Observations of resonance-like structures for positron-atom scattering at intermediate energies

Thesis/Dissertation · Fri Jan 01 04:00:00 EST 1993

OSTI ID:7003949

Dou, L

Absolute values of elastic differential cross sections (DCS's) are measured for position (e[sup +]) scattering by argon (8.7-300 eV) krypton (6.7-400 eV) and also neon (13.6-400 eV) using a crossed-beam experimental setup. When the DCS's are plotted at fixed scattering angles of 30[degrees], 60[degrees], 90[degrees] and 120[degrees] versus energy it has been found that well-defined resonance-like structures are found at an energy of 55-60 eV for argon and at 25 and 200 eV for krypton, with a broader structure found between 100-200 eV for neon. These observed resonance-like structures are unusual because they occur at energies well above the known inelastic thresholds for these atoms. They may represent examples of [open quotes]coupled channel shape resonances[close quotes], first predicted by Higgins and Burke [1] for e[sup +]-H scattering in the vicinity of 36 eV (width [approx] 4 eV), which occurs only when both the elastic and positronium formation scattering channels are considered together. A more recent e[sup +]-H calculation by Hewitt et al. [2] supports the Higgins and Burke prediction. These predictions and the present observations suggest the existence of a new type of atomic scattering resonance.

• Research Organization: Wayne State Univ., Detroit, MI (United States)
• OSTI ID: 7003949
• Country of Publication: United States
• Language: English

Related Subjects

664300* -- Atomic & Molecular Physics-- Collision Phenomena-- (1992-)
74 ATOMIC AND MOLECULAR PHYSICS
ANTILEPTONS
ANTIMATTER
ANTIPARTICLES
ARGON
ATOM COLLISIONS
BEAMS
COLLIDING BEAMS
COLLISIONS
CROSS SECTIONS
DIFFERENTIAL CROSS SECTIONS
ELASTIC SCATTERING
ELEMENTARY PARTICLES
ELEMENTS
FERMIONS
FLUIDS
GASES
KRYPTON
LEPTONS
MATTER
NEON
NONMETALS
POSITRON COLLISIONS
POSITRON-ATOM COLLISIONS
POSITRONS
RARE GASES
RESONANCE
SCATTERING