[Halld-tagger] microscope beam test

[Richard Jones]

Alex,

I will keep the idea of another beam test in the Spring in mind.  We have the new preamp design finished, and a run of 3 new pcb's is out on order to the manufacturer now.  A new order of 35 Hamamatsu SiPM's has just gone out as well.  We should have two new completely instrumented preamp boards in the lab by the end of the year.  They have the same form-factor and pin-out as the original, so they can go straight into the prototype detector and work right away.

I will plan to fire up the prototype with the existing electronics on the bench, and measure the pedestal lineshape to extract the single-pixel response.  I have a few things I wonder if you could look up for me.

 1. the discriminator thresholds on all of the SiPM 8 signals (chan. 0-4, 12-14).  If they changed, the date/times when they were changed.
 2. the gain setting (adc chan/mV) on each channel in the FADC.

Knowing these things will help me cross-check all of my assumptions that I used in extracting the number 350 pixels from the adc spectra.  I agree that the detected pixel count is an important thing to make sure we got right.

Let's plan to review these results at one of our biweekly meetings and assess what risks still exist in our design, which may be reduced by a second run in Hall B in 2012.

-Richard Jones

On 11/3/2011 9:34 AM, Alexander Somov wrote:
> Hello Richard,
>
> Yes, I agree. I think that once we confirmed the
> amount of light in the scintillator fiber, the
> rest of tests can be done on the test bench.
>
> ( though if you get some part of the detector ready
> by spring, we can test it with the beam again -
> I volunteer to help with the tests..., but again,
> it's up to you )
>
> Cheers,
>          Alex
>
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