[Olympus] remaining program

[Norair Akopov]

Dear All,

I also agree that the present knowledge for a beam energy uncertainties, 
which is on the level of 1.6*10^-4 (in worse case 3.5*10^-4) is still
much better than the limit Stan has mentioned (if we accept this 
estimation):
"beam instability of 1 MeV  may result in 0.28% false asymmetry at
scatt. angles >40 deg.",
1MeV is 5*10^-4, then we should expect at mentioned angle essentially 
less than 0.2% false asymmetry. I would say this could not 
be an essential source of our systematics.

As to the plan to perform additional studies with also the negative 
polarity, I do not think we can realize something conclusive from such 
short studies with the lumi decreased by factor 10.
I also prefere to continue with the regular data taking, then we can have 
opportunities to put more hard cuts (e.g. specific fiducial cuts) to clean 
the data.


Best regards,
Norik

On Thu, 20 Dec 2012, Douglas 
Kenneth Hasell wrote:

> Hi,
>
> 	I would vote to NOT have another energy calibration run.  It is unfortunate that the last measurement was unsuccessful but looking at the existing monitoring of the energy with Uwe I am reasonably confident that the variations are on the order of 10^-4 or at least can be corrected for to this level.
>
> Cheers,
> Douglas
>
> On Dec 20, 2012, at 4:43 PM, Brinker, Frank wrote:
>
>> Dear all,
>> Beside the program you discuss here I want to ask whether another energy
>> calibration is wanted.
>> We have a calibration for e+ and e- from mid of November  and for e+
>> from Dec 22nd.
>> A try for e- in December was not successful.
>>
>> I can offer to try another calibration in the night from Dec 31st to Jan
>> 1st.
>>
>> Best regards
>> Frank Brinker
>>
>>> -----Original Message-----
>>> From: olympus-bounces at mit.edu [mailto:olympus-bounces at mit.edu] On
>>> Behalf Of Michael Kohl
>>> Sent: Thursday, December 20, 2012 2:14 PM
>>> To: olympus at mit.edu
>>> Subject: [Olympus] remaining program
>>>
>>> Dear all,
>>>
>>> we have collected 3.2 fb^-1 so far, almost close to the design
>>> luminosity.
>>>
>>> For the 12-day addendum we should make a plan for a set of additional
>>> measurements that could be helpful for the analysis.
>>>
>>> Here is my proposal for low-luminosity running:
>>> -run all four configs (e+-,B+-) without shielding but with the
>> intensity
>>> reduced to optimze the noise, each for a day.
>>> E.g. reduce lumi by x10, expect ~3Hz elastics = 250k elastic events per
>>> day -> 20 mA current / 0.2 sccm flow;
>>> vary the magnetic field (100%, 75%, 50%, 25%) every six hours.
>>> Open up the trigger by reducing the prescale on the 3-of-4 trigger type
>>> to max out the DAQ (<30-40% deadtime).
>>>
>>> This would cost us four days of running.
>>> A data set with minimized noise can help us train and optimize the
>>> reconstruction software, rather than using "noisy" high-luminosity
>> data.
>>>
>>> A dataset with minimized moise in all four configs will show how the
>>> cancelations in the ratio occur and will help us validate the MC.
>> Varying
>>> the magnetic field in addition will serve the same purpose. The
>> statistics
>>> will be good enough for the validation at forward angles, where also
>> the
>>> systematic effects on the single-polarity ratio were the largest.
>>> In the end we will need to be able to trust the MC for B+ at low
>> epsilon.
>>>
>>> At low luminosity, a trigger which is more more open also allows to
>> verify
>>> TOF and trigger efficiencies, and to break any inefficiencies further
>> down
>>> as a function of channels, coordinates etc.
>>>
>>> We should start producing that set of measurements beginning on
>> Saturday,
>>> so that it could be finished by Wednesday. If it takes longer we still
>>> have a few days left. Any final remaining days would be used to further
>>> improve the statistics.
>>> Frank Brinker also would like to do another Touchek energy measurement,
>>> probably on Dec 31 / Jan 1.
>>>
>>> If you have further ideas or wishes, please bring them up.
>>>
>>> Best regards
>>>  Michael
>>>
>>>
>>>
>>> +---------------------------------------------------------------------
>>> | Dr. Michael Kohl, Assistant 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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>>
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>
>
>                                                    Cheers,
>                                                            Douglas
>
> 26-415 M.I.T.                                 Tel: +1 (617) 258-7199
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>
>
>
>
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