Search results for "atomic physics"
showing 10 items of 5530 documents
The branching ratio of intercombination $A^1\Sigma^+\sim b^3\Pi\to a^3\Sigma^+/X^1\Sigma^+$ transitions in the RbCs molecule: measurements and calcul…
2020
We observed the $A^1\Sigma^+\sim b^3\Pi\to a^3\Sigma^+/X^1\Sigma^+$ laser-induced fluorescence (LIF) spectra of the RbCs molecule excited from the ground $X^1\Sigma^+$ state by the Ti:Sapphire laser. The LIF radiation from the common perturbed levels of the singlet-triplet $A\sim b$ complex was recorded by the Fourier-transform (FT) spectrometer with the instrumental resolution of 0.03~cm$^{-1}$. The relative intensity distribution in the rotationally resolved $A\sim b\to a^3\Sigma^+(v_a)/X^1\Sigma^+(v_X)$ progressions was measured, and their branching ratio was found to be about of 1$\div$5$ \times$10$^{-4}$ in the bound region of the $a^3\Sigma^+$ and $X^1\Sigma^+$ states. The experiment …
ATLAS data quality operations and performance for 2015-2018 data-taking
2020
The ATLAS detector at the Large Hadron Collider reads out particle collision data from over 100 million electronic channels at a rate of approximately 100 kHz, with a recording rate for physics events of approximately 1 kHz. Before being certified for physics analysis at computer centres worldwide, the data must be scrutinised to ensure they are clean from any hardware or software related issues that may compromise their integrity. Prompt identification of these issues permits fast action to investigate, correct and potentially prevent future such problems that could render the data unusable. This is achieved through the monitoring of detector-level quantities and reconstructed collision ev…
Observation and Measurement of Forward Proton Scattering in Association with Lepton Pairs Produced via the Photon Fusion Mechanism at ATLAS
2020
The observation of forward proton scattering in association with lepton pairs (eþe− þ p or μþμ− þ p) produced via photon fusion is presented. The scattered proton is detected by the ATLAS Forward Proton spectrometer, while the leptons are reconstructed by the central ATLAS detector. Proton-proton collision data recorded in 2017 at a center-of-mass energy of ffiffiffi s p ¼ 13 TeV are analyzed, corresponding to an integrated luminosity of 14.6 fb−1. A total of 57 (123) candidates in the ee þ p (μμ þ p) final state are selected, allowing the background-only hypothesis to be rejected with a significance exceeding 5 standard deviations in each channel. Proton-tagging techniques are introduced f…
Measurement of the Lund jet plane using charged particles in 13 TeV proton-proton collisions with the ATLAS detector
2020
The prevalence of hadronic jets at the LHC requires that a deep understanding of jet formation and structure is achieved in order to reach the highest levels of experimental and theoretical precision. There have been many measurements of jet substructure at the LHC and previous colliders, but the targeted observables mix physical effects from various origins. Based on a recent proposal to factorize physical effects, this Letter presents a double-differential cross-section measurement of the Lund jet plane using 139 fb−1 of √s=13 TeV proton-proton collision data collected with the ATLAS detector using jets with transverse momentum above 675 GeV. The measurement uses charged particles to ac…
Atomic physics, optical technologies, and medical physics: Abstracts book, 16.-17.02.2023., Riga
2023
81h International Scientific Conference of the University of Latvia Section ‘Atomic physics, optical technologies and medical physics’ will be held by Institute of Atomic Physics and Spectroscopy (IAPS) on 16-17.02.2023. The section will present the recent results, achieved by IAPS researchers and the IAPS partners in the following research fields: optical phenomena in gas, liquid, solid state and biological samples, optical methods for diagnostics, chemical analysis and optical sensor technologies, quantum optics and telecommunication, modelling, novel nanomaterials and their biomedical applications. Total 23 abstracts.
Atomic, molecular and optical physics section: (LU FMOF Laser Centre section): Book of Abstracts : 31st of January 2023, 10.00 AM, online
2023
This book of abstracts is made for the Laser Centre section "Atomic, molecular and optical physics section", that occurred as a part of the 81st International Scientific Conference of the University of Latvia. This section was organized by the staff of Laser Centre of the University of Latvia and was held on the 31st of January, 2023. The book of abstracts contains contributions from researchers working on various light-matter interaction problems from all four laboratories of the Laser Center - Atomic and Molecular Physics Laboratory, Molecule Optical Polarization Laboratory, Color centre laboratory and Laboratory of Astrospectroscopy.
Atomic physics, optical technologies and medical physics, 10-11.02.2022.,Riga
2022
80th International Scientific Conference of the University of Latvia Section ‘Atomic physics, optical technologies and medical physics’ will be held by Institute of Atomic Physics and Spectroscopy (IAPS) on 10-11.02.2022. The section will present the recent results, achieved by IAPS researchers and the IAPS partners in the following research fields: optical phenomena in gas, liquid, solid state and biological samples, optical methods for diagnostics, chemical analysis and optical sensor technologies, quantum optics and telecommunication, modelling, novel nanomaterials and their biomedical applications. Total 27 abstracts.
A theoretical study of the 1B2u and 1B1u vibronic bands in benzene
2000
The two lowest bands, 1B2u and 1B1u, of the electronic spectrum of the benzene molecule have been studied theoretically using a new method to compute vibronic excitation energies and intensities. The complete active space (CAS) self-contained field (SCF) method (with six active π-orbitals) was used to compute harmonic force field for the ground state and the 1B2u and 1B1u electronic states. A linear approximation has been used for the transition dipole as a function of the nuclear displacement coordinates. Derivatives of the transition dipole were computed using a variant of the CASSCF state interaction method. Multiconfigurational second-order perturbation theory (CASPT2) was used to obtai…
Quantum-chemical determination of Born–Oppenheimer breakdown parameters for rotational constants: the open-shell species CN, CO+ and BO
2013
The quantum-chemical protocol for computing Born-Oppenheimer breakdown corrections to rotational constants in the case of diatomic molecules is extended to open-shell species. The deviation from the Born-Oppenheimer equilibrium rotational constant is obtained by considering three contributions: the adiabatic correction to the equilibrium bond distance, the electronic contribution to the moment of inertia requiring the computation of the rotational g-tensor, and the so-called Dunham correction. Values for the Born-Oppenheimer breakdown parameters of CN, CO+, and BO in their (2)sigma(+) electronic ground states are reported based on coupled-cluster calculations of the involved quantities and …
Multiple scattering approach for two-electron resonant emission studied by angle-resolved coincidence spectroscopy.
2008
International audience; We have developed a generalization of the multiple-scattering formalism to deal with Auger-photoelectron coincidence spectroscopy APECS in the solid state. We have merged the exact atomic treatment of the angular correlations between the two electrons and the single-particle approach, on which the multiplescattering description of condensed matter relies. This allows the recovering, even in extended systems, of the entangled form of the electron-pair wave function characterizing the coincidence angular diffraction pattern. In the atomic limit our formalism correctly reproduces the cross section, as calculated within the statistical-tensors approach, usually employed …