A Highly Linear Calibration Metric for TES X-ray Microcalorimeters

Area of Science:

• Physics
• Astrophysics
• Detector Physics

Background:

• Transition-edge sensor X-ray microcalorimeters are typically calibrated using empirical methods.
• The standard calibration metric, optimal filtered pulse height (OFPH), exhibits an unknown dependence on photon energy (Eγ), leading to calibration errors and extensive measurement requirements.
• A more linear calibration metric is needed to improve accuracy and reduce calibration time.

Purpose of the Study:

• To assess the linearity of a physically motivated calibration metric, E_Joule, for X-ray microcalorimeters.
• To compare the linearity of E_Joule with the conventional OFPH metric.
• To evaluate the performance of an optimized version, E_J, for calibration.

Main Methods:

• Calibration pulses were measured for photon energies between 4.5 keV and 9.6 keV.
• Detectors were optimized for 6 keV photons to facilitate direct comparison.
• The linearity of E_Joule and OFPH was analyzed using the measured data.

Main Results:

• E_Joule demonstrated an order of magnitude better fit to a linear function compared to OFPH in the tested energy range.
• The optimized metric, E_J, exhibited linearity within the 2-3 eV noise level of the data.
• These findings indicate a significant improvement in linearity over OFPH.

Conclusions:

• The E_Joule metric, and its optimized form E_J, offer a more linear and potentially more accurate calibration method for transition-edge sensor X-ray microcalorimeters.
• This improved linearity can reduce calibration errors and the need for time-consuming calibration procedures.
• The results suggest E_Joule is a promising alternative to OFPH for advanced X-ray detector calibration.