https://doi.org/10.1140/epja/s10050-020-00294-7
Regular Article – Experimental Physics
Signature of a possible
-cluster state in
doubly-magic
Ni
1
KVI-CART, University of Groningen, NL-9747 AA, Groningen, The Netherlands
2
GSI Helmholtzzentrum für Schwerionenforschung GmbH, 64291, Darmstadt, Germany
3
Department of Physics, Konan University, 658-8501, Kobe, Japan
4
LPC Caen, ENSICAEN, Université de Caen, CNRS/IN2P3, Caen, France
5
GANIL, CEA/DRF-CNRS/IN2P3, Bvd Henri Becquerel, 14076, Caen, France
6
Universidade de Santiago de Compostela, 15706, Santiago de Compostela, Spain
7
Research Center for Nuclear Physics, Osaka University, 567-0047, Osaka, Japan
8
Physics Department, University of Notre Dame, 46556, Notre Dame, IN, USA
9
IJCLab, Université Paris-Saclay, CNRS/IN2P3, 91405, Orsay Cedex, France
10
Institute of Nuclear Research (ATOMKI), P.O. Box 51, 4001, Debrecen, Hungary
11
G.N. Flerov Laboratory of Nuclear Reactions, Joint Institute for Nuclear Research, Dubna, 144980, Moscow oblast, Russia
12
National Research Nuclear Center, Moscow Engineering Physics Institute, Kashirskoe sh. 31, 115409, Moscow, Russia
13
Institute of Nuclear Physics PAN, ul. Radzikowskiego 152, 31-342, Kraków, Poland
14
Instituut voor Kern- en Stralingsfysica, KU Leuven, 3001, Leuven, Belgium
15
IPN Orsay, Université Paris Sud, IN2P3-CNRS, 91406, Orsay Cedex, France
16
Irfu, CEA, Université Paris-Saclay, 91191, Gif-sur-Yvette, France
17
SCK CEN, Boeretang 200, 2400, Mol, Belgium
18
Indian Institute of Technology (Indian School of Mines), 826004, Dhanbad, Jharkhand, India
Received:
28
April
2020
Accepted:
28
October
2020
Published online:
12
November
2020
An inelastic -scattering experiment on the unstable
, doubly-magic
Ni nucleus was performed in inverse kinematics at an incident energy of 50 A.MeV at GANIL. High multiplicity for
-particle emission was observed within the limited phase-space of the experimental setup. This observation cannot be explained by means of the statistical-decay model. The ideal classical gas model at kT = 0.4 MeV reproduces fairly well the experimental momentum distribution and the observed multiplicity of
particles corresponds to an excitation energy around 96 MeV. The method of distributed
-decay ensembles is in agreement with the experimental results if we assume that the
-gas state in
Ni exists at around
MeV. These results suggest that there may exist an exotic state consisting of many
particles at the excitation energy of
MeV.
© Società Italiana di Fisica and Springer-Verlag GmbH Germany, part of Springer Nature 2020