Transcript Cryo and AFE IIt Update Fiber Tracker Meeting April 6, 2006 Imperial College A.

Cryo and AFE IIt Update
Fiber Tracker Meeting
April 6, 2006
Imperial College
A. Bross
Cryo Update I
 The cryo-system for the VLPCs has been operated extremely
reliably and stably from May 05, through the end of the KEK
TB and now for about 2 months again at Fermilab
 However, it was felt that the thermal-link design could be
made more robust

A bolted concept has now been detailed and will be used in all
subsequent systems


Modulo one problem
Vacuum tests on the bolt to envelope weld were successful
 The drawing package is complete and we have awarded the bid
to Ability Engineering for $140k for 4 systems

Does not include




Cryo-coolers
Temperature controlers and sensors
Lid Heater circuitry
Cassette He gas system
Cryo Update II
Cryo Update III

However II

Need to solve an assembly problem at upper thermal link
Cryo Update IV
 We recently did a tilt test
of the system
 Operation at 25o off
normal was fine

We observed an
approximately 0.3K
temperature increase at
stage II (5.2  5.5K)
 The Cryo-cooler efficiency
is degraded when it is
operated off-vertical, but
this does not present a
problem for the MICE
VLPC system
Cryo Update V

Excellent temperature stability (spec is  50 mK)
Cryo Update VI
LHC Power vs Cold End Temperature
Upright
Tilted
20%
18%
16%
VLPC Heater Power
14%
12%
10%
8%
6%
4%
2%
0%
6.1
6.15
6.2
6.25
6.3
Cold End Tem perature (K)
6.35
6.4
6.45
 However looking at both
cassettes we see that
the left-hand cassette
is on the edge of being
“in control”
 Even in the upright
position, the LHC will
be on the edge with
the cryo-cooler
compressor operating at
50HZ
 REALLY need to solve
the thermal link
problem
AFE IIt Update
 The AFE IIt pre-production boards (15) have now all arrived
at Fermilab and 5 or 6 are under test
 The first boards came up very quickly


In about 1 hour
No green wires!
 TriPt testing is done


Yield is about 80%
More than enough chips for D0 + MICE + Spares for both
experiments

Plus second pass could yield more
 Expect Production Order to be released soon


New issue with discriminator threshold spread
About 10 week lead for delivery of all boards
 But many will arrive earlier
 The critical issue for MICE is MICE-specific firmware
development for AFE IIt

NOT a Trivial amount of work
AFE IIt
LED Spectra:
AFE1
11/6/2015
JW@FTG,
2006Mar21
AFEII
AFE IIt Discriminators
 Turn on
spread seen
on the
platform –
much wider
than
expected
11/6/2015
AFE IIt Discriminators II
 More of
same
11/6/2015
AFE IIt Discriminators III
 Change in
AFPGA
firmware
– now
fixed!
11/6/2015
Issues that still Need some Thought
 AFE IIt board temperature and bias calibration

Does MICE need a test stand (like D0 has) to do this operation?
 LED pulser data

Plan to dismount wavguides and mount a LED pulser or excite the
fibers with blue LEDs?
 New LVSB Board

Not likely. Existing board looks OK. 6 new boards are being
assembled now.

Firmware development still might be needed
– May be able to get support for this from Fermilab CD
 Rate

If we keep analog and timing information we are limited to:

 250 muons per msec of spill
– It is possible that clever (extreme) programming of the AFE IIt can push
this up a bit.

If we drop analog and timing and only use discriminators, we can
run at 7 MHz.