Cosmic Tests of Trackers 1 & 2

1M.Ellis & B. Freemire - CM24 - 2nd June 2009

Progress since CM23

Cryostats 3 and 4 shipped from Fermilab to RAL.

All four cryostats set up in lab 7 and cooled down.

Major power failure at RAL caused some problems which took a while to fix.

Since then cryostats 3 and 4 have again been cooled down.

Cryostats 1 and 2 will remain at room temperature until we are ready to read out both trackers with DATE due to limited remaining time on the cold heads before a service is needed.

2M.Ellis & B. Freemire - CM24 - 2nd June 2009

LED Calibration

Initial data taken with the LED in lab 7 indicated that the code to chose the optimum bias for the VLPCs had chosen values that were too high for the tracker 2 VLPC cassettes.

The code was modified and re run on the fits made at Fermilab and new bias values were determined (that agree better with D0 values).

A new set of high statistics LED data was taken on all four cassettes (at 9.0 K and 9.5 K).

With the exception of a couple of modules (which we are not using for readout) the cassettes have a good response and very few dead channels.

3M.Ellis & B. Freemire - CM24 - 2nd June 2009

Tracker 2

Tracker 2 assembly was completed in lab 7 and following the LED data taking, the external waveguides were hooked up to the best 25 modules on the four cassettes.

Two of the four new (as of last year) trigger scintillators were setup to make a cosmic ray trigger similar to that in R8.

Early results are promising (see next slides), however we still need to fine tune the trigger delay.

There is also an as-yet unexplained low efficiency of triggers containing tracks, however this appears to be due to the trigger and not the tracker.

4M.Ellis & B. Freemire - CM24 - 2nd June 2009

Safety & Alarms

The VESDA smoke detection system and alarms used in R8 have been hooked up to the auto-dialler as they were in R8.

In addition, there is now an alarm produced if any of the compressors stop working (as happened when the fuse blew for our chiller unit).

A shut-off valve has been installed between the manual valve and the turbo pump on each cryostat so that in the event of a power failure the insulating vacuum will not degrade as quickly as it did during the power failure.

5M.Ellis & B. Freemire - CM24 - 2nd June 2009

Decoding

Ben was set the task of implementing the decoding for tracker 2 using that made by Aron for tracker 1 and the details from Geoff and Roger of the waveguide connections.

The first version had a 1-128 way connector around the wrong way (due to an inherited difference between trackers 1 and 2 from the tracker 1 file) and the revised version appears to be correct!

6M.Ellis & B. Freemire - CM24 - 2nd June 2009

First Results

All of the following results are preliminary (they are one week old at most!), but so far reasonably encouraging: Triplet Residuals & Alignment Track fit residuals Light Yield Space point efficiency Dead channels Event displays

7M.Ellis & B. Freemire - CM24 - 2nd June 2009

Triplet Residuals & Alignment

All five station triplet internal residuals were consistent with 0 without the need for any adjustment from the nominal plane positions within a station!

Stations 2-4 were aligned in the X-Y plane to be centred on the axis defined by stations 1 and 5.

For now the nominal station spacing is being used, will use the CMM data later on (for tracker 1 this was a VERY small correction).

Shifts of 10s-100s of microns were required (the largest shift was under 1 mm).

8M.Ellis & B. Freemire - CM24 - 2nd June 2009

Track Fit Residuals

9M.Ellis & B. Freemire - CM24 - 2nd June 2009

Light Yield

10M.Ellis & B. Freemire - CM24 - 2nd June 2009

Photo Electrons

Space Point Efficiency

Calculated in the same manner as previously reported for tracker 1.

Station 1: 99.86 ± 0.06 % Station 2: 99.71 ± 0.08 % Station 3: 99.62 ± 0.09 % Station 4: 99.53 ± 0.10 % Station 5: 99.38 ± 0.13 %

11M.Ellis & B. Freemire - CM24 - 2nd June 2009

~ 97% of tracks have 5 points

Dead Channels

12M.Ellis & B. Freemire - CM24 - 2nd June 2009

3 Dead Channels

Event Displays

13M.Ellis & B. Freemire - CM24 - 2nd June 2009

Next Steps

Continue with the timing scan. Investigate (and fix) the low fraction of

triggers that have a track. Take large statistics at the optimum trigger

delay. Move to the DATE DAQ system. Write code to unpack VLSB data from the

DATE file (some needs to go in the unpacker, some in G4MICE, most of the needed code already exists).

Test readout and reconstruction of both trackers.

Move the tracker systems to the MICE hall.14M.Ellis & B. Freemire - CM24 - 2nd June 2009