High-sensitivity measurements of the excitation function for Bhabha scattering at MeV energies

Journal Article · Fri Sep 01 04:00:00 EDT 1989 · Physical Review (Section) D: Particles and Fields; (USA)

DOI:https://doi.org/10.1103/PhysRevD.40.1397· OSTI ID:5593487

Tsertos, H; Kozhuharov, C; Armbruster, P; Kienle, P ^[1]; Krusche, B; Schreckenbach, K ^[2]

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1. Gesellschaft fur Schwerionenforschung (GSI), Planckstrasse 1, D-6100 Darmstadt, Federal Republic of Germany (DE)
2. Institut Max von Laue-Paul Langevin (ILL), 156 X Centre de Tri, 38042 Grenoble CEDEX, France

Using a monochromatic {ital e}{sup +} beam scattered on a Be foil and a high-resolution detector device, the excitation function for elastic {ital e}{sup +}e{sup {minus}} scattering was measured with a statistical accuracy of 0.25% in 1.4-keV steps in the c.m-energy range between 770 and 840 keV (1.79--1.86 MeV/{ital c}{sup 2}) at c.m. scattering angles between 80{degree} and 100{degree} (full width at half maximum). Within the experimental sensitivity of 0.5 b eV/sr (c.m.) for the energy-integrated differential cross section no resonances were observed (97% C.L.). From this limit we infer that a hypothetical spinless resonant state should have a width of less than 1.9 meV corresponding to a lifetime limit of 3.5{times}10{sup {minus}13} s. This limit establishes the most stringent bound for new particles in this mass range derived from Bhabha scattering and is independent of assumptions about the internal structure of the hypothetical particles. Less sensitive limits were, in addition, derived around 520-keV c.m. energy ({similar to}1.54 MeV/{ital c}{sup 2}) from an investigation with a thorium and a Mylar foil as scatterers.

• OSTI ID: 5593487
• Journal Information: Physical Review (Section) D: Particles and Fields; (USA), Journal Name: Physical Review (Section) D: Particles and Fields; (USA) Vol. 40:5; ISSN PRVDA; ISSN 0556-2821
• Country of Publication: United States
• Language: English

Related Subjects

645101* -- High Energy Physics-- Particle Interactions & Properties-Experimental-- Electromagnetic Interactions & Properties
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
ALKALINE EARTH METALS
ANGULAR DISTRIBUTION
BEAMS
BERYLLIUM
BHABHA SCATTERING
CROSS SECTIONS
DIFFERENTIAL CROSS SECTIONS
DISTRIBUTION
DOPPLER BROADENING
ELASTIC SCATTERING
ELECTRON-POSITRON INTERACTIONS
ELEMENTS
EXCITATION FUNCTIONS
FORM FACTORS
FUNCTIONS
INTERACTIONS
LEPTON BEAMS
LEPTON-LEPTON INTERACTIONS
LIFETIME
LINE BROADENING
METALS
PARTICLE BEAMS
PARTICLE INTERACTIONS
PARTICLE PROPERTIES
POSITRON BEAMS
SCATTERING