[Halld-physics] Physics Working Group Meeting: Tuesday, October 16 @ 11:15 am

Tue Oct 23 09:36:20 EDT 2018

Cool. Then, please adjust this plan accordingly.  I can provide CLAS g1c
ds/dO as I did for
g12.  Please let me know

Cheers, igor

-----
Igor Strakovsky, SAID INS The George Washington University
Tel: 571-553-8344(VC),202-994-4742(FB),Skype: igors1945_2,
Cell: 703-728-5627,Emails: igor at gwu.edu, igor at jlab.org

On Tue, Oct 23, 2018 at 9:27 AM Justin Stevens <jrsteven at jlab.org> wrote:

> The minimum Eg is 25% of the endpoint energy, which is fixed by the tagger
> field and TAGH counter geometry.  So the minimum Eg for these runs would be
> ~2.9 GeV.
> -Justin
>
> On Oct 23, 2018, at 9:22 AM, Igor Strakovsky <igor at gwu.edu> wrote:
>
> Hi Justin,
>
> Plan looks great.  I have two small comments
>
> - The min Eg is still unclear.  So, if one can possible to go a little bit
> below 3 GeV then CLAS
> g1c data for pi0 is reachable [DUGGER, PRC76, 025211(2007)]: Eg
> = 2875, 2825, 2775 and so on
>
> - I would not use  previous measuremen
> <https://halldweb.jlab.org/DocDB/0008/000809/002/GlueX_doc_809.pdf>as the
> source to compare with because most of data
> came from brem Bonn measurements which systematics is out the control.
>
> Cheers, igor
>
> -----
> Igor Strakovsky, SAID INS The George Washington University
> Tel: 571-553-8344(VC),202-994-4742(FB),Skype: igors1945_2,
> Cell: 703-728-5627,Emails: igor at gwu.edu, igor at jlab.org
>
>
> On Tue, Oct 23, 2018 at 7:54 AM Justin Stevens <jrsteven at jlab.org> wrote:
>
>> Hi Igor, All,
>>
>> Yes, as we discussed at the Physics WG meeting last week, there are 2
>> possibilities for low energy measurements which correspond to your bullets
>> below.  The priority was given to proposing a run plan for this Fall, since
>> time is limited.  Thanks to Sean for collecting the relevant data and rate
>> estimates for this Fall’s proposal at
>> https://halldweb.jlab.org/wiki-private/index.php/2018_Low_energy_measurements.
>> The short summary is that we would like to propose a ~5 day run with a
>> lower PS field setting to give statistical errors <10% on cross sections
>> for comparison to previous measurements, and this is on the agenda for
>> today’s bi-weekly meeting.
>>
>> This Fall’s proposal of course does not preclude running in Summer 2019,
>> but would give us some data in the short term to compare with previously
>> measured cross sections.  To make a decision on Summer 2019 running, we
>> would need a similar proposal with the stated goals, rate estimates, and
>> required running time.
>>
>> -Justin
>>
>> On Oct 17, 2018, at 4:34 PM, Igor Strakovsky <igor at gwu.edu> wrote:
>>
>> Hi Justin,
>>
>> According to my understanding there are two different run periods
>>
>> - this fall which will allow to cover 4-9 GeV or so.  CLAS6 does not have
>> pol measurements
>>
>> - next summer which is a low energy run which you spelled out. that is
>> different story
>>
>> Cheers, igor
>>
>>
>> On Wed, Oct 17, 2018 at 1:15 PM Justin Stevens <jrsteven at jlab.org> wrote:
>>
>>> Hi Igor,
>>>
>>> Thanks for your feedback.  My understanding is the accelerator would run
>>> at half energy (Ee ~ 5.5 GeV), and as usual we could choose to set the
>>> coherent peak as we prefer.  The hodoscope in this case would cover Eg ~
>>> 1.5 GeV to the endpoint, although it will still be only half instrumented
>>> (sampling) between 1.5 and 3.5 GeV.  So data below Eg = 4 GeV could be
>>> possible in this scenario, but at a lower efficiency.
>>>
>>> -Justin
>>>
>>> On Oct 15, 2018, at 3:11 PM, Igor Strakovsky <igor at gwu.edu> wrote:
>>>
>>> Hi Justin,
>>>
>>> It would be good to spell out a possible Eg range and our goals for
>>> summer of 2019.  Then all depends.
>>>
>>> I reported twice that if our range is limited by 4 - 6 GeV and our main
>>> goal is diff cross sections then
>>> g12 from CLAS6 will work for us.  There are no CLAS pol measurements in
>>> this case.  So, we have
>>> gp-->pi0p cross sections published several month ago and Volker's
>>> analyses for gp-->etap and
>>> gp-->omegap are under the HW group review now.
>>>
>>> If one can possible to go below 3 GeV then we will have more options
>>> including polarized
>>> measurements. Additional benefit will come from the ability to use the
>>> PWA technology to evaluate
>>> new data and possibility to provide "good" event generators for MC.  See
>>> my slides at DB
>>>
>>> Cheers, igor
>>>
>>>
>>>
>>> -----
>>> Igor Strakovsky, SAID INS The George Washington University
>>> Tel: 571-553-8344(VC),202-994-4742(FB),Skype: igors1945_2,
>>> Cell: 703-728-5627,Emails: igor at gwu.edu, igor at jlab.org
>>>
>>>
>>> On Mon, Oct 15, 2018 at 12:50 PM Justin Stevens <jrsteven at jlab.org>
>>> wrote:
>>>
>>>> Hi All,
>>>>
>>>> There’s been a proposal to have a short discussion about a potential
>>>> low-energy run in Summer 2019 during tomorrow’s physics meeting.  To frame
>>>> the discussion: the accelerator plans to run at ~half energy during
>>>> June/July 2018 and GlueX could potentially run parasitically during this
>>>> period.
>>>>
>>>> We had some discussion about the potential usefulness of low-energy
>>>> running earlier this year (comparison to cross section measurements from
>>>> CLAS, energy-dependence of polarization observables, etc.), but that was in
>>>> a different context of using the full energy electron beam with lower
>>>> coherent peak settings (see
>>>> https://halldweb.jlab.org/wiki-private/index.php/Aug_7,_2018,_Physics_Working_Group
>>>> ).
>>>>
>>>> If you have something you would like to contribute to the discussion,
>>>> please let me know.
>>>>
>>>> -Justin
>>>>
>>>> On Oct 14, 2018, at 1:46 PM, Justin Stevens <jrsteven at jlab.org> wrote:
>>>>
>>>> Hi All,
>>>>
>>>> Our next Physics WG meeting we be Tuesday, October 16 at 11:15 am,
>>>> https://halldweb.jlab.org/wiki-private/index.php/Oct_16,_2018,_Physics_Working_Group.
>>>> Please let me know if you have something you would like to present.
>>>>
>>>> -Justin
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>>>>
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>>>
>>>
>>>
>>
>
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