A Polarimeter for Low Energy X-ray Astrophysical Sources
(PLEXAS)
Poster
Poster (gzipped) presented at the HEAD2000
meeting. There
are two figures missing: the exploded
view and the
laboratory measurement that
verifies the testing facility. Here is
a better version of the photo in the poster, which shows the SAO
summer intern, Emily M. Laubacher working on the experimental
apparatus. Here is another picture of
the setup.
Features of the instrument:
- Can be used to measure X-ray polarization in 3 bandpasses
centered at 0.23 keV, 0.25 keV and 0.27 keV
- Polarizations are measurable to +/- 1-3 % in a day for most targets
- Multilayer coatings give the optics good reflectivity (up to 30%
in the s polarization) at 45 degree angles of incidence
- Compact design (1 m by 0.3 m) suitable to the NASA UNEX program
- Detectors time events to 1-10 microsec, so that pulsars can be observed
Examples of targets:
- BL Lac Objects with relativistic, magnetized jets which
should be polarized up to 60 %
- Isolated pulsars such as PSR 0656+14, which have a strong magnetic
field which will polarize the surface emission at the 20-50% level
- Quasars and Active Galactic Nuclei (AGN) whose disks will show
polarized emission due to electron scattering up to 12%
Updated: January 4, 2001