[Clas12_verystrange] Xi1820 efficiency

[Johann Goetz]

I think you are right, and I don't know if this was taken into account in
the fastmc. Maybe Mike knows this? Also to answer Lei's question, the BR
for Xi to Lambda/K and the BR for Lambda to p/pi is not taken into account.
I think we can assume 50% for the Xi decay and 64% for the Lambda decay.
This gives us these numbers:

detected particles / % acceptance


BR for Xi and Lambda included:
  K+ K+ K- p / 1.49 %
  K+ K+ K- pi- / 0.96 %
  K+ K+ K- / 5.99 %


BR for Xi and Lambda, and kaon decay included (IF its not in fastmc
already):
  K+ K+ K- p / 0.19 %
  K+ K+ K- pi- / 0.12 %
  K+ K+ K- / 0.75 %


On Fri, Apr 6, 2012 at 2:57 PM, John Price <jprice at csudh.edu> wrote:

> Hi John:
>
> Dumb question: how far does a kaon have to travel in order to be
> detected?  The 5m path length of kaons in CLAS leads to a 50%
> probability that they will decay before hitting the SC.  This would mean
> that we would have a theoretical maximum of 12.5% detection efficiency
> for a K+K+K- final state.
>
> No doubt, the geometry of CLAS12 is different than that of CLAS, but I
> don't know off the top of my head how different it is.
>
> John
>
> On Fri, 2012-04-06 at 11:51 -0700, Johann Goetz wrote:
> > OK, here it is. sorry for the delay in getting this out.
> >
> > I generated 300k of the following reaction:
> >
> > g p --> Xi-(1820) K+ K+
> >   Xi-(1820) --> Lambda K-
> >     Lambda --> p pi-
> >
> > The Xi-(1820) was generated via a massive and broad Y* state with a
> > t-slope of about 1.9 (consistent with g11/g12 results for t-slope of
> > Xi-(1530)). The generator was the Pluto (root-based) library and the
> > efficiency calculator was the fastmc in Mike's home directory.
> >
> > detected particles / % acceptance
> > K+ K+ K- p / 4.66 %
> > K+ K+ K- pi- / 0.30 %
> > K+ K+ K- / 18.73 %
> >
> > --
> > Johann.
> --
> John W. Price
> Professor and Chair of Physics
> CSU Dominguez Hills
> 310-243-3403
>
>


-- 
Johann T. Goetz, PhD. <http://sites.google.com/site/theodoregoetz/>
jgoetz at ucla.edu
Nefkens Group, UCLA Dept. of Physics & Astronomy
Hall-B, Jefferson Lab, Newport News, VA
Office: 757-269-5465 (CEBAF Center F-335)
Mobile: 757-768-9999
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