Beamline I15 is dedicated to X-ray powder diffraction experiments at extreme pressures and temperatures. Research topics include fundamental Physics and Chemistry, Earth and Planetary Science as well as Materials Science and Engineering.
The beamline provides monochromatic high-energy X-rays from 20 to 80 keV. These X-rays focussed and collimated down to ≤20 µm can penetrate into complex sample assemblies permitting detailed mapping of structural order or disorder, chemical fingerprinting or structure determination.
The new wiggler cryocoolers have been successfully installed. Unfortunately, the Insertion Device group encountered an unexpected problem when testing the wiggler after it had been cooled to 4K. After warming back to room temperature and opening it for examination they found a damaged electrical lead. Repair is underway and this will be followed by testing. A complete assessment of the wiggler’s operational performance will involve pumping down to high vacuum, cooling to 4K, performing a series of tests, and after successful completion warming the device up again to room temperature. A cooling-warming cycle itself takes 2-3 weeks to complete. Therefore, it is impossible to complete the repair and testing in time to insert the wiggler back into the storage ring during the November shutdown. As the wiggler can only be reinserted into the ring during a planned shutdown, the earliest I15 & I15-1 will have X-rays is now 17th January 2023.
Scheduling of user beamtime will commence once the wiggler passes all tests and there is certainty as to when it will be moved back into the ring.
In recent years we have become concerned about the long-term reliability of the coolers fitted to the I15 wiggler cryostat, as the manufactuer no longer makes 4K coolers for the superconducting magnet market and there have been a number of failures leading to the source being unavailable. To address these issues, the wiggler manufacturer, The Budker Institute of Nuclear Physics, agreed to exchange the present coolers for Sumitomo units as these are the current market leader and Budker use them for their latest insertion devices.
Diamond purchased the new coolers directly from Sumitomo and contracted Budker to supply interface components and visit to complete the upgrade. Unfortunately, the pandemic caused the service visit to be delayed a number of times, and just as the visit seemed about to happen the Ukraine war sanctions postponed it indefinitely.
We therefore reluctantly undertook the work internally within the Insertion Devices group with the objective of completing the work ready to re-install in August. However, the work is taking longer than expected, because we have had to modify parts to make them fit and because we do not have complete system drawings. These problems aside, we had aimed to have the re-assembly complete in order that it can be tested and recommissioned during the August shutdown. As the work has taken longer than foreseen, we are now no longer in a position to finish the upgrade and test it before the next run starts in September.
The device will now be installed in October and this regrettably means that I15 and I15-1 will remain off until November. We apologise for this, but we will reschedule your beamtime. Given the long-term issues we have had with this wiggler over the last few years we feel it is better to be certain the device is upgraded, tested and commissioned fully before releasing it to beamline.
Diamond Light Source is the UK's national synchrotron science facility, located at the Harwell Science and Innovation Campus in Oxfordshire.
Copyright © 2022 Diamond Light Source
Diamond Light Source Ltd
Harwell Science & Innovation Campus
Diamond Light Source® and the Diamond logo are registered trademarks of Diamond Light Source Ltd
Registered in England and Wales at Diamond House, Harwell Science and Innovation Campus, Didcot, Oxfordshire, OX11 0DE, United Kingdom. Company number: 4375679. VAT number: 287 461 957. Economic Operators Registration and Identification (EORI) number: GB287461957003.