Conception and realization of a parallel-plate free-air ionization chamber for the absolute dosimetry of an ultrasoft X-ray beam

Abstract

We report the design of a millimeter-sized parallel plate free-air ionization chamber (IC) aimed at determining the absolute air kerma rate of an ultra-soft X-ray beam (E = 1.5 keV). The size of the IC was determined so that the measurement volume satisfies the condition of charged-particle equilibrium. The correction factors necessary to properly measure the absolute kerma using the IC have been established. Particular attention was given to the determination of the effective mean energy for the 1.5 keV photons using the PENELOPE code. Other correction factors were determined by means of computer simulation (COMSOL™ and FLUKA). Measurements of air kerma rates under specific operating parameters of the lab-bench X-ray source have been performed at various distances from that source and compared to Monte Carlo calculations. We show that the developed ionization chamber makes it possible to determine accurate photon fluence rates in routine work and will constitute substantial time-savings for future radiobiological experiments based on the use of ultra-soft X-rays.

Low energy electrons and ultra-soft X-rays irradiation of plasmid DNA. Technical innovations

“…In the present case, the substrate is composed of freshly cleaved HOPG foils. The USX source is the Al K α line (1.5 keV) generated by using a lab-bench cold-cathode system (Ounoughi et al, 2013), with a well characterized beam, both spatially and energetically (Groetz et al, 2014), (Ounoughi et al, 2015).…”

Evidence for a critical dose above which damage to carbonate ester bonds in PADC appear after gamma ray and ultra soft X-ray exposures

“…The examined dose range was up to 180 kGy. The derivation process of the mean absorbed dose rate in a medium is presented elsewhere (Fullford et al, 1999;Groetz et al, 2014). In the energy region of USX, the photoelectric effect is the main interaction.…”

Complexation des acides aminés basiques arginine, histidine et lysine avec l’ADN plasmidique en solution aqueuse : participation à la capture de radicaux sous irradiation X à 1,5 keV

“…Les solutions complexes sont exposées en environnement atmosphérique à la raie Kα de l'aluminium à l'aide d'un générateur de rayons X à cathode froide dont le faisceau a été caracté-risé finement [9,10,11]. Le dispositif complet est schématisé en figure Ultra-Soft X-ray irradiation device.…”