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Description
The HEXITEC and HEXITECMHz detector systems have been developed for spectroscopic X-ray imaging for photon science applications. Both systems consist of 80 × 80 pixels on a 250 $\mu$m pitch and utilise high-Z sensor materials for detection of X-rays in the energy range 2 – 200 keV. The original HEXITEC system was capable of operating at a maximum frame rate of 9 kHz allowing per-pixel spectroscopy with an energy resolution of 800 eV to be captured at photon fluxes of up to 104 photons s-1 mm-2 [1]. The 1 MHz continuous frame rate of the HEXITECMHz means that the same spectroscopic imaging can be carried out at photon fluxes of the order 107 photons s-1 mm-2.
In this paper an update will be given on the current status of the HEXITEC technology and examples of how this has been applied for materials science applications. These examples will include the imaging and characterisation of in-operando lithium-ion batteries conducted at the I12 – JEEP beamline at the Diamond Light Source. In this experiment a monochromatic beam of 115 keV X-rays was used to illuminate a 0.25 mm thick slice through the width of a battery coin cell. The Compton scattered X-rays at 90 degrees to the battery were projected through a 0.2 mm pinhole to form an image on a 2 mm thick Redlen HF-CdZnTe HEXITEC detector. Images of the Compton signal were formed by integrating the counts around 93 keV with an integration time of 15 to 60 minutes. The strength of the Compton signal recorded at the detector was proportional to the ion density in the coin cell which evolves over the charging and discharge cycle. The battery cell was moved vertically through the beam to image slices through the cathode region of the battery cell. Using this technique, it was possible to image changes in the energy density of the battery during the charging and discharging cycle [2].
[1] M. C. Veale, et al., HEXITEC: A High Energy X-ray Spectroscopic Imaging Detector for Synchrotron Applications, Synchrotron Radiation News, 31, (6), 28-32, 2018. DOI:10.1080/08940886.2018.1528431
[2] K. Suzuki, et al., In operando quantitation of Li concentration for a commercial Li-ion rechargeable battery using high-energy X-ray Compton scattering, J. Synchrotron Rad., 24, 1006-1011, 2017. DOI:10.1107/S1600577517010098
