Search results for "C.M.M."
showing 10 items of 1066 documents
Prediction for magnetic moment of the muon informs a test of the standard model of particle physics
2021
A new first-principles computation of the effect that creates most uncertainty in calculations of the magnetic moment of the muon particle has been reported. The results might resolve a long-standing puzzle, but pose another conundrum. Fresh evidence in a longstanding puzzle of particle physics.
Type-II Supernovae and Neutrino Magnetic Moment
1998
The present solar and atmospheric neutrino data together with the LSND results and the presence of hot dark matter (HDM) suggest the existence of a sterile neutrino at the eV scale. We have reanalysed the effect of resonant {\sl sterile} neutrino conversions induced by neutrino magnetic moments in a type-II supernova. We analyse the implications of $\nu_e-\nu_s$ and $\bar{\nu}_e-\bar{\nu}_s$ ($\nu_s$ denotes sterile neutrino) conversions for the supernova shock re-heating, the detected $\bar\nu_e$ signal from SN1987A and the $r$-process nucleosynthesis hypothesis. Using reasonable magnetic field profiles we determine the sensitivity of these three arguments to the relevant neutrino paramete…
Microwave spectroscopy on heavy-fermion systems: probing the dynamics of charges and magnetic moments
2013
Investigating solids with light gives direct access to charge dynamics, electronic and magnetic excitations. For heavy fermions, one has to adjust the frequency of the probing light to the small characteristic energy scales, leading to spectroscopy with microwaves. We review general concepts of the frequency-dependent conductivity of heavy fermions, including the slow Drude relaxation and the transition to a superconducting state, which we also demonstrate with experimental data taken on UPd2Al3. We discuss the optical response of a Fermi liquid and how it might be observed in heavy fermions. Microwave studies with focus on quantum criticality in heavy fermions concern the charge response, …
Nature of Heavy Quasiparticles in Magnetically Ordered Heavy FermionsUPd2Al3andUPt3
2002
The optical conductivity of the heavy fermions $\mathrm{UPd}{}_{2}{\mathrm{Al}}_{3}$ and $\mathrm{UPt}{}_{3}$ has been measured in the energy range from 0.04 to 5 meV. In both compounds a well pronounced pseudogap of less than 1 meV develops in the optical response at low temperatures; we relate this to the antiferromagnetic ordering. From the energy dependence of the effective mass and scattering rate we conclude that the enhancement of the mass mainly occurs below the energy which is related to magnetic correlations between the local magnetic moments and the itinerant electrons. This implies that the magnetic order in these compounds is the prerequisite to the formation of the heavy quasi…
Evidence for Multiband Superconductivity in the Heavy Fermion CompoundUNi2Al3
2004
Epitaxial thin films of the heavy fermion superconductor UNi2Al3 with Tc(max)=0.98 K were investigated. The transition temperature Tc depends on the current direction which can be related to superconducting gaps opening at different temperatures. Also the influence of the magnetic ordering at TN approximately 5 K on R(T) is strongly anisotropic, indicating different coupling between the magnetic moments and itinerant charge carriers on the multisheeted Fermi surface. The upper critical field Hc2(T) suggests an unconventional spin-singlet superconducting state.
Neutron diffraction study of the heavy fermion superconductors UM2Al3(M=Pd, Ni)
1992
An elastic neutron scattering study was performed on the new superconducting heavy fermion systems UPd2Al3 and UNi2Al3. The neutron diffraction patterns reveal unambiguously long range antiferromagnetic order in UPd2Al3 with an ordered magnetic momentμ U = (0.85±0.03)μ B , which coexists with the superconducting state. This is by far the largestμ U value observed for any heavy fermion superconductor. For UNi2Al3, no long-range magnetic order could be observed for temperaturesT≧1.5 K, yielding an upper limit of the ordered moment of 0.2μ B .
Estimating the magnetic moment of microscopic magnetic sources from their magnetic field distribution in a layer of nitrogen-vacancy (NV) centres in …
2016
We have used a synthetic diamond with a layer of nitrogen-vacancy (NV) centres to image the magnetic field distributions of magnetic particles on the surface of the diamond. Magnetic field distributions of 4 µ m and 2 µ m ferromagnetic and 500 nm diameter superparamagnetic particles were obtained by measuring the position of the optically detected magnetic resonance peak in the fluorescence emitted by the NV centres for each pixel. We fitted the results to a model in order to determine the magnetic moment of the particles from the magnetic field image and compared the results to the measured magnetic moment of the particles. The best-fit magnetic moment differed from the value expected base…
Cosmological Applications of Extended Electromagnetism
2013
Extended electromagnetism (EE) has been applied to cosmology in various papers. In all of them, the zero order energy density of the EE vector field plays the same role as vacuum energy. Perturbations of this field have been studied by using different approaches. Firstly, some basic equations and ideas are summarized and, then, the CMBFAST code is used to calculate the cosmic microwave background angular power spectrum for appropriate values of the EE parameters. Comparisons of the resulting spectra with a good observational one compatible with WMAP7 (Wilkinson map anisotropy probe 7 years data) seem to be promising. We are currently looking for a set of parameters leading to the best fitti…
Probing the single-particle behavior above Sn132 via electromagnetic moments of Sb133,134 and N=82 isotones
2021
Magnetic and quadrupole moments of the $7/{2}^{+}$ ground state in $^{133}\mathrm{Sb}$ and the $({7}^{\ensuremath{-}})$ isomer in $^{134}\mathrm{Sb}$ have been measured by collinear laser spectroscopy to investigate the single-particle behavior above the doubly magic nucleus $^{132}\mathrm{Sn}$. The comparison of experimental data of the $7/{2}^{+}$ states in $^{133}\mathrm{Sb}$ and neighboring $N=82$ isotones to shell-model calculations reveals the sensitivity of magnetic moments to the splitting of the spin-orbit partners $\ensuremath{\pi}0{g}_{9/2}$ and $\ensuremath{\pi}0{g}_{7/2}$ across the proton shell closure at $Z=50$. In contrast, quadrupole moments of the $N=82$ isotones are insen…
European vestibular experiments on the Spacelab-1 mission: 4. Thresholds of perception of whole-body linear oscillation.
1986
Thresholds for the detection of linear oscillatory motion at 0.3 Hz in the X, Y and Z body axes were determined during the flight of Spacelab-1 and on the ground pre- and post-flight, using the method of limits with a single staircase procedure. Pre-flight, Z axis thresholds (mean 0.077 ms-2) were significantly higher than X and Y thresholds (mean 0.029 ms-2). Measures obtained on three crew members in-flight exhibited thresholds greater, by a factor of 1.5-4.3, than those obtained pre-flight. Post-flight, two crew members had significantly elevated X and Y axis thresholds whereas the other two crew members had lowered thresholds in X, Y and Z axes. In general, thresholds had returned to pr…