLAB1) ASIC 10 real bits of dynamic range Measured Noise 1.4mV 1.8V dynamic range

PD '07 Kobe -- G. Varrner 23 BLAB1 Analog Bandwidth A few fixes (lower power, higher BW) Multi-channel BLAB2 -3dB ~300MHz

PD '07 Kobe -- G. Varrner 24 BLAB1 Sampling Speed 200ps/sample Single sample: 200/SQRT(12) ~ 58ps But, have Complete Waveform Information Can store 13us at 5GSa/s (before wrapping around)

PD '07 Kobe -- G. Varrner MHz sine wave 6GSa/s Pre-calibration

PD '07 Kobe -- G. Varrner 26 Calibration (1) Linear variation across chip Due to IR drop in feed voltage (can be improved) 6GSa/s 400MHz sine wave Storage Cell Number Extracted Period [ns]

PD '07 Kobe -- G. Varrner 27 Calibration (2) After basic linearity and bin-by-bin correction ~11ps intrinsic (~8ps possible) 6GSa/s 400MHz sine wave Extracted Period [ns] 15ps Linearity only

PD '07 Kobe -- G. Varrner 28 Bench Test timing ~27ps for two edges ~20ps for each edge 6GSa/s ~30ns pulse pair ~40ps for PMT like Signals (working on algorithm)

PD '07 Kobe -- G. Varrner 29 Temperature Dependence 0.2%/degree C (can correct) 6GSa/sSample aperature (172ps = 5.8GSa/s) Matches SPICE simulation

PD '07 Kobe -- G. Varrner 30 Typical single p.e. signal [Burle] Overshoot/ringing Due to Higher bandwidth, “warts” of signal appear

PD '07 Kobe -- G. Varrner 31 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

PD '07 Kobe -- G. Varrner 32 Interleaved Operation LARC ASIC: 64 5 GSa/s = 384GSa/s  Streak camera type applications – ps timing Single shot! uncalibrated room for improvement push BW higher

PD '07 Kobe -- G. Varrner 33 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

PD '07 Kobe -- G. Varrner 34 f-DIRC Array Concept Many k Photodetector channels SiPMs/APDs ASIC Carrier Socket Single Module: (side-view) Tiled Array Readout Board

PD '07 Kobe -- G. Varrner 35 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

PD '07 Kobe -- G. Varrner 36 Backup slide -- cables!

PD '07 Kobe -- G. Varrner 37

PD '07 Kobe -- G. Varrner 38 Blank slide