2,328 research outputs found
Subchondral bone microstructural damage by increased remodelling aggravates experimental osteoarthritis preceded by osteoporosis
Performance of a Small Array of Imaging Air Cherenkov Telescopes sited in Australia
As TeV gamma-ray astronomy progresses into the era of the Cherenkov Telescope
Array (CTA), there is a desire for the capacity to instantaneously follow up on
transient phenomena and continuously monitor gamma-ray flux at energies above
eV. To this end, a worldwide network of Imaging Air Cherenkov
Telescopes (IACTs) is required to provide triggers for CTA observations and
complementary continuous monitoring. An IACT array sited in Australia would
contribute significant coverage of the Southern Hemisphere sky. Here, we
investigate the suitability of a small IACT array and how different design
factors influence its performance. Monte Carlo simulations were produced based
on the Small-Sized Telescope (SST) and Medium-Sized Telescope (MST) designs
from CTA. Angular resolution improved with larger baseline distances up to 277m
between telescopes, and energy thresholds were lower at 1000m altitude than at
0m. The 300 GeV energy threshold of MSTs proved more suitable for
observing transients than the 1.2 TeV threshold of SSTs. An array of four
MSTs at 1000m was estimated to give a 5.7 detection of an RS
Ophiuchi-like nova eruption from a 4-hour observation. We conclude that an
array of four MST-class IACTs at an Australian site would ideally complement
the capabilities of CTA.Comment: 10 pages, 13 figures, 2 tables, accepted for publication in PAS
Efficient proton acceleration from a 3 TW table-top laser interacting with submicrometric mass-produced solid targets
[EN] Thin layer membranes with controllable features and material arrangements are often used as target materials for laser driven particle accelerators. Reduced cost, large scale fabrication of such membranes with high reproducibility, and good stability are central for the efficient production of proton beams. These characteristics are of growing importance in the context of advanced laser light sources where increased repetition rates boost the need for consumable targets with design and properties adjusted to study the different phenomena arising in ultra-intense laser-plasma interaction. Wepresent the fabrication of sub-micrometric thin-layer gold or aluminum membranes in a silicon wafer frame by using nano/micro-electro-mechanical-system (N/MEMS) processing which are suitable for rapid patterning and machining of many samples at the same time and allowing for high-throughput production of targets for laser-driven acceleration. Obtained targets were tested for laserproton acceleration through the Target Normal Sheath Acceleration mechanism (TNSA) in a series of experiments carried out on a purpose-made table-top Ti:Sa running at 3 TW peak power and 10 Hz diode pump rate with a contrast over ASE of 10(8)The authors highly appreciate the collaboration of Radosys (Budapest) which provided CR-39 detector material, etching bath, and readout equipment. This project has been financed by the Spanish Ministry for Economy and Competitiveness within the Retos-Colaboracion 2015 initiative, ref. RTC-2015-3278-1. P Mur has received a grant of the Garantia Juvenil 2015 program. This work has made use of the Spanish ICTS Network MICRONANOFABS partially supported by MEINCOM.Zaffino, R.; Seimetz, M.; Ruiz-De La Cruz, A.; Sánchez, I.; Mur, P.; Quirión, D.; Bellido-Millán, PJ.... (2018). Efficient proton acceleration from a 3 TW table-top laser interacting with submicrometric mass-produced solid targets. Journal of Physics Communications. 2(4):1-6. https://doi.org/10.1088/2399-6528/aabc25S1624Borghesi, M., Campbell, D. H., Schiavi, A., Haines, M. G., Willi, O., MacKinnon, A. J., … Bulanov, S. (2002). Electric field detection in laser-plasma interaction experiments via the proton imaging technique. Physics of Plasmas, 9(5), 2214-2220. doi:10.1063/1.1459457Ledingham, K., Bolton, P., Shikazono, N., & Ma, C.-M. (2014). Towards Laser Driven Hadron Cancer Radiotherapy: A Review of Progress. Applied Sciences, 4(3), 402-443. doi:10.3390/app4030402Spindloe, C., Arthur, G., Hall, F., Tomlinson, S., Potter, R., Kar, S., … Tolley, M. K. (2016). High volume fabrication of laser targets using MEMS techniques. Journal of Physics: Conference Series, 713, 012002. doi:10.1088/1742-6596/713/1/012002Schomburg, W. K. (2011). Thin Films. RWTHedition, 9-20. doi:10.1007/978-3-642-19489-4_4Bellido, P., Lera, R., Seimetz, M., Cruz, A. R. la, Torres-Peirò, S., Galán, M., … Benlloch, J. M. (2017). Characterization of protons accelerated from a 3 TW table-top laser system. Journal of Instrumentation, 12(05), T05001-T05001. doi:10.1088/1748-0221/12/05/t05001Mayer, M. (1999). SIMNRA, a simulation program for the analysis of NRA, RBS and ERDA. AIP Conference Proceedings. doi:10.1063/1.59188Ceccotti, T., Lévy, A., Popescu, H., Réau, F., D’Oliveira, P., Monot, P., … Martin, P. (2007). Proton Acceleration with High-Intensity Ultrahigh-Contrast Laser Pulses. Physical Review Letters, 99(18). doi:10.1103/physrevlett.99.185002Dollar, F., Reed, S. A., Matsuoka, T., Bulanov, S. S., Chvykov, V., Kalintchenko, G., … Maksimchuk, A. (2013). High-intensity laser-driven proton acceleration enhancement from hydrogen containing ultrathin targets. Applied Physics Letters, 103(14), 141117. doi:10.1063/1.4824361Neely, D., Foster, P., Robinson, A., Lindau, F., Lundh, O., Persson, A., … McKenna, P. (2006). Enhanced proton beams from ultrathin targets driven by high contrast laser pulses. Applied Physics Letters, 89(2), 021502. doi:10.1063/1.2220011Green, J. S., Carroll, D. C., Brenner, C., Dromey, B., Foster, P. S., Kar, S., … Zepf, M. (2010). Enhanced proton flux in the MeV range by defocused laser irradiation. New Journal of Physics, 12(8), 085012. doi:10.1088/1367-2630/12/8/085012Giuffrida, L., Svensson, K., Psikal, J., Dalui, M., Ekerfelt, H., Gallardo Gonzalez, I., … Margarone, D. (2017). Manipulation of laser-accelerated proton beam profiles by nanostructured and microstructured targets. Physical Review Accelerators and Beams, 20(8). doi:10.1103/physrevaccelbeams.20.08130
Wafer-scale fabrication of target arrays for stable generation of proton beams by laser-plasma interaction
[EN] Large-scale fabrication of targets for laser-driven acceleration of ion beams is a prerequisite to establish suitable applications, and to keep up with the challenge of increasing repetition rate of currently available high-power lasers. Here we present manufacturing and test results of large arrays of solid targets for TNSA laser-driven ion acceleration. By applying micro-electro-mechanical-system (MEMS) based methods allowing for parallel processing of thousands of targets on a single Si wafer, sub-micrometric, thin-layer metallic membranes were fabricated by combining photolithography, physical and chemical vapor deposition, selective etching, and Si micromachining. These structures were characterized by using optical and atomic force microscopy. Their performance for the production of laser-driven proton beams was tested on a purpose-made table-top Ti:Sapphire laser system running at 3 TW peak power with a contrast over ASE of 108. We have performed several test series achieving maximum proton energy values around 2 MeV.This work has made use of the Spanish ICTS Network MICRONANOFABS partially supported by MEINCOM. This project has been financed by the Spanish Ministry for Economy and Competitiveness within the Retos- Colaboración 2015 initiative, ref. RTC-2015-3278-1. P. Mur has received a grant of the Garantía Juvenil 2015 program.Zaffino, R.; Seimetz, M.; Ruiz-De La Cruz, A.; Sánchez, I.; Mur, P.; Bellido-Millán, PJ.; Lera, R.... (2018). Wafer-scale fabrication of target arrays for stable generation of proton beams by laser-plasma interaction. Journal of Physics: Conference Series (Online). 1079. https://doi.org/10.1088/1742-6596/1079/1/012007S0120071079Abedi, S., Dorranian, D., Abari, M. E., & Shokri, B. (2011). Relativistic effects in the interaction of high intensity ultra-short laser pulse with collisional underdense plasma. Physics of Plasmas, 18(9), 093108. doi:10.1063/1.3633529Antici, P., Fuchs, J., d’ Humières, E., Lefebvre, E., Borghesi, M., Brambrink, E., … Pépin, H. (2007). Energetic protons generated by ultrahigh contrast laser pulses interacting with ultrathin targets. Physics of Plasmas, 14(3), 030701. doi:10.1063/1.2480610Ceccotti, T., Lévy, A., Popescu, H., Réau, F., D’Oliveira, P., Monot, P., … Martin, P. (2007). Proton Acceleration with High-Intensity Ultrahigh-Contrast Laser Pulses. Physical Review Letters, 99(18). doi:10.1103/physrevlett.99.18500
Development of a few TW Ti:Sa laser system at 100 Hz for proton acceleration
[EN] We report the development of a table-top high peak power Titanium:Sapphire (Ti:Sa) CPA laser working at 100 Hz capable of delivering 205 mJ, 55 fs pulses. Every amplification stage is pumped by Nd-doped solid-state lasers and fully powered by diodes. Thermal effects in the Ti:Sa amplifiers are compensated passively with optics. This system is intended to be used for proton acceleration experiments at high repetition rates.Centro para el Desarrollo Tecnológico Industrial (CDTI, Spain) within the INNPRONTA program, Grant no. IPT-20111027.Lera, R.; Bellido-Millán, PJ.; Sánchez, I.; Mur, P.; Seimetz, M.; Benlloch Baviera, JM.; Roso, L.... (2019). Development of a few TW Ti:Sa laser system at 100 Hz for proton acceleration. Applied Physics B. 125(1):1-8. https://doi.org/10.1007/s00340-018-7113-8S181251P. Zeitoun, G. Faivre, S. Sebban, T. Mocek, A. Hallou, M. Fajardo, D. Aubert, P. Balcou, F. Burgy, D. Douillet, S. Kazamias, G. de Lachèze-Murel, T. Lefrou, S. le Pape, P. Mercère, H. Merdji, A.S. Morlens, J.P. Rousseau, C. Valentin, Nature 431(7007), 426–429 (2004)V. Malka, S. Fritzler, E. Lefebvre, M.-M. Aleonard, F. Burgy, J.-P. Chambaret, J.-F. Chemin, K. Krushelnick, G. Malka, S.P.D. Mangles, Z. Najmudin, M. Pittman, J.-P. Rousseau, J.-N. Scheurer, B. Walton, A.E. Dangor, Science 298(5598), 1596–1600 (2002)H. Daido, M. Nishiuchi, A.S. Pirozhkov, Rep. Progress Phys. 75(5), 056401 (2012)A. Macchi, M. Borghesi, M. Passoni, Rev. Mod. Phys. 85, 751–793 (2013)T. Tajima, J.M. Dawson, Phys. Rev. Lett. 43, 267–270 (1979)M. Noaman-ul Haq, H. Ahmed, T. Sokollik, L. Yu, Z. Liu, X. Yuan, F. Yuan, M. Mirzaie, X. Ge, L. Chen, J. Zhang, Phys. Rev. Accel. Beams 20, 041301 (2017)D. Strickland, G. Mourou, Opt. Commun. 53(3), 219–221 (1985)G. Cheriaux, B. Walker, L.F. Dimauro, P. Rousseau, F. Salin, J.P. Chambaret, Opt. Lett. 21(6), 414–416 (1996)P. Tournois, Opt. Commun. 140(4), 245–249 (1997)R. Soulard, A. Brignon, S. Raby, E. Durand, R. Moncorgé, Appl. Phys. B 106(2), 295–300 (2012)J. Liu, L. Ge, L. Feng, H. Jiang, H. Su, T. Zhou, J. Wang, Q. Gao, J. Li, Chin. Opt. Lett. 14(5), 051404 (2016)A. Maleki, M.K. Tehrani, H. Saghafifar, M.H.M. Dindarlu, H. Ebadian, Laser Phys. 26(2), 025003 (2016)R. Lera, F. Valle-Brozas, S. Torres-Peiró, A.R. de-la Cruz, M. Galán, P. Bellido, M. Seimetz, J.M. Benlloch, L. Roso, Appl. Opt. 55(33), 9573–9576 (2016)R. Lausten, P. Balling, J. Opt. Soc. Am. B 20(7), 1479–1485 (2003)I. Nam, M. Kim, T.H. Lee, S.W. Lee, H. Suk, Curr. Appl. Phys. 15(4), 468–472 (2015)E. Treacy, IEEE J. Quantum Electron. 5(9), 454–458 (1969)A. Trisorio, S. Grabielle, M. Divall, N. Forget, C.P. Hauri, Opt. Lett. 37(14), 2892–2894 (2012)Y.-H. Cha, Y.-W. Lee, S.M. Nam, J.M. Han, Y.J. Rhee, B.D. Yoo, B.C. Lee, Y.U. Jeong, Appl. Opt. 46(28), 6854–6858 (2007)P. Bellido, R. Lera, M. Seimetz, A.R. de la Cruz, S. Torres-Peiró, M. Galán, P. Mur, I. Sánchez, R. Zaffino, L. Vidal, A. Soriano, S. Sánchez, F. Sánchez, M. Rodríguez-Álvarez, J. Rigla, L. Moliner, A. Iborra, L. Hernández, D. Grau-Ruiz, A. González, J. García-Garrigos, E. Díaz-Caballero, P. Conde, A. Aguilar, L. Roso, J. Benlloch, J. Instrum. 12(05), T05001 (2017
Inflating in a Better Racetrack
We present a new version of our racetrack inflation scenario which, unlike
our original proposal, is based on an explicit compactification of type IIB
string theory: the Calabi-Yau manifold P^4_[1,1,1,6,9]. The axion-dilaton and
all complex structure moduli are stabilized by fluxes. The remaining 2 Kahler
moduli are stabilized by a nonperturbative superpotential, which has been
explicitly computed. For this model we identify situations for which a linear
combination of the axionic parts of the two Kahler moduli acts as an inflaton.
As in our previous scenario, inflation begins at a saddle point of the scalar
potential and proceeds as an eternal topological inflation. For a certain range
of inflationary parameters, we obtain the COBE-normalized spectrum of metric
perturbations and an inflationary scale of M = 3 x 10^{14} GeV. We discuss
possible changes of parameters of our model and argue that anthropic
considerations favor those parameters that lead to a nearly flat spectrum of
inflationary perturbations, which in our case is characterized by the spectral
index n_s = 0.95.Comment: 20 pages, 7 figures. Brief discussion on the non-gaussianity of this
model, one more figure of the field trajectories added as well as other minor
changes to the tex
Forensic Technologies in Music Copyright
The essay explores some recent controversies in British music copyright through the evolving technologies used to perform or play music in the courtroom. While the conceptual tension between cases has caused doctrinal anxiety about the effect of popular music in copyright, the essay contends that the recent stream of music copyright cases can be considered from a historical perspective, taking into account the tools, materials and experts as they featured in court. In doing so, the essay connects a history of legal expertise to the emergence of new technologies while arguing that legal knowledge about music copyright was, in fact, stabilised in the courtroom
Transferable Classical Force Field for Pure and Mixed Metal Halide Perovskites Parameterized from First-Principles
Identificador de proyecto: PCI2019-111839-2 (SCALEUP)Many key features in photovoltaic perovskites occur
in relatively long time scales and involve mixed compositions. This
requires realistic but also numerically simple models. In this work
we present a transferable classical force field to describe the mixed
hybrid perovskite MAxFA1¿xPb(BryI1¿y)3 for variable composition
(¿x, y ¿ [0, 1]). The model includes Lennard-Jones and
Buckingham potentials to describe the interactions between the
atoms of the inorganic lattice and the organic molecule, and the
AMBER model to describe intramolecular atomic interactions.
Most of the parameters of the force field have been obtained by
means of a genetic algorithm previously developed to parametrize
the CsPb(BrxI1¿x)3 perovskite (Balestra et al. J. Mater. Chem. A.
2020, DOI: 10.1039/d0ta03200j). The algorithm finds the best parameter set that simultaneously fits the DFT energies obtained for
several crystalline structures with moderate degrees of distortion with respect to the equilibrium configuration. The resulting model
reproduces correctly the XRD patterns, the expansion of the lattice upon I/Br substitution, and the thermal expansion coefficients.
We use the model to run classical molecular dynamics simulations with up to 8600 atoms and simulation times of up to 40 ns. From
the simulations we have extracted the ion diffusion coefficient of the pure and mixed perovskites, presenting for the first time these
values obtained by a fully dynamical method using a transferable model fitted to first-principles calculations. The values here
reported can be considered as the theoretical upper limit, that is, without grain boundaries or other defects, for ion migration
dynamics induced by halide vacancies in photovoltaic perovskite devices under operational conditions.TU/
Statistical moments of scintillation light distribution analysis with dSiPMs and monolithic crystals
[Otros] Monolithic scintillation crystals offer the possibility to preserve the scintillation light distribution, specially when black painted. Furthermore, the statistical moments of that distribution can provide accurate information about the three spatial components. Nevertheless, for monolithic crystal the moments estimation has an associated error due to the symmetry truncation of the light distribution towards the crystal borders. For the 2-D impact coordinates determination, this error is called compression as it is accentuated near the edges. The computation of all centered moments is, therefore, affected by this error. Digital SiPMs (dSiPMs) can offer complete information about the light distribution, since all cells are purely digital detectors, so that other ways to obtain ¿-impact coordinates can be performed. In this work, a comparison between the statistical moments analysis and an alternative fitting the light distribution for each event to a theoretical distribution has been made. With the fitted approach, compression is avoided and an approximately constant spatial resolution is obtained for the entire photodetection area. Moreover, DOI information is improved and preserved all over the crystal.This work was supported by the Spanish Plan Nacional de Investigacion Científica, Desarrollo e Innovación Tecnologica (I+D+I) under Grant No. FIS2010-21216-CO2-01 and Valencian Local Government under Grants PROMETEOII/2013/010 and ISIC 2011/013Conde, P.; González Martínez, AJ.; Hernández, L.; Bellido, P.; Crespo, E.; Iborra, A.; Moliner, L.... (2013). Statistical moments of scintillation light distribution analysis with dSiPMs and monolithic crystals. IEEE. 10-13. https://doi.org/10.1109/NSSMIC.2013.6829086S101
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