https://doi.org/10.1140/epjd/e2014-40841-0
Regular Article
A novel approach to study radiation track structure with nanometer-equivalent resolution*
1
Center for Proton Therapy, Paul Scherrer Institut,
5232
Villigen PSI,
Switzerland
2
Department of Basic Sciences, Loma Linda University,
11175 Campus St., Loma Linda, CA
92350,
USA
3
Department of Radiation Medicine, Loma Linda University Medical
Center, 11234 Anderson
St., Loma Linda,
CA
92354,
USA
a
e-mail: margherita.casiraghi@psi.ch
Received: 31 December 2013
Received in final form: 8 March 2014
Published online: 7 May 2014
Clustered DNA damages are considered the critical lesions in the pathways leading from the initial energy deposition by radiation to radiobiological damage. The spatial distribution of the initial DNA damage is mainly determined by radiation track-structure at the nanometer level. In this work, a novel experimental approach to image the three-dimensional structure of micrometric radiation track segments is presented. The approach utilizes the detection of single ions created in low-pressure gas. Ions produced by radiation drift towards a GEM-like 2D hole-pattern detector. When entering individual holes, ions can induce ion-impact ionization of the working-gas starting a confined electron avalanche that generates the output signal. By registering positive ions rather than electrons, diffusion is reduced and a spatial resolution of the track image of the order of water-equivalent nanometers can be achieved. Measurements and simulations to characterize the performance of a few detector designs were performed. Different cathode materials were tested and ionization cluster size distributions of 241Am alpha particles were measured. The electric field configuration in the detector was calculated to optimize the ion focusing into the detector holes. The preliminary results obtained show the directions for further development of the detector.
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag 2014
