H. Breuker

The ASACUSA antihydrogen and hydrogen program: results and prospects

The goal of the ASACUSA-CUSP collaboration at the Antiproton Decelerator of CERN is to measure the ground-state hyperfine splitting of antihydrogen using an atomic spectroscopy beamline. A milestone was achieved in 2012 through the detection of 80 antihydrogen atoms 2.7u2009m away from their production region. This was the first observation of ‘cold’ antihydrogen in a magnetic field free region. In parallel to the progress on the antihydrogen production, the spectroscopy beamline was tested with a source of hydrogen. This led to a measurement at a relative precision of 2.7×10−9 which constitutes the most precise measurement of the hydrogen hyperfine splitting in a beam. Further measurements with an upgraded hydrogen apparatus are motivated by CPT and Lorentz violation tests in the framework of the Standard Model Extension. Unlike for hydrogen, the antihydrogen experiment is complicated by the difficulty of synthesizing enough cold antiatoms in the ground state. The first antihydrogen quantum states scan at the entrance of the spectroscopy apparatus was realized in 2016 and is presented here. The prospects for a ppm measurement are also discussed. This article is part of the Theo Murphy meeting issue ‘Antiproton physics in the ELENA era’.

Towards measuring the ground state hyperfine splitting of antihydrogen – a progress report

We report the successful commissioning and testing of a dedicated field-ioniser chamber for measuring principal quantum number distributions in antihydrogen as part of the ASACUSA hyperfine spectroscopy apparatus. The new chamber is combined with a beam normalisation detector that consists of plastic scintillators and a retractable passivated implanted planar silicon (PIPS) detector.

The development of the antihydrogen beam detector and the detection of the antihydrogen atoms for in-flight hyperfine spectroscopy

We have been developing ground-state antihydrogen atomic beams to test CPT symmetry via in-flight hyperfine spectroscopy. A new antihydrogen beam detector has been developed. The overview of the experiment, the detail of the detector and latest results will be presented.

Antihydrogen Synthesis in a Double-Cusp Trap

Naofumi Kuroda1, Minori Tajima1,2, Balint Radics2, Pierre Dupré2, Yugo Nagata3, Chikato Kaga4, Yasuyuki Kanai2, Marco Leali5,6, Evandro Lodi Rizzini5,6, Valerio Mascagna5,6, Takuya Matsudate1, Horst Breuker7, Hiroyuki Higaki4, Yasuyuki Matsuda1, Stefan Ulmer8, Luca Venturelli5,6, and Yasunori Yamazaki2 1Institute of Physics, Graduate School of Arts and Sciences, University of Tokyo, 3-8-1 Komaba, Meguro-ku, Tokyo 153-8901, Japan 2Atomic Physics Research Unit, RIKEN, 2-1 Hirosawa, Wako-shi, Saitama 351-0198, Japan 3Department of Applied Physics, Tokyo Univeristy of Agriculture and Technology, 2-24-16 Nakacho, Koganei-shi, Tokyo 184-8588, Japan 4Graduate School of Advanced Sciences of Matter, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8530, Japan 5Dipartmento di Ingegneria dell’Informazione, Università di Brescia, Brescia 25133, Italy 6INFN, Gruppo Collegato di Brescia, Brescia 25133, Italy 7CERN, Genève 1211, Switzerland 8Ulmer Initiative Research Unit, RIKEN, 2-1 Hirosawa, Wako-shi, Saitama 351-0198, Japan

Physical Society of Japan : Manipulation and transport of antiprotons for an efficient production of antihydrogen atoms

Minori Tajima1,2, Naofumi Kuroda1, Pierre Dupre2, Yugo Nagata2,3, Balint Radics2, Takuya Matsudate1, Marco Leali4, Valerio Mascagna4, Luca Venturelli4, Horst Breuker5, Hiroyuki Higaki6, Yasuyuki Kanai2, Evandro Lodi Rizzini4, Yasuyuki Matsuda1, Stefan Ulmer7 and Yasunori Yamazaki2 1The University of Tokyo, 3-8-1 Komaba, Meguro, Tokyo 153-8902, Japan 2Atomic Physics Research Unit, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan 3Department of Applied Physics, Tokyo University of Agriculture and Technology, Koganei, Tokyo 184-8588, Japan 4University of Brescia, 15 Piazza del Mercato, Brescia BS 25121, Italy 5CERN, 23 Geneva, CH 1211, Switzerland 6Hiroshima University, 1-2-3 Kagamiyama, Higashihiroshima, Hiroshima 739-8530, Japan 7Ulmer Initiative Research Unit, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan

Monte-Carlo based performance assessment of ASACUSA’s antihydrogen detector

Abstract An antihydrogen detector consisting of a thin BGO disk and a surrounding plastic scintillator hodoscope has been developed. We have characterized the two-dimensional positions sensitivity of the thin BGO disk and energy deposition into the BGO was calibrated using cosmic rays by comparing experimental data with Monte-Carlo simulations. The particle tracks were defined by connecting BGO hit positions and hits on the surrounding hodoscope scintillator bars. The event rate was investigated as a function of the angles between the tracks and the energy deposition in the BGO for simulated antiproton events, and for measured and simulated cosmic ray events. Identification of the antihydrogen Monte Carlo events was performed using the energy deposited in the BGO and the particle tracks. The cosmic ray background was limited to 12xa0mHz with a detection efficiency of 81%. The signal-to-noise ratio was improved from 0.22xa0 s − 1 ∕ 2 obtained with the detector in 2012 to 0.26xa0 s − 1 ∕ 2 in this work.

Measurements and 3D Reconstruction of Antimatter Annihilations with the ASACUSA Micromegas Tracker

B. Radics1,2, H. Breuker3, P. Dupre1, Y. Higashi4, C. Kaga5, M. Leali6, E. Lodi Rizzini6, V. Mascagna6, T. Matsudate4, D.J. Murtagh1, M. Tajima4, H.A. Torii4, S. Van Gorp1, H. Higaki5, T.Y. Kanai1, N. Kuroda4, Y. Matsuda4, S. Ulmer1, L. Venturelli6, Y. Yamazaki1,4 1Atomic Physics Laboratory, RIKEN, Saitama 351-0198, Japan 2ETH Zurich, Institute for Particle Physics, CH-8093 Zürich, Switzerland 3CERN, Genéve 1211, Switzerland 4Graduate School of Arts and Sciences, University of Tokyo, Tokyo 153-8902, Japan 5Graduate School of Advanced Sciences of Matter, Hiroshima University, Hiroshima 739-8530, Japan 6Dipartimento di Ingegneria dell’Informazione, Università di Brescia & INFN, Gruppo Collegato di Brescia, 25133, Brescia, Italy 7Department of Applied Physics, Tokyo University of Agriculture and Technology, Tokyo, 184-8588, Japan