Title: 

High-Accuracy Calibration of the HXDS Flow-Proportional Counter for AXAF at the PTB laboratory at BESSY 

Authors:
Auerhammer, Jutta M.; Brandt, G.; Scholze, Frank; Thornagel, R.; Ulm, Gerhard; Wargelin, Bradford J.; McDermott, Walter C.; Norton, Timothy J.; Evans, Ian N.; Kellogg, Edwin M.

Affiliation:
AA (Physikalisch-Technische Bundesanstalt) AF (Smithsonian Astrophysical Observatory) 

Journal:
Proc. SPIE Vol. 3444, p. 19-29, X-Ray Optics, Instruments, and Missions, Richard B. Hoover; Arthur B. Walker; Eds. (SPIE Homepage)

Publication Date:
11/1998

Origin:
SPIE

Abstract Copyright:
(c) 1998 SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Bibliographic Code:
1998SPIE.3444...19A

Abstract

The Smithsonian Astrophysical Observatory uses the HRMA X- ray Detection System (HXDS) to  calibrate the High-Resolution Mirror Assembly of the Advanced X-ray Astrophysics Facility AXAF.  Apart from two high-purity-germanium solid-state detectors (SSDs) with good energy resolution and  very high efficiency at higher energies, the detection system comprises seven flow proportional counters (FPCs) and one microchannel-plate High-Speed Imager. For the lower energy range, the FPCs are  more appropriate. They have been calibrated at the radiometry laboratory of the Physikalisch- Technische Bundesandstalt, using the electron storage ring BESSY. For the determination of the  absolute quantum efficiency two methods have been applied. First, the detector response was  measured in the lower energy range 0.1 keV to 1.7 keV at several discrete energies using  monochromatized radiation. The absolute photon flux has been determined by Si n-on-p photodiodes,  calibrated against a cryogenic electrical-substitution radiometer used as primary detector source  standard BESSY, which can be calculated very accurately. Combining both measurements the  determination of the detection efficiency over the entire desired spectral range was possible with a  typical relative uncertainty around 1 percent to 2 percent in the central energy range.