Re: Bcal power (fwd)

["George Lolos" <George.Lolos@uregina.ca>]

Hi Simon:

All the SiPM's from SensL so far that come out of the same Si wafer
treatment have very stable breakdown voltages.  In fact, the observation
is a fixed breakdown voltage within less than 1 V range.  On the other
hand, for the thousands of SiPM's we will need, we should have some
limited capability of fine tuning the bias within a 1-2V range from a
nominal for a group of sensor arrays.  Since each array will be checked
individually before installation, we can select them in groups of a
fixed operating voltage at which all have the same gain and apply a
group adjustment to match their gain to that of another group if
necessary.  

I will get more definitive feedback from SensL (I cc this to Sensl) but
I don't foresee the need for individual voltage adjustments.

George

>>> Simon Taylor <staylor@jlab.org> 03/15/07 12:18 PM >>>


---------- Forwarded message ----------
Date: Thu, 15 Mar 2007 14:07:17 -0400
From: Joe Beaufait <beaufait@jlab.org>
To: halld-tracking-hw@jlab.org
Subject: Bcal power

Fernando and I were discussing the Bcal bias voltage control and I was
wondering how much control is needed. Do we want individual channel
control, one bias voltage for all the silicon pmts, or something in
between? Please give me input, or think about it for discussion on the
28th.
Thanks
Joe B.