Transcript Michael Young, UCSC

Thought on SCIPP’s Participation
in SiLC Test Beam Activities
SiLC Meeting
Barcelona, Spain (by telephone)
December 19 2006
Bruce Schumm
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
Faking the Magnetic Field
Michael Young, UCSC
Track Angle
Different track angles for 5T field (B-Field) or 180 mrad
tilt with no B-field (Tilted).
Faking the Magnetic Field
Michael Young, UCSC
Magnetic Field (T)
Different B-Fields (B-field) or detector tilt to simulate
Lorentz angle (Tilted)
 Do we need high-field test beam facilities?
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
Helmuth Spieler’s Rule of Thumb for Equivalent Noise
Charge Qn (p 148 of his Semiconductor Detector
Systems):
2
2
 2 C2
e 2 ns
 e 
5  e k  
4
Qn  12
I d  6 10 
 3.6 10 
2
2
en 


nA

ns
ns
R
(
pF
)
(
nV
)
/
Hz



 p


2
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.
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
D0 Layer 2-5 Sensors
Very large (~ 1000) supply
Characterization datasheets available
Leakage currents appear acceptable (spec is
~ 10 nA/strip; actual is
much better)
Polysilicon bias resistor
rather small
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
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, coarsepitch detectors (GLAST would be a possibility) to
allow for antenna, transmission line effects
 Or: identify more appropriate existing sensor (?)
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
What might SCIPP bring to a testbeam run for
the mutual benefit of SiLC? (enlightened selfinterest)
• Long (or “long”) ladder with well-understood
sensor?  would need to develop front- and backend 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)