[Clas12_verystrange] Xi1820 efficiency

[Michael Dugger]

Lei,

I do not think that the fastmc does any decays, but could be wrong about 
this. Derek probably knows the answer.

-Michael

On Fri, 6 Apr 2012, Lei Guo wrote:

> 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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