foc_vs_dens

NAME

foc_vs_dens - determine the relationship between the focus of a shell (as estimated by trace-shell) and the photon density of the incoming ray bundle.

PARAMETERS

foc_vs_dens uses the standard parameter interface

out_tag filename
The tag parameter gives the name of the rdb files in which the foc_vs_dens results will be written. (Actually, the filenames will be out_tag_res and out_tag_res2, the second file being a summary of the first). The rdb _res file will contain the determined focus for each trace-shell run which foc_vs_dens performs, and the _res2 file will contain the average focal value and rms about that value for each photon density.

numrand integer
This parameter specifies how many random iterations of trace-shell should be run for each photon density.

shell integer
This is a parameter which is sent directly to trace-shell3, and determines what mirror shell the generated rays will be reflected against.

energy real
This is another ``trace-shell3'' parameter, and gives the energy of each photon (in keV)

bundle_az real
This parameter specifies the desired off-axis azimuthal angle (in arcmin) of the ray bundle and is used by trace-shell3.

bundle_el real
This parameter specifies the desired off-axis elevation angle (in arcmin) of the ray bundle and is used by trace-shell3.

tally boolean
if set to yes, the photons passing through trace-shell will be tallied to the screen every tallycnt counts.

tallycnt integer
If tally has been set to yes, then this parameter determines after how many counts the running total will be displayed on the screen.

config_db string
This parameter tells trace-shell which mirror configuration database file to use. The config_dir parameter to trace-shell is assumed to always be /proj/axaf/simul/databases/ts_config. All of the mirror configuration database files are presumed to be located in this directory.

version boolean
If set to yes, simply print the version and die.

debug string
This parameter gives the user the option of setting various debug flags. As of now, there are no particular debug options in foc_vs_dens.

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DESCRIPTION

foc_vs_dens is a module which allows the user to run the trace-shell procedure multiple times with randomized initial seeds, and over a range of photon densities. The goal of foc_vs_dens is to provide the relationship (in tabular form) between the accuracy of the trace-shell estimated focus, and the density of the incoming rays. The list of densities is already hardwired in. All the user has to do is specify the number of trace-shell iterations per photon density, the name of the output file tag, and nine basic parameters which are to be used by trace-shell on every run. The required input format is a phot/dpde ray stream; output is sent to two different rdb files, which will be discussed below. Note that, although no parameters in trace-shell3 need to be set directly, it is necessary that the trace-shell3.par file be accessible (in addition to the foc_vs_dens.par file) in order for foc_vs_dens to be able to successfully invoke trace-shell3.

One of the output rdb file databases which foc_vs_dens generates contains the focus (as determined by trace-shell and getfocus) for each of the trace-shell3 runs. (This rdb file is denoted by a _res extension.) It also contains the shell, energy, and photdens input parameters to trace-shell3, as well as the particular run number for whatever the current density is. The second rdb file is a summary of this first database, and contains the average and rms z-value for the focus, for each of the photon densities in the study.

The user does have the option of altering the list of photon densities in the study, however it is impossible to do so through any other means but actually altering the source code. The random value ranges for the seed1, seed2, and block parameters are hardwired in as well, at 1 billion for each seed, and 1 million for the block parameter. One other built-in parameter is the configuration database for trace-shell3, which is set to /proj/axaf/simul/databases/ts_config. The actual file, of course, can be specified by the user. It is expected that any file that the user could possibly wish to use must be in the aforementioned database.

A couple more notes should be made concerning the execution of foc_vs_dens. First of all, although trace-shell3 is the only ``module'' that it calls, foc_vs_dens also depends heavily on a little routine called get_focus, which reads the focus from a .focus.lis file that is written by trace-shell during each run-through. Secondly, as both databases are rdb files, standard rdb routines are employed in updating them. This means that before a entry is added to either database, the input parameters characterizing the entry are checked against the database to see if any duplicate entry exists. If so, then this entry is removed. In any case, the new entry is entered into the database.

AUTHOR

C.C. Carpenter