P

D '0

7 K

obe

--

G. V

arrn

er

1

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

P

D '0

7 K

obe

--

G. V

arrn

er

2

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)

P

D '0

7 K

obe

--

G. V

arrn

er

3

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)

P

D '0

7 K

obe

--

G. V

arrn

er

4

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

P

D '0

7 K

obe

--

G. V

arrn

er

5

LAB3 Architecture Details

• No missing codes• Linearity as good

as can make ramp

• Can bracket

range of interest

P

D '0

7 K

obe

--

G. V

arrn

er

6

LABRADOR sampling & linearity

• Excellent linearity

• Sampling rates up to 4 GSa/s with voltage overdrive

2.6GSa/s

12-bit ADC

P

D '0

7 K

obe

--

G. V

arrn

er

7

Bandwidth Evaluation

TransientImpulse

FFTDifference

Frequency [GHz]

f3dB ~> 1.2GHz

P

D '0

7 K

obe

--

G. V

arrn

er

8

Jiwoo NamUC Irvine

P

D '0

7 K

obe

--

G. V

arrn

er

9

Finer Calibration600MHz Clock

Estimated Limit

P

D '0

7 K

obe

--

G. V

arrn

er

10

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

P

D '0

7 K

obe

--

G. V

arrn

er

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-TOFWithout INL compensation

After INL compensation

+

P

D '0

7 K

obe

--

G. V

arrn

er

12

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)

P

D '0

7 K

obe

--

G. V

arrn

er

13

Precision Timing Motivation (1)

Jerry Va’vra

P

D '0

7 K

obe

--

G. V

arrn

er

14

Motivation (2) --Chromatic Correction

P

D '0

7 K

obe

--

G. V

arrn

er

15

Blank slide

Set-up in End Station A at SLAC, where did ANITA calibration

P

D '0

7 K

obe

--

G. V

arrn

er

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)

P

D '0

7 K

obe

--

G. V

arrn

er

17

UH Prototype Readout Chain

G = 5x105

single p.e. ~1mV

P

D '0

7 K

obe

--

G. V

arrn

er

18

64-channel Amplifier Stackbased on RF amplifiers (cheap, high BW)

Within MCPprofile

Ribbon cable (differential analog) output

P

D '0

7 K

obe

--

G. V

arrn

er

19

Integration Test Results

Raw signal

Scanning Test Set-up:Measured noise ~4mVrmsVoltage Gain ~200High bandwidth

P

D '0

7 K

obe

--

G. V

arrn

er

20

16 BLAB1 ASICs

Processed hit times via CAMAC Full waveforms over USB2

Differential inputs from amp boards

P

D '0

7 K

obe

--

G. V

arrn

er

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

P

D '0

7 K

obe

--

G. V

arrn

er

22

Buffered LABRADOR (BLAB1) ASIC• 10 real bits of dynamic range

Measured Noise

1.4mV

1.8V dynamic range

P

D '0

7 K

obe

--

G. V

arrn

er

23

BLAB1 Analog Bandwidth

• A few fixes (lower power, higher BW)

• Multi-channel BLAB2 -3dB ~300MHz

P

D '0

7 K

obe

--

G. V

arrn

er

24

BLAB1 Sampling Speed

200ps/sample Single sample:200/SQRT(12)~ 58ps

But, haveComplete Waveform Information

Can store 13us at 5GSa/s (before wrapping around)

P

D '0

7 K

obe

--

G. V

arrn

er

25

125MHz sine wave

6GSa/sPre-calibration

P

D '0

7 K

obe

--

G. V

arrn

er

26

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]

P

D '0

7 K

obe

--

G. V

arrn

er

27

Calibration (2)

After basic linearity and bin-by-bin correction~11ps intrinsic (~8ps possible)

6GSa/s

400MHz sine wave

Extracted Period [ns]

15psLinearity only

P

D '0

7 K

obe

--

G. V

arrn

er

28

Bench Test timing

~27ps for two edges~20ps for each edge

6GSa/s

~30ns pulse pair

~40ps for PMT likeSignals (working on algorithm)

P

D '0

7 K

obe

--

G. V

arrn

er

29

Temperature Dependence

0.2%/degree C(can correct)

6GSa/sSample aperature (172ps = 5.8GSa/s)

Matches SPICE simulation

P

D '0

7 K

obe

--

G. V

arrn

er

30

Typical single p.e. signal [Burle]Overshoot/ringing

Due to Higher bandwidth,“warts” of signal appear

P

D '0

7 K

obe

--

G. V

arrn

er

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

P

D '0

7 K

obe

--

G. V

arrn

er

32

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

P

D '0

7 K

obe

--

G. V

arrn

er

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

P

D '0

7 K

obe

--

G. V

arrn

er

34

f-DIRC Array Concept

Many k Photodetector

channels

SiPMs/APDs

ASIC

Carrier Socket

SingleModule:(side-view)

Tiled Array Readout Board

P

D '0

7 K

obe

--

G. V

arrn

er

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

P

D '0

7 K

obe

--

G. V

arrn

er

36

Backup slide -- cables!

P

D '0

7 K

obe

--

G. V

arrn

er

37

P

D '0

7 K

obe

--

G. V

arrn

er

38

Blank slide