The neutron single-crystal instrument KOALA was part of the initial suite of instruments proposed to take beam from the OPAL reactor at ANSTO. The crystallographic community contributed generously to the workshops around instrument choices and the initial recommendation was that both a LAUE and a monochromatic instrument should be built. We are fortunate that the choice was ultimately made to purchase an instrument built to the same specifications as the instrument VIVALDI at the ILL in Grenoble.
The advantages of a LAUE instrument are considerable - most notably in using the full beam available we are not throwing away most of the neutrons available through monochromation. The choice of an instrument which accumulates the image over a chosen exposure length and is then read out suffers from some issues of overlap and potential ambiguity, but is far less demanding technologically than an instrument where detectors capable of time stamping detection events are required. Such detection systems are of immense expense and sophistication even with only a limited coverage of reciprocal space and there are challenges in the data reductions even when the time information which allows calculation of the wavelength is available.
Ross Piltz' LAUEG software facilitated Users of the instrument to be able to undertake their own data reduction in many instances and Ross' expert guidance resolves most issues where non-routine or challenging problems arise.
The use of a COBRA cryostream was a major enhancement to our offering as it facilitated studies of air and moisture sensitive samples under conditions of controlled temperatures comparable to lab X-ray studies and some of our greatest successes have used this device.
By 2019, we faced a major serviceability issue with the instrument with motion controllers not compatible with the otherwise standard units employed at ANSTO reaching the end of their life and difficulties with many components becoming obsolete. The major components failing were in the instrument electronic controls and an initial plan to build a new control unit was created and costed. Subsequently, a complete new build instrument was also costed. The community was again fortunate that the decision to construct a copletely new instrument was made as this allowed us to build the new instrument away from the instrument position and to run the original instrument as long as possible, only decommissioning it once we were ready to hot commission the new instrument. In addition, a wide-bore cryostream was commissioned from Oxford Cryosystems to reduce ice-formation on the larger crystals required for neutron diffraction studies.
Our new instrument was designed and assembled by a team of instrument specialists with some elements constructed to our specifications. The new instrument together with the wide-bore cryostream has resolved a majority of the issues and awkwardness which were inherent in the original instrument and publication have flowed promptly from the new instrument. We are looking forward to operations resuming after the long shutdown which was delayed until 2024.
A range of case studies and success stories will be presented.