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TileCal Electronics
A Status ReportJ. Pilcher
17-Sept-1998
17-Sept-98
Outline A status report on the front-end and digitizing
electronics Overview of requirements Development status July ’98 test beam results
Barrel module 0 equipped with 2 superdrawers– 90 channels
First system tests with “in-drawer” digitizers
17-Sept-98
REQUIREMENTS Process 10,000 PMT signals Located in 256 electronics drawers
Up to 45 PMT/drawer Each module self-contained with own electronics
17-Sept-98
REQUIREMENTS
Performance 16 bit dynamic range
Up to 2 TeV in single cell Must see muons
– Calibration and monitoring– Enhance muon ID
Readout resolution should not degrade calorimeter energy resolution
Calorimeter resolution > ~2% Need readout resolution of a few percent in each cell Jet populates many channels
– averaging effects
17-Sept-98
REQUIREMENTS
In situ calibration Gives readout conversion factor (pC/count) Measures linearity Calibrates source integrator
Slow integrator for PMT current
LVL1 trigger tower sums
17-Sept-98
ORGANIZATION 3-in-1 Card
One per PMT Plugs into PMT anode
Near-ideal current source Pulse shaped signals to
digitizers Integrator for source calibration
and monitoring min-bias current
Gain switching Output gating
Charge injection for electronics calibration
LVL1 Trigger output Gated
17-Sept-98
ORGANIZATION Mother Boards
set of 4 in tandem per drawer
Services and control signals to 3-in-1
Digitizer Boards set of 4 (or 8) per drawer
Connections to drawer TTC fiber S-LINK fiber D.C. Power CANbus
17-Sept-98
Bigain pulse shaper 7-pole Bessel filter (purely passive)
Exploit current source nature of PMT No noise, no power Very linear
Clamping amplifiers and drivers Gain ratio 64:1 for dual 10-bit ADCs
3-in-1 Card Status
17-Sept-98
Output pulse to digitizers Low Gain (1 GeV/mV)
Full scale signal
High Gain (16 MeV/mV) Muon signal
3-in-1 Card Status
Low Gain Output1000 GeV input(full scale)
-0.2
0
0.2
0.4
0.6
0.8
1
-100 -50 0 50 100 150 200 250 300 350 400
Time (ns)
High Gain Output200 MeV input(muon signal)
-0.005
0
0.005
0.01
0.015
0.02
0.025
-100 -50 0 50 100 150 200 250 300 350 400Time (ns)
17-Sept-98
Linearity and calibration Residuals < 1 count over full dynamic range
3-in-1 Card Status
±1 count
±1 count
17-Sept-98
Source integrator Essential for Cs calibration and monitoring of
calorimeter See preceding talk
Cs calibration has short-term reproducibility of ~ 0.1%
Should be matched by electronics stability
3-in-1 Card Status
17-Sept-98
independent readout for each drawer ADC board + CANbus
Multiplexed to individual 3-in-1 cards
Integrator Readout Status
17-Sept-98
Source Integrator Stability better than 0.1% over 2 months (calibrator
+ integrator)Integrator Stability (Drawer A)
-2.0
-1.0
0.0
1.0
2.0
0 10 20 30 40 50 60 70 80
Time (days)
Gain 1Gain 2Gain 3Gain 4Gain 5Gain 6
Integrator Stability (Drawer B)
-2.0
-1.0
0.0
1.0
2.0
0 10 20 30 40 50 60 70 80
Time (days)
Gain 1Gain 2Gain 3Gain 4Gain 5Gain 6
17-Sept-98
Digitizer Status Partially equipped Barrel Module 0 (30
channels) in July ’98 First system test of “in-drawer” digitizers
Two 10-bit 40 MSPS ADCs per channel High gain scale 0 - 16 GeV (16 MeV/count) Low gain scale 0 - 1000 GeV (1 GeV/count) Commercial components
TTC input on optical fiber 40 MHz clock, LVL1 accept, digitizer control data
17-Sept-98
Digitizer Status Pipeline delay via custom ASIC
Digital memory unit (DMU) Originally developed for PHENIX TEC
Output via optical S-LINK Read with optical LDC/PMC, RIO processor
17-Sept-98
July ’98 Test Beam Results Laser calibration
Measure linearity and stability of PMT and electronics
3 PIN diodes to monitor laser
17-Sept-98
July ’98 Test Beam Results Digitized signals
More pedestal noise on high gain channel Digitizing clock not synchronized to beam
17-Sept-98
July ’98 Test Beam Results Pedestal Noise
High Freq. Noise
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
0 5 10 15 20 25 30Digitizer Number
High GainLow Gain
Low Frequency Noise
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
0 5 10 15 20 25 30
Digitizer Number
High Gain
Low Gain
Noise for high gain branch ~ 1.1 counts Corresponds to ~ 0.4 photoelectrons in PMT (17 MeV) SPICE simulation predicts 1.2 counts
Noise for low gain branch ~0.5 counts SPICE simulation of 3-in-1 card predicts 0.3 counts Digital noise < ~ 0.4 counts
17-Sept-98
July ’98 Test Beam Results Muon response for the 3 sampling depths (=90)
Pedestal superimposed Using “signal” from empty events Width reflects energy algorithm as well as electronics
– 10 digitizations used for each measurement (not optimized)
Muon signal well resolved from pedestal
17-Sept-98
July ’98 Test Beam Results Electron response
Most energy in a single cell Channel-to-channel intercalibration less important
Calibration not yet available 50 GeV and 100 GeV electrons
17-Sept-98
July ’98 Test Beam Results
Use e- response to measure readout resolution
δE
E=
23%
E⊕ 0.5%⊕
a
E
Fit for a reflects readout resolution and energy algorithm
e - Energy Resolution
0
2
4
6
8
10
10 60 110 160 210 260
Energy (GeV)
'98 Measurements'97 MeasurementReadoutSamplingConstant TermTotal
17-Sept-98
Energy resolution gives readout resolution of 0.5 counts/sample
ADC quantization error noise ...
Noise study gave 0.5 counts
Well understood result Readout will not limit
resolution of hadronic calorimeter
July ’98 Test Beam Results
17-Sept-98
July ’98 Test Beam Results
Pion energy resolution from test beam Under analysis Needs cell-to-cell intercalibration
Electron shower largely contained in single cell
17-Sept-98
Future Planning Radiation hardness tests this fall Design review this fall Electronics PRR spring ’99 3-in-1 production to start spring ’99 Version 2 of digitizer to be demonstrated
spring ’99 Final electronics needed for module
calibration in ’00, ’01, ’02 Finish production of electronics in ’02
Before start of installation
17-Sept-98
Conclusions TileCal electronics shows good performance
Achieved required dynamic range with linear system
Very low system noise Electron energy resolution used to measure
readout resolution First successful tests of “in-drawer” digitizers
No unexpected problems so far Still a lot of work to do!
Expect to start production on schedule