Fusion Science and Technology / Volume 43 / Number 1 / January 2003 / Pages 122-127
A series of lead vials of internal volume 1.0 cm3 were charged with ~200 mg of carbon catalyst containing 0.5% Pd and 0.4% Pd. The vials were clamped to stainless steel manifolds on a vacuum line, then pumped out and filled with high-purity H2 or D2 at a pressure of 152 cm Hg and a temperature of 23°C. Several vials contained ordinary activated carbon instead of palladium-carbon, and some vials contained only H2 or D2. All the vials were stored in a sandbox heated to ~200°C for times up to 45 days before mass spectrometer measurements of 3He and 4He were made. No evidence was found for the high concentrations of 4He claimed in similar experiments by several other researchers. The upper limit for the concentration excess of 4He in D2 in vials containing palladium-carbon is 11 ppt (parts per trillion) at the 95% confidence level. This limit for 4He may be compared with previous claims in similar experiments of 100 ppm (parts per million) by Case and 11 ppm by George and McKubre et al.