Cosmic rays have the potential to significantly affect the atmospheric composition by increasing the rate and changing the types of chemical reactions through ion production. The amount and states of ...ionization, and the spatial distribution of ions produced are still open questions for atmospheric models. To precisely estimate these quantities, it is necessary to simulate particle–molecule interactions, down to very low energies. Models enabling such simulations require interaction probabilities over a broad energy range and for all energetically allowed scattering processes.In this paper, we focus on electron interaction with the two most abundant molecules in the atmosphere, i.e., N2 and O2, as an initial step. A set of elastic and inelastic cross section models for electron transportation in oxygen and nitrogen molecules valid in the energy range 10 eV – 1 MeV, is presented. Comparison is made with available theoretical and experimental data and a reasonable good agreement is observed. Stopping power is calculated and compared with published data to assess the general consistency and reliability of our results. Good overall agreement is observed, with relative differences lower than 6% with the ESTAR database.
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•Optimization of emulsion polymerization to obtain P(MMA/AA)-89Y3+nanoparticles.•Composition of nanoparticles was confirmed by FTIR and SEM-EDX.•Μean particle diameter less than 30nm.
...Radiolabeled nanoparticles are promising tools in cancer diagnosis and therapy. Moreover, yttrium-90 (90Y) is a good candidate as suitable β− emitting radioisotope for a new approach to radio-guided surgery (RGS) proposed by some researchers of our group. In this work, we developed new composite nanoparticles, based on polymethylmethacrylate (PMMA), and poly(methylmethacrylate-co-acrylic acid), P(MMA/AA), embedded with yttrium ion (89Y3+), as a first step for the development of new 90Y3+ based nanocomposites. The composite nanoparticles were synthesised by emulsion polymerization technique, in the presence of potassium persulfate (KPS) as radical initiator, toluene as cosolvent, diethylenetriamine penta acetic acid dianhydride (DTPA) as chelating agent, using different MMA/89Y3+ molar ratios. The yttrium doped polymeric nanoparticles were characterized by means of FTIR spectroscopy, SEM-EDX, AFM, and DLS measurements. The influence of experimental parameters, such as cosolvent and reaction time, on morphology and dimension of composite nanoparticles was investigated, and monodispersed nanospheres with diameters from 20nm to 400nm were obtained. The composite material was purified and studied by means of DLS to confirm the colloid stability in water solution at different temperatures (25°C and 37°C) up to 3 weeks.
The use of C, He and O as beam particles in Particle Therapy (PT) treatments is getting more and more widespread as a consequence of the enhanced relative biological effectiveness and oxygen ...enhancement ratio of such projectiles with respect to protons. The advantages in the tumor control probability, related to the improved efficacy of ions, are calling for an online monitor of the dose release spatial distribution. Such technology is currently missing in PT treatments clinical routine. In this contribution the status of Z>1 ions PT treatments monitoring, exploiting the detection of either charged secondary particles or neutrons, is reviewed. While charged fragments can be used to provide an online feedback to the beam control system, by correlating their emission profile with the position of the Bragg peak, neutrons have to be monitored to improve the experimental description of the secondary radiation component that significantly contributes to an undesired and not negligible dose deposition far away from the tumor region, enhancing the risk of secondary malignancies development after the treatment. Two tracker detectors, employing scintillating fibers, are presented: the Dose Profiler designed for charged secondary fragments measurements and the MONDO tracker dedicated to the characterisation of the secondary fast and ultrafast neutron component, within the MONDO (MOnitor for Neutron Dose in hadrOntherapy) project.
In this paper we report the re-analysis of the data published in Piersanti et al (2014 Phys. Med. Biol. 59 1857) documenting the charged secondary particles production induced by the interaction of a ...220 MeV/u 12C ion beam impinging on a polymethyl methacrylate (PMMA) target, measured in 2012 at the GSI facility in Darmstadt (Germany). This re-analysis takes into account the inhomogeneous light response of the LYSO crystal in the experimental setup measured in a subsequent experiment (2014) performed in the Heidelberg Ion-Beam Therapy Center. A better description of the detector and re-calculation of the geometrical efficiencies have been implemented as well, based on an improved approach that accounts also for the energy dependence of the emission spectrum. The new analysis has little effect on the total secondary charged flux, but has an impact on the production yield and emission velocity distributions of the different particle species (protons, deuterons and tritons) at different angles with respect to the beam direction (60∘ and 90∘). All these observables indeed depend on the particle identification algorithms and hence on the LYSO detector energy response. The results of the data re-analysis presented here are intended to supersede and replace the results published in Piersanti et al (2014 Phys. Med. Biol. 59 1857).
Proton and carbon ion beams are used in the clinical practice for external radiotherapy treatments achieving, for selected indications, promising and superior clinical results with respect to x-ray ...based radiotherapy. Other ions, like 4He have recently been considered as projectiles in particle therapy centres and might represent a good compromise between the linear energy transfer and the radiobiological effectiveness of 12C ion and proton beams, allowing improved tumour control probability and minimising normal tissue complication probability. All the currently used p, 4He and 12C ion beams allow achieving sharp dose gradients on the boundary of the target volume, however the accurate dose delivery is sensitive to the patient positioning and to anatomical variations with respect to photon therapy. This requires beam range and/or dose release measurement during patient irradiation and therefore the development of dedicated monitoring techniques. All the proposed methods make use of the secondary radiation created by the beam interaction with the patient and, in particular, in the case of 12C ion beams are also able to exploit the significant charged radiation component. Measurements performed to characterise the charged secondary radiation created by 12C and 4He particle therapy beams are reported. Charged secondary yields, energy spectra and emission profiles produced in a poly-methyl methacrylate (PMMA) target by 4He and 12C beams of different therapeutic energies were measured at 60° and 90° with respect to the primary beam direction. The secondary yield of protons produced along the primary beam path in a PMMA target was obtained. The energy spectra of charged secondaries were obtained from time-of-flight information, whereas the emission profiles were reconstructed exploiting tracking detector information. The obtained measurements are in agreement with results reported in the literature and suggests the feasibility of range monitoring based on charged secondary particle detection: the implications for particle therapy monitoring applications are also discussed.
