1. Thought on SCIPP’s Participation in SiLC Test Beam Activities
SiLC Meeting
Barcelona, Spain (by telephone)
December
Bruce Schumm

2. What might we want to demonstrate by 2011 (partial list)?
Power Cycling
Long-ladder operation / system noise
Efficiency vs. occupancy for long ladder
Point resolution (vs. incident angle)
Timing resolution
Rate capability / readout scheme
Propagation effects (distance from readout chip)
* Item in green can only be assessed with high-energy test beam, but some others might benefit

3. Faking the Magnetic Field
Michael Young, UCSC
Resolution
Track Angle
Different track angles for 5T field (B-Field) or 180 mrad tilt with no B-field (Tilted).

4. Faking the Magnetic Field
Michael Young, UCSC
Resolution
Magnetic Field (T)
Different B-Fields (B-field) or detector tilt to simulate Lorentz angle (Tilted)
 Do we need high-field test beam facilities?

5. SiLC will want to develop both new sensors and new readout
It would be best to test new sensors with established readout and new readout with established sensors
IDEA: Might SCIPP be able to provide assemblies (ladders) of establihsed sensors borrowed from other experiments for readout groups to use in testing their electronics?
Problem: ILC optimization points to
Long Ladders – must worry about parallel noise
Long Shaping Time – must worry about leakage current
High Resolution – must worry about strip/readout pitch

6. Helmuth Spieler’s Rule of Thumb for Equivalent Noise Charge Qn (p 148 of his Semiconductor Detector Systems):
where:
Id = detector leakage current
Rp = parallel resistance (bias resistance)
C = effective capacitance
= shaping time
Ideally, Qn < 2% of a min-i signal, or roughly 500 e-.
At  = 2 sec, this limits Id to be less than ~ 10 nA and Rp to being greater than ~ 5 M, where individual bias resistors in the ladder add in parallel.

7. Existing Sensors
7 m resolution goal suggests ~50 m is correct scale for readout pitch
LHC sensors tend to have larger (~100 m pitch)
Tevatron upgrade vertexing inner layers have correct pitch
D0 L2-5 sensors have 30 m pitch with 60 m readout
CDF L00 sensors have 25 m pitch with 50 m readout

8. D0 Layer 2-5 Sensors
Very large (~ 1000) supply
Characterization data-sheets available
Leakage currents ap-pear acceptable (spec is ~ 10 nA/strip; actual is much better)
Polysilicon bias resistor rather small

9. CDF Layer00 Sensors
More limited supply (???; have 20 in hand, but can only keep 10)
Will do characterization ourselves this winter
Leakage current spec OK
Polysilicon bias resistor OK
(Both Rb and Ileak are a little marginal, but should be fine for initial testbeam

10. So, CDF L00 detectors looks possible, but only one at a time…
“Long” ladder is one 8cm sensor and a big discreet capacitor?
Or: build long ladder by bonding a single 8 cm sensor to low-leakage, large-bias-resistor, coarse-pitch detectors (GLAST would be a possibility) to allow for antenna, transmission line effects
Or: identify more appropriate existing sensor (?)

11. Particularly for long ladders, angle of incidence can really matter
 I believe it to be very important that we be able to rotate ladder around axis perpendicular to the beamline

12. What might SCIPP bring to a testbeam run for the mutual benefit of SiLC? (enlightened self-interest)
Long (or “long”) ladder with well-understood sensor?  would need to develop front- and back-end specs for those wishing to plug electronics into it and to read out the electronics
Alternatively, could produce several and ship them?
Rotating jig for SCIPP ladder(s)? Would depend on availability of funding (“Supplemental” proposal is pending)