Phys. Rev. Lett. 75, 2658–2661 (1995)Search for Narrow Sum-Energy Lines in Electron-Positron Pair Emission from Heavy-Ion Collisions near the Coulomb BarrierReceived 9 June 1995; published in the issue dated 2 October 1995 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 238U +181Ta at 5.95, 6.10, and 6.30 MeV/u and 238U +232Th 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/ c2, the upper limits on cross sections obtained from the present data are significantly less than the previously reported cross sections. © 1995 The American Physical Society URL:
http://link.aps.org/doi/10.1103/PhysRevLett.75.2658
DOI:
10.1103/PhysRevLett.75.2658
PACS:
25.70.Bc, 14.80.-j
See AlsoComment: Thomas E. Cowan and Jack S. Greenberg, Comment on the APEX e+e- Experiment, Phys. Rev. Lett. 77, 2838 (1996). Reply: I. Ahmad and et al. APEX Collaboration, Ahmad et al. Reply:, Phys. Rev. Lett. 77, 2839 (1996). |
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