Speakers
Description
The goal of the SURF$\alpha$CE (Silicon Underground Radiopure Finder of $\alpha$ Contamination Excesses) $\alpha$ spectrometer is to demonstrate the possibility to measure the surface radioactive contamination of the $^{232}$Th and $^{238}$U decay chains with an unprecedented sensitivity of 1 nBq/cm$^2$, a value demanded by several next-generation experiments for rare event searches. The SURF$\alpha$CE detector concept consists of an array of large-area silicon wafers instrumented as bolometers and interleaved with material samples.
Provided that a total sensitive area of 1 m$^2$, an energy resolution <10 keV FWHM, and an expected background of $10^{-8}$ counts/s/cm$^2$ in the full $\alpha$ range from 3 to 10 MeV are achieved, SURF$\alpha$CE will surpass the existing $\alpha$ detector technology by two orders of magnitude, and be capable of separately measuring parts of the $^{232}$Th and $^{238}$U chains that are out of secular equilibrium.
Thanks to the recent advancements in the technology of dilution refrigerators and bolometers, the development of such a large-area cryogenic detector dedicated to $\alpha$ screening measurements is now feasible. SURF$\alpha$CE will be located underground at the Laboratori Nazionali del Gran Sasso (LNGS), Italy, and will aim at demonstrating the feasibility, reproducibility and scalability of a bolometer for $\alpha$ measurements with a 1 nBq/cm$^2$ sensitivity, and at realizing a new-generation screening facility for surface contamination measurements.
In this talk, we will present the detector design, the results obtained from the preliminary studies of the detector response, and the plans for the realization of the full-scale setup.