A technique involving ^{55}Fe X-rays provides a straightforward method to
measure the response of a detector. The detector's response can lead directly
to a calculation of the conversion gain (e^- ADU^{-1}), as well as aid detector
design and performance studies. We calibrate the ^{55}Fe X-ray energy response
and pair production energy of HgCdTe using 8 HST WFC3 1.7 \micron flight grade
detectors. The results show that each K$\alpha$ X-ray generates 2273 \pm 137
electrons, which corresponds to a pair-production energy of 2.61 \pm 0.16 eV.
The uncertainties are dominated by our knowledge of the conversion gain. In
future studies, we plan to eliminate this uncertainty by directly measuring
conversion gain at very low light levels.Comment: 17 pages, 7 Figures, 2 Table. Accepted for publication on PAS

Foltz, Roger D.

Fox, Ori D.

Hill, Robert J.

Kimble, Randy A.

Malumuth, Eliot

Rauscher, Bernard J.

Waczynski, Augustyn

Wen, Yiting

English

arXiv

The accurate determination of a detector's fundamental parameters, including read noise, dark current, and QE, relies on a proper measurement of a detector's conversion gain (e- ADU(exp -1)). Charge coupling effects, such as interpixel capacitance, attenuate photon shot noise and result in an overestimation of conversion gain when implementing the photon transfer technique. An approach involving (55)Fe X-rays provides a potentially straightforward measurement of conversion gain by comparing the observed instrumental counts (ADU) to the known charge (e-) liberated by the X-ray. This technique is already preferred within the CCD community, as the pair production energy for silicon is well established. In contrast, to date the pair production energy is unknown for HgCdTe, a material commonly used for near-infrared detectors. In this paper, we derive a preliminary calibration of the (55)Fe X-ray energy response of HgCdTe using 8 HST WFC3 1.7 micrometers flight grade detectors. Our conversion of the X-ray intensities from counts into electrons implements a technique that restores the 'true' gain via classical propagation of errors. For these detectors, our analysis yields preliminary results of good statistical precision: each Ka event generates 1849 +/- 46 electrons, which corresponds to a pair production energy of 3.21+/-f 0.08 eV. We are continuing to assess potential systematic effects to further refine the accuracy of this result

Hill, Robert F.

Fox, Ori

NASA Technical Reports Server

The (55)Fe X-ray Energy Response of Mercury Cadmium Telluride Near-Infrared Detector Arrays

A technique involving Fe-55 X-rays provides a straightforward method to measure the response of a detector. The detector's response can lead directly to a calculation of the conversion gain (e(-) ADU(-1) ), as well as aid detector design and performance studies. We calibrate the Fe-15 X-ray energy response and pair production energy of HgCdTe using 8 HST WFC3 1.7 micron flight grade detectors. The results show that each Ka X-ray generates 2273 +/- 137 electrons, which corresponds to a pair-production energy of 2.61 +/- 0.16 eV. The uncertainties are dominated by our knowledge of the conversion gain. In future studies, we plan to eliminate this uncertainty by directly measuring conversion gain at very low light levels

Kimble, Randa A.

Waczynaski, Augustyn

The 55Fe X-ray Energy Response of Mercury Cadmium Telluride Near-Infrared Detector Arrays

The ^{55}Fe X-ray Energy Response of Mercury Cadmium Telluride
  Near-Infrared Detector Arrays

The ^{55}Fe X-ray Energy Response of Mercury Cadmium Telluride Near-Infrared Detector Arrays

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