Sounding rocket experiment employing microcalorimeter detectors to obtain a high-resolution spectrum of the diffuse x-ray background

We have developed microcalorimeters for high resolution soft X- ray spectroscopy that achieve an energy resolution of approximately eV FWHM. An adiabatic demagnetization refrigerator system has been constructed that will survive a sounding rocket launch and maintain the required 60 mK operating temperature following the approximately 17 g rms vibration associated with powered flight. Results of vibration tests show that both mechanical and thermal performance readily meet the requirement for using these detectors successfully on sounding rocket flights. The first flight of this system is intended to produce a high resolution spectrum of the 0.1-1.0 keV diffuse X-ray background, integrated over a approximately 1 steradian field of view. The same cryostat and detector system (36-pixel array) can be flown at the focus of a conical foil imaging mirror to do spatially resolved spectroscopy of supernova remnants and other extended source on future flights.