[Frost] A couple of things

[Eugene Pasyuk]

There is no technical reason for that. Coherent edge can be moved to 
anywhere we like it to be.

Volker Crede wrote, On 06/14/10 06:47:
> Eugene,
>
> yes, I am certainly interested in gn->(p)npi+pi- and would like to analyze
> it. In the past, we always had the coherent edge at 1.1 GeV, 1.3 GeV, etc.
> instead of 1.0 GeV, 1.2 GeV, etc. Was there any technical reason for this?
>
> I fully agree with the choice for the beam energy and the suggestion for a
> two-sector trigger.
>
> Best wishes
>
>      Volker
>
>
> On Sun, 13 Jun 2010, Eugene Pasyuk wrote:
>
>> Hi all,
>>
>> There are couple of things on our hands to take care of.
>>
>> The first one is Run coordination for the next two months between June
>> 19 and August 13. That's 8 weeks. So far I have not heard voices of
>> volunteers except Patrick. I hope you don't expect two of us to cover
>> these 8 weeks, or do you?
>>
>> The second is related to the potential three week extension and
>> possibility to run with deuteron target. Volker needs written
>> justification 1-2 pages with brief description of what and why we are
>> going to do during this extra time. We also should say who is going to
>> analyze these data.
>> We started this discussion awhile ago. It looks like we reached a
>> consensus about what we are going to do. Let me summarize.
>> We will run with linearly polarized beam on transversely polarized
>> deuteron target. Since the time is limited we can run only one coherent
>> edge setting. We can concentrate on the kinematical range around W=1.7
>> GeV. I think it reasonable to set coherent edge probably at 1.2 GeV.
>> Earlier Igor compiled and sent out some data to support this particular
>> energy. We need to summarize to something half a page to a page of text.
>> To run with coh_edge at 1.2 the best would be to go with 3 pass beam.
>> That would be 3.36 GeV electron beam. If we go 4 pass, the end of the
>> tagging range will be about 0.89 GeV a bit to close to 1.2 GeV.
>>
>> We can go after three reactions.
>> gn->pppi-
>> gn->npi+pi-
>> gn->K0Lambda
>>
>> There are no doubts about feasibility of the first two. The cross
>> section is large.
>> For the third one we need to get some estimates, what we can expect in
>> terms of statistics and uncertainties. Franz, you did it for HDIce.
>> Could you quickly recalculate it for FROST.
>> A few other things to consider for experiment configuration.
>> Since all of those reaction requires at least two charged particles to
>> be detected we may go with two sector trigger.
>> For the 2pi reaction we would need to detect recoil neutron. It makes
>> sense to turn on LAC to have better acceptance for neutrons.
>> There is also question of torus field polarity. Do we want to run
>> reversed polarity (positive inbending) like g13 did or keep it as it is now?
>>
>> We still don't know what material we will have. Two options are being
>> considered. d-butanol or d-propandiole. All depends on the availability
>> of proper radical.
>> d-butanol is preferable in terms of dilution factor. The figure of merit
>> butanol vs. propandiole is roughly 1.2.
>> As far as the degree of polarization is concerned with both materials
>> people were able to get 80% polarization.
>> Even though we are talking about three week extension realistically we
>> may expect that we will probably have two weeks for data taking (one
>> week for conversion and set up of the target.
>>
>> Manpower for analysis. The list is open. There are some ideas
>> Mike Dugger (ASU) expressed interest to analyze pppi-.
>> I would imagine Volker and Steffen would be interested to analyze 2pi?
>> KLamda - Franz?
>> Please, comment on this.
>>
>> We have to prepare this justification within two weeks.
>>
>> -Eugene
>>
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