Log entry time 03:19:31 on September27,2005

Entry number 156157

Spectrometer runs to optimize HV on HAPPEX detector and
increase our efficiency to see possible low energy background.

Run .... PMT HV (Left/Right) .... Resp. Trig Rate (L/R)

2760 .... 1900 / 1800 ...... 126K / 94K
2761 .... repeat
2762 .... 1950 / 1850 ...... 222K / 212K
2763 .... 2000 / 1900 ...... 228K / 242K
2764 .... 2050 / 1950 ...... 245K / 264K
2765 .... 2100 / 2000 ...... 246K / 271K
2766 .... 2150 / 2050 ...... 248K / 291K
Stopped increasing Left HV
2767 .... 2150 / 2100 ...... 248K / 332K
2768 .... 2150 / 2150 ...... same / 390K
Left arm seems to 
2769 ... repeat.
Decide to crank up to 2200V, the max (I think). Doesn't trip HV.
2770 ..... 2200 / 2200 ..... 259K / 449K

Fig 1 shows how the rates rise with HV.
Fig 2 shows how the increased HV "pulls out" the tail near pedestal.
This looks better.