119 research outputs found
Towards proton therapy and radiography at FAIR
No full textProtons having energies in the GeV range have been proposed as an alternative to Bragg-peak hadron therapy. This strategy reduces lateral scattering and overcomes uncertainties of particle range and relative biological effectiveness. GeV protons could additionally be used for targeting in image guided stereotactic radiosurgery. We experimentally demonstrated the potential of GeV protons for imaging of biological samples using E=0.8 GeV protons and the pRad setup at Los Alamos National Laboratory (LANL). In this setup, a system of magnetic lenses creates a point-to-point mapping from object to detector. This mapping compensates image blur due to lateral scattering inside the imaged (biological) object. We produced 2-dim proton radiographs of biological samples, an anthropomorphic phantom and performed simple dosimetry. High resolution tomographic reconstructions were derived from the 2-dim proton radiographs. Our experiment was performed within the framework of the PANTERA (Proton Therapy and Radiography) project. In the future, the proton microscope PRIOR (Proton Microscope for FAIR) located in the FAIR facility (Darmstadt), will focus on optimizing the technique for imaging of lesions implanted in animals and couple the irradiation with standard radiotherapy
Towards Proton Therapy and Radiography at FAIR
No full textProtons having energies in the GeV range have been proposed as an alternative to Bragg-peak hadron therapy. This strategy reduces lateral scattering and overcomes uncertainties of particle range and relative biological effectiveness. GeV protons could additionally be used for targeting in image guided stereotactic radiosurgery. We experimentally demonstrated the potential of GeV protons for imaging of biological samples using E=0.8 GeV protons and the pRad setup at Los Alamos National Laboratory (LANL). In this setup, a system of magnetic lenses creates a point-to-point mapping from object to detector. This mapping compensates image blur due to lateral scattering inside the imaged (biological) object. We produced 2-dim proton radiographs of biological samples, an anthropomorphic phantom and performed simple dosimetry. High resolution tomographic reconstructions were derived from the 2-dim proton radiographs. Our experiment was performed within the framework of the PANTERA (Proton Therapy and Radiography) project. In the future, the proton microscope PRIOR (Proton Microscope for FAIR) located in the FAIR facility (Darmstadt), will focus on optimizing the technique for imaging of lesions implanted in animals and couple the irradiation with standard radiotherapy
(Table 21) Chemical composition of material composing crustate growths and altered substratum of hydrothermally reworked hyaloclastite from the Krylov Seamount, Sample 1-18-D-54-2
No full text(Table 22) Elemental chemical composition of material composing crustate growths and altered substratum of hydrothermally reworked hyaloclastite from the Krylov Seamount, Sample 1-18-D-54-
First biological images with high-energy proton microscopy
No full textHigh-energy proton microscopy provides unique capabilities in penetrating radiography including the combination of high spatial resolution and field-of-view, dynamic range of density for measurements, and reconstructing density variations to less than 1% inside volumes and in situ environments. We have recently proposed to exploit this novel proton radiography technique for image-guided stereotactic particle radiosurgery. Results of a first test for imaging biological and tissue-equivalent targets with high-energy (800 MeV) proton microscopy are presented here. Although we used a proton microscope setup at ITEP (Moscow, Russia) optimized for fast dynamic experiments in material research, we could reach a spatial resolution of 150 μm with approximately 1010 protons per image. The potential of obtaining high-resolution online imaging of the target using a therapeutic proton beam in the GeV energy region suggests that high-energy proton microscopy may be used for image-guided proton radiosurgery. © 2012 Associazione Italiana di Fisica Medica
(Table 25) Elemental chemical composition of material composing crustate growths of Fe-Mn oxyhydroxides and altered substratum of hydrothermally phosphatized limestone from the Bezymyannaya-640 Seamount
No full text(Table 27) Elemental chemical composition of material composing crustate growths of Fe-Mn oxyhydroxides and altered substratum of hydrothermally phosphatized limestone from the Bezymyannaya-640 Seamount, Samples 1-38-D-124 and 1-39-D-12
High-energy proton imaging for biomedical applications
No full textThe charged particle community is looking for techniques exploiting proton interactions instead of X-ray absorption for creating images of human tissue. Due to multiple Coulomb scattering inside the measured object it has shown to be highly non-trivial to achieve sufficient spatial resolution. We present imaging of biological tissue with a proton microscope. This device relies on magnetic optics, distinguishing it from most published proton imaging methods. For these methods reducing the data acquisition time to a clinically acceptable level has turned out to be challenging. In a proton microscope, data acquisition and processing are much simpler. This device even allows imaging in real time. The primary medical application will be image guidance in proton radiosurgery. Proton images demonstrating the potential for this application are presented. Tomographic reconstructions are included to raise awareness of the possibility of high-resolution proton tomography using magneto-optics
APPA at FAIR: From fundamental to applied research
No full textFAIR with its intense beams of ions and antiprotons provides outstanding and worldwide unique experimental conditions for extreme matter research in atomic and plasma physics and for application oriented research in biophysics, medical physics and materials science. The associated research programs comprise interaction of matter with highest electromagnetic fields, properties of plasmas and of solid matter under extreme pressure, density, and temperature conditions, simulation of galactic cosmic radiation, research in nanoscience and charged particle radiotherapy. A broad variety of APPA-dedicated facilities including experimental stations, storage rings, and traps, equipped with most sophisticated instrumentation will allow the APPA community to tackle new challenges. The worldwide most intense source of slow antiprotons will expand the scope of APPA related research to the exciting field of antimatter
Radio Frequency and DC High Voltage Breakdown of High Pressure Helium, Argon, and Xenon
No full text[EN] Motivated by the possibility of guiding daughter ions from double beta decay events to single-ion sensors for barium tagging, the NEXT collaboration is developing a program of R&D to test radio frequency (RF) carpets for ion transport in high pressure xenon gas. This would require carpet functionality in regimes at higher pressures than have been previously reported, implying correspondingly larger electrode voltages than in existing systems. This mode of operation appears plausible for contemporary RF-carpet geometries due to the higher predicted breakdown strength of high pressure xenon relative to low pressure helium, the working medium in most existing RF carpet devices. In this paper we present the first measurements of the high voltage dielectric strength of xenon gas at high pressure and at the relevant RF frequencies for ion transport (in the 10MHz range), as well as new DC and RF measurements of the dielectric strengths of high pressure argon and helium gases at small gap sizes. We find breakdown voltages that are compatible with stable RF carpet operation given the gas, pressure, voltage, materials and geometry of interest.Woodruff, K.; Baeza-Rubio, J.; Huerta, D.; Jones, BJP.; Mcdonald, AD.; Norman, L.; Nygren, DR.... (2020). Radio Frequency and DC High Voltage Breakdown of High Pressure Helium, Argon, and Xenon. Journal of Instrumentation. 15(4):1-15. https://doi.org/10.1088/1748-0221/15/04/P04022S115154Dehmelt, H. G., & Major, F. G. (1962). Orientation of(He4)+Ions by Exchange Collisions with Cesium Atoms. Physical Review Letters, 8(5), 213-214. doi:10.1103/physrevlett.8.213Wada, M., Ishida, Y., Nakamura, T., Yamazaki, Y., Kambara, T., Ohyama, H., … Katayama, I. (2003). Slow RI-beams from projectile fragment separators. Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 204, 570-581. doi:10.1016/s0168-583x(02)02151-1Gehring, A. E., Brodeur, M., Bollen, G., Morrissey, D. J., & Schwarz, S. (2016). Research and development of ion surfing RF carpets for the cyclotron gas stopper at the NSCL. Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 376, 221-224. doi:10.1016/j.nimb.2016.02.012Ranjan, M., Purushothaman, S., Dickel, T., Geissel, H., Plass, W. R., Schäfer, D., … Dendooven, P. (2011). New stopping cell capabilities: RF carpet performance at high gas density and cryogenic operation. 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Physical Review C, 44(3), R931-R934. doi:10.1103/physrevc.44.r931Sinclair, D., Rollin, E., Smith, J., Mommers, A., Ackeran, N., Aharmin, B., … Breidenbach, M. (2011). Prospects for Barium Tagging in Gaseous Xenon. Journal of Physics: Conference Series, 309, 012005. doi:10.1088/1742-6596/309/1/012005Brunner, T., Fudenberg, D., Sabourov, A., Varentsov, V. L., Gratta, G., & Sinclair, D. (2013). A setup for Ba-ion extraction from high pressure Xe gas for double-beta decay studies with EXO. Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 317, 473-475. doi:10.1016/j.nimb.2013.05.086Twelker, K., Kravitz, S., Díez, M. M., Gratta, G., Fairbank, W., Albert, J. B., … Benitez-Medina, C. (2014). An apparatus to manipulate and identify individual Ba ions from bulk liquid Xe. Review of Scientific Instruments, 85(9), 095114. doi:10.1063/1.4895646Mong, B., Cook, S., Walton, T., Chambers, C., Craycraft, A., Benitez-Medina, C., … Auty, D. J. (2015). Spectroscopy of Ba andBa+deposits in solid xenon for barium tagging in nEXO. Physical Review A, 91(2). doi:10.1103/physreva.91.022505Brunner, T., Fudenberg, D., Varentsov, V., Sabourov, A., Gratta, G., Dilling, J., … Albert, J. B. (2015). An RF-only ion-funnel for extraction from high-pressure gases. International Journal of Mass Spectrometry, 379, 110-120. doi:10.1016/j.ijms.2015.01.003Nygren, D. R. (2016). Detection of the barium daughter in 136Xe →136Ba+2e− by in situ single-molecule fluorescence imaging. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 824, 2-5. doi:10.1016/j.nima.2015.11.038Jones, B. J. P., McDonald, A. D., & Nygren, D. R. (2016). Single molecule fluorescence imaging as a technique for barium tagging in neutrinoless double beta decay. Journal of Instrumentation, 11(12), P12011-P12011. doi:10.1088/1748-0221/11/12/p12011Byrnes, N., Foss, F. W., Jones, B. J. ., McDonald, A. D., Nygren, D. R., … Thapa, P. (2019). Progress toward Barium Tagging in High Pressure Xenon Gas with Single Molecule Fluorescence Imaging. Journal of Physics: Conference Series, 1312, 012001. doi:10.1088/1742-6596/1312/1/012001McDonald, A. D., Jones, B. J. P., Nygren, D. R., Adams, C., Álvarez, V., Azevedo, C. D. R., … Cárcel, S. (2018). Demonstration of Single-Barium-Ion Sensitivity for Neutrinoless Double-Beta Decay Using Single-Molecule Fluorescence Imaging. Physical Review Letters, 120(13). doi:10.1103/physrevlett.120.132504(2019). Imaging individual barium atoms in solid xenon for barium tagging in nEXO. Nature, 569(7755), 203-207. doi:10.1038/s41586-019-1169-4Thapa, P., Arnquist, I., Byrnes, N., Denisenko, A. A., Foss, F. W., Jones, B. J. P., … Woodruff, K. (2019). Barium Chemosensors with Dry-Phase Fluorescence for Neutrinoless Double Beta Decay. 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Quantifying Local and Mesoscale Drivers of the Urban Heat Island of Moscow with Reference and Crowdsourced Observations
No full textUrban climate features, such as the urban heat island (UHI), are determined by various factors characterizing the modifications of the surface by the built environment and human activity. These factors are often attributed to the local spatial scale (hundreds of meters up to several kilometers). Nowadays, more and more urban climate studies utilize the concept of the local climate zones (LCZs) as a proxy for urban climate heterogeneity. However, for modern megacities that extend to dozens of kilometers, it is reasonable to suggest a significant contribution of the larger-scale factors to the temperature and UHI climatology. In this study, we investigate the contribution of local-scale and mesoscale driving factors of the nocturnal canopy layer UHI of the Moscow megacity in Russia. The study is based on air temperature observations from a dense network consisting of around 80 reference and more than 1,500 crowdsourced citizen weather stations for a summer and a winter season. For the crowdsourcing data, an advanced quality control algorithm is proposed. Based on both types of data, we show that the spatial patterns of the UHI are shaped both by local-scale and mesoscale driving factors. The local drivers represent the surface features in the vicinity of a few hundred meters and can be described by the LCZ concept. The mesoscale drivers represent the influence of the surrounding urban areas in the vicinity of 2-20 km around a station, transformed by diffusion, and advection in the atmospheric boundary layer. The contribution of the mesoscale drivers is reflected in air temperature differences between similar LCZs in different parts of the megacity and in a dependence between the UHI intensity and the distance from the city center. Using high-resolution city-descriptive parameters and different statistical analysis, we quantified the contributions of the local- and mesoscale driving factors. For selected cases with a pronounced nocturnal UHI, their respective contributions are of similar magnitude. Our findings highlight the importance of taking both local- and mesoscale effects in urban climate studies for megacities into account. Furthermore, they underscore a need for an extension of the LCZ concept to take mesoscale settings of the urban environment into account
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