Conférences et séminaires » Séminaire présenté par Till SOHIER, IPHC
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High energetic Hadron relative dosimetry : a nanosecond time resolution fluorescence measurement method to discriminate excitation and ionisation process in plastic scintillators
Par : Till SOHIER, IPHC
Date : vendredi 8 mars 2013 à 10h30
Lieu : IPHC, Salle de Réunion 2e étage du Bâtiment 27
The National Institute of Radiological Sciences (NIRS) is the world leading institute in hadrontherapy field, indeed it has treated more than 6000 patients using this oncological technique by May 2011.
Organic scintillators have been used as radioactivity sensors monitors in a wide range of scientific fields, including medical science, physical science and engineering. For manufacturing and costs reason they have become quite indispensable in research.
During the period 2010-2012 we developed and tested in collaboration with the NIRS using the Heavy Ion Accelerator in Chiba (HIMAC), a new scintillation measurement method for relative hadron dosimetry. Emitted fluorescence is measured by Time Correlated Single Photon Counting (TCSPC) method using a plastic scintillator. Our experimental approach consists of plastic scintillators used to convert deposited energy into scintillation, which is collected by two photodetectors (typically photomultipliers tubes) in order to avoid photodetectors saturation. TCSPC method is linear on a large dose rate scale independently to the charge of the incident hadron. It exhibits higher spatial resolution in the bragg peak measurement than the conventional method used, based on ionisation chamber.
We were able, for the first time, to discriminate, with heavy ions, the ionization process from the excitation process and therefore to virtually reconstruct an ionization chamber. We will also present a new physical observable which is highly correlated with the Z value of the incident hadron.