Experimental calibration demonstrates target angular and energy resolution in the Helios ENA Rapid Mapper, indicating its readiness for imaging outer heliospheric boundary particles.
Key Points
Evaluate the energy and angular response of the Helios ENA Rapid MApper (HERMA) through comprehensive ground calibration to verify its readiness for imaging energetic neutral atoms at the heliospheric boundary.
Determined energy scale equations across all 256 semiconductor detector pixels using barium-133 (133Ba) and americium-241 (241Am) radioactive sources.
Tested energy response, angular resolution, and charged-particle deflection capabilities using proton and neutral hydrogen beams from a highly charged-ion platform.
Achieved energy resolutions ranging from 4.0% to 8.9% for 100 keV hydrogen atoms across the 256 detector pixels.
Measured an angular coverage exceeding 45° with angular resolutions of 0.22°–0.60° in the modulation direction (1.52° orthogonally in simulation).
Demonstrated that the integrated electrostatic deflection system effectively removes background 100 keV protons, satisfying all engineering performance specifications.