SPHERES, J\"ulich's High-Flux Neutron Backscattering Spectrometer at FRM II

SPHERES (SPectrometer with High Energy RESolution) is a third-generation neutron backscattering spectrometer, located at the 20 MW German neutron source FRM II and operated by the Juelich Centre for Neutron Science. It offers an energy resolution (fwhm) better than 0.65 micro-eV, a dynamic range of +-31 micro-eV, and a signal-to-noise ratio of up to 1750:1.Comment: 12 pages, 7 figures, 2 tables. Supplemental material consists of 3 pages, 2 figures, 2 table

Fußball, Euroball und andere Polyeder

Im Rahmen des Euroball-Projektes (41r-Hochpräzisions-y-Spektrometer) wurden inder ZAT 1 Untersuchungen durchgeführt, eine Kugeloberfläche möglichst gleichmäßig mitFlächen zu belegen . Einen solchen Körper nennt man Polyeder (Vielflächner).Für den Euroball muß das Polyeder folgende Forderungen erfüllen:• an jeder Ecke des Polyeders treffen drei Polygone (Vielecke) zusammen• die Anzahl verschiedenartiger Polygone soll möglichst klein sein• die Polygone sind kongruent (deckungsgleich)• die Polygonfläche soll möglichst wenig von der Fläche des umschreibendenKreises abweichenDiese Forderungen werden am besten von einem Polyedertyp erfüllt:das Polyeder mit I2 Pentagons und x-Hexagon

First result from the magic-PASTIS using large 3^{3} He SEOP-polarized GE180 doughnut cell

We report on the first results of the newly proposed and prototyped PASTIS coil set, enabling for XYZ polarization analysis on the future thermal time-of flight spectrometers. Our setup uses a wide-angle banana shaped 3He Neutron Spin Filter cell (NSF) to cover a large range of scattering solid angle. The design assures relative magnetic field gradients < 10-3 cm-1 and large solid angle areas not interrupted by either coils or supports. In the vertical direction nearly 40° are open and the blind spots in the horizontal scattering plane comprise only 3° in 180° due to the square X and Y compensation coils. We present the first results of the field mapping and relaxations time measurements using a large 3He SEOP polarized GE180 doughnut cell

in-situ 3 He SEOP polarizer for Thermal neutrons

In this article, we describe a neutron polarizer for a new time-of-flight neutron spectrometer with the polarization analysis TOPAS. This instrument will use the convergent focused incoming beam of thermal neutrons with energies up to 150 meV (wavelength down to 0.74Å). The polarizer employs a high opacity 3He neutron spin filter with continuous 3He polarization provided by two laser array bars frequency narrowed by an ultra-compact volume Bragg grating. The system was successfully prototyped, and tested. In the course of first experimental test at the polarized hot neutron diffractometer POLI at MLZ, neutron polarization of 97.6% was achieved for 0.895Å neutrons and kept constant during 30 days

Towards wide-angle neutron polarization analysis with a 3He spin filter for TOPAS and NEAT: Testing magic PASTIS on V20 at HZB

An XYZ polarization analysis solution has been developed for the new thermal time of amp; 64258;ight spectrometer TOPAS [1], to be operated in the coming east neutron guide hall at the MLZ. This prototype is currently being prepared to use on NEAT at HZB [2]. Polarization Analysis Studies on a Thermal Inelastic Spectrometer, commonly called PASTIS [3], is based on polarized 3He neutron spin amp; 64257;lters and an XYZ amp; 64257;eld con amp; 64257;guration for the sample environment and a polarization preserving neutron guide amp; 64257;eld. The complete system was designed to provide adiabatic transport of the neutron polarization to the sample position on TOPAS while maintaining the homogeneity of the XYZ amp; 64257;eld. This complete system has now been tested on the polarized time of amp; 64258;ight ESS test beam line V20 at HZB [4]. We present results of this test and the next steps forwar

SPHERS, Jïlich's high-flux neutron backscattering spectrometer at FRM II

SPHERES is a third-generation neutron backscattering spectrometer, located at the 20 MW German neutron source FRM II and operated by the Jülich Centre for Neutron Science. It offers an energy resolution (fwhm) better than 0.65 μeV, a dynamic range of ± 31 μeV, and a signal-to-noise ratio of up to 1750:1