Update on Electronics Activities Jim Pilcher University of Chicago 20-Jan-2006.
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Transcript of Update on Electronics Activities Jim Pilcher University of Chicago 20-Jan-2006.
Update on ElectronicsActivities
Jim PilcherUniversity of Chicago
20-Jan-2006
January 20, 2006 J. Pilcher2
Readout Electronics
Last talk on electronics was some time ago
Need update on recent activities at Chicago PMT testing R&D on readout Prototype tank being prepared
Recall electronics parameter list on web site http://hep.uchicago.edu/~pilcher/th13/electronics/electronics.html
Active Excel file which will update if input assumptions are changed
Also earlier electronics talk on web site
January 20, 2006 J. Pilcher3
PMT Testing The prototype tank being prepared will use six 8-inch PMTs
More details on tank later in the talk We have 2 from each of three vendors
Candidate tubes for final detector Hamamatsu R5912
– 10 stages, G=107 @ 1500V, dark count rate 4.0 KHz
Photonis XP1806– 11 stages, G=107 @ 1340V, dark count rate 1.6 KHz
Electron Tubes 9354KFLB– 12 stages, G=107 @ 1300V, dark count rate 4.0 KHz
All have low activity glass envelope All equipped with manufacturers’ bases
January 20, 2006 J. Pilcher4
PMT Testing Testing to date is limited
Have looked mainly at single pe pulse shapes
Impacts readout electronics Have looked with illumination of full photocathode and of a 2 cm x 2 cm region
Have operated at HV for G = 107
Measurements also underway in low background lab on activity of glass
Will be reported at future meeting Test with small beaker (~ 200 ml) of liquid scintillator and Co-60 source in a dark box
January 20, 2006 J. Pilcher5
PMT Testing Single pe pulse
from Hamamatsu shows reflection ~10 ns after primary peak
Not scope connection
Multiple pe signal includes scintillator properties
Hamamatsu R5912 - single pe
-120
-100
-80
-60
-40
-20
0
20
-15 -10 -5 0 5 10 15 20 25 30 35 40 45 50
Time (ns)
Voltage (mV)
FWHM = 5.0 ns
t_rise = 3.4 ns
t_fall = 3.7 ns
Hamamatsu R5912 - multiple pe
-600
-500
-400
-300
-200
-100
0
100
-15 -10 -5 0 5 10 15 20 25 30 35 40 45 50
Time (ns)
Voltage (mV)
FWHM = 12.8 ns
t_rise = 5.2 ns
t_fall = 15.0 ns
January 20, 2006 J. Pilcher6
PMT Testing Photonis tube
showed low gain and broad signal
Perhaps faulty Need to test
second tube
Electron Tubes tube is similar to Hamamatsu but slightly slower
Photonis XP1806 - all pulses
-250
-200
-150
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-50
0
50
-15 -10 -5 0 5 10 15 20 25 30 35 40 45 50
Time (ns)
Voltage (mV)
FWHM = 13.7 ns t_rise = 10.8 ns t_fall = 21.1 ns
Electron Tubes 9354KFLB - single pe
-160
-140
-120
-100
-80
-60
-40
-20
0
20
-15 -10 -5 0 5 10 15 20 25 30 35 40 45 50
Time (ns)
Voltage (mV)
FWHM = 6.0 nst_rise = 5.7 nst_fall = 13.8 ns
January 20, 2006 J. Pilcher7
PMT Testing Much more work to be done on PMTs
Suggestions and/or visitors welcome No special hardware on hand for detailed measurements
Photocathode uniformity, linearity, quantum efficiency, gain, after-pulsing, magnetic field sensitivity, etc.
Our goal was to take a first look before using them in prototype tank
We would be happy to have help from others on PMTs
January 20, 2006 J. Pilcher8
Readout R&D Strawman proposal presented in earlier talk on web site Dual range, 12-bit readout on each PMT
Gain ratio 32:1 between two scales Separate ADCs on each scale for easy inter-calibration of scales
Overall dynamic range 17 bits 15 counts/pe at low end of range High end ~70 times most probable single muon signal for “average” PMT
PMTs close to muon will receive much larger signals
High energy radiative tail for muons Multiple muons from cosmics Suitability to be confirmed by Monte Carlo studies
January 20, 2006 J. Pilcher9
Readout R&D Design features of strawman approach
Similar to readout approach in ATL AS Tile Calorimeter, Auger, Quiet, …
Convert PMT signal to a pulse of standard shape but amplitude proportional to input charge
Create Gaussian shape with FWHM of 30 ns Sample with commercial 12-bit ADCs every 15 ns. Extract amplitude and time of signal with respect to sampling clock by digital signal processing
Can give sub-1% amplitude resolution and ns time resolution (seen in ATLAS)
Shaper and pre-amp on PMT base Digitizer in VME crate outside containment sphere
January 20, 2006 J. Pilcher10
Readout R&D Shaping obtained with purely passive components (LC) Exploits current source nature of PMT Linearity guaranteed Very low noise Insensitive to input shape Follow with active preamp and line driver
PMTPreampand
Line Driver
January 20, 2006 J. Pilcher11
Readout R&D Packaging and system planning
Shaper on PMT Perhaps on same PCB as voltage divider
Two shielded twisted pair outputs Digitizer on VME board
32 channels per board Form local trigger information from patch of 32 PMTs– Total number of pe
Overall trigger could be based on trigger info from 32 patches
Would allow some geometrical requirements as well as total signal
Trigger could be based on same data as read out
January 20, 2006 J. Pilcher12
Readout R&D Digitize waveform from PMT/shaper every 15 ns
DSP processing extracts amplitude and time Shape below is SPICE simulation of shaper
January 20, 2006 J. Pilcher13
Readout R&D Possible organization
VME Modules
January 20, 2006 J. Pilcher14
Readout R&D Status
Working on shaper design Thinking about VME board
How do we prove this will do the job? Prototype tank already being prepared
Record data with calibration sources Use proposed shaper but commercial digitizer
A CAEN VME module can sample every 0.5 ns Can sample PMT directly to show ultimate time resolution
Can sample shaped signal every 15 ns to show time resolution and performance of shaped scheme
January 20, 2006 J. Pilcher15
Readout Electronics CAEN V1729 VME digitizer for prototype tests• Bandwidth 300 MHz
• Up to 2 GHz sampling rate into storage caps.
• 12 bit A-to-D conversion after trigger
• Memory with 2520 samples per channel
A trigger stops the continuous sampling
• 4 differential inputs per module (2 PMTs)
• 16-bit dynamic range using high-gain and low-gain inputs from each PMT
11 bits reading PMT directly• $2.2K / channel (very pricey!)• 3 modules on order
January 20, 2006 J. Pilcher16
Readout R&D How might electronics design evolve? We have a strawman proposal for front-end and organization
Other options should be considered too Cost and performance important metrics
Alternative readout schemes could be tried with prototype tank
Visitors welcome Many important electronics topics need work
Trigger, signal processing, LV system, HV system, DAQ system
January 20, 2006 J. Pilcher17
Prototype tank Geometry?
~ 1.6 m3 normal liquid scint.
~ 4.4 ℓ Gd loaded scint. In acrylic sphere Movable along axis of cylinder
3 PMTs on each end
January 20, 2006 J. Pilcher18
Prototype tank Plan is to run with various sources and cosmic muons
Californium– a fission source giving prompt gammas plus delayed gammas
from neutrons capture in Gd
Co-60 for photons Validate Monte Carlo code
Tank has different geometry but most of the physics processes of the full detector
Validate readout electronics Get experience with candidate PMTs Test bed for candidate readout systems
Status Tank being fabricated and expected in early February
Three CAEN V1729 modules on order A senior thesis project for Abby so data is needed by May
January 20, 2006 J. Pilcher19
Conclusions That’s it from Chicago!