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)

But must also achieve lowest possible noise to meet ILC resolution goals. How well do we understand Si strip readout 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

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…

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

Measured vs. Expected Noise

Johnson-Noise-Dominated for > 6 strips

“Rigorous Calc”: Carefully measured shape factors Fi, Fv.

Results rather surprising

Re-check methodology Develop P-Spice simulation (as for charge-division studies

Sean’s understudy, Kelsey Collier, will grab the reigns…

Conclusions

SiD sensor: first pass characterization looks fine (complex design!). “Charge Division” sensors shorted by strips.

LSTFE-2 awaits testing (soon!); design refined by studies of LSTFE-1

Charge division approach looks interesting; needs to be optimized and some questions explored (but what happens to S/N and transverse resolution?)

Effects of series noise being questioned; empirical study of readout noise contributions underway

Starting SPICE simulation of “snake” and charge-division setup to calibrate understanding (Ryan Stagg)

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

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.