Neutron Spin Echo Spectrometer

NSE |  BL-15 | SNS

Mission Statement

SNS-NSE is an ultrahigh resolution neutron spectrometer for characterizing the slow dynamics of soft condensed matter.

Instrument Description

SNS-NSE is a time-of-flight instrument:  the Larmor precession of the neutrons spin in a preparation zone with magnetic field before the sample encodes the individual velocities of the incoming neutrons into precession angles. Provided the sample will not change the neutron velocity (elastic scattering), a symmetric decoding zone compensates for the precession angle accumulated and, leads to the restoration of polarization by spin re-phasing, the so called “spin-echo”.  If the sample changes the neutron velocity (inelastic scattering), the re-phasing will become incomplete and a loss of polarization is measured, which depends on the distribution of differences in the time the neutrons need to fly through the encoding and decoding precession zones. The precise manipulation of neutrons spin allows the use of an intense beam with a broad wavelength distribution at the same time sensitive to neutrons velocity changes of less than 10−4. The SNS-NSE has a modern design based on superconducting technology with high magnetic field homogeneity and takes full advantage of state of the art field correction elements, novel polarizing benders and magnetic shielding for a reliable and precise operation.  

Applications

The SNS-NSE instrument is particularly suitable to investigate slow dynamical processes and unravel molecular motions at nanoscopic and mesoscopic scale. Typical applications include soft-matter dynamics: the molecular rheology of polymer melts; relaxation phenomena in networks and rubbers; interface fluctuations in complex fluids and polyelectrolytes; transport processes in polymeric electrolytes and gel systems, and biophysics studies: the domain dynamics of proteins and enzyme’s; studies of lipid systems and biological membranes; disruptive effects of anti-inflammatory medication on membrane cell organization; transport process thru cell membranes. The SNS-NSE instrument can also aid studies in a variety of fields like condensed matter physics, materials science and magnetism.

Specifications

λmin [Å] λmax [Å] τ min [ps] τ max [ns] Qmin [Å-1] Qmax [Å-1] P2 Qmax [Å-1] P4
2 5 0.1 13 0.08 2.3 3.1
5 8 1 50 0.05 0.9 1.4
8 11 5 130 0.03 0.5 0.9
11 14 12 280 0.03 0.4  
Field Integral Jmax [T m] 0.56  
Scattering Angle 2θmax [deg] 40.0 at P2
    79.5 at P4
Source to Detector L [m] 21.3 at P2
    27.3 at P4
Field Homogeneity H [Å2/ns] 0.7  
Repetition Rate f [Hz] 60