[G12] Lambda Total Cross Section update.

[Hicks, Kenneth]

Hi Johann,

It looks like your cross sections are still about a factor of 2 too low, but this is clearly an improvement over previous attempts.

The acceptance looks particularly scattered, probably due to low statistics.  Can you improve this by running more GSIM?

It's a bit tricky to get a correct total cross section without taking small bin sizes in angle and then fitting the angular distribution
to extrapolate into the unmeasured regions of CLAS (such as near the beamline at forward angles).  It's likely that the cross
sections will look better after more work.

Ken

From: g12-bounces at jlab.org [mailto:g12-bounces at jlab.org] On Behalf Of Johann Goetz
Sent: Friday, August 19, 2011 4:29 PM
To: g12
Subject: [G12] Lambda Total Cross Section update.

Hi g12,
I couldn't get this done before the last meeting, but I did a rough total cross section measurement using the most recent gflux data and everything looks pretty good so far. There are a few issues I still need to address, but after certain corrections (the trigger for example) I believe we will have good agreement with older results from CLAS/g1 and SAPHIR.

Here is a link to the plots on the g12 wiki<http://clasweb.jlab.org/rungroups/g12/wiki/index.php/G12_Xi_Paper_-_Lambda_Cross_Sections>

I used 93 complete runs that were evenly distributed throughout g12 - all production runs (no single sector runs).

Please mull this over and get back to me with questions on Monday and I can investigate further before the next meeting.
Have a good weekend everyone!
--
Johann T. Goetz, PhD.
jgoetz at ucla.edu<mailto: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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