A new method to determine the spin tune is described and tested. In an ideal planar magnetic ring, the spin tune-defined as the number of spin precessions per turn-is given by ν s ¼ γG (γ is the Lorentz factor, G the gyromagnetic anomaly). At 970 MeV=c, the deuteron spins coherently precess at a frequency of ≈120 kHz in the Cooler Synchrotron COSY. The spin tune is deduced from the up-down asymmetry of deuteron-carbon scattering. In a time interval of 2.6 s, the spin tune was determined with a precision of the PRL 115, 094801 (2015) P H Y S I C A L
Four-point measurements using a multitip scanning tunneling microscope are carried out in order to determine surface and step conductivities on Si(111) surfaces. In a first step, distance-dependent four-point measurements in the linear configuration are used in combination with an analytical three-layer model for charge transport to disentangle the 2D surface conductivity from nonsurface contributions. A termination of the Si(111) surface with either Bi or H results in the two limiting cases of a pure 2D or 3D conductance, respectively. In order to further disentangle the surface conductivity of the step-free surface from the contribution due to atomic steps, a square four-probe configuration is applied as a function of the rotation angle. In total, this combined approach leads to an atomic step conductivity of σ(step)=(29±9) Ω(-1) m(-1) and to a step-free surface conductivity of σ(surf)=(9±2)×10(-6) Ω(-1)/□ for the Si(111)-(7×7) surface.
NMR Mandhalas (Magnetic Arrangement for Novel Discrete Halbach LAyout) are arrays of identically shaped magnets in a Halbach-type arrangement. They provide a simple and cost-effective way to generate high magnetic fields for mobile applications, for example, in magnetic resonance. Based on the introductory publication by Raich and Blü mler (Concepts Magn Reson 2004;23B:16-25), we extend the notion of Mandhalas from cube-shaped magnets to polygonal and cylindrical ones and present construction guidelines for the stacking of such rings to generate homogeneous magnetic fields over larger volumes. For this purpose, we present formulas and numerical values based on a dipole approach to calculate the flux density of single rings and composed 3D systems and compare to corresponding results obtained by 3D boundary element method calculations. As an application of the approach presented here, we constructed prototypes.
The conventional Wien filter is a device with orthogonal static magnetic and electric fields, often used for velocity separation of charged particles. Here we describe the electromagnetic design calculations for a novel waveguide RF Wien filter that will be employed to solely manipulate the spins of protons or deuterons at frequencies of about 0.1 to 2 MHz at the COoler SYnchrotron COSY at Jülich. The device will be used in a future experiment that aims at measuring the proton and deuteron electric dipole moments, which are expected to be very small. Their determination, however, would have a huge impact on our understanding of the universe.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.