@article {96, title = {Upgrade of ASACUSA{\textquoteright}s antihydrogen detector}, journal = {Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment}, volume = {1045}, year = {2023}, pages = {167568}, abstract = {The goal of the ASACUSA (Atomic Spectroscopy And Collisions Using Slow Antiprotons) CUSP experiment at CERN{\textquoteright}s Antiproton Decelerator is to measure the ground state hyperfine splitting of antihydrogen in order to test whether CPT invariance is broken. The ASACUSA hodoscope is a detector consisting of two layers of 32 plastic scintillator bars individually read out by two serially connected silicon photomultipliers (SiPMs) on each end. Two additional layers for position resolution along the beam axis were scintillator fibres, which will now be replaced by scintillating tiles placed onto the existing bars and also read out by SiPMs. If the antiproton of antihydrogen annihilates in the centre of the hodoscope, particles (mostly pions) are produced and travel through the various layers of the detector and produce signals. The hodoscope was successfully used during the last data taking period at CERN. The necessary time resolution to discriminate between particles travelling through the detector from outside and particles produced in the centre of the detector was achieved by the use of waveform digitisers and software constant fraction discrimination. The disadvantage of this readout scheme was the slow readout speed, which was improved by two orders of magnitude. This was done by omitting the digitisers and replacing them with TDCs reading out the digital time-over-threshold (ToT) signal using leading edge discrimination.}, keywords = {Antihydrogen, antimatter, Data acquisition, Silicon photomultiplier}, issn = {0168-9002}, doi = {https://doi.org/10.1016/j.nima.2022.167568}, url = {https://www.sciencedirect.com/science/article/pii/S0168900222008609}, author = {V. Kraxberger and C. Amsler and H. Breuker and S. Chesnevskaya and G. Costantini and R. Ferragut and M. Giammarchi and A. Gligorova and G. Gosta and H. Higaki and E.D. Hunter and C. Killian and V. Kletzl and N. Kuroda and A. Lanz and M. Leali and V. M{\"a}ckel and G. Maero and C. Malbrunot and V. Mascagna and Y. Matsuda and S. Migliorati and D.J. Murtagh and Y. Nagata and A. Nanda and L. Nowak and E. Pasino and M. Rom{\'e} and M.C. Simon and M. Tajima and V. Toso and S. Ulmer and L. Venturelli and A. Weiser and E. Widmann and T. Wolz and Y. Yamazaki and J. Zmeskal} } @article {90, title = {Monte-Carlo based performance assessment of ASACUSA{\textquoteright}s antihydrogen detector}, journal = {Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment}, volume = {910}, year = {2018}, pages = {90 - 95}, 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 12\ mHz with a detection efficiency of 81\%. The signal-to-noise ratio was improved from 0.22\ s-1/2 obtained with the detector in 2012 to 0.26\ s-1/2 in this work.

}, keywords = {Antihydrogen, antimatter, Calorimeter, Detector, Tracker}, issn = {0168-9002}, doi = {10.1016/j.nima.2018.09.013}, url = {http://www.sciencedirect.com/science/article/pii/S0168900218311227}, author = {Y. Nagata and N. Kuroda and B. Kolbinger and M. Fleck and C. Malbrunot and V. M{\"a}ckel and C. Sauerzopf and M.C. Simon and M. Tajima and J. Zmeskal and H. Breuker and H. Higaki and Y. Kanai and Y. Matsuda and S. Ulmer and L. Venturelli and E. Widmann and Y. Yamazaki} } @article {76, title = {Direct detection of antihydrogen atoms using a BGO crystal}, journal = {Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment}, volume = {840}, year = {2016}, pages = {153 - 159}, abstract = {

Abstract The \{ASACUSA\} collaboration has developed a detector consisting of a large size \{BGO\} crystal to detect an atomic antihydrogen beam, and performed the direct detection of antihydrogen atoms. Energy spectra from antihydrogen annihilation on the \{BGO\} crystal are discussed in comparison to simulation results from the \{GEANT4\} toolkit. Background mainly originating from cosmic rays were strongly suppressed by analyzing the energy deposited in the \{BGO\} and requiring a multiplicity of charged pions. Thus antihydrogen events were identified.

}, keywords = {Antihydrogen, antimatter, Cosmic ray background suppression, Detector, Inorganic scintillator}, issn = {0168-9002}, doi = {http://dx.doi.org/10.1016/j.nima.2016.10.019}, url = {http://www.sciencedirect.com/science/article/pii/S0168900216310440}, author = {Y. Nagata and N. Kuroda and M. Ohtsuka and M. Leali and E. Lodi-Rizzini and V. Mascagna and M. Tajima and H.A. Torii and N. Zurlo and Y. Matsuda and L. Venturelli and Y. Yamazaki} } @article {72, title = {An atomic hydrogen beam to test ASACUSA{\textquoteright}s apparatus for antihydrogen spectroscopy}, journal = {Hyperfine Interactions}, volume = {233}, year = {2015}, pages = {35-40}, keywords = {Antihydrogen, Atomic hydrogen, Ground state hyperfine structure}, issn = {0304-3843}, doi = {10.1007/s10751-015-1151-y}, url = {http://dx.doi.org/10.1007/s10751-015-1151-y}, author = {Diermaier, M. and Caradonna, P. and Kolbinger, B. and Malbrunot, C. and Massiczek, O. and Sauerzopf, C. and Simon, M.C. and Wolf, M. and Zmeskal, J. and Widmann, E.} } @article {71, title = {Towards a precise measurement of the antihydrogen ground state hyperfine splitting in a beam: the case of in-flight radiative decays}, journal = {Journal of Physics B: Atomic, Molecular and Optical Physics}, volume = {48}, year = {2015}, month = {29/07/2015}, pages = {184001}, abstract = {

The ASACUSA antihydrogen setup at the CERN Antiproton Decelerator (AD) consists of an antihydrogen source (cusp magnet coupled to a positron source and an antiproton catching magnet) followed by a spectrometer beamline. After production in the cusp, the antihydrogen atoms decay while they escape the trap leading to changes in their effective magnetic moment which in turn affect their trajectories in the beamline. Those sequential decays in the presence of a varying magnetic field strength from their production point in the cusp to their detection at the end of the spectrometer line can in principle greatly affect the prospects for a precision measurement of the antihydrogen hyperfine splitting given the so-far relatively low number of available anti-atoms. The impact of the antihydrogen decay in this context has for the first time been simulated. The implementation of atomic radiative decay has been done in Geant4 to extend the particle tracking capabilities originally embedded in Geant4 to excited atoms, and to allow studies of the effect of dynamic atomic properties on trajectories. This new tool thus allows the study of particle{\textendash}matter interaction via the Geant4 toolkit while properly taking into account the atomic nature of the object under study. The implementation as well as impacts on the experimental sensitivity for antihydrogen spectroscopy are discussed in this paper.

}, keywords = {Antihydrogen, ground state hyperfine splitting measurement, radiative decay}, url = {http://stacks.iop.org/0953-4075/48/i=18/a=184001}, author = {R Lundmark and C Malbrunot and Y Nagata and B Radics and C Sauerzopf and E Widmann} } @article {69, title = {カスプトラップを用いた反水素研究}, journal = {陽電子科学}, volume = {4}, year = {2015}, month = {Feb.}, pages = {49-59}, chapter = {49}, abstract = {

In this review, we describe a planned experiment of the Atomic Spectroscopy And Collisions Using Slow Antiprotons (ASACUSA) collaboration at CERN to test CPT symmetry via atomic beam spectroscopy of the ground-state hyperfine splitting of antihydrogen using a cusp trap. The cusp trap which consists of a superconducting anti-Helmholtz coil and a stack of ring electrodes, is expected to produce a spin-polarized antihydrogen beam. Recently, the ASACUSA collaboration succeeded in producing antihydrogen atoms in the cusp trap and extracting an antihydrogen beam. This paves the way towards precision in-flight spectroscopy of the antihydrogen atom.

}, keywords = {Antihydrogen, ASACUSA, Atomic beam, CPT symmetry, cusp trap, non-neutral plasma}, author = {Yugo Nagata and Naofumi Kuroda} } @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.} } @article {54, title = {Measurement of the hyperfine structure of antihydrogen in a beam}, journal = {Hyperfine Interactions}, volume = {215}, year = {2013}, pages = {1-8}, keywords = {Antihydrogen, CPT, Precision spectroscopy}, issn = {0304-3843}, doi = {10.1007/s10751-013-0809-6}, url = {http://dx.doi.org/10.1007/s10751-013-0809-6}, author = {Widmann, E. and Diermaier, M. and Juhasz, B. and Malbrunot, C. and Massiczek, O. and Sauerzopf, C. and Suzuki, K. and W{\"u}nschek, B. and Zmeskal, J. and Federmann, S. and Kuroda, N. and Ulmer, S. and Yamazaki, Y.} } @article {50, title = {Antihydrogen atom formation in a CUSP trap towards spin polarized beams}, journal = {Hyperfine Interactions}, volume = {212}, year = {2012}, pages = {31-40}, keywords = {Antihydrogen, Atomic beam, CPT invariance, Rydberg atom}, issn = {0304-3843}, doi = {10.1007/s10751-012-0646-z}, url = {http://dx.doi.org/10.1007/s10751-012-0646-z}, author = {Kuroda, N. and Enomoto, Y. and Michishio, K. and Kim, C.H. and Higaki, H. and Nagata, Y. and Kanai, Y. and Torii, H.A. and Corradini, M. and Leali, M. and Lodi-Rizzini, E. and Venturelli, L. and Zurlo, N. and Fujii, K. and Ohtsuka, M. and Tanaka, K. and Imao, H. and Nagashima, Y. and Matsuda, Y. and Juhasz, B. and Widmann, E. and Mohri, A. and Yamazaki, Y.} } @article {29, title = {ASACUSA MUSASHI: New progress with intense ultra slow antiproton beam}, journal = {Hyperfine Interactions}, volume = {194}, year = {2009}, pages = {71-76}, keywords = {Antihydrogen, Antiproton, Positron}, issn = {0304-3843}, doi = {10.1007/s10751-009-0032-7}, url = {http://dx.doi.org/10.1007/s10751-009-0032-7}, author = {Imao, H. and Tarek, M. and Michishio, K. and Enomoto, Y. and Shimoyama, T. and Kanai, Y. and Kuroda, N. and Mohri, A. and Higaki, H. and Saitoh, H. and Torii, H.A. and Nagata, Y. and Toyoda, H. and Matsuda, Y. and Nagashima, Y. and Yamazaki, Y.} }