Electronic stopping power of<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mmultiscripts><mml:mrow><mml:mi mathvariant="normal">B</mml:mi></mml:mrow><mml:mprescripts /><mml:mrow /><mml:mrow><mml:mn>10</mml:mn></mml:mrow><mml:mrow /><mml:mrow /></mml:mmultiscripts></mml:mrow></mml:math>in Si in random and 〈100〉 channeling directions

Santos, José Luiz dos; Behar, M.; Grande, P.L.; Boudinov, H.; Stoll, R.; Klatt, Ch.; Kalbitzer, S.

doi:10.1103/physrevb.55.13651

Cited by 23 publications

(16 citation statements)

References 19 publications

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“…Concerning heavier ions, dos Santos et al 7 reported channeling results for B while the Heidelberg and the Bologna groups did the same for N. 8,9 More recently, in the course of the present work, Jiang et al 10 reported results of axial channeling and random stopping powers for several medium-heavy ions in Si for a restricted energy range interval.…”

Section: Introductionmentioning

confidence: 82%

Random and channeling stopping powers of He and Li ions in Si

et al. 2002

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In this work we have measured the electronic stopping powers of 4 He and 7 Li ions for channeling and random directions in Si as a function of the incident ion energy. The channeling (͗100͘ for Li, ͗110͘ and ͗111͘for Li and He͒ and the random ͑Li only͒ measurements cover a wide energy range between 200 keV and 9 MeV. The Rutherford backscattering technique together with different multilayer targets has been employed in the present experiments. The results are compared to calculations carried out in the framework of the unitary convolution approximation, which takes into account the impact-parameter-dependent energy loss for each projectile charge state, with further refinements including screening effects in close collisions between the electrons of the target and the screened projectile.

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Section: Introductionmentioning

confidence: 82%

Random and channeling stopping powers of He and Li ions in Si

et al. 2002

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“…2 and 3. In the case of B and the ͗100͘ direction, other channeling data measured by Jiang et al [15] and dos Santos et al [14] are displayed as well. The quoted errors have been estimated from several measurements.…”

Section: Resultsmentioning

confidence: 99%

“…[15]. Open triangles: channeling data by dos Santos et al [14]. The Barkas-polarization enhancement is given by the difference in the dE / dx value between the squares and solid line.…”

Section: Resultsmentioning

confidence: 99%

“…Therefore, we have embarked on measurements of the channeling stopping power of 11 B and 9 Be in Si ͗100͘ and ͗110͘ directions as a function of the ion energy. While 11 B has been measured along the Si ͗100͘ previously [14,15], this is the first measurement of 9 Be under channeling conditions in Si. The the-PHYSICAL REVIEW A 70, 032903 (2004) oretical background used to interpret the data relies on a binary collision approximation combining self-consistent nonlinear calculations based on the transport cross-section approach [16] with the unitary convolution approximation to describe the impact-parameter dependence of the energy loss [17].…”

Section: Introductionmentioning

confidence: 99%

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Electronic energy loss of channeled ions: The giant Barkas effect

et al. 2004

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In this work we have measured the electronic energy loss of 9 Be and 11 B ions for the ͗100͘ and ͗110͘ directions in Si as a function of the incident ion energy. The channeling measurements cover a wide energy range between 100 keV/ amu and 1 MeV/ amu. The Rutherford backscattering technique has been employed in the present experiments. An overall compilation of channeling energy loss values for several ions, including those for He, Li, and O measured previously, provides a clear picture of the Barkas contribution to the stopping power due to valence electrons in the present energy regime. A maximum of the relative contribution occurs for Be ions around 250 keV/ amu while a saturation effect is observed for heavier ions. These results are interpreted in terms of a self-consistent nonlinear calculation based on the transport cross-section approach together with the unitary convolution approximation model, which describe the present data reasonably well at high projectile energies.

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“…The error bars represent statistical uncertainties. Part of the data for the ͗100͘ direction were published previously [19,20]. The UCA results without (solid lines) and with the Barkas correction by Lindhard (dashed lines) are shown for comparison.…”

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Giant Barkas Effect Observed for Light Ions Channeling in Si

et al. 2001

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Measurements of the electronic energy loss are presented for 4 He and 7 Li ions channeling along the Si main axial directions at intermediate to high projectile energies. The Barkas effect, an energy-loss enhancement proportional to the third power of the projectile charge at high energies, is clearly separated from other processes. It reaches about 50% for Li ions channeling along the Si ͗110͘ direction. The observed Barkas contribution from the valence-electron gas is in fair agreement with the Lindhard model. DOI: 10.1103/PhysRevLett.86.1482 The energy loss of ions slowing down in matter has been investigated for many years because of its relevance for ion beam analysis, materials modification, and nuclear physics. Moreover, there exist fundamental issues concerning the underlying physical processes of the energy loss at low and intermediate projectile energies. At high velocities, the main energy-loss mechanisms (ionization and excitation) are qualitatively well understood. But important points related to energy loss in the polarization field are still unclear. For the weakly interacting fast light ions, the polarization field is given by the dielectric function of the medium. It corresponds to an enhanced electron density around positive ions and to a reduction around negatively charged particles. This effect yields a Z 3 contribution to the stopping power at high velocities (Z is the projectile charge), and thus, it depends on the sign of the projectile charge.This so-called Barkas effect has first been observed by Barkas and collaborators [1] who found that the range of negative pions exceeds the one of positive pions with equal incident velocity. A direct determination of a relatively small Barkas effect has recently been performed using antiprotons and protons [2,3]. For heavier projectiles, other higher-order effects as well as shell corrections compete equally with the Barkas effect, and thus a clear and unequivocal separation of this effect from the others has not been achieved successfully yet [4]. Previously, channeling measurements of the Barkas effect [5,6] were performed under conditions where the so-called Bloch correction [7] is of comparable magnitude but of opposite sign as the Barkas contribution. The leading term of the Bloch correction is proportional to Z 4 , and it is closely related to the restriction of reaction probabilities to a maximum of 1 per target electron. To overcome these problems, it is therefore essential to determine the magnitude of the Barkas effect in an alternative way, where sources of errors are minimized.All theoretical models of the Barkas effect (reviewed by Basbas [8]) agree about the importance of the polarization of the medium in distant collisions, where ions act similar to photons. However, the importance of close collisions has been a subject of controversy in the literature [8]. Lindhard [9] stated that the close collisions may contribute nearly equally to the Barkas effect, because of the influence of the dynamical screening potential on electron-scatteri...

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Electronic stopping power ofB10in Si in random and 〈100〉 channeling directions

Cited by 23 publications

References 19 publications

Random and channeling stopping powers of He and Li ions in Si

Random and channeling stopping powers of He and Li ions in Si

Electronic energy loss of channeled ions: The giant Barkas effect

Giant Barkas Effect Observed for Light Ions Channeling in Si

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