Energy Spectra Of Light Particles Research Articles

Study on reaction mechanism by analysis of kinetic energy spectra of light particles and formation of final products

The sensitivity of reaction mechanism in the formation of compound nucleus (CN) by the analysis of kinetic energy spectra of light particles and of reaction products are shown. The dependence of the PCN fusion probability of reactants and Wsur survival probability of CN against fission at its deexcitation on the mass and charge symmetries in the entrance channel of heavy-ion collisions, as well as on the neutron numbers is discussed. The possibility of conducting a complex program of investigations of the complete fusion by reliable ways depends on the detailed and refined methods of experimental and theoretical analyses.

Status and perspectives of fragmentation beams at LNS with CHIMERA detector

Relatively large yields of various exotic beams produced through in-flight fragmentation are available at LNS. Using the CHIMERA detector, we performed various experiments to study elastic and inelastic scattering, transfer, break-up, and reaction dynamics with targets from proton and deuteron to carbon and heavier. For reactions with relatively light systems we used the kinematical coincidence method to extract high resolution angular distributions of binary reactions from the measured light particle energy spectra. We also used the CsI detectors of CHIMERA to detect gamma rays emitted in the reactions. Some of most recent results are presented together with future perspectives with the coupling of CHIMERA with FARCOS array.

Transfer reactions on light exotic nuclei studied with CHIMERA detector at LNS

The kinematical coincidence method is used to extract angular distribution of elastic scattering and transfer reactions. The detected light particle energy spectra are used to extract the angular distribution with around 1° resolution in the Center of Mass (CM) system. Examples with 10 Be beam are presented. In the case of proton scattering, γ -ray coincidences are used to discriminate excited levels population from elastic scattering.

Validation of nuclear reaction models of 180 MeV proton-induced fragmentation of 27Al

Kinetic energy, angular distribution, and isobaric cross section data for A = 7–25 fragments formed in p + 27Al reaction at bombarding energy of 180 MeV are compared with the calculations of the Binary Cascade Model (BIC), the Cascade Exciton Model (CEM), JQMD/PHITS, as well as the Statistical Model with Final State Interaction (SMFSI). For completeness, the kinetic energy spectra of light particles (n, p, α) formed in p + 27Al reaction at bombarding energy of 156 MeV are also presented. A general agreement between the data and predictions of these models is found. However, disagreement with the data for the yields of light-mass fragments as well as near-target fragments is also found and discussed. The importance of this comparative study to simulation and analysis of radiation effects on microscopic electrical components operating in space is also discussed.

The role of isospin in fusion evaporation reactions

The isospin dependence of the level density, both through the level density parameter and the symmetry energy contribution has been evaluated. The effects on the most relevant observables in fusion evaporation reactions have been estimated by using the statistical model. We present here the results for the 134Sn +4 He reaction, whose measurement will be possible with the second generation RIB facilities SPES and SPIRAL2. Sizeable effects are predicted on the light particle energy spectra and multiplicities and evaporation residue distribution. In particular, the measure of evaporation residue yields and light particle multiplicities are expected to unfold the two effects. In addition, the same calculations have been carried out for reactions induced by stable beams, in order to search for clues of isospin effects. In this case, the direct comparison of the experimental light charged particle energy spectra for the two reactions 7Li+58,64Ni at the same excitation energy and angular momentum, is proposed as a good approach to observe isospin effects.

Multiplicity dependence of intermediate-energy 12C, 18O and 20Ne induced reactions

Energy spectra of light particles emitted in the interaction of 84 MeV· A 18O and 48 MeV· A 20Ne ions with different targets have been measured with telescopes consisting of NaI, BGO and surface-barrier detector stacks. The inclusive data have been analysed within a moving-source parametrization. By using a large-area plastic-scintillator detector arrangement covering the target with a solid angle of about 2π, light-charged-particle multiplicity distributions have been measured and multiplicity-selected light-particle spectra have been obtained. It is shown that multiplicity selection allows a rough separation of peripheral and central processes and will be a suitable means for probing different theoretical models of nucleon emission.

Particle emission in the light heavy-ion fusion reactions: 14N, 16,18O+ 12C.

From the energy spectra of light particles produced in light-heavy-ion-induced reactions, level densities of the final nuclei as well as the critical angular momenta for fusion may be obtained. The /sup 14/N, /sup 16,18/O+ /sup 12/C reactions were investigated in the energy range 30 MeV

Momentum widths in the fragmentation of 32 MeV/uB10

Momentum widths of fragments produced in the reactions of 320 MeV /sup 10/B with /sup 181/Ta have been measured. At forward angles the energy spectra of light particles (Z = 1,2) exhibit energy peaks characterized by a reduced momentum with sigma/sub 0/ = 54 MeV/c, which is well below the values near 85 MeV/c observed in the reactions of 43 MeV/u /sup 20/Ne with /sup 181/Ta and in reactions induced by relativistic heavy ions. These results suggest a rapid increase in momentum widths, or apparent temperature, in the 32 to 43 MeV/u range.

Trends of light particle spectra observed in nucleus-nucleus collisions

The emission of energetic light particles (p,d,t) has been studied for 16O induced reactions on Al, Zr and Au targets at the incident energies of 140, 215 and 310 MeV. The light-particle energy spectra have been analyzed in terms of a moving thermal source. The apparent temperatures exhibit a systematic variation as a function of the incident energy per nucleon above the Coulomb barrier. The observed trend can be extrapolated in a smooth fashion to temperatures obtained in relativistic heavy-ion collisions.

Coalescence of Light Particles in the ReactionO16+U238at 315 MeV

The energy spectra of light particles ($p$,$d$,$t$) produced in $^{16}\mathrm{O}$-induced reactions on $^{238}\mathrm{U}$ at 315 MeV can be rather well described by thermal distributions in a rest frame that moves with about half the beam velocity. The energy spectra of deuterons and tritons can be related to the proton energy spectra by a coalescence model that incorporates Coulomb effects.

Coalescence of Light Particles in the ReactionO16+U238at 315 MeV

The energy spectra of light particles ($p$,$d$,$t$) produced in $^{16}\mathrm{O}$-induced reactions on $^{238}\mathrm{U}$ at 315 MeV can be rather well described by thermal distributions in a rest frame that moves with about half the beam velocity. The energy spectra of deuterons and tritons can be related to the proton energy spectra by a coalescence model that incorporates Coulomb effects.

Light Charged Particles and Fission Elements from Californium-252 Fission

Light charged particles (LCP) and fission elements formed in ternary fission of /sup 252/Cf have been investigated. The energy spectra of light particles, alphas, and protons were studied using a ..delta.. E X (E + ..delta.. E) particle-identifying telescope apparatus. A coincidence circuit was used in such a way that the K x rays from the ternary fission fragments were electronically gated by a designated LCP and then stored in a multichannel analyzer. The K x rays were analyzed using a high-resolution lithium-drifted silicon spectrometer, permitting accurate identification of the elements in the charge distribution of fission fragments. Experimental results indicate the influence of the odd-even effect and also of shape deformation of alpha-accompanied ternary fission.