Observation of a correlated free four-neutron system

M. Duer , T. Aumann , R. Gernhäuser , V. Panin , S. Paschalis , D.M. Rossi , N.L. Achouri (1) , D. Ahn , H. Baba , C.A. Bertulani , M. Böhmer , K. Boretzky , C. Caesar , N. Chiga , A. Corsi (2) , D. Cortina-Gil , C.A. Douma , F. Dufter , Z. Elekes , J. Feng , B. Fernández-Domínguez , U. Forsberg , N. Fukuda , I. Gasparic , Z. Ge , J.M. Gheller (2) , J. Gibelin (1) , A. Gillibert (2) , K.I. Hahn , Z. Halász , M.N. Harakeh , A. Hirayama , M. Holl , N. Inabe , T. Isobe , J. Kahlbow , N. Kalantar-Nayestanaki , D. Kim , S. Kim , T. Kobayashi , Y. Kondo , D. Körper , P. Koseoglou , Y. Kubota , I. Kuti , P.J. Li , C. Lehr , S. Lindberg , Y. Liu , F.M. Marqués (1) , S. Masuoka , M. Matsumoto , J. Mayer , K. Miki , B. Monteagudo (1) , T. Nakamura , T. Nilsson , A. Obertelli (2) , N.A. Orr (1) , H. Otsu , S.Y. Park , M. Parlog (1) , P.M. Potlog , S. Reichert , A. Revel (3, 1, 2) , A.T. Saito , M. Sasano , H. Scheit , F. Schindler , S. Shimoura , H. Simon , L. Stuhl , H. Suzuki , D. Symochko , H. Takeda , J. Tanaka , Y. Togano , T. Tomai , H.T. Törnqvist , J. Tscheuschner , T. Uesaka , V. Wagner , H. Yamada , B. Yang , L. Yang , Z.H. Yang , M. Yasuda , K. Yoneda , L. Zanetti , J. Zenihiro , M.V. Zhukov

1 LPCC - Laboratoire de physique corpusculaire de Caen
2 IRFU - Institut de Recherches sur les lois Fondamentales de l'Univers
3 GANIL - Grand Accélérateur National d'Ions Lourds

AbstractA long-standing question in nuclear physics is whether chargeless nuclear systems can exist. To our knowledge, only neutron stars represent near-pure neutron systems, where neutrons are squeezed together by the gravitational force to very high densities. The experimental search for isolated multi-neutron systems has been an ongoing quest for several decades1, with a particular focus on the four-neutron system called the tetraneutron, resulting in only a few indications of its existence so far2–4, leaving the tetraneutron an elusive nuclear system for six decades. Here we report on the observation of a resonance-like structure near threshold in the four-neutron system that is consistent with a quasi-bound tetraneutron state existing for a very short time. The measured energy and width of this state provide a key benchmark for our understanding of the nuclear force. The use of an experimental approach based on a knockout reaction at large momentum transfer with a radioactive high-energy 8He beam was key.

Domaines: Physique Nucléaire Expérimentale [nucl-ex]

M. Duer, T. Aumann, R. Gernhäuser, V. Panin, S. Paschalis, et al.. Observation of a correlated free four-neutron system. Nature, 2022, 606 (7915), pp.678-682. ⟨10.1038/s41586-022-04827-6⟩. ⟨hal-03705487⟩