A5003944801- Atomic and Subatomic Physics Research
- Quantum, superfluid, helium dynamics
- Nuclear Physics and Applications
- Advanced NMR Techniques and Applications
- Cold Atom Physics and Bose-Einstein Condensates
- Advanced MRI Techniques and Applications
- Physics of Superconductivity and Magnetism
- Magnetic properties of thin films
- Quantum optics and atomic interactions
- High-pressure geophysics and materials
- Radiation Detection and Scintillator Technologies
- Spectroscopy and Quantum Chemical Studies
- Magnetic Properties and Synthesis of Ferrites
- Advanced Frequency and Time Standards
- Superconducting Materials and Applications
- Magnetic and transport properties of perovskites and related materials
- Fusion materials and technologies
- Nuclear reactor physics and engineering
- Dark Matter and Cosmic Phenomena
- Magneto-Optical Properties and Applications
- Membrane-based Ion Separation Techniques
- Advanced Condensed Matter Physics
- Iron oxide chemistry and applications
- Combustion and Detonation Processes
- Multiferroics and related materials
Forschungszentrum Jülich
2015-2024
Heinz Maier-Leibnitz Zentrum
2013-2024
European Spallation Source
2020
Institut Laue-Langevin
2006-2009
University of Wisconsin–Madison
2002-2007
We demonstrate spin-exchange optical pumping of 3He using a "hybrid" K-Rb vapor mixture. The Rb atoms absorb light from standard laser at 795 nm, then collisionally polarize the potassium atoms. Spin-exchange collisions K and transfer angular momentum to with much greater efficiency than Rb-3He. For K-rich vapor, hybrid approaches 1/4, an order magnitude achieved by pure pumping. present first measurements actual photon efficiencies (polarized nuclei produced per absorbed photon), show that...
The KWS-1 small-angle neutron scattering (SANS) instrument operated by the Jülich Centre for Neutron Science (JCNS) at research reactor FRM II of Heinz Maier-Leibnitz Zentrum in Garching near Munich has been recently upgraded. was updated, from its active collimation apertures to detector cabling. Most parts were installed first time, including a broadband polarizer, large-cross-section radio-frequency spin flipper, chopper and lenses. A custom-designed hexapod sample position allows heavy...
An overview is provided of the 15 neutron beam instruments making up initial instrument suite European Spallation Source (ESS), and being made available to user community. The ESS source consists a high-power accelerator target station, providing unique long-pulse time structure slow neutrons. design considerations behind structure, moderator geometry layout are presented. 15-instrument two small-angle instruments, reflectometers, an imaging beamline, single-crystal diffractometers; one for...
We have studied the efficiency of spin-exchange optical pumping (SEOP) in cells that contain either pure rubidium, mixtures rubidium and potassium, or potassium. Optical was performed with spectrally narrowed diode array lasers operating at wavelength Rb $5{s}_{1∕2}\ensuremath{-}5{p}_{1∕2}$ transition $(795\phantom{\rule{0.3em}{0ex}}\mathrm{nm})$ K $4{s}_{1∕2}\ensuremath{-}4{p}_{1∕2}$ $(770\phantom{\rule{0.3em}{0ex}}\mathrm{nm})$. Calculations expected are shown for practical conditions...
A versatile and portable magnetically shielded room with a field of (700 ± 200) pT within central volume 1 m × gradient less than 300 pT/m, achieved without any external stabilization or compensation, is described. This performance represents more hundredfold improvement the state art for two-layer magnetic shield provides an environment suitable next generation precision experiments in fundamental physics at low energies; particular, searches electric dipole moments systems tests...
We report results of a new technique to measure the electric dipole moment $^{129}\mathrm{Xe}$ with $^{3}\mathrm{He}$ comagnetometry. Both species are polarized using spin-exchange optical pumping, transferred measurement cell, and transported into magnetically shielded room, where SQUID magnetometers detect free precession in applied magnetic fields. The result from one week campaign 2017 2.5 2018, combined detailed study systematic effects, is...
MARIA (magnetism reflectometer with high incident angle) is a world class vertical sample dedicated to the investigation of thin films in fields magnetism, soft matter and biology. The elliptical vertically focusing guide allows one measure small samples typical size 1 × cm very efficiently. double-bounce polarizer situ pumped 3He SEOP (spin-exchange optical pumping) neutron spin filter cell for analysing polarization reflected beam can be moved into seconds. polarized flux amounts 5 107 n...
Based on measurements of the temperature dependence 3He relaxation in a wide range spin-exchange optical pumping cells, we report evidence for previously unrecognized surface process. The rate was found to be linearly proportional alkali-metal density with slope that exceeds rate, which limits polarization current applications, including neutron spin filters, polarized targets, and gas magnetic resonance imaging. We find magnitude this excess can vary widely between variation is larger cells...
We have obtained improvement in the 3He polarization achievable by spin-exchange optical pumping (SEOP). These results were primarily large neutron spin filter cells using diode bar lasers spectrally narrowed with chirped volume holographic gratings. As compared to our past diffraction gratings, we observed between 5% and 11% fractional increase PHe. also report a comparable PHe for two small cells, which would not expected an from improved laser performance. In particular, prior extensive...
Potassium hydroxide (KOH) doped polybenzimidazole (PBI) membranes are investigated as compelling candidates for water electrolysis applications, drastically reducing the ohmic losses in contrast to thick ZrO2 based diaphragms. Using small angle neutron scattering (SANS) we have found that structure of (KOH doped) PBI changes with doping time on a minute scale, and development is highly dependent KOH concentration. This data correlated macroscopic measurements membrane swelling resulting from...
Spin-exchange rate coefficients for Rb-${}^{3}\mathrm{He}$ are measured using three different methods. Two methods, Rb repolarization and balance, require no assumption about the nature of ${}^{3}\mathrm{He}$ wall relaxation agree well; we find spin-exchange $6.7\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}20}{\mathrm{cm}}^{3}/\mathrm{s}$ $6.8\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}20}{\mathrm{cm}}^{3}/\mathrm{s}.$ These results with a recent measurement Baranga...
We have produced 70%–75% 3He polarization by spin-exchange optical pumping in cells ≈100 cm3 volume. The achieved is consistent with known and spin-relaxation rates, but only when the recently discovered temperature dependence of relaxation included. Absolute measurements were performed using two different methods laboratories. results obtained either a spectrally narrowed laser or one type broadband laser. Based on tests several larger at pressures near 1 bar, we find that power required to...
We describe a method to frequency narrow multielement high-power diode bars. Using commercial 60-W, 49-element, 1-cm-long array bar at 795 nm running 45 W, we the linewidth from 1000 64 GHz with only loss of 33% in output power. The resulting laser light is well suited for spin-exchange optical pumping noble gas nuclei.
In a strong magnetic field, the cores of nanoparticles grow because realignment surrounding spins, challenging commonly held assumption constant nanoparticle moment.
We present temperature-dependent measurements of the EPR frequency shifts for Na, K, and Rb interacting with polarized $^{3}\mathrm{He}$. K Na were measured via comparison (well known at low temperatures) in $\mathrm{Na}\ensuremath{-}\mathrm{Rb}\ensuremath{-}^{3}\mathrm{He}$ $\mathrm{K}\ensuremath{-}\mathrm{Rb}\ensuremath{-}^{3}\mathrm{He}$ spin-exchange cells. The lowered vapor pressure these ``hybrid'' cells also allowed us to extend temperature dependence up...
We investigate the spin rotational structure of magnetic skyrmions in a tetragonal polar magnet VOSe2O5 via polarized small-angle neutron scattering (SANS). Spin polarization analysis scattered neutrons provides consistent evidence for cycloidal modulation all incommensurate phases at zero and non-zero field along c axis, including triangular skyrmion-lattice phase. In vicinity skyrmion phase, we performed extensive SANS measurements to unravel field-induced phase (IC-2 state). discuss...
Circularly polarized light propagating at an angle to the external magnetic field does not optically pump atoms full transparency under conditions common spin-exchange optical pumping experiments. This causes excess absorption of that can significantly reduce efficiency process even for angles a few degrees.