The reactions induced by the weakly bound
6Li projectile interacting with the intermediate mass target
59Co were investigated. Light charged particles singles and
α–
d coincidence measurements were ...performed at the near barrier energies
E
lab
=
17.4
, 21.5, 25.5 and 29.6 MeV. The main contributions of the different competing mechanisms are discussed. A statistical model analysis, Continuum-Discretized Coupled-Channels (CDCC) calculations and two-body kinematics were used as tools to provide information to disentangle the main components of these mechanisms. A significant contribution of the direct breakup was observed through the difference between the experimental sequential breakup cross section and the CDCC prediction for the non-capture breakup cross section.
.
In the framework of the experimental campaign of the (
p
,
α
) and (
n
,
α
) reactions cross sections measurement involving the
10, 11
B isotopes, different (
n
,
α
) cross section measurements ...have been performed at ultra-low energy. In this work, the
10
B(
n
,
α
)
7
Li reaction was investigated through the Trojan Horse Method, by means of the Quasi-Free (QF)
2
H(
10
B,
α
7
Li)
1
H reaction at 30 MeV of beam energy. As in the standard THM approach, the measurement has been performed in inverse kinematics using a
10
B beam. The excitation function of the
10
B(
n
,
α
)
7
Li reaction has been measured at a center-of-mass energy between 0 and 700 keV. The data were compared with the existing experimental ones. Even if the energy resolution of the present experiment did not allow a separation between the channels (
n
,
α
0
) and (
n
,
α
1
) the low energy cross section and the angular distribution are presented, pointing out once more the ability of the method in studying neutron induced reactions using deuteron as source of virtual neutrons.
An experimental overview of reactions induced by the stable, but weakly-bound nuclei
6Li,
7Li and
9Be, and by the exotic, halo nuclei
6He,
8B,
11Be and
17F on medium-mass targets, such as
58Ni,
59Co ...or
64Zn, is presented. Existing data on elastic scattering, total reaction cross sections, fusion processes, breakup and transfer channels are discussed in the framework of a CDCC approach taking into account the breakup degree of freedom.
The accurate knowledge of thermonuclear reaction rates is important in understanding the energy generation, the neutrinos luminosity and the synthesis of elements in stars. The physical conditions ...under which the majority of astrophysical reactions proceed in stellar environments make it difficult or impossible to measure them under the same conditions in the laboratory. That is why different indirect techniques are being used along with direct measurements. The Trojan Horse Method (THM) is introduced as an independent technique to obtain the bare nucleus astrophysical S(E)-factor. As examples the results of recent the application of THM to the 2H(11B, σ08Be)n and 2H(10B, σ07Be)n reactions are presented.
A review of the characteristic features found in fully energy-damped, binary decay yields from light heavy-ion reactions with 20≤
A
target+
A
projectile≤80 is presented. The different aspects of ...these yields that have been used to support models of compound-nucleus (CN) fission and deep-inelastic dinucleus orbiting are highlighted. Cross-section calculations based on the statistical phase space at different stages of the reaction are presented and compared to the experimental results. Although the statistical models are found to reproduce most of the observed experimental behaviors, an additional reaction component corresponding to a heavy-ion resonance or orbiting mechanism is also evident in certain systems. The system dependence of this second component is discussed. The extent to which the binary yields in very light systems (
A
CN≤32) can be viewed as resulting from a fusion–fission mechanism is explored. A number of unresolved questions, such as whether the different observed behaviors reflect characteristically different reaction times, are discussed.
We present a method to determine the magnitude of the uncorrelated background distribution obtained with the event mixing technique, through the simultaneous observation of the projectile elastic ...scattering in different detectors, which correspond to random coincidences. The procedure is tested with
α
–
d
angular correlation data from the
Li
6
+
Co
59
reaction at
E
lab
=
29.6
MeV
. We also show that the method can be applied using the product of singles events, when singles measurements are available.
6Li direct breakup lifetimes Souza, F.A.; Carlin, N.; Beck, C. ...
Nuclear physics. A,
03/2010, Volume:
834, Issue:
1
Journal Article
Peer reviewed
Open access
α
−
d
coincidence data are studied for the
6Li +
59Co reaction at
E
l
a
b
=
29.6
MeV
. A kinematic analysis is used to identify which process, leading to the same final state, has the major ...contribution for selected angular regions. The contributions of the
6Li sequential and direct breakup to the incomplete fusion/transfer process is discussed by considering the corresponding lifetimes obtained by using a semiclassical approach.
High-energy nuclear collisions create an energy density similar to that of the Universe microseconds after the Big Bang; in both cases, matter and antimatter are formed with comparable abundance. ...However, the relatively short-lived expansion in nuclear collisions allows antimatter to decouple quickly from matter, and avoid annihilation. Thus, a high-energy accelerator of heavy nuclei provides an efficient means of producing and studying antimatter. The antimatter helium-4 nucleus (4He), also known as the anti-α (α), consists of two antiprotons and two antineutrons (baryon number B = -4). It has not been observed previously, although the α-particle was identified a century ago by Rutherford and is present in cosmic radiation at the ten per cent level. Antimatter nuclei with B < -1 have been observed only as rare products of interactions at particle accelerators, where the rate of antinucleus production in high-energy collisions decreases by a factor of about 1,000 with each additional antinucleon. Here we report the observation of 4He, the heaviest observed antinucleus to date. In total, 18 4He counts were detected at the STAR experiment at the Relativistic Heavy Ion Collider (RHIC; ref. 6) in 10(9) recorded gold-on-gold (Au+Au) collisions at centre-of-mass energies of 200 GeV and 62 GeV per nucleon-nucleon pair. The yield is consistent with expectations from thermodynamic and coalescent nucleosynthesis models, providing an indication of the production rate of even heavier antimatter nuclei and a benchmark for possible future observations of 4He in cosmic radiation.
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