HESSI SCIENCE AND SIMULATIONS

This is an old listing of different web pages with HESSI or
HESSI-related science topics and simulations. For the HESSI home page at GSFC,
go to
http://hesperia.gsfc.nasa.gov/hessi/. For the UCB HESSI home
page, go to
http://sprg.ssl.berkeley.edu/hessi/.
For the HESSI European
Data Center, go to
http://www.hedc.ethz.ch/.
SIMULATIONS:
- HESSI
Effective area calculations.
New effective area calculations including the effects of shutters.
Richard Schwartz, 21-Apr-1998.
-
Preliminary Outline of the HESSI end-to-end test. The main
purpose or the HESSI End-to-End Test (also called the "Imager
Modulation Test" or the "gridlet test") is to show that the HESSI
collimators, as mounted on the telescope tube, will modulate
X-rays. At each stage of HESSI development, the test should be done
under conditions and configurations as close as possible to those of
flight. Ed Schmahl, Jan-1998.
- Imaging
Spectroscopy. Simulations of the imaging capability of HESSI
at different photon energies using the known parameters of its
collimators and standard methods of RMC image reconstruction. Ed
Schmahl, Jun-1997.
- Reconstruction
of Point- and Extended Sources using Maximum Entropy
Methods. These images show the effects of using only 2 or 4
HESSI collimators on mapping combined small and large sources. The
motivation for this is to illustrate the tradeoffs required at high
energies where only two grids will be thick enough to modulate
photons. Ed Schmahl, 19-Dec-1997.
- The
effect of varying grid thicknesses on HESSI photon
transmission. Calculations of the high-energy photon
transmission using different grid thicknesses, compared to the
thicknesses used in the HESSI-SMEX proposal. Jim McTiernan,
21-Nov-1997.
-
HESSI MEM test images using different grid models. Simulated
HESSI images, for the 500 keV continuum and the 2.223 MeV line. All
are generated using the Maximum Entropy Method (MEM). Jim McTiernan,
14-dec-1997.
- HESSI
Sensitivity calculations using the newest grid thicknesses.
The newest grid thicknesses and the resultant foldout figures for the
PhaseA proposal. Richard Schwartz, 27-dec-1997.
- Molybdenum
as a possible HESSI window material. Almost any material
with the Z of aluminum, or greater, would do to a first approximation
as an entry window for HESSI hard X-ray imaging. This is because the
photoeffect dominates the total absorption cross-section out to 30 keV
or higher, so that all of the unwanted solar thermal emission can be
suppressed sharply. However, this said, which material? This note
offers Mo (Z=42) as an alternative. Hugh Hudson, 6-Jan-1998.
RELATED DATA:
- Examples
of HEIDI SAS Data. Plots of SAS data from
the HEIDI Balloon Flight, June 22, 1993. Ed Schmahl, 23-Dec-1997.
- Yohkoh
HXA data. HXA is the aspect system for the HXT instrument on
Yohkoh, the Yohkoh analog of the HESSI SAS. Hugh Hudson, 22-dec-1997.
- More
Yohkoh HXA data. A recent set of HXA scans obtained from
Yohkoh. The X and Y coordinates are tilted at 45 degrees from solar
NS. The notches in the scans are due to shadows of fiducial grids
mounted on the rear grid plane of the HXT telescope itself. The
locations of the limbs and of the fiducial marks are determined in
hardware on board Yohkoh by a simple threshold identification. Also
includes the IDL code that generated the figures. Hugh Hudson,
18-Feb-1998.
SCIENCE ISSUES:
-
Notes on Reconstruction Software. Important issues about
simulation and image reconstruction software that should be discussed
by the interested parties on the HESSI team. Ed Schmahl, Dec-1997.
DOCUMENTATION:
- HESSI
Documentation. A current list of the files and directories
in the /hessidoc directory, on hesperia.gsfc.nasa.gov.
Back to Top?
Updated, 6-Jan-1998, J.McTiernan
Comments to: jimm@ssl.berkeley.edu