Year: 2026
Type: preprint
Abstract: The production of antihydrogen by the GBAR experiment at AD/ELENA requires good knowledge of the number of incident keV antiprotons, which can be problematic. We have used a commercial CMOS digital camera mounted around the experimental vacuum chamber to determine antiproton numbers from ionising particles created in the annihilation process on the surface of microchannel plate detectors which are used for beam imaging. We show that the multiplicity of emerging charged particles is as expected for individual annihilations of antiprotons with nucleons at rest, taking into account the surrounding material budget. Most of those particles are in the minimal ionising regime, but can be detected with nearly 100% efficiency in the CMOS pixel detector, while due to the thin depletion layer the device is insensitive to background gammas. Thanks to the high granularity and small pixel size millions of antiproton annihilations can be reconstructed in a dense tracking environment over a large dynamic range with good resolution. From cluster length studies of non perpendicular tracks the thickness of the depletion zone and effective detection area was estimated. The cluster length also allows for a monitoring of track angles. Antiproton numbers are determined from the number of reconstructed clusters in the CMOS sensor by means of the covered solid angle relative to a calibration measurements with well known beam intensities at the most upstream location of the GBAR apparatus. Material effects on the emerging annihilation products were estimated by Monte Carlo (Geant4) calculations, while annihilation artefacts on the complex surface of a microchannel plate are cancelled out in this approach. This method minimises largely systematic uncertainties, leading to a final error of roughly 10% for the reconstruction of absolute antiproton numbers.
Source: arXiv (Cornell University)
Authors: Regenfus, C., Adrich, P., Belosevic, I., Benkel, F., Chung, M., Cladé, P., Comini, P., Crivelli, P., Debu, P., Douillet, A., Geffroy, S., Guellati-Khelifa, S., Guichard, P., Hervieux, P. -A., Hilico, L., Indelicato, P., Jonsell, S., Karr, J. -P., Kim, B., Kim, S., Kim, E. -S., Kuroda, N., Lee, B., Liszkay, L., Lunney, D., Manfredi, G., Mansoulié, B., Martimort, V., Matusiak, M., Nesvizhevsky, V., Nez, F., Park, K., Paul, N., Perez, E., Pérez, P., Roumegou, C., Roussé, J. -Y., Schmidt-Kaler, F., Szymczyk, K., Tanaka, T. A., Tuchming, B., van der Werf, D. -P., Won, D., Wronka, S., Yzombard, P.
Institutions: ETH Zurich, Institute for Particle Physics and Astrophysics, National Centre for Nuclear Research, Commissariat à l'Énergie Atomique et aux Énergies Alternatives, Université Paris-Saclay, CEA Paris-Saclay - Etablissement de Saclay, Institut de Recherche sur les Lois Fondamentales de l'Univers, Pohang University of Science and Technology, Centre National de la Recherche Scientifique, Collège de France, Université Paris Sciences et Lettres, Laboratoire Kastler Brossel, École Normale Supérieure - PSL, Sorbonne Université, Université d'Évry Val-d'Essonne, Institut National de Physique Nucléaire et de Physique des Particules, Laboratoire de Physique des 2 Infinis Irène Joliot-Curie, Conservatoire National des Arts et Métiers, Institut de Physique et Chimie des Matériaux de Strasbourg, Université de Strasbourg, Stockholm University, Institute for Basic Science, Seoul National University, Korea University, The University of Tokyo, Institut Laue-Langevin, European Organization for Nuclear Research, Swansea University, Johannes Gutenberg University Mainz, National Metrology Institute of Japan, National Institute of Advanced Industrial Science and Technology
Language: English
Subfield: Nuclear and High Energy Physics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
Funders: National Science Foundation, CERN, Deutsche Forschungsgemeinschaft, Agence Nationale de la Recherche, Schweizerischer Nationalfonds zur Förderung der Wissenschaftlichen Forschung, Pohang University of Science and Technology, Ulsan National Institute of Science and Technology, Centre National d’Etudes Spatiales, Eidgenössische Technische Hochschule Zürich, Vetenskapsrådet, Centre National de la Recherche Scientifique, Japan Society for the Promotion of Science, Institut National de Physique Nucléaire et de Physique des Particules
Awards: Gravitational Behaviour of Anti-hydrogen at Rest (GBAR), Determination of the charge radius of antiproton and test of CPT symmetry through the Lamb shift measurement of antihydrogen, G195474297, G2756832313, 重イオンビームフォイル分光研究, G3014852138, Gravitational Behaviour of Anti-hydrogen at Rest (GBAR), Catheter ABlation of Atrial fibrillation versus atrioventricular nodal ablation with CondUction System pacing in persistent atrial fibrillation and heart failure (ABACUS), Study of Exotic Matter, Antihydrogen and few-body physics, Study of exotic atoms by microwave spectroscopy, Exploring stopping power in ion traps, Antihydrogen physics, Study of Positronium-Hydrogen Interactions: Negative hydrogen production Cross-Sections, Antimatter atoms and ions
OpenAlex ID: W7208715637