| High Energy X-ray Spectrometer (HEX) |
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| The High-Energy X-ray spectrometer covers the hard X-ray region from 30 keV to 270 keV. This is the first experiment to carry out spectral studies of planetary surface at hard X-ray energies using good energy resolution detectors. The High Energy X-ray (HEX) experiment is designed primarily to study the emission of low energy (30-270 keV) natural gamma-rays from the lunar surface due to 238U and 232Th and their decay chain nuclides. |
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| Scientific Objectives: |
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To identify excess 210Pb in lunar polar regions deposited there as a result of transport of gaseous 222Rn, a decay product of 238U from other regions of the Moon. This will enable us to understand transport of other volatiles such as water to the polar regions.
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To detect other radioactive emissions, to characterise various lunar terrains for their chemical and radioactive composition on the basis of specific/integrated signal in the 30-270 keV region.
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To explore the possibility of identifying polar regions covered by thick water-ice deposit from a study of the continuum background. |
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| Payload Configuration Details: |
The geometric detector area of 144 cm2 is realized by nine Cadmium Zinc Telluride (CZT) arrays, each 4 cm x 4 cm (5 mm thick), composed of 256 (16x16) pixels (size: 2.5 mm x 2.5 mm). Each CZT array is readout using two closely mounted Application Specific Integrated Circuits (ASICs), which provides self-triggering capability. The detector will be biased at the cathode with –550 V and the electronic charge signals are collected at the anode. A Cesium Iodide (CsI (Tl)) scintillator crystal coupled to photomultiplier tubes (PMT), will be used as the anticoincidence system (ACS). The ACS is used to reduce the detector background.
A specially designed collimator provides a field of view (FOV) of 33 km X 33 km at the lunar surface from a 100 km orbit. The spatial resolution of HEX is 33 km and the mass is 14.4 kg. |
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| HEX payload developed by ISRO |
