Response of a track-etch-based LET-spectrometer to high-energy protons

The spectrometer of linear energy transfer (LET) was developed. It is based on the chemically etched polyallyldiglycolcarbonate (PADC) track-etch detector. LET spectra are estimated through track parameter determination and analysed by an automatic optical image analyser LUCIA G. Three PADC materials were used: 0.5 mm thick Page, 0.5 and 1 mm thick Tastrak; they were exposed to protons with energies up to 1000 MeV. Such energetic protons are generally not directly registrable in any of PADCs mentioned; the tracks observed correspond mostly to secondary particles created through nuclear interactions of primary protons. LET spectra permit to calculate the dose absorbed in the detector due to these secondary particles and to compare it with the ionization collision dose of primary protons. It is observed that the dose due to secondary particles represents a few percent of the ionization collision dose. Their ratio varies slightly with proton energy, and some differences between the three PADCs used were also observed. The importance of results obtained for on-board spacecraft dosimetry is analysed and discussed.