@article {94, title = {Measurement of the principal quantum number distribution in a beam of antihydrogen atoms}, volume = {75}, year = {2021}, month = {2021/03/08}, pages = {91}, abstract = {The ASACUSA (Atomic Spectroscopy And Collisions Using Slow Antiprotons) collaboration plans to measure the ground-state hyperfine splitting of antihydrogen in a beam at the CERN Antiproton Decelerator with initial relative precision of $$10^{-6}$$or better, to test the fundamental CPT (combination of charge conjugation, parity transformation and time reversal) symmetry between matter and antimatter. This challenging goal requires a polarised antihydrogen beam with a sufficient number of antihydrogen atoms in the ground state. The first measurement of the quantum state distribution of antihydrogen atoms in a low magnetic field environment of a few mT is described. Furthermore, the data-driven machine learning analysis to identify antihydrogen events is discussed.}, isbn = {1434-6079}, url = {https://doi.org/10.1140/epjd/s10053-021-00101-y}, author = {Kolbinger, B. and Amsler, C. and Cuendis, S. Arguedas and Breuker, H. and Capon, A. and Costantini, G. and Dupre, P. and Fleck, M. and Gligorova, A. and Higaki, H. and Kanai, Y. and Kletzl, V. and Kuroda, N. and Lanz, A. and Leali, M. and M{\"a}ckel, V. and Malbrunot, C. and Mascagna, V. and Massiczek, O. and Matsuda, Y. and Murtagh, D. J. and Nagata, Y. and Nanda, A. and Nowak, L. and Radics, B. and Sauerzopf, C. and Simon, M. C. and Tajima, M. and Torii, H. A. and Uggerh{\o}j, U. and Ulmer, S. and Venturelli, L. and Weiser, A. and Wiesinger, M. and Widmann, E. and Wolz, T. and Yamazaki, Y. and Zmeskal, J.} } @article {78, title = {Antihydrogen synthesis in a double-CUSP trap towards test of the CPT-symmetry}, journal = {Hyperfine Interactions}, volume = {237}, year = {2016}, pages = {156}, abstract = {

The aim of the ASACUSA-CUSP experiment at CERN is to produce a cold, polarised antihydrogen beam and perform a high precision measurement of the ground-state hyperfine transition frequency of the antihydrogen atom and compare it with that of the hydrogen atom using the same spectroscopic beam line. Towards this goal a significant step was successfully accomplished: synthesised antihydrogen atoms have been produced in a CUSP magnetic configuration and detected at the end of our spectrometer beam line in 2012 [1]. During a long shut down at CERN the ASACUSA-CUSP experiment had been renewed by introducing a new double-CUSP magnetic configuration and a new semi-cylindrical tracking detector (AMT) [2], and by improving the transport feature of low energy antiproton beams. The new tracking detector monitors the antihydrogen synthesis during the mixing cycle of antiprotons and positrons. In this work the latest results and improvements of the antihydrogen synthesis will be presented including highlights from the last beam time.

}, issn = {1572-9540}, doi = {10.1007/s10751-016-1368-4}, url = {http://dx.doi.org/10.1007/s10751-016-1368-4}, author = {Radics, B. and Ishikawa, S. and Kuroda, N. and Murtagh, D. J. and Nagata, Y. and Tajima, M. and Van Gorp, S. and Abo, Y. and Dupre, P. and Higashi, Y. and Kaga, C. and Leali, M. and Mascagna, V. and Venturelli, L. and Zurlo, N. and Breuker, H. and Higaki, H. and Kanai, Y. and Rizzini, E. Lodi and Matsuda, Y. and Ulmer, S. and Yamazaki, Y.} } @article {80, title = {Towards measuring the ground state hyperfine splitting of antihydrogen {\textendash} a progress report}, journal = {Hyperfine Interactions}, volume = {237}, year = {2016}, month = {Jun}, pages = {103}, abstract = {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.}, issn = {1572-9540}, doi = {10.1007/s10751-016-1309-2}, url = {https://doi.org/10.1007/s10751-016-1309-2}, author = {Sauerzopf, C. and Capon, A. A. and Diermaier, M. and Dupre, P. and Higashi, Y. and Kaga, C. and Kolbinger, B. and Leali, M. and Lehner, S. and Rizzini, E. Lodi and Malbrunot, C. and Mascagna, V. and Massiczek, O. and Murtagh, D. J. and Nagata, Y. and Radics, B. and Simon, M. C. and Suzuki, K. and Tajima, M. and Ulmer, S. and Vamosi, S. and Gorp, S. van and Zmeskal, J. and Breuker, H. and Higaki, H. and Kanai, Y. and Kuroda, N. and Matsuda, Y. and Venturelli, L. and Widmann, E. and Yamazaki, Y.} } @article {75, title = {The ASACUSA CUSP: an antihydrogen experiment}, journal = {Hyperfine Interactions}, volume = {235}, year = {2015}, pages = {13{\textendash}20}, abstract = {In order to test CPT symmetry between antihydrogen and its counterpart hydrogen, the ASACUSA collaboration plans to perform high precision microwave spectroscopy of ground-state hyperfine splitting of antihydrogen atom in-flight. We have developed an apparatus ({\textquoteleft}{\textquoteleft}cusp trap{\textquoteright}{\textquoteright}) which consists of a superconducting anti-Helmholtz coil and multiple ring electrodes. For the preparation of slow antiprotons and positrons, Penning-Malmberg type traps were utilized. The spectrometer line was positioned downstream of the cusp trap. At the end of the beamline, an antihydrogen beam detector was located, which comprises an inorganic Bismuth Germanium Oxide (BGO) single-crystal scintillator housed in a vacuum duct and surrounding plastic scintillators. A significant fraction of antihydrogen atoms flowing out the cusp trap were detected.}, issn = {1572-9540}, doi = {10.1007/s10751-015-1205-1}, url = {http://dx.doi.org/10.1007/s10751-015-1205-1}, author = {Kuroda, N. and Ulmer, S. and Murtagh, D. J. and Gorp, S. and Nagata, Y. and Diermaier, M. and Federmann, S. and Leali, M. and Malbrunot, C. and Mascagna, V. and Massiczek, O. and Michishio, K. and Mizutani, T. and Mohri, A. and Nagahama, H. and Ohtsuka, M. and Radics, B. and Sakurai, S. and Sauerzopf, C. and Suzuki, K. and Tajima, M. and Torii, H. A. and Venturelli, L. and W{\"u}nschek, B. and Zmeskal, J. and Zurlo, N. and Higaki, H. and Kanai, Y. and Rizzini, E. Lodi and Nagashima, Y. and Matsuda, Y. and Widmann, E. and Yamazaki, Y.} } @article {70, title = {The ASACUSA Micromegas Tracker: A cylindrical, bulk Micromegas detector for antimatter research}, journal = {Review of Scientific Instruments}, volume = {86}, year = {2015}, abstract = {

The ASACUSA Micromegas Tracker (AMT; ASACUSA: Atomic Spectroscopy and Collisions Using Slow Antiprotons) was designed to be able to reconstruct antiproton-nucleon annihilation vertices in three dimensions. The goal of this device is to study antihydrogen formation processes in the ASACUSA cusp trap, which was designed to synthesise a spin-polarised antihydrogen beam for precise tests of Charge, Parity, and Time (CPT) symmetry invariance. This paper discusses the structure and technical details of an AMT detector built into such an environment, its data acquisition system and the first performance with cosmic rays.

}, doi = {http://dx.doi.org/10.1063/1.4927685}, url = {http://scitation.aip.org/content/aip/journal/rsi/86/8/10.1063/1.4927685}, author = {Radics, B. and Nagata, Y. and Yamazaki, Y. and Ishikawa, S. and Kuroda, N. and Matsuda, Y. and Anfreville, M. and Aune, S. and Boyer, M. and Chateau, F. and Combet, M. and Granelli, R. and Legou, P. and Mandjavidze, I. and Procureur, S. and Riallot, M. and Vallage, B. and Vandenbroucke, M.} } @article {68, title = {Scaling behavior of the ground-state antihydrogen yield as a function of positron density and temperature from classical-trajectory Monte Carlo simulations}, journal = {Phys. Rev. A}, volume = {90}, year = {2014}, month = {Sep}, pages = {032704}, doi = {10.1103/PhysRevA.90.032704}, url = {http://link.aps.org/doi/10.1103/PhysRevA.90.032704}, author = {Radics, B. and Murtagh, D. J. and Yamazaki, Y. and Robicheaux, F.} } @article {56, title = {A source of antihydrogen for in-flight hyperfine spectroscopy}, journal = {Nat Commun}, volume = {5}, year = {2014}, month = {21/01/2014}, abstract = {

Antihydrogen, a positron bound to an antiproton, is the simplest antiatom. Its counterpart{\textemdash}hydrogen{\textemdash}is one of the most precisely investigated and best understood systems in physics research. High-resolution comparisons of both systems provide sensitive tests of CPT symmetry, which is the most fundamental symmetry in the Standard Model of elementary particle physics. Any measured difference would point to CPT violation and thus to new physics. Here we report the development of an antihydrogen source using a cusp trap for in-flight spectroscopy. A total of 80 antihydrogen atoms are unambiguously detected 2.7 m downstream of the production region, where perturbing residual magnetic fields are small. This is a major step towards precision spectroscopy of the ground-state hyperfine splitting of antihydrogen using Rabi-like beam spectroscopy.

}, url = {http://dx.doi.org/10.1038/ncomms4089}, author = {Kuroda, N. and Ulmer, S. and Murtagh, D. J. and Van Gorp, S. and Nagata, Y. and Diermaier, M. and Federmann, S. and Leali, M. and Malbrunot, C. and Mascagna, V. and Massiczek, O. and Michishio, K. and Mizutani, T. and Mohri, A. and Nagahama, H. and Ohtsuka, M. and Radics, B. and Sakurai, S. and Sauerzopf, C. and Suzuki, K. and Tajima, M. and Torii, H. A. and Venturelli, L. and Wu{\textasciidieresis}nschek, B. and Zmeskal, J. and Zurlo, N. and Higaki, H. and Kanai, Y. and Lodi Rizzini, E. and Nagashima, Y. and Matsuda, Y. and Widmann, E. and Yamazaki, Y.} } @article {67, title = {Spectroscopy apparatus for the measurement of the hyperfine structure of antihydrogen}, journal = {Hyperfine Interactions}, year = {2014}, pages = {1-6}, keywords = {Antihydrogen, CPT symmetry, Hyperfine spectroscopy}, issn = {0304-3843}, doi = {10.1007/s10751-014-1013-z}, url = {http://dx.doi.org/10.1007/s10751-014-1013-z}, author = {Malbrunot, C. and Caradonna, P. and Diermaier, M. and Dilaver, N. and Friedreich, S. and Kolbinger, B. and Lehner, S. and Lundmark, R. and Massiczek, O. and Radics, B. and Sauerzopf, C. and Simon, M. and Widmann, E. and Wolf, M. and W{\"u}nschek, B. and Zmeskal, J.} } @article {66, title = {Towards a spin polarized antihydrogen beam}, journal = {Hyperfine Interactions}, year = {2014}, pages = {1-10}, keywords = {Antihydrogen, Atomic beam, CPT invariance, Rydberg atom}, issn = {0304-3843}, doi = {10.1007/s10751-014-1016-9}, url = {http://dx.doi.org/10.1007/s10751-014-1016-9}, author = {Kuroda, N. and Ulmer, S. and Murtagh, D.J. and Van Gorp, S. and Nagata, Y. and Diermaier, M. and Federmann, S. and Leali, M. and Malbrunot, C. and Mascagna, V. and Massiczek, O. and Michishio, K. and Mizutani, T. and Mohri, A. and Nagahama, H. and Ohtsuka, M. and Radics, B. and Sakurai, S. and Sauerzopf, C. and Suzuki, K. and Tajima, M. and Torii, H.A. and Venturelli, L. and W{\"u}nschek, B. and Zmeskal, J. and Zurlo, N. and Higaki, H. and Kanai, Y. and Lodi-Rizzini, E. and Nagashima, Y. and Matsuda, Y. and Widmann, E. and Yamazaki, Y.} }