User:StefanUlmerBASE

Stefan Ulmer is a chief scientist at RIKEN, Wako, Japan and Spokesperson of CERN’s BASE collaboration. He has received his PhD degree (2011) for the “first observation of spin flips with a single trapped proton”, which was a milestone experiment in proton/antiproton magnetic moment measurements, and led to the first high-precision measurement of the magnetic moment of a single trapped proton with a fractional precision of 3 parts in a trillion. In 2011 he joined the ASACUSA antihydrogen effort as a post-doc where he contributed to the production of the first beam of antihydrogen atoms. In 2012 he was appointed as PI of a RIKEN-junior research group, within this program he founded CERN’s BASE collaboration with the goal to compare the fundamental properties of protons and antiprotons with ultra-high precision. In 2013 BASE was approved by CERN’s research board. In the first run of the BASE experiment (2014) he and his team performed and ultra-precise test of CPT invariance with baryons by comparing the proton-to-antiproton charge-to-mass ratio with a fractional precision of 69 parts in a trillion. He invented a reservoir trap technique, which enables BASE to operate antiproton experiments independent of accelerator cycles, and demonstrated trapping of antiprotons for more than 405 days. In 2017 BASE reported on the most precise measurement of the magnetic moment of the antiproton with a fractional precision of 1.5 parts in a billion, a measurement which determined for the first time an antimatter property more precisely than that of its matter counterpart. Together with an 11-fold improved proton magnetic moment measurement performed afterwards at the BASE-Mainz experiment, this measurement improves the previous best baryon moment CPT test by a factor of 3000. Recently his group was setting first laboratory limits on the interaction of antiprotons with dark matter. For his work on high-precision comparisons of the fundamental properties of protons and antiprotons he received the 2014 IUPAP young scientist award for fundamental metrology.