[Olympus] PRL paper
Belostotski, Stanislav
stanislav.belostotski at desy.de
Mon Nov 7 07:59:58 EST 2016
Dear Michael,
Many thanks for explanations.
Yet, the MIE method, probably correct, will make a reader puzzled.
The thesis is good but hard to find for reading.
So a few lines of explanations are still needed.
Also my other comments (e.g. beam position/slope uncertainties) are not
answered.
What is really missing is a written "data release report" with all
details of the data analysis. This is a standard request in a
collaboration before the results go for publication. The internal
criticism is much too much better then external one.
I am terribly sorry but can anybody explain why we are so much in a
hurry to publish our FIRST results.
With best regards Stan
On 07.11.2016 15:12, Michael Kohl wrote:
> Dear Stan,
>
> let me try to chip in a few remarks which are hopefully helpful.
>
>
> On 1./ regarding pion production:
> Background rates are asymmetric w.r.t. pi+/pi-, however each pion is
> almost symmetric w.r.t. e+/e- (ignoring TPE).
> Pion backgrounds would have to be either of type where a pion (pi0) is
> produced in addition to ep but not detected (highly but not totally
> suppressed by missing mass analysis), or by misidentification of pi+ as
> e+, or pi- as e-. These are suppressed even more because there would be
> no proton in coincidence.
> If at all, we are dominated by the former which is mostly e+/e-
> charge-symmetric. In reality the nature of observed residual backgrounds
> is more random-like, from the particle flux from upstream to downstream.
> Residual background was identified and subtracted, but not modeled in MC.
> The size of residual background is now mentioned.
>
> On 2.:
> The MIE method is described in detail in Axel's thesis, and as far as I
> can tell, it correctly takes the intensity dependence of the coinc ee&ep
> (prop L^2) over single ee (prop. L) into account.
>
> On 3.:
> Many crosschecks were done with the MC, including e.g. generating and
> propagating an e+p sample but analyzing it as e-p and vice versa, and by
> switching the toroid back and forth for the MC samples.
> The generator was extensively tested and validated against ESEPP.
>
> Best regards
> Michael
>
>
>
> On Mon, 7 Nov 2016, Belostotski, Stanislav wrote:
>
>> Dear Douglas and all,
>> I am surprised not to find ANY reaction to my comments sent 04.11.2016,
>> neither in the paper text nor at least by a mail. To remind, the
>> comments are attached below. Regards StanB
>> P.S. Sorry, I will not participate the meeting today
>> ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,
>> 1.Table 1.
>> A couple of items :
>> -uncertainty due to beam positions and slopes is missing ;
>> -"geometry". What does geometry mean? Is that alignment imperfection?
>> "Elastic (event) selection and bgr subtraction".
>> There is no discussion in text about background which at large angles
>> is mostly related to pion production. Remember, the latter is charge
>> asymmetrical. I can assume that the pion contribution is small but at
>> least a few lines on pion production is needed.
>> 2.Page 3, left, paragraph "The integrated luminosity...."
>> These MIE , as stated in this paragraph, are coincidences of small angle
>> ep scattering and Moller or BhaBha coincidence events.So they are random
>> coincidences(?). Then they must be corrected for the beam intensity
>> variations(?). Or this is my ignorance (?).Ref.29 does not help ( "to be
>> published"). Why just small angle ep scattering is not usable for
>> normalization?
>> I presume similar questions will be put by a referee.
>> 3. It is well known that kinematic constrains used for event selection
>> effect strongly on RC contribution. Extraction of net TPE effect from
>> the ratio is only possible if these constrains are strictly identical
>> for e+ and e-. On the other hand the e+/e- acceptances are different.In
>> a bin in Q**2 this is of course solved applying eq.1. The question is
>> still how much false asymmetry can be resulted from imperfections of MC
>> simulation. Was the MC model tuned somehow and cross-checked?
>> I think we need a few lines on that point.
>> 4.page4 with Fig.2.correct misprint at line 4. left (simulation)
>> 5. My opinion on ranking in the author list is in details in my previous
>> mails.
>> ..............................................................
>>
>>
>>
>> On 07.11.2016 2:09, Douglas K Hasell wrote:
>>> Dear Colleagues,
>>>
>>> Attached is what is I hope the final version of the PRL paper.
>>>
>>> Just a reminder: the collaboration meeting is tomorrow, Monday,
>>> November 7, at 10:00 EST (16:00 CET).
>>>
>>> Cheers,
>>> Douglas
>>>
>>> 26-415 M.I.T. Tel: +1 (617) 258-7199
>>> 77 Massachusetts Avenue Fax: +1 (617) 258-5440
>>> Cambridge, MA 02139, USA E-mail: hasell at mit.edu
>>>
>>>
>>>
>>>
>>>
>>>
>>>
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