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<div class="moz-cite-prefix">Hi Maxime, <br>
<br>
I can understand that if we keep working with binned data sets
that changing the energy can create such issues. However, is this
the way we want to continue, instead of moving towards non-binned
data analysis, which I think will not have these same issues and
allows more flexibility in the final physics analysis? We should
explore this possibility more. <br>
<br>
Volker<br>
<br>
<br>
<br>
On 10/26/18 12:03 PM, mdefurne wrote:<br>
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<p>Dear Volker,</p>
<p>I completely agree with F-X about the recommendation of keeping
the beam energy as stable as possible. And I agree that
combining this two "data set" might significantly increase the
systematics. This kind of exercise is extremely complicated and
the final results tends to be extremely sensitive to the overall
systematics. (You can trust me on this for having done it in
Hall A and it was with a much simpler experimental setup.)</p>
<p> Kind regards,</p>
<p>Maxime<br>
</p>
<div class="moz-cite-prefix">On 25/10/2018 19:37, Francois-Xavier
Girod wrote:<br>
</div>
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cite="mid:CAOKxh47rq+O8jw_kwW0Vzmumuz0f3HZEeGoGvm_eNyNWYy6UHg@mail.gmail.com">
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<div dir="ltr">Dear Volker
<div><br>
</div>
<div>The DVCS group has some experience combining datasets at
6.75 and 6.88 GeV. It does actually require caution and
should be evaluated carefully before stating that we can
accept such differences of 100 MeV or more. The issue is not
simply that the cross-section changes, which can affect the
real part of the amplitude, but the issue is also that the
kinematics change. Q2 is not the same in xB and theta bins.
Of course we can attempt to correct for this by changing the
binning in theta to keep Q2 fixed, but then we also change
xB... And in the end, even if we somehow manage to keep xB
and Q2 both fixed, we will still have a change in epsilon
which enters the Rosenbluth separation when combining beam
enegies. </div>
<div><br>
</div>
<div>In writing our proposal we do not have strong constraints
on the absolute beam energy, but we do have an expectation
that the energy will be fixed at better than the MeV level.
Combining beam energies as far as 100 MeV will for certain
affect our systematical uncertainties. If we really have to
work with this, then we must do our homework and put a
number on this. I do not think it is a straightforward
exercise however.</div>
<div><br>
</div>
<div>Best regards</div>
<div>FX</div>
</div>
<br>
<div class="gmail_quote">
<div dir="ltr">On Thu, Oct 25, 2018 at 1:15 PM burkert <<a
href="mailto:burkert@jlab.org" moz-do-not-send="true">burkert@jlab.org</a>>
wrote:<br>
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<div class="m_3725191116230764221moz-cite-prefix">All,<br>
<br>
I agree with intention of the text. However, I suggest
to downplay the 6.5 vs 6.4 GeV. I don't think it is such
a big deal and we have to deal with that later again as
the machine energy will never be exactly the same as in
previous run periods. We have to learn how to deal with
slight energy variations in an effective way. <br>
<br>
Typo: In the next to last paragraph please delete the
first "during" in the string " <span> during as soon as
possible during the November RG..</span> <br>
<br>
Regards,<br>
Volker<br>
<br>
<br>
On 10/25/18 7:41 AM, Annalisa D'Angelo wrote:<br>
</div>
<blockquote type="cite">Dear All, <br>
<br>
after last RGK meeting, some additional thinking and
exchange of information with Raffaella, I have put
together a draft letter to answer the CCC request
information, which you may find at: <br>
<br>
<a class="m_3725191116230764221moz-txt-link-freetext"
href="https://userweb.jlab.org/%7Eannalisa/hybrid_baryons/RGK_response_to_CCC.docx"
target="_blank" moz-do-not-send="true">https://userweb.jlab.org/~annalisa/hybrid_baryons/RGK_response_to_CCC.docx</a>
<br>
<br>
In a nut shell I would like to propose that the new
trigger requiring a central hadron could be implemented
and commissioned as soon as possible during RGA, not to
loose time during our assigned RGK data taking. RGA
could take all the Spring data taking in return. <br>
<br>
This would optimize the overall efficiency. <br>
<br>
Please let me know your opinion on the matter. <br>
<br>
Any comment/correction/suggestion is highly appreciated
<br>
<br>
All the best <br>
<br>
Annalisa <br>
<br>
p.s. we may discuss the matter tomorrow at the RGK
weekly meeting. <br>
<br>
<br>
</blockquote>
<p><br>
</p>
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