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Upcoming Seminars

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Machine Learning-based Beam Size Stabilization at ALS

Date: August 7, 2020 1:00pm (remote)

Speaker: Simon Leeman (LBNL)

 In state-of-the-art synchrotron light sources the overall source stability is limited by the achievable level of electron beam size stability. This source size stability is presently on the few- percent level, which is still 1-2 orders of magnitude larger than already demonstrated stability of source position/angle (slow/fast orbit feedbacks) and current (top-off injection). Until now, source size stabilization has been achieved through corrections based on a combination of static predetermined physics models and lengthy calibration measurements (feed-forward tables), periodically repeated to counteract drift in the accelerator and instrumentation. We now demonstrate for the first time [PRL 123 194801 (2019)], how application of machine learning allows for a physics- and model-independent stabilization of source size relying only on previously existing instrumentation in ALS. Such feed-forward correction based on neural networks that can be continuously online-retrained achieves source size stability as low as 0.2 microns rms (0.4%) which results in overall source stability approaching the sub-percent noise floor of the most sensitive experiments. 
 
 




High-dimensional geometry and the landscapes of deep neural networks

Date: July 31, 2020 1:00pm (remote)

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