HXT Instrument

The HXT is a hard X-ray imager of the Fourier-synthesis type, consisting of 64 modulation subcollimators. Each modulation subcollimator is equipped with a small NaI(Tl) scintillator and photomultiplier tube, and measures a modulated photon count. A set of the 64 photon counts, transmitted from the satellite to the ground, is converted into an image by an image synthesis procedure, e.g., MEM, PIXON, and CLEAN. The main characteristics of HXT are summarized below:

i) Simultaneous imaging in four energy bands, namely, the L-band (13.9 - 22.7 keV), M1-band (22.7 - 32.7 keV), M2-band (32.7 - 52.7 keV), and H-band (52.7 - 92.8 keV).

ii) Angular resolution of about 5 arcsec with a wide field of view covering the whole Sun.

iii) Basic temporal resolution of 0.5 s.

iv) High sensitivity with an effective area of about 60 cm2.

For more detail, see Kosugi et al., Solar Phys., 136, 17-36, 1991.

The spectral response of the HXT instrument is summarized in a table and figures below.

Table 1: Spectral Response

Figure 1: Effective Filter Characteristics

Figure 2: Energy Resolution

Figure 3: Probability of Photon Detection

Figure 4: Contribution of Incident Photons/keV

Figure 5: Count Ratio vs Incident Photon Spectrum (Power-Law Spectrum)

Figure 6: Count Ratio vs Incident Photon Spectrum (Thermal Spectrum)

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