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<div class="moz-cite-prefix">Hi Richard, <br>
what type of controls is needed for these? Do we need to be able
to remotely <br>
control them, turn them on/off, power cycle them? <br>
Hovanes. <br>
<br>
On 12/09/2013 10:37 AM, Fernando J Barbosa wrote:<br>
</div>
<blockquote cite="mid:52A5E3B3.5020505@jlab.org" type="cite">
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Hi Richard,<br>
<br>
OK, looks good. I will look at options for the supplies.<br>
<br>
Thanks and best regards,<br>
Fernando<br>
<br>
On 12/9/2013 10:28 AM, Richard Jones wrote:
<blockquote
cite="mid:CABfxa3QLVFh7-c4hXrerYvFccsA+mZYDqg=TgPK4+2CB54yN5g@mail.gmail.com"
type="cite">
<div dir="ltr">Fernando,
<div><br>
</div>
<div>Our background study showed that we could continue to
function for 10 years of high-rate running without
annealing, just allowing the dark rate to increase at the
rate that was measured in Hall B and allowing the supply
current to increase. Under the zero-shielding scenario,
just leaving the electronics unshielded in the tagger hall,
we estimated that we would reach the point where we would
need to do something (eg. anneal or replace the SiPM's)
after 10 years of high-rate running. The usual assumptions
were applied (100 days of running per year, standard 20
micron diamond, 12 GeV electrons at 2.2 microAmps). With
shielding, we expect to reduce this figure by a factor of
5-10 (the simulation gave a factor around 8), so we should
be able to run for the duration of GlueX without annealing.</div>
<div><br>
</div>
<div>I agree with you that we can segment the supplies. Each
of them can be split up to 6 ways, because there are 6
identical backplanes in the system. The specs we posted
were for the total sum of all 6 backplanes.</div>
<div><br>
</div>
<div>-Richard J.</div>
</div>
<div class="gmail_extra"><br>
<br>
<div class="gmail_quote">On Mon, Dec 9, 2013 at 9:52 AM,
Fernando J Barbosa <<a moz-do-not-send="true"
href="mailto:barbosa@jlab.org">barbosa@jlab.org</a>>
wrote:<br>
<blockquote class="gmail_quote">
<div bgcolor="#FFFFFF" text="#000000"> Hi Richard,<br>
<br>
Certainly the rates in the tagger are higher but what is
your planning for annealing the SiPMs? I am just curious
given the higher rates.<br>
<br>
Regarding the power supplies, you mentioned the
possibility of having three supplies instead of one for
the whole system. Is it possible to consider further
segmentation? One channel per backplane? Do you have a
document that shows the whole system as installed? The
issue is also related to the space available under the
magnet.<br>
<br>
Best regards,<br>
Fernando
<div>
<div class="h5"><br>
<br>
<br>
On 12/6/2013 10:09 AM, Richard Jones wrote:
<blockquote type="cite">
<div dir="ltr">Fernando,
<div><br>
</div>
<div>These estimates for the BCal do not apply
to the TAGM, where the rates are much higher.
We can set up a meeting to discuss this
further if you feel we need it. We worked out
these rates back during the design phase for
the readout electronics, and had them reviewed
within the photon beam working group. Also
keep in mind that the neutron flux is much
higher in the tagger hall than in the
experimental hall. On the other hand, the
TAGM can operate efficiently at much higher
single-pixel rates than can a calorimeter
because it is not producing an energy
measurement, but only time, and the photon
statistics are high, <n> = 350-400
within a 15ns window. We are shielding these
electronics, but we only expect to cut down
the neutron flux by about a factor 10-20 in
this way. Alex Somov did the neutron rates
and shielding studies for us, and can provide
more details in this regard.</div>
<div><br>
</div>
<div>-Richard J.</div>
</div>
<div class="gmail_extra"><br>
<br>
<div class="gmail_quote">On Fri, Dec 6, 2013 at
9:04 AM, Fernando J Barbosa <<a
moz-do-not-send="true"
href="mailto:barbosa@jlab.org">barbosa@jlab.org</a>>
wrote:<br>
<blockquote class="gmail_quote">
<div bgcolor="#FFFFFF" text="#000000"> 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
<div>
<div><br>
<br>
<br>
On 12/5/2013 10:50 PM, Richard Jones
wrote:
<blockquote 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>
<div><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>
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