[Clas12_calcom] DC calibration challenge

[Mac Mestayer]

Hello Raffaella and Dan;

Our group has made considerable progress on developing a
calibration suite for the chambers.

For a while, we have had a complete (if untested) functional
form which describes how the drift time depends upon the track's
distance from the wire, the local angle of the track and the local
value of the B-field.  We also built a ROOT-Minuit fitter which
fit time as a function of DOCA which has been operational for
many months.

Now, we are making two major changes:
1- putting the fitting under a JAVA-based graphical interface, and
2- introducing a realistic distance to time function into GEMC.

We are aiming to achieve the CALCOM group's goal of producing
GEMC data with a distance to time function using a blinded set
of parameters; reconstructing with our initial set of parameters,
and running the calib. gui to determine a better set of
parameters, and iterating until we get back to something close
to what was put into GEMC.

I propose that we proceed with the following steps:

1) generate GEMC tracks at a few selected kinematics: 6 GeV/c electrons
at 20 deg.; 3 GeV/c pi+'s at 15 deg. with distance to time digitization
done with nominal parameters; followed by reconstruction with
nominal parameters and running the calib. gui.

2) Once we can do step 1 with some reliability, we can try the same
tracks but with GEMC digitization with slightly distorted parameters
and repeat the steps.

NOTE: steps 1 and 2 do not require any hit selection criteria since
all tracks are the same (except for random smearing).

3) Once this converges, we try using a Pythia-generated set of
tracks.  We then work on developing criteria for the data-selection
cuts, and then do the fitting, re-cooking, etc.

4) Finally, we can use Pythia events with a blinded set of input
distance to time parameters.

Comments? ... or suggestions?        - Mac


"mestayer at jlab.org", (757)-269-7252