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Reference : UMR5821-CHRVEL-093
Workplace : GRENOBLE
Date of publication : Monday, June 7, 2021
Scientific Responsible name : Marie-Laure GALLIN-MARTEL
Type of Contract : PhD Student contract / Thesis offer
Contract Period : 36 months
Start date of the thesis : 1 October 2021
Proportion of work : Full time
Remuneration : 2 135,00 € gross monthly
Description of the thesis topic
Design of a diamond beam monitor demonstrator DIAMMONI for on-line control of pulsed beams: applications to radiolysis and innovative "Flash" radiotherapy.
The development of new generations of ion accelerators, for physics (nuclear - high energy) or for medical applications (“Flash” radiotherapy) with associated research (radiolysis, radiobiology and preclinical), involves precise monitoring of the beam including particle counting in a highly radiative environment.
Online beam monitors typically use ion chambers to measure the geometric characteristics of the beam and its intensity. However, the response of these conventional monitors is not linear with the dose, in particular for high doses (radiolysis), moreover, it has been observed that this response may also depend on the dose rate. In the envisaged applications, this may vary between 0.015Gy / sec (conventional irradiation of a few minutes) and more than 40Gy / sec ("Flash" irradiation for a period of up to a hundred milliseconds).
The intrinsic qualities of diamond (high speed, low leakage current, excellent signal-to-noise ratio, resistance to radiation) make it an excellent candidate to meet such beam monitoring requirements. DIAMMONI is an innovative diamond detector for on-line monitoring of pulsed beams. Its objective is to achieve a spatial resolution of the order of a millimeter (stripped metallization), a rapid counting of the particles in each nano-pulse of each micro-pulse train (time resolutions ~ 100 ps) as well as continuous monitoring of the beam intensity over the entire dynamic (fraction of pA to µA). In this application, the diamond will be used as a solid state ionization chamber.
The thesis subject relates to the simulations, developments and experiments of a complex system composed of a beam monitor, the active part of which will consist of diamond detectors read by a Front-End electronics and an acquisition system developed in the laboratory by the technical services involved in the ANR-DIAMMONI project.
In parallel, Flash irradiations for radiolysis, radiobiology and preclinical studies (68 MeV proton and alpha) will be carried out with ARRONAX beams. This will involve precisely monitoring the beam (delivered dose, beam profile) over a wide range of dose (0.1-100 Gy) and dose rate (<1 MGy / sec).
The various prototypes developed will have to be installed as they are designed on the ARRONAX line in order to characterize their performance and optimize their development to lead, at the end of the thesis, to the creation of a monitor that meets the "Flash" irradiation requirements.
In the context of DIAMMONI, the diamond substrates are commercial diamonds. The instrumentation of the detectors is done at the LPSC. Different laboratories, members of the ANR-DIAMMONI consortium (LPSC SUBATECH ARRONAX) collaborate for their characterization: tests with alpha, beta sources at LPSC, in proton beams (68 MeV) and alpha (70 MeV) at SUBATECH-ARRONAX.
The PhD student will be in charge of this characterization work on the different sites, but will also have to model the beam monitors prototypes (active surface) in order to better understand their operation, and suggest improvements according to results obtained in data analysis, which also involves interacting with the technical services in charge of developments in instrumentation or electronics.
The candidate must therefore have skills in nuclear physics as well as knowledge in physics for medical applications and physics of detectors development, a willing for instrumentation, programming and analysis of physical data (C ++, PYTHON, ROOT, MATLAB) and simulation (TCAD, COMSOL, SRIM, GEANT4).
The project will benefit from the technical support of the electronic and instrumentation services of the LPSC as well as of the SUBATECH and ARRONAX laboratories in Nantes involved in the project.
Innovation and societal applications
This involves the development of detectors that break with the existing: the use of diamond detectors for a high-speed counting system and the associated reading electronics are particularly innovative. The proposed detection system will bring significant added value to the transfer of high dose rate flash radiotherapy to clinical trials.
The Grenoble Subatomic Physics and Cosmology Laboratory (LPSC) (http://lpsc.in2p3.fr) is a mixed research unit associating the CNRS-IN2P3, the University of Grenoble Alpes (UGA) and the Grenoble INP engineering school , for an average workforce of around 230 people.
The doctoral student will be assigned to the Nuclear Physics and Medical Applications team made up of 3 researchers, 2 teacher-researchers, 1 attached teacher-researcher, 1 attached research engineer, 4 doctoral students in 2021.
He (she) will be placed, at the LPSC, under the direct hierarchical authority of the head of the team D. Dauvergne
His /her thesis supervisor will be Dr Marie-Laure Gallin-Martel
He/ she will be co-supervised by Dr Charbel Koumeir, associated researcher at the SUBATECH laboratory (http://www-subatech.in2p3.fr/fr/)
Constraints and risks
The doctoral student will have to carry out experiments under beams, these particular constraints are governed by radiation protection measures and require not to present medical contraindications
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