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154 results on '"Pavez, Cristian"'

1. Ambient neutron dosimetry in high energy and pulsed neutron fields

Author

Tarifeno-Saldivia, Ariel, Calvino, Francisco, De Blas, Alfredo, Brusasco, Benedetta, Casanovas-Hoste, Adria, Cives, Ana M., Cortes, Guillem, Garcia, Roger, Molina, Francisco, Mont-Geli, Nil, Pallas, Max, and Pavez, Cristian

Subjects
Physics - Instrumentation and Detectors, Physics - Medical Physics
Abstract

The status of the LINrem project is presented, focusing on the development of innovative neutron dosimeters with enhanced energy sensitivity, time resolution, and portability. Designed to meet the technical demands of radiation protection in modern particle and nuclear facilities, these dosimeters are discussed in detail. Results from experimental campaigns showcasing their efficacy in pulsed fields generated by fusion plasmas and high-intensity pulsed lasers are presented. Additionally, prospects and future plans for the LINrem project are outlined., Comment: Preprint submitted to Radiation Physics and Chemistry

Published
2024

2. A derivation of the kappa distribution in non-equilibrium, steady-state plasmas

Author

Davis, Sergio, Avaria, Gonzalo, Bora, Biswajit, Jain, Jalaj, Moreno, José, Pavez, Cristian, and Soto, Leopoldo

Subjects
Condensed Matter - Statistical Mechanics, Physics - Plasma Physics
Abstract

Kappa-distributed velocities in plasmas are common in a wide variety of settings, from low-density to high-density plasmas, and appear in both space and laboratory plasmas. Despite being widely used as a model, the origin of the kappa distribution remains, to this day, unclear. For instance, deviations from the Maxwell-Boltzmann distribution are sometimes regarded as a signature of the non-additivity of the thermodynamic entropy, although there are alternative frameworks such as superstatistics where such an assumption is not needed. In this work we recover the kappa distribution for particle velocities in a non-equilibrium, steady-state plasma from the theory of superstatistics, assuming only a single requirement on the dependence between the kinetic energy of a test particle and that of its immediate environment. Most importantly, unlike previous derivations based on superstatistics, we do not make any assumption about temperature or its statistical distribution, instead obtaining them from the requirement on kinetic energies. Our results suggest that a description of kappa-distributed plasma is simpler in terms of features of the inverse temperature distribution rather than the traditional parameters $\kappa$ and the thermal velocity $v_{\text{th}}$.

Published
2023

4. Single-particle velocity distributions of collisionless, steady-state plasmas must follow Superstatistics

Author

Davis, Sergio, Avaria, Gonzalo, Bora, Biswajit, Jain, Jalaj, Moreno, José, Pavez, Cristian, and Soto, Leopoldo

Subjects
Condensed Matter - Statistical Mechanics, Physics - Plasma Physics
Abstract

The correct modelling of velocity distribution functions for particles in steady-state plasmas is a central element in the study of nuclear fusion and also in the description of space plasmas. In this work, a statistical mechanical formalism for the description of collisionless plasmas in a steady state is presented, based solely on the application of the rules of probability and not relying on the concept of entropy. Beck and Cohen's superstatistical framework is recovered as a limiting case, and a "microscopic" definition of inverse temperature $\beta$ is given. Non-extensivity is not invoked a priori but enters the picture only through the analysis of correlations between parts of the system.

Published
2019
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6. On the Use of UHF Sensors in the Detection and Characterization of Pulsed Plasma Discharges

Author

Orellana, Luis, Ardila, Jorge, Avaria, Gonzalo, Cevallos, Benjamín, Pavez, Cristian, Schurch, Roger, Soto, Leopoldo, Angrisani, Leopoldo, Series Editor, Arteaga, Marco, Series Editor, Panigrahi, Bijaya Ketan, Series Editor, Chakraborty, Samarjit, Series Editor, Chen, Jiming, Series Editor, Chen, Shanben, Series Editor, Chen, Tan Kay, Series Editor, Dillmann, Rüdiger, Series Editor, Duan, Haibin, Series Editor, Ferrari, Gianluigi, Series Editor, Ferre, Manuel, Series Editor, Hirche, Sandra, Series Editor, Jabbari, Faryar, Series Editor, Jia, Limin, Series Editor, Kacprzyk, Janusz, Series Editor, Khamis, Alaa, Series Editor, Kroeger, Torsten, Series Editor, Liang, Qilian, Series Editor, Martin, Ferran, Series Editor, Ming, Tan Cher, Series Editor, Minker, Wolfgang, Series Editor, Misra, Pradeep, Series Editor, Möller, Sebastian, Series Editor, Mukhopadhyay, Subhas, Series Editor, Ning, Cun-Zheng, Series Editor, Nishida, Toyoaki, Series Editor, Pascucci, Federica, Series Editor, Qin, Yong, Series Editor, Seng, Gan Woon, Series Editor, Speidel, Joachim, Series Editor, Veiga, Germano, Series Editor, Wu, Haitao, Series Editor, Zhang, Junjie James, Series Editor, and Németh, Bálint, editor

Published
2020
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7. Introducing an Inductive Loop Sensor as an Alternative to Record the Phenomena of a Dense Plasma Focus of 400 J

Author

Orellana, Luis, Ardila, Jorge, Avaria, Gonzalo, Cevallos, Benjamín, Pavez, Cristian, Schurch, Roger, Soto, Leopoldo, Angrisani, Leopoldo, Series Editor, Arteaga, Marco, Series Editor, Panigrahi, Bijaya Ketan, Series Editor, Chakraborty, Samarjit, Series Editor, Chen, Jiming, Series Editor, Chen, Shanben, Series Editor, Chen, Tan Kay, Series Editor, Dillmann, Rüdiger, Series Editor, Duan, Haibin, Series Editor, Ferrari, Gianluigi, Series Editor, Ferre, Manuel, Series Editor, Hirche, Sandra, Series Editor, Jabbari, Faryar, Series Editor, Jia, Limin, Series Editor, Kacprzyk, Janusz, Series Editor, Khamis, Alaa, Series Editor, Kroeger, Torsten, Series Editor, Liang, Qilian, Series Editor, Martin, Ferran, Series Editor, Ming, Tan Cher, Series Editor, Minker, Wolfgang, Series Editor, Misra, Pradeep, Series Editor, Möller, Sebastian, Series Editor, Mukhopadhyay, Subhas, Series Editor, Ning, Cun-Zheng, Series Editor, Nishida, Toyoaki, Series Editor, Pascucci, Federica, Series Editor, Qin, Yong, Series Editor, Seng, Gan Woon, Series Editor, Speidel, Joachim, Series Editor, Veiga, Germano, Series Editor, Wu, Haitao, Series Editor, Zhang, Junjie James, Series Editor, and Németh, Bálint, editor

Published
2020
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9. Use of a plasma focus device to study pulsed x-ray effects on peripheral blood lymphocytes: Analysis of chromosome aberrations.

Author

Verdejo, Valentina, Radl, Analía, Barquinero, Joan-Francesc, Jain, Jalaj, Davis, Sergio, Pavez, Cristian, Soto, Leopoldo, and Moreno, José

Subjects
CHROMOSOME abnormalities, CHROMOSOME analysis, PLASMA focus, BLOOD testing, PLASMA devices
Abstract

X-ray pulses (full width at half maximum ∼ 90 ns, dose rate ∼ 107 Gy s−1) were used to irradiate the monolayer of peripheral blood mononucleated cells using the PF-2kJ kilojoule plasma focus device. Four different exposure conditions were evaluated using 5, 10, 20, and 40 pulses, with the mean dose measured by TLD-100 being 0.12 ± 0.02 mGy, 0.14 ± 0.03 mGy, 0.22 ± 0.06 mGy, and 0.47 ± 0.09 mGy, respectively. Cytogenetic analysis showed an increase in all types of chromosomal aberrations following exposure to x-ray pulses. The distribution of dicentrics and centric rings was overdispersed after 5, 10, 20, and 40 pulses. Additionally, after 20 and 40 pulses, the presence of tricentric chromosomes is detected. Chromosome aberration frequencies found in this study were always higher than the estimated frequencies of chromosome aberrations using published dose–effect curves for conventional radiation sources. The overdispersion observed, the elevated maximum relative biological effectiveness (RBEM) and the presence of tricentric chromosomes at the relatively low doses of exposure (<0.5 Gy) seem to indicate that low doses of pulsed x-rays of low energy show similar biological effects as those observed for high-LET radiation. X-ray pulses emitted by PF-2kJ were found to be more efficient in inducing chromosome aberrations, even more than α particles. [ABSTRACT FROM AUTHOR]

Published
2023
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11. Methodology for the use of proportional counters in pulsed fast neutron yield measurements

Author

Tarifeño-Saldivia, Ariel, Mayer, Roberto E., Pavez, Cristian, and Soto, Leopoldo

Subjects
Physics - Instrumentation and Detectors, Physics - Data Analysis, Statistics and Probability, Physics - Plasma Physics
Abstract

This paper introduces in full detail a methodology for the measurement of neutron yield and the necessary efficiency calibration, to be applied to the intensity measurement of neutron bursts where individual neutrons are not resolved in time, for any given moderated neutron proportional counter array. The method allows efficiency calibration employing the detection neutrons arising from an isotopic neutron source. Full statistical study of the procedure is descripted, taking into account contributions arising from counting statistics, piling-up statistics of real detector pulse-height spectra and background fluctuations. The useful information is extracted from the net waveform area of the signal arising from the electric charge accumulated inside the detector tube. Improvement of detection limit is gained, therefore this detection system can be used in detection of low emission neutron pulsed sources with pulses of duration from nanoseconds to up. The application of the methodology to detection systems to be applied for D-D fusion neutrons from plasma focus devices is described. The present work is also of interest to the nuclear community working on fusion by magnetic confinement and lasers, and working on neutron production by accelerators or similar devices., Comment: Submitted to Rev. Sci. Instruments

Published
2011

15. Research on pinches driven by SPPED 2 generator : hard X-ray and neutron emission in plasma focus configuration

Author

Soto, Leopoldo, Moreno, Jose, Silva, Patricio, Sylvester, Gustavo, Zambra, Marcelo, Pavez, Cristian, Raspa, Veronica, Castillo, Fermin, and Kies, Walter

Subjects
Physics - Plasma Physics
Abstract

SPEED2 is a generator based on Marx technology and was designed in the University of Dusseldorf. SPEED2 consists on 40 +/- Marx modules connected in parallel (4.1 mF equivalent Marx generator capacity, 300 kV, 4 MA in short circuit, 187 kJ, 400 ns rise time, dI/dt~1013 A/s). Currently the SPEED2 is operating at the Comision Chilena de Energia Nuclear, CCHEN, Chile, being the most powerful and energetic device for dense transient plasma in the Southern Hemisphere. Most of the previous works developed in SPEED2 at Dusseldorf were done in a plasma focus configuration for soft X-ray emission and the neutron emission from SPEED2 was not completely studied. The research program at CCHEN considers experiments in different pinch configurations (plasma focus, gas puffed plasma focus, gas embedded Z-pinch, wire arrays) at current of hundred of kiloamperes to mega-amperes, using the SPEED2 generator. The Chilean operation has begun implementing and developing diagnostics in a conventional plasma focus configuration operating in deuterium in order to characterize the neutron emission and the hard X-ray production. Silver activation counters, plastics CR39 and scintillator-photomultiplier detectors are used to characterize the neutron emission. Images of metallic plates with different thickness are obtained on commercial radiographic film, Agfa Curix ST-G2, in order to characterize an effective energy of the hard X-ray outside of the discharge ., Comment: 12th International Congress on Plasma Physics, 25-29 October 2004, Nice (France)

Published
2004

17. Hyper-radiosensitivity in tumor cells following exposure to low dose pulsed x-rays emitted from a kilojoule plasma focus device.

Author

Jain, Jalaj, Araya, Hector, Moreno, Jose, Davis, Sergio, Andaur, Rodrigo, Bora, Biswajit, Pavez, Cristian, Marcelain, Katherine, and Soto, Leopoldo

Subjects
PLASMA focus, EXPOSURE dose, PLASMA devices, CELL death, X-rays, CELL lines
Abstract

In the present work, a kilojoule plasma focus device, PF-2 kJ, is adopted as a pulsed x-ray source to study the effects of pulsed radiation in cancer cells. Low dose hyper-radiosensitivity (LDHRS) effects have been explored in various cancer cell lines using conventional x-ray irradiation. To the best of our knowledge, the LDHRS effects have not yet been explored using pulsed x-rays. Cell death was evaluated in human colorectal (DLD-1 and HCT-116) and breast (MCF-7) cancer cell lines (monolayer cell cultures) irradiated with 10 (∼0.24 Gy), 20 (0.61 Gy), and 40 (∼1.1 Gy) pulses (FWHM ∼ 90 ns, dose rate ∼107 Gy/min with a dose of 0.025 Gy per pulse). The LDHRS cell death effect in the DLD-1 cell line irradiated with pulsed x-ray is three times higher than the reported for a conventional continuous x-ray source at two times higher doses. LDHRS was also observed in HCT-116 and MCF-7 cells exposed to 10 and 20 x-ray pulses, respectively, which are reported not to exhibit LDHRS when conventional continuous x-ray sources are used. Besides, a normal colorectal cell line, CCD-841-CoN, does not show a significant cell death at 10 pulses. These preliminary results suggest a selective effect of low-dose pulsed x-rays on cancer cells. The present work demonstrates the applicability of plasma focus devices for cancer research. Further possibilities in the exploration of pulsed x ray of high-dose rate and low total dose in radiotherapy research are opened. [ABSTRACT FROM AUTHOR]

Published
2021
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20. Update on the Scientific Status of the Plasma Focus

Author

Auluck, Sunil, primary, Kubes, Pavel, additional, Paduch, Marian, additional, Sadowski, Marek J., additional, Krauz, Vyacheslav I., additional, Lee, Sing, additional, Soto, Leopoldo, additional, Scholz, Marek, additional, Miklaszewski, Ryszard, additional, Schmidt, Hellmut, additional, Blagoev, Alexander, additional, Samuelli, Maurizio, additional, Seng, Yeow Sing, additional, Springham, Stuart Victor, additional, Talebitaher, Alireza, additional, Pavez, Cristian, additional, Akel, Mohammad, additional, Yap, Seong Ling, additional, Verma, Rishi, additional, Kolacek, Karel, additional, Keat, Paul Lee Choon, additional, Rawat, Rajdeep S., additional, Abdou, Ali, additional, Zhang, Guixin, additional, and Laas, Tõnu, additional

Published
2021
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30. Analysis of Deterioration in a Plasma Focus Device

Author

Zanelli, Daniel, primary, López, Enrique, additional, Pavez, Cristian, additional, Pedreros, José, additional, Jain, Jalaj, additional, Avaria, Gonzalo, additional, Moreno, José, additional, Bora, Biswajit, additional, Davis, Sergio, additional, and Soto, Leopoldo, additional

Published
2018
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34. Methodology for the use of proportional counters in pulsed fast neutron yield measurements

Author

Tarife��o-Saldivia, Ariel, Mayer, Roberto E., Pavez, Cristian, and Soto, Leopoldo

Subjects
Plasma Physics (physics.plasm-ph), Physics - Instrumentation and Detectors, Astrophysics::High Energy Astrophysical Phenomena, Physics - Data Analysis, Statistics and Probability, FOS: Physical sciences, Instrumentation and Detectors (physics.ins-det), Nuclear Experiment, Data Analysis, Statistics and Probability (physics.data-an), Physics - Plasma Physics
Abstract

This paper introduces in full detail a methodology for the measurement of neutron yield and the necessary efficiency calibration, to be applied to the intensity measurement of neutron bursts where individual neutrons are not resolved in time, for any given moderated neutron proportional counter array. The method allows efficiency calibration employing the detection neutrons arising from an isotopic neutron source. Full statistical study of the procedure is descripted, taking into account contributions arising from counting statistics, piling-up statistics of real detector pulse-height spectra and background fluctuations. The useful information is extracted from the net waveform area of the signal arising from the electric charge accumulated inside the detector tube. Improvement of detection limit is gained, therefore this detection system can be used in detection of low emission neutron pulsed sources with pulses of duration from nanoseconds to up. The application of the methodology to detection systems to be applied for D-D fusion neutrons from plasma focus devices is described. The present work is also of interest to the nuclear community working on fusion by magnetic confinement and lasers, and working on neutron production by accelerators or similar devices., Submitted to Rev. Sci. Instruments

Published
2011

39. Characterization of the axial plasma shock in a table top plasma focus after the pinch and its possible application to testing materials for fusion reactors

Author

Soto, Leopoldo, primary, Pavez, Cristian, additional, Moreno, José, additional, Inestrosa-Izurieta, María José, additional, Veloso, Felipe, additional, Gutiérrez, Gonzalo, additional, Vergara, Julio, additional, Clausse, Alejandro, additional, Bruzzone, Horacio, additional, Castillo, Fermín, additional, and Delgado-Aparicio, Luis F., additional

Published
2014
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40. An ultra miniature pinch-focus discharge

Author

Soto, Leopoldo, Pavez, Cristian, Barbaglia, Mario, Clausse, Alejandro, Moreno, José G., Soto, Leopoldo, Plasma Physics and Plasma Technology Laboratory, Chilean Nuclear Energy Commission, Facultad de Física, Universidad de Concepción [Chile], Laboratorio de Plasmas Densos Magnetizados (PLADEMA), and Consejo Nacional de Investigaciones Científicas y Técnicas [Buenos Aires] (CONICET)-Comisión Nacional de Energía Atómica [ARGENTINA] (CNEA)-Universidad Nacional del Centro de la Provincia de Buenos Aires [Buenos Aires] (UNICEN)

Subjects
[PHYS.PHYS.PHYS-PLASM-PH]Physics [physics]/Physics [physics]/Plasma Physics [physics.plasm-ph], [PHYS.PHYS.PHYS-PLASM-PH] Physics [physics]/Physics [physics]/Plasma Physics [physics.plasm-ph]
Abstract

12th International Congress on Plasma Physics, 25-29 October 2004, Nice (France); As a way to investigate the minimum energy to produce a pinch plasma focus discharge, an ultra miniature device has been designed and constructed (nanofocus NF: 5nF, 5-10kV, 5-10kA, 60-250 mJ, 16 ns ns time to peak current). Sub-millimetric anode radius covered by a coaxial insulator were used for experiments in hydrogen. Evidence of pinch was observed in electrical signals in discharges operating at 60 mJ. A single-frame image converter camera (4ns exposure) was used to obtain plasma images in the visible range. The dynamics observed from the photographs is consistent with: a) formation of a plasma sheath close to the insulator surface, b) fast axial motion of the plasma sheath, c) radial compression over the anode, and d) finally the plasma is detached from the anode in the axial direction. The total time since stage a) to d) was observed in ~30 ns. X ray and neutron emission is being studied. Neutron yield of the order of 103 neutron per shot is expected for discharges operating in deuterium at 10kA.

Published
2004

46. Análisis de la valuación patrimonial de una empresa de acuerdo a los principios contables generalmente aceptados

Author

León, Alvaro, Morales, Cecilia, Neira, Carlos, Pavez, Cristian, Echaiz Fernández, Iván, Facultad de Ciencias Economicas y Administrativas, and Escuela de Contadores Auditores

Subjects
Valoración, Chile, Empresas
Abstract

Tesis (Contador Auditor) El presente estudio centra su atención, en forma inmediata cuestionando la base teórica que sustenta el proceso de valuación contable teniendo como base el principio de costo histórico, al cual se somete la información contable, y que incide en la calidad de la misma, perdiendo con esto objetividad para la toma de decisiones. Por otra parte, se proponen alternativas al actual sistema de valuación contable, de manera que contribuya, en forma teórica, a lograr que se solucione esta debilidad de la contabilidad en el mediano plazo, en lo relacionado a los distintos procesos de decisiones, a través, de la generación de información relevante para los diversos usuarios de la misma.

Published
1998

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