Physical Review Letters · 1995 · 37 citations · 13 references
Natural SciencesPhysicsNuclear PhysicsParticle PhysicsSpectroscopyCollider PhysicsCross Section DataHeavy-ion PhysicsNuclear DecayRadioactive DecayCollision Cross SectionsElectron-positron CollisionsExperiment ReportingIon-ion CollisionsUpper Bounds
The first results are presented from a new experiment, APEX, designed to study the previously reported sharp lines in sum-energy spectra of positrons and electrons produced in collisions of very heavy ions. Data were collected for ${}^{238}$U $+$${}^{181}$Ta at 5.95, 6.10, and 6.30 MeV/u and ${}^{238}$U $+$${}^{232}$Th at 5.95 MeV/u. In none of our analyses is any evidence found for sharp sum-energy lines. For the specific case of the isolated decay of a neutral particle of mass 1.4--2.1 MeV/ ${c}^{2}$, the upper limits on cross sections obtained from the present data are significantly less than the previously reported cross sections.
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Observation of a Peak Structure in Positron Spectra from U+Cm Collisions
J.E. Schweppe, A. Gruppe, H. Bokemeyer et al. · Physical Review Letters · 1983 · 329 citations
Anomalous Positron Peaks from Supercritical Collision Systems
T. E. Cowan, H. Backe, Marianne H. Begemann et al. · Physical Review Letters · 1985 · 298 citations
Narrow positron lines from U-U and U-Th collisions
M. Clemente, E. Berdermann, P. Kienle et al. · Physics Letters B · 1984 · 268 citations