E0prime 2004 data summary page

tb2004 homepage for E0prime links and daily run summary
Logbook (100MB) 3 June - 6 Sep 2004
E0prime temperature data

E0prime data was taken during 5 beam periods in 2004, primarily to investigate crystal radiation hardness.
E0prime comprised one supercrystal, SC03, with 25 crystals (10 BTCP, 15 SIC) and VPT readout, for the first 2 periods.
A second SC, SC04, was added from the 3rd period, with 15 crystals (3 BTCP, 2 Apatity, 10 SIC) with APD readout.
2 of the SIC crystals in SC04 were 'good' crystals from the Jan 2004 production. 8 of the SIC crystals were from the 2nd
but 'bad' production of May 2004, and are thought to have been contaminated from crucibles used for other types of crystals.
As a consequence these crystals were relatively radiation soft.

The SCs were read out with barrel VFE cards (approx 8-10k e- noise), to FE cards which were read out to Rose10 cards
in the control room.

Particular observations 
During the first period, and in particular during the 2nd period, the VPT response in SC03 was observed to change significantly
due to beam rate effects. As an example, from the 'Latest announcements' log, tb2004 homepage for Fri June 18, period 2:
          16.00: Back to 0mrad setting on T2
          Irradiating xtal 24
          09.46, 100 Hz laser suspended this morning, after run 69826
               - saw repeat of rapid VPT response change seen in period 1
          13.40, after run 69849, re-introduced 100 Hz laser, signal returns to previous level in ~1h
          15.11, 100Hz laser turned off, after run 69860
          15.20, 100Hz laser turned on again, after run 69862

         
The effect has since been replicated in the laboratory [1] [2].
The effects are most pronounced when VPTs are operated at low beam rates following periods of high beam rate activity.
The VPT rate effects were found to be minimized by running laser pulses (120GeV equivalent) at 100Hz into SC03 as shown in the plot above.
The 100Hz laser pulses provide the equivalent of 'constant' high level beam rates during VPT operation which help stabilize the VPTs. 
Data from the periods with the 100Hz laser in period 2 should be relatively reliable.
Data in period 1, in particular the initial calibrations, before high beam operation (>2k/burst), should be reliable.  

Comments, questions? Contact Dave Cockerill
29.7.2005