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<p>Thank you Dipangkar, Thank you Bogdan!<br>
</p>
<p>Ok, with the higher pressure, we compensate the temperature
change. But in light of the larger cross sections, we should think
about reducing the luminosity -- that would help a lot in the
backgrounds, and makes everything just easier to handle.</p>
<p>Best,</p>
<p>Jan<br>
</p>
<div class="moz-cite-prefix">On 8/11/2020 4:12 PM, Dipangkar Dutta
wrote:<br>
</div>
<blockquote type="cite"
cite="mid:CALQ6iZ9oonQ4gw4DajnieMM-pAEav6w3BrJgZ-4WTa56+KFLhg@mail.gmail.com">
<div dir="ltr">
<div>Yes, current plans are to run at room temperature, at 3.5
atm. pressure</div>
<div>Cheers</div>
<div>Dipangkar</div>
<div><br>
</div>
</div>
<br>
<div class="gmail_quote">
<div dir="ltr" class="gmail_attr">On Tue, Aug 11, 2020 at 3:03
PM Jan C. Bernauer <<a
href="mailto:jan.bernauer@stonybrook.edu"
moz-do-not-send="true">jan.bernauer@stonybrook.edu</a>>
wrote:<br>
</div>
<blockquote class="gmail_quote">
<div>
<p>Hi all,</p>
<p>Could somebody quickly confirm that we'll indeed run at
room temp, so with roughly 0.7e36 instead of 3e36 /cm^2/s?</p>
<p>Thanks,</p>
<p>Jan<br>
</p>
<p><br>
</p>
<div>On 8/6/2020 11:43 AM, Jan C. Bernauer wrote:<br>
</div>
<blockquote type="cite">Hi Tim, Hi Wally, Hi TDIS, <br>
<br>
Sorry for the lengthy email. <br>
<br>
Some updates and questions to my talk: <a
href="https://hallaweb.jlab.org/wiki/images/2/2f/TDIS_sim.pdf"
target="_blank" moz-do-not-send="true">https://hallaweb.jlab.org/wiki/images/2/2f/TDIS_sim.pdf</a>
where I found what I believe are internal inconsistencies,
and differences to my own implementation of F_2, f_\pi,
and a full MC. <br>
<br>
Wally, Tim, I also send this to you, because I believe you
might have additional insight to the source of some of
these figures/values. <br>
<br>
<br>
0) Does anybody have the exact bins used for the projected
result figures? Especially the one as a function of t.
That would be very helpful! <br>
<br>
1) I do see about a factor of 2 more inclusive CS than in
the proposal. I think it's likely that this error is on my
end, I have to verify with g4SBS. In any case, the code
version I got from Carlos (Thanks!), authored from Tim and
Wally, do not calculate that as far as I can tell. It's
not helping us in any case, we would just need less
current I'd assume. <br>
<br>
2) It would be great to figure out in which configuration
the code was for the generation of table 6 and 7. I assume
it was this code I attach here? Is that the code version
after a factor 2 has already been found? I believe so,
because I can get the F_2^{\pi p} plots out that are in
the new proposal, which are higher than the old proposal.
<br>
<br>
Some things which I found in the code which do not match
the experiment: <br>
<br>
Theta_e is ~12, not 35 degrees. That only affects the
calculation of Q^2, which is slightly affecting the proton
PDFs. Can't explain a big difference. <br>
<br>
The code was set up for pi^+, I'm looking at pi^0, so I
changed the isospin factor to 1. I changed some other
integration ranges (ymax=1, xmax=0, km1, km2 ), and also
implemented a cosph cut (proton theta<70) <br>
<br>
With these changes, I match exactly (on a log scale :) )
my own implementation and the plots in the new proposal.
<br>
<br>
3) BUT the ratio was still off. I traced it down to
F_2^p. The relevant lines are here: <br>
<br>
CALL SETCTQ6(1) ! CTEQ 'MS-bar' SCHEME. <br>
u_pro = CTQ6PDF (1, REAL(x), SQRT(REAL(Q2))) <br>
ubar_pro = CTQ6PDF (-1, REAL(x), SQRT(REAL(Q2)))
<br>
d_pro = CTQ6PDF (2, REAL(x), SQRT(REAL(Q2))) <br>
dbar_pro = CTQ6PDF (-2, REAL(x), SQRT(REAL(Q2)))
<br>
<br>
F2neu = 2.*x * ((4./9.)*(d_pro + dbar_pro) <br>
& + (1./9.)*(u_pro + ubar_pro)) <br>
<br>
<br>
a) LHAPDF 6 and this code has a different definition for
what PID=1 and 2 are. That stumped me for a while, but I'm
pretty sure u_pro is indeed the proton u PDF. <br>
<br>
b) For the neutron, d_neu=u_pro and vice versa, so the
line actually reads 2 *x * ( 4/9 ( u_neu +ubar_neu) + 2/9
( d_neu +dbar_neu)). I changed it back to be correct for
the proton. <br>
<br>
c) BUT: I do not have the 2 there. Where does that come
from? I'm not super versed in PDFs, but it is my
understanding that that shouldn't be there. If not, can
anybody please explain? <br>
<br>
( d) There is also a small difference in the code here and
LHAPDF for x<0.1. 10% or so. That must be in the
underlying PDF or Q^2 evolution) <br>
<br>
In any case, without the 2, my code and this code
essentially agree on F_2^p (with Q^2=1, very close to the
plots in the proposal. With Q^2 changing, slightly
different from the proposal, maybe 30% at most, but both
codes the same way. Makes me think that the proposal line
comes from a different program, which might explain the
discrepancy with the 2). <br>
<br>
<br>
4) Going back to table 6. We already know that it was not
updated from the first proposal, so it likely already has
a factor of 2 missing in the F/F ratio. With this
additional factor 2, we are getting very close to what my
program has, 4 is close enough to 5 that I would believe
the rest is acceptance, slightly different cuts, etc, or
the first factor 2 was actually 2.5 or something. <br>
<br>
With these changes, both my code as well as the code I got
from Carlos, modified as described above, gives a ratio
F/F of 550 for the first line in the text. This assumes we
accept k between 60 and 500 Mev, x between 0.05 and 0.2,
at around 12 degrees, with 30 to 70 deg proton angle.
This is also the number my MC gets, and roughly what I
would get looking at the plots. Or is there some other
cut that should be applied? Cut on z (y in the code)? <br>
<br>
TLDR: If all my assumptions are correct, we see indeed 5.5
times more TDIS events (per DIS event) than we thought! <br>
<br>
Let me know what you think! <br>
<br>
Best, <br>
<br>
Jan <br>
<br>
<br>
Attached: TDIS_orig.f, code I got from Carlos. TDIS.f:
Code with my modifications. <br>
<br>
<br>
<br>
<br>
<br>
<fieldset></fieldset>
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</blockquote>
<pre cols="72">--
Dr. Jan C. Bernauer
Assistant Professor
Department of Physics and Astronomy
Stony Brook University
Stony Brook, NY 11794-3800 </pre>
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</blockquote>
<pre class="moz-signature" cols="72">--
Dr. Jan C. Bernauer
Assistant Professor
Department of Physics and Astronomy
Stony Brook University
Stony Brook, NY 11794-3800 </pre>
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