An Inkjet-Based Microsphere Loading System for Optical Precision Levitation in Sterile Neutrino Searches

The Search for new Interactions in a Microsphere Precision Levitation Experiment (SIMPLE) uses levitated quantum optomechanical sensors to search for sterile neutrinos. SIMPLE is sensitive to sterile neutrinos in the keV-MeV mass range, where they could account for some (or all) of dark matter, by tracking the recoiling momenta of optically trapped radioisotopes undergoing β-decay or electron capture implanted in SiO2 microspheres with diameters between ~100 nm - 10 µm in vacuum. SIMPLE requires the efficient loading of isolated radioactive nanospheres or microspheres into the trap. Current loading methods are unacceptable for radioactive microparticles and create risk of contaminating the vacuum chamber with these radioisotopes. A new method for isolating and loading microspheres into optical traps will be presented, utilizing commonly available inkjet printer technology to generate aerosol microparticles of uniform size. Micro-sized droplets are produced, either continuously or in a drop-on-demand mode, by exciting a pressure wave in a piezoelectric with pulsed waveforms connected to an inkjet printer cartridge. I will describe progress towards realizing this loading system, as a step towards performing sterile neutrino searches with SIMPLE.