[Olympus] remaining program
Belostotski, Stanislav
stanislav.belostotski at desy.de
Thu Dec 20 12:48:18 EST 2012
Dear Norik and all,
Please go to OLYMPUS WIKI
https://olympus-docu.hiskp.uni-bonn.de/dokuwiki/doku.php?id=readinessplots
The numbers I have given are absolutely correct.
They are reproduced by Jan one to one. So please do not be mis leaded by
otherwise.
As for energy variation, I of course did not have in mind absolute
energy calibration, only would like to experimentally measure the
sensitivity to 1 MeV variation of the beam energy, yes , for one beam
species would be enough. Otherwise, only MC correction could be applied
which is to me somewhat risky. I would like to remind that Novosibirsk
people are very much concerned about the beam variation monitoring. So
if to increase the energy by some 10 MeV is not a big deal and not time
consuming I would proceed with that.
Merry Christmas, StanB
On 20.12.2012 18:12, Norair Akopov wrote:
>
> 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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>>
>>
>>
>> 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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