2021 Impact factor 3.131
Hadrons and Nuclei

EPJ A Highlight - Achieving high resolution in binary nuclear reactions with outgoing fast neutrons – at last!

To date, the two-nucleon pick-up and stripping counterparts of the (p,t) and (t,p) reactions, the (3He,n) and (n, 3He) reactions, have been poorly investigated due to the difficulty in performing high-resolution measurements of fast-neutron energies. The best time-of-flight (3He,n) measurements report resolutions not better than 250 keV. This lack of experimental resolution has hindered a full understanding of the role of proton pairing in nuclei.

In the present work, this experimental constraint is addressed by detecting the γ-ray decay of populated excited states in an array of escape-suppressed HPGe detectors in coincidence with neutron detectors placed near θlab = 0o. High selectivity is obtained and a large rejection factor of unwanted reaction channels, of the order of 1 in 103, is demonstrated. The population strength of excited states is deduced with an energy resolution better than 3 keV. This allows the proton occupancy of excited states, populated selectively in direct two-proton stripping reactions, to be measured.

We use the 59Co(3He,n)61Cu reaction at Elab = 22.5 MeV to populate 2p-1h proton states across the Z = 28 closed shell. The observed relative L = 0 two-proton stripping strengths are compared with large-basis shell-model calculations. Discrepancies with theory suggest that proton occupancies of the f7/2 shell are not currently well reproduced. Systematic measurements in various mass regions are underway in order to address the present lack of high-resolution experimental data.

Editors-in-Chief
David Blaschke, Thomas Duguet and Maria Jose Garcia Borge
Thank you very much; that was exceptionally fast, and excellent quality. We would like to thank you for your thorough work. We understand that our papers are often quite challenging to typeset and we appreciate your professionalism and efficiency.

Harald Griesshammer, The George Washington University, Washington DC, USA

ISSN (Electronic Edition): 1434-601X

© Società Italiana di Fisica and
Springer-Verlag