The Experts below are selected from a list of 267 Experts worldwide ranked by ideXlab platform
L De Nardo - One of the best experts on this subject based on the ideXlab platform.
-
track structure of Light Ions experiments and simulatIons
New Journal of Physics, 2012Co-Authors: V Conte, P Colautti, B Grosswendt, D Moro, L De NardoAbstract:To study the track structure of Light Ions, a measuring device has been developed at the Legnaro National Laboratory of INFN, which can be used to investigate separately the penumbra region of particle tracks and the track- core region, which is a few nanometres in diameter. The device is based on single-electron counting techniques by means of a gas detector; it simulates a 'nanometre-sized' biological volume of about 20nm in diameter that can be moved with respect to a narrow particle beam to measure the ionization- cluster-size distributIons caused within the target volume by the passage of single primary particles, as a function of the impact parameter. To investigate the ionization-cluster-size formation caused by primary particles of medical interest when they penetrate through or pass by the target volume at a specified impact parameter, measurements and Monte Carlo simulatIons were performed for 20MeV protons, 16MeV deuterons, 48MeV 6 Li-Ions, 26.7MeV 7 Li-Ions and 96MeV 12 C-Ions. The detailed analysis of the resulting distributIons showed that in the track-core region their shape is mainly determined by the mean free ionization path length of the primary particles, whereas in the penumbra region the shape of the distributIons is almost independent of the impact parameter, and also of the particle type and velocity.
V A Yerokhin - One of the best experts on this subject based on the ideXlab platform.
-
g factor of Light Ions for an improved determination of the fine structure constant
Physical Review Letters, 2016Co-Authors: V A Yerokhin, E Berseneva, Zoltan Harman, I I Tupitsyn, Christoph H KeitelAbstract:: A weighted difference of the g factors of the H- and Li-like Ions of the same element is theoretically studied and optimized in order to maximize the cancellation of nuclear effects between the two charge states. We show that this weighted difference and its combination for two different elements can be used to extract a value for the fine-structure constant from near-future bound-electron g factor experiments with an accuracy competitive with or better than the present literature value.
Robert D Stewart - One of the best experts on this subject based on the ideXlab platform.
-
rapid mcnp simulation of dna double strand break dsb relative biological effectiveness rbe for photons neutrons and Light Ions
Physics in Medicine and Biology, 2015Co-Authors: Robert D Stewart, Seth Streitmatter, David C Argento, C Kirkby, John T Goorley, Greg Moffitt, Tatjana Jevremovic, George A SandisonAbstract:: To account for particle interactIons in the extracellular (physical) environment, information from the cell-level Monte Carlo damage simulation (MCDS) for DNA double strand break (DSB) induction has been integrated into the general purpose Monte Carlo N-particle (MCNP) radiation transport code system. The effort to integrate these models is motivated by the need for a computationally efficient model to accurately predict particle relative biological effectiveness (RBE) in cell cultures and in vivo. To illustrate the approach and highLight the impact of the larger scale physical environment (e.g. establishing charged particle equilibrium), we examined the RBE for DSB induction (RBEDSB) of x-rays, (137)Cs γ-rays, neutrons and Light Ions relative to γ-rays from (60)Co in monolayer cell cultures at various depths in water. Under normoxic conditIons, we found that (137)Cs γ-rays are about 1.7% more effective at creating DSB than γ-rays from (60)Co (RBEDSB = 1.017) whereas 60-250 kV x-rays are 1.1 to 1.25 times more efficient at creating DSB than (60)Co. Under anoxic conditIons, kV x-rays may have an RBEDSB up to 1.51 times as large as (60)Co γ-rays. Fission neutrons passing through monolayer cell cultures have an RBEDSB that ranges from 2.6 to 3.0 in normoxic cells, but may be as large as 9.93 for anoxic cells. For proton pencil beams, Monte Carlo simulatIons suggest an RBEDSB of about 1.2 at the tip of the Bragg peak and up to 1.6 a few mm beyond the Bragg peak. Bragg peak RBEDSB increases with decreasing oxygen concentration, which may create opportunities to apply proton dose painting to help address tumor hypoxia. Modeling of the particle RBE for DSB induction across multiple physical and biological scales has the potential to aid in the interpretation of laboratory experiments and provide useful information to advance the safety and effectiveness of hadron therapy in the treatment of cancer.
-
fast monte carlo simulation of dna damage formed by electrons and Light Ions
Physics in Medicine and Biology, 2006Co-Authors: Vladimir A Semenenko, Robert D StewartAbstract:The passage of ionizing radiation through living organisms initiates physical and chemical processes that create clusters of damaged nucleotides within one or two turns of the DNA. These clusters are widely considered an important initiating event for the induction of other biological endpoints, including cell killing and neoplastic transformation. Monte Carlo simulatIons of the DNA damage formation process are a useful adjunct to experiments because they provide additional information about the spatial configuration of damage within a cluster. In this paper, the fast Monte Carlo damage simulation (MCDS) algorithm is re-parameterized so that yields of double-strand breaks, single-strand breaks and sites of multiple base damage can be simulated for electrons, protons and α particles with kinetic energies on the order of GeV. The MCDS algorithm provides a useful, quasi-phenomenological scheme to interpolate damage yields from computationally expensive, but more detailed, track-structure simulatIons. The predicted characteristics of various classes of damage produced by electrons, protons and α particles, such as average number of lesIons per DNA damage cluster and cluster length in base pairs, are presented. A study examining the effects on damage complexity of an extrinsic free radical scavenger, dimethyl sulfoxide, is also presented. The reported studies provide new information that will aid efforts to characterize the relative biological effectiveness of high-energy protons and other Light Ions, which are sometimes used in particle therapy for the treatment of cancer.
C A Jenkins - One of the best experts on this subject based on the ideXlab platform.
-
improvement of structural electronic and magnetic properties of co2mnsi thin films by he irradiation
Applied Physics Letters, 2009Co-Authors: O Gaier, Jaroslav Hamrle, B Hillebrands, M Kallmayer, P Porsch, G Schonhense, H J Elmers, J Fassbender, A Gloskovskii, C A JenkinsAbstract:The influence of 30 keV He+ ion irradiation on structural, electronic, and magnetic properties of Co2MnSi thin films with a partial B2 order was investigated. It was found that room temperature irradiation with Light Ions can improve the local chemical order. This provokes changes of the electronic structure and element-specific magnetization toward the bulk properties of a well-ordered Co2MnSi Heusler compound.
V Conte - One of the best experts on this subject based on the ideXlab platform.
-
track structure of Light Ions experiments and simulatIons
New Journal of Physics, 2012Co-Authors: V Conte, P Colautti, B Grosswendt, D Moro, L De NardoAbstract:To study the track structure of Light Ions, a measuring device has been developed at the Legnaro National Laboratory of INFN, which can be used to investigate separately the penumbra region of particle tracks and the track- core region, which is a few nanometres in diameter. The device is based on single-electron counting techniques by means of a gas detector; it simulates a 'nanometre-sized' biological volume of about 20nm in diameter that can be moved with respect to a narrow particle beam to measure the ionization- cluster-size distributIons caused within the target volume by the passage of single primary particles, as a function of the impact parameter. To investigate the ionization-cluster-size formation caused by primary particles of medical interest when they penetrate through or pass by the target volume at a specified impact parameter, measurements and Monte Carlo simulatIons were performed for 20MeV protons, 16MeV deuterons, 48MeV 6 Li-Ions, 26.7MeV 7 Li-Ions and 96MeV 12 C-Ions. The detailed analysis of the resulting distributIons showed that in the track-core region their shape is mainly determined by the mean free ionization path length of the primary particles, whereas in the penumbra region the shape of the distributIons is almost independent of the impact parameter, and also of the particle type and velocity.