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With the closure of the BER-II Reactor in Berlin, the Helmholtz Zentrum Berlin (HZB) started to find new homes for their suite of world-class neutron scattering instruments. In September 2015, it w...

QUOKKA is a 40 m pinhole small-angle neutron scattering instrument in routine user operation at the OPAL research reactor at the Australian Nuclear Science and Technology Organisation. Operating with a neutron velocity selector enabling variable wavelength, QUOKKA has an adjustable collimation system providing source–sample distances of up to 20 m. Following the large-area sample position, a two-dimensional 1 m2 position-sensitive detector measures neutrons scattered from the sample over a secondary flight path of up to 20 m. Also offering incident beam polarization and analysis capability as well as lens focusing optics, QUOKKA has been designed as a general purpose SANS instrument to conduct research across a broad range of scientific disciplines, from structural biology to magnetism. As it has recently generated its first 100 publications through serving the needs of the domestic and international user communities, it is timely to detail a description of its as-built design, performance and operation as well as its scientific highlights. Scientific examples presented here reflect the Australian context, as do the industrial applications, many combined with innovative and unique sample environments.

A combined solution is presented for minimizing the safety hazards associated with closed cycle cryostats described by Swainson & Cranswick [J. Appl. Cryst.(2010),43, 206–210]. The initial solution is to install a vent tube with one open end deep inside the sample space and a pressure relief valve at the top. This solution works for either a cryogen or a cryogen-free (closed cycle) system. The second approach, which can be combined with the first and is applicable to cryogen-free cryostats, involves electrically interlocking the closed cycle refrigerator compressor to the sample space, so that the system cannot be cooled in the presence of a leak path to air.

A large-volume single-pass flow-through cell forin situneutron diffraction investigation of hydrothermal crystallization processes is reported. The cell is much more versatile than previous designs owing to the ability to control independently and precisely temperature (up to 673 K), pressure (up to 46 MPa), flow rate (0.01–10 ml min−1) and reaction-fluid volume (≥65 ml). Such versatility is realized by an innovative design consisting of a room-temperature and ambient-pressure external fluid supply module, a high-pressure reaction module which includes a high-temperature sample compartment enclosed in a vacuum furnace, and a room-temperature and high-pressure backpressure regulation module for pressure control. The cell provides a new avenue for studying various parameters of hydrothermal crystallizations independently,in situand in real time at extreme hydrothermal conditions (e.g.supercritical). The cell was successfully commissioned on the high-intensity powder diffractometer beamline, Wombat, at the Australian Nuclear Science and Technology Organisation by investigating the effect of pressure on the hydrothermal pseudomorphic conversion from SrSO4(celestine) to SrCO3(strontianite) at a constant temperature of 473 K and flow rate of 5 ml min−1. The results show that the increase of pressure exerts a nonlinear effect on the conversion rate, which first increases with increasing pressure from 14 to 20 MPa, and then decreases when pressure further increases to 24 MPa.

For almost 30 years, at synchrotron facilities, it has been possible to perform small-angle x-ray scattering experiments whilst simultaneously measuring differential scanning calorimetry (DSC). However, a range of challenges exist to enable the collection of simultaneous small-angle neutron scattering (SANS) and DSC data associated not only with intrinsic flux limitations but also scattering geometry and thermal control. The development of a DSC (temperature range ca. −150 °C to 500 °C) suitable for SANS is detailed here and its successful use is illustrated with combined measurements on a binary blend of normal alkanes in which one component has been deuterium labelled.