RD Towards a Linear Collider Detector DOE Site

R&D Towards a Linear Collider Detector DOE Site Visit Wednesday July 27, 2011 Senior: Fadeyev, Schumm, Spencer Students: Bogert, Carman**, Chappelletvolpini*, Cunnington, Gomez, Key, Khan*, Maduzia, Mallory, Mc. Fadden, Michlin, Mistry, Moreno, Newmiller, Ramirez, Schier**, Taylor*, Thompson* Senior thesis completed ** Campus award for senior thesis *

Areas of Activity Generic Studies • Charge division • Long-ladder noise Electronics Development • LSTFE readout • KPIX readout Radiation Damage • High-dose electromagnetic irradiation Simulation • Beamline calorimeter reconstruction • Non-prompt track reconstruction

Charge Division Can a longitudinal coordinate be measured with microstrip sensors? Explore with PC-board microstrip mock-up and PSpice simulation

Areas of Activity

Long-Ladder Readout Noise Probe conventional notions about dependence of readout noise on distributed capacitance and series resistance

Standard Form for Readout Noise (Spieler) Series Resistance Parallel Resistance Amplifier Noise (parallel) Amplifier Noise (series) Dominant term for long ladders (grows as L 3/2) Fi , Fv are signal shape parameters that can be determined from average scope traces.

Expected Noise vs. Ladder Length “Lumped element” Load Series noise expected to dominate for narrow (50 m) pitch sensors above ~25 cm long

Sensor “Snake”: Read out up to 13 daisy-chained 5 cm sensors (with LSTFE-1 ASIC) Sensor “Snake” LSTFE 1 chip on Readout Board Can read out from end, or from middle of chain (“center-tap”)

Naïve Prediction vs. Observation “Lumped” Load Observed

Exploring Long-Ladder Noise Results To explore/understand difference between expected and observed, a full network simulation was developed in SPICE by Aaron Taylor ( UNM physics Ph. D. program) and Khilesh Mistry

Comparison with Full Network Model Full network simulation

Further Reduction: “Center-Tapping” Center-Tap Observed Center-Tap Simulated NIM paper in preparation

The LSTFE Microstrip Readout ASIC Designed at SCIPP by Spencer, Schumm et al.

Time-Over-Threshold (TOT) Readout: the LSTFE Pulse-development simulation no loss of accuracy for TOT readout (relative to direct ADC conversion) Targets low-complexity, long-ladder tracking solution Real-time readout stream favorable forward tracking also LSTFE-I prototype relatively successful; LSTFE II under testing. Upgrades relative to LSTFE-I include • 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

Proposed LSTFE Back-End Architecture Low Comparator Leading-Edge-Enable Domain Li Hi Li+1 Hi+1 Li+2 Hi+2 Li+3 Hi+3 Li+4 Hi+4 Li+5 Hi+5 Event Time Li+6 Hi+6 Clock Period = 400 nsec FIFO (Leading and trailing transitions) 8: 1 Multiplexing ( clock = 50 ns)

Minimum ionizing region Time over Threshold ( s) Some early results: TOT respone Very uniform response for large pulses; increased sensitivity in min-i region

More early results: Noise v. Capacitive Load Result at 100 p. F (optimization point): 1375 electrons noise, but without detector resistance (distributed RC network)

Use of the SLAC KPi. X Chip for Tracking SCIPP charged with looking at KPi. X in the one-few f. C range (tracking regime)

0 -Charge Input Offset (m. V) by Channel KPi. X 7 (x 10) Four mis-behaving channels Offset in m. V for no input charge

KPi. X 7 Number of channels with occupancy greater than 0. 1% Use SCIPP pulsedevelopment simulation to assess impact of offset variation Number of channels with efficiency less than 99. 9% Window of operating thresholds Very narrow! Need to consider for further KPi. X versions…

The ILC Beam. Cal: Radiation Damage Studies Reconstruction Studies

The Issue: ILC Beam. Cal Radiation Exposure ILC Beam. Cal: Covers between 5 and 40 miliradians Radiation doses up to 100 MRad per year Radiation initiated by electromagnetic particles (most extant studies for hadron – induced) EM particles do little damage; might damage be 25 come from small hadronic component of shower?

Irradiation Plan Use existing Micron sensors from ATLAS R&D • n-type and p-type • Standard float-zone and Magentic Czochralski • Runs of 0. 1, 0. 3, and 1 GRad for each sample • Runs with samples far from radiator (no hadronic effects) Total integrated dose of ~10 Grad Will assess the bulk damage effects and charge collection efficiency degradation. Sensors Sensor + FE ASIC DAQ FPGA 26 with Ethernet

Charge-Collection Modularization Activity • Can connect multiplicity of Sensor Board modules to PMFE w/out wire-bonding • Requires development of 6 PCB/litho components (Donish Khan; accepted to Stanford Ph. D. program)

BCAL Simulation Alex Bogert: • Geometry and virtual segmentation • Overlay • Mean pair background subtraction • Developing high-energy electron pattern recognition

Average Deposited Energy per Layer Background Signal

Pair Background Energy Fluctuations

Non-Prompt Tracking with the Si. D Explore performance via explicit signature: Metastable stau NLSP (Gauge-Mediated SUSY)

Reconstructing Metastable Staus w/ Si. D Gauge-Mediated SUSY • Large tract of parameters space as stau NLSP • Metastable ( c stau ~ centimeters) is in cosmologically preferred region Process is with

Reconstructing Metastable Staus w/ Si. D Started with: 5+1 layers for inside track 4 layers for outside track New result: Include VTX-only inside track

Measuring Staus with the SID Stau sample: 11. 1 fb-1 of e+e- stau pairs with • mstau = 75 Ge. V • Ecm = 500; = 90 fb • c = 23 cm Background sample: 5. 3 fb-1 combined SM background

Reconstructing Metastable Staus w/ Si. D Focus initially on rdecay = 22 -47 cm… Reconstruct decays by requiring: - Outer hit of inner trk on last VXD or 1 st tracker layer - 1 missing layer between inner & non-prompt trks - Both tracks on the same side of the Barrel (in z) - Tracks have a geometric intersection in the x-y plane And: When inside track has 1 Central Tracker Hit - The sign of the track curvatures match - Non-prompt track curvature larger than the primary Of 897 staus with 6 cm < rdec < 47 cm, 642 staus are reconstructed, of which 592 truth-match

Stau Reconstruction Efficiency Truth-Matched Staus

Signal to Background for 10 fb-1

Signal to Background (10 fb-1) #Prompt Tracks/event p. T of inside track Good separation between signal and background for #prompt tracks/event and inside track pt Require, e. g. , fewer than three prompt tracks

Reconstructing Metastable Staus w/ Si. D Started with: 5+1 layers for inside track; 4 layers for outside track New result: Include VTX-only inside track Next step: Try to use calassisted tracking to get three-hit kinks (dedicated reconstruction by Mallory, Michlin, Bogert)

Wrap - Up Many projects underway: • Charge-division study published • Ladder noise study in preparation for publication • Electronics development proceeding • Simulation studies bearing fruit • New Beam. Cal contribution in full swing • Meaningful research experience for many undergraduates; 8 theses in past three years, including two campus-wide thesis awards

Backup Slides

Areas of Activity