Positive Spin, August 2026
12 Aug 2026
Welcome to the August edition of Positive Spin.
Dear Friends and Colleagues,
In this issue we provide updates on current projects and investment within the muon group and showcase significant progress with regard Super-MuSR and the RIKEN Solenoid and MuX upgrades. Super-MuSR is forecast to be available for Users in 2028, with the RIKEN Solenoid being replaced in the 2027 long shutdown. All three initiatives will greatly enhance muon capability and instrumentation. In addition, we currently have 4 joint PhD studentships as well as industrial placement students. The science output from the facility remains strong, but please do tells us about publications and/or theses containing ISIS muon data.
You may have seen announcements made by STFC, UKRI, as well as reports in the media, regarding ISIS. These notices include reduced ISIS running and possible closure of the muon facility. However, I would like to draw your attention to the letter to the User community from the ISIS Director, in which we state that we are exploring all possibilities to ‘maintain as much capability and capacity as we can’. Your support during these challenging times is greatly appreciated.
Best wishes,
Aidy
Introducing
Megan Hanes and Chendur Chandrasekaran
We are pleased to introduce the most recent members of the Muon Group - Megan Hanes and Chendur Chandrasekaran
Megan is an undergraduate physics student at the University of York, working in the muon group as a placement student. Her project is simulating a potential low energy muon beamline at ISIS which would allow low energy μSR experiments to be done to study surface and thin film science within magnetism, semiconductors and superconductors. In her project she has explored using frictional cooling to achieve a competitive efficiency of low energy muons. Next year she plans to finish her masters and spend time with the ducks on campus.
Chendur is an undergraduate physics student from the University of Manchester, currently working as an industrial placement student in the muon group. His role primarily involves improving EVA, the data analysis software package used in the MuX instrument. He has also developed a G4beamline interface to model negative muon implantation in bulk samples, and plans on specialising in the field of computational physics during his masters next year.
News
ISIS-PSI Muon Spectroscopy Meeting, July 21 2026, Switzerland
On Tuesday 21 July 2026, muon group members from the Paul Scherrer Institute (PSI), Switzerland, and the ISIS Pulsed Neutron and Muon Source, UK, met at PSI for the first of a new series of annual collaboration meetings. This in-person opportunity allowed the two teams to discuss, and identify, ways in which they, and the other international muon sources, might work more effectively together. Discussion topics included the development of detector technologies and standardisation of analysis packages to, future capability, funding opportunities and enhanced community engagement.
The next discussion meeting is planned at ISIS to coincide with the 40-Years-ISIS-Muons symposium (Mar 22 - Mar 25, 2027). More details about this milestone celebration to follow soon.
Publications
Please inform your local contact and the ISIS User Office of publications arising from work on Muon instruments. A link to the work can then be included on the STFC publications database: http://epubs.stfc.ac.uk
Instrumentation
MuX developments
The MuX instrument, located in Port 4 in the RIKEN-RAL facility, will undergo a major upgrade (during the 2027 long shutdown period). Some of the important upgrades include (i) a 3D frame to support 8 ORTEC high-purity germanium (HPGe) detectors, (ii) a dedicated xyz-movable sample holder, (iii) semi-automatic liquid nitrogen filling system for the HPGe detectors, (iv) new data acquisition system (DAQ), a 280-channel R5560SEB digitiser from CAEN, integrated with the IBEX experimental control software. These upgrades will not only increase the accuracy and precision of the measurements but also reduce the measurement times considerably.
Putting a "positive spin" on the solenoid project
The RIKEN beamlines use a 5 Tesla, 5.5 metre long solenoid to collect positive or negative pions and allow them to decay into high momentum muons. The existing superconducting solenoid is over 30 years old and its energy-hungry cooling system is becoming increasingly unreliable. A replacement solenoid with modern technology such as efficient cryocoolers is now being manufactured. The outer vacuum vessel has been constructed and coil winding is about to start. It is scheduled to be delivered ready for installation in the 2027 long shutdown. The power supply will be integrated into IBEX so that the muon momentum and therefore penetration depth can be scripted. The image is a CAD drawing of the new solenoid.
Illuminating EMu
At EMU, we have recently commissioned an illumination setup using light-emitting diodes (LEDs), developed in collaboration with a team from Sweden. A newly developed re-entrant tube with an optical window positions the LED module close to the sample, enabling illumination with a high-flux light beam. The sample is mounted on a CCR at an angle that allows simultaneous muon irradiation and illumination (see photo). LED wavelengths can be selected from a wide range of Thorlabs products, and users can swap the LED in situ to change wavelength without breaking vacuum. The setup has already been successfully used in an experiment and is now ready for use by the user community.
Super MuSR
Both Spin Rotators have been fully assembled in the clean tent. The survey group has aligned the electrodes in Spin Rotator 1 to achieve extremely high accuracy. This is a fantastic achievement, highlighting the benefits from the collaboration with the Paul Scherrer Institute for this project. They are due to align the electrodes in Spin Rotator 2 in the next couple of weeks. Spin Rotator 1 has been moved into the high voltage (HV) test area, with testing starting soon to reach +/- 215 kV.
The HV test vessel itself has been run up to 215 kV with both resistor boxes, proving critical aspects of the Spin Rotator design such as the ceramic insulator assembly, electromagnetic design, surface finishes and cleanliness.
Work is progressing on the detector build. The 960 scintillator tiles are all being made by hand, in five different sizes. The fibre optics are first glued into place, then lapped down to size before being polished. Each is then inspected and wrapped ready for testing before installation in 2027.
The instrument pre-build is also progressing.
Digital Muons
We are also developing the event-by-event data collection that will be deployed on Super-MuSR and transferred to the other muon instruments later. This will allow continuous measurements as experiment parameters like temperature or magnetic field are varied smoothly, making even better use of the time the sample is in front of the beam. Test measurements to demonstrate the full pipeline of data collection, reduction, and analysis are already underway. Results from a temperature scan on the antiferromagnet La2CuO4 are shown, where the precession of muon spins in the internal magnet fields reduces in frequency as the temperature increases towards the ordering temperature.
A.ny O.ther B.usiness
SAMPLE DISPOSAL (after experiments) We would like to remind users that we’re only able to store samples for a limited time following experiments and going forward we’ll be disposing of unclaimed samples after two years from the date of your experiment (or Xpress measurement). Sample return is easily arranged through your local contact.
CO–AUTHORS Please remember to include Muon Group staff as co–authors on publications when deemed appropriate
CYCLE DATES Forthcoming cycle date can be found HERE
COMMENTS/SUGGESTIONS Please send comments and suggestions about Positive Spin to Mark Telling
