A new array detector for dose measurements in laser generated ultrashort proton beams used for radiobiology experiments

• Main Author: Popovici, Maria Ana
• Format: Web Resource
• Language: English
• Published: Morressier 01.01.2017
• DOI: 10.26226/morressier.5cb7218eae0a090015830689

One of the research directions at the ELI-NP research infrastructure in Romania, using 10 PW lasers, is to provide more insight regarding the biological effectiveness of the proton beams. One major problem is the in-beam dosimetry for these experiments, not in the least due to the extreme shortness of the pulses. Due to the specifics of the laser pulse, the proton beams generated by laser acceleration have a lenght of only a few nanoseconds, which means that measurements with ion chambers will be affected by large recombination correction factors. Measuring those recombination factors through the usual method is not an option because the laser frequency is rather low (0.1 Hz is to be achieved) and, at least in the begining, the pulses will not be highly repeatable).Therefore, we have developed an array of four chambers, each polarised at a different voltage. The chamber array is now being tested in various charged particle fields, and the present paper shows the results obtained in a low energy proton beam and in electron beams generated by clinical LINACs. In order to determine the distance between the chambers, FLUKA simulations were used to calculate the reciprocal influences of the four chambers. The recombination correction factor was then determined in 5 MeV electron, first by the classical method than using the array detector and the differences between the two are presented. We can safely conclude that the array can be used with good results for the dosimetry in ultrashort pulses of charged particle beams.