Cryo and AFE IIt Update

Fiber Tracker MeetingApril 6, 2006

Imperial CollegeA. 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 mK)

Cryo Update VI

LHC Power vs Cold End Temperature

0%

2%

4%

6%

8%

10%

12%

14%

16%

18%

20%

6.1 6.15 6.2 6.25 6.3 6.35 6.4 6.45

Cold End Temperature (K)

VL

PC

Hea

ter

Po

wer

Upright Tilted

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

04/20/23

LED Spectra:

AFE1 AFEII

JW@FTG, 2006Mar21

04/20/23

AFE IIt Discriminators

Turn on spread seen on the platform – much wider than expected

04/20/23

AFE IIt Discriminators II

More of same

04/20/23

AFE IIt Discriminators III

Change in AFPGA firmware – now fixed!

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.