Search results for "Preces"
showing 10 items of 114 documents
Multiple points of view of heteronuclear NOE: long range vs short range contacts in pyrrolidinium based ionic liquids in the presence of Li salts.
2015
The nuclear Overhauser enhancement (NOE) is a powerful tool of NMR spectroscopy extensively used to gain structural information in ionic liquids (ILs). A general model for the distance dependence of intermolecular NOE in ILs was recently proposed showing that NOE spots beyond the first solvation shell and accounts for long-range effects. This conclusion prompted for a deep rethinking of the NOE data interpretation in ILs. In this paper we present an extensive and quantitative study of N-propyl-N-methyl pyrrolidinium bis(trifluoromethanesulfonyl)imide (PYR13TFSI), the homologue with bis(fluorosulfonyl)imide (PYR13FSI), and their mixtures with LiTFSI based on 1H-19F and 1H-7LiNOE correlation …
Structure characterization of hard materials by precession electron diffraction and automatic diffraction tomography: 6H-SiC semiconductor and Ni1+xT…
2012
Using a combination of automated diffraction tomography and precession electron diffraction techniques, quasi-kinematical electron diffraction data sets were collected from intermetallic Ni1+xTe1 embedded nanodomains and ion-thinned specimens of 6H–SiC semiconductor. Cell parameters and space groups were found automatically from the reconstructed 3D diffraction volume. The extracted intensities were used for fast ab initio structure determination by direct methods.
Pirmás pamahzibas tautas saimneezibâ [Pirmās pamācības tautas saimniecībā]
1895
Saturs: Ievads. Preču vērtība. Nauda un cena. Kapitāls. Kā darba spēks top par preci. Virsvērtība (peļņas tiesa). Kapitāla augšana.
Testing isotropy of the universe using the Ramsey resonance technique on ultracold neutron spins
2010
Physics at the Planck scale could be revealed by looking for tiny violations of fundamental symmetries in low energy experiments. In 2008, a sensitive test of the isotropy of the Universe using has been performed with stored ultracold neutrons (UCN), this is the first clock-comparison experiment performed with free neutrons. During several days we monitored the Larmor frequency of neutron spins in a weak magnetic field using the Ramsey resonance technique. An non-zero cosmic axial field, violating rotational symmetry, would induce a daily variation of the precession frequency. Our null result constitutes one of the most stringent tests of Lorentz invariance to date.
Constraining interactions mediated by axion-like particles with ultracold neutrons
2015
We report a new limit on a possible short range spin-dependent interaction from the precise measurement of the ratio of Larmor precession frequencies of stored ultracold neutrons and Hg199 atoms confined in the same volume. The measurement was performed in a ~1μT vertical magnetic holding field with the apparatus searching for a permanent electric dipole moment of the neutron at the Paul Scherrer Institute. A possible coupling between freely precessing polarized neutron spins and unpolarized nucleons of the wall material can be investigated by searching for a tiny change of the precession frequencies of neutron and mercury spins. Such a frequency change can be interpreted as a consequence o…
Gravitational depolarization of ultracold neutrons : comparison with data
2015
We compare the expected effects of so-called gravitationally enhanced depolarization of ultracold neutrons to measurements carried out in a spin-precession chamber exposed to a variety of vertical magnetic-field gradients. In particular, we have investigated the dependence upon these field gradients of spin depolarization rates and also of shifts in the measured neutron Larmor precession frequency. We find excellent qualitative agreement, with gravitationally enhanced depolarization accounting for several previously unexplained features in the data.
Measurement of the neutron electric form factor
2003
Abstract The neutron electric form factor GE,n has been measured at three different four-momentum transfer in a D(|e|→, e′|e|→)p experiment. Neutronwere detected in a recoil 0 polarimeter, using a spin precession method. We present the experiment and the status of data analysis.
Progress towards the first measurement of charm baryon dipole moments
2021
Electromagnetic dipole moments of short-lived particles are sensitive to physics within and beyond the Standard Model of particle physics but have not been accessible experimentally to date. To perform such measurements it has been proposed to exploit the spin precession of channeled particles in bent crystals at the LHC. Progress that enables the first measurement of charm baryon dipole moments is reported. In particular, the design and characterization on beam of silicon and germanium bent crystal prototypes, the optimization of the experimental setup, and advanced analysis techniques are discussed. Sensitivity studies show that first measurements of $\Lambda_c^+$ and $\Xi_c^+$ baryon dip…
Application of spin-exchange relaxation-free magnetometry to the Cosmic Axion Spin Precession Experiment
2018
The Cosmic Axion Spin Precession Experiment (CASPEr) seeks to measure oscillating torques on nuclear spins caused by axion or axion-like-particle (ALP) dark matter via nuclear magnetic resonance (NMR) techniques. A sample spin-polarized along a leading magnetic field experiences a resonance when the Larmor frequency matches the axion/ALP Compton frequency, generating precessing transverse nuclear magnetization. Here we demonstrate a Spin-Exchange Relaxation-Free (SERF) magnetometer with sensitivity $\approx 1~{\rm fT/\sqrt{Hz}}$ and an effective sensing volume of 0.1 $\rm{cm^3}$ that may be useful for NMR detection in CASPEr. A potential drawback of SERF-magnetometer-based NMR detection is …
Magnetic field uniformity in neutron electric dipole moment experiments
2019
© 2019 American Physical Society. Magnetic-field uniformity is of the utmost importance in experiments to measure the electric dipole moment of the neutron. A general parametrization of the magnetic field in terms of harmonic polynomial modes is proposed, going beyond the linear-gradients approximation. We review the main undesirable effects of nonuniformities: depolarization of ultracold neutrons and Larmor frequency shifts of neutrons and mercury atoms. The theoretical predictions for these effects were verified by dedicated measurements with the single-chamber neutron electric-dipole-moment apparatus installed at the Paul Scherrer Institute. ispartof: Physical Review A vol:99 issue:4 sta…