XRCF Phase 1 Efficiency Analysis

back to HETG at XRCF

(Final analysis, 7/24/1999)

Plots of grating 1st order efficiency: measuremented, modelled, and residual values.
Analysis of the XRCF Phase 1 Effective Area / Efficiency data suggests that
the 'N0003 sub-assembly models are accurate to ~ 10% in 0th and 1st orders.
(Click above to download .ps files; Efficiency table below also includes 0th order and .gif plots.)

Results and References

The plots above and in the tables below show the results of analysis of the XRCF Phase 1 EIPS grating effective area and efficiency measurements; hence the prefix "eae_" in the filenames. The measured efficiencies are the ratio of grating-in to grating-out measurements corrected for the effects of a non-monochromatic source.

A summary listing of the data sets analyzed including links to the simultions which produced the "feature fraction" corrections is available:

Summary listing of the file eae_wfracs.rdb. MARX simulation plots are linked from the aperture field. The "Effic." column is the measured efficiency; the "Fractions" column gives the "feature-fraction" corrections to grating-in and grating-out measurements that were applied.

The final results of the analysis are available in the rdb files:

The final results table of the eae analysis in rdb format.
feature fractions companion file to eae.rdb

For a detailed description of the data and analysis methods see: Section 7.4 of the HETG Ground Calibration Report or the July, 1998 SPIE paper (2.4 Mb .ps)

A detailed discussion of the Feature-Fraction Corrections is available:

Plots from the Analysis

The following plots were made from the final results file eae_wfracs.rdb by the IDL procedures eae_plots.pro and eae_plot_resids.pro, see below for more details.

Overview and Data Format

In order to analyze and compile the range of Effective Area / Efficiency data and results from XRCF grating measurements, a data table format was devised (and may be modified or extended.) This table is in rdb format. The xrcf_data.fmt file, below, describes the various columns in some detail. Goals of this data table process include i) that it have sufficient information to allow automated retrieval of data files, ii) values can be traced and sanity checked, iii) sufficient ancillary information is available to make various informative plots.

All operations are performed through IDL routines to minimize manual operations (though a lot of manual "knowledge" is included/encoded in the routines and key files) and to allow the analysis to be redone automatically. [See eae_do_it_all.pro, below.]

Processing Steps and Products

The IDL procedures used for the processing are described below in the order that they are applied. Here the steps are summarized with example output.

Effective area measurements (except monochromator scans) of 1st and 0 orders (and related no-grating measurements) were selected from the req_run cmdb by eae_fill_from_cmdb.pro.

The selected CMDB lines were then used to create an eae rdb file. This file has only the columns filled in that can be determined from the CMDB (trw_id, grating, etc.) and it has one line per TRW ID. By using eae_fill_runids.pro the date code, runids, etc. were added to the eae file "eae_wids.rdb".

The file eae_wids.rdb has enough information in it to allow the retreival and analysis of the MST data for selected lines by the routine eae_pha_anal.pro. At this point multiple iterations are detected and the output file, eae_wcounts.rdb, will now have a line per iteration.

Currently counts-in-the-bump are extracted using simple ROI analysis performed using the raw .pha data files by eae_pha_anal.pro. Note that the ROI to use is spelled out for all detectors in the routine eae_roi.pro.

The counts could also be supplied at this point from XSPEC analysis results, if available. Also, eae_pha_anal will be modified to use gaussian fitting with a modelled continuum.

After the multiple iterations have been "expanded", the procdure eae_fill_order.pro can be run to assign the diffraction order to the runid/iteration. With the counts available, they can be turned into fluxes and effective areas by eae_flux_anal.pro. This routine makes use of eae_bnd_hrma_area.pro to get the various BND effective-at-HRMA areas. This routine also has logic for what to ratio to use for the effective area: currently choosing to ratio FPC_X2 to FPC_HN if available (FPC_5 if not) and ratioing SSD_X to SSD_5 if available (then FPC_HN, FPC_5 if not).

Finally, for grating analysis, the ratio of grating in to grating out can be formed. The routine eae_fill_refs.pro reads a manually created data file that specifies what TRW_IDs should be used as reference (grating-out) measurements for which grating-in TRW_IDs. Then the relevant reference values are calculated/copied by eae_update_ref_vals.pro. Finally the actual efficiency is calculated as the ratio of the measured effective area value to the reference value by eae_effic_anal; setting /FRACTION and supplying a "feature_fractions" structure (from feature_fractions.rdb) will have the feature-fraction corrections applied. See the feature-fractions discussion for more information.

The final result is the eae table eae_wfracs.rdb (available at SAO in /home/dd/data/eae/ and at MIT in /nfs/spectra/d6/eae/ .)

Software Used for "eae_" Processing

The eae s/w is primarily in ~dd/idl/xrcf/ at MIT and SAO, with exceptions as noted. The details of the feature-fraction correction s/w are given on the Feature-Fraction Corrections page, creating the "feature_fractions.rdb" file used by eae_effic_anal.pro.

The prime output product is the eae_wfracs.rdb file. Summaries of this file and plots of its data are made using:

Creates a test listing of useful columns etc. to the screen/file.
How to make fun plots from all the data in the eae table.
Creates efficiency plots along with residuals.

The work-horse routines are listed below in roughly the order in which they are used on the data:

This procedure is most useful as a compilation of the steps taken to go from and cmdb and ancillary data files to eae output values in an rdb data table. The various routines called here are described in the rest of this list.
This procedure reads the cmdb and outputs an eae table with columns filled in based on the cmdb.
This fills in the MST date and run ids for the measurements by using a runid lookup rdb table (eae_trw_mod.rdb). At this point the eae table has one line for each run id (even if many iterations.)
This is the fun one: reads lines from the eae table, gets the raw data, performs simple ROI counting, and generates plots. The counts, time, etc. are stored in the eae table and the table grows to have a line per iteration.
Returns ROI regions given an input run id - here's one place for lots of human work to be stored! These ROI values can also be used to generate input for gaussian fitting in future...
The grating order is assigned by this routine based on the CMDB.
With raw counts for the detectors available, this routine calculates the source flux at the HRMA and the effective area of the measurement (using eae_bnd_hrma_area.pro). If the SSD or a CCD is the focal plane detector then the SSD_5 flux is used, otherwise the FPC_HN, and if not the FPC_5 flux.
This routine returns the effective geometrc area of a detector referenced to the HRMA aperture - used to correct for BND apertures and distances.
This procedure assigns no-grating reference measurement ids to the grating measurement lines by reading the file ref_meas.rdb .
This procedure fills in the relevant reference effective area value from the reference measurement. The reference_id can have the forms:
trw_id                 use single TRW ID as reference
trw_id*factor          use TRW ID with a correction factor
trw_id+trw_id          add two or more reference IDs
trw_id+trw_id*factor   add two or more ref IDs and apply a correction factor
blahblah = value       use the value given here as the reference
in order to take into account the differences in shutters between the with and without grating measurements. Special cases are also be coded here.
This procedure calculates the grating efficiency by ratioing the grating/no_grating measurements. The statistical errors reported are those of the with-grating case only. When feature-fraction corrections are not applied, the systematic errors indicate the likely range of error due to these and other effects. When feature-fraction corrections are applied, the systematic errors are given by the combination of the feature-fraction errors for both the grating and no-grating measurements.
Procedure to make/copy the latest eae stuff to the web directory.

Useful routines used:

Key input data files:
These files are located at MIT in ~dd/idl/cmdb/Phase2/ and at SAO in ~dd/data/ .
Other data files:

This page is http://space.mit.edu/HETG/eae/eae.html

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