Cold Neutron Triple-Axis Spectrometer


Mission Statement

The US/Japan Cold Neutron Triple-Axis (CTAX) Spectrometer is a collaboration of the Neutron Sciences Directorate at Oak Ridge National Laboratory and the Institute of Solid State Physics at the University of Tokyo, as part of the US-Japan Cooperative Program on Neutron Scattering. It is a cold neutron spectrometer to study static and dynamic properties of spin and lattice in materials.

Instrument Description

Of the four triple-axis spectrometers installed at HFIR, CTAX is a conventional cold neutron triple-axis spectrometer with variable incident energy and sample-analyzer distances. The cold guide 4 bender and guide hall shielding reduce background levels at CTAX, and the 15-cm-tall guide profile is well exploited by CTAX′s vertically focusing PG(002) monochromator. To enhance accommodation of strong magnetic fields at the sample position and simplify future polarization analysis, the amount of ferromagnetic material has been minimized in the construction of this instrument.



CTAX is suited for studies of nuclear and magnetic structures, quasi-elastic scattering, and lattice and magnetic dynamics in a variety of materials, including superconductors, transition metal oxides, multiferroics, thermoelectric materials, and low-dimensional quantum magnets. It enables better analysis of low-energy excitations in materials with high signal-to-noise ratio. CTAX can accommodate a wide variety of sample environments, including high temperature furnaces (< 1770 K), ultra-low temperature cryostats (> 0.05K), vertical-field cryomagnets (< 8T), horizontal-field cryomagnet (< 6 T) and pressure cells (< 2 GPa). The materials best suited for study on CTAX facilitate data transmission in computers; impact the capacity of computer memory (hard disk); and improve the efficiency of electric devices.


Incident energy range 2 - 18 meV
Final energy range ≥3.0meV
Sample scattering angles -15° ≤ 2Θs ≤ 115°, with additional restrictions depending on Ei
Collimation before mono-chromator Guide dependent (40′ at 2 meV, 20′ at 18 meV)
Collimation after mono-chromator 10′, 20′, 40′, 80′