2.3.2 Spectral Energy Response

The geometrical area of HXT, which is determined by the (average) transmission of the SC's, is 57.4 cm. When considering the spectral energy response of the HXT, the following components need be taken into account:

• thermal shield which wraps around the HXT collimator body
• grid wires made of tungsten (for top and bottom grid assemblies)
• face plates made of Carbon Fiber Reinforced Plastic (CFRP) for top and bottom grid assemblies)
• aluminum cases for NaI (Tl) scintillation crystals
• NaI (Tl) scintillation crystals

The spectral energy response for HXT, with the effect of K-escape of tungsten at 69.6 keV and measured energy resolution of NaI (Tl) + photomultiplier tubes taken into account, are summarized in a file whose name is obtained as follows:
IDL> file = concat_dir('$DIR_HXT_CAL', 'possi4.dat')
A concise summary of the energy spectral response, together with some useful figures, is provided in ``The Yohkoh HXT Databook (I).''