[Clas12_verystrange] Cascade mass splitting

[Michael Dugger]

Hi,

I have some plots of the Cascade mass splitting.

For the Xi-, I plotted the missing mass distribution for gamma p -> K+ K+ 
X. For the Xi0, I plotted the missing mass distribution for gamma p -> K+ 
K0_short X.

Each mass distribution was fit with a voigtian distribution. I could not 
get a reasonable fit using just a Gaussian.

>From the fit, the masses were found to be:
mass(Xi-) = 1321.30 +/- 0.03 MeV
mass(Xi0) = 1315.04 +/- 0.08 MeV

This would give us a mass resolution better than 100 keV and that sounds 
unreasonable to me.

One of the reasons that the mass distribution is too good is that I do 
not have the forward tagger in the fastmc code that I use. Neglecting the 
tagger resolution issue, we can say that the uncertainty in the mass 
measurement will most likely be dominated by systematics errors that I 
have not estimated.

Even if we did have the tagger resolution in the simulations, it would 
probably just make the peak a bit wider and not shift the center too much 
(just a guess).

The plots can be found at
eps format -> 
http://www.jlab.org/Hall-B/secure/clas12/omegaMinus/ASU/CascadeSplit.gif

gif format ->
http://www.jlab.org/Hall-B/secure/clas12/omegaMinus/ASU/CascadeSplit.gif

Take care,
Michael