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Fi , Fv are signal shape parameters that can be determined from average scope traces.
Dominant term forlong ladders (grows
as L3/2)
Expected Noise vs. Ladder Length
Series noise expected to dominate for narrow (50 m) pitch sensors above ~25 cm long
“Lumped element” Load
Sensor “Snake”: Read out up to 13 daisy-chained 5cm sensors (with LSTFE-1 ASIC)
Sensor “Snake”
LSTFE1 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”
NIM paper in preparation
Center-Tap Observed
Center-Tap Simulated
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)
Real-time readout stream favorable for 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
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)
Some early results: TOT respone
Tim
e ov
er T
hre
shol
d (
s)
Tim
e ov
er T
hre
shol
d (
s)
Minimum ionizing region
Very uniform response for large pulses; increased sensitivity in min-i region
More early results: Noise v. Capacitive Load
Result at 100 pF (optimization point): 1375 electrons noise, but without detector resistance (distributed RC network)
Use of the SLAC KPiX Chip for Tracking
SCIPP charged with looking at KPiX in the one-few fC range (tracking regime)
0-Charge Input Offset (mV) by Channel(x
10)
Offset in mV for no
input charge
Four mis-behaving channels
KPiX 7
Window of operating thresholdsVery narrow!Need to consider for further KPiX versions…
Number of channels with occupancy greater than 0.1%
Number of channels with efficiency less than 99.9%
KPiX 7
Use SCIPP pulse-development simulation to
assess impact of offset variation
The ILC BeamCal:
Radiation Damage Studies
Reconstruction Studies
25
The Issue: ILC BeamCal Radiation ExposureILC BeamCal:
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 come from small hadronic component of shower?
26
Irradiation PlanUse 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 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 SiD
Explore performance via explicit signature: Metastable stau NLSP (Gauge-Mediated SUSY)
- Outer hit of inner trk on last VXD or 1st 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 planeAnd: 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 6cm < rdec < 47cm, 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)
Good separation between signal and background for #prompt tracks/event and inside track pt
5+1 layers for inside track; 4 layers for outside track
New result: Include VTX-only inside track
Next step: Try to use cal-assisted tracking to get three-hit kinks (dedicated recon-struction 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 BeamCal contribution in full swing• Meaningful research experience for many undergraduates; 8 theses in past three years, including two campus-wide thesis awards