Présentation au Séminaire Jeunes Docteurs du GDR MI2B le 1er février 2021
A diamond beam-tagging hodoscope for online ion verification in hadrontherapy by means of
time-of-flight enhanced Prompt-Gamma detection
Hadrontherapy could benefit from an online ion range monitoring system. First, it would allow to
reduce ion range specific security margins currently set in the treatment planning. It could also enable
to detect discrepancies between the planned and the actual ion range during a treatment session.
Several groups are currently developing online ion range verification techniques and many of them are
based on secondary particle detection. Among them, prompt-gamma photons (PG) emission results
from inelastic nuclear interactions occurring along the ion pathway and their emission profile is thus
spatially correlated to the ion range.
The CLaRyS national collaboration is developing such PG-based monitoring systems. The originality
in CLaRyS’ approach consists in adding a beam-tagging hodoscope to the detection system which
provides spatial and temporal information on incoming ions. Combining an overall 100 ps (σ)
resolution on the ion+PG time-of-flight and single ion regime, the efficiency and sensitivity of PGbased
verification systems could be notably improved. To fulfill these requirements, the hodoscope
should be fast, radiation-hard and sensitive to single ions. In this context, diamond-based hodoscope
demonstraters are currently under development.
As synthetic diamond is available in various crystalline qualities and sizes, this work was highly
focused on the characterization carried out on commercially available samples to highlight the best
hodoscope candidate. The presentation will review the different lab and beam tests done at lab and in
different particle beam configurations with Chemical Vapor Deposition (CVD) diamond samples. Their
single ion detection efficiency, time resolution and counting capabilities were measured. Their spatial
response was also assessed with a X-ray micro-beam. The first double-sided strip prototypes,
developed during this thesis, will also be introduced. The presentation will be concluded by a brief
presentation of larger area diamond hodoscope demonstrators which are currently under construction
with dedicated front-end electronics and acquisition system.