  We report the test results for a 120 GeV proton beam incident on
superconducting nanowire particle detectors of various wire sizes. NbN devices
with the same sensitive area were fabricated with different wire widths and
tested at a temperature of 2.8 K. The relative detection efficiency was
extracted from bias current scans for each device. The results show that the
wire width is a critical factor in determining the detection efficiency and
larger wire widths than 400 nm leads to inefficiencies at low bias currents.
These results are particularly relevant for novel applications at accelerator
facilities, such as the Electron-Ion Collider, where cryogenic cooling is
readily available.
