Minutes of Quick Calorimetry Meeting  28-2-96.


Present:  DJAC, PSF, BWK, ALL, MS.


DJAC  PPARC visited CERN Tues/Wed. CMS put on a display in the test beam
      area. Kate McK. gave a presentation, congratulations from Ken Pounds.
      PPARC seemed favourably impressed.
      Meeting of PPARC at CERN on Weds., CMS and ATLAS were written into
      the 5 year business plan.


ALL   Working on beam hodoscope, should get fibreoptic grid today.
      PC should arrive today. AutoCad on it's way.
      Hall probe will have to be inserted in BM1 at next shutdown, will
      try and arrange for output to chart recorder.
      Chase RS/EB for APD irradiation work.
      Will try and install copper block in brass box to speed up crystal
      temperature stabilisation.


MS    Still chasing noise, not perfect but need to push crystal scans.
      Related positions with new stepper system.
      Scanned 1342 with old veto in then veto out, momentum scan done
      without old veto. 1342 now finished.
      New crystal (1264) mounted last night, will scan over the weekend.
      Weds/Thurs next week scan other crystals, before return to CERN on
      Thursday.


PSF   Sheffield last week, investigated the effect of process change on 
      melt. Made test blocks of standard mix (2) 10mm thick, this has a
      16 times faster cooling rate than 20mm thick. 2 blocks had ground
      /not ground HfF4 crystals. Results looked similar but the not ground
      crystals produced a slightly better result (P319B) than the ground
      (P321) which had some crystallisation around nucleation centres.
      Next try pouring from below surface avoiding avoiding surface
      mixing with melt.
      In parallel tried a melt refluoridising with Ammonium hydrogen
      difluoride. This produced red samples, one of which was improved by
      remelting in an oxygen atmosphere.
      Will scan new blocks on test beam.


BWK   Doing air gap simulations with preshower in front of end cap with
      photons of various energies 45 deg to endcap.
      Showed plot of cluster shape at 500 GeV.
     
      50GeV  No preshower    res 0.5% } 9x9     0.5% } 5x5
             With preshower  res 1.5% }         1.7% }

      500GeV   Looks better   No preshower      0.7% } 5x5
                              With preshower    0.6% }    


Laurie Lintern  5-3-96.