Adjusting Y0 effectively shifts the center of maximum magnetization of your magnet from the center of the slab to the location y' = Y0, where (x',y') = (0,0) is the center of the slab.  The parameter X0 has similar meaning.  These two values are essentially a fine-tuning device and should be changed only after the parameters above have been found.

Step 7.  Compile all FORTRAN programs and use the following LINK command:  LINK DMAIN1, DMAINTESTIN1, FDMOD1, PLOTR4MYY1, PLOTPKG/LIB, SYS$LIBRARY:BELLPORT/LIB, KUTOOLS/LIB, NCAR1/LIB, NCAR2/LIB.

Step 8.  If all has gone right, the program will run until it gives you the following prompt:

'ENTER THE NO. OF LINES PLOTTED FOR Y'

Exit the program for now and examine the file EXTTES.DAT, which lists first the accepted values of the B-field, then the calculated values, then the experimental error, and then the absolute differences between calculated and experimental values.

Step 9.  If you are not satisfied with the results of your calculation, return to Step 6 and continue making changes to FDMOD1.CMN until you are satisfied with your model for the B-field.

Step 10.  Once you think you have a good model, continue with the rest of the program; this part simply plots the results similar to those shown in Section A9.7.  The number of lines plotted for Y will be the number of columns of the original data set.  For the HISCALE instrument, NLN = 11, as can be seen from the data in Section A9.7.  For LNPT and LNK use 1,-1 respectively.  See page 122 in Shodhan's thesis for an explanation.  The number of lines plotted for X will be the number of rows of the original data set.  NLN = 18 for my situation.  After DMAIN1 executes, an IOP020.DAT file is created.  To print the output on the screen or printer, talk to the system manager about the NCTX and NPLOT commands.

A9.12.4  Tracing Out Trajectories

Once the geometry and B-field have been established, you are ready to start adding up trajectories that escape the deflection system.  Start by finding the size and location of your detector and break it up into pieces as was done in Figure A9-8.  Obtain a list of starting coordinates and areas DAi, and keep it close by.

The main trajectory program is TRAJ6PT.  Adjoining programs are CHECHITSEN1, FDMOD1, TDHPCG, TIMER, TRACKSUB5, and TRAJRT2BDET.  The main function of all of these can be found in the documentation in Shodhan's thesis.

If you have COORD.DAT and COEFF.DAT in proper format, and if you have made the appropriate geometry-related changes mentioned earlier, then there are really no major additional changes that have to be made to this list of programs.  Compile and link the above programs.

Upon running the main program, you will be asked a sequence of questions, most of which are fairly self-explanatory.  Here is a step-by-step walk through these prompts:

ENTER THE NAME OF THE FILE OF COORDINATES

Reply:  COORD.DAT

ENTER THE NAME OF THE FILE OF COEFFICIENTS

Reply:  COEFF.DAT

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