Search results for "Spins"
showing 10 items of 257 documents
Nuclear moments of strongly deformed strontium isotopes
1990
Nuclear spins, moments and mean square charge radii of78–100Sr have been obtained by fast ion-beam collinear laserspectroscopy. The experiments performed at ISOLDE have been extended to include99Sr, measured by a non-optical detection scheme with a two-step optical pumping sequence. The results for the strongly deformed isotopes are discussed in the frame of the particle-plus-deformed core model.
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.
Extreme nuclear magnetic resonance: Zero field, single spins, dark matter….
2019
An unusual regime for liquid-state nuclear magnetic resonance (NMR) where the magnetic field strength is so low that the $J$-coupling (intramolecular spin-spin) interactions dominate the spin Hamiltonian opens a new paradigm with applications in spectroscopy, quantum control, and in fundamental-physics experiments, including searches for well-motivated dark-matter candidates. An interesting possibility is to bring this kind of "extreme NMR" together with another one---single nuclear spin detected with a single-spin quantum sensor. This would enable single-molecule $J$-spectroscopy.
In-beam spectroscopy of224Th
1986
A rotational band with states of alternating parity has been populated in224Th via the208Pb(18O, 2n) reaction. Spins up to Iπ=10>+ (11−) are identified. Stretched El and E2 transitions compete in the deexcitation, the average ratio of the reduced transition probabilities being B(E1)/B(E2)=(1.5±0.4)×10−6 fm−2. This ratio implies that224Th has one of the largest intrinsic electric dipole moments observed so far.
Nuclear moments and charge radii of rare-earth isotopes studied by collinear fast-beam laser spectroscopy
1983
The collinear fast-beam laser technique is being used to measure systematically hyperfine structures and isotope shifts of unstable nuclides in the rare-earth region. This brief report gives a general survey of the results obtained for the even-Z elements64Gd,66Dy,68Er and70Yb, with emphasis on the nuclear spins and moments. They allow a rather complete mapping of the single-particle structure and the development of nuclear deformation in the N > 82 region. The spins, magnetic moments and spectroscopic quadrupole moments of159–169Yb are presented in detail.
Hyperfine structure and isotope shift investigations in $^{202-222}$Rn for the study of nuclear structure beyond Z = 82
1986
The hyperfine structure (hfs) and isotope shift (IS) in the isotopic chain of the radioactive element radon have been studied for the first time. The measurements were carried out by collinear fast-beam laser spectroscopy at the mass separator facility ISOLDE at CERN. The IS between 16 isotopes in the mass range 202≦A≦222 and the hfs of 7 odd-A isotopes were determined in the transitions 7s [3/2]2-7p [5/2]3 (745 nm) of Rn I. The nuclear spins and moments, as well as the observed inversion of the odd-even staggering for218–222Rn, can be associated with the effects of octupole instability around N=134.
Nuclear ground state properties from optical investigations
1986
Recent progress in on-line techniques of laser spectroscopy applied to nuclei far off stability is reviewed. The results concern nuclear spins, moments and charge radii, determined from hyperfine structure and isotope shift of atomic transitions. Examples of large core polarizations in the Cd-In-Sn region, derived from isotope shifts, and the octupole deformation in the Ra region, derived from ground state spins and magnetic moments, are discussed.
Zero- to Ultralow-Field Nuclear Magnetic Resonance $J$-Spectroscopy with Commercial Atomic Magnetometers
2019
Zero- to ultralow-field nuclear magnetic resonance (ZULF NMR) is an alternative spectroscopic method to high-field NMR, in which samples are studied in the absence of a large magnetic field. Unfortunately, there is a large barrier to entry for many groups, because operating the optical magnetometers needed for signal detection requires some expertise in atomic physics and optics. Commercially available magnetometers offer a solution to this problem. Here we describe a simple ZULF NMR configuration employing commercial magnetometers, and demonstrate sufficient functionality to measure samples with nuclear spins prepolarized in a permanent magnet or initialized using parahydrogen. This opens …
Sensitivity enhancement in pulse EPR distance measurements
2004
Established pulse EPR approaches to the measurement of small dipole-dipole couplings between electron spins rely on constant-time echo experiments to separate relaxational contributions from dipolar time evolution. This requires a compromise between sensitivity and resolution to be made prior to the measurement, so that optimum data are only obtained if the magnitude of the dipole-dipole coupling is known beforehand to a good approximation. Moreover, the whole dipolar evolution function is measured with relatively low sensitivity. These problems are overcome by a variable-time experiment that achieves suppression of the relaxation contribution by reference deconvolution. Theoretical and exp…
Evidence for Increased neutron and proton excitations between 51−63 Mn
2015
The hyperfine structures of the odd-even 51−63Mnatoms (N=26 −38) were measured using bunched beam collinear laser spectroscopy at ISOLDE, CERN. The extracted spins and magnetic dipole moments have been compared to large-scale shell-model calculations using different model spaces and effective interactions. In the case of 61,63Mn, the results show the increasing importance of neutron excitations across the N=40subshell closure, and of proton excitations across the Z=28shell gap. These measurements provide the first direct proof that proton and neutron excitations across shell gaps are playing an important role in the ground state wave functions of the neutron-rich Mn isotopes. publisher: Els…