Radiation for laser-driven rescattering near the ultimate high-energy cutoff: The single-atom response and bremsstrahlung limit

AbstractSingle-atom catalysts (SACs) are promising candidates to catalyze electrochemical CO2 reduction (ECR) due to maximized atomic utilization. However, products are usually limited to CO instead of hydrocarbons or oxygenates due to unfavorable high energy barrier for further electron transfer on synthesized single atom catalytic sites. Here we report a novel partial-carbonization strategy to modify the electronic structures of center atoms on SACs for lowering the overall endothermic energy of key intermediates. A carbon-dots-based SAC margined with unique CuN2O2 sites was synthesized for the first time. The introduction of oxygen ligands brings remarkably high Faradaic efficiency (78%) and selectivity (99% of ECR products) for electrochemical converting CO2 to CH4 with current density of 40 mA·cm-2 in aqueous electrolytes, surpassing most reported SACs which stop at two-electron reduction. Theoretical calculations further revealed that the high selectivity and activity on CuN2O2 active sites are due to the proper elevated CH4 and H2 energy barrier and fine-tuned electronic structure of Cu active sites.

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ON ESTIMATING THE HIGH-ENERGY CUTOFF IN THE X-RAY SPECTRA OF BLACK HOLES VIA REFLECTION SPECTROSCOPY

The Astrophysical Journal ◽

10.1088/2041-8205/808/2/l37 ◽

2015 ◽

Vol 808 (2) ◽

pp. L37 ◽

Cited By ~ 25

Author(s):

Javier A. García ◽

Thomas Dauser ◽

James F. Steiner ◽

Jeffrey E. McClintock ◽

Mason L. Keck ◽

...

Keyword(s):

Black Holes ◽

High Energy ◽

Reflection Spectroscopy ◽

X Ray ◽

Energy Cutoff

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A simple optical system delivering a tunable micrometer pink beam that can compensate for heat-induced deformations

Journal of Synchrotron Radiation ◽

10.1107/s1600577515006566 ◽

2015 ◽

Vol 22 (4) ◽

pp. 930-935 ◽

Cited By ~ 1

Author(s):

Ruben Reininger ◽

Zunping Liu ◽

Gilles Doumy ◽

Linda Young

Keyword(s):

Optical System ◽

Heat Load ◽

Optical Element ◽

High Energy ◽

Angle Of Incidence ◽

Optical Elements ◽

Source Distance ◽

Energy Cutoff ◽

Working Distance ◽

Photon Source

The radiation from an undulator reflected from one or more optical elements (usually termed `pink-beam') is used in photon-hungry experiments. The optical elements serve as a high-energy cutoff and for focusing purposes. One of the issues with this configuration is maintaining the focal spot dimension as the energy of the undulator is varied, since this changes the heat load absorbed by the first optical element. Finite-element analyses of the power absorbed by a side water-cooled mirror exposed to the radiation emitted by an undulator at the Advanced Photon Source (APS) and at the APS after the proposed upgrade (APSU) reveals that the mirror deformation is very close to a convex cylinder creating a virtual source closer to the mirror than the undulator source. Here a simple optical system is described based on a Kirkpatrick–Baez pair which keeps the focus size to less than 2 µm (in the APSU case) with a working distance of 350 mm despite the heat-load-induced change in source distance. Detailed ray tracings at several photon energies for both the APS and APSU show that slightly decreasing the angle of incidence on the mirrors corrects the change in the `virtual' position of the source. The system delivers more than 70% of the first undulator harmonic with very low higher-orders contamination for energies between 5 and 10 keV.

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On Measuring the Variation of High-energy Cutoff in Active Galactic Nuclei

The Astrophysical Journal ◽

10.3847/1538-4357/aacf92 ◽

2018 ◽

Vol 863 (1) ◽

pp. 71 ◽

Cited By ~ 2

Author(s):

Ji-Xian Zhang ◽

Jun-Xian Wang ◽

Fei-Fan Zhu

Keyword(s):

Active Galactic Nuclei ◽

Galactic Nuclei ◽

High Energy ◽

Energy Cutoff

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Ultrahigh Energy Cosmic-ray Accelerators

Symposium - International Astronomical Union ◽

10.1017/s0074180900163053 ◽

2000 ◽

Vol 195 ◽

pp. 303-310

Author(s):

A. V. Olinto

Keyword(s):

Angular Distribution ◽

Neutron Star ◽

Cosmic Rays ◽

Cosmic Ray ◽

High Energy ◽

Ultrahigh Energy ◽

Recent Proposal ◽

Alternative Models ◽

Isotropic Distribution ◽

Energy Cutoff

The surprising lack of a high energy cutoff in the cosmic ray spectrum at the highest energies, together with an apparently isotropic distribution of arrival directions, have strongly challenged most models proposed for the acceleration of ultrahigh energy cosmic rays. Young neutron star winds may be able to explain the mystery. We discuss this recent proposal after summarizing the observational challenge and plausible acceleration sites. Young neutrons star winds differ from alternative models in the predictions for composition, spectrum, and angular distribution, which will be tested in future experiments.

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TAMM-DANCOFF DEFORMATION OF BOSONIC OSCILLATOR ALGEBRAS

Modern Physics Letters A ◽

10.1142/s0217732393003457 ◽

1993 ◽

Vol 08 (39) ◽

pp. 3727-3734 ◽

Cited By ~ 25

Author(s):

S. CHATURVEDI ◽

V. SRINIVASAN ◽

R. JAGANNATHAN

Keyword(s):

High Energy ◽

Oscillator Algebra ◽

Energy Cutoff ◽

Similar Deformation ◽

Bosonic Oscillator ◽

Oscillator Algebras

The Tamm-Dancoff (TD) deformation of the boson oscillator incorporates a high energy cutoff in its spectrum. It is found that one can obtain a similar deformation of any generalized bosonic oscillator algebra. The Hopf (or ‘quantum’) algebraic aspects of the TD-deformation are discussed. Examples are given.

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Analyzing Ca-41 sample at 1E-15 abundance level with cold atom trap techniques

10.5194/egusphere-egu21-1959 ◽

2021 ◽

Author(s):

Tian Xia ◽

Tong-Yan Xia ◽

Wei-Wei Sun ◽

Wei Jiang ◽

Zheng-Tian Lu

Keyword(s):

Trace Analysis ◽

High Energy ◽

Single Atom ◽

Resonance Ionization ◽

Ionization Mass ◽

Capture Process ◽

Specific Element ◽

Atom Trap ◽

Natural Isotopic Abundance ◽

Exposure Ages

On earth, Calcium-41 is produced as a cosmogenic isotope via neutron capture process, leaving a natural isotopic abundance of 10-15 on earth surface. Calcium is also of vital importance for the metabolism of biological organisms. Consequently, analysis of the long lived radioactive isotope Calcium-41 is of great importance in geoscience, archeology and life sciences. The half-life of Calcium-41 is 1.03 x 105 years. It is a good candidate in dating rock and bone samples ranging from 50,000 to 1,000,000 years old.The available techniques for trace analysis of Calcium-41 include accelerator mass spectrometry (AMS) and resonance ionization mass spectroscopy (RIMS). The detection limit of RIMS is on the level of 10-11 due to the interference of Potassium-41, which is difficult to remove from the sample. The analysis with high-energy AMS is more expensive than the table top apparatus, and it also faces similar problem as RIMS method.We develop an atom trap trace analysis(ATTA) apparatus for Calcium-41 analysis to the sensitivity of 10-15 abundance level by one hour of single atom counting. ATTA uses laser tuned at the resonant wavelength for a specific element and isotope to slow down and capture single atom by fluorescence radiation. It has a very high selectivity of element and isotope, which is more advantageous than AMS and RIMS to avoid isobar interference. ATTA has been used in analysis of Krypton-81, Argon-39 dating of the hydrological samples. This work on high sensitivity Calcium-41 analysis is very promising in dating the geochemical sample to determine the exposure ages of rocks or in cosmochemistry for investigations on terrestrial ages.

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QUANTUM ANTI-DE SITTER SPACE AT ROOTS OF UNITY

International Journal of Modern Physics B ◽

10.1142/s0217979200002041 ◽

2000 ◽

Vol 14 (22n23) ◽

pp. 2499-2501

Author(s):

HAROLD STEINACKER

Keyword(s):

Hilbert Spaces ◽

Scalar Fields ◽

De Sitter Space ◽

High Energy ◽

Roots Of Unity ◽

De Sitter ◽

Algebra Of Functions ◽

Energy Cutoff ◽

Star Structure

An algebra of functions on q-deformed Anti-de Sitter space [Formula: see text] with star-structure is defined for roots of unity, which is covariant under Uq(so(2, D-1)). The scalar fields have an intrinsic high-energy cutoff, and arise most naturally on products of the quantum AdS space with a classical sphere. Hilbert spaces of scalar fields are constructed.

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Evaluation of Monte Carlo tools for high energy atmospheric physics

Geoscientific Model Development ◽

10.5194/gmd-9-3961-2016 ◽

2016 ◽

Vol 9 (11) ◽

pp. 3961-3974 ◽

Cited By ~ 7

Author(s):

Casper Rutjes ◽

David Sarria ◽

Alexander Broberg Skeltved ◽

Alejandro Luque ◽

Gabriel Diniz ◽

...

Keyword(s):

Monte Carlo ◽

Gamma Ray ◽

High Energy ◽

Atmospheric Physics ◽

Computational Performance ◽

Electron Positron ◽

Custom Made ◽

Electric And Magnetic Fields ◽

Energy Cutoff ◽

High Energy Particles

Abstract. The emerging field of high energy atmospheric physics (HEAP) includes terrestrial gamma-ray flashes, electron–positron beams and gamma-ray glows from thunderstorms. Similar emissions of high energy particles occur in pulsed high voltage discharges. Understanding these phenomena requires appropriate models for the interaction of electrons, positrons and photons of up to 40 MeV energy with atmospheric air. In this paper, we benchmark the performance of the Monte Carlo codes Geant4, EGS5 and FLUKA developed in other fields of physics and of the custom-made codes GRRR and MC-PEPTITA against each other within the parameter regime relevant for high energy atmospheric physics. We focus on basic tests, namely on the evolution of monoenergetic and directed beams of electrons, positrons and photons with kinetic energies between 100 keV and 40 MeV through homogeneous air in the absence of electric and magnetic fields, using a low energy cutoff of 50 keV. We discuss important differences between the results of the different codes and provide plausible explanations. We also test the computational performance of the codes. The Supplement contains all results, providing a first benchmark for present and future custom-made codes that are more flexible in including electrodynamic interactions.

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