BESSY II is ready for user service
A view of what had been the practically empty segment at EMIL in the experimental hall; the beam tubes for EMIL are already being marked out on the brand-new flooring. Photo: Ingo Müller/HZB
BESSY II was shut down as scheduled from February 9th until the end of March for refurbishment and modernization. The accelerator is operational once again, and has been running since the beginning of April, beginning with beam scrubbing to increase the lifetime of the electrons in the storage ring and to improve operation. At the same time teams have been working on the calibration and commissioning of their instruments. BESSY II will be ready for user service once again on April 21 2015.
The new flooring shines - it desperately needed to be re-done in heavily worn areas. But that is just the most obvious update undertaken during this shutdown. At least five major projects were coordinated since the beginning of February. „Our best thanks to the staff, who worked overtime to get everything ready“, says Prof. Anke Kaysser-Pyzalla, scientific director of HZB, „now User Service can start again as planned.“
As a result BESSY II is now equipped with a state-of-art Personal Safety Interlock to ensure safe operation. “The interlock shuts off the machine immediately or brings it to a safe state if someone makes an error while in operation or opens a door to a restricted area”, explains Müller. The new interlock system is based on modern safety PLCs. These programmable logic controllers are certified and the operation of the entire system was inspected and accepted by the radiation safety officer.
Vacuum Sement rebuilt for EMIL
The EMIL laboratory has been added, therefore a vacuum segment in the storage ring needed to be completely re-built. "During this shutdown we also prepared the vacuum system needed for both undulators that have been designed by the Undulator-team specifically for EMIL", Christian Jung (Scientific-Technical Infrastructure II) explains. This is because energies of up to 10,000 eV will be needed for EMIL instead of just the normal 60 to 2000 eV for nominal BESSY II operations.
Modern RF amplifyers and a multipole wavelength shifter have been installed
The replacement of two out of the four klystron-based RF amplifiers, used to power the RF cavities was also very elaborate. They were replaced by newly designed Solid State RF amplifiers. The multipole wavelength shifter on the EDDI beamline, which was damaged last year, has now also been repaired and re-installed.
Dipole front-end systems will get new absorbers
“In addition, we installed new beam line absorbers on a quarter of the dipole front-end systems during this shutdown. That was necessary because we have a 300 mA beam current present at all times in the ring due to operating in top-up mode", Jung explains.
User service resumes April 21, but the next shutdown is already being planned. The work that began during the 2013 shutdown should be completed by the end of 2015. Still on the agenda: replacement of the last two “old” RF cavities in the machine with new RF cavities, installation of the two new undulators for EMIL, changeover of the remaining klystron-based RF amplifiers to Solid State technology as well as fitting new absorbers in the remaining dipole front-end systems.
- Green hydrogen: MXenes shows talent as catalyst for oxygen evolutionThe MXene class of materials has many talents. An international team led by HZB chemist Michelle Browne has now demonstrated that MXenes, properly functionalised, are excellent catalysts for the oxygen evolution reaction in electrolytic water splitting. They are more stable and efficient than the best metal oxide catalysts currently available. The team is now extensively characterising these MXene catalysts for water splitting at the Berlin X-ray source BESSY II and Soleil Synchrotron in France.
- Review on ocular particle therapy (OPT) by international expertsA team of leading experts in medical physics, physics and radiotherapy, including HZB physicist Prof. Andrea Denker and Charité medical physicist Dr Jens Heufelder, has published a review article on ocular particle therapy. The article appeared in the Red Journal, one of the most prestigious journals in the field. It outlines the special features of this form of eye therapy, explains the state of the art and current research priorities, provides recommendations for the delivery of radiotherapy and gives an outlook on future developments.
- "BESSY is of immense importance for Berlin"At the end of August, the Senator for Research, Health, and Long-Term Care, Dr Ina Czyborra, together with the State Secretary for Science, Dr Henry Marx, ended her summer tour with a visit to HZB in Adlershof. She publicly declared her political support for the new construction of BESSY III.