The SIM Subsystem of COMPASS
The SIM Subsystem of COMPASS
This page contains information regarding the SIM subsystem of COMPASS. This software is
used to generate simulated events in the COMPTEL experiment and to generate both spatial
and spectral response information.
SIM Task Descriptions
- SIMGAM - COMPTEL Photon Simulation
Most recent version - 21.
This task performs the basic event simulation for a specified input spectrum and instrument
configuration. The output from this job is a sequence of raw simulated event messages
(datatype QEV). Each raw event contains the precise value of each event parameter. These
data do not represent simulated COMPTEL events in that they do not incorporate the
effects of limited resolutions, spatial information, etc., that are inherent in the real
experiment.
Software Users Manual |
COMPASS Software Profile |
Version History
- SIMFIN - Final Processing of Simulated Event Data
Most recent version - 14.
This task processes each event in the QEV file generated by SIMGAM. The processing
involves the broadening of the various event parameters to provide a more realistic
simulation of all event parameters. The output can either be in the form of
processed event data (EVP) or in the form of processed burst data (PBS). SIMFIN
is also capable of generating a shortened form of the EVP data (SEV) that also
retains the input photon energy data.
Software Users Manual |
COMPASS Software Profile |
Version History
- SIMPSF - Simulated PSF Generation
Most recent version - 12.
This task uses simulated EVP data to generate instrumental point spread functions (PSFs)
that correspond to the response of the COMPTEL telescope mode. Both 2-dimensional (IAQ)
and 3-dimensional (FAQ) forms of the PSF are generated. The input spectrum corresponding
to the PSF is the same as that specified in the corresponding SIMGAM job.
Software Users Manual |
COMPASS Software Profile |
Version History
- SIMSPG - Synthesized PSF Generation
Most recent version - 3.
This task performs generates point spread functions (PSFs) for a user-specified
input spectrum by synthesis from a series of monoenergetic PSFs (as generated
from SIMPSF).
Software Users Manual |
COMPASS Software Profile |
Version History
- SIMRSP - Simulated Response Matrix Generation
Most recent version - 3.
This task generates a spectral response matrix using input SEV data as generated by
SIMFIN.
Software Users Manual |
COMPASS Software Profile |
Version History
SIM Dataset Descriptions
- IDT - Instrument Definition Table
Required Input To : SIMGAM
An encoded physical mass model of the COMPTEL instrument, a required
input dataset to SIMGAM. The IDT dataset is sometimes referred to as the
"COMPTEL mass model" (not to be confused with the "GRO mass model" that
describes the mass distribution of the entire GRO spacecraft).
- ISP - Input Spectrum Table
Optional Input To : SIMGAM
Represents an optional means of specifying an input source spectrum
to the SIMGAM task. An ISP dataset is simply a text table of histogram values,
listed by input energy interval, by which any arbotrary spectral shape can be
defined for the sampling of beam photon energies.
- QEV - raw simulated events
Standard Output From : SIMGAM
Required Input To : SIMFIN
The QEV dataset contains the raw simulated event messages. The event
parameters in this case correspond to the 'true' values with no
instrumental resolution broadening.
- ISS - Instrument Status Table
Required Input To : SIMFIN
Contains information on the various instrumental response characteristics,
such as detector thresholds, spectral resolution parameters, spatial
resolution parameters, timing resolution parameters, module status, and
burst mode definitions. These data are used to statistically "broaden"
each event to more accurately reflect the true response of COMPTEL. This
is required input to SIMFIN.
- EVP - (simulated) processed event messages
- PBS - (simulated) processed burst data
- SEV - Shortened EVP data (with input energy value)
- FAQ - 3d point spread function
- IAQ - 2d point spread function
- BRM - Burst Response Matrix
- ERG - Energy Response Matrix (telescpe data)
SIM Data Production
Event Simulations (QEV, EVP)
Generating QEV data is the most CPU-intensive part of the SIM process.
Here we have collected data that have been generated by the team.
The following links provide access to reports generated by a perl-based
script run at UNH. (The dataset status, therefore, reflects the status
at UNH.) Note that QEV data generated by SIMGAM versions 15 or earlier
was generated without tracking of secondary particles. All UNH QEV
datasets generated with SIMGAM version 15 or earlier have therefore
been assigned quality flag values of -100; these data should be
considered as an inaccurate representation of the COMPTEL response.
The following reports are specifically for datasets generated by
SIMGAM version 16 and later. Note that quality flag assignments
are not available for a large fraction of these data.
- Telescope Simulations with Wide Parallel Incident Beam (IBEAM = 11, IDIVER = 0)
- Telescope Calibration Simulations with Wide Incident Beam (IBEAM = 11, IDIVER = 1)
- Burst Simulations (IBEAM = 2)
- D1 Background Simulations (IBEAM = 6)
- 40K Background Event Simulations (IBEAM = 12)
- 24Na Background Event Simulations (IBEAM = 10)
- 28Al Background Event Simulations (IBEAM = 13)
- 27Mg Background Event Simulations (IBEAM = 14)
- 22Na Background Event Simulations (IBEAM = 15)
- 55Co Background Event Simulations (IBEAM = 16)
- 56Co Background Event Simulations (IBEAM = 17)
- Diffuse Emission Simulations (IBEAM = 9)
Directly Simulated PSFs
In the direct simulation approach, the user provides the input spectrum
directly to one or more SIMGAM jobs. This is followed by one or more SIMFIN jobs (one
corresponding to each SIMGAM job). Once the SIMFIN jobs are completed, the complete set
of resulting EVP data is used as input to SIMPSF to generate a single IAQ/FAQ pair
that represents the instrument response.
So the PSF generation is done using the SIMGAM/SIMFIN/SIMPSF tasks within COMPASS.
- E-2 power-law spectrum, 10° zenith angle
- E-2 power-law spectrum, 20° zenith angle
- E-2 power-law spectrum, 30° zenith angle
- Wien spectrum, kT = 300 keV, 15° zenith angle
Synthesized PSFs
These PSFs were generated indirectly using a library of individual PSFs. The individual PSFs
were generated with the SIMGAM/SIMFIN/SIMPSF route. The synthesized PSFs were then generated
using SIMSPG.
SIM Documentation
COMPASS Documents
COM-RP-UNH-SIM-056 : issue 1 : September 23, 1997
PSF Library Simulations : 10 deg zenith angle, wide incident beam
COM-RP-UNH-SIM-054 : issue 2 : January 19, 1998
PSF Library Simulations : 30 deg zenith angle, wide incident beam
COM-RP-UNH-SIM-055 : issue 1 : June 5, 1997
PSF Library Simulations : 40 deg zenith angle, wide incident beam
COM-RP-UNH-SIM-049 : issue 1 : May 13, 1996
D1 Sensitivity as a Function of Zenith Angle
Author: R. M. Kippen
COM-RP-UNH-SIM-048 : issue 1 : May 9, 1996
Effect of Secondary Particles on the Telescope Response
Author: R. M. Kippen
COM-RP-UNH-SIM-047 : issue 2 : April 25, 1996
Revised COMPTEL SIM Mass Model Description
Author: R. M. Kippen
COM-RP-UNH-SIM-046 : issue 1 : March 25, 1996
Effect of Secondary Particles on the PSF
Author: R. M. Kippen
COM-TN-UNH-SIM-044 : issue 1 : February 17, 1995
Event Requirements for Simulated PSFs
Author: M. McConnell
COM-RP-UNH-SIM-041 : issue 1 : October 26, 1994
Point-Spread_function Synthesis Using a High Statistics PSF Library
Author: R.S. Miller
COM-RP-UNH-SIM-039 : issue 1 : June 22, 1994
Description of the COMPTEL SIM Mass Model (IDT Dataset)
Author: J.G. Stacy
COM-RP-UNH-SIM-021 : issue 3 : July 14, 1994
Log of Available IDT/ISS/ISP Datasets for SIM Processing
Author: J.G. Stacy
COMPTEL Team Meeting Handouts / Viewgraphs
The team meeting presentations have contained a great deal of information regarding the
development of the SIM subsystem and the generation of COMPTEL point spread functions
(PSFs). Viewgraphs from some of the more recent presentations are available below.
Team Meeting, MPE (Garching), April 15-17, 1998 :
Viewgraphs (pdf)
Team Meeting, SRON (Utrecht), October 14-16, 1997 :
Viewgraphs (pdf)
Team Meeting, UNH (Durham), March 4-7, 1997 :
Viewgraphs (pdf)
Team Meeting, SSD (Noordwijk), November 19-22, 1996 :
Viewgraphs (pdf)
Team Meeting, MPE (Garching), July 23-26, 1996 :
Viewgraphs
Team Meeting, SSD (Noordwijk), April 4-7, 1995 :
Viewgraphs
Last Updated: May 19, 1998
Dr. Mark L. McConnell
Space Science Center
Morse Hall, Rm 312
University of New Hampshire
39 College Road
Durham, NH 03824-3525
Phone: (603) 862-2047
Fax: (603) 862-4685
E-mail:
Mark.McConnell@unh.edu