1. Latest Results from T979: PSec Time-of-flight
Erik Ramberg
All Experimenters Meeting
September 8, 2008

2. PSEC Test Beam Community
Goal is to develop affordable time of flight measurement for single particles to better than 10 psec
University of Chicago
Camden Eartley
Henry Frisch
Heejong Kim
Jean-Francois Genat
Andrew Kobach
Tyler Natoli
Fukun Tang
Scott Wilbur
Argonne National Laboratory
John Anderson
Karen Byrum
Gary Drake
Ed May
Fermilab
Michael Albrow
Erik Ramberg
Anatoly Ronzhin
SLAC
Jerry Va’vra

3. Technique
Our weapon of choice is the Micro-Channel-Plate PhotoMultiplier Tube (MCP-PMT). We use two in series and measure the time-of-flight difference for 120 GeV proton beam
Cerenkov radiation is crucial for fast timing, so we use quartz radiators coupled to the PMT window (although the PMT window alone can act as the radiator)
To retain timing characteristics, we need multi-anode parallel readout. We are investigating 64 and 1024 isochronos anode boards. All measurements reported here are from a simple passive sum of 4 out of 64 anode pads.

4. Electronic Measurement
MCP/PMT’s
Anode signal
Scintillator Trigger
Constant Fraction
Discriminators (CFD)*
Time to Analog
Convertors (TAC)*
START
STOP
14 bit CAMAC ADC’s *
* = Ortec electronics
NIM signals
10 bit CAMAC ADC’s
Analog
Output

5. Argonne Laser Lab Results: 408nm Results: 635nm
~13 psec at 40 photoelectrons
Results: 635nm
~20 psec at 40 photoelectrons

6. MTest Results from Split Signal from one MCP/PMT
st= 6.4 ps
ADC1 should = ADC2
This is evidence of noise and differential non-linearities
Timing noise level
per channel = 4.6 ps

7. Results from Photonis 25 mm Pore MCP/PMT
st= 21.3 ps
Cut out tails of ADCs
st= 18.6 ps
st(device+noise) = 13.1 ps
Apply small PH slewing correction
st= 19.4 ps
st(per device, excluding noise) = ps

8. Analysis of 10 mm Photonis Tube
Smaller pore size does not automatically achieve better resolution.
We are likely limited by photon generation

9. st(Photek + electronics) = 11 ps
Results for Photek single channel MCP-PMT (10 mm diameter, 5 mm pores)
- Radiator is simply the 5 mm quartz window.
st(Photek + electronics) = 11 ps
st(Photek alone) = 9.6 ps
~ $15K – 20K each!
Better timing resolution from smaller pore size AND large light collection area
Thanks to Photek (UK) for
loan of two PMT210’s !

10. SiPM Results
SiPM = “Silicon PMT”, which is a multi-pixel Geiger mode silicon device for photon counting
SiPM’s used is Hamamatsu 3 x 3 mm2 with 6 x 6 x 16 mm3 poly radiator
Obtained 47ps timing resolution per device, even with poor light collection on one device
3x3 mm2
1x1 mm2

11. Other Projects the Group is Working on:
Investigating large scale production of very small pore MCP at Argonne
Advanced simulation efforts to understand how high speed sampling contributes to resolution
Light generation from cone with half-Cerenkov angle, then paraboloid focus to MCP/PMT. Part of FP420 project
10 psec level timing measurement from FPGA board
‘Bump’ bonding of 1024 anode boards