Further attempts to isolate superheavy elements in the meteorite Allende

The search for superheavy elements /SHE/ in the carbonaceous chondrite Allende was continued. This time we carried out a thermochromatographic separation at 1050 °C in O₂-, resp., H₂-gas flow. The volatile fraction /mostly Pb/ was collected on a Pt-foil or trapped in KOH-solution. The heavy element probes were investigated for spontaneous fission activities. We observed zero spontaneous fission decays during 421 days. This yielded an upper limit of 2.9 fission x kg^–1 x year^–1 /95% confidence limit/. We were unable to confirm the existence of a spontaneous fission activity in the meteorite Allende.