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Cosmic Tests of Trackers 1 & 2

Cosmic Tests of Trackers 1 & 2. 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.

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Cosmic Tests of Trackers 1 & 2

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  1. Cosmic Tests of Trackers 1 & 2 M.Ellis & B. Freemire - CM24 - 2nd June 2009

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

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

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

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

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

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

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

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

  10. Light Yield Photo Electrons M.Ellis & B. Freemire - CM24 - 2nd June 2009

  11. 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 % ~ 97% of tracks have 5 points M.Ellis & B. Freemire - CM24 - 2nd June 2009

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

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

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

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