A new device using a laser-held bead has enabled the first direct measurement of pressure exerted by individual particles. Developed by researchers at Yale University, the tool could advance studies in extreme vacuums and help search for elusive particles like sterile neutrinos.
Yu-Han Tseng and colleagues created the instrument around a tiny silica sphere, roughly half the size of some viruses. A laser beam holds the bead in place through electromagnetic forces, and any particle collision shifts the sphere while reflecting detectable light signals. The team tested the setup in an ultra-high vacuum by introducing particles from three gases and confirmed that the observed motions matched theoretical predictions for pressure calculations.