Make New Entry, Make Followup Entry
User name gjin
Log entry time 12:19:01 on April30,2009
Entry number 269941
Followups:
keyword=MWDC thresholds and HV scan planbelow is the hit efficiency and hit time of run 1518, with the run condition HV=-1500V and thresholds are 5V for both chambers.
Thresholds were 2.5V and 4.5V in pi0, although they were recorded as 5V in halog due to the problem with the threshold power supply.
background rates are (in counts/second)
u1 97870.9
u1p 102140
u2 103857
u2p 97155.7
x1 95383
x1p 91137.3
x2 103245
x2p 101500
v1 96610.5
v1p 94125
v2 106811
v2p 105014
background rates are reflected in the hit time graph. beam current were 2.4 uA in this run, so if we want to run 12 uA in future e'd experiment, we will get background rates 5 times higher, that means that the pleateu in the hit time graph is 5 times higher but not the peaks.
hit efficiency were greater than 99%, and I expect them to be higher if the thresholds are lower.
another reason but lower thresholds is that they cost less time walk effect
so I suggest scanning around -1500V for HV, and (2.5V, 4.5V) for thresholds.
FIGURE 1
FIGURE 2
