Preliminary microdosimetric measurements with ultra-thin 3D silicon detectors of a 62 MeV proton beam

In this paper we present the first direct microdosimetric measurements of 62 MeV proton beams using ultra-thin 3D silicon detectors at different depths in a solid-water phantom. The detectors have 3D columnar electrodes that penetrate a 10 μm thick silicon membrane, resulting in a micrometric scale sensitive volume. The 62 MeV proton beam was generated in a cyclotron CYCLONE-110 at Centre de Recherches du Cyclotron (CRC) at Louvain-la-Neuve. The proton beam average energy was modulated with stacked tissue-equivalent solid water layers. The energy loss profile was studied through the Bragg curve and pulse height spectra. The experimental silicon microdosimetric spectra showed the lineal energy dependence along the Bragg curve. This work demonstrates the potential capability of the ultra-thin 3D silicon detectors as 3D detector technology-based microdosimeters