[Halld-cal] Comments on the rms/mean plots

[Elton Smith]

Hi Orlando,

Thanks for the detailed description of rms/mean plots you showed at the 
cal working group meeting. After looking at them more carefully, I think 
I understand them a bit better. Here are a few comments/questions.

o Slide 5. As indicated by Yi, eq 3) should be mean_mui,Gi = 1/16 
Sum1-16 (muik * Gik)   [single summation and no square on the 16].

o Slide 33. This procedure should give you the expected output from the 
light source from the full array. However, the width of the distribution 
depends on a) input light source and b) light intensity. The response 
will obviously track the full width of the light source (I forget what 
it is for your setup). But the width also depends on the statistics. For 
example if the light level is very low (e.g. 1 pixel firing), then the 
width will be very broad. So I think the rms/mean for the amplitude is a 
reflection of the source properties (distribution and light intensity) 
more than a property of the sensors themselves. Therefore, I am not sure 
it addresses issues related to the specifications of the sensors. 
However, it does indeed represent what we might expect from a 
measurement of that input source with the SiPM arrays. It would be quite 
interesting to check these distributions for situations where the number 
of pixels firing is fairly large, which is what we expect in the actual 
experiment. For a 1 GeV particle there should be about 5000 pixels firing.

Cheers, Elton.

-- 
Elton Smith
Jefferson Lab MS 12H5
12000 Jefferson Ave
Suite #16
Newport News, VA 23606
(757) 269-7625
(757) 269-6331 fax