User name NIlanga
Log entry time 00:19:16 on March20,2006
Entry number 167525
Followups:
keyword=bigbite singles efficiency: 85%Use 1.5 GeV H2 elastic run 2485 to estimate bigbite singles efficiency, taking into account the pre-scale factors for different trigger types.
The momentum optimization is not good at the edges: see the plot of p vs. x. So I am using an asymmetric cut -0.04-0.25, to catch all of elastic and not much of delta.
I first did this with a cut on the full target length and assuming that the effective solid angle is 75 msr.
For this I get a rate of 18.5 Hz/muA and the total charge for run was 3935 mC. So we expect to see about 73k elastic electrons.
The numbers are:
Only D.bit3 = 9334 - N_3
Only D.bit2 = 2601 - N_2
D.bit3 and D.bit2 = 1043 - N_23
I use the following formula to get the total number of singles:
= {N_2*PS2 + (N_23*PS2 + N3) / coin_Eff}*LT
Where coin_eff is the coincidence trigger efficiency. LT is the live-time correction (thinking positive!) = 1.05
From this I get N_actual = 61.9 k
So the singles efficiency comes out to be = 61.9 / 73. = 85 %
(Not too bad !)
I repeated the calculation with a +/- 10 cm target cut assuming a solid angle of 100 msr. Here I get an efficiency of about 80%.
Including radiative correction will make these numbers go higher.
FIGURE 1
