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Instrument: HESSI SPECTROMETER
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Associated Platforms
RHESSI

Spectral/Frequency Information
Wavelength Keyword: X-Ray
Number Channels: 1

Related Data Sets
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Description
The Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI) spectrometer
contains nine germanium detectors that are positioned behind the nine grid
pairs on the telescope. These artificially grown crystals, pure to over one
part in a trillion, were manufactured by the ORTEC division of PerkinElmer
Instruments. When they are cooled to cryogenic temperatures and a high voltage
is put across them (up to 4000 V), they convert incoming x-rays and gamma-rays
to pulses of electric current. The amount of current is proportional to the
energy of the photon, and is measured by sensitive electronics designed at the
Lawrence Berkeley National Laboratory and the Space Sciences Lab., Berkeley.

The detectors are cooled with a recently developed electromechanical cryocooler
(built by Sunpower, Inc. and flight qualified at Goddard. It maintains them at
the required operating temperature of minus 324 degrees Fahrenheit (minus 198
degrees Centigrade, or 75 degrees above absolute zero).

For more information, see:
http://hesperia.gsfc.nasa.gov/hessi/instrumentation.htm

Online Resources
http://hesperia.gsfc.nasa.gov/hessi/hessispec.htm

Instrument Logistics
Instrument Start Date: 2002-02-05
Instrument Owner: NASA/GSFC