科研之友
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摘要
We are developing a narrow line calibration source for use with X-ray microcalorimeters. At energies below 300 eV fluorescent lines are intrinsically broad, making calibration of high resolution detectors difficult. This source consists of a 405 nm (3 eV) laser diode coupled to an optical fiber. The diode is pulsed to create approximately one hundred photons in a few microseconds. If the pulses are short compared to the rise time of the detector, they will be detected as single events with a total energy in the soft X-ray range. Poisson fluctuations in photon number per pulse create a comb of X-ray lines with 3 eV spacing, so detectors with energy resolution better than 2 eV are required to resolve the individual lines. Our currently unstabilized diode has a multimode width less than 1 nm, giving a 300 eV event a FWHM less than 0.1 eV. By varying the driving voltage, or pulse width, the source can produce a comb centered on a wide range of energies. The calibration events are produced at precisely known times. This allows continuous calibration of a flight mission without contaminating the observed spectrum and with minimal deadtime.
- 出版日期2014-8
