Polarized neutrons Industrial Placement

at  Science and Technology Facilities Council STFC

SCIENCE AND TECHNOLOGY FACILITIES COUNCIL

Salary: £23,328 per annum
Hours: Full time
Contract Type: Fixed Term (12 months)
Location: Science and Technology Facilities Council, Rutherford Appleton Laboratory Harwell, Oxfordshire
Closing date: 20th October 2024
Interview date: December 2024/January 2025 (travel and accommodation will be reimbursed)
Start date: September 2025

PLEASE NOTE THAT WE CAN ONLY ACCEPT A MAXIMUM OF 2 APPLICATIONS PER CANDIDATE.

The ISIS Neutron & Muon Instrument Development group (NMIDG) was formed in 2019 to develop new instrumentation and simulation methods and to provide staff training and advice. Within NMIDG, the Polarized Neutrons section, that is currently consists of two scientists and one technician, is responsible for the development of new polarized instrumentation and software, as well as the provision of polarized infrastructure for several instruments.
A neutron beam is called polarized when the spins of the neutrons are dominantly aligned in the same direction. Such beams can be used to improve the information gained from scattering experiments, by, for example, enabling the separation of the different scattering processes that contribute to the overall signal (see e.g. https://www.isis.stfc.ac.uk/Pages/SH20_PLET.aspx). Typically, application of neutron polarization analysis on an instrument requires the installation of several additional components, including a polarizer to prepare the polarized incident beam and an analyzer to distinguish the change in beam polarization after scattering from the sample. A commonly used technology for both is hyperpolarized 3He spin-filter. It constitutes a vessel that contains 3He gas with a high atomic polarization, where, as for polarized neutron beams, the atomic spins in the gas are preferentially aligned. 3He spin filters exploit the fact that a 3He atom in a particular spin state absorbs neutrons with the opposite spin state, and thus, that a volume of polarized 3He gas will transmit only one spin state of the neutron beam.
3He polarization decays with time. One of the key contributions to it is related to the walls of the spin-filter vessel (typically made of glass). While the exact physical mechanisms are poorly understood, surface adsorption, magnetic defects, and surface chemistry are all thought to play important roles. Recently we have launched a project to prepare spin filter cells from materials that are cleaner and more reproducible than glass, like single crystal silicon. In particular, it includes the first systematic study of characteristics and treatment of the cell walls in relation to the spin filter performance. Currently we are looking for an independent and motivated placement student to carry out research and development work towards the goal of further improving 3He cell performance.

• The previous placement student has developed a chamber for in-situ X-ray and neutron reflectometry study of silicon wafers coated by alkali metal. The next stage of the project will include a detailed reflectometry study of various protocols for the alkali metal coating on the silicon substrate and their influence on the decay of the 3He polarization.
• If successful, the obtained knowledge will be used to improve both existing and future 3He cells to be deployed on the Larmor and LET instruments at ISIS.
• In addition to the above, you will also have the opportunity to take part in other Polarized Neutrons section activities, including experimental support on neutron instruments. Full scientific and technical support will be provided during the placement.
• You will be also able to present the results of your work in the scientific meeting and/or seminars, for example at the UK Neutron & Muon Science and User Meeting (NMSUM). The work of our previous placement student presented at NMSUM-2024 won a student poster prize.
• Given the variety of activities the Polarized Neutrons section is involved in, the working environment is dynamic and sometimes fast paced. This makes for a team culture where creativity, independence, and a sense of adventure are valued. At the same time, you will be working in a small, friendly, and tight-knit group where you will be valued as a full member of the team.