1. The New Readout Electronics for the SLAC Focusing DIRC Prototype (SLAC experiment T-492 )
L. L. Ruckman, G. S. Varner
Instrumentation Development Laboratory (ID-Lab)
University of Hawaii at Manoa, Department of Physics
November 01, 2007

2. BaBar DIRC DIRC (Detection of Internally Reflected Čerenkov)
~11,000 PMT
Very large SOB (Stand Off Box)

3. focusing DIRC
fDIRC (focusing Detection of Internally Reflected Čerenkov)
Smaller SOB and requires higher density photodector array
Possible use in Super B KEK, Japan

4. SLAC fDIRC Prototype
Six days of 10 GeV electron beam in End Station A at SLAC
Recorded 10M triggers, 800k good single-track events
PAMDA TOF, reference Joe

5. fDIRC Photodector Array
7 MCP Slots (microchannel plate)
64 photo channels in each MCP
Testing both Burle and Hamamatsu MCP technology
UH readout MCP
PAMDA TOF, reference Joe

6. MCP Readout Setup Low cost, High gain RF AMPS G = 5x105
single p.e. ~1mV

7. Circuit Board Readout Features
Differential Analog Input
CAMAC
16 Waveform Sampling Channels
USB2.0

8. Buffered Large Analog Bandwidth (BLAB1)
Measured ASIC Noise
Custom Waveform Sampler
65 k deep sampling
High speed sampling
Low power consumption
10 real bits of dynamic range
BLAB1 ASIC is presented by
G. Varner: IEEE NSS 2007 N29-1
1.45 mV
1.65 V dynamic range
MHz
Point to the talk and show this and ADC characteristics
BLAB1
“An Oscilloscope on a chip”

9. Measured Burle Cross-talk
With higher bandwidth, ringing nature well seen
Laser scan with light focused at MCP center
16 channel readout shown from Hawaii’s readout system

10. Digitizing Characteristics
~10mV RMS
Low noise with RF AMPs powered on
Stable Sampling speed
(5.78 GSa/s)
Useful Linux Software GUI
173+/- 1.4 ps/sample

11. High Timing Resolution
Split of a 50 ohm pulse to create an ADC sampling trigger and analog pulse
By curve fitting to the waveform data, able to get high timing resolution of the time position for the pulse’s peak
Test signal
Sigma ~ 38 ps

12. LP Filtering & Curve Fitting
Remove out of band noise with a low pass FFT software filter
Curve fit to find the time of the peak

13. Timing Distribution
Position 1
good single e- track events have not been filtered out from the Hawaii dataset, yet
Distribution widths correlated to number of internal reflections
Direct Photons
Indirect Mirror Reflected Photons
Position 5

14. Summary and Progress
Prototype of a high speed photodetector waveform sampler SLAC
High timing resolution algorithm for pulse fitting developed
10 million triggered events with 800k good single e- track events collected
Over a terabyte of raw ADC data collected for Hawaii’s electronics

15. Acknowledgement
Special thanks to Jerry Va’vra and Joe Schwiening at SLAC
This work has been supported by the Department of Energy Advanced Detector Research Program Award

16. End of Slides

17. Spare Slide
Diagram from J. Va’vra – Talk at Fermilab March 2007

18. Spare Slide (LAB Technology)
Variant of the LABRADOR 3
3mm x 2.8mm, TSMC 0.25um
64k samples deep
Multi-MSa/s to Multi-GSa/s
12-64us to form Global trigger
Successfully flew on ANITA in Dec 2006 /Jan 2007 (<= 50ps timing)

21. -40 mV Cutoff
Discarded events
Skimmed Events