The Dielectric Formalism for Inelastic Processes in High-Energy Ion–Matter Collisions

2017

Phys. Rev. A

In this work we propose a non-perturbative approximation to the electronic stopping power based on the central screened potential of a projectile moving in a free electron gas, by Nagy and Apagyi [Phys. Rev. A 58 (1998. We used this model to evaluate the energy loss of protons and antiprotons in ten solid targets: Cr, C, Ni, Be, Ti, Si, Al, Ge, Pb, Li and Rb. They were chosen as canonicals because they have reliable Wigner-Seitz radius, rs=1.48 to 5.31, which cover most of the possible metallic solids. Present low velocity results agree well with the experimental data for both proton and antiproton impact. Our formalism describes the binary collision of the projectile and one electron of the free electron gas. It does not include the collective or plasmon excitations, which are important in the intermediate and high velocity regime. The distinguishing feature of this contribution is that by using the present model for low to intermediate energies and the Lindhard dielectric formalism for intermediate to high energies, we describe the stopping due to the free electron gas in an extensive energy range. Moreover, by adding the inner-shell contribution using the shellwise local plasma approximation, we were able to describe all the available experimental data in the low, intermediate and high energy regions.

Section: Comparison With the Experiments In An Extended Energy Rangementioning

confidence: 99%

Section: Comparison With the Experiments In An Extended Energy Rangementioning

confidence: 99%

See 1 more Smart Citation

Low- and intermediate-energy stopping power of protons and antiprotons in solid targets

2017

Phys. Rev. A

“…An analytical expression of the screened projectile charge Z P (Z N ,N e ,r) as a function of the distance to the nucleus r, the nuclear charge Z N and number of bound electrons N e , can be found in [29]. A tabulation of Z P (Z N ,N e ,r) for ions He up to Ne is included in [73].…”

Section: Straggling In Solidsmentioning

confidence: 99%

The energy loss straggling of low Z ions in solids and gases

AIP Conference Proceedings

2013

We present a study on the energy loss straggling of low Z ions (H up to B) in different solid (Al, Ti, Cu, Zn, Ge, Au) and gaseous targets (Ne, Ar, Kr, Xe). This work includes on one side, a critical analysis of the available experimental data and possible non-statistical (rugosity and inhomogeneity) contributions. On the other side, theoretical calculations performed by using the shell-wise local plasma approximation and the comparison of these results with the experimental data and with other theoretical curves available in the literature. We find that for the ions here considered, the square of the energy loss straggling normalized to Bohr limit is independent of the ion nuclear charge and of the ion charge state, in the case of electrons bound to the projectile. This shows a clear Z 2 dependence of the square energy loss straggling, with Z being the ion nuclear charge. The tendency to Bohr limit at high energies, and the inconvenience of using Yang formula (Q. Yang etal, Nucl. Instrum. Meth. Phys. Res B 61, 149-155 (1991)) are also mentioned. The bases for the future development of a general formula for the energy loss straggling are introduced.

“…These are binary collisional formalisms within the independent electron model. On the other hand, the dielectric formalism is employed by using the shell-wise local plasma approximation (SLPA) [55]. The SLPA describes the response of the electrons of the same binding energy as a whole (collectively, including all the electron interactions), screening the interaction with the impinging ion.…”

Section: Introductionmentioning

confidence: 99%

Neonization method for stopping, mean excitation energy, straggling, and for total and differential ionization cross sections of CH₄, NH₃, H₂O and FH by impact of heavy projectiles

J. Phys. B: At. Mol. Opt. Phys.

2013

We propose a neonization method to deal with molecules composed by hydrides of the second row of the periodic table of elements: CH 4 , NH 3 , OH 2 and FH. This method describes these ten-electron molecules as dressed atoms in a pseudo-spherical potential. We test it by covering most of the inelastic collisional magnitudes of experimental interest: ionization cross sections (total, single and double differential), stopping power, energy-loss straggling and mean excitation energy. To this end, the neonization method has been treated with different collisional formalisms, such as the continuum-distorted-wave-eikonal-initial-state, the first order Born, and the shell-wise local plasma approximations. We show that the present model reproduces the different empirical values with high reliability in the intermediate to high-energy region. We also include the expansion of the spherical wave functions in terms of Slater-type orbitals and the analytic expression for the spherical potentials. This makes it possible in the future to tackle present neonization strategy with other collisional models.