  The analysis of proteins in the gas phase benefits from detectors that
exhibit high efficiency and precise spatial resolution. Although modern
secondary electron multipliers already address numerous analytical
requirements, new methods are desired for macromolecules at low energy.
Previous studies have proven the sensitivity of superconducting detectors to
high-energy particles in time-of-flight mass spectrometry. Here we explore a
new energy regime and demonstrate that superconducting nanowire detectors are
exceptionally well suited for quadrupole mass spectrometry. Our detectors
exhibit an outstanding quantum yield at remarkably low impact energies.
Notably, at low ion energy, their sensitivity surpasses conventional ion
detectors by three orders of magnitude, and they offer the possibility to
discriminate molecules by their impact energy and charge. By combining these
detectors into arrays, we demonstrate low-energy ion beam profilometry, while
our cryogenic electronics pave the way for future developments of highly
integrated detectors.
