<html><head></head><body>Yes, and I did that already.<div><br></div><div>In fact, I modified the decode macro to create a new version that reanalyzes all of our collected data all at once. It's called decodeAll.C.</div><div><br></div><div>Best,</div><div>E.</div><div><br><div><div>On Jun 20, 2013, at 12:37 PM, Carlos Ayerbe-Gayoso <<a href="mailto:gayoso@jlab.org">gayoso@jlab.org</a>> wrote:</div><br class="Apple-interchange-newline"><blockquote type="cite">
<div text="#000000" bgcolor="#FFFFFF">
<div class="moz-cite-prefix">For a small summary, we should run the
decode again for the 12 GeV runs, shouldn't we?<br>
<br>
Carlos<br>
<br>
El 6/20/2013 11:59 AM, Alexandre Camsonne escribió:<br>
</div>
<blockquote cite="mid:CAP0WL2xUNG_JEczfpKbq_a2ZjXpJMy4aaakMu0YXs=Ad8X=DiQ@mail.gmail.com" type="cite">
<div dir="ltr">
<div>yes sorry my decoder was very primitive and I did not take
that into account.<br>
</div>
<div><br>
</div>
<div>Good you figured it out,</div>
<div><br>
</div>
<div>Alexandre</div>
</div>
<div class="gmail_extra"><br>
<br>
<div class="gmail_quote">On Thu, Jun 20, 2013 at 11:33 AM,
Edward Brash <<a href="mailto:edward.brash@cnu.edu">edward.brash@cnu.edu</a>>
wrote:<br>
<blockquote class="gmail_quote">
<div>Hi All,
<div><br>
</div>
<div>OK, I have figured out the ADC overflow issue. It's
a bit complicated, so I am posting this to the gep5
mailing list so that there is a record of it.</div>
<div><br>
</div>
<div>Referring to the CAEN v792 manual (this is the ADC
that we are using), the output buffer actually contains
an overflow bit - it is the 13th bit of the output
buffer. When this bit is zero, then there is a normal
ADC value, and the lowest 12 bits contain the ADC value
... thus 0xFFF in those lowest 12 bits corresponds to
ADC = 4095 in decimal. Now, when the overflow bit is
set to 1 (meaning that there was an overflow in that
channel of the ADC, it turns out that the lowest 12 bits
are NOT just set to 0xFFF, as I would have thought. In
fact, they are encoded with something that looks like
0xFXY, where "XY" is a number which runs from 0 to 255,
and is in fact related to the event number. That is,
these lowest 8 bits start at FF, and then run down to 00
as the event number increases. Once it gets to 00, it
resets to FF and starts over again.</div>
<div><br>
</div>
<div>I attach below a plot of the raw ADC value vs. event
number. For all of the events in this plot, the
overflow bit (bit 13) of the output buffer was 1, so
these really are ADC overflows. The correlation with
event number is obvious. </div>
<div><br>
</div>
<div>So, how to fix this? It does need to be fixed,
because the ADC value for non-overflow events really can
range from 0 to 4096. </div>
<div><br>
</div>
<div>I looked at the code called decodeEel.C, which is the
code that extracts the ADC values from the CODA data,
and I see that indeed, to extract the actual ADC value,
one does a bitwise AND with the mask "0xFFF", as one
might expect would be correct. But, this does not
recognize the overflow bit. So, I changed this to be a
bitwise AND with "0x1FFF", so that when there is an
overflow, it is put near channel 8192 (and the region
just below that), so that now it is clearly separated
from non-overflow events. </div>
<div><br>
</div>
<div>This fixes the problem completely, and now ADC
overflow events are cleanly distinguished from
non-overflow events. </div>
<div><br>
</div>
<div>Best,</div>
<div>E.</div>
<div><br>
</div>
</div>
<br>
<div>
<div><br>
</div>
<div><br>
<div>
<div>On Jun 20, 2013, at 9:29 AM, Mark Jones wrote:</div>
<br>
<blockquote type="cite">
<div>Carlos,<br>
As Charles says you are right. Maybe it is
the "summing" module which saturates.<br>
<br>
Mark<br>
<br>
----- Original Message -----<br>
From: "Carlos Ayerbe-Gayoso" <<a href="mailto:gayoso@jlab.org">gayoso@jlab.org</a>><br>
To: "Edward Brash" <<a href="mailto:brash99w@gmail.com">brash99w@gmail.com</a>><br>
Cc: "Mark Jones" <<a href="mailto:jones@jlab.org">jones@jlab.org</a>>,
"Edward Brash" <<a href="mailto:edward.brash@cnu.edu">edward.brash@cnu.edu</a>>,
"Edward Brash" <"Edward Brash"@<a href="http://smail.jlab.org/">smail.jlab.org</a>>,
"Ed Brash" <<a href="mailto:brash@jlab.org">brash@jlab.org</a>>,
"Vina Punjabi" <<a href="mailto:punjabi@jlab.org">punjabi@jlab.org</a>>,
"Charles F. Perdrisat" <<a href="mailto:perdrisa@jlab.org">perdrisa@jlab.org</a>><br>
Sent: Wednesday, June 19, 2013 5:53:41 PM<br>
Subject: Re: 12 GeV data<br>
<br>
I'll check it, but I have some questions of this
point of view, maybe <br>
I'm losing something of what we had from SLAC or
could be some lack of <br>
knowledge from me.<br>
<br>
I understand that every peak we have in the sum of
energies histogram <br>
represents a certain number of electrons delivered
by the accelerator <br>
(5-6 electrons in the 3 GeV, 3 electrons in the 12
GeV). When we said <br>
that the machine provides electrons of 3, 9 or 12
GeV, we assume that <br>
every electron of the bunch has an energy of this
number (3, 9, 12 GeV) <br>
with certain sigma but bigger, is this correct?<br>
<br>
Then, I assume that every electron contributes to
the shower <br>
independently, so, the sum or the contribution of
every shower is what <br>
the calorimeter measures. If I understand
correctly, Mark, you said that <br>
with 36 GeV part of the shower goes out of the
calorimeter, but I think <br>
this is true if we have electrons of 36 GeV and
this is not the case, <br>
isn't it?<br>
<br>
Please correct me if I'm wrong or I misunderstand
something... sometimes <br>
I assume things that seems logic to me and they're
not.<br>
<br>
Best<br>
<br>
Carlos<br>
<br>
El 6/19/2013 5:10 PM, Edward Brash escribió:<br>
<blockquote type="cite">Good point ... :)<br>
</blockquote>
<blockquote type="cite"><br>
</blockquote>
<blockquote type="cite">Dr. Edward J. Brash<br>
</blockquote>
<blockquote type="cite">Department of Physics,
Computer Science & Engineering<br>
</blockquote>
<blockquote type="cite">Christopher Newport
University<br>
</blockquote>
<blockquote type="cite">work: <a href="tel:%28757%29%20594-7451">(757) 594-7451</a><br>
</blockquote>
<blockquote type="cite">cell: <a href="tel:%28757%29%20753-2831">(757) 753-2831</a><br>
</blockquote>
<blockquote type="cite"><a href="http://www.cnu.edu/pcs">www.cnu.edu/pcs</a><br>
</blockquote>
<blockquote type="cite"><br>
</blockquote>
<blockquote type="cite">On Jun 19, 2013, at 4:48
PM, Mark Jones <<a href="mailto:jones@jlab.org">jones@jlab.org</a>>
wrote:<br>
</blockquote>
<blockquote type="cite">
<br>
</blockquote>
<blockquote type="cite">
<blockquote type="cite">I realized that for the
SLAC 12 GeV data run the 3rd peak that should
be at 36 GeV has<br>
</blockquote>
</blockquote>
<blockquote type="cite">
<blockquote type="cite">
less energy because it is lost through the
back of the calo. But it would<br>
</blockquote>
</blockquote>
<blockquote type="cite">
<blockquote type="cite">interesting to confirm
with GEANT.<br>
</blockquote>
</blockquote>
<blockquote type="cite">
<blockquote type="cite"><br>
</blockquote>
</blockquote>
<blockquote type="cite">
<blockquote type="cite"><br>
</blockquote>
</blockquote>
<blockquote type="cite">
<blockquote type="cite"><br>
</blockquote>
</blockquote>
<blockquote type="cite">
<blockquote type="cite">
Cheers,<br>
</blockquote>
</blockquote>
<blockquote type="cite">
<blockquote type="cite">
Mark<br>
</blockquote>
</blockquote>
<blockquote type="cite">
<blockquote type="cite">
<br>
</blockquote>
</blockquote>
<blockquote type="cite">
<blockquote type="cite"><br>
</blockquote>
</blockquote>
<br>
</div>
</blockquote>
</div>
<br>
<div>
<div>
<div><p class="MsoNormal"><i>Dr. Edward J. Brash</i></p><p class="MsoNormal">Department of Physics,
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</blockquote>
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</blockquote>
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