ilc instrumentation and simulation r&d at scipp doe site visit thursday, june 18, 2009 bruce...
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ILC Instrumentation and Simulation R&D at SCIPP
DOE Site Visit
Thursday, June 18, 2009
Bruce Schumm
Santa Cruz Institute for Particle Physics
Faculty/Senior
Vitaliy FadeyevAlex Grillo
Bruce Schumm
Collaborator
Rich Partridge(SLAC)
Undergrads
Sean Crosby*Jerome CarmanJared NewmillerSheena SchierKelsey CollierAmy SimonisJeff Schulte*
Chris BetancourtAlex Bogert
The SCIPP/UCSC ILC R&D GROUP
Lead Engineer: Ned Spencer
Technical Staff: Max Wilder
All senior participants mostly working on other projects
*2009 Senior thesis (graduation requirement)
OUTLINE OF SCIPP ILC R&D PROGRAM
LSTFE Frint-End ASIC
• Optimized for ILC (long ladders for barrel; high rates for forward tracking)
• Applicable to both SiD and ILD
SiD KPIX/Double-Metal Development
• SiD baseline; alternative to LSTFE
• SCIPP has done group’s sensor testing, now beginning critical systems tests
Fundamental (“Generic”) R&D
• Use of charge division for longitudinal coordinate (with Rich Partridge)
• Solid-state noise sources
Prospects for RadHard Sensors (far-forward Calorimetry
If funded, will support SLAC collaboration
ESA test beam: SCIPP sensor expertise plus SLAC operation and dosimetry
OUTLINE (Continued)
OUTLINE (Continued)
SiD Simulation Projects
• Tracking and momentum reconstruction validation
• Non-prompt signatures
ILC Tracker Baseline Designs
SiD Baseline: Five barrel and 4 endcap layers, to R = 125cm
ILD Baseline: Si tracking envelops TPC; outer layers
at 1.8m
1-3 s shaping time (LSTFE-I is ~1.2 s); analog measurement is Time-Over-Threshold
Process: TSMC 0.25 m CMOS
The LSTFE ASIC
1/4 mip
1 mip
128 mip
Operating point threshold
Readout threshold
High gain advantageousfor overall performance(channel matching)
FIF
O (L
eadin
g and
trailin
g transition
s)Low Comparator Leading-Edge-Enable Domain
Li
Hi
Hi+4
Hi+1
Hi+2
Hi+3
Hi+5
Hi+6
Li+1
Li+2
Li+3
Li+4
Li+5
Li+6
Proposed LSTFE Back-End Architecture
Clock Period = 400 nsec
EventTime
8:1 Multi-
plexing (clock = 50 ns)
Observed
Expected
1 meter
LSTFE SPACE-POINT RESOLUTION
RMS
Gaussian Fit
Observed noise vs. capacitive load (LSTFE-I)
Simulated space-point resolution for “expected” noise
167 cm Ladder
LSTFE-II PrototypeOptimized for 80cm ladder (ILD barrel application)
Institute “analog memory cells” to improve power-cycling switch-on from 30 msec to 1 msec
Improved environmental isolation
Additional amplification stage to improve S/N, control of shaping time, and channel-to-channel matching
Improved control of return-to-baseline for < 4 mip signals (time-over-threshold resolution)
128 Channels (256 comparators) read out at 3 MHz, multiplexed onto 8 LVDS outputs
Testing underway in SCIPP lab
The SiD KPIX/Double-Metal Baseline Design
10cm2 modules tessellate the five barrel tracking layers
Traces on 2nd (surface) metal layer to two 1024-node bump-bonding arrays
SiD Double-Metal Sensor
• SLAC/FNAL Design
• Hamamatsu Fabrication
• Testing at SCIPP
Sensors bias at ~50 V.Capacitance shown is for all 1840 strips, but strips to backplane only
SiD Tiles: Biasing and Plane-to-Plane Capacitance
For now: single sensor(sensor #26)
SiD Leakage Current (sensor #26): Average leakage for 1840 channels is about ~160 pA/channel
Next Steps:
Larger-scale testing (statistics)
Test of combined KPIX/Double-Metal perforamce to get underway at SCIPP this summer (pending DOE support)
Longitudinal Resolution via Charge Division
Proposed by Rich Partridge, based on seminal paper by Radeka:
V. Radeka "Signal, Noise and Resolution in Position-Sensitive Detectors", IEEE Trans. Nucl. Sci. 21, 51 (1974),
which in turn references earlier work with planar sensors from
R.B. Owen and M.L. Awcock, IEEE Trans. Nucl. Sci. 15, 290 (1968)
Small ($16K) LCRD grant supports this work. Progress due to UCSC undergraduate physics major Jerome Carman
Basic idea: For resistive sensor, impedances dominated by sensor rather than amplifier input impedance; charge should divide proportional to point of deposition. Read out implant (SLAC/FNAL “charge division” sensor has 600 k implant)
Charge Division Sensor Mock-Up
10-stage RC network PC board (Jerome Carman)
Amplifiers:
First Stage: TI OPA657 Low-noise FET OpAmp
Later Stages: Analog Devices ADA4851 rail-to-rail video amp
Measure Noise (either end): 0.64 fC
Charge Division Sensor Mock-Up
Model 600 k resistive implant with 10-stage RC network
Read out at both left (“L”) and right (“R”) ends
Mean Amplifier Response vs. Injection Point
Fairly linear; little offset from 0 appropriate for charge division.
Right-Hand Amplifier
P-Spice, including all parasitics
Observed signal
Longitudinal Resolution Estimate
Trying to measure fractional distance f from right to left end of strip:
Rewrite:
Then,
and dL, dR apparently uncorrelated.
LR
LRf
RLxx
x
RL
RLf /;
1
1
/1
/1
R
R
L
Lxxx
xf
dddwithd
)1(
2d
2
Longitudinal Resolution Estimate: Conclusion
Depends upon location of hit (middle or near end of resistive implant) and the magnitude of the charge deposition.
Assume a 4 fC deposition in the middle of the strip (x=1):
However, note that , so this is not much better.
Optimize shaping time, implant resistivity, ? Goal of better than 0.1 (1cm for SiD sensors).
23.0fC2
fC64.0
2
2dd
2
1d
R
R
L
Lf
29.012
1
Readout Noise for Linear Collider Applications
Use of silicon strip sensors at the ILC tend towards different limits than for hadron collider or astrophysical applications:
Long shaping time
Resistive strips (narrow and/or long), with significant capacitance (for long ladders)
But must also achieve lowest possible noise to meet ILC resolution goals. How well do we understand Si strip readout noise?
Standard Form for Readout Noise (Spieler)
Series Resistance
Amplifier Noise (series)Amplifier Noise (parallel)
Parallel Resistance
Fi and Fv are signal shape parameters that can be determined from average scope traces.
There is some circumstantial evidence that this may be an oversimplification, particularly for the case of series noise…
Strip Noise Idea: “Center Tapping” – half the capacitance, half the resistance?
Result: no significant change in measured noiseHowever, sensors have 237 m pitch Currently characterizing CDF L00 sensors
Measured noise
Expected noise, assuming75% reduction instrip noise
CDF L00 Sensor “Snake”
CDF L00 “Snake”
LSTFE1 chip on Readout Board
CDF L00 Sensor “Snake”
Plus much work eliminating environmental noise, constraining amplifier contributions…Thanks to Sean Crosby, UCSC undergraduate thesis student
“Rigorous Calc”: Carefully measured shape factors Fi, Fv.
Johnson-Noise-Dominated for greater than 6 strips
Results rather surprising Re-check methodology Develop P-Spice simulation (as for charge-division studies)
Sean’s understudy, Kelsey Collier, will grab the reigns…
Radiation-Hard Silicon Sensors (SCIPP/SLAC)
Far-Forward region: Need to tag electrons from two-photon events to remove SUSY backgrounds (to 20 mrad)
Expected doses of 100s MRad anticipated for ILC running (5x limits for probed for ATLAS upgrade studies)
UCSC experience with rad-hard sensors (e.g. Czochralski-process) and characterization, in combination with SLAC testbeams and dosimetry expertise
Funding expected for studies in 2010-2011
Simulation Studies for the SiD Concept
Tracking Performance Evaluation
• Reconstruction Efficiency
• Momentum Resolution
Non-Prompt Tracks
• Reconstruction Algorithms
• GMSB Signatures
Tracking Performance Studies
Efficiency vs. angular distance from jet coree+e- qq at Ecm= 500 GeV
[Jeff Schulte, senior thesis 2009]
“Tri-Plot” Curvature-Error Performance Study
From: Michael Young (UCSC Master’s), Snowmass 2005
Reproduction for current reconstruction by Alex Bogert
3-Hit Tracks & Non-Prompt Signatures
Probably need 5+1 layers for prompt track
If we require 4 hits for non-prompt tracks, sensitive region for kinked tracks is very limited.
e.g.: Position-matching for isolated muons
(mm)
SCIPP algorithm for non-prompt tracks: match 3-hit seeds from tracker with stubs from calorimeter (developed by UCSC undergrads Meyer, Rice)
• Approximately 60% for 3-hit tracks in Z qq events• Being optimized for non-prompt recon-struction (GMSB signature) by undergraduate major Betancourt
0~
Non-Prompt Tracks and GMSB
Concluding RemarksBroad array of generic and specific tracking R&D:
• Optimized Si strip readout (LSTFE)• SiD baseline concept development (KPIX/2Metal)• Generic study of strip noise sources• Radiation hardness• Exploring use of charge division for strip z coord• Sid tracking performance benchmarking• Non-prompt signature from GMSB
Excellent training ground for undergraduate physics/engineering majors (9 currently working on project)
Schumm also ALCPG Tracking group convener, on ALCPG EXEC Committee
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