Scintillation properties of N2 and CF4 and performances of a scintillating ionization chamber

International audienceIn this work, we studied the emission yields, decay times and coincidence resolving times (CRT) of two gases, nitrogen (N2) and tetrafluoromethane (CF4), used for particle detection in the context of fission products measurement. The setup was made of an ionization chamber and two photomul-tiplier tubes (PMTs) placed front-to-front on each side of the active zone of the chamber. Using the photomultiplier tubes, the number of photoelectrons (phe) converted at the photocathodes from the scintillation processes in each gas were quantified and the scintillation time spectra were recorded. An scintillation emission yield of 24 phe MeV −1 with a decay time of τ d = 2.5 ns in N2, and 225 phe MeV −1 with τ d = 6.2 ns for CF4, have been measured. With our setup , the coincidence resolving time (σ values) between the two PMTs have been measured at 1.4 ns and 0.34 ns for N2 and CF4 respectively, using alpha particles

Elements Discrimination in the Study of Super-Heavy Elements using an Ionization Chamber

Dedicated ionization chamber was built and installed to measure the energy loss of very heavy nuclei at 2.7 MeV/u produced in fusion reactions in inverse kinematics (beam of 208Pb). After going through the ionization chamber, products of reactions on 12C, 18O targets are implanted in a Si detector. Their identification through their alpha decay chain is ambiguous when their half-life is short. After calibration with Pb and Th nuclei, the ionization chamber signal allowed us to resolve these ambiguities. In the search for rare super-heavy nuclei produced in fusion reactions in inverse or symmetric kinematics, such a chamber will provide direct information on the nuclear charge of each implanted nucleus.Comment: submitted to NIMA, 10 pages+4 figures, Latex, uses elsart.cls and grahpic

A new scintillating fiber dosimeter using a single optical fiber and a CCD camera

Radiotherapy treatments become more and more accurate, using very small irradiation fields and complex dose depositions. So small dosimeters for real time and in vivo dosimetry, suitable for photons as well as for electrons beams are highly desired. In this context, a scintillating fiber dosimeter (SFD) has been developed by the Laboratoire de Physique Corpusculaire de Caen (LPC Caen), France, in collaboration with one of the French regional center for cancer treatment Centre Regional de lutte contre le cancer F. Baclesse (CRLCC F. Baclesse), Caen, France, and the ELDIM Company, Herouville, France. This plastic dosimeter is water equivalent, and it is suitable for photons as well as for electrons beams without correction. It is a real time dosimeter, with an excellent signal to noise ratio, and a spatial resolution of about a few millimeters. The aim of this study was to reduce the size of the scintillator in order to improve the spatial resolution of this dosimeter. So, a new light collection device has been developed to reduce the length of the scintillator from 1 cm to 1 mm without loss in the signal to noise ratio. The accuracy of this improved prototype has been tested by comparison with standard ionization chambers and the difference between the two devices never exceeded one percent for photon and for electron irradiation beams. A first set of commercial SFD is under completion at ELDIM and it will be soon clinically tested in several French centers for cancer treatment

12C nuclear reaction measurements for hadrontherapy

International audienceHadrontherapy treatments require a very high precision on the dose deposition ( 2.5% and 1-2mm) in order to keep the benefits of the precise ions' ballistic. The largest uncertainty on the physical dose deposition is due to ion fragmentation. Up to now, the simulation codes are not able to reproduce the fragmentation process with the required precision. To constraint the nuclear models and complete fragmentation cross sections databases; our collaboration has performed an experiment on May 2008 at GANIL with a 95 MeV/u 12C beam. We have measured the fluence, energy and angular distributions of charged fragments and neutrons coming from nuclear reactions of incident 12C on thick water-like PMMA targets. Preliminary comparisons between GEANT4 (G4BinaryLightIonReaction) simulations and experimental data show huge discrepancies

Dispositif et procédé d'inspection d'un faisceau ionisant

La présente invention concerne un dispositif d'inspection d'un faisceau avec: une tête d'inspection (110) comprenant un scintillateur (114) et au moins un bloc diffuseur (116, 117) associé au scintillateur, un premier moyen (118) de formation d'au moins une image d'au moins une partie de la tête d'inspection comprenant le scintillateur. Conformément à l'invention, le scintillateur comporte au moins une plaque massive et sensiblement homogène de matériau de scintillation présentant deux faces principales opposées. Application à la radiothérapie

Dispositif et procédé d'inspection d'un faisceau ionisant

La présente invention concerne un dispositif d'inspection d'un faisceau avec: une tête d'inspection (110) comprenant un scintillateur (114) et au moins un bloc diffuseur (116, 117) associé au scintillateur, un premier moyen (118) de formation d'au moins une image d'au moins une partie de la tête d'inspection comprenant le scintillateur. Conformément à l'invention, le scintillateur comporte au moins une plaque massive et sensiblement homogène de matériau de scintillation présentant deux faces principales opposées. Application à la radiothérapie