The Selena Neutrino Experiment

TL;DR

This paper explores the development of a novel solid-state imaging sensor using amorphous selenium coupled with CMOS technology for neutrino detection, emphasizing high spatial resolution and background rejection capabilities.

Contribution

It reports the ionization response of amorphous selenium to gamma rays and progress in fabricating prototype sensors with CMOS charge readout for neutrino physics applications.

Findings

Measured ionization response of aSe to 122 keV gamma rays.

Progress in fabricating and testing prototype sensors.

Exploration of scientific potential for large neutrino detectors.

Abstract

Imaging sensors made from an ionization target layer of amorphous selenium (aSe) coupled to a silicon complementary metal-oxide-semiconductor (CMOS) active pixel array for charge readout are a promising technology for neutrino physics. The high spatial resolution in a solid-state target provides unparalleled rejection of backgrounds from natural radioactivity in the search for neutrinoless $\beta\beta$ decay and for solar neutrino spectroscopy with $^{82}$Se. We present results on the ionization response of aSe measured from the photoabsorption of 122 keV $\gamma$ rays in a single-pixel device. We report on the progress in the fabrication and testing of the first prototype imaging sensors based on the Topmetal-II$^{\rm -}$ pixelated CMOS charge readout chip. We explore the scientific reach of a large neutrino detector with the proposed technology based on our experimental understanding of the sensor performance.