Detachable three-layer Au absorber microfabrication for low-temperature detectors

Abstract

Low temperature detectors (LTDs) used for decay energy spectrometry (DES) can provide accurate and reliable decay data thanks to their high-energy resolution and a near 100% detection efficiency for the radiations of interest. However, it is essential to consider the source quality to mitigate spectral distortion due to the self -absorption of particle energy in the source deposited. This work aimed to produce a replaceable 4 & pi; 3-layer gold absorber for DES in reusable metallic magnetic calorimeters, a class of LTDs. We present a novel 3-layer microfabrication process for a 1 mm diameter absorber with a total gold thickness ranging from 20 & mu;m to 120 & mu;m depending on the measured radionuclide (55Fe or 241Am). The absorber integrates a gold nanofoam in which the radionuclide is deposited by nanodrop deposition of a few tenths of & mu;L of a radioactive solution. We fabricated a high quality gold nanofoam layer with controllable porosity through a dealloying process using wet etching and integrating it on a thick electrodeposited gold layer. The fine study of the nanofoam microfabrication is performed using high-resolution scanning electron micro-scopy (SEM) and energy dispersive x-ray spectroscopy (EDX).