Triple-axis spectrometry (TAS, three axis spectroscopy) is a technique used in conjunction with

inelastic neutron scattering Neutron scattering, the irregular dispersal of free neutrons by matter, can refer to either the naturally occurring physical process itself or to the man-made experimental techniques that use the natural process for investigating materials. Th ...

. The instrument is referred to as triple-axis spectrometer (also called TAS). It allows measurement of the

scattering In physics, scattering is a wide range of physical processes where moving particles or radiation of some form, such as light or sound, are forced to deviate from a straight trajectory by localized non-uniformities (including particles and radiat ...

function at any point in

energy Energy () is the physical quantity, quantitative physical property, property that is transferred to a physical body, body or to a physical system, recognizable in the performance of Work (thermodynamics), work and in the form of heat and l ...

and

momentum In Newtonian mechanics, momentum (: momenta or momentums; more specifically linear momentum or translational momentum) is the product of the mass and velocity of an object. It is a vector quantity, possessing a magnitude and a direction. ...

space physically accessible by the spectrometer.

History

The triple-axis spectrometry method was first developed by

Bertram Brockhouse Bertram Neville Brockhouse, (July 15, 1918 – October 13, 2003) was a Canadian physicist. He was awarded the Nobel Prize in Physics (1994, shared with Clifford Shull) "for pioneering contributions to the development of neutron scattering te ...

at the National Research Experimental NRX reactor at the

Chalk River Laboratories Chalk River Laboratories (; also known as CRL, Chalk River Labs and formerly Chalk River Nuclear Laboratories, CRNL) is a Canadian nuclear research facility in Deep River, about north-west of Ottawa. CRL is a site of significant research and ...

in Canada. The first results from the prototype triple-axis spectrometer were published in January 1955 and the first true triple-axis spectrometer was built in 1956. Bertram Brockhouse shared the 1994

Nobel Prize The Nobel Prizes ( ; ; ) are awards administered by the Nobel Foundation and granted in accordance with the principle of "for the greatest benefit to humankind". The prizes were first awarded in 1901, marking the fifth anniversary of Alfred N ...

for Physics for this development, which allowed elementary excitations, such as

phonon A phonon is a collective excitation in a periodic, elastic arrangement of atoms or molecules in condensed matter, specifically in solids and some liquids. In the context of optically trapped objects, the quantized vibration mode can be defined a ...

s and

magnon A magnon is a quasiparticle, a collective excitation of the spin structure of an electron in a crystal lattice. In the equivalent wave picture of quantum mechanics, a magnon can be viewed as a quantized spin wave. Magnons carry a fixed amou ...

s, to be observed directly. The Nobel citation was "for pioneering contributions to the development of neutron scattering techniques for studies of condensed matter" and "for the development of neutron spectroscopy".

TAS instruments in current use

FRM-II Forschungsneutronenquelle Heinz Maier-Leibnitz

*PANDA – a

cold neutron The neutron detection temperature, also called the neutron energy, indicates a free neutron's kinetic energy, usually given in electron volts. The term ''temperature'' is used, since hot, thermal and cold neutrons are moderated in a medium with ...

triple-axis spectrometer. *PUMA – a thermal neutron triple-axis spectrometer with multianalyser-detector option. *TRISP – a thermal neutron triple-axis spin echo spectrometer. *KOMPASS – a cold triple-axis spectrometer with polarization analysis *MIRA – a cold triple-axis spectrometer

Helmholtz-Zentrum Berlin für Materialien und Energie

*FLEX – a cold neutron triple-axis spectrometer with optional neutron resonance spin echo mode. *E1 – a thermal neutron triple-axis spectrometer with polarization analysis.

Paul Scherrer Institut

*RITA-II – a cold-neutron triple-axis spectrometer. *TASP – a cold-neutron triple-axis spectrometer with polarization analysis and neutron spherical polarimetry. *EIGER – a thermal-neutron triple-axis spectrometer.

Institut Laue-Langevin

*IN1 – a hot-neutron triple-axis spectrometer. *IN3 – a thermal-neutron triple-axis spectrometer for tests. *IN8 – a high-flux thermal-neutron triple-axis spectrometer. *IN12 – a cold neutron triple-axis spectrometer. *IN14 – a cold-neutron triple-axis spectrometer with polarized neutron capability. *IN20 – a thermal-neutron triple-axis spectrometer with polarized neutron capability. *IN22 – a thermal-neutron triple-axis spectrometer with polarized neutron capability. *D10 – a thermal-neutron four-circle

diffractometer A diffractometer is a measuring instrument for analyzing the structure of a material from the scattering pattern produced when a beam of radiation or particles (such as X-rays or neutrons) interacts with it. Principle A typical diffractometer c ...

with a triple-axis energy analysis option.

CEA/Saclay Laboratoire Léon Brillouin

*1T-1 – a double-focusing thermal neutron triple-axis spectrometer. *2T-1 – a thermal-neutron triple-axis spectrometer. *4F-1 – a cold-neutron triple-axis spectrometer. *4F-2 – a cold-neutron triple-axis spectrometer.

NIST Center for Neutron Research

*SPINS – a cold-neutron triple-axis spectrometer with polarized neutron capability. *BT-7 – a thermal-neutron triple-axis spectrometer with polarized neutron capability. *MACS – a high-flux cold-neutron multi-axis spectrometer.

ORNL HFIR

*CTAX – a cold-neutron triple-axis spectrometer. *PTAX(HB1) – a thermal-neutron triple-axis spectrometer specifically designed for polarized neutron measurements. *FIETAX (HB1A) – a fixed incident energy thermal-neutron triple-axis spectrometer. *TAX (HB3) – a high-flux thermal-neutron triple-axis spectrometer.

ANSTO Bragg Institute

*TAIPAN – a thermal-neutron triple-axis spectrometer with polarized neutron capability and beryllium-filter option. *SIKA – a cold-neutron triple-axis spectrometer with polarized neutron capability.

MURR University of Missouri Research Reactor

*Triax – a thermal-neutron triple-axis spectrometer.

References

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External links

Nobelprize.org page for the 1994 Nobel Prize for Physics
Neutron-related techniques