[Frost] A couple of things

[Volker Crede]

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
>