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Hi Tegan,<br>
<br>
Sorry we missed the meeting this morning. I will try to provide
answers/comments where I can. Others can also provide feedback.<br>
<br>
= New code = <br>
* Poisson statistics smearing still needs a value for the energy of
one dark hit.<br>
<br>
Attached is a script and plots of a single pixel firing, with the
normalization of summed energy of 0.31 MeV/pixel. Note, however that
his depends on several factors. This is an average value for energy
deposited in the middle of a module. Of course the actual amount of
energy deposited with that amplitude will depend on the position of
the energy deposition. Also, I have used a gain factor of 0.046
MeV/integral count. But these vary quite a bit from cell to cell.
See Will's log entry detailing the gain factors obtained for the
fall run:<br>
<a class="moz-txt-link-freetext" href="https://logbooks.jlab.org/files/2015/03/3328508/BCAL_Calib_Update_Mar20.pdf">https://logbooks.jlab.org/files/2015/03/3328508/BCAL_Calib_Update_Mar20.pdf</a>.<br>
However, the question itself regarding what energy corresponds to a
single pixel is a little misleading. If one is simulating dark hits
(i.e. single pixels), these do not correspond to energy per se but
rather an amount of charge into the FADC. This is better
characterized by the number of FADC counts that correspond to one
pixel firing (see figure). This is independent of attenuation
length. It is does depend on the gain of the sensor and electronics.
However, there are many contributions to the "gain" or conversion
from counts to MeV. For example, the acceptance/transmission of the
light guides contributes to the overall gain factor and this has
nothing to do with the size of the single pixel. Therefore, it might
make more physical sense to simulate the dark hits with minimal
dependence on each channel. If we operate the SiPMs at the same over
bias, this should correspond to the same gain for all sensors.
Therefore, the large variation we are seeing in "gains" may not be
primarily due to the actual sensor gains themselves.<br>
<br>
Hope this gives you sufficient information to think about how to
move forward.<br>
<br>
* What should we use for an energy threshold to write out events? A
4 mV threshold was used before. 4 MeV?<br>
<br>
The threshold should be given in counts, which corresponds to the
DAQ threshold of 105. The pedestal is nominally at 100, so 5 counts
above pedestal. We are using the 2 V scale on the FADCS, which are
12 bits, so one count = 0.0004884 V. Therefore 5 counts is 2.44 mV
assuming the pedestal does not drift. Of course it does, so another
question is whether we wish to include pedestal drifts in the
simulation. Generally one tries to setup hardware, so the software
can ignore such details, but this may not be possible in this case.<br>
<br>
In any case, the thing to do is to convert the energy deposited into
counts, use the pulse shape I have provided (or your own favorite)
to convert this into fADC counts. The threshold would be applied to
this pulse train.<br>
<br>
<br>
* The change to the data structure will be just adding
'incident_id="int"' to 'bcalTruthHit.'<br>
<br>
Others with more expertise should comment on this one.<br>
<br>
** If we don't change the data structure, we'll change bcal_index in
the code and get rid of the incident particle filling.<br>
** I'd prefer changing the data structure, since we'll eventually
want to implement incident particle dependent smearing (I assume),
and it seems relatively easy to do it now.<br>
<br>
* Time smearing: the time resolution in the code for the fADC is
stated as 4 ns / sqrt(12). This was used before because we were
using 0.1 ns bins rather than 4 ns bins.<br>
<br>
This is probably an old guess based on assuming the time coming from
the fADC comes from picking the first FADC sample above some some
threshold. We are doing much better than this by essentially finding
the time at half height. The resolution for this is about 0.2 - 0.3
ns, but Mark can probably provide a better number. I suggest you put
in a value based on Marks latest studies and we can adjust it as
more studies are done.<br>
<br>
** Is this value what we'd want to use for smearing a single truth
time?<br>
<br>
<br>
= Old code =<br>
* We need to decide whether or not we want to keep this method
available for people to choose to use.<br>
* If we do keep it:<br>
** Need to find a value for the energy of one dark hit that causes
waveforms to more closely resemble data and also that gives
reasonable pedestal variation.<br>
<br>
Using the attached scritps used for the pedestal studies, I think we
a first stab at this. See GlueX-doc-2695<br>
<a class="moz-txt-link-freetext" href="http://argus.phys.uregina.ca/cgi-bin/private/DocDB/ShowDocument?docid=2695">http://argus.phys.uregina.ca/cgi-bin/private/DocDB/ShowDocument?docid=2695</a><br>
You can find all the scripts in the tar.gz file. If there is
anything missing, let me know and I can make it available.<br>
<br>
** By fixing an electronic noise smearing, then altering the dark
hit energy, it looks like we want something like the current energy
divided by 10 or so.<br>
** It should be easy to set the dark hit energy based on what
amplitude in mV we want the dark pulses to have, if we have any
feeling for that (1 mV amplitude ~ 1 MeV energy deposition).<br>
<br>
See the notes and GlueX notes above, which should provide good
answers to these questions.<br>
<br>
<br>
<pre class="moz-signature" cols="72">Elton Smith
Jefferson Lab MS 12H3
12000 Jefferson Ave STE 4
Newport News, VA 23606
(757) 269-7625
(757) 269-6331 fax </pre>
<div class="moz-cite-prefix">On 4/30/15 1:12 PM, Zisis Papandreou
wrote:<br>
</div>
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Hi folks:
<div><br>
</div>
<div>the minutes from our short meeting this morning have been
posted:</div>
<div><a moz-do-not-send="true"
href="https://halldweb.jlab.org/wiki/index.php/BCAL_Reconstruction_Meeting_2015-04-30">https://halldweb.jlab.org/wiki/index.php/BCAL_Reconstruction_Meeting_2015-04-30</a></div>
<div><br>
</div>
<div>Please note that since there was a controlled access in the
hall at the same time as the meeting, JLab was not able to join
us. Therefore, we posted Tegan's questions on HDGEANT and
mcsmear on the Wiki (see above minutes). I've placed this
discussion at the top of the agenda of next week's Calorimetry
meeting, as it is important to progress on this and complete the
tasks. Will L. will also join us for next week's meeting.</div>
<div><br>
</div>
<div>We are hoping that after the commissioning ends on Monday,
folks will have a chance to read this list so that we can decide
upon the items and move forward.</div>
<div><br>
</div>
<div>I also posted the minutes from the April 16 meeting: <a
moz-do-not-send="true"
href="https://halldweb.jlab.org/wiki/index.php/BCAL_Reconstruction_Meeting_2015-04-16">https://halldweb.jlab.org/wiki/index.php/BCAL_Reconstruction_Meeting_2015-04-16</a></div>
<div><br>
</div>
<div>Thanks and cheers, Zisis...<br>
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<div><font
class="Apple-style-span"
color="#1d5091"
face="Verdana" size="4"><br
class="Apple-interchange-newline">
Dr. Zisis Papandreou</font></div>
<div style="color: rgb(0, 0,
0);"><span
class="Apple-style-span"
style="font-size: 13px;"><font
class="Apple-style-span"
face="Verdana">Professor
of Physics, Ph.D., P.Phys.</font></span></div>
<div style="color: rgb(0, 0,
0);"><span
class="Apple-style-span"
style="font-size: 13px;"><font
class="Apple-style-span"
face="Verdana">---------------------------------------------------------</font></span></div>
<div style="font-size: 12px;
font-style: normal;
font-weight: normal;"><font
class="Apple-style-span"
color="#929292"
face="Verdana">Department of
Physics </font></div>
<div style="font-size: 12px;
font-style: normal;
font-weight: normal;"><font
class="Apple-style-span"
color="#929292"
face="Verdana">University of
Regina<span
class="Apple-tab-span"
style="white-space: pre;">
</span> </font></div>
<div style="font-size: 12px;
font-style: normal;
font-weight: normal;"><font
class="Apple-style-span"
color="#929292"
face="Verdana">3737 Wascana
Parkway</font></div>
<div style="font-size: 12px;
font-style: normal;
font-weight: normal;"><font
class="Apple-style-span"
color="#929292"
face="Verdana">Regina, SK
S4S 0A2<span
class="Apple-tab-span"
style="white-space: pre;">
</span> CANADA</font></div>
<div style="color: rgb(0, 0, 0);
font-size: 12px; font-style:
normal; font-weight: normal;"><font
class="Apple-style-span"
face="Verdana"><br>
</font></div>
<div style="color: rgb(0, 0,
0);"><font
class="Apple-style-span"
face="Verdana"><b>Phone:
(306) 585-5379</b></font></div>
</div>
</span></div>
</span></div>
</span></div>
</span></div>
</span></div>
</span><span class="Apple-style-span"
style="font-family: Verdana; font-size: 12px;"><font
class="Apple-style-span" color="#929292">Fax: (306)
585-5659</font></span>
<div><span class="Apple-style-span" style="font-family:
Verdana; font-size: 12px;"><font
class="Apple-style-span" color="#929292">Email:</font> </span><a
moz-do-not-send="true"
href="mailto:zisis@uregina.ca">zisis@uregina.ca</a></div>
<div>
<div style="word-wrap: break-word; -webkit-nbsp-mode:
space; -webkit-line-break: after-white-space;"><font
class="Apple-style-span" color="#929292"
face="Verdana">Website:</font> <a
moz-do-not-send="true"
href="http://www.uregina.ca/science/physics/people/faculty-research/zisis-papandreou/index.html"
style="text-align: -webkit-auto;">http://www.uregina.ca/science/physics/people/faculty-research/zisis-papandreou/index.html</a></div>
</div>
</span><br class="Apple-interchange-newline">
</div>
<br class="Apple-interchange-newline">
</div>
<br class="Apple-interchange-newline">
<br class="Apple-interchange-newline">
</div>
<br>
</div>
<br>
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