Micro-collimators fabricated by chemical etching of thin polyallyldiglycol carbonate polymer films exposed to oxygen ions

One approach for a particle radiobiological experiments is to use solid-state nuclear track detectors (SSNTDs) as support substrates to record the a particle hit positions on the targets. To facilitate accurate characterization of the hit positions as well as the incident a particle energies, micro-collimators are required in these experiments to restrict the incidentaparticles to thosewith small deviations fromnormal incidence with respect to the collimator. In the present paper, we fabricated micro-collimators, which restricted a particles to those with deviations as low as 121. Specially etched polyallyldiglycol carbonate (PADC) films, which are a kind of SSNTD, with a thickness 70 mm were prepared from commercially available PADC films. Thesewere then irradiated by 4.83 MeV/n oxygen ions generated from the heavy-ion medical accelerator inChiba (HIMAC), Japan. The irradiatedfilmswere chemically etched forat least 2.7 h to achieve etched-through air channels to form the micro-collimators. The micro-collimators formed by etching the irradiated films for 2.7, 3.0 and4.0 hwere experimentally showntobeable to restricta particles to those very close to normal incidence. In contrast, the micro-collimator formed by etching the irradiated film for 4.5 h started to allow a particles with larger deviations from normal incidence to pass through, which is likely due to overlapping of air channels from excessive etching. & 2010 Elsevier B.V. All rights reserved.