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Hi Richard,<br>
<br>
In reference to the BCAL and taking Yi's measurements in Hall A
regarding radiation damage, we settled on a maximum of 10mA for 10
arrays or 160 cells (3mm x 3mm). This works out to 62.5uA per cell
and your estimate is higher by a factor greater than 10. What is
your plan for annealing the SiPMs? Frequency?<br>
<br>
Did you look into any supplies that might fit your requirements? I
recall that each backplane of the TAGM has a single bias supply
input, correct? This would be important in considering a
multi-channel supply system. Please send me your latest drawings on
the TAGM system and its installation in the Tagger hall.<br>
<br>
Best regards,<br>
Fernando<br>
<br>
<br>
On 12/5/2013 10:50 PM, Richard Jones wrote:
<blockquote
cite="mid:CABfxa3R6K4-RoiSZLEomBLOYhxF4_6x8_MS3XiB_ozpuT5VWVA@mail.gmail.com"
type="cite">
<div dir="ltr">Hello Fernando,
<div><br>
</div>
<div>I am spec'ing the Vbias supply capacity at 500mA to allow
for the maximum SiPM draw current that is permitted by the
bias voltage supply system. Initially we expect the average
current to be around 15 mA at full intensity (2.2 uA electrons
on 20 micron diamond) but that it will increase gradually over
time due to radiation damage. To get the maximum current
spec, I imagine the worst possible circumstances under which
the radiation damage might accumulate faster than expected,
and ask how much current could we sustain across all channels
before the resolution and efficiency degrade significantly due
to dark current. The answer to that is approximately 800uA
per channel, which totals about 400mA from the supply. I
rounded that up to 500mA. </div>
<div><br>
</div>
<div>-Richard Jones</div>
</div>
<div class="gmail_extra"><br>
<br>
<div class="gmail_quote">On Thu, Dec 5, 2013 at 4:51 PM,
Fernando J Barbosa <<a moz-do-not-send="true"
href="mailto:barbosa@jlab.org">barbosa@jlab.org</a>>
wrote:<br>
<blockquote class="gmail_quote">Hi Richard,<br>
<br>
I looked at the specs and the bias supply current seems to
be excessive at 500mA. What's the reason for this?<br>
<br>
Best regards,<br>
Fernando
<div class="HOEnZb">
<div class="h5"><br>
<br>
<br>
On 12/5/2013 3:33 PM, Richard Jones wrote:<br>
<blockquote class="gmail_quote">
Hello Alex,<br>
<br>
Here is a draft of the specs for the microscope
readout dc power supplies. They can be a single unit
for each of 3 levels, or a few lower-capacity supplies
in tandem with the same total output capacity. Please
request justification for any of the specs. One thing
we do not spec here, but think would be useful, is
separate delivery and sense terminals for each output.
We have separate pins on the backplane connector for
this purpose.<br>
<br>
<a moz-do-not-send="true"
href="http://zeus.phys.uconn.edu/wiki/index.php/Microscope_Electronics#Power_Supply_Requirements">http://zeus.phys.uconn.edu/wiki/index.php/Microscope_Electronics#Power_Supply_Requirements</a><br>
<br>
-Richard Jones<br>
</blockquote>
<br>
</div>
</div>
</blockquote>
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<br>
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</blockquote>
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