Chairs
Professor Jeffrey S. Hangst, Aarhus University
Professor Jeffrey S. Hangst, Aarhus University
Jeffrey S. Hangst is a graduate of MIT (SB, SM) and of the University of Chicago (PhD). He worked at Fermilab and at Argonne while doing his PhD at Chicago. He moved to Aarhus University in Denmark in 1994 and has been there since. Hangst received the European Physical Society's 1996 accelerator award for a young scientist for his work on laser cooling of stored ion beams in the ASTRID storage ring in Aarhus. He has been stationed at CERN full-time since 2001. He is a founding member of the ATHENA antihydrogen collaboration and was the Physics Coordinator of the experiment that produced the first cold antihydrogen atoms at the CERN Antiproton Decelerator (AD) in 2002. This breakthrough was featured on the cover of the New York Times. He is the founder and Spokesperson of the ALPHA collaboration, which demonstrated trapping of antihydrogen atoms in 2010, and the first laser spectroscopy of antihydrogen in 2016. ALPHA’s trapping of antihydrogen was voted ‘Physics Breakthrough of the Year’ by Physics World magazine in 2010. Hangst was elected to fellowship of the American Physical Society, Division of Plasma Physics, in 2005. He received the John Dawson award for excellence in plasma physics from the APS in 2011, and the Ångstrom medal from Uppsala University in 2013 for his work on trapped antihydrogen. He currently holds an elite Advanced Grant (2013-2018) from the European Research Council, and in 2016, he was awarded a prestigious Semper Ardens grant from the Carlsberg Foundation to pursue work on gravitational studies of antimatter.
09:00-09:30
Challenging the Standard Model by the precise comparisons of the fundamental properties of protons and antiprotons.
Dr Stefan Ulmer, RIKEN, Japan
Abstract
The Standard Model (SM) of particle physics is known to be incomplete. This inspires various searches for physics beyond, among them are tests of charge, parity, time (CPT) invariance that compare the fundamental properties of matter/antimatter conjugates at low energy and with high precision.
The Japanese/German BASE collaboration at the antiproton decelerator of CERN targets high-precision comparisons of the fundamental properties of antiprotons and protons, namely, charge-to-mass ratios and magnetic moments. To perform these tests we have developed an advanced Penning trap spectrometer which enabled the most precise measurement of the proton magnetic moment with a fractional precision of 3.3 parts in a billion, the most precise comparison of the proton-to-antiproton charge-to-mass ratio, with a fractional precision of 69 parts in a trillion, as well as the most precise measurement of the magnetic moment of the antiproton (0.8 p.p.m). Recent improvements in the stability of the apparatus enabled us to observe single antiproton spin transitions, based on this achievement a 100-fold improved measurement of the antiproton magnetic moment will become possible. This talk will summarise our most recent results and give an overview on the perspectives of BASE in the ELENA era.
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Dr Stefan Ulmer, RIKEN, Japan
Dr Stefan Ulmer, RIKEN, Japan
Stefan Ulmer is a chief scientist at RIKEN, Japan, founder and spokesperson of CERN’s BASE collaboration. He has received his PhD degree for the “first observation of spin flips with a single trapped proton”, which was a milestone experiment in proton/antiproton magnetic moment measurements. Following his work the BASE collaboration performed the most precise measurement of the magnetic moment of the proton with a fractional precision of 3 parts in a billion. In 2012 he joined the ASACUSA antihydrogen effort as a post-doc where he contributed to the production of the first beam of antihydrogen atoms, setting up the BASE experiment in parallel. In the first run of the BASE experiment (2014) he and his team performed the most 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 in 2016 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 0.8 parts in a million. Very recently, BASE published a paper on the first observation of single antiproton spin transitions, which is a major step towards a measurement of the antiproton magnetic moment with a fractional precision on the parts-per-billion level. For his work on high-precision comparisons of the fundamental properties of protons and antiprotons he received the IUPAP young scientist award 2014.
10:15-10:45
GBAR: leading the dance with ELENA's antiprotons
Dr Pauline Comini, ETH Zürich, Switzerland
Abstract
In order to observe the free fall of antihydrogen atoms, hence measuring the gravitational acceleration of antimatter on Earth, the GBAR experiment aims at producing these antiatoms with velocity of a few m.s-1. This will be achieved by implementing the sympathetic cooling of antihydrogen positive ions, an original idea proposed by J. Walz & T. Hänsch.
In its race toward ultracold antihydrogen atoms, GBAR has found a precious and necessary partner in the new antiproton decelerator ring, ELENA. This talk begins with a review of the different stages allowing GBAR to transform the 100 keV ELENA antiprotons into neV antihydrogen atoms, with particular attention to the ELENA parameters that influence most the design of the experiment.
As ELENA’s first user, GBAR is currently getting ready to receive the first 100 keV antiprotons. The present status of the installation in the AD hall and the planning of the coming years are then detailed. The recording of GBAR’s first antihydrogen free falls will provide a 1% precision on the measurement of g ̅; in order to further improve this precision to 0.01%, a future upgrade of the experiment is already being studied.
Finally, it is worth noting that each antiproton bunch delivered by ELENA to GBAR also bears the potentiality of a few hundreds of antihydrogen atoms, while a large part of the antiprotons remains untouched. Ideas proposed to exploit these beams are also sketched.
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Dr Pauline Comini, ETH Zürich, Switzerland
Dr Pauline Comini, ETH Zürich, Switzerland
Pauline Comini obtained her PhD from the Université Pierre et Marie Curie in 2014 on the production of antihydrogen atoms and ions in the GBAR experiment. For this study, she worked with three institutes for the collaboration: the CEA-Saclay, hosting the project, the Institut de Physique et de Chimie des Matériaux from Strasbourg (IPCMS), for the cross section calculations of the atomic processes involved in GBAR, and the Laboratoire Kastler-Brossel (LKB) in Paris, for the assembly of a laser dedicated to positronium excitation.
Her doctoral thesis was awarded the 2014 Daniel Guinier price for young physicists by the French Physical Society, and the theoretical part, published in 2013 in New Journal of Physics, was selected in the "Highlights of the year" by the journal. In 2015, as a postdoc at ETH Zurich, she worked on the direct two-photon excitation of positronium to Rydberg states, in preparation for subsequent Stark deceleration. Since 2016, she is a permanent physicist in the GBAR group at CEA-Saclay, focusing on the optimisation of the reaction chamber for the antiproton-positronium interaction.
11:00-11:30
The ELENA facility
Dr Christian Carli, CERN, Switzerland
Abstract
The CERN Antiproton Decelerator AD provides antiproton beams with a kinetic energy of 5.3 MeV to an active users community. This extraction energy is the lowest one possible under good conditions with the given circumference of the AD.
The Extra Low Energy Antiproton ring (ELENA) is a small synchrotron with a circumference a factor 6 smaller than the AD to further decelerate antiprotons from the AD from 5.3 MeV to 100 keV. Controlled deceleration in a synchrotron equipped with an electron cooler to reduce emittances in all three planes will allow the existing AD experiments to increase substantially their antiproton capture efficiencies and render new experiments possible.
ELENA ring commissioning is taking place at present and first beams to a new experiment installed in a new experimental area are foreseen this year. The transfer lines from ELENA to existing experiments in the old experimental area will be installed during CERN long Shutdown 2 (LS2) in 2019 and 2020. The status of the project and ring commissioning will be reported.
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Dr Christian Carli, CERN, Switzerland
Dr Christian Carli, CERN, Switzerland
Christian Carli is working as accelerator physicist at CERN. He has contributed to the I-LHC project to upgrade the CERN ion accelerator chain to provide lead ion beams for the LHC and, in particular, led the commissioning of the Low Energy Ion Ring LEIR, the exploitation and improvements of the PS Booster and commissioning of the Antiproton Decelerator AD. He has contributed to the I-LHC project to upgrade the CERN ion accelerator chain to provide lead ion beams for the LHC and, in particular, led the commissioning of the Low Energy Ion Ring LEIR. Furthermore, he has contributed to the exploitation and improvements of the PS Booster and the commissioning of the Antiproton Decelerator AD.