2018 Impact factor 1.660
Special Topics

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.

Managing Editors
Anne Ruimy (EDP Sciences) and Sabine Lehr (Springer-Verlag)
Dear Isabelle, dear Ms. Lehr,
We want to express our sincere thanks to you for your outstanding work perfectly in time.

Kerstin Eckert, TU Dresden, Germany
on behalf of the other Editors EPJ Special Topics 220, 2013

ISSN: 1951-6355 (Print Edition)
ISSN: 1951-6401 (Electronic Edition)

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