Experimental impact-parameter-dependent probabilities for $K$ -shell vacancy production by fast heavy-ion projectiles

Journal Article · Thu Jan 01 04:00:00 EST 1976 · Physical Review, A (General Physics)

DOI:https://doi.org/10.1103/PhysRevA.13.204· OSTI ID:4076637

Randall, R. R.; Bednar, J. A.; Curnutte, B.; Cocke, C. L.

The impact-parameter dependence of the probability for production of target K x rays has been measured for oxygen projectiles on copper and for carbon and fluorine projectiles on argon at scaled velocities near 0.5. The O-on-Cu data were taken for 1.56-, 1.88-, and 2.69-MeV/amu O beams incident upon thin Cu foils. A thin Ar-gas target was used for 1.56-MeV/amu C and F beams, permitting measurements to be made for charge-pure C⁺⁴, C⁺⁶, F⁺⁹ and F⁺⁵ projectiles. Ar and Cu K x rays were observed with a Si(Li) detector and scattered projectiles with a collimated surface-barrier detector. Comparison of the shapes of the measured K-vacancy--production probability curves with predictions of the semiclassical Coulomb approximation (SCA) shows adequate agreement for the O-on-Cu system. For the higher ratio of projectile-to-target nuclear charge (Z₁/Z₂) characterizing the C-on-Ar and F-on-Ar systems, the SCA predictions are entirely inadequate in describing the observed impact-parameter dependence. In particular, they cannot account for large probabilities found at large impact parameters. Furthermore, the dependence of the shapes on the projectile charge state is found to become pronounced at larger Z₁/Z₂. Attempts to account for this behavior in terms of alternative vacancy-production processes are discussed.

• Research Organization: Kansas State University, Manhattan, Kansas 66506
• Sponsoring Organization: USDOE
• NSA Number: NSA-33-021182
• OSTI ID: 4076637
• Journal Information: Physical Review, A (General Physics), Journal Name: Physical Review, A (General Physics) Journal Issue: 1 Vol. 13; ISSN PLRAAN; ISSN 0556-2791
• Publisher: American Physical Society (APS)
• Country of Publication: United States
• Language: English

Related Subjects

74 ATOMIC AND MOLECULAR PHYSICS
COPPER-- OXYGEN IONS
IMPACT PARAMETER
IONIZATION
MEV RANGE 10-100
SEMICLASSICAL APPROXIMATION
TOTAL CROSS SECTIONS
X-RAY SPECTRA ARGON-- CARBON IONS-- FLUORINE IONS