Work Package 2

Radioactive source preparation compatible with novel cryogenic
detectors for absolute activity determination, comparison with
established activity standardisation techniques and high-resolution
spectrometry of selected radionuclides

In pioneering studies of LTDs for the calorimetric spectrometry of radioactive decays, systematic distortions of
the spectrum shape and energy scale have been observed and were attributed to the chemical composition
of the source material and its preparation technique, especially when using radioactive material in form of
dissolved salts or organic molecules in liquid solutions. Since it was not a major focus in the low-temperature
community to improve on that, it took several years to employ other techniques such as electro-deposition and
ion-implantation. Both techniques are expected to show a low influence (electro-deposition) or no influence
(ion-implantation) on the spectrum shape within the achieved energy resolution of the used LTDs.
Unfortunately, different preparation techniques come with different challenges. Electrodeposition requires the
development of an element-specific process, which is especially difficult for the low ion-concentrations, that
are usually present in radionuclide solutions. Moreover, the radioactive solutions used for the deposition should
have a low carrier concentration which is often not the case for commercially available materials. Ionimplantation on the other hand requires large scale and specialised facilities, e.g. mass separators, that, in
addition, must accept to operate with radioactive target materials.
The aim of WP2 is to develop a compromise between the different source preparation techniques in the
different measurement scenarios, namely the primary activity standardisation (WP3) and high-resolution
spectrometry (WP4).