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

Journal Article · Sat May 01 04:00:00 EDT 1993 · Bulletin of the American Physical Society

OSTI ID:281242

Dou, L; Kauppila, W E; Kwan, C K; Stein, T S

We have measured absolute values of elastic differential cross sections (DCS`s) for positron (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 were 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 for e{sub +}-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. supports the Higgins and Burke prediction. These predictions and the present observations suggest the existence of a new type of atomic scattering resonance.

• OSTI ID: 281242
• Report Number(s): CONF-9305421--; CNN: GRANT PHY90-21044
• Journal Information: Bulletin of the American Physical Society, Journal Name: Bulletin of the American Physical Society Journal Issue: 3 Vol. 38; ISSN 0003-0503; ISSN BAPSA6
• Country of Publication: United States
• Language: English

Related Subjects

66 PHYSICS
ARGON
DIFFERENTIAL CROSS SECTIONS
ELASTIC SCATTERING
KRYPTON
NEON
POSITRON-ATOM COLLISIONS