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Hi Alex,<br>
<br>
A few weeks ago, Eugene mentioned that you were going to perform
additional simulations about the radiation levels in the tagger hall
so we could settle on the racks placement. Did you have a chance to
look into this?<br>
<br>
Thanks and best regards,<br>
Fernando<br>
<br>
<br>
On 12/9/2013 10:56 AM, Fernando J Barbosa wrote:
<blockquote cite="mid:52A5E82D.50706@jlab.org" type="cite">
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Hi Hovanes,<br>
<br>
My plan is to use a mini MPOD with two modules, one is the
familiar 8V and the other is a 120V. Both are Wiener MPODs and I
can segment into 6 TAGM backplane feeds. So, the controls are the
same as the rest of the Hall D MPODs. This solution will cost less
than $15k. I will distribute the plan shortly.<br>
<br>
Best regards,<br>
Fernando<br>
<br>
<br>
On 12/9/2013 10:51 AM, Hovanes Egiyan wrote:
<blockquote cite="mid:52A5E6F6.6010207@gmail.com" type="cite">
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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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