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Purpose: The purpose of this study was to experimentally assess the possibility to monitor carbon ion range variations—due to tumor shift and/or elongation or shrinking—using prompt-gamma (PG) emission with inhomogeneous phantoms. Such a study is related to the development of PG monitoring techniques to be used in a carbon ion therapy context. Methods: A 95 MeV/u carbon ion beam was used to irradiate phantoms with a variable density along the ion path to mimic the presence of bone and lung in homogeneous humanlike tissue. PG profiles were obtained after a longitudinal scan of the phantoms. A setup comprising a narrow single-slit collimator and two detectors placed at 90° with respect to the beam axis was used. The time of flight technique was applied to allow the selection between PG and background events. Results: Using the positions at 50% entrance and 50% falloff of the PG profiles, a quantity called prompt-gamma profile length (PGPL) is defined. It is possible to observe shifts in the PGPL when there are absolute ion range shifts as small as 1–2 mm. Quantitatively, for an ion range shift of −1.33 ± 0.46 mm (insertion of a Teflon slab), a PGPL difference of −1.93 ± 0.58 mm and −1.84 ± 1.27 mm is obtained using a BaF2 and a NaI(Tl) detector, respectively. In turn, when an ion range shift of 4.59 ± 0.42 mm (insertion of a lung-equivalent material slab) is considered, the difference is of 4.10 ± 0.54 and 4.39 ± 0.80 mm for the same detectors. Conclusions: Herein, experimental evidence of the usefulness of employing PG to monitor carbon ion range using inhomogeneous phantoms is presented. Considering the homogeneous phantom as reference, the results show that the information provided by the PG emission allows for detecting ion range shifts as small as 1–2 mm. When considering the expected PG emission from an energy slice in a carbon ion therapy scenario, the experimental setup would allow to retrieve the same PGPL as the high statistics of the full experimental dataset in 58% of the times. However, this success rate increases to 93% when using a better optimized setup by means of Monte Carlo simulations.

The current diversity and inconsistency among published quadrupole moments calls for a thorough evaluation of the available data. In this work, a review of the ground-state Q-moments of the oxygen to calcium isotopes is presented, resulting in a revised database of 43 quadrupole moments. For every π (sd) isotope chain, the quadrupole moments are expressed relative to one reference isotope. This common reference rules out the existing arbitrariness and provides a reliable basis for future measurements and theoretical studies. In addition, the evaluated quadrupole-moment values are compared to shell-model calculations, obtained with different effective interactions in the sd and sdpf model spaces and using the standard effective charges e p = 1.3 e and e n = 0.5 e . The discrepancy between theory and experiment, observed for particular isotopes and isotope chains, calls for further fundamental research.

International audience; The goal of this study is to tune the design of the absorber detector of a Compton camera for prompt γ-ray imaging during ion beam therapy. The response of the Compton camera to a photon point source with a realistic energy spectrum (corresponding to the prompt γ-ray spectrum emitted during the carbon irradiation of a water phantom) is studied by means of Geant4 simulations. Our Compton camera consists of a stack of 2 mm thick silicon strip detectors as a scatter detector and of a scintillator plate as an absorber detector. Four scintillators are considered: LYSO, NaI, LaBr3 and BGO. LYSO and BGO appear as the most suitable materials, due to their high photo-electric cross-sections, which leads to a high percentage of fully absorbed photons. Depth-of-interaction measurements are shown to have limited influence on the spatial resolution of the camera. In our case, the thickness which gives the best compromise between a high percentage of photons that are fully absorbed and a low parallax error is about 4 cm for the LYSO detector and 4.5 cm for the BGO detector. The influence of the width of the absorber detector on the spatial resolution is not very pronounced as long as it is lower than 30 cm.

A new β -NMR / β -NQR setup is developed to study nuclear magnetic dipole moments and electric quadrupole moments at the LISE fragment separator at GANIL. Two key elements make the new design very powerful: the homogeneous magnet and the strong radio-frequency amplifier. The combination of both makes it possible to examine a broad spectrum of magnetic dipole and electric quadrupole moments. Several factors have an influence on the detection efficiency and on the sensitivity of the setup to observe a resonant change in the β -asymmetry : the thickness and the tilting angle of the implantation crystal, the material in the vacuum chamber, the applied magnetic field and the Q β -value of the decaying nuclei. A detailed study of these effects is made using a dedicated GEANT4 Monte Carlo simulation code.

The purpose of this study was to experimentally assess the possibility to monitor carbon ion range variations--due to tumor shift and/or elongation or shrinking--using prompt-gamma (PG) emission with inhomogeneous phantoms. Such a study is related to the development of PG monitoring techniques to be used in a carbon ion therapy context.A 95 MeV/u carbon ion beam was used to irradiate phantoms with a variable density along the ion path to mimic the presence of bone and lung in homogeneous humanlike tissue. PG profiles were obtained after a longitudinal scan of the phantoms. A setup comprising a narrow single-slit collimator and two detectors placed at 90° with respect to the beam axis was used. The time of flight technique was applied to allow the selection between PG and background events.Using the positions at 50% entrance and 50% falloff of the PG profiles, a quantity called prompt-gamma profile length (PGPL) is defined. It is possible to observe shifts in the PGPL when there are absolute ion range shifts as small as 1-2 mm. Quantitatively, for an ion range shift of -1.33 ± 0.46 mm (insertion of a Teflon slab), a PGPL difference of -1.93 ± 0.58 mm and -1.84 ± 1.27 mm is obtained using a BaF2 and a NaI(Tl) detector, respectively. In turn, when an ion range shift of 4.59 ± 0.42 mm (insertion of a lung-equivalent material slab) is considered, the difference is of 4.10 ± 0.54 and 4.39 ± 0.80 mm for the same detectors.Herein, experimental evidence of the usefulness of employing PG to monitor carbon ion range using inhomogeneous phantoms is presented. Considering the homogeneous phantom as reference, the results show that the information provided by the PG emission allows for detecting ion range shifts as small as 1-2 mm. When considering the expected PG emission from an energy slice in a carbon ion therapy scenario, the experimental setup would allow to retrieve the same PGPL as the high statistics of the full experimental dataset in 58% of the times. However, this success rate increases to 93% when using a better optimized setup by means of Monte Carlo simulations.

We present the results of combined laser spectroscopy and nuclear magnetic resonance studies of 21Mg. The nuclear ground-state spin was measured to be I = 5 / 2 with a magnetic moment of μ = − 0.983 ( 7 ) μ N . The isoscalar magnetic moment of the mirror pair ( F 21 , Mg 21 ) is evaluated and compared to the extreme single-particle prediction and to nuclear shell-model calculations. We determine an isoscalar spin expectation value of 〈 σ 〉 = 1.15 ( 2 ) , which is significantly greater than the empirical limit of unity given by the Schmidt values of the magnetic moments. Shell-model calculations taking into account isospin non-conserving effects, are in agreement with our experimental results.