Download - R&D Towards a Linear Collider Detector
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, McFadden, Michlin, Mistry, Moreno, Newmiller, Ramirez, Schier**, Taylor*, Thompson*
* Senior thesis completed** Campus award for senior thesis
Areas of ActivityGeneric 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
Amplifier Noise (series)Amplifier Noise (parallel)
Parallel Resistance
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)
Targets low-complexity, long-ladder tracking solution
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)
Reconstructing Metastable Staus w/ SiDGauge-Mediated SUSY
• Large tract of parameters space as stau NLSP
• Metastable (cstau ~ centimeters) is in cosmologically preferred region
Process is
with
~~ee
~
G~
cmc 23
Reconstructing Metastable Staus w/ SiD
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 GeV
• Ecm = 500; = 90 fb
• c = 23 cm
Background sample:
5.3 fb-1 combined SM background
Reconstructing Metastable Staus w/ SiDFocus initially on rdecay = 22-47 cm…
Reconstruct decays by requiring:
- 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
Require, e.g., fewer than three prompt tracks
#Prompt Tracks/eventpT of inside track
Reconstructing Metastable Staus w/ SiDStarted with:
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
Backup Slides
Areas of Activity