ILC Tracking R&D at SCIPP

SiD Workshop

Thursday, June 3 2010

Bruce Schumm

Santa Cruz Institute for Particle Physics

Faculty/Senior

Vitaliy FadeyevBruce Schumm

Collaborators

Rich PartridgeTakashi

MaruyamaTom Markiewicz

(SLAC)

Students

Alex Bogert**

Jerome Carman*

London Chappel…Kelsey CollierSpencer KeyDonish KhanOmar Moreno

Jared NewmillerDale Owens

Sheena SchierMatt StantonDustin Stolp*

Aaron TaylorCapella Yee

The SCIPP/UCSC ILC R&D GROUP

Lead Engineer: Ned SpencerTechnical Staff: Max Wilder

Forest Martinez-McKinney

*2010 Senior thesis (graduation requirement) !Carman thesiswins Chancellor’s Award!

** CERN will support summer 2010

OUTLINE OF SCIPP ILC R&D PROGRAM

LSTFE Front-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

SiD Simulation Projects (Not in talk)

• Tracking and momentum reconstruction validation

• Non-prompt signatures

OUTLINE (Continued)

The LSTFE ASIC

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

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)

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 (problems!)

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

LSTFE-II Performance: Time-Over-Threshold vs. Injected Charge

Omar Moreno

Use of KPiX as a Tracking Chip

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

SCIPP attempting to explore whetherMounting KPiX on surface of sensor leads to digital analog feed-through

It has proved difficult to mount KPiX7 onto prototype sensors (passivation between two metal layers fails during bonding)

Forest M.M.: Arranged for bonding with private firm (H&K); then cut shorted traces with laser

Connectivity After Severing Traces

Pad to Pad old R(Ohms) New R(Ohms)---------------------------------------------AVdd to CLK(-) 74.8 3.4MAVdd to CLK(+) 174.2 3.2MAVdd to DVdd 29.6 40KVref to AGND 2.7 101.1Vref to DGND 14.6 102AGND to DGND 16 12.6**DVDD to CLK(-) 75.1 1.4MDVDD to CLK(+) 173.3 1.6M

**This ohmic connection seems to be through the IC and is not fromdamage during bonding.

Next step: build enclosure for assembly and begin to read out (summer)

Triggering on Minimum-Ionizing Particles

Threshold corresponding to the average pulse height for the given injected charge.

10fC injected 9fC injected 8fC injected

4fC injected Mean Threshold:

Example channel 63

Charge in Coulombs

offset

gain

Example Channel 63

0-Charge Input Offset (mV) by Channel(x

10)

Offset in mV for no

input charge

Gain ~4 mV/fC

Next step: Interface with pulse-development simulation to confirm min-I

operability

Charge Division for Silicon Strip Sensors

Final step: practical detectors are not isolated strips. Include two nearest-neighbors in simulation:

Network effects lead to ~5% reduction in longitudinal resolution.

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, particularly for resistive networks?

• How can we minimize noise for resistive networks?

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.

Expected Noise for Custom-Biased L00 Ladder

Spieler formula suggests that series noise should dominate for ladders of greater than 5 or so sensors.

CDF L00 Sensor “Snake”

CDF L00 “Snake”

LSTFE1 chip on Readout Board

Readout Noise ResultsRelative to prior results, have explored “center-tapping” (reading out from center of chain rather than end.

Naïve expectation

Expectation with measuredshape factors Fi, Fv

Measured (end readout)

Measured (center-tap)

Summary of Findings

Reading out from ladder from end:

Significantly less noise observed than expected (network effects ignored in formulation of expectation?)

Reading out from middle (“center tap”):

Noise seems further reduced (~20%) for lengths for which series noise dominates

Will explore with P-SPICE simulation…

AUGUST 2010 MILESTONES Evaluation of channel-to-channel variations in KPIX-9

Exploration of attachment of KPIX-7 to prototype sensor using cutting laser to mitigate shorts from over-glass failure

Initial characterization of LSTFE-II chip

Estimation of longitudinal resolution from resistive charge division measurement of readout noise in the series-resistance limit, including both end- and center-readout

Simulation studies supporting the design of a high-fluence electromagnetic radiation damage study of various silicon sensors

Acquisition and characterization of sensor samples to be used in damage studies

Simulation studies of SiD tracking efficiency performance in forward region

AUGUST 2011 MILESTONES

Characterization of 'analog memory' test structures and assessment of suitability for implementation of power-cycling for LSTFE

Assessment of effects of digital/analog interference effect in KPIX/double-metal assembly

PSpice simulation of series-noise readout limit and comparison with observation

Publication of charge-division results

Test-beam study of radiation damage to various silicon sensor types

Simulation studies of SiD momentum reconstruction performance in forward region

AUGUST 2012 MILESTONES

Re-optimization (for forward region) and fabrication of LSTFE ASIC.

Follow-up testbeam run to confirm radiation hardness of selected Si sensor

Determination of radial extent of sensitivity for reconstruction kinks fro stau decay in the SiD detector

KPiX/double-metal yield and reliability studies

Simulation Studies (ILC Detector Performance)

CURVATURE RECONSTRUCTION PERFORMANCE

1. Compare width of Gaussian fit to residuals with two different estimates:

• Error from square root of appropriate diagonal error matrix element

• Error from Billoir calculation (LCDTRK program)

2. Only tracks with all DOF (5 VTX and 5 CT layers) are considered.

3. Require |cos| < 0.5

Mixture of q/qbar at 500 and 1000 GeV, tau samples at 500 GeV; also use single muons

CURVATURE ERROR vs. CURVATURE

LCDTRK calculation (no beam constraint)

Gaussian fit

SiD02 DetectorModel

Results for Stiff, Central Tracks

In terms of p/p, comparing , with p=100 GeV and |cos| < 0.5 we find

LCDTRK 0.28% 0.28%

Residuals 0.37% 0.39%

LOI Result0.33% ----

Delhi group (Kirti Ranjan et al.) looking into developing Kalman Filter fitter

SiD Forward Tracking EfficiencyStart in central region (|cos| < 0.7); establish Pt cut of 2.0 GeV/c

Capella Yee, Scotts Valley High School

Pt > 2.0 0.7 < Pt < 2.0

Exploring Higher Values of cos

Note: Horizontal axis is -|cos| (learning how to move stat box!)

Capella Yee

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 undergrads Meyer ( U. Chicago), Rice ( UC Irvine)

• Approximately 60% for 3-hit tracks in Z qq events• Being optimized for non-prompt recon-struction (GMSB signature) by undergraduates Stolp and Bogert.

0~

Non-Prompt Tracks and GMSB