40 results on '"E. Faleiro"'
Search Results
2. A fast method to compute the grounding resistance of a coated electrode using the coated electrode equivalent radius
- Author
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E. Faleiro, G. Asensio, G. Denche, and J. Moreno
- Subjects
Energy Engineering and Power Technology ,Electrical and Electronic Engineering - Published
- 2022
3. Discriminant analysis based on spectral statistics applied to TeV cosmic γ/proton separation
- Author
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L. Muñoz, J. Retamosa, E. Faleiro, and Armando Relaño
- Subjects
Physics ,COSMIC cancer database ,Proton ,Astrophysics::High Energy Astrophysical Phenomena ,Separation (statistics) ,Astronomy and Astrophysics ,Cosmic ray ,Astrophysics ,Type (model theory) ,Linear discriminant analysis ,Random matrix ,Statistic ,Computational physics - Abstract
It has been shown that spectral statistics techniques, based on random matrix theory, can be applied to study correlations at ground level between the secondary particles of simulated extensive air showers. The statistical description of shower fronts provided by appropriate spectral measures makes it possible to separate them into different classes depending on the type of the primary cosmic ray. Using a suitable combination of spectral statistics in the framework of discriminant analysis, we introduce a new statistic which separates shower fronts according to the primary type with improved efficiency.
- Published
- 2012
4. Spectral statistics applied to TeV cosmic gamma/proton discrimination
- Author
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E. Faleiro, L. Muñoz, Armando Relaño, and J. Retamosa
- Subjects
Nuclear physics ,Ground level ,Physics ,Atmosphere of Earth ,COSMIC cancer database ,Quality (physics) ,Proton ,Astrophysics::High Energy Astrophysical Phenomena ,Spectral statistics ,Astronomy and Astrophysics ,Particle density ,Random matrix - Abstract
Spectral statistics techniques based on random matrix theory are applied to study the correlations at ground level among secondary particle density distributions of simulated extensive air showers. High-energy interactions of TeV cosmic γ -rays and protons with Earth atmosphere and the resulting extensive air showers have been simulated by means of the CORSIKA Monte Carlo code. The statistical description of shower fronts provided by this new type of analysis allows to distinguish events generated by primary protons from those initiated by primary γ -rays, and leads to a powerful discrimination method whose efficiency is evaluated using the standard quality factors.
- Published
- 2010
5. Power spectrum of nuclear spectra with missing levels and mixed symmetries
- Author
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E. Faleiro, Armando Relaño, J. Retamosa, Rafael A. Molina, and L. Muñoz
- Subjects
[PACS] Chaos in nuclear systems ,Physics ,Nuclear and High Energy Physics ,Sequence ,[PACS] Quantum chaos ,semiclassical methods ,Termodinámica ,Spectral density ,Quantum number ,Spectral line ,Quantum chaos ,Shell model ,Statistical spectroscopy ,Theoretical physics ,Position (vector) ,Homogeneous space ,Fraction (mathematics) - Abstract
8 pages, 2 tables, 7 figures.--PACS nrs.: 21.60.-k; 05.45.Mt; 24.60.Lz.--Available on line on Nov 13, 2006., Sequences of energy levels in nuclei are often plagued with missing levels whose number and position are unknown. It is also quite usual that all the quantum numbers of certain levels cannot be experimentally determined, and thus levels of different symmetries are mixed in the same sequence. The analysis of these imperfect spectra (from the point of view of spectral statistics) is unavoidable if one wants to extract some statistical information. The power spectrum of the δq statistic has emerged in recent years as an important tool for the study of quantum chaos and spectral statistics. We derive analytical expressions for the observed power spectrum in terms of the fraction of observed levels and the number of mixed sequences. These expressions are tested with large shell model spectra simulating realistic experimental situations. A good estimation of the number of mixed symmetries and the fraction of missing levels is obtained by means of a least-squares fit in a wide set of different situations., This work is supported in part by Spanish Government grants BFM2003-04147-C02 and FTN2003-08337-C04-04.
- Published
- 2007
6. Shell-Model studies of chaos and statistical properties in nuclei
- Author
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José María Gómez, E. Faleiro, R. Molina, L. Muñoz, and Armando Relaño
- Subjects
Physics ,History ,SHELL model ,Nuclear Theory ,Information theory ,Computer Science Applications ,Education ,CHAOS (operating system) ,Classical mechanics ,Física nuclear ,Statistical physics ,Time series ,Wave function ,Random matrix ,Excitation ,Energy (signal processing) - Abstract
6 pags., 4 figs. -- 11th International Spring Seminar on Nuclear Physics: Shell Model and Nuclear Structure – achievements of the past two decades 12–16 May 2014, Ischia, Italy, Shell-model calculations with realistic empirical interactions constitute an excellent tool to study statistical properties of nuclei. Using large-scale shell-model calculations in pf- shell nuclei, we study how the onset of chaos depends on different properties of the nuclear interaction and on excitation energy. We make use of classical random matrix theory and other theoretical developments based on information theory and time series analysis. We show that besides energy-level statistics, other statistical properties like the complexity of wave functions are fundamental for a proper determination of the dynamical regime of nuclei. Important deviations from GOE are observed in level fluctuations and in the complexity of wave functions.
- Published
- 2015
7. Power spectrum analysis of experimental Sinai quantum billiards
- Author
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Ulrich Kuhl, L. Muñoz, E. Faleiro, Rafael A. Molina, Armando Relaño, and J. Retamosa
- Subjects
Nonlinear Sciences::Chaotic Dynamics ,Physics ,Chaotic systems ,Quantum mechanics ,General Physics and Astronomy ,Semiclassical physics ,Spectral density ,Periodic orbits ,Time series ,Quantum ,Energy (signal processing) ,Quantum chaos - Abstract
We perform a power spectrum analysis of energy level fluctuations in experimental quantum Sinai billiards. In spite of experimental limitations we find the 1/f behavior expected for quantum chaotic systems. Moreover, the deviations observed at low frequencies are easily explained within the semiclassical periodic orbit theory. In conclusion, it is shown that the power spectrum analysis of energy level fluctuations is a robust signature of quantum chaos.
- Published
- 2006
8. Principal components analysis of Cerenkov photon distributions from extensive air showers applied to GeV gamma–proton discrimination
- Author
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Rafael A. Molina, José María Gómez, L. Muñoz, J. Retamosa, Armando Relaño, Jose Luis Contreras, and E. Faleiro
- Subjects
Nuclear physics ,Physics ,Photon ,COSMIC cancer database ,Proton ,Covariance matrix ,Astrophysics::High Energy Astrophysical Phenomena ,Principal component analysis ,Astrophysics::Instrumentation and Methods for Astrophysics ,Gamma ray ,Astronomy and Astrophysics ,Cosmic ray ,Statistical fluctuations - Abstract
High-energy interactions of cosmic rays with Earth atmosphere and the resulting extensive air showers have been simulated by means of the CORSIKA Monte Carlo code. Statistical fluctuations of the two-dimensional secondary Cerenkov photon density distributions at ground level produced by GeV cosmic γ rays and protons are studied by means of principal components analysis (PCA). This provides a decreasing sequence of covariance matrix eigenvalues that may be fitted to an analytical expression allowing to distinguish among different primary cosmic rays. A very efficient discrimination method of gamma ray induced showers from proton simulated extensive air showers is proposed as a result of this analysis. A cutting parameter is calculated, and the efficiency of the cutting procedure for γ–proton separation is evaluated under experimental conditions.
- Published
- 2006
9. Application of bidimensional power spectrum properties of extensive air shower particle distributions to γ–proton discrimination
- Author
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Armando Relaño, J. Retamosa, José María Gómez, and E. Faleiro
- Subjects
Nuclear physics ,Physics ,Air shower ,Proton ,Astrophysics::High Energy Astrophysical Phenomena ,Frequency domain ,Spectral density ,Particle ,Astronomy and Astrophysics ,Cosmic ray ,Particle density ,Noise (radio) - Abstract
High-energy interactions of cosmic γ rays and protons with the earth atmosphere have been simulated by means of the CORSIKA Monte Carlo code, and the secondary particle density distributions at ground level in the resulting extensive air showers have been studied. It is shown that the power spectrum of the bidimensional particle density fluctuations have features typical of a 1/ f noise in the bidimensional frequency domain, and is found to have different features for different primary cosmic rays. This property is applied to the separation of electromagnetic from proton simulated extensive air showers and it is proposed as a new discrimination method that can be used experimentally for real-time γ–proton separation. A cutting parameter related to the bidimensional power spectrum is calculated and the efficiency of the cutting procedure for γ–proton separation is evaluated.
- Published
- 2004
10. Gamma-hadron discrimination by the multifractal spectrum of 1/f density fluctuations in extensive air showers
- Author
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José María Gómez, E. Faleiro, and Armando Relaño
- Subjects
Physics ,COSMIC cancer database ,Astrophysics::High Energy Astrophysical Phenomena ,Hadron ,chemistry.chemical_element ,Astronomy and Astrophysics ,Cosmic ray ,Multifractal system ,Nuclear physics ,Atmosphere of Earth ,chemistry ,Particle density ,Helium ,Noise (radio) - Abstract
High-energy interactions of cosmic γ rays and protons and also helium, oxygen and iron nuclei with the Earth atmosphere have been simulated by means of the CORSIKA Monte Carlo code, and the secondary-particle density distributions at ground level in the resulting extensive air showers (EAS) have been studied. It is shown that the fluctuations of the particle density distributions have features typical of a 1/f noise. The multifractal spectrum of the samples is obtained and is found to have different features for different primary cosmic rays. This property is applied to the separation of electromagnetic from hadronic simulated EAS and it is proposed as a discrimination method when real data are available. A cutting parameter related to the multifractal spectrum is calculated and the efficiency of the cutting procedure for γ-hadron separation is evaluated.
- Published
- 2003
11. Multifractal characterisation of fluctuations in simulated Extensive Air Showers
- Author
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E. Faleiro and J. M. G. Gozmez
- Subjects
Physics ,Nuclear physics ,Atmosphere of Earth ,Astrophysics::High Energy Astrophysical Phenomena ,Gamma ray ,General Physics and Astronomy ,Cosmic ray ,Multifractal system ,Function (mathematics) ,Polar coordinate system ,Noise (electronics) ,Scaling ,Computational physics - Abstract
High-energy interactions of gamma rays and protons with the Earth atmosphere have been simulated by means of the CORSIKA Monte Carlo code, and the secondary-particle density distributions in the resulting extensive air showers, at ground level, have been studied. It is shown that the fluctuations of the density distributions as a function of the polar angle have features typical of a 1/f noise. The sample is then analysed in order to study its scaling behaviour and we find that it can be parametrized by means of a universal multifractal approach.
- Published
- 1999
12. A study of fluctuations in extensive air showers simulated by Monte Carlo methods
- Author
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E. Faleiro and Jose Luis Contreras
- Subjects
Physics ,Nuclear and High Energy Physics ,SIMPLE (dark matter experiment) ,business.industry ,Hadron ,Monte Carlo method ,Computational physics ,Atmosphere ,Ground level ,Optics ,Flicker noise ,Deconvolution ,business ,Noise (radio) - Abstract
We have simulated the interactions of high energy rays and protons with the terrestrial atmosphere, and studied the ground level behaviour of the distributions of secondary . The fluctuation seen in these distributions show the typical aspect of a flicker noise. We show how deconvolution of this noise leads to an improved /hadron discrimination in a simple separation scheme.
- Published
- 1998
13. Methods to determine the angular resolution of the HEGRA extended air shower scintillator array
- Author
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W. Stamm, V. Fonseca, M. Rozanska, José Fernández, K. H. Becker, E. Lorenz, A. Karle, E. Faleiro, V. Haustein, M. Merck, M. Probst, K. Sauerland, C. Seseña, F. Just, J. Prahl, F. Krennrich, R. Eckmann, F. Arqueros, M. Kühn, N. Müller, M. Samorski, S. Martinez, R. Plaga, H. Meyer, G. Heinzelmann, P. Fernandez, I. Holl, H. Sander, and M. Bott-Bodenhausen
- Subjects
Physics ,Nuclear physics ,Air shower ,Proton ,Resolution (electron density) ,HEGRA ,Astronomy and Astrophysics ,Angular resolution ,Scintillator - Abstract
A precise knowledge of the angular resolution of scintillator arrays used to observe extended air showers (EAS) is of key importance in the search for VHE/UHE γ point sources. Four independent methods have been used to determine the mean resolution for which a value of 〈ΔΘ63〉 of 0.8°(1.0°) at a proton threshold of 50 (40) TeV has been found for the HEGRA EAS-array.
- Published
- 1996
14. A search for gamma radiation above 24 TeV energy from cosmic point sources
- Author
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Dieter Renker, E. Faleiro, W. Stamm, R. Plaga, J. Prahl, R. N. Sooth, H. Krawwcczynski, José Fernández, F. Arqueros, F. Just, K. Sauerland, S. Martinez, V. Fonseca, D. Schmele, M. Merck, V. Matheis, P. Fernandez, N. Müller, M. Kühn, E. Lorenz, A. Karle, M. Samorski, F. Krennrich, H. Meyer, B. Wiebel, V. Haustein, I. Holl, H. Sander, V. Henke, K. H. Becker, G. Heinzelmann, A. Lindner, R. Mirzoyan, and M. Rozanska
- Subjects
Physics ,COSMIC cancer database ,Photon ,Infrared ,Astrophysics::High Energy Astrophysical Phenomena ,HEGRA ,Astronomy ,Astronomy and Astrophysics ,Cosmic ray ,Astrophysics::Cosmology and Extragalactic Astrophysics ,Astrophysics ,Radiation ,Crab Nebula ,Angular resolution - Abstract
The HEGRA collaboration has searched for γ-ray emission from 36 potential cosmic point sources with the wide angle air Cerenkov detector AIROBICC which is part of the HEGRA cosmic ray detector complex on La Palma. AIROBICC has a γ-ray energy threshold of around 24 TeV and a mean angular resolution of 0.29 °. None of the sources could be found. Upper limits to their fluxes are given. For the VHE γ-ray emitters, the Crab nebula and Mrk 421, these flux limits are below those extrapolated from lower energy observations. Our lower limit for Mrk 421 might be interpreted either as being due to an energy cut-off in the acceleration mechanism or to the onset of γ-interaction with photons of the universal infrared background.
- Published
- 1995
15. Recent results in quantum chaos and its applications to atomic nuclei
- Author
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Rafael Molina, J. Retamosa, L. Muñoz, E. Faleiro, Armando Relaño, and José María Gómez
- Subjects
Physics ,History ,Synchronization of chaos ,Termodinámica ,Chaotic ,Noise (electronics) ,Spectral line ,Quantum chaos ,Computer Science Applications ,Education ,Quantum mechanics ,Atomic nucleus ,Quantum ,Excitation - Abstract
A survey of chaotic dynamics in atomic nuclei is presented, using on the one hand standard statistics of quantum chaos studies, and on the other a new approach based on time series analysis methods. The study of shell-model spectra in the pf shell shows that nuclear chaos is strongly isopin dependent and increases with excitation energy. On the other hand, it is found that chaotic quantum systems exhibit 1/f noise and regular systems exhibit 1/f 2 behaviour. It is shown that the time series approach can be used to calculate quite accurately the fraction of missing levels and the existence of mixed symmetries in experimental level spectra.
- Published
- 2011
16. Perspectives on 1/f noise in quantum chaos
- Author
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L. Muñoz, Rafael Molina, J. Retamosa, E. Faleiro, José María Gómez, Armando Relaño, Ministerio de Ciencia e Innovación (España), and Universidad Complutense de Madrid
- Subjects
History ,Pure mathematics ,Synchronization of chaos ,Chaotic ,Spectral density ,Space (mathematics) ,Noise (electronics) ,Quantum chaos ,Computer Science Applications ,Education ,Phase space ,Homogeneous space ,Statistical physics ,Mathematics - Abstract
6 pags., 2 figs. -- XXXIII Symposium on Nuclear Physics 5–8 January 2010, Hacienda Cocoyoc, Morelos, Mexico, The power spectrum of the 5 statistic of quantum spectra presents 1/f(alpha) noise. For chaotic systems alpha = 1 while for regular systems alpha = 2. Although the transition from regularity to chaos is non universal, for a wide variety of systems with a mixed phase space the value of a is intermediate between 1 and 2 and can be related to the fraction of regular or chaotic orbits in the total phase space. This statistic can be a very useful tool for the analysis of experimental spectra, specially in the case of missing levels or spectral sequences with mixed symmetries., This research has been supported in part by Spanish Government grant No. FIS2009- 07277 and No. FIS2006-12783-C03-02, CSPD-2007-00042-Ingenio2010, and by the Universidad Complutense de Madrid grant UCM-910059. A.R. is supported by the CPAN-Consolider program.
- Published
- 2010
17. RECENT DEVELOPMENTS IN THE SPECTRAL FLUCTUATIONS OF NUCLEI, HADRONS AND OTHER QUANTUM SYSTEMS
- Author
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R. Molina, J. Gómez, E. Faleiro, Armando Relaño, J. Retamosa, and L. Muñoz
- Subjects
Physics ,Quantum dynamics ,Quantum mechanics ,Principal quantum number ,Hadron ,Quantum ,Quantum chaos - Published
- 2008
18. Power spectrum characterization of the continuous gaussian ensemble
- Author
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E. Faleiro, J. Retamosa, Rafael A. Molina, Armando Relaño, and L. Muñoz
- Subjects
[PACS] Quantum chaos ,semiclassical methods ,Level repulsion ,Gaussian ,Gaussian processes ,Matrix algebra ,01 natural sciences ,Power law ,Noise (electronics) ,010305 fluids & plasmas ,[PACS] Statistical theory and fluctuations in nuclei ,symbols.namesake ,Matrix (mathematics) ,Quantum mechanics ,0103 physical sciences ,Fluctuations ,010306 general physics ,Gaussian process ,Physics ,[PACS] Matrix theory ,1/f noise ,Termodinámica ,Random processes ,Spectral density ,Física ,Function (mathematics) ,Minería ,symbols ,Numerical analysis - Abstract
11 pages, 3 figures.-- PACS nrs.: 05.45.Mt; 02.10.Yn; 24.60.-k.-- PMID: 18517325 [PubMed]., The continuous Gaussian ensemble, also known as the v-Gaussian or v-Hermite ensemble, is a natural extension of the classical Gaussian ensembles of real (v=1), complex (v=2), or quaternion (v=4) matrices, where v is allowed to take any positive value. From a physical point of view, this ensemble may be useful to describe transitions between different symmetries or to describe the terrace-width distributions of vicinal surfaces. Moreover, its simple form allows one to speed up and increase the efficiency of numerical simulations dealing with large matrix dimensions. We analyze the long-range spectral correlations of this ensemble by means of the δn statistic. We derive an analytical expression for the average power spectrum of this statistic, [overline Pk[sup δ]], based on approximated forms for the two-point cluster function and the spectral form factor. We find that the power spectrum of δn evolves from [overline Pk[sup δ]] proportional to 1/k at v=1 to [overline Pk[sup δ]] proportional to 1/k^2 at v=0. Relevantly, the transition is not homogeneous with a 1/fα noise at all scales, but heterogeneous with coexisting 1/f and 1/f^2 noises. There exists a critical frequency kc proportional to v that separates both behaviors: below kc, [overline Pk[sup δ]] follows a 1/f power law, while beyond kc, it transits abruptly to a 1/f^2 power law. For v>1 the 1/f noise dominates through the whole frequency range, unveiling that the 1/f correlation structure remains constant as we increase the level repulsion and reduce to zero the amplitude of the spectral fluctuations. All these results are confirmed by stringent numerical calculations involving matrices with dimensions up to 10^5., This work was supported in part by Spanish Government Grants Nos. FIS2006-12783-C03-01 and FIS2006-12783-C03-02 and by Comunidad de Madrid–CSIC Grant No. 200650M012. A.R. was supported by the Spanish program "Juan de la Cierva".
- Published
- 2008
19. 1/f Fluctuations in Cosmic Ray Extensive Air Showers
- Author
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E. Faleiro and J.M.G. Gómez
- Subjects
Physics ,Nuclear physics ,Atmosphere of Earth ,Astrophysics::High Energy Astrophysical Phenomena ,Cosmic ray ,Function (mathematics) ,Multifractal system ,Polar coordinate system ,Particle density ,Noise (electronics) ,Scaling - Abstract
The fluctuations of the particle density distributions in extensive air showers have been studied at ground level. In order to achieve meaningful statistics, the interaction of cosmic rays with the earth atmosphere has been simulated by means of the CORSIKA Monte Carlo code. It is shown that the fluctuations of the particle density distributions as a function of the polar angle have features typical of a 1/f noise. The sample is then analysed in order to study its scaling behaviour and we find that it can be parametrized by means of a universal multifractal approach.
- Published
- 2007
20. Chaotic Behavior of Nuclear Systems
- Author
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R. Molina, Armando Relaño, J. Gómez, J. Retamosa, L. Muñoz, and E. Faleiro
- Subjects
Physics ,Classical mechanics ,Quantum mechanics ,Synchronization of chaos ,Chaotic - Published
- 2007
21. Chaos and 1/f noise in nuclear spectra
- Author
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E. Faleiro, R. Molina, J. Retamosa, Armando Relaño, L. Muñoz, and J. Gómez
- Subjects
Physics ,symbols.namesake ,Fourier transform ,Quantum mechanics ,Quantum noise ,symbols ,Spectral density ,Energy level ,Noise (electronics) ,Random matrix ,Quantum ,Quantum chaos - Abstract
Many complex systems in nature and in human society exhibit time fluctuations characterized by a power spectrum S(f) which is a power function of the frequency f. Examples with this behavior are the Sun spot activity, the human heartbeat, the DNA sequence, or Bach’s First Brandenburg Concert. In this work, we show that the energy spectrum fluctuations of quantum systems can be formally considered as a discrete time series, with energy playing the role of time. Because of this analogy, the fluctuations of quantum energy spectra can be studied using traditional methods of time series, like calculating the Fourier transform and studying the power spectrum. We present the results for paradigmatic quantum chaotic systems like atomic nuclei (by means of large scale shell‐model calculations) and the predictions of random matrix theory. We have found a surprising general property of quantum systems: The energy spectra of chaotic quantum systems are characterized by 1/f noise, while regular quantum systems exhibit...
- Published
- 2006
22. 1/f noise and very high spectral rigidity
- Author
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J. Retamosa, E. Faleiro, Armando Relaño, Rafael A. Molina, A. P. Zuker, Institut de Recherches Subatomiques (IReS), and Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Cancéropôle du Grand Est-Université Louis Pasteur - Strasbourg I-Centre National de la Recherche Scientifique (CNRS)
- Subjects
[PACS] Quantum chaos ,semiclassical methods ,[PHYS.NUCL]Physics [physics]/Nuclear Theory [nucl-th] ,Termodinámica ,Chaotic ,Spectral density ,01 natural sciences ,Power law ,Quantum chaos ,Spectral line ,[PACS] Time series analysis ,010305 fluids & plasmas ,Rigidity (electromagnetism) ,Discrete time and continuous time ,Quantum mechanics ,0103 physical sciences ,05.45.Mt, 05.45.Tp, 05.40.-a ,010306 general physics ,Quantum ,Mathematics ,[PACS] Fluctuation phenomena, random processes, noise, and Brownian motion - Abstract
6 pages, 1 table, 4 figures.--PACS nrs.: 05.45.Mt; 05.45.Tp; 05.40.-a, It was recently pointed out that the spectral fluctuations of quantum systems are formally analogous to discrete time series, and therefore their structure can be characterized by the power spectrum of the signal. Moreover, it is found that the power spectrum of chaotic spectra displays a 1/f behavior, while that of regular systems follows a 1/f2 law. This analogy provides a link between the concepts of spectral rigidity and antipersistence. Trying to get a deeper understanding of this relationship, we have studied the correlation structure of spectra with high spectral rigidity. Using an appropriate family of random Hamiltonians, we increase the spectral rigidity up to hindering completely the spectral fluctuations. Analyzing the long range correlation structure a neat power law 1/f has been found for all the spectra, along the whole process. Therefore, 1/f noise is the characteristic fingerprint of a transition that, preserving the scale-free correlation structure, hinders completely the fluctuations of the spectrum., This work is supported in part by Spanish Government Grants No. BFM2003-04147 and No. FTN2003-08337-C04-04.
- Published
- 2006
23. Spectral statistics in noninteracting many-particle systems
- Author
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Armando Relaño, E. Faleiro, L. Muñoz, Rafael A. Molina, and J. Retamosa
- Subjects
Physics ,Particle system ,[PACS] Quantum chaos ,semiclassical methods ,Termodinámica ,[PACS] Statistical theory and fluctuations ,Statistical fluctuations ,Quantum chaos ,Many-body problem ,Mean field theory ,Quantum mechanics ,[PACS] Numerical simulations of chaotic systems ,Statistical physics ,Heuristic argument ,Quantum ,Identical particles - Abstract
14 pages, 3 tables, 13 figures.--PACS nrs.:05.45.Mt; 05.45.Pq; 24.60.-k, It is widely accepted that the statistical properties of energy level spectra provide an essential characterization of quantum chaos. Indeed, the spectral fluctuations of many different systems like quantum billiards, atoms, or atomic nuclei have been studied. However, noninteracting many-body systems have received little attention, since it is assumed that they must exhibit Poisson-like fluctuations. Apart from a heuristic argument of Bloch, there are neither systematic numerical calculations nor a rigorous derivation of this fact. Here we present a rigorous study of the spectral fluctuations of noninteracting identical particles moving freely in a mean field emphasizing the evolution with the number of particles N as well as with the energy. Our results are conclusive. For N2 the spectra of these systems exhibit Poisson fluctuations provided that we consider sufficiently high excitation energies. Nevertheless, when the mean field is chaotic there exists a critical energy scale Lc; beyond this scale, the fluctuations deviate from the Poisson statistics as a reminiscence of the statistical properties of the mean field., This work is supported in part by Spanish Government Grants No. BFM2003-04147 and No. FTN2003-08337-C04-04.
- Published
- 2006
24. Correlation structure of theδnstatistic for chaotic quantum systems
- Author
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J. Retamosa, Armando Relaño, E. Faleiro, and José María Gómez
- Subjects
Correlation function ,Series (mathematics) ,Discrete time and continuous time ,Termodinámica ,Mathematical analysis ,Chaotic ,Spectral density ,Noise (electronics) ,Random matrix ,Quantum chaos ,Mathematics - Abstract
The existence of a formal analogy between quantum energy spectra and discrete time series has been recently pointed out. When the energy level fluctuations are described by means of the δ_(n) statistic, it is found that chaotic quantum systems are characterized by 1/f noise, while regular systems are characterized by 1/f(2). In order to investigate the correlation structure of the δ_(n) statistic, we study the qth-order height-height correlation function C-q(tau), which measures the momentum of order q, i.e., the average qth power of the signal change after a time delay tau. It is shown that this function has a logarithmic behavior for the spectra of chaotic quantum systems, modeled by means of random matrix theory. On the other hand, since the power spectrum of chaotic energy spectra considered as time series exhibit 1/f noise, we investigate whether the qth-order height-height correlation function of other time series with 1/f noise exhibits the same properties. A time series of this kind can be generated as a linear combination of cosine functions with arbitrary phases. We find that the logarithmic behavior arises with great accuracy for time series generated with random phases.
- Published
- 2005
25. Chaos and 1/f noise in nuclear spectra
- Author
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R. Molina, E. Faleiro, J. M. G. Gómez, Armando Relaño, J. Retamosa, and Covello, Aldo
- Subjects
Physics ,Complex system ,Energy level ,Semiclassical physics ,Spectral density ,Física ,Statistical physics ,Random matrix ,Noise (electronics) ,Quantum ,Quantum chaos - Abstract
Many complex systems in nature and in human society exhibit time fluctuations characterized by a power spectrum S(f) which is a power function of the frequency f . Examples with this behavior are the Sun spot activity, the human heartbeat, the DNA sequence, or Bach’s First Brandenburg Concert. In this work, we show that the energy spectrum fluctuations of quantum systems can be formally considered as a discrete time series, with energy playing the role of time. Because of this analogy, the fluctuations of quantum energy spectra can be studied using traditional methods of time series, like calculating the Fourier transform and studying the power spectrum. We present the results for paradigmatic quantum chaotic systems like atomic nuclei (by means of large scale shell-model calculations) and the predictions of random matrix theory. We have found a surprising general property of quantum systems: The energy spectra of chaotic quantum systems are characterized by 1= f noise, while regular quantum systems exhibit 1= f^2 noise. Some other interesting applications of this time series analogy are a test of the existence of quantum chaos remnants in the nuclear masses, and the study of the order to chaos transition in semiclassical systems. In this case, it is found that the energy level spectrum exhibits 1= f^α noise with the exponent changing smoothly from α = 2 in regular systems to α= 1 in chaotic systems.
- Published
- 2005
26. 1/ƒ^(α) noise in spectral fluctuations of quantum systems
- Author
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J. Retamosa, José María Gómez, Armando Relaño, Luca Salasnich, E. Faleiro, Marko Vranicar, and Marko Robnik
- Subjects
Quantum phase transition ,Physics ,Termodinámica ,General Physics and Astronomy ,Spectral density ,Observable ,Quantum phases ,01 natural sciences ,Power law ,Quantum chaos ,010305 fluids & plasmas ,Theoretical physics ,Quantum mechanics ,0103 physical sciences ,Quantum system ,010306 general physics ,Energy (signal processing) - Abstract
The power law $1/{f}^{\ensuremath{\alpha}}$ in the power spectrum characterizes the fluctuating observables of many complex natural systems. Considering the energy levels of a quantum system as a discrete time series where the energy plays the role of time, the level fluctuations can be characterized by the power spectrum. Using a family of quantum billiards, we analyze the order-to-chaos transition in terms of this power spectrum. A power law $1/{f}^{\ensuremath{\alpha}}$ is found at all the transition stages, and it is shown that the exponent $\ensuremath{\alpha}$ is related to the chaotic component of the classical phase space of the quantum system.
- Published
- 2005
27. Principal components analysis of extensive air showers applied to the identification of cosmic TeV gamma-rays
- Author
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J. Retamosa, Armando Relaño, E. Faleiro, L. Muñoz, and José María Gómez
- Subjects
Physics ,Polynomial ,COSMIC cancer database ,Proton ,Covariance matrix ,Astrophysics::High Energy Astrophysical Phenomena ,Termodinámica ,Gamma ray ,Astronomy and Astrophysics ,Cosmic ray ,Nuclear physics ,Space and Planetary Science ,Principal component analysis ,Eigenvalues and eigenvectors - Abstract
We apply a principal components analysis (PCA) to the secondary particle density distributions at ground level produced by cosmic gamma-rays and protons. For this purpose, high-energy interactions of cosmic rays with Earth's atmosphere and the resulting extensive air showers have been simulated by means of the CORSIKA Monte Carlo code. We show that a PCA of the two-dimensional particle density fluctuations provides a decreasing sequence of covariance matrix eigenvalues that have typical features of a polynomial law, which are different for different primary cosmic rays. This property is applied to the separation of electromagnetic showers from proton simulated extensive air showers, and it is proposed as a new discrimination method that can be used experimentally for gamma-proton separation. A cutting parameter related to the polynomial behavior of the decreasing sequence of covariance matrix eigenvalues is calculated, and the efficiency of the cutting procedure for gamma-proton separation is evaluated.
- Published
- 2004
28. 1/f alpha noise in spectral fluctuations of quantum systems
- Author
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J M G, Gómez, A, Relaño, J, Retamosa, E, Faleiro, L, Salasnich, M, Vranicar, and M, Robnik
- Subjects
Nonlinear Dynamics ,Quantum Theory ,Models, Theoretical ,Models, Biological - Abstract
The power law 1/f(alpha) in the power spectrum characterizes the fluctuating observables of many complex natural systems. Considering the energy levels of a quantum system as a discrete time series where the energy plays the role of time, the level fluctuations can be characterized by the power spectrum. Using a family of quantum billiards, we analyze the order-to-chaos transition in terms of this power spectrum. A power law 1/f(alpha) is found at all the transition stages, and it is shown that the exponent alpha is related to the chaotic component of the classical phase space of the quantum system.
- Published
- 2004
29. Theoretical derivation of 1/f noise in quantum chaos
- Author
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Rafael A. Molina, José María Gómez, Armando Relaño, L. Muñoz, J. Retamosa, and E. Faleiro
- Subjects
Physics ,Integrable system ,Termodinámica ,Chaotic ,General Physics and Astronomy ,Spectral density ,Semiclassical physics ,FOS: Physical sciences ,Nonlinear Sciences - Chaotic Dynamics ,01 natural sciences ,Noise (electronics) ,Quantum chaos ,010305 fluids & plasmas ,Quantum mechanics ,0103 physical sciences ,Chaotic Dynamics (nlin.CD) ,010306 general physics ,Random matrix ,Quantum - Abstract
It was recently conjectured that 1/f noise is a fundamental characteristic of spectral fluctuations in chaotic quantum systems. This conjecture is based on the behavior of the power spectrum of the excitation energy fluctuations, which is different for chaotic and integrable systems. Using random matrix theory we derive theoretical expressions that explain the power spectrum behavior at all frequencies. These expressions reproduce to a good approximation the power laws of type 1/f (1/f^2) characteristics of chaotic (integrable) systems, observed in almost the whole frequency domain. Although we use random matrix theory to derive these results, they are also valid for semiclassical systems., Comment: 5 pages (Latex), 3 figures
- Published
- 2004
- Full Text
- View/download PDF
30. Quantum chaos and 1/f noise
- Author
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J. Retamosa, E. Faleiro, Armando Relaño, Rafael A. Molina, and J. M. G. Gómez
- Subjects
Physics ,Discrete time and continuous time ,Quantum mechanics ,Termodinámica ,Chaotic ,General Physics and Astronomy ,Spectral density ,Quantum ,Noise (electronics) ,Energy (signal processing) ,Quantum chaos ,Spectral line - Abstract
The main signature of chaos in a quantum system is provided by spectral statistical analysis of the nearest-neighbor spacing distribution P(s) and the spectral rigidity given by the Delta(3)(L) statistic. It is shown that some standard unfolding procedures, such as local unfolding and Gaussian broadening, lead to a spurious saturation of Delta(3)(L) that spoils the relationship of this statistic with the regular or chaotic motion of the system. This effect can also be misinterpreted as Berry's saturation.
- Published
- 2002
31. GAMMA/HADRON SEPARATION USING THE MULTIFRACTAL SPECTRUM FROM 1/<font>F</font> FLUCTUATIONS IN SIMULATED EXTENSIVE AIR SHOWERS
- Author
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J. M. G. Gómez, Armando Relaño, and E. Faleiro
- Subjects
Nuclear physics ,Physics ,Quantum electrodynamics ,Hadron ,Separation (aeronautics) ,Spectrum (functional analysis) ,Multifractal system - Published
- 2002
32. Search for UHE γ sources with the HEGRA detector
- Author
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M. Rozanska, K. Sauerland, M. Merck, M. Probst, M. Kühn, W. Stamm, I. Holl, P. Fernandez, E. Faleiro, C. Seseña, J. Prahl, José Fernández, V. Fonseca, S. Martinez, A. Karle, V. Haustein, K. H. Becker, H. Meyer, G. Heinzelmann, F. Just, F. Arqueros, E. Lorenz, K. Daum, M. Samorski, F. Krennrich, N. Müller, R. Plaga, and H. Sander
- Subjects
Physics ,Steady state (electronics) ,Air shower ,Physics::Instrumentation and Detectors ,Astrophysics::High Energy Astrophysical Phenomena ,Detector ,Scintillation counter ,HEGRA ,High Energy Physics::Experiment ,Angular resolution ,Astrophysics ,Scintillator ,Galaxy - Abstract
The HEGRA collaboration has collected 225 million air shower events with a scintillator array distributed over 3.2×104 m2 in the time between 1989 and 1992. We have searched the data for steady state and sporadic emission from point sources. The median energy of γ showers registers by our detector is about 75 TeV and the average angular resolution 0.7°. No significant steady state or sporadic excess has been found. Upper limits are presented.
- Published
- 1992
33. Estimation of an Upper Bound to the Value of the Step Potentials in Two-Layered Soils from Grounding Resistance Measurements.
- Author
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Moreno J, Simon P, Faleiro E, Asensio G, and Fernandez JA
- Abstract
Due to the constant updating of regulatory standards on safety issues in electrical installations, limits are established for the maximum step potential that an installation can hold in a ground fault situation. In this paper, an upper bound to the maximum value of the step potentials arising in the soil surface when a fault takes place in a grounded electrical installation is estimated by means of a simple procedure. The direct measurement of the grounding electrode resistance together with some information about the soil resistivity and the knowledge of characteristic parameters of the electrode are used for the calculation of that upper bound. The procedure is tested at numerical simulation level by using different electrodes in several different scenarios corresponding to two-layered soils with different resistivity ratios. The dependency of the calculated upper bound with the electrode burial depth is also studied. Finally, a real case study is presented, and the results of the field measurements are shown as an example of the validity of the procedure., Competing Interests: The authors declare no conflict of interest
- Published
- 2020
- Full Text
- View/download PDF
34. Power-spectrum characterization of the continuous Gaussian ensemble.
- Author
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Relaño A, Muñoz L, Retamosa J, Faleiro E, and Molina RA
- Abstract
The continuous Gaussian ensemble, also known as the nu -Gaussian or nu -Hermite ensemble, is a natural extension of the classical Gaussian ensembles of real (nu=1) , complex (nu=2) , or quaternion (nu=4) matrices, where nu is allowed to take any positive value. From a physical point of view, this ensemble may be useful to describe transitions between different symmetries or to describe the terrace-width distributions of vicinal surfaces. Moreover, its simple form allows one to speed up and increase the efficiency of numerical simulations dealing with large matrix dimensions. We analyze the long-range spectral correlations of this ensemble by means of the delta(n) statistic. We derive an analytical expression for the average power spectrum of this statistic, P(k)(delta)[over ] , based on approximated forms for the two-point cluster function and the spectral form factor. We find that the power spectrum of delta(n) evolves from P(k)(delta)[over ] proportional, variant1/k at nu=1 to P(k)(delta)[over ] proportional, variant1/k(2) at nu=0 . Relevantly, the transition is not homogeneous with a 1/f(alpha) noise at all scales, but heterogeneous with coexisting 1/f and 1/f(2) noises. There exists a critical frequency k(c) proportional, variant nu that separates both behaviors: below k(c) , P(k)(delta)[over ] follows a 1/f power law, while beyond k(c) , it transits abruptly to a 1/f(2) power law. For nu >1 the 1/f noise dominates through the whole frequency range, unveiling that the 1/f correlation structure remains constant as we increase the level repulsion and reduce to zero the amplitude of the spectral fluctuations. All these results are confirmed by stringent numerical calculations involving matrices with dimensions up to 10(5) .
- Published
- 2008
- Full Text
- View/download PDF
35. Spectral statistics in noninteracting many-particle systems.
- Author
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Muñoz L, Faleiro E, Molina RA, Relaño A, and Retamosa J
- Abstract
It is widely accepted that the statistical properties of energy level spectra provide an essential characterization of quantum chaos. Indeed, the spectral fluctuations of many different systems like quantum billiards, atoms, or atomic nuclei have been studied. However, noninteracting many-body systems have received little attention, since it is assumed that they must exhibit Poisson-like fluctuations. Apart from a heuristic argument of Bloch, there are neither systematic numerical calculations nor a rigorous derivation of this fact. Here we present a rigorous study of the spectral fluctuations of noninteracting identical particles moving freely in a mean field emphasizing the evolution with the number of particles N as well as with the energy. Our results are conclusive. For N > or =2 the spectra of these systems exhibit Poisson fluctuations provided that we consider sufficiently high excitation energies. Nevertheless, when the mean field is chaotic there exists a critical energy scale L(c); beyond this scale, the fluctuations deviate from the Poisson statistics as a reminiscence of the statistical properties of the mean field.
- Published
- 2006
- Full Text
- View/download PDF
36. 1/f noise and very high spectral rigidity.
- Author
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Relaño A, Retamosa J, Faleiro E, Molina RA, and Zuker AP
- Abstract
It was recently pointed out that the spectral fluctuations of quantum systems are formally analogous to discrete time series, and therefore their structure can be characterized by the power spectrum of the signal. Moreover, it is found that the power spectrum of chaotic spectra displays a 1/f behavior, while that of regular systems follows a 1/f2 law. This analogy provides a link between the concepts of spectral rigidity and antipersistence. Trying to get a deeper understanding of this relationship, we have studied the correlation structure of spectra with high spectral rigidity. Using an appropriate family of random Hamiltonians, we increase the spectral rigidity up to hindering completely the spectral fluctuations. Analyzing the long range correlation structure a neat power law 1/f has been found for all the spectra, along the whole process. Therefore, 1/f noise is the characteristic fingerprint of a transition that, preserving the scale-free correlation structure, hinders completely the fluctuations of the spectrum.
- Published
- 2006
- Full Text
- View/download PDF
37. Correlation structure of the deltan statistic for chaotic quantum systems.
- Author
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Relaño A, Retamosa J, Faleiro E, and Gómez JM
- Abstract
The existence of a formal analogy between quantum energy spectra and discrete time series has been recently pointed out. When the energy level fluctuations are described by means of the statistic, it is found that chaotic quantum systems are characterized by noise, while regular systems are characterized by . In order to investigate the correlation structure of the statistic, we study the -order height-height correlation function , which measures the momentum of order , i.e., the average power of the signal change after a time delay . It is shown that this function has a logarithmic behavior for the spectra of chaotic quantum systems, modeled by means of random matrix theory. On the other hand, since the power spectrum of chaotic energy spectra considered as time series exhibit noise, we investigate whether the -order height-height correlation function of other time series with noise exhibits the same properties. A time series of this kind can be generated as a linear combination of cosine functions with arbitrary phases. We find that the logarithmic behavior arises with great accuracy for time series generated with random phases.
- Published
- 2005
- Full Text
- View/download PDF
38. 1/f alpha noise in spectral fluctuations of quantum systems.
- Author
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Gómez JM, Relaño A, Retamosa J, Faleiro E, Salasnich L, Vranicar M, and Robnik M
- Subjects
- Models, Biological, Nonlinear Dynamics, Models, Theoretical, Quantum Theory
- Abstract
The power law 1/f(alpha) in the power spectrum characterizes the fluctuating observables of many complex natural systems. Considering the energy levels of a quantum system as a discrete time series where the energy plays the role of time, the level fluctuations can be characterized by the power spectrum. Using a family of quantum billiards, we analyze the order-to-chaos transition in terms of this power spectrum. A power law 1/f(alpha) is found at all the transition stages, and it is shown that the exponent alpha is related to the chaotic component of the classical phase space of the quantum system.
- Published
- 2005
- Full Text
- View/download PDF
39. Theoretical derivation of 1/f noise in quantum chaos.
- Author
-
Faleiro E, Gómez JM, Molina RA, Muñoz L, Relaño A, and Retamosa J
- Abstract
It was recently conjectured that 1/f noise is a fundamental characteristic of spectral fluctuations in chaotic quantum systems. This conjecture is based on the power spectrum behavior of the excitation energy fluctuations, which is different for chaotic and integrable systems. Using random matrix theory, we derive theoretical expressions that explain without free parameters the universal behavior of the excitation energy fluctuations power spectrum. The theory gives excellent agreement with numerical calculations and reproduces to a good approximation the 1/f (1/f(2)) power law characteristic of chaotic (integrable) systems. Moreover, the theoretical results are valid for semiclassical systems as well.
- Published
- 2004
- Full Text
- View/download PDF
40. Quantum chaos and 1/f noise.
- Author
-
Relaño A, Gómez JM, Molina RA, Retamosa J, and Faleiro E
- Abstract
It is shown that the energy spectrum fluctuations of quantum systems can be formally considered as a discrete time series. The power spectrum behavior of such a signal for different systems suggests the following conjecture: The energy spectra of chaotic quantum systems are characterized by 1/f noise.
- Published
- 2002
- Full Text
- View/download PDF
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