https://doi.org/10.1140/epja/s10050-026-01892-7
Regular Article – Experimental Physics
Studies of stretched M4 resonances in light nuclei via 
-ray and particle spectroscopy
1
Institute of Nuclear Physics PAN, 31-342, Kraków, Poland
2
Dipartimento di Fisica, Università degli Studi di Milano, 20133, Milano, Italy
3
Istituto Nazionale di Fisica Nucleare, 20133, Milano, Italy
4
National Centre for Nuclear Research, Pasteura 7, 02-093, Warsaw, Poland
5
Grand Accélérateur National d’Ions Lourds, CEA/DSM-CNRS/IN2P3, BP 55027, 14076 CAEN Cedex 05, Caen, France
6
“Horia Hulubei” National Institute for Physics and Nuclear Engineering, 077125, Bucharest-Magurele, Romania
7
Nuclear Energy Group, ESRIG, University of Groningen, 9747 AA, Groningen, The Netherlands
8
Université Paris-Saclay, CNRS/IN2P3, 91190, Orsay, France
9
Department of Physics, Université Libre de Bruxelles, 1050, Brussels, Belgium
a
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Received:
5
February
2026
Accepted:
26
May
2026
Published online:
2
July
2026
Abstract
A research program at the Cyclotron Centre Bronowice (CCB) in Kraków has been undertaken to investigate stretched states in p-shell nuclei, i.e., a class of relatively simple nuclear excitations lying in the continuum and characterized by a strong 1d
1p
single particle-hole component in their wave function, coupled to the maximum spin 4
. The states of interest were populated in proton inelastic scattering reactions, at a proton energy of 135 MeV. A detection setup, composed of a number of charged-particle CsI triple telescopes, for scattered-proton detection, coupled to an array of large-volume scintillator detectors for -ray measurements, and a set of double-sided silicon strip detectors for light charged particles detection, was used. Coincident measurements of the scattered protons, providing information on the excitation energies of the target nucleus, and the rays, emitted from the daughter nuclei, allowed to establish the main decay channels of populated stretched states. Results are presented for the first studied cases of 
C and 
O. A comparison is made with recently developed Gamow Shell Model calculations for C, showing that this model is capable of predicting the structure and decay properties of stretched resonances.
Communicated by Wolfram Korten.
© The Author(s) 2026
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