1. Update of time measurement results with the USB WaveCatcher board & Electronics for the DIRC-like TOF prototype at SLAC D.Breton , L.Burmistov, J.Maalmi (LAL Orsay)

2. Introduction The goal for the Forward TOF electronics is:
To measure the arrival time of a fast pulse for particle identification with an electronic precision better than 10 ps at high scale, low power and low cost
Expected total time resolution : ~90 ps /√Npe-
Required < 30 ps
Proposed solution is based on Analog Memories and digital treatment of the digitized signal!

3. The WaveCatcher board
The principle is to build a TDC working directly on analog pulses !
Pulsers for reflectometry applications
Reference clock: 200MHz => 3.2GS/s
Board has to be USB powered
=> power consumption < 2.5W
1.5 GHz BW
amplifier.
µ USB
2 analog
inputs. DC
Coupled.
Trigger
input
Trigger
output
+5V
Jack
plug
Trigger fast
discriminators
SAM Chip
Dual 12-bit ADC
Cyclone FPGA

4. Acquisition software with graphical user interface
This software can be downloaded on the LAL web site at the following URL:

5. Lab results for time distance
Source: asynchronous pulse sent to the two channels with cables of different lengths.
Time difference between the two pulses extracted by CFD method.
Threshold determined after linear interpolation of the splined neighboring points.
Spline and normalization
Threshold interpolation
9.64ps rms
Ratio to peak
0.23
Time
0.23
σΔt ~ 10ps rms
jitter for each pulse ~ 10/√2 ~ 7 ps !
Other method used: Chi2 algorithm based on reference pulses.

6. Conditions : 40pe- and low gain (2-3 104)
SLAC laser test
10µm MCP-PMTs:
Conditions : 40pe- and low gain ( )
WaveCatcher Board
100Hz
Digital CFD method
TARGET board

7. SLAC test summary
Sampling
period!
From this we could conclude that applying a very simple algorithm, which is very simple to integrate in a FPGA  (finding a maximum & linear interpolation between two samples, i.e., without a use of the Spline fit) already gives very good results (only 10% higher than the best possible resolution limit).
Summary of
all the test results

8. Last conclusions at Annecy
The USB Wave Catcher has become a nice demonstrator for the use of matrix analog memories in the field of picosecond time measurement
Different methods have been studied to analyze data taken with MCP-PMTs :
CFD and Chi2 algorithm give almost the same time resolution :
Double pulse resolution : ~ 24 ps => Single pulse resolution: ~ 17 ps
Even the simplest CFD algorithm can give a good timing resolution
Single pulse resolution : ~ 18 ps
it can be easily implemented inside an FPGA (our next step)
=> reduces the data rate => can be used for very large scale detectors

9. NIM paper has been submitted in April
Abstract: … There is a considerable interest to develop new time-of-flight detectors using, for example, micro-channel-plate photodetectors (MCP-PMTs). The question we pose in this paper is if new waveform digitizer ASICs, such as the WaveCatcher and TARGET, operating with a sampling rate of 2-3 GSa/s can compete with 1GHz BW CFD/TDC/ADC electronics ... …
Conclusion: … The fact that we found waveform digitizing electronics capable of measuring timing resolutions similar to that of the best commercially-available Ortec CDF/TAC/ADC electronics is, we believe, a very significant result. It will help to advance the TOF technique in future.

10. Window for time measurements

11. Chi2 results with the WaveCatcher Software
Spline Interpolation with 3.12 ps /bin +
Chi2 algorithm on the Leading Edge of the pulses (10 to 30%)

12. CFD results with the WaveCatcher Software
Simple Digital CFD : as should be implemented in an FPGA ! Peak detection + Linear interpolation of threshold

13. Time Measurements with SiPMs
SiPMs 1 et 9 mm² HAMAMATSU, FBK, Photonique, Sensl
SiPM
laser

14. Setup Adjustment of the number of PhotoElectrons
1st plot: with multiple pe-
2nd plot with adjustment to
~1 pe- like expected for TOF
Charge Histograms
Photoélectrons number
SiPM 1 2
laser

15. Preliminary results for time measurement with SiPMs
SiPM 10-50S BK4s (pixel : 50 µm)
70,55 V – 20 °C +/- 0,1 °C
SiPM S BK4s (pixel : 100 µm)
71,5 V – 20 °C +/- 0,1 °C
Time (ns)
σ= 75,5 ps (gaussian fit)
RMS= 170 ps
PRELIMINARY
Time (ns)
σ= 54,6 ps (gaussian fit)
RMS = 140 ps

16. Preliminary results for time measurement with MCP-PMTs
MCP-PMT Burle X8512
We started studying the 25µm MCP-PMTs
First runs with many photons gave:
~14 ps (rms)
Then with less (?) photons: ~23 ps (rms)
Still working towards the single pe-

17. Electronics for the DIRC-like TOF prototype at SLAC CRT D. Breton & J
Electronics for the DIRC-like TOF prototype at SLAC CRT D.Breton & J.Maalmi (LAL Orsay)

18. Experiment setup

19. Main requirements for the Electronics
For the two-bar test at SLAC, we have to build a synchronous sixteen channel acquisition system:
The latter has to work with a common clock
There we take benefit of the new external clock input of the WaveCatcher V5
It will be self-triggered but it will also be synchronized with the rest of the CRT:
Event readout
Event time tagging
USB has to be ran at a distance of 40m
=> it will be based on a dedicated commercial set of two boards, interconnected by an Ethernet cable

20. Base PCB & cable All the lines between the MCP anodes
and the cable inputs are 14.7mm long

21. The USB_WaveCatcher board V5
USB interface
=> 480Mbits/s
Pulsers for reflectometry applications
Reference clock: 200MHz => 3.2GS/s
Board has to be USB powered
=> power consumption < 2.5W
1.5 GHz BW
amplifier.
µ USB
Trigger
input
2 analog
inputs. DC
Coupled.
Clock input
Trigger
output
+5V
Jack
plug
Trigger fast
discriminators
SAM Chip
Dual 12-bit ADC
Cyclone FPGA

22. Acquisition software with graphical user interface
A new version dedicated to the 16-channel acquisition is under development.

23. Clock and control board
Electronics setup
To / from
trigger
USB
Repeater
USB hub 8
16 channels
MCP-PMT
36dB
Amp
Trig out
CH0
CH1
Clk in
Trig in
Trig out
CH0
CH1
Clk in
Trig in
Trig out
CH0
CH1
Clk in
Trig in
Trig out
CH0
CH1
Clk in
Trig in
Trig out
CH0
CH1
Clk in
Trig in
Trig out
CH0
CH1
Clk in
Trig in
Trig out
CH0
CH1
Clk in
Trig in
Trig out
CH0
CH1
Clk in
Trig in
USB
36dB
Amp
Ext trig out
Ext trig in
USB
USB
USB
USB
USB
USB
USB
USB
Clk out 8
Trig out 8
Trig in 8
36dB
Amp
36dB
Amp
8 USB WaveCatcher V5
Clock and control board
USB
Repeater
DAQ PC

24. MITEQ amplifier Model: AM-1610-1000 Input and output connector: SMA
Frequency Minimum 1 MHz
Frequency Max MHz
Electrical Specifications
Gain Minimum 36 dB
Gain Flatness dB+/-
Noise Figure 3.3 dB
Voltage 1 (Nominal) 15 V
Current 1 (Nominal) 160 mA
Impedance 50 Ohms
Price:
Per / Euros
Per / Euros

25. Crate for WaveCatcher boards
Recycled 6U crate
Naked WaveCatchers
mounted on 3U carrier boards
All the cables inside the crate except the signal inputs which will be located on the front panel side

26. Clock and control board
From WaveCatchers
To WaveCatchers
From CRT
To CRT

27. Comments about electronics
Baseline is to use sixteen individual 36 dB amplifiers but a solution with two boards each housing 8 amplifiers with programmable gain is under study
It could be used for the second step based on the SL10 MCPs
It is necesssary to test it in view of the final design
Special care will be taken in the clock distribution in order to maintain the individual time performances of the WaveCatcher boards
Common trigger for the WaveCatcher boards will be the OR of their individual triggers on signal
This will stop the signal recording into the analog memory but readout could be validated by a second signal coming from the CRT
Upon each event, the acquisition software will fetch the time in the CRT µPC => synchronization of events with the CRT’s

28. Targetting the final design
Final design will permit readout of ~ 672 channels.
We need hit charge and time
Pulse width ~ 5ns => 15 samples (3,2GS/s) per hit read at ~ 20 MHz => total memory readout time of 750 ns per hit
Mean hit rate of 470 kHz (~2 µs)
Analog memory will have to avoid creating dead-time => integrated derandomizer?
Block diagram of one channel
MCPPMT
Level1 trigger
Amplifier
Auto-triggered
analog memory
2-5 GS/s
ADC
CFD +
latency buffer
(PRO ASIC 3
Actel FPGA)
Control
To DAQ

29. Conclusions We are still working on the WaveCatcher software
We integrated a lot of functionnalities for time measurement
The first results with SiPM tend to show that SiPM are not adapted for high precision time measurements
We just started working with MCPPMT
We should get our first results with MCPPMT and single pe- very soon
Electronics for the DIRC-like TOF prototype is well on tracks
It includes hardware and software