Improved energy resolution of a cyclotron beam for RBS measurements

Chêne, Grégoire; Garnir, Henri-Pierre; Marchal, André; Mathis, François; Strivay, David

doi:10.1016/j.nimb.2008.02.077

Cited by 10 publications

(2 citation statements)

References 5 publications

(4 reference statements)

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“…A schematic representation of the experimental setup is given in figure 1(a). The entire detection chamber is movable and was mounted on two different particle accelerators: the ALTAIS accelerator installed at the LARN laboratory (UNamur) (Terwagne et al 2008) and the 20 MeV (proton) AVF (azimuthal varying field) cyclotron at Uliège (Chêne et al 2008). The proton beam diameter was set to 3 mm using an Al collimator.…”

Section: Methodsmentioning

confidence: 99%

Experimental measurements validate the use of the binary encounter approximation model to accurately compute proton induced dose and radiolysis enhancement from gold nanoparticles

et al. 2019

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In protontherapy, it has been suggested that nanoparticles of high-Z material like gold (GNP) could be used as radiosensitizers. The origin of this enhancement phenomenon for proton radiation is not yet well understood and additional mechanistic insights are required. Previous works have highlighted the good capabilities of TRAX to reproduce secondary electron emission from gold material. Therefore, TRAX cross sections obtained with the binary encounter approximation (BEA) model for proton ionization were implemented within Geant4 for gold material. Based on the TRAX cross sections, improved Geant4 simulations have been developed to investigate the energy deposition and radical species production around a spherical gold nanoparticle (5 and 10 nm in diameter) placed in a water volume during proton irradiation. Simulations were performed for incident 2 MeV proton. The dose enhancement factor and the radiolysis enhancement factor were quantified. Results obtained with the BEA model were compared with results obtained with condensed-history models. Experimental irradiation of 200 nm gold films were performed to validate the secondary electron emission reproduction capabilities of physical models used in Monte Carlo (MC) simulations. TRAX simulations reproduced the experimental backscattered electron energy spectrum from gold film with better agreement than Geant4. Results on gold film obtained with the BEA model enabled to estimate the electron emission from GNPs. Results obtained in our study tend to support that the use of the BEA discrete model leads to a significant increase of the dose in the near vicinity of GNPs (<20 nm), while condensed history models used in Geant4 seem to overestimate the dose and the number of chemical species for increasing distances from the GNP. Based on discrete BEA model results, no enhancement effect due to secondary electron emitted from the GNP is expected if the GNP is not in close proximity to key cellular functional elements (DNA, mitochondria…).

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Section: Methodsmentioning

confidence: 99%

Experimental measurements validate the use of the binary encounter approximation model to accurately compute proton induced dose and radiolysis enhancement from gold nanoparticles

et al. 2019

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“…The entire detection chamber is movable and was mounted and aligned on beam lines of two different proton accelerators: the ALTAIS accelerator at the LARN laboratory (UNamur) (Terwagne et al 2008) and the CGR-MEV 520 AVF (Azimuthal Varying Field) cyclotron of ULiège (Chêne et al 2008). The beam extracted from the ALTAIS and the AVF cyclotron and transferred to the detection chamber exhibits an energy resolution of 0.1% and 1% respectively.…”

Section: Methodsmentioning

confidence: 99%

Backscattered electron emission after proton impact on gold nanoparticles with and without polymer shell coating

Hespeels¹,

Heuskin²,

Tabarrant³

et al. 2019

Phys. Med. Biol.

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This work aims at measuring experimentally proton induced secondary electron energy spectra after interaction with gold nano particles (GNPs) and polymer-coated GNPs. Backscattered electron energy spectra were collected over a 0 to 1000 eV energy range using a retarding field analyzer (RFA). This paper presents the spectra obtained for proton beam energies of 0.5 and 2 MeV and diameter 2.5 and 3.8 nm GNPs. The spectra were also measured for 3.8 nm GNPs after 5 and 10 MeV proton irradiations. GNPs were deposited on a 100 nm carbon film. Each experimental spectrum was compared with dedicated simulations based on existing numerical models used in the TRAX and Geant4 Monte Carlo codes.For 100 nm carbon target, good agreement between experimental, TRAX and Geant4 simulation results can be observed.For 3.8 nm GNPs, the TRAX simulations reproduce with good agreement the electron energy spectra produced after 0.5, 2, 5 and 10 MeV proton irradiations, while Geant4 spectra display a lower secondary electron yield at low energy (<600 eV) for all the studied energies. This underestimation can mostly be explained by the 790 eV threshold applied in the condensed history model used by Geant4 which impacts the secondary electron energy distribution. Results obtained for carbon and gold targets highlight the impact of the secondary electron production threshold for proton ionization process considered in condensed history models.The experimental results demonstrate that the single interaction approach used in TRAX is adapted to reproduce secondary electron emission from GNPs. On the other hand, the standard electron generation threshold implement in G4BetheBlochModel and G4BraggModel condensedhistory models used in Geant4 is not adapted to reproduce low energy electron emission in gold targets.Finally, the results highlight that the GNP coating leads to a decrease of the electron yield and mostly affects low energy electrons (<500 eV) emitted from GNPs.

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High-Resolution Multispectral Scanning for Mesoscopic Investigation of Discoloration of Traditional Japanese Pigments

Toque¹,

Zhang

Wang

et al. 2015

Lecture Notes in Computer Science

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Improved energy resolution of a cyclotron beam for RBS measurements

Cited by 10 publications

References 5 publications

Experimental measurements validate the use of the binary encounter approximation model to accurately compute proton induced dose and radiolysis enhancement from gold nanoparticles

Experimental measurements validate the use of the binary encounter approximation model to accurately compute proton induced dose and radiolysis enhancement from gold nanoparticles

Backscattered electron emission after proton impact on gold nanoparticles with and without polymer shell coating

High-Resolution Multispectral Scanning for Mesoscopic Investigation of Discoloration of Traditional Japanese Pigments

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