Mean excitation energy for the stopping power of light elements.
We have evaluated the mean excitation energy or I value for Coulomb excitations by swift charged particles passing through carbon, aluminum and silicon. A self-consistent Kramers-Kronig analysis was used to treat X-ray optical spectra now available from synchrotron light sources allowing us to carry out Bethe's original program of evaluating I from the observed dielectric response. We find that the K and L shell are the dominant contributors to I in these light elements and that the contribution of valence electrons is relatively small, primarily because of their low binding energy. The optical data indicate that Si and Al have nearly equal I values, in contrast to Bloch's Thomas-Fermi result, I {infinity} Z. The optically based I values for C and Al are in excellent agreement with experiment. However, the dielectric-response I value for Si is 164 {+-} 2 eV, at variance with the commonly quoted value of 173 {+-} 3 eV derived from stopping-power measurements.
- Research Organization:
- Argonne National Lab. (ANL), Argonne, IL (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC); National Science Foundation (NSF)
- DOE Contract Number:
- DE-AC02-06CH11357
- OSTI ID:
- 947966
- Report Number(s):
- ANL/PHY/CP-117490; TRN: US0901480
- Journal Information:
- Nucl. Instrum. Methods Res. B, Vol. 250, Issue 2006; Conference: 13th International Conference on Radiation Effects in Insulators (REI-2005); Aug. 28, 2005 - Sep. 2, 2005; Santa Fe, NM
- Country of Publication:
- United States
- Language:
- ENGLISH
Similar Records
Mean excitation energy for the stopping power of metallic aluminum: Comments on an article by McGuire
A linear, separable two-parameter model for dual energy CT imaging of proton stopping power computation