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Re: more on mass resolutions in GlueX/HallD relative to E852



Hall D PID Mail List:

On Sat, 15 Mar 2008, Prof Paul Eugenio wrote:

Dear Paul,

very nice results, but I have a couple of questions to the simulations.
what are you using on the resolutions for the gammas and threshold
detecting gammas in the FCal and BCal. I guess you have seen the nice
report by Matt and Mihajlo
http://www.jlab.org/Hall-D/guest_secure/Calo_Review_Feb08/Pre-Brief%20Materials/simulation.pdf
They did a lot of studies on neutrals like the eta and pi0.

Actually did you find some time to look in the report?

cheers elke

> Date: Sat, 15 Mar 2008 16:13:55 -0400
> From: Prof Paul Eugenio <eugenio@fsu.edu>
> To: halld-pid@jlab.org, GlueX Tracking <halld-tracking-hw@jlab.org>,
>      GlueX Software <HallD-Offline@jlab.org>
> Subject: more on mass resolutions in GlueX/HallD relative to E852
>
> Hi,
>
> I have estimated the resolutions of narrow resonances and compared these
> results to known vales from E852.  Two well measured E852 narrow states
> are the omega and the etaprime.  The omega signal observed in the
> reaction pi- p -> n pi+ pi- 2 piz was fitted to a Gaussian with a sigma
> of 19 MeV (see image e852-4pi-omega.jpg).  The etaprime was observed in
> pi p -> n eta pi+ pi-. A Gaussian fit to the etaprime resulted in a
> sigma of 10 MeV (see image e852-etapipi-etaprime.jpg).  In both E852
> analyses a kinematic fit was performed constraining the eta and pizero
> masses, and constraining the missing four-momentum mass to the neutron.
>
> At present we have not finalized on the eta & pizero reconstruction
> along with a fully constrained kinematic fit.  Because of this, the
> GlueX response was esitmated by approximating the final reconstructed &
> kinematically constrained etas and pizeros with the generated eta and
> pizero momenta.
>
> Both etaprime and omega events were generated with the standard e^-5|t|
> distribution.  Both angular distributions were generated isotropic. For
> the charged particles, the fiducial acceptance and smearing described
> earlier were used.  Eta and pizero acceptance were ignored.
>
> The etaprime was generated with a 1 MeV BW width.  After smearing, the
> etaprime signal was fitted to a Gaussian with a sigma of 7.6 MeV (E852
> measured 10 MeV).   See figure in file smeared-etaprime.pdf.
>
> The omega was generated according to the PDG BW width of 8 MeV.  After
> smearing, the convoluted width was fitted to just a Gaussian resulting
> in a sigma of 15 MeV (E852 measured 19 MeV).
>
> Paul
>
>
> --
> --
> Prof. Paul Eugenio
> Department of Physics
> Florida State University
> Tallahassee, FL  USA
>
> 850-644-2585
> eugenio@fsu.edu
>

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