[Olympus] PRC report
Michael Kohl
kohlm at jlab.org
Wed Feb 5 18:06:36 EST 2014
Dear Jan,
but only the last data points are the ones that matter ... we also
discussed at some point that at high epsilon / low Q2 finding anything but
unity (after radiative corrections) would be very suspicious, and it
could serve as the region where to tune the apparatus.
Anyway, it is good that you provide the "Tempelwache".
Best regards
Michael
On Wed, 5 Feb 2014, Jan C. Bernauer wrote:
> Hi Michael,
>
> I would say: If there is any doubt that maybe we would get a result
> which steers us into saying "Looks good", we have a bias.
>
> The cross section drops by what, a factor of 10000? so 5% should be good
> enough statistics for everything except the last 2 or 3 points.
> So I think there is a real danger there.
>
> Best,
> Jan
>
>
>
> On 2/5/14, 5:33 PM, Michael Kohl wrote:
>> Hi,
>> I did not mean to include the data/MC plot in the report but to look at
>> it myself and for internal discussions.
>> As far as blinding is concerned, this plot would be based on the 100
>> runs representing only some 5% of the data so is this not blind enough
>> for statistical reasons?
>>
>> Best regards
>> Michael
>>
>>
>> On Wed, 5 Feb 2014, Douglas Kenneth Hasell wrote:
>>
>>> Hi,
>>>
>>> I agree with Jan. We must not produce anything yet showing
>>> data/MC. Showing plots of data and MC in a log scale with arbitrary
>>> normalizations are okay but even this is dangerous if the
>>> normalizations are the same for electron and positrons.
>>>
>>> In the future I propose we avoid this problem by actually blinding
>>> the data we release to the collaboration.
>>>
>>> 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
>>>
>>>
>>>
>>> On Feb 5, 2014, at 12:26 PM, Jan C. Bernauer <bernauer at MIT.EDU> wrote:
>>>
>>>> Dear all,
>>>>
>>>> please do NOT do that. We are already dangerously close to produce and
>>>> release a "result". To be honest, even the comparison like it is now is
>>>> too close for comfort for me. The non-MC corrected yield in a log plot
>>>> was the furthest I'm willing to go.
>>>>
>>>> Dividing the measurement by MC gives almost directly the ratio we are
>>>> after - you only have to divide the two numbers in the plot. This most
>>>> certainly can not go in the PRC report. And quite frankly, I'm not sure
>>>> why we even entertained the thought of blinding the data when we go and
>>>> produce results, which will without doubt bias us, the first chance
>>>> we get?
>>>>
>>>> So I'm opposed to producing this plot even for internal use.
>>>>
>>>>
>>>> With best regards,
>>>> Jan
>>>>
>>>>
>>>> On 2/5/14, 9:03 AM, Michael Kohl wrote:
>>>>> Dear Stan, Yury,
>>>>>
>>>>> the logarithmic scale is hiding certain features.
>>>>> Can you produce a plot of the ratios (data/MC) for e+ and e- ? This
>>>>> should
>>>>> take out the leading Q2 dependence and help identify the problem zones.
>>>>>
>>>>> The enhanced e- yield at backward angle was already present in Jan's
>>>>> plot
>>>>> from October.
>>>>>
>>>>> Best regards
>>>>> Michael
>>>>>
>>>>>
>>>>> On Wed, 5 Feb 2014, Belostotski, Stanislav wrote:
>>>>>
>>>>>> Dear Douglas and Jan,
>>>>>> Find please attached two plots (eps and pdf each)
>>>>>> showing comparison experimental yields with MC. The normalization is
>>>>>> done as follows:
>>>>>> Experimental distributions are normalized one to another under
>>>>>> condition
>>>>>> that at Q2 around 1 GeV2 the ratio e+/e- must be equal to 1 ( as I
>>>>>> understand we used the same philosophy as Jan did) ;
>>>>>> The e- MC points are normalized to experiment at Q2=0.65.
>>>>>> I avoid to combine both plots in one (too messy). To be honest,
>>>>>> they are
>>>>>> anyway independent as we have not used normalization to luminosity.
>>>>>> To me the results look good enough. The enhancement around Q2=4 for
>>>>>> positrons has already been well explained by Jan. I am puzzled by
>>>>>> excess
>>>>>> of experiment over MC at Q2 larger 1.5 for electrons (somewhat similar
>>>>>> but much less pronounced for positrons). Is that bgr contamination?
>>>>>> Might be, but it looks rather as a shift by whatever reason.
>>>>>> kind regards Stan,Yuri
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>>>>>> _______________________________________________
>>>>>> Olympus mailing list
>>>>>> Olympus at mit.edu
>>>>>> http://mailman.mit.edu/mailman/listinfo/olympus
>>>>>>
>>>>>
>>>>> +---------------------------------------------------------------------
>>>>> | Dr. Michael Kohl, Associate Professor and Staff Research Scientist
>>>>> | Physics Department, Hampton University, Hampton, VA 23668
>>>>> | Jefferson Lab, C117, 12000 Jefferson Avenue, Newport News, VA 23606
>>>>> | Phone: +1-757-727-5153 (HU), +1-757-269-7343 (Jlab)
>>>>> | Fax: +1-757-728-6910 (HU), +1-757-269-7363 (Jlab)
>>>>> | Email: kohlm at jlab.org
>>>>> | Cell: +1-757-256-5122 (USA)
>>>>> |
>>>>> | Deutsches Elektronen-Synchrotron DESY, Bd. 66, Rm. 6,
>>>>> | Phone: +49-40-8998-6406, Cell: +49-171-101-1967
>>>>> +---------------------------------------------------------------------
>>>>> _______________________________________________
>>>>> Olympus mailing list
>>>>> Olympus at mit.edu
>>>>> http://mailman.mit.edu/mailman/listinfo/olympus
>>>>>
>>>>
>>>>
>>>> --
>>>> Dr. Jan C. Bernauer
>>>> Massachusetts Institute of Technology
>>>> 77 Massachusetts Ave, Room 26-441
>>>> Cambridge, MA, 02139, USA
>>>> Phone: (617) 253-6580
>>>> _______________________________________________
>>>> Olympus mailing list
>>>> Olympus at mit.edu
>>>> http://mailman.mit.edu/mailman/listinfo/olympus
>>>
>>>
>>> _______________________________________________
>>> Olympus mailing list
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>>
>> +---------------------------------------------------------------------
>> | Dr. Michael Kohl, Associate Professor and Staff Research Scientist
>> | Physics Department, Hampton University, Hampton, VA 23668
>> | Jefferson Lab, C117, 12000 Jefferson Avenue, Newport News, VA 23606
>> | Phone: +1-757-727-5153 (HU), +1-757-269-7343 (Jlab)
>> | Fax: +1-757-728-6910 (HU), +1-757-269-7363 (Jlab)
>> | Email: kohlm at jlab.org
>> | Cell: +1-757-256-5122 (USA)
>> |
>> | Deutsches Elektronen-Synchrotron DESY, Bd. 66, Rm. 6,
>> | Phone: +49-40-8998-6406, Cell: +49-171-101-1967
>> +---------------------------------------------------------------------
>>
>
>
> --
> Dr. Jan C. Bernauer
> Massachusetts Institute of Technology
> 77 Massachusetts Ave, Room 26-441
> Cambridge, MA, 02139, USA
> Phone: (617) 253-6580
>
+---------------------------------------------------------------------
| Dr. Michael Kohl, Associate Professor and Staff Research Scientist
| Physics Department, Hampton University, Hampton, VA 23668
| Jefferson Lab, C117, 12000 Jefferson Avenue, Newport News, VA 23606
| Phone: +1-757-727-5153 (HU), +1-757-269-7343 (Jlab)
| Fax: +1-757-728-6910 (HU), +1-757-269-7363 (Jlab)
| Email: kohlm at jlab.org
| Cell: +1-757-256-5122 (USA)
|
| Deutsches Elektronen-Synchrotron DESY, Bd. 66, Rm. 6,
| Phone: +49-40-8998-6406, Cell: +49-171-101-1967
+---------------------------------------------------------------------
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