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From the same journal

Unveiling the two-proton halo character of 17Ne: Exclusive measurement of quasi-free proton-knockout reactions

Research output: Contribution to journalArticlepeer-review


  • C. Lehr
  • F. Wamers
  • F. Aksouh
  • Yu Aksyutina
  • H. Álvarez-Pol
  • L. Atar
  • T. Aumann
  • S. Beceiro-Novo
  • C. A. Bertulani
  • K. Boretzky
  • M. J.G. Borge
  • C. Caesar
  • M. Chartier
  • A. Chatillon
  • L. V. Chulkov
  • D. Cortina-Gil
  • P. Díaz Fernández
  • H. Emling
  • O. Ershova
  • L. M. Fraile
  • H. O.U. Fynbo
  • D. Galaviz
  • H. Geissel
  • M. Heil
  • M. Heine
  • D. H.H. Hoffmann
  • M. Holl
  • H. T. Johansson
  • B. Jonson
  • C. Karagiannis
  • O. A. Kiselev
  • R. Kulessa
  • N. Kurz
  • C. Langer
  • M. Lantz
  • T. Le Bleis
  • R. Lemmon
  • Yu A. Litvinov
  • B. Löher
  • K. Mahata
  • J. Marganiec-Galązka
  • C. Müntz
  • T. Nilsson
  • C. Nociforo
  • W. Ott
  • V. Panin
  • A. Perea
  • R. Plag
  • R. Reifarth
  • A. Richter
  • K. Riisager
  • C. Rodriguez-Tajes
  • D. Rossi
  • D. Savran
  • H. Scheit
  • G. Schrieder
  • P. Schrock
  • H. Simon
  • J. Stroth
  • K. Sümmerer
  • O. Tengblad
  • H. Weick
  • C. Wimmer


Publication details

JournalPhysics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics
DateAccepted/In press - 7 Feb 2022
DateE-pub ahead of print - 22 Feb 2022
DatePublished (current) - 10 Apr 2022
Number of pages6
Early online date22/02/22
Original languageEnglish


The proton drip-line nucleus 17Ne is investigated experimentally in order to determine its two-proton halo character. A fully exclusive measurement of the 17Ne(p,2p)16F→15⁎O+p quasi-free one-proton knockout reaction has been performed at GSI at around 500 MeV/nucleon beam energy. All particles resulting from the scattering process have been detected. The relevant reconstructed quantities are the angles of the two protons scattered in quasi-elastic kinematics, the decay of 16F into 15O (including γ decays from excited states) and a proton, as well as the 15O+p relative-energy spectrum and the 16F momentum distributions. The latter two quantities allow an independent and consistent determination of the fractions of l=0 and l=2 motion of the valence protons in 17Ne. With a resulting relatively small l=0 component of only around 35(3)%, it is concluded that 17Ne exhibits a rather modest halo character only. The quantitative agreement of the two values deduced from the energy spectrum and the momentum distributions supports the theoretical treatment of the calculation of momentum distributions after quasi-free knockout reactions at high energies by taking into account distortions based on the Glauber theory. Moreover, the experimental data allow the separation of valence-proton knockout and knockout from the 15O core. The latter process contributes with 11.8(3.1) mb around 40% to the total proton-knockout cross section of 30.3(2.3) mb, which explains previously reported contradicting conclusions derived from inclusive cross sections.

Bibliographical note

Funding Information:
This work is supported by the German Federal Ministry for Education and Research ( BMBF ) under contract No. 05P15RDFN1 , the ExtreMe Matter Institute (EMMI), HIC for FAIR , and the GSI-TU Darmstadt cooperation agreement. Financial support from the Swedish Research Council , from the Russian Foundation for Basic Research (RFBR Grant 12-02-01115-a ), and from the Spanish grants from MICINN AEI FPA2017-87568-P , PGC2018-0099746-B-C21 , FPA2015-64969-P , PID2019-104390GB-I00 , RTI2018-098868-B-100 , and Maria de Maeztu Units of excellence MDM-2016-0692 are also acknowledged. One of us (B. J.) is a Helmholtz International Fellow. C.A.B. acknowledges support by the U.S. DOE grant DE-FG02-08ER41533 and the U.S. NSF Grant No. 1415656 .

Publisher Copyright:
© 2022 The Author(s)

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