Imaging low-energy positron beams in real-time with unprecedented resolution

Abstract

Abstract Particle beams focused to micrometer-sized spots play a crucial role in forefront research using low-energy positrons. Their expedient and wide application, however, requires highly-resolved, fast beam diagnostics. We have developed two different methods to modify a commercial imaging sensor to make it sensitive to low-energy positrons. The first method consists in removing the micro-lens array and Bayer filter from the sensor surface and depositing a phosphor layer in their place. This procedure results in a detector capable of imaging positron beams with energies down to a few tens of eV, or an intensity as low as $${35}\,{\hbox {e}^+/\hbox {s/mm}^{2}}$$ 35 e + / s/mm 2 when the beam energy exceeds 10 $${\hbox {keV}}$$ keV . The second approach omits the phosphor deposition; with the resulting device we succeeded in detecting single positrons with energies upwards of $${6}\,{\hbox {keV}}$$ 6 keV and efficiency up to 93%. The achieved spatial resolution of 0.97 $$\upmu \hbox {m}$$ μ m is unprecedented for real-time positron detectors.