179 research outputs found
Prompt dipole radiation in fusion reactions
The prompt gamma ray emission was investigated in the 16A MeV energy region
by means of the 36,40Ar+96,92Zr fusion reactions leading to a compound nucleus
in the vicinity of 132Ce. We show that the prompt radiation, which appears to
be still effective at such a high beam energy, has an angular distribution
pattern consistent with a dipole oscillation along the symmetry axis of the
dinuclear system. The data are compared with calculations based on a collective
bremsstrahlung analysis of the reaction dynamics
PRISMA - a magnetic spectrometer for heavy ions at LNL
Abstract The heavy-ion magnetic spectrometer PRISMA was recently installed at Laboratori Naz. di Legnaro, in order to exploit the heavy-ion beams of the XTU Tandem-ALPI-PIAVE accelerator complex, with masses up to A≃200 at energies ≃5-10 MeV MeV A
Cambiamenti nel regime pluviometrico in ecosistemi mediterranei: il progetto MIND
Changes in rainfall patterns in Mediterranean ecosystems: the MIND project. Will Mediterranean terrestrial ecosystems be affected by the expected changes in precipitation regimes? If so, by how much and in which direction? These questions are at the basis of the research performed in context of the EU MIND project, whose key objectives were: i) to investigate the potential effects of increasing drought on Mediterranean terrestrial ecosystems at the process, ecosystem and regional scales and ii) to assess ecosystem vulnerability to changes in rainfall patterns. A network of experimental study sites has been created in Portugal, Spain, France and Italy, where field manipulations alter the amount of water available to the ecosystem. The most up-to-date methods of ecophysiology, micrometeorology, soil ecology and remote sensing have been used to elucidate the mechanisms that regulate the response of vegetation and soil to changes in water availability. This information is providing the basis for the implementation and validation of simulation models capable of predicting the drought response of Mediterranean terrestrial ecosystems, and their vulnerability to future climate change, on a larger scale. The out-coming results are elucidating how water availability affects plant ecophysiological processes, the dynamics of soil carbon and the overall exchange of mass and energy between the land and the atmosphere. This paper focuses on some of the important, yet preliminary, results on C and energy fluxes that have been obtained at the large scale troughfall manipulation experiment (Tolfa, Italy), in a forest dominated by Arbutus unedo L
Evidence of dynamical dipole excitation in the fusion-evaporation of the 40Ca +152Sm heavy system
The excitation of the dynamical dipole mode along the fusion path was investigated for the first time
in the formation of a heavy compound nucleus in the
A
∼
190 mass region. The compound nucleus was
formed at identical conditions of excitation energy and spin from two entrance channels: the charge-asymmetric
40
Ca
+
152
Sm and the nearly charge-symmetric
48
Ca
+
144
Sm at
E
lab
=
11 and 10.1 MeV
/
nucleon, respectively.
High-energy
γ
rays and light charged particles were measured in coincidence with evaporation residues by
means of the MEDEA multidetector array (Laboratori Nazionali del Sud, Italy) coupled to four parallel plate
avalanche counters. The charged particle multiplicity spectra and angular distributions were used to pin down
the average excitation energy, the average mass, and the average charge of the compound nucleus. The
γ
-ray
multiplicity spectrum and angular distribution related to the nearly charge-symmetric channel were employed to
obtain new data on the giant dipole resonance in the compound nucleus. The dynamical dipole mode excitation in
the charge-asymmetric channel was evidenced, in a model-independent way, by comparing the
γ
-ray multiplicity
spectra and angular distributions of the two entrance channels with each other. Calculations of the dynamical
dipole mode in the
40
Ca
+
152
Sm channel, based on a collective bremsstrahlung analysis of the reaction dynamics,
are presented. Possible interesting implications in the superheavy-element quest are discussed
The Magnetic Spectrometer Prisma at Lnl
The magnetic spectrometer PRISMA [1,2,3] has been recently installed at LNL. It has been designed to be used with heavy-ion beams accelerated at energies up to E = 5-10 AMeV by means of the Tandem-ALPI accelerator complex of the Laboratori Nazionali di Legnaro. The next operation of the new superconductive injector PIAVE and its coupling with the ALPI Linac will allow to extend the nuclear physics studies in the A=100-200 mass region. Moreover, PRISMA i
Does the breakup process affect the reaction dynamics for the systems 17O, 17F + 58Ni at Coulomb barrier energies?
The scattering processes of two mirror projectiles, the well bound 17 O (Sn = 4.143 MeV) and the loosely bound radioactive 17 F (Sp = 0.600 MeV), on the proton closed shell target 58 Ni were measured at several energies around the Coulomb barrier. The experimental data were analyzed within the framework of the optical model to extract the reaction cross section and to investigate the role played by direct reaction channels at near-barrier energies. The comparison shows a similar behaviour for the two A = 17 projectiles despite their very different binding energies and suggests a rather small effect of the 17 F breakup channel on the reaction dynamics
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Effective temperatures in complete fusion for the system {sup 58}Ni + {sup 58}Ni at 500 MeV bombarding energy
Triple coincidences between complex fragments with Z > 3, light charged particles and {gamma} transitions have been measured for the system {sup 58}Ni+{sup 58}Ni at 500 MeV incident energy. To this end the HILI detector and a 19 pack BaF{sub 2} cluster made of 19 crystals of TAPS geometry have been used. Effective temperatures have been obtained from the ratios of the bound excited level cross sections to the ground states ones for C. N and 0 evaporated after complete fusion of {sup 58}Ni +{sup 58}Ni at 500 MeV incident energy. The dependence of the effective temperature on the charged light particle multiplicity has been investigated
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