Skip to main content
OSTI.GOVU.S. Department of Energy Office of Scientific and Technical Information
U.S. Department of Energy
Office of Scientific and Technical Information
 

Accurate evaluation of stopping and straggling mean excitation energies for N, O, H/sub 2/, N/sub 2/, O/sub 2/, NO, NH/sub 3/, H/sub 2/O, and N/sub 2/O using dipole oscillator strength distributions. A test of the validity of Bragg's rule

Journal Article · · Radiat. Res.; (United States)
DOI:https://doi.org/10.2307/3574587· OSTI ID:7323281
 [1]; ; ;
  1. Univ. of Western Ontario, London
+ Show Author Affiliations

Accurate values of the mean excitation energy I/sub 0/ (occurring in the Bethe stopping cross section equation for fast charged particles) and the dipole oscillator strength sum S/sub 1/ and mean excitation energy I/sub 1/ (appearing in the equation for straggling given by Fano) have been determined for N, O, H/sub 2/, O/sub 2/, O/sub 2/, NH/sub 3/, H/sub 2/O, NO, and N/sub 2/O using dipole oscillator strength distributions. For energies for which the Bethe stopping theory is valid these results allow a quantitative test to be made of the reliability of Bragg's rule and of the analogous additivity rule for straggling. Difficulties arising from problems associated with the use of experimental stopping cross sections and the treatment of shell corrections, that have introduced uncertainty in previous studies of Bragg's rule, are avoided in the present work. Using the accurate results obtained for H/sub 2/, N/sub 2/, and O/sub 2/ as elemental values in the additivity relations, the additivity estimates of S/sub 1/, I/sub 1/, and I/sub 0/ obtained for N, O, NH/sub 3/, H/sub 2/O, NO, and N/sub 2/O agree with the accurate results to within 0.4, 0.9, and 4%, respectively. On the other hand, for the H atom large discrepancies (20--30%) between the accurate values for S/sub 1/, I/sub 1/, and I/sub 0/ and the estimates obtained by additivity occur and are due to major modifications in the electronic wavefunction in regions close to the proton that are caused by chemical binding. For heavier atoms this effect is relatively unimportant. For H/sub 2/, N/sub 2/, and O/sub 2/ calculated Bethe stopping cross sections are compared with experimental results and are used to discuss shell corrections to the Bethe stopping cross section equation.

OSTI ID:
7323281
Journal Information:
Radiat. Res.; (United States), Journal Name: Radiat. Res.; (United States) Vol. 70:2; ISSN RAREA
Country of Publication:
United States
Language:
English

Similar Records

Stopping cross sections for helium and hydrogen in H$sub 2$, N$sub 2$, O$sub 2$, and H$sub 2$S (0.3 to 2.5 MeV)
Journal Article · Fri Oct 31 23:00:00 EST 1975 · Phys. Rev., B, v. 12, no. 9, pp. 3575-3583 · OSTI ID:4121208
Dipole Spectrum of Water Vapor and Its Relation to the Energy Loss of Fast-Charged Particles
Journal Article · Tue Jul 01 00:00:00 EDT 1975 · Radiation Research · OSTI ID:4138045
Stopping and straggling mean excitation energies, related properties, and their additivity, for the normal alkanes
Journal Article · Sat Oct 01 00:00:00 EDT 1983 · Radiat. Res.; (United States) · OSTI ID:5580951

Related Subjects

654001* -- Radiation & Shielding Physics-- Radiation Physics
Shielding Calculations & Experiments
73 NUCLEAR PHYSICS AND RADIATION PHYSICS
ABSORPTION
ALPHA PARTICLES
AMMONIA
BARYONS
CHALCOGENIDES
CHARGED PARTICLES
CHARGED-PARTICLE TRANSPORT
CORRECTIONS
CROSS SECTIONS
CRYOGENIC FLUIDS
DISTRIBUTION
ELEMENTARY PARTICLES
ELEMENTS
ENERGY-LEVEL TRANSITIONS
EXCITATION
FERMIONS
FLUIDS
HADRONS
HYDRIDES
HYDROGEN
HYDROGEN COMPOUNDS
NITRIC OXIDE
NITROGEN
NITROGEN COMPOUNDS
NITROGEN HYDRIDES
NITROGEN OXIDES
NITROUS OXIDE
NONMETALS
NUCLEONS
OSCILLATOR STRENGTHS
OXIDES
OXYGEN
OXYGEN COMPOUNDS
PROTONS
RADIATION TRANSPORT
SLOWING-DOWN
WATER