arXiv subjects

R. Perez

Publications and source records attributed to R. Perez.

10 recordsLinked to original sources

arXiv2021

Study of neutrino-nucleus reactions with CRISP Program (0 < $E_ν$ < 3 GeV)

The neutrino-nucleus reactions are studied at energies from 0 to 3 GeV, using the CRISP program. To simulate these reactions, CRISP uses the Monte Carlo method through an intranuclear cascade model. Quase-elastic and baryonic resonance formation channels for the neutrino-nucleon interaction are considered. The total and differential particle emission cross-sections were obtained, obtaining a good agreement with the values reported by the MiniBooNE experiment. The influence of nuclear effects on the studied reactions, such as fermionic motion, the Pauli blocking mechanism, and the nucleonic separation energy, was shown. It was not possible to simultaneously reproduce the $ν_μ+ D$ and $ν_μ+ ^{12}C$ reactions using the same axial mass value. For the charged current quasi-elastic channel, $M_A = 0.95 \ GeV$ for the $ν_μ+ D$ reaction, and $M_A = 1.35 \ GeV$ for the $ν_μ+ ^{12}C$ reaction. This can be solved if one considers, in addition to the neutrino-nucleon interaction, the neutrino interaction with a pair of nucleons, just as we demonstrate in the last part of this work.

nucl-th↗

arXiv2017

Nuclear medium effects in muonic neutrino interaction with energies from 0.2 GeV to 1.5 GeV

Nuclear reactions induced by muon neutrino with energies in the range from 0.2 to 1.5 GeV in Monte Carlo calculations framework in the intra-nuclear cascade model are studied. This study was done by comparison between the available experimental data and theoretical values of total cross section, and the energy distribution of emitted lepton energy in the reaction muon neutrino-nucleus, using the targets: $^{12}$C, $^{16}$O, $^{27}$Al, $^{40}$Ar, $^{56}$Fe and $^{208}$Pb. A phenomenological toy model of primary neutrino-nucleon interaction gives a good agreement of our theoretical inclusive neutrino nucleus cross in comparison with the available experimental data. Some interesting results on the behavior of the cross section as function of 1p-1n and higher contributions are also sketched. The previous results on the percentage of fake events related in available experiments in $^{12}$C were expanded for the set studied nuclei. With the increase of mass target, the nuclear effects in the cross sections were observed along with the importance to take into account fake events in the reactions.

nucl-th↗

arXiv2007

Estimation of fuzzy anomalies in Water Distribution Systems

State estimation is necessary in diagnosing anomalies in Water Demand Systems (WDS). In this paper we present a neural network performing such a task. State estimation is performed by using optimization, which tries to reconcile all the available information. Quantification of the uncertainty of the input data (telemetry measures and demand predictions) can be achieved by means of robust estate estimation. Using a mathematical model of the network, fuzzy estimated states for anomalous states of the network can be obtained. They are used to train a neural network capable of assessing WDS anomalies associated with particular sets of measurements.

cs.NE↗

arXiv2005

Ga-induced atom wire formation and passivation of stepped Si(112)

We present an in-depth analysis of the atomic and electronic structure of the quasi one-dimensional (1D) surface reconstruction of Ga on Si(112) based on Scanning Tunneling Microscopy and Spectroscopy (STM and STS), Rutherford Backscattering Spectrometry (RBS) and Density Functional Theory (DFT) calculations. A new structural model of the Si(112)6 x 1-Ga surface is inferred. It consists of Ga zig-zag chains that are intersected by quasi-periodic vacancy lines or misfit dislocations. The experimentally observed meandering of the vacancy lines is caused by the co-existence of competing 6 x 1 and 5 x 1 unit cells and by the orientational disorder of symmetry breaking Si-Ga dimers inside the vacancy lines. The Ga atoms are fully coordinated, and the surface is chemically passivated. STS data reveal a semiconducting surface and show excellent agreement with calculated Local Density of States (LDOS) and STS curves. The energy gain obtained by fully passivating the surface calls the idea of step-edge decoration as a viable growth method toward 1D metallic structures into question.

cond-mat.other↗

arXiv2004

Barrier formation at metal/organic interfaces: dipole formation and the Charge Neutrality Level

The barrier formation for metal/organic semiconductor interfaces is analyzed within the Induced Density of Interface States (IDIS) model. Using weak chemisorption theory, we calculate the induced density of states in the organic energy gap and show that it is high enough to control the barrier formation. We calculate the Charge Neutrality Levels of several organic molecules (PTCDA, PTCBI and CBP) and the interface Fermi level for their contact with a Au(111) surface. We find an excellent agreement with the experimental evidence and conclude that the barrier formation is due to the charge transfer between the metal and the states induced in the organic energy gap.

cond-mat.mtrl-sci↗

arXiv2004

Dipole formation at metal/PTCDA interfaces: Role of the Charge Neutrality Level

The formation of a metal/PTCDA (3, 4, 9, 10-perylenetetracarboxylic dianhydride) interface barrier is analyzed using weak-chemisorption theory. The electronic structure of the uncoupled PTCDA molecule and of the metal surface is calculated. Then, the induced density of interface states is obtained as a function of these two electronic structures and the interaction between both systems. This induced density of states is found to be large enough (even if the metal/PTCDA interaction is weak) for the definition of a Charge Neutrality Level for PTCDA, located 2.45 eV above the highest occupied molecular orbital. We conclude that the metal/PTCDA interface molecular level alignment is due to the electrostatic dipole created by the charge transfer between the two solids.

cond-mat.mtrl-sci↗

arXiv2004

Formation of atom wires on vicinal silicon

The formation of atomic wires via pseudomorphic step-edge decoration on vicinal silicon surfaces has been analyzed for Ga on the Si(112) surface using Scanning Tunneling Microscopy and Density Functional Theory calculations. Based on a chemical potential analysis involving more than thirty candidate structures and considering various fabrication procedures, it is concluded that pseudomorphic growth on stepped Si(112), both under equilibrium and non-equilibrium conditions, must favor formation of Ga zig-zag chains rather than linear atom chains. The surface is non-metallic and presents quasi-one dimensional character in the lowest conduction band.

cond-mat.mtrl-sci↗

arXiv2003

Targeting qubit states using open-loop control

We present an open-loop (bang-bang) scheme which drives an open two-level quantum system to any target state, while maintaining quantum coherence throughout the process. The control is illustrated by a realistic simulation for both adiabatic and thermal decoherence. In the thermal decoherence regime, the control achieved by the proposed scheme is qualitatively similar, at the ensemble level, to the control realized by the quantum feedback scheme of Wang, Wiseman, and Milburn [Phys. Rev. A 64, #063810 (2001)] for the spontaneous emission of a two-level atom. The performance of the open-loop scheme compares favorably against the quantum feedback scheme with respect to robustness, target fidelity and transition times.

quant-ph↗

arXiv2003

Robust control of decoherence in realistic one-qubit quantum gates

We present an open loop (bang-bang) scheme to control decoherence in a generic one-qubit quantum gate and implement it in a realistic simulation. The system is consistently described within the spin-boson model, with interactions accounting for both adiabatic and thermal decoherence. The external control is included from the beginning in the Hamiltonian as an independent interaction term. After tracing out the environment modes, reduced equations are obtained for the two-level system in which the effects of both decoherence and external control appear explicitly. The controls are determined exactly from the condition to eliminate decoherence, i.e. to restore unitarity. Numerical simulations show excellent performance and robustness of the proposed control scheme.

quant-ph↗

arXiv1998

Microscopic mechanism for mechanical polishing of diamond (110) surfaces

Mechanically induced degradation of diamond, as occurs during polishing, is studied using total--energy pseudopotential calculations. The strong asymmetry in the rate of polishing between different directions on the diamond (110) surface is explained in terms of an atomistic mechanism for nano--groove formation. The post--polishing surface morphology and the nature of the polishing residue predicted by this mechanism are consistent with experimental evidence.

cond-mat.mtrl-sci↗