[Clas12_verystrange] Xi1820 efficiency

[Lei Guo]

I use the following number.

BR for Xi(1820)->Lambda K: 0.3
BR for Lambda--> p pi: 0.64
I assume the vertex efficiency (Lambda-->ppi) is 0.7.

The KKKp channel for Xi(1820) is now 0.6% in the proposal. Still good.

If somebody can clarify whether fastMC included kaon decay, it would  
be great.

Lei
On Apr 6, 2012, at 5:06 PM, Johann Goetz wrote:

> 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.
> 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
>
> _______________________________________________
> Clas12_verystrange mailing list
> Clas12_verystrange at jlab.org
> https://mailman.jlab.org/mailman/listinfo/clas12_verystrange

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