The search for cosmic strangelets with the supersonic concorde and with JACEE\u27s circumpolar balloon flight in Antarctica

The search for cosmic strangelet nuclei was carried out by two experiments with emulsion chambers. A balloon-borne JACEE emulsion chamber was flown at 3.5 g/cm2 for 200 h in Antarctica (JACEE-10 experiment) and the Concorde flights were made by ECHOS at an atmospheric depth of 110 g/cm2 between Paris and New York. No nuclei with Z ≥ 30 survived after traversing 60-120 g/cm2 of the detector materials in the JACEE instruments. No evidence for a long mean free path were found in the zenith angle distribution for Z/β ≥ 26 nuclei. The exposure factor used by the JACEE was 72 m2 h sr. The intensity upperbounds, I ≤ (2.2-9.7) × 10-2/m2 h sr, were obtained for strangelets having an atmospheric attenuation length of 220-50 g/cm2, which corresponds to the case for mass number A = 100-10000 and Z/β ≥ 13. Concorde experiments (ECHOS) used both a thin and a thick emulsion chamber. The total exposure was 209 m2 h sr and no candidates with charge Z ≥ 30 were found. The largest track had Z/β = 28.6 ± 1.29 with β ∼ 1. Nuclei observed with charge 13 ≤ Z ≤ 30 were consistent with the survival intensity of ordinary nuclei. The flux bounds from the ECHOS experiments were I ≤ (2.1-5.0) × 10-2/m2 h for strangelets with mass number 100≤A≤1000. © J.C. Baltzer AG, Science Publishers

Interpreting anomalous electron pairs as new particle decays

In heavy particle decays found in cosmic ray interactions recorded in the JACEE emulsion chambers, multiple electron pairs were previously reported. These pairs apparently originated from conversions of photons emitted in the decays. It is difficult to explain the overall properties of these decays in terms of known heavy particle decay modes. A recently published compilation of low-energy nuclear data suggests the presence of excess electron pairs with invariant mass of about 9 MeV/c2, which may be explained by postulating the existence of a new neutral boson decaying into the electron pair. The feasibility of explaining the JACEE electron pairs with this hypothesis is presented