The ALBA Synchrotron is a complex of electron accelerators aimed at providing synchrotron light. It consists of three accelerators: a LINAC – where the electrons received the first acceleration-, a booster – where they are accelerated up to the nominal energy of 3 GeV-, and a storage ring – where the electrons are kept at a constant energy and their synchrotron radiation emmission is used for feeding the operating beamlines-.
At the storage ring of ALBA, the accelerating voltage of the RF frequency compensates for the energy loss of the electrons due to the emission of synchrotron radiation. It also groups the electrons in bunches separated by 60 cm, which is the wave length of the RF frequency (500 MHz), corresponding to a distance in time of 2 nanoseconds. The ALBA circumference is 268.8 m, so that there are 448 "spaces" that can be filled with electrons.
Up to now, bunches were refilled uniformily, with no special control on the single bunch current. Now a group of physicists and engineers form the ALBA Synchrotron has designed and tested an algorithm that allows controlling independently the quantity of electrons injected in any of the 448 bunches and makes sure that the initial distribution is kept during the run.
This development will be a valuable tool to perform time-resolved experiments for studying dynamic processes taking place in the nanoseconds time scale. The possibility of performing time-resolved experiments together with the high brilliance of the synchrotron light are a must on any advanced synchrotron light facility, and is now successfully implemented at ALBA.
With the launching of the algorithm to control the injection, the ALBA accelerators continue improving the quality of the light provided for the experiments.
The figures above shows (left) the initial filling pattern and (right) the pattern after 4 hours. One can notice how the initial ripple on the pattern decreases with time, indicating that the algorithm that decides which bucket needs refilling at each injection in top-up is working properly.
The same application has been used to write the name ALBA with electrons. This image won the contest for the ALBA Open Day T-Shirt in 2016.
