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Laboratory Astrophysics using a Microcalorimeter and Bragg Crystal Spectrometer on an Electron Beam Ion TrapWhen we last reported, our new microcalorimeter system was being prepared for delivery and permanent installation at the NIST EBIT. This occurred in June 2003 and check-out with the internal calibration source and EBIT plasma x-rays took place over the next several months during which time we modified several component parts to improve the performance. These changes included: 1) A redesign of the x-ray calibration source from a direct electron impact source to one that irradiates the microcalorimeter with fluorescent x-rays. The resulting calibration lines are free of bremsstrahlung background; 2) The microcalorimeter electronic circuit has been significantly improved to ensure long-term stability for the lengthy upcoming runs of the EBIT. Both the preamplifier feedback resistors were changed and the first stage of the preamplifier redesigned. Several photos of the new system are shown in slides 3 and 4. This microcalorimeter spectrometer only requires helium refills every three days (as opposed to every 24 hours in our earlier system) and it will hold a temperature of 65 mK for up to 48 hours (as opposed to 8 hours). Consequently, the efficiency of data acquisition will improve dramatically. The first x-ray spectra of the new calibration source made with the 4-element detector array is shown. An example of the temperature control capabilities of the ADR for a 23 hour interval is shown. The horizontal line shows the temperature stability (about +/- 3 micro kelvin). There are a few short-lived heating excursions caused by technical staff working on the EBIT machine simultaneously. During actual experimental runs these are absent. This temporal profile was interrupted to test additional components of the system; otherwise, the temperature controlling would have continued for another 24 hours.
Document ID
20040047165
Acquisition Source
Goddard Space Flight Center
Document Type
Contractor or Grantee Report
Authors
Silver, Eric
(Smithsonian Astrophysical Observatory Cambridge, MA, United States)
Date Acquired
August 21, 2013
Publication Date
March 1, 2004
Subject Category
Astrophysics
Report/Patent Number
Rept-2
Funding Number(s)
CONTRACT_GRANT: NAG5-5362
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.
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