The major changes in version 4.02 include the addition of many more fields in the FTM output bank.
Several values are filched from the monte-carlo if the MC banks are present when FTM is run. This allows such items as the stopping position of the muon to be compared to the fit.
The impact parameter of the muon is found to be highly subject to
fitter pull. An analytic expression is used to move the impact
parameter from 
to 
, which is corrected systematically
for fitter pull. This is stored in the KFTM_pcorr word. Note that
this correction is a function only of , not of any other
parameter, and is based on MC assessments of the muon fitter.
The most important change in version 4.02 is the inclusion of an assortment of goodness-of-fit parameters that can be used to determine if the fit hypothesis is good. It is NOT recommended that the chi-squared parameter be used for this.
Two values in particular are important:
KFTM_FShould: This parameter indicates the fraction of tubes in the
track forward Cherenkov cone that fired. That is, a value of 0.95
means that 95% of all the tubes that SHOULD have fired due to direct
Cherenkov light did in fact fire. Good fits should have an FShould
parameter of greater than 0.8. Bad fits will have values less than 0.5.
KFTM_pdf_dof: This parameter is a summed log-likehoold of time
residuals for all the tubes in the event, dividied by the number of
tubes. The pdf function used to create the log-likelihood is a
piecewise continuous function created using the time residuals from MC
muons. Larger values of the parameter indicate worse fits. Good fits
typically have pdf_dof values less than 4.5. Exteremely bad
fits will have values of about 6.5.
For more information on the operation of the Muon Fitter, refer to Nathaniel Tagg's Ph.D. thesis.