1. NPS/CPS/COMCAL - Readout
Hall C Collaboration FJ Barbosa Electronics
NPS/CPS/COMCAL - Readout
F.J. Barbosa, JLab
Chief Electrical Engineer – Hall D
J. Crafts, H. Mkrtchyan, J. Roche, A.Somov, C. Stanislav
PMT & HV Divider
Tests
Readout Infrastructure
Production
Production Tests
Summary
23 January 2018

2. 1. PMT & HV Divider Each Crystal readout area is 20.5 mm square PbWO4
Hall C Collaboration FJ Barbosa Electronics
1. PMT & HV Divider
Crystal
PMT
Each Crystal readout area is 20.5 mm square
PbWO4
# Channels:
NPS/CPS = 1156
COMCAL = 96
Uses Hamamatsu R4125 PMT.
HV Divider
Active
Based on an earlier design by V. Popov
Updated design for reliability, component and production optimization.
New HV Divider (Active)
23 January 2018

3. Typical R4125 PMT Characteristics
Hall C Collaboration FJ Barbosa Electronics
Typical R4125 PMT Characteristics
Diameter 19 mm
Spectral Sensitivity nm – 650 nm (Borosilicate, Bialkali)
Stages stage
Cathode Luminous Sensitivity 115 uA/lm
Anode Luminous Sensitivity 100 A/lm
Dark Current 10 nA
QE %
Rise Time ns
Transit Time 16 ns
T.T.S. (Jitter) FWHM ns
Pulse Height Resolution 7.8 %
Long Term Stability 1 %
Pulse Linearity +/ mA
Gain 1.1 kV kV
23 January 2018

4. Why an Active HV Divider?
Hall C Collaboration FJ Barbosa Electronics
Why an Active HV Divider?
Regulation on the last two dynodes provides for excellent stability and linearity at high rates, large dynamic range.
Operating the PMT at lower gain leads to longer PMT life.
Dynode
Regulation
- Last item in the HV
divider chain
- Zener Regulated
- CB Input
PNP-NPN Driver
Shaper
- ~X10 Gain
2012 IEEE NSS/MIC – V.Popov, H. Mkrtchyan
Preamp is powered from HV supply, eliminating LV supply, connectors, controls, etc.
Higher current from HV supply: 430 uA vs. 170 uA (passive).
HV = -1.1 kV.
PMT Gain = Total Gain = 106
23 January 2018

5. 2. Tests Laser Tests Wavelength 405 nm Pulse Width 70 ps
Hall C Collaboration FJ Barbosa Electronics
2. Tests
Laser Tests
Neutral Density Filter
HV Divider
Wavelength 405 nm
Pulse Width 70 ps
Rate Adjustable
Up to 100 MHz
Intensity Adjustable
Class 3B
PMT R4125
HV Divider Active
HV kV
Cable Length
Short 10 ft
Long 55 ft
Readout
Scope (1 GHz, 5MSPS)
fADC250
Laser
Diffuser
PMT
LED
Neutral density filter allows for amplitude adjustments within the fADC250 range of 500 mV.
Test Variables: Intensity, rate, output drive capability
23 January 2018

6. Readout Pulse Characteristics – Impulse response
Hall C Collaboration FJ Barbosa Electronics
Readout Pulse Characteristics – Impulse response
Amplitude 427 mV
Tr 2.1 ns
Twidth (FWHM) 6.2 ns
Rate 1 kHz
Cable length 10 ft
4 ns
100 mV
Results agree with PMT stated characteristics:
Tr is slightly better due to shaping at the output driver.
Similar performance with long cables (plus dispersion, attenuation, etc.)
23 January 2018

7. Pulse amplitudes = 100 mV to 400 mV Rates = 1 kHz to 5 MHz
Hall C Collaboration FJ Barbosa Electronics
Pulse amplitudes = 100 mV to 400 mV
Rates = 1 kHz to 5 MHz
Linearity is better than 2% up to 2 MHz
A 500 mV pulse corresponds to 1 mA peak anode current --- 1% of PMT spec
Improved linearity, stability, lifetime
23 January 2018

8. Pulse shape behavior with fADC250 was as expected.
Hall C Collaboration FJ Barbosa Electronics
Tests with LED and fADC250
Tests were performed in Hall D with an LED to verify operation with full DAQ.
Pulse shape behavior with fADC250 was as expected.
Linearity was worse: 4% and 1 MHz … at lower amplitudes, likely due to LED near breakdown and slower edges from pulser.
23 January 2018

9. 3. Readout Infrastructure
Hall C Collaboration FJ Barbosa Electronics
3. Readout Infrastructure
Hall C installation details not yet finalized – Patch Panels, Connectors, Cabling
23 January 2018

10. Hall D installation details have been finalized:
Hall C Collaboration FJ Barbosa Electronics
Hall D installation details have been finalized:
COMCAL only has 96 channels, Patch panel with Lemo (signal) and SHV (HV)
23 January 2018

11. 4. Production HV Divider assembly consists of various parts: RG174
Hall C Collaboration FJ Barbosa Electronics
4. Production
HV Divider assembly consists of various parts:
Cable Assemblies
PMT Socket
RG174
Rated for 1.1 kV RMS operation.
Used inside detector chassis, not CL2 rated.
Wire Connections
Connectors
NPS/CPS - TBD
COMCAL - LEMO,SHV
Prototype version shown
PCB Assembly
23 January 2018

12. Hamamatsu socket needs to be machined:
Hall C Collaboration FJ Barbosa Electronics
PMT Socket
Hamamatsu socket needs to be machined:
Metal ring is removed
with hand tools
a bit of an effort needed.
The plastic piece has a lip
Removed by machining
Easy after setup
Required to fit detector PMT assembly housing.
COMCAL have been modified.
NPS/CPS
recommend getting socket without metal ring from Hamamatsu
Removal of lip still required.
PMT Socket (original)
PMT Socket (modified)
23 January 2018

13. PMT Socket attachment to PCB Assembly
Hall C Collaboration FJ Barbosa Electronics
PMT Socket attachment to PCB Assembly
PCB assemblies were procured via contract ( PCBs + component assembly)
PMT Socket (modified)
Wire connections
PCB Assembly
Wiring socket to PCB assembly is labor intensive
Cut wires to length, strip ends, heat shrink insulation, solder
Radially compact assembly, as required by detector PMT housing.
23 January 2018

14. Cable assemblies attachment to PCB Assembly
Hall C Collaboration FJ Barbosa Electronics
Cable assemblies attachment to PCB Assembly
Cable assemblies were procured via contract (cable + connectors, ½ each the # of PMTs)
Bulkhead connectors
PCB and Socket Assembly
Bulkhead connectors secured to detector chassis, patch panel.
Cables attached to PCB Assembly
Two cable assemblies:
LEMO-cable-LEMO and SHV-cable-SHV (COMCAL)
Cables are twice as long as needed
Assembly:
Cut cable assemblies in half, strip ends and solder to PCB
Consider labor needs.
Production version shown
23 January 2018

15. Hall C NPS/CPS – OU, Julie Roche Hall D COMCAL – Jlab, FJ Barbosa
Hall C Collaboration FJ Barbosa Electronics
Production Status
Two initiatives:
Hall C NPS/CPS – OU, Julie Roche
Hall D COMCAL – Jlab, FJ Barbosa
NPS/CPS
HV divider PCBs are in production
Delivery to OU this week
First article tests to follow (Jlab will help)
Remaining steps TBD by Julie (OU) (Jlab will help as needed)
COMCAL
HV divider PCBs have been received (100)
PMT sockets modified (100)
Cable assemblies have been received (100)
Assembly of completed units under way
PMTs received (100)
PMT tests have started
Remaining hardware (fADC250s, crates, HV modules and chassis, cables) has been procured in preparation for installation in Hall D in the Fall of 2018.
23 January 2018

16. Hall C Collaboration FJ Barbosa Electronics
5. Production Tests
Testing plan is still evolving as to which parameters should be measured for:
all PMTs
a few PMTs (From batches? How many?)
HiPot test all HV dividers at -1.1 kV:
no arcs, no trips, supply current < 430 uA
Characterization tests of all PMTs on a single HV divider against a reference known good PMT or comprehensibly :
Gain
Rise time
Linearity QE
Pulse height resolution
Stability
Test all HV dividers with a reference PMT (HV required to test preamp)
Or pair PMTs with HV dividers to form identified units ready for installation:
Tests performance of PMT and HV divider
HV and signal
23 January 2018

17. We developed a portable optical dark box
Hall C Collaboration FJ Barbosa Electronics
Test Setup
We developed a portable optical dark box
12 x 36 x 16 inches
Lid
Latch (2)
Added connectors, both ends
(HV, Signal, LED Pulser)
23 January 2018

18. LED Pulser:Tr, Tf < 2ns,Tw = 5 ns, Fr =1 kHz.
Hall C Collaboration FJ Barbosa Electronics
Inside the box:
Setup:
HV In
Make connections to box: HV, Signal Out to scope or DAQ, LED Pulser In to signal generator.
Settings:
HV = -1.1 kV
LED Pulser:Tr, Tf < 2ns,Tw = 5 ns, Fr =1 kHz.
Signal Out
HV divider
PMT Holder
Test Procedure:
Bracket w/stop
(3D printed)
Attach PMT to HV divider
Insert PMT into PMT holder until PMT contacts stop [for repeatability].
Close lid.
Turn on HV.
Reverse procedure after tests and repeat for next PMTs and/or HV dividers.
Diffuser
Blue LED
Pulser In
Optical Plate (Al, 1/2”)
23 January 2018

19. Hall C Collaboration FJ Barbosa Electronics
6. Summary
Active HV dividers for the Hamamatsu R4125 PMT have been developed, assembled and tested:
Good performance characteristics: linearity, rate, stability, drive
Allows operation of the PMT at lower gain, extending its useful life.
The NPS/CPS detector infrastructure is under development
Choice of connectors, patch panels, etc to be finalized.
HV dividers in production after 1st article acceptance next week.
The COMCAL is scheduled for installation during the Fall of 2018, depending on the availability of Crystals.
HV dividers produced and undergoing final assembly
PMT tests (preliminary): 70 of 70 PMTs passed tests but 2 are marginal.
Final assembly (PMT socket, cables) of the HV dividers is labor intensive. An assembly manual is being prepared.
Production test procedures are being finalized and with consideration to available resources.
Developed a portable optical dark box to ease production testing of PMTs and HV dividers.
We can help the NPS/CPS Jlab/OU effort.
23 January 2018