calibrate dE/dx

1. fits.C reads the 7 parameters from a dedx.cal file for each case (rapidity, centrality, particle type). The file should include 7 lines, with m1 on line 1, m2 on line 2,$\cdots$ , m7 on line7. The script reads this file to calculate the centroids of dE/dx Gaussians.

2. edit lsf file, here let's assume it's called fits/py0h1/pi/fits.lsf (positive pions, y = 0, keyword = h1). Here you can change parameter a0 to 1 or 0. Set it to 1 if you want to run the calibration.

Near the end of the file, you can see the script calling root4star to execute dedxcal.C. Make sure it's not commented out.

3. when you are ready to run, do

source fits/py0h1/pi/fits.lsf

4. when finished, a new dedx.cal file will be created. The old file will be renamed dedx.calold. Some gif files of Bethe-Bloch curves may also be created.

5. look at the dE/dx Gaussians. If the fits are poor, allow more movement in centroids and maybe widths. Then rerun the fitting script. If they look good, keep narrowing the movements. Rerun the script. Do it until you can fix all the centroids.