The BER II neutron source is back in operation and available for experiments following the interruption in availability
The High-Field Magnet (HFM) has attained 26 tesla in an initial test and thereby exceeded expectations. The HFM team is pleased about the well-deserved success.
© HZB/Ingo Kniest
Maintenance work has been successfully concluded – the High-Field Magnet has successfully attained 26 tesla in initial testing. New scientific experiments have become possible.
Berlin, February 2015: following conclusion of more than a of year of repairs and refurbishing, the BER II neutron source will shortly be available to its international user group again. The facility was powered up on Wednesday, February 18 and attained its nominal power level of 9,5 megawatts. Scientists of HZB are meanwhile preparing the measurement equipment so that experimental work can resume following a brief start-up period.
During the service interruption, a weld joint was eliminated that was known to be a potential weak point. This involved a weld joint for a seal located in the area of the separator between the two reactor pool halves. Damage to this weld joint was discovered in 2010 and has been carefully monitored since that time. This did not involve a component critical to safety; nevertheless, it was decided in 2013 to completely remove the weld joint.
At the same time, the new High-Field Magnet went through final assembly and was setup in its final operating position inside in the Neutron Guide Hall. Its 26-tesla magnetic field was first generated in December 2014 and it maintained this value stably over a longer period of time. So it even exceeded its target value of 25 tesla.
Following the maintenance period, an important objective was reached with the successful resumption in BER II operations: participants of the international Neutron School can again be offered actual neutron experiments of the customary high quality. The 12-day advanced course for young scientists will be taking place in Berlin for the 35th time, from February 26th to March 6th.
Developing and successfully setting up the High-Field Magnet, unique for neutron experiments, has only taken 7.5 years. All of the comparable hybrid magnet construction projects worldwide during the past 25 years have taken between 9.5 and 16 years. The brief project length can therefore be viewed as top of its class. In addition, the project remained within its planned budget of just under 21 mil. EUR after adjusting for inflation.
The High-Field Magnet represents yet another first-class instrument that is being connected to the neutron source for the final BER II support period. Completely new kinds of experiments become possible that will open up access to new science, such as researching superconduction and magnetic phase transitions in solid-state materials, for example.
- MXene as a frame for 2D water films shows new propertiesAn international team led by Dr. Tristan Petit and Prof. Yury Gogotsi has investigated MXene with confined water and ions at BESSY II. In the MXene samples, a transition between localised ice clusters to quasi-two-dimensional water films was identified by increasing temperature. The team also discovered that the intercalated water structure drives a reversible transition from metallic to semiconducting behaviour of the MXene film. This could enable the development of novel devices or sensors based on MXenes.
- Self assembling monolayer can improve lead-free perovskite solar cells tooTin perovskite solar cells are not only non-toxic, but also potentially more stable than lead-containing perovskite solar cells. However, they are also significantly less efficient. Now, an international team has succeeded in reducing losses in the lower contact layer of tin perovskite solar cells: The scienstists identified chemical compounds that self-assemble into a molecular layer that fits very well with the lattice structure of tin perovskites. On this monolayer, tin perovskite with excellent optoelectronic quality can be grown, which increases the performance of the solar cell.
- Scrolls from Buddhist shrine virtually unrolled at BESSY IIThe Mongolian collection of the Ethnological Museum of the National Museums in Berlin contains a unique Gungervaa shrine. Among the objects found inside were three tiny scrolls, wrapped in silk. Using 3D X-ray tomography, a team at HZB was able to create a digital copy of one of the scrolls. With a mathematical method the scroll could be virtually unrolled to reveal the scripture on the strip. This method is also used in battery research.