First operation of the FAMU experiment at the RIKEN-RAL high intensity muon beam facility

Abstract The FAMU experiment, supported and funded by the Italian Institute of Nuclear Physics (INFN) and by the Science and Technology Facilities Council (STFC), aims to perform the first measurement of the ground-state hyperfine splitting ( 1S-hfs ) of muonic hydrogen ( $$\mu H$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mi>μ</mml:mi> <mml:mi>H</mml:mi> </mml:mrow> </mml:math> ). This quantity is highly sensitive to the proton’s Zemach radius $$R_Z$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msub> <mml:mi>R</mml:mi> <mml:mi>Z</mml:mi> </mml:msub> </mml:math> . An experimental determination of $$R_Z$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msub> <mml:mi>R</mml:mi> <mml:mi>Z</mml:mi> </mml:msub> </mml:math> provides significant constraints on the parametrisation of the proton form factors as well as on theoretical models describing the proton’s electromagnetic structure. Following years of technological and methodological development, the FAMU experiment began operations in 2023 at Port 1 of the RIKEN-RAL muon beam line at the ISIS Neutron and Muon Source facility (Didcot, UK). In this paper, we first describe the unique detection technique employed by FAMU to determine the 1S-hfs of muonic hydrogen, followed by a detailed presentation of the final experimental layout. Finally, we report the first outcome from the 2023 commissioning run and from the initial physics runs performed in 2023 and 2024.

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Publication Details

Journal
The European Physical Journal A
Published
2025-12-24
DOI
https://doi.org/10.1140/epja/s10050-025-01758-4
Citations
1
Primary Topic
Muon and positron interactions and applications
Type
article
Field-Weighted Citation Impact
0.86

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article

First operation of the FAMU experiment at the RIKEN-RAL high intensity muon beam facility

R. Rossini, Alessandro Menegolli, Roberta Ramponi, M. Baruzzo et al.
1 citations
The European Physical Journal A
Muon and positron interactions and applications
0.86
article

First operation of the FAMU experiment at the RIKEN-RAL high intensity muon beam facility

R. Rossini, Alessandro Menegolli, Roberta Ramponi, M. Baruzzo, Guido Toci, K. Yokoyama, E. Vallazza, R. Gaigher, A. Vacchi, M. Danailov, L. Tortora, G. Morgante, S. Capra, M. Clemenza, S. Monzani, L. Gianfrani, H. Eduardo Roman, Petar Danev, Lorenzo Colace, A. Sbrizzi, G. Baldazzi, M. Rossella, Eugenio Fasci, M. Stoilov, M. Pullia, J. S. Lord, A. Adamczak, D. Bakalov, D. Cirrincione, R. Benocci, A. Pullia, M. Bonesini, José J. Suárez-Vargas, A. de Bari, C. Pizzolotto, C. De Vecchi, A. D. Hillier, R. Bertoni, Luigi Moretti, D. Di Ferdinando, E. Mocchiutti, Katsu Ishida
article en
1 citations

Abstract

Abstract The FAMU experiment, supported and funded by the Italian Institute of Nuclear Physics (INFN) and by the Science and Technology Facilities Council (STFC), aims to perform the first measurement of the ground-state hyperfine splitting ( 1S-hfs ) of muonic hydrogen ( $$\mu H$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mi>μ</mml:mi> <mml:mi>H</mml:mi> </mml:mrow> </mml:math> ). This quantity is highly sensitive to the proton’s Zemach radius $$R_Z$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msub> <mml:mi>R</mml:mi> <mml:mi>Z</mml:mi> </mml:msub> </mml:math> . An experimental determination of $$R_Z$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msub> <mml:mi>R</mml:mi> <mml:mi>Z</mml:mi> </mml:msub> </mml:math> provides significant constraints on the parametrisation of the proton form factors as well as on theoretical models describing the proton’s electromagnetic structure. Following years of technological and methodological development, the FAMU experiment began operations in 2023 at Port 1 of the RIKEN-RAL muon beam line at the ISIS Neutron and Muon Source facility (Didcot, UK). In this paper, we first describe the unique detection technique employed by FAMU to determine the 1S-hfs of muonic hydrogen, followed by a detailed presentation of the final experimental layout. Finally, we report the first outcome from the 2023 commissioning run and from the initial physics runs performed in 2023 and 2024.

The European Physical Journal AVol. 61(12)
Roma Tre University (IT), Rutherford Appleton Laboratory (GB), University of Udine (IT), University of Milan (IT), Bulgarian Academy of Sciences (BG), Elettra-Sincrotrone Trieste S.C.p.A. (IT), National Center for Oncological Hadrontherapy (IT), Institute of Nuclear Physics, Polish Academy of Sciences (PL), Istituto Nazionale di Fisica Nucleare, Sezione di Napoli (IT), Istituto Nazionale di Fisica Nucleare, Sezione di Pavia (IT), Institute for Nuclear Research and Nuclear Energy (BG), University of Campania "Luigi Vanvitelli" (IT), Istituto Nazionale di Fisica Nucleare, Sezione di Milano (IT), Istituto Nazionale di Fisica Nucleare, Sezione di Milano Bicocca (IT), Istituto Nazionale di Fisica Nucleare, Sezione di Bologna (IT), Istituto Nazionale di Fisica Nucleare, Sezione di Trieste (IT), RIKEN Nishina Center (JP), University of Milano-Bicocca (IT), National Institute for Astrophysics (IT), University of Bologna (IT), Politecnico di Milano (IT)
Florida Agricultural and Mechanical University, Abdus Salam International Centre for Theoretical Physics, Università degli Studi di Pavia, Science and Technology Facilities Council, RIKEN, Nuclear Physics
Openalex Percentile: Top 24%
Muon and positron interactions and applications
0.86
DOIOpen Access PDFOpenAlex
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