Optimization of Time- and Code-Division-Multiplexed Readout for Athena X-IFU.

Readout of a large, spacecraft-based array of superconducting transition-edge sensors (TESs) requires careful management of the layout area and power dissipation of the cryogenic-circuit components. We present three optimizations of our time- (TDM) and code-division-multiplexing (CDM) systems for the X-ray Integral Field Unit (X-IFU), a several-thousand-pixel-TES array for the planned Athena-satellite mission. The first optimization is a new readout scheme that is a hybrid of CDM and TDM.

Demonstration of Athena X-IFU Compatible 40-Row Time-Division-Multiplexed Readout.

Time-division multiplexing (TDM) is the backup readout technology for the X-ray Integral Field Unit (X-IFU), a 3,168-pixel X-ray transition-edge sensor (TES) array that will provide imaging spectroscopy for ESA's Athena satellite mission. X-0IFU design studies are considering readout with a multiplexing factor of up to 40. We present data showing 40-row TDM readout (32 TES rows + 8 repeats of the last row) of TESs that are of the same type as those being planned for X-IFU, using measurement and analysis parameters within the ranges specified for X-IFU.

Microcalorimeter energy-dispersive spectrometry using a low voltage scanning electron microscope.

We describe the current performance of the prototype microcalorimeter energy-dispersive spectrometer (&mgr;cal EDS) developed at NIST for X-ray microanalysis. We show that the low-energy &mgr;cal EDS, designed for operation in the energy range 0.2-2 keV, offers significant advantages for low-beam-energy microanalysis.

The preparation of cross-sectional transmission electron microscopy specimens of Nb/Al multilayer thin films on sapphire substrates.

We have developed a technique for preparation of cross-sectional transmission electron microscopy samples of reacted and unreacted Nb/Al multilayer thin films on sapphire substrates. The choice of substrate was found to be extremely important. Sapphire sputters more slowly than Nb and Nb-compounds and therefore makes it possible to obtain the electron transparent regions in the thin films rather than in the substrate.