POWTEX visits POWGEN.

Area of Science:

• Materials Science and Engineering
• Condensed Matter Physics
• Neutron Scattering Techniques

Background:

• The 3He crisis necessitated the development of alternative neutron detectors for large-area diffractometers.
• The POWTEX neutron diffractometer is under construction for powder and texture analysis at the FRM II research reactor.
• Existing neutron detection technologies face limitations, driving innovation in detector design and data analysis.

Purpose of the Study:

• To report on the performance of a novel 3He-free detector unit developed for the POWTEX diffractometer.
• To evaluate the detector's data quality and refine analysis methods using multi-dimensional refinement.
• To compare novel 2D refinement techniques with conventional 1D methods for time-of-flight neutron powder diffraction data.

Main Methods:

• Operation of a POWTEX detector unit on the POWGEN neutron powder diffractometer at the Spallation Neutron Source.
• Characterization of transport damage and recalibration of detector voxel positions.
• Data reduction using PowderReduceP2D in Mantid and multi-dimensional refinement with a modified GSAS-II suite.

Main Results:

• The POWTEX detector unit successfully acquired angular- and wavelength-dependent data, despite sustaining transport damage.
• Instrumental resolution parameters were determined using a powdered diamond standard sample.
• Multi-dimensional (2D) refinement of BaZn(NCN)2 revealed subtle but significant differences in precision compared to conventional 1D refinement, particularly in lattice parameters and bond angles.

Conclusions:

• The developed 3He-free detector technology is viable for large-area neutron diffractometers.
• Multi-dimensional data refinement offers enhanced precision for structural analysis from time-of-flight neutron diffraction data.
• These findings are crucial for the successful operation of POWTEX and other future neutron scattering facilities.