TileCal Electronics
A Status Report
J. Pilcher
17-Sept-1998
Outline

A status report on the front-end and digitizing
electronics
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Overview of requirements
Development status
July ’98 test beam results

Barrel module 0 equipped with 2 superdrawers
– 90 channels

17-Sept-98
First system tests with “in-drawer” digitizers
REQUIREMENTS
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
Process 10,000 PMT signals
Located in 256 electronics drawers
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Up to 45 PMT/drawer
Each module self-contained with own electronics
17-Sept-98
REQUIREMENTS

Performance
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16 bit dynamic range
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Up to 2 TeV in single cell
Must see muons
– Calibration and monitoring
– Enhance muon ID

Readout resolution should not degrade
calorimeter energy resolution
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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
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Gives readout conversion factor (pC/count)
Measures linearity
Calibrates source integrator
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
Slow integrator for PMT current
LVL1 trigger tower sums
17-Sept-98
ORGANIZATION
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3-in-1 Card
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One per PMT
Plugs into PMT anode

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Pulse shaped signals to
digitizers
Integrator for source calibration
and monitoring min-bias current
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
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Near-ideal current source
Gain switching
Output gating
Charge injection for electronics
calibration
LVL1 Trigger output
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17-Sept-98
Gated
ORGANIZATION
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Mother Boards
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Digitizer Boards
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set of 4 in tandem per
drawer
Services and control signals
to 3-in-1
set of 4 (or 8) per drawer
Connections to drawer
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TTC fiber
S-LINK fiber
D.C. Power
CANbus
17-Sept-98
3-in-1 Card Status
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Bigain pulse shaper
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7-pole Bessel filter (purely passive)
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Exploit current source nature of PMT
No noise, no power
Very linear
Clamping amplifiers and drivers
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17-Sept-98
Gain ratio 64:1 for dual 10-bit ADCs
3-in-1 Card Status
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Output pulse to digitizers
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Low Gain (1 GeV/mV)
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Full scale signal
High Gain (16 MeV/mV)
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17-Sept-98
Muon signal
3-in-1 Card Status
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Linearity and calibration
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Residuals < 1 count over full dynamic range
±1 count
±1 count
17-Sept-98
3-in-1 Card Status

Source integrator

Essential for Cs calibration and monitoring of
calorimeter


See preceding talk
Cs calibration has short-term reproducibility of ~
0.1%

17-Sept-98
Should be matched by electronics stability
Integrator Readout Status
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independent readout for each drawer
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ADC board + CANbus
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17-Sept-98
Multiplexed to individual 3-in-1 cards
Source Integrator

Stability better than 0.1% over 2 months (calibrator
+ integrator)
17-Sept-98
Digitizer Status
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Partially equipped Barrel Module 0 (30
channels) in July ’98
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Two 10-bit 40 MSPS ADCs per channel
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First system test of “in-drawer” digitizers
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
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40 MHz clock, LVL1 accept, digitizer control data
17-Sept-98
Digitizer Status
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Pipeline delay via custom ASIC
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Digital memory unit (DMU)
Originally developed for PHENIX TEC
Output via optical S-LINK
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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
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17-Sept-98
3 PIN diodes to monitor laser
July ’98 Test Beam Results
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Digitized signals
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More pedestal noise on high gain channel
Digitizing clock not synchronized to beam
17-Sept-98
July ’98 Test Beam Results
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Pedestal Noise
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Noise for high gain branch ~ 1.1 counts
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Corresponds to ~ 0.4 photoelectrons in PMT (17 MeV)
SPICE simulation predicts 1.2 counts
Noise for low gain branch ~0.5 counts
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17-Sept-98
SPICE simulation of 3-in-1 card predicts 0.3 counts
Digital noise < ~ 0.4 counts
July ’98 Test Beam Results

Muon response for the 3 sampling depths (=90)
 Pedestal superimposed
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Using “signal” from empty events
Width reflects energy algorithm as well as electronics
– 10 digitizations used for each measurement (not optimized)
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Muon signal well resolved from pedestal
17-Sept-98
July ’98 Test Beam Results
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Electron response
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Most energy in a single cell
Channel-to-channel intercalibration less important

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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

E
23%
a

 0.5% 
E
E
E

Fit for a
reflects readout
resolution and
energy algorithm

17-Sept-98
July ’98 Test Beam Results

Energy resolution gives
readout resolution of
0.5 counts/sample
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ADC quantization error 
noise  ...
Noise study gave 0.5
counts
Well understood result
Readout will not limit
resolution of hadronic
calorimeter
17-Sept-98
July ’98 Test Beam Results

Pion energy resolution from test beam
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Under analysis
Needs cell-to-cell intercalibration

17-Sept-98
Electron shower largely contained in single cell
Future Planning
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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

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Electron energy resolution used to measure
readout resolution
First successful tests of “in-drawer” digitizers
No unexpected problems so far
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Very low system noise
Still a lot of work to do!
Expect to start production on schedule
17-Sept-98