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VERSION:2.0
CALSCALE:GREGORIAN
PRODID:UW-Madison-Physics-Events
BEGIN:VEVENT
SEQUENCE:2
UID:UW-Physics-Event-8989
DTSTART:20241122T150000Z
DTEND:20241122T170000Z
DTSTAMP:20260405T193112Z
LAST-MODIFIED:20241114T144551Z
LOCATION:6242 Chamberlin Hall or https://uwmadison.zoom.us/j/915203127
 25?pwd=bCtnVGhybFhLOTRsQlJ1NkhnVmdWQT09
SUMMARY:Pulsed-laser calibration of thermal microcalorimeters for X-ra
 y astronomy\, Thesis Defense\, Avirup Roy\, Physics PhD Graduate Stude
 nt
DESCRIPTION:The performance of single photon microcalorimeters for hig
 h-resolution X-ray spectroscopy has improved to the point that it can 
 be limited by our ability to calibrate these detectors. X-ray fluoresc
 ent lines have been the usual standard for calibrations\, but they hav
 e intrinsic widths much broader than the current detector resolution. 
 Since microcalorimeters respond to total energy deposited as heat\, we
  have investigated the idea that five hundred 3 eV photons from an ult
 raviolet laser delivered in a pulse much shorter than the thermal inte
 gration time of detectors should look the same as a single 1500 eV X-r
 ay photon.
\n
\nWe have illuminated devices that have 290 μm square g
 old absorbers\, superconducting transition-edge sensor (TES) thermomet
 ers\, and about 1 eV FWHM resolution with ∼ 100 ns pulses from an ul
 traviolet laser. This produces combs of lines with 3 eV spacing and ne
 gligible intrinsic width that can be distinguished to at least 1700 eV
 . The accuracy of the line energies is limited only by our knowledge o
 f the laser wavelength. Simultaneous illumination with oxygen and alum
 inum K fluorescent lines shows that the response to an X-ray photon is
  indistinguishable from the response to a burst of UV photons with the
  same total energy to better than 0.4 eV at 1500 eV. This performance 
 is more than adequate for our current sounding rocket instrument. We d
 iscuss the path forward to possibly demonstrating the 0.1 eV at 10 keV
  standard that would be desirable for instruments on major space missi
 ons.
\n
URL:https://www.physics.wisc.edu/events/?id=8989
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