Journal of Neutron Research

Global shortages and cost increases in the Helium industry have initiated a project funded by STFC management to start a Helium recovery project on the ISIS facility. Having an in-house recovery plant will allow significant cost savings to be made by the liquefaction of recovered boil off of helium liquid used in the experimental operations on the facility and the resupply of the liquid. We also envisage resupply of clean Helium back to the facility as high pressure gas. Here we are going to describe our approach to Helium Recovery project at different stages. We start from feasibility study which was followed by the conceptual design review and producing of technical specification of the project. This stage was followed by assembling, testing and commissioning of Helium Recovery system. We also present a few important technical solutions related to hardware and software used in the project

At the Materials and Life Science Experimental Facility in the Japan Proton Accelerator Research Complex, a total of 14 members have participated in the Sample Environment (SE) team since April 2016, including members of the newly joined ³He Neutron Spin Filter Group. The SE equipment commonly used at the beamlines has been prepared by the SE team, while each beamline has prepared some devices that can be adapted to the instrument’s own characteristics and, as such, be useful for the research fields that have been promoted at the beamlines. In addition to existing devices, the SE team has recently introduced new environments, such as a pulsed magnet, a light irradiation system, and a neutron spin filter. In 2015, a new building, the J-PARC Research Building, was inaugurated. This building includes a number of specialized laboratories for sample preparation, sample characterization, SE commissioning, biological and chemical deuteration, development of neutron optical devices and so on.

In this paper a method to control the temperature for a rotating Ultra Small Angle Neutron Scattering (USANS) sample holder is introduced. The temperature is controlled via halogen light bulbs and an infra-red (IR) sensor to avoid interference with the rotation.

A non-magnetic sample stick for top-loading cryostats providing single crystal alignment for neutron scattering is described. This special stick, called Goniostick, allows to tilt crystals by ± 6 ∘ in any direction with ± 0.02 ∘ precision over the 1.5–300 K temperature range. The sample inclination and rotation around the vertical axis are motorised and the sample height is adjustable manually. This Goniostick facilitates neutron scattering experiments and allows the alignment in sample environments which cannot be tilted.

This paper provides an overview of the current development of the ISIS robotic cryogenic sample changer. The system combines a collaborative industrial 6-axis robot with novel adaptions to the traditional vanadium sample can and the closed cycle refrigerator (CCR), producing a simple robust solution for automating sample changes at cryogenic temperatures. Results have shown that the proof of principle has been successful. Future work is focussed on further integration of the robot system with the cryogenic equipment and refining system operation.

Asphyxiation due to the creation of an oxygen depletion atmosphere (ODA) is by far the biggest cause of fatalities when working with cryogenic liquids. Each year, an average of 20 deaths occur in Europe involving people entering an ODA and between 1992 and 2002 in the USA, 85 nitrogen asphyxiation incidents were recorded, in which 80 people were killed. The likely causes of an ODA are confined spaces and poor ventilation, combined with the processing or storage of cryogenic liquids. Prevention can be made by providing well ventilated work areas, supported by the installation of oxygen monitors and alarms. A formal risk assessment document is part of the critical safety provision for personnel working in cryogenic areas. It stipulates how the prevention of an asphyxiation hazard is managed through the introduction of robust control measures and should include oxygen depletion calculations.

In the course of their day, sample environment professionals can be confronted by numerous technical challenges applicable to a range of scientific questions. This paper presents three successful outcomes from user-posed sample environment challenges for in situ neutron scattering experiments undertaken at the Australian Centre for Neutron Scattering (formerly the Bragg Institute). The sample environments presented here have nothing in common other than their novelty. They may not be the best solution but have been constrained by time, resources and ability. The questions the users posed were:

Can we mount a cylinder in cylinder (CIC) rheometer, more regularly used on a small angle scattering instrument, on a diffraction instrument and obtain usable data? Can we supply high-voltage (up to 10 kV) across a sample within the Paris–Edinburgh press while mounted on a powder diffraction instrument? And finally can a Lakeshore 340 and an in-house built liquid conductivity cell do the job of a commercial liquid conductivity meter? This paper presents the engineering and equipment solutions that were used to answer these questions, and in each case the scientific users left with useful, intriguing and, hopefully, publishable data.

The ISIS pulsed neutron and muon source at the Rutherford Appleton Laboratory in Oxfordshire is one of the world-leading centers for research in physical and life sciences. It is owned and operated by the Science and Technology Facilities Council. The popularity of neutron scattering experiments is rapidly growing due to the immense progress achieved in neutron scattering instrumentation and sample environment. Here we are going to review some trends in operation and development of sample environments used in neutron scattering and muon spectroscopy experiments at ISIS. We are also going to discuss ongoing sample environment related research and development projects.

The results of residual stress measurements on autofrettage monoblock pressure vessels before and after 100+ pressure and temperature cycles; and, for the first time, in-situ stress measurements on a vessel under high working pressures as measured by neutron diffraction is presented here. High-pressure vessel design depends heavily on finite element analysis (FEA) which, though useful, requires more data to execute a comparison of the stresses encountered in a working pressure vessel. In-situ pressure stress measurements by neutron diffraction may provide useful data for refinements in FEA calculations and determine vessel pressure/temperature cycling behavior.

The use of strain gauge technology in industry is a common feature for determining mechanical stress in components. However, there is less understanding of the use of this technology in cryogenic applications. The current method of recording gas pressure in containment vessels used at cryogenic temperatures can be considered to be unreliable under certain conditions. A development project has been instigated to investigate the extreme temperature effects on strain gauges working at liquid helium (4 K) temperatures. A small, rectangular helium gas pressure containment vessel has been designed which operates at 20 bar. This will provide deflections to one of its faces onto which a suitable strain gauge can been fixed. The key temperature-dependent variables influencing the strain gauge’s parameters are discussed, with proposed methods to mitigate their effect.

A new sample stick for top-loading cryostats allowing to investigate liquid samples and solid-gas reactions with neutron scattering is described. This stick prevents the freezing of the fluids injected into the cryostat down to the sample cell. The high-pressure capillary of the stick is thermally isolated from the cryogens’ baths and heated to a desired temperature. The maximum pressure that can be applied remotely to the sample is 700 MPa and the sample temperature may be controlled between 1.8 and 550 K. This new stick allows for example to explore ( p , T ) phase diagrams of biological samples that were inaccessible. Extended versions provide 2- or 4-wire in-situ complementary measurements.