70 research outputs found
Enhancement in the 6He+64Zn fusion cross section at energies around the barrier: static or dynamic effect?
A new measurement of fusion cross-section for the system 4 He+64 Zn was performed at sub-barrier energy in order to cover the same energy region of previous measurements of 6 He+64 Zn. The fusion cross-section was obtained using an activation technique. From the comparison of the two excitation functions an enhancement of the fusion cross section was observed, at energy below the Coulomb barrier, in the reaction induced by 6 He in respect to the one induced by 4 He
New pathway to bypass the 15O waiting point
We propose the sequential reaction process
O(,)O as a new pathway to bypass of the
O waiting point. This exotic reaction is found to have a surprisingly
high cross section, approximately 10 times higher than the
O(,)O. These cross sections were calculated after
precise measurements of energies and widths of the proton-unbound F low
lying states, obtained using the H(O,p)O reaction. The large
cross section can be understood to arise from the more
efficient feeding of the low energy wing of the ground state resonance by the
gamma decay. The implications of the new reaction in novae explosions and X-ray
bursts are discussed.Comment: submitte
Fusion, elastic and total reaction cross sections in the collision 6 Li+ 64 Zn
The structure of the weakly bound nuclei is expected to influence the fusion mechanism at energies around and below the Coulomb barrier. Infact direct channels may be favoured with respect to fusion by the low binding energies, while Coupling of the break-up channel can be responsible for a fusion cross-section enhancement. In this context the 6Li+64Zn collision has been studied at several energies around the Coulomb barrier. The fusion cross section was measured by using an activation technique where the radioactive evaporation residues produced in the reaction were identified by the X-ray emission which follows their electron capture decay. The elastic scattering angular distributions were analyzed within the Optical Model and total reaction cross-sections were deduced from optical model calculations
Elastic scattering and heavy residue production in the collisions 6,7Li+64 Zn around the Coulomb barrier
Elastic scattering angular distributions and heavy residue production cross sections have been measured at different energies around the Coulomb barrier for the systems 6,7 Li+ 64 Zn. Optical model fits of the elastic angular distributions were performed using a renormalized double folding potential and absence of usual threshold anomaly in the optical potential was found. Excitation functions for heavy residue production have been measured using an activation technique. Comparison of the data with the results of different calculations show that complete fusion is the dominant reaction mechanism above the barrier, whereas the heavy residue yield below the barrier is mainly due to incomplete fusion and transfer
CaloCube: a novel calorimeter for high-energy cosmic rays in space
In order to extend the direct observation of high-energy cosmic rays up to
the PeV region, highly performing calorimeters with large geometrical
acceptance and high energy resolution are required. Within the constraint of
the total mass of the apparatus, crucial for a space mission, the calorimeters
must be optimized with respect to their geometrical acceptance, granularity and
absorption depth. CaloCube is a homogeneous calorimeter with cubic geometry, to
maximise the acceptance being sensitive to particles from every direction in
space; granularity is obtained by relying on small cubic scintillating crystals
as active elements. Different scintillating materials have been studied. The
crystal sizes and spacing among them have been optimized with respect to the
energy resolution. A prototype, based on CsI(Tl) cubic crystals, has been
constructed and tested with particle beams. Some results of tests with
different beams at CERN are presented.Comment: Seven pages, seven pictures. Proceedings of INSTR17 Novosibirs
Projectile structure effects in the collisions 6,7Li+64Zn around the Coulomb barrier.
We measured elastic scattering angular distributions and cross sections for heavy residue production for the systems 6,7 Li+ 64 Zn at different energies around the Coulomb barrier. The elastic scattering angular distributions have been reproduced by optical model fits using a renormalized double folding potential for the real and imaginary parts. Absence of usual threshold anomaly in the optical potential was found. The excitation functions for heavy residue production were measured using an activation technique. Comparison with different calculations suggest that complete fusion is the dominant reaction mechanism above the barrier whereas, below the Coulomb barrier, incomplete fusion and transfer dominate
Measurement of the atmospheric muon depth intensity relation with the NEMO Phase-2 tower
The results of the analysis of the data collected with the NEMO Phase-2
tower, deployed at 3500 m depth about 80 km off-shore Capo Passero (Italy), are
presented. Cherenkov photons detected with the photomultipliers tubes were used
to reconstruct the tracks of atmospheric muons. Their zenith-angle distribution
was measured and the results compared with Monte Carlo simulations. An
evaluation of the systematic effects due to uncertainties on environmental and
detector parameters is also included. The associated depth intensity relation
was evaluated and compared with previous measurements and theoretical
predictions. With the present analysis, the muon depth intensity relation has
been measured up to 13 km of water equivalent.Comment: submitted to Astroparticle Physic
Elastic scattering and direct reactions of the 1n halo 11Be nucleus on 64Zn near the barrier
6 pags., 3 figs. -- Rutherford Centennial Conference on Nuclear Physics 8–12 August 2011, Manchester, UKElastic scattering and direct reactions have been studied for the collisions induced by the three Beryllium isotopes 9,10,11Be, on a medium mass 64Zn target at energies near the Coulomb barrier. The elastic-scattering angular distribution of the 11Be halo nucleus shows a deviation from the classical Fresnel type diffraction behavior in the Coulomb-nuclear interference peak angular region. The deduced total reaction cross-sections for the 11Be collision is more than a factor of two than the ones measured in the collisions induced by 9;10Be. Moreover, for 11Be a large contribution to the total reaction cross-section due to transfer and break-up processes has been observed.Peer reviewe
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