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Session 121 - Instrumentation: Status and Plans.
Oral session, Thursday, January 18
La Condesa, Hilton

[121.04] Calibration of a HEXTE Phoswich Detector at the National Synchrotron Light Source

L. Wayne, W. Heindl, R. Rothschild (UCSD)

We present here results of calibrations of a flight spare phoswich detector from the High Energy X-ray Timing Experiment (HEXTE). HEXTE is one of the primary instruments on NASA's X-ray Timing Explorer, which is scheduled for launch during late 1995. These calibrations were carried out with an X-ray beam at the Brookhaven National Synchrotron Light Source. The beam used provides monochromatic (few eV FWHM) X-rays in the nominal energy range 7-60 keV. Such a tunable, monochromatic beam is ideal for understanding detector response, as laboratory radioactive sources offer only relatively few discrete energies and have spectra distorted by such effects as scattering internal to the source itself.

We examine several detector properties, in particular the non-linear light output of NaI(Tl) as a function of photon energy (with special attention to the region around the discontinuity at the Iodine K-edge). K-escape fractions as a function of energy are measured and compared with theory. Energy resolution and the shape of peaks produced by monoenergetic X-rays are examined.

These data provide us with important properties of the detector response and will be used to optimize the in-flight HEXTE instrument response matrix.

Program listing for Thursday