Progress in the North American
Solid State Tracking R&D program
Rene Bellwied (Wayne State University)
for the North American Solid State groups
International Linear Collider Tracking Review
Amsterdam, March 31st, 2003
Proposed layout for LC tracker
Silicon Drift technology hardware progress & plans
Silicon Strip technology hardware progress & plans
Simulation update
Alignment monitoring project
Summary and Outlook
Silicon detector option for LCD
(small detector, high field B=5T)
Central tracker: Five Layer Device based on Silicon Drift or Silicon Strip Wafers
Radiation length / layer = 0.5 %, sigma_rphi = 7 mm, sigma_rz = 10 mm
Layer Radii Half-lengths
---------------------20.00 cm
26.67 cm
46.25 cm
61.67 cm
72.50 cm
96.67 cm
98.75 cm
131.67 cm
125.00 cm
166.67 cm
56 m2 Silicon, Wafer size: 10 by 10 cm,
# of Wafers: 6000 (incl. spares)
# of Channels: 4,404,480 channels
Project I: Silicon Drift Tracker (SDT)
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Participants: Wayne State University (WSU) & Brookhaven National
Laboratory (BNL)
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BNL Physics: V. Jain, F. Lanni, D. Lissauer
BNL Instrumentation: W. Chen, Z. Li, V. Radeka
WSU: R. Bellwied, D. Cinabro, M. Coscione, V.Rykov (KEK) + new postdoc
Funding: 3-year NSF proposal (pending, positive review): 2003-2005
for a total of $450 K ($ 80, 170, 200 K). Previously we had limited
NSF funding for two years.
Hardware contribution per year (for BNL): $ 25, 50, 90 K
Check out the web at:
http://rhic15.physics.wayne.edu/~bellwied/nlc
SDD’s: 3-d measuring devices
Features:
Low anode capacitance
= low noise
3d information with
1d readout
Pixel-like by storing
2nd dimension in SCA
Low number of RDO
channels based on
charge sharing
in use in STAR (RHIC), in construction for ALICE (LHC)
SVT in STAR
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216 wafers (bi-directional drift)
3 barrels, r = 5, 10, 15 cm,
103,680 channels, 13,271,040 pixels
Resolution: 8 micron and 17 micron
respectively, two-track: 150 micron
Radiation length: 1.4% per layer
 0.3% silicon, 0.5% FEE (Front
End Electronics),
 0.6% cooling and support.
Beryllium support structure.
 FEE placed adjacent to wafers.
No driving capability in very high
resistivity n-type NTD Silicon.
Water cooling.
Typical SDD Resolution
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Bench measurements
now confirmed by STAR
beam time results !
(Feb.03)
Can be improved
through:
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faster drift,
stiffer resistor chain for
voltage gradient,
different anode pitch,
and better starting
material
achieved with one-dimensional readout with 250 mm pitch
Proposed wafer R&D
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Present: 6 by 6 cm active area = max. 3
cm drift, 3 mm (inactive) guard area
Max. HV=1500 V, max. drift time=5 ms
anode pitch = 250 mm, cathode pitch =
150 mm
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Future: 10 by 10 cm active
area (or more ?)
Max. HV=2000 V
Anode pitch, cathode pitch have
to be optimized to give better
position resolution (more
channels = more money)
Stiffer resistor chain dissipates
slightly more heat on detector,
but requires no off detector HV
support and allows a more
linear drift in drift direction
(better position resolution)
Reduce wafer thickness from
280 micron to 150 micron.
Details of mask design
Future: stiffer implanted resistors, no outside power supplies
R.Bellwied, June 30, 2002
Proposed Frontend (FEE) R&D
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Present: bipolar PASA &
CMOS-SCA ( 16 channel per
die, 15 die for 240 channels on
beryllia substrate )
Multiplexing on detector,
8-bit ADC off detector (3m)
Future: 0.25 micron (DSM)
radiation hard CMOS
technology for all three stages
in one single chip (PASA, SCA,
10-bit ADC)
Example: ALICE-PASCAL
Less power consumption and power cycling
allows us to switch from liquid cooling to air
cooling !
Proposed mechanical R&D
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Present: Be angled brackets with
Beryllia hybrids mounted
Future: carbon fiber staves
with TAB electronics wraparounds
Capabilities & Industry contacts
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In house capabilities
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Industry contacts
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High quality clean room facilities for design and prototyping of wafers
and electronics at BNL Instrumentation division
High level CMOS engineering capabilities at BNL Instrumentation
Sensor testing facilities at WSU, Ohio State, and UT Austin
Dedicated electronics testing facilities at BNL Physics
Dedicated mechanical assembly facilities (CMM & CNC devices) at
BNL Physics plus expert machine shop at BNL
Past production contracts with commercial drift detector vendors:
SINTEF, CSEM, EUROSYS, CANBERRA
Potential interests: MICRON, HAMAMATSU
Carbon fiber machining capabilities in house and in US, France & Russia
Potential interest in scientific collaboration in France and Italy (LHCALICE groups)
Hardware deliverables in
present 3 year proposal
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2003 hardware deliverables:
new drift detector wafer layout according to R&D goals.
Feasibility study of BNL stripixel technology vs. drift detectors.
long ladder prototype with old drift wafers (mechanical feasibility)
2004 hardware deliverables:
large batch of prototype detectors, test radiation damage in test beam and with
sources. Beginning design of new frontend electronics
2005 hardware deliverables:
complete design for CMOS DSM type frontend with reduced power consumption
and potentially integrated ADC, test TAB bonding of frontend to detector prototype,
produce large frontend prototype batch. Extensive test beam requirements for
completed detector/FEE combination by end of 2005.
Stripixels:alternative from BNL ?
Alternating Stripixel Detector (ASD)
Interleaved Stripixel Detector (ISD)
Pseudo-3d readout with speed and resolution comparable to double-side
strip detector on single-sided technology (Zheng Li, BNL report, Nov.2000).
Attractive for faster speed and easier to manufacture than double-sided strip
Project II: Long Shaping Time
Si-strip Readout
Participants: Dave Dorfan, Christian Flacco, Alex Grillo, Hartmut
Sadrozinski, Bruce Schumm, Abe Seiden, Ned Spencer, Lan Zhang
(UC Santa Cruz)
Also, a new post-doc (Gavin Nesom) will join the effort in April
Potential external associates: SLAC, LPNHE Paris, CERN RD50
Funding: 2-year, $90,000 grant from the DOE Advanced
Detector R&D Program (funded through 2003, will need to enter
regular LC funding game afterwards)
Present scope of project
Broad scope:
• 9 months graduate student support
• Chip fabrication
• Long-ladder development (existing sensors)
• Electronics servicing to ladder
Detailed ‘deliverables’:
- Characterization of analog characteristics of 0.25 micron structures
- Development of pulse development and electronic simulation for
shaping-time and readout-scheme optimization
- Demonstration of noise level commensurate with readout of 1-2m ladder
- Demonstration of x100 suppression of IR heating loss
- Min-i readout of long ladder
Motivation
Use of long shaping-time read-out (low noise) plus exploitation of
duty cycle permits development of very long, thin ladders with small
power consumption.
Additionally, limited readout and servicing may lead to very limited
material budget in forward region (down to100 mrad)
The limit of the maximum shaping time is given by
consideration of:
- dynamic range in terms of time over threshold (TOT)
- sufficient power cycling time
- shot noise
Present goal: shaping times of 2-5 ms
Anticipated noise levels
Agilent 0.5 mm CMOS process (qualified by GLAST)
Min-i for 300mm Si is about 24,000 electrons
Shaping (ms)
1
1
3
3
10
10
Length (cm)
100
200
100
200
100
200
Noise (e-)
2200
3950
1250
2200
1000
1850
Pulse Development Simulation
Effects incorporated:
• Landau fluctuations (SS_SimSIdE, Jerry Lynch, LBNL)
• Carrier (hole) diffusion / space-charge repulsion
• Lorentz angle, Electronic noise, Pulse digitization / reconstruction
Questions to be answered:
• Signal-to-noise for long ladders, optimal sensor geometry & detector bias
• Evaluation of analog readout scheme (TOT, direct analog, least-bit, etc.;
<7 mm resolution)
• Effect of large magnetic fields, effects of oblique angles of incidence
Example:
Time-Over-Threshold (TOT)
nepulse
r
 ne  min -i
TOT given by difference
between two solutions to
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r
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et
t
TOT/t
nethresh
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 ne  min -i
e t / t
(RC-CR shaper)
Digitize with granularity t/ndig
/r
Result: S/N for 167cm Ladder
Ep = 1-1.5 GeV
At threshold of 0.3*min-I: Eff.:99.9%, noise occupancy:0.1%
(at shaping time of 3ms; 0.5 mm process qualified by GLAST)
Short term / long term plans
Immediately: - begin SPICE-level optimization of shaping
time (assuming 1-2 meter ladder)
- have already begun qualifying GLAST
8-channel `cutoff’ structures for use in 2m ladder
April: begin mechanical design and construction of 2 m ladder
June-July: submission of prototype ASIC
Fall 2003: measure noise and power consumption characteristics
Winter 2003 (likely): begin design of 2nd prototype chip based on
accumulated experience
Winter 2004: begin development of realistic prototype ladder, prepare
for testbeam run
Summer 2004:testbeam studies; begin to develop scheme for back-end
architecture
Simulation update: L vs. SD
Simulation update:
hit occupancy on single wafer
Using STAR detector layout and LC simulations
(t-tbar to 6 jet events at root-s = 500 GeV incl.
g background according to T. Maruyama):
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Around 2000 g/event
leave hit in Silicon,
corresponding to an
occupancy of 13
hits/hybrid
(0.5% occupancy)
51,200 pixels per
hybrid,
20 pixels/hit
Occupancy could be
further reduced by
factor 2 by using
different SCA
Occupancies and tracking
efficiencies with background
For 100% hit efficiency: (97.3±0.10)%
Almost identical to no background !
Project III: Silicon Tracker
Alignment system
Participants: Tim Blass, Sven Nyberg, Keith Riles, Haijun Yang
(University of Michigan)
Involvement: Former graduate student (Jin Yamamoto) & Postdoc
(Haijun Yang) are putting together a benchtop system.
Two undergraduates participate towards senior theses: Tim Blass for
Simulation / fitting software, Sven Nyberg for benchtop
commissioning
Funding: Requested funds in joint UCLC/LCRD proposal (pending),
but have begun purchasing equipment for initial bench setup.
Motivation
Assumption:
Inner detector subject to thermal drifts on time scales too short to
collect adequate control sample of tracks for determining
alignment from data
Conclusion:
Need independent alignment system with rapid tracking of drifts
 “Real time alignment”
Goal:
Carry out R&D toward a low-mass, real-time tracker alignment
system with O(1 micron) precision
Present scope of project
•Focusing efforts on Frequency Scanned Interferometer (FSI)
[A.F.~Fox-Murphy et al., Nuc. Inst. Meth. A383, 229 (1996)]
Basic idea: Measure hundreds of absolute point-to-point distances on
tracker structure, using an interferometer “fanout” of optical fibers from a
central laser. Laser frequency is scanned and fringes counted for each
channel to determine absolute distances. Infer tracker distortions from fit
Work Status: identified equipment needed for benchtop demonstration.
(Laser choice: New Focus Velocity 6308 – on order (~$20K) (tunable
diode laser, ~670 nm, tuning range ~4.5 THz)
Plan to start commissioning: late April (or May) (one postdoc / two
undergraduate students are participating at this point).
Summary & Outlook
Ongoing North American projects:
- central tracker development based on Silicon Drift
- long shaping time readouts for Silicon Strip detectors for
central, forward or intermediate tracker
- alignment monitoring system for Silicon central tracker
Anticipated projects:
- forward tracker, intermediate tracker or TPC envelope based on
Si-strip or scintillating fiber (SiLC coordinates projects between
Europe, Asia, and North America)
Conclusions:
- very promising first ‘wave’ of activity
- alternate technologies are being explored (drift, strip)
- national labs are drawn in (SLAC, BNL)
- R&D funding starts to flow for exploratory 3-year R&D phase
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