Mission Statement

Measures excitations in small single-crystals with optional polarization analysis.

Instrument Description

HYSPEC is a versatile spectrometer that allows for ground-breaking investigations of the low-energy, atomic-scale dynamical properties of crystalline solids. Its Bragg focusing optics makes it well suited for measurement of excitations in small single-crystal specimens in a wide range of ancillary sample environments. Full or partial neutron polarization analysis can be deployed to provide unambiguous separation of nuclear and magnetic scattering.

HYSPEC is a high-intensity, time-of-flight, direct-geometry spectrometer (DGS). The incident neutron beam is monochromated using a Fermi chopper with short, straight blades, and is then vertically focused by Bragg scattering onto the sample position by either a highly-oriented pyrolitic graphite (unpolarized) or a Heusler (polarized) crystal array. Neutrons are detected by a bank of 3He tubes that can be positioned over a wide range of scattering angles about the sample vertical axis. Polarization analysis is accomplished by using the Heusler crystal array to polarize the incident beam, and a supermirror wide-angle polarization analyzer, designed and fabricated by the Paul Sherrer Institut, to analyze the scattered beam.

HYSPEC’s niche among the family of DGS’s at the SNS and the triple axis spectrometers at HFIR includes:

  • Polarization analysis option 
  • Large configurable horizontal angle detector acceptance
  • Vertical focusing enables good statistics, for either small single crystals or extreme conditions
  • A cold neutron incident energy range optimized for 3.8 meV < Ei < 60 meV unpolarized and  3.8 meV < Ei < 25 meV polarized
  • Moderate energy transfer resolution, between that of CNCS andcold neutron triple-axis spectrometers such as CTAX at HFIR

Applications

HYSPEC can be used for leading-edge studies in disciplines such as quantum materials.  Contemporary popular themes comprise unconventional superconductors, ininerant magnets, and geometrically frustrated magnets.

Specifications

ModeratorCoupled cryogenic hydrogen
Source – Fermi chopper distance37.2 m
Chopper – smaple distance3.2 m
Sample – detector distance4.5 m
Focusing crystals to sample distance1.4 — 1.8m
Incident energy range3.8 — 60 meV
Resolution (elastic scattering)2 — 20% Ei
Detector coverage horizontal2° — 135°
Detector coverage vertical-7° — 7°
Minimum detector angle
Beam Size6 cm x 4 cm unfocused, or 3 cm x 3 cm focused, with fully adjustable motorized slits in the horizontal and vertical directions