We give an overview of track fitting using the Kalman filter
method in the NOMAD detector at
     CERN, and emphasize how the wealth of by-product information can
be used to analyze track
     breakpoints (discontinuities in track parameters caused by
scattering, decay, etc.). After reviewing
     how this information has been previously exploited by others, we
describe extensions which add
     power to breakpoint detection and characterization. We show how
complete fits to the entire track,
     with breakpoint parameters added, can be easily obtained from the
information from unbroken fits.
     Tests inspired by the Fisher F-test can then be used to judge
breakpoints. Signed quantities (such as
     change in momentum at the breakpoint) can supplement unsigned
quantities such as the various
     chisquares. We illustrate the method with electrons from real
data, and with Monte Carlo simulations
     of pion decays. 

the article mentioned above is attached in .ps format.


-- 
Nate Rodning, Associate Chairman
Professor of Physics
University of Alberta
(780) 492-3518      Fax:  492-0714
http://www.thehungersite.com/

Filename: Kalman-NOMAD.ps

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