Speaker
Giacomo Randisi
(LPC Caen)
Description
The unbound systems 10,12 Li and 13Be have been studied via nucleon removal from a 14B
beam of 35 MeV/nucleon. The invariant mass spectra were reconstructed from
the measured 9,11Li-n and 12Be-n coincidences. Simulations, taking into account the effects of
the experimental setup and the reaction, were developed. The reconstructed decay energy spectra
and momentum distributions were interpreted using theoretical lineshapes folded
with the experimental response, as well as uncorrelated distributions obtained from the data by event mixing.
In the case of 10Li, the data were reproduced with an s-wave virtual state of scattering length
as = −10 +-3 (stat) +-3 (syst) fm, combined with an l = 1 resonance of energy Er = 0.55 +- 0.02 (stat) +- 3
0.05 (syst) MeV and a width of 0.35 ± 0.05 (stat) ± 0.15 (syst) MeV. This result confirms the 1p1/2 -2s1/2
inversion.
For 12Li, evidence was found for excited states with an energy between 0.2 and 0.8 MeV
above the threshold.
In the case of 13Be, the decay energy, as well as the other observables, were
reproduced assuming an l = 0 resonance at 0.7+-0.05 (stat) +- 0.07 (syst) MeV
and a width of 1.7 +- 0.1 (stat) +- 0.1 (syst) MeV, combined with an l = 2 resonance with energy
Er = 2.4 +- 0.1 (stat) +- 0.1 (syst) MeV and a width of 0.6 +- 0.2 (stat) +- 0.1 (syst) MeV.
This hypothesis is supported by the selectivity of proton knockout, whereby the neutron configuration
of the states populated in 13Be should directly reflect that of 14B.
Primary author
Giacomo Randisi
(LPC Caen)
