87 research outputs found
Single Gate P-N Junctions in Graphene-Ferroelectric Devices
Graphene's linear dispersion relation and the attendant implications for
bipolar electronics applications have motivated a range of experimental efforts
aimed at producing p-n junctions in graphene. Here we report electrical
transport measurements of graphene p-n junctions formed via simple
modifications to a PbZrTiO substrate, combined with a
self-assembled layer of ambient environmental dopants. We show that the
substrate configuration controls the local doping region, and that the p-n
junction behavior can be controlled with a single gate. Finally, we show that
the ferroelectric substrate induces a hysteresis in the environmental doping
which can be utilized to activate and deactivate the doping, yielding an
`on-demand' p-n junction in graphene controlled by a single, universal
backgate
Population of neutron unbound states via two-proton knockout reactions
The two-proton knockout reaction 9Be(26Ne,O2p) was used to explore excited
unbound states of 23O and 24O. In 23O a state at an excitation energy of
2.79(13) MeV was observed. There was no conclusive evidence for the population
of excited states in 24O.Comment: 6 pages, 3 figures, Proc. 9th Int. Spring Seminar on Nucl. Phys.
Changing Facets of Nuclear Structure, May 20-34, 200
Generation and division of excitation energy in heavy-ion collisions studied by measuring charged-particle survival fractions
Charged-particle survival fractions of primary projectile-like fragments from the 40Ar + 197Au reaction at 450 MeV were measured by using a large array of 32 phoswich detectors operating in coincidence with a detector of projectile-like fragments. Differential survival fractions of the primary pickup and stripping reaction products indicate a dependence of the average excitation energy generated in the primary fragments on the direction of the mass transfer
Energy distributions from three-body decaying many-body resonances
We compute energy distributions of three particles emerging from decaying
many-body resonances. We reproduce the measured energy distributions from
decays of two archetypal states chosen as the lowest and
-resonances in C populated in -decays. These states are
dominated by sequential, through the Be ground state, and direct decays,
respectively. These decay mechanisms are reflected in the ``dynamic'' evolution
from small, cluster or shell-model states, to large distances, where the
coordinate or momentum space continuum wavefunctions are accurately computed.Comment: 4 pages, 4 figures. Accepted for publication in Physical Review
Letter
Exploring Neutron-Rich Oxygen Isotopes with MoNA
The Modular Neutron Array (MoNA) was used in conjunction with a large-gap
dipole magnet (Sweeper) to measure neutron-unbound states in oxygen isotopes
close to the neutron dripline. While no excited states were observed in 24O, a
resonance at 45(2) keV above the neutron separation energy was observed in 23O.Comment: 6 pages, 4 Figures, submitted to Proc. Int. Conf. on Proton Emitting
Nuclei and Related Topics, PROCON0
Population of 13Be in a Nucleon Exchange Reaction
The neutron-unbound nucleus 13Be was populated with a nucleon-exchange
reaction from a 71 MeV/u secondary 13B beam. The decay energy spectrum was
reconstructed using invariant mass spectroscopy based on 12Be fragments in
coincidence with neutrons. The data could be described with an s-wave resonance
at E = 0.73(9) MeV with a width of Gamma = 1.98(34) MeV and a d-wave resonance
at E = 2.56(13) MeV with a width of Gamma = 2.29(73) MeV. The observed spectral
shape is consistent with previous one-proton removal reaction measurements from
14B.Comment: Published in Phys. Rev.
Structure and Decay Correlations of Two-Neutron Systems Beyond the Dripline
The two-neutron unbound systems of 16Be, 13Li, 10He, and 26O have been measured using the Modular Neutron Array (MoNA) and 4 Tm Sweeper magnet setup. The correlations of the 3-body decay for the 16Be and 13Li were extracted and demonstrated a strong correlated enhancement between the two neutrons. The measurement of the 10He ground state resonance from a 14Be(−2p2n) reaction provided insight into previous predictions that wavefunction of the entrance channel, projectile, can influence the observed decay energy spectrum for the unbound system. Lastly, the decay-in-target (DiT) technique was utilized to extract the lifetime of the 26O ground state. The measured lifetime of 4.5+1.1 −1.5 (stat.)±3(sys.) ps provides the first indication of two-neutron radioactivity
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