Tests for “cold fusion” in the Pd-D₂ and Ti-D₂ systems at 40–380 MPa and −196-27°C

Abstract

Experiments have been conducted on the Pd-D₂ and Ti-D₂ systems at 40–380 MPa and −196-27°C to investigate the possibility that “cold fusion” occurs in palladium and titanium deuterides generated by reaction with high-pressure D₂ gas. The experiments were performed using a 4.8 mm i.d. stainless steel pressure vessel that can be operated routinely at pressures as high as 400 MPa. In experiments completed to date, reactions between high-purity Pd or Ti and D₂ were monitored with: (1) an array of three BF₃ neutron detectors, (2) an internal, type-K sample thermocouple, and (3) an internal, type-K reference thermocouple located approximately 10 cm above the sample thermocouple. Using a²⁵²Cf source, the efficiency of the BF₃ detector array was determined to be approximately 6%. During experimentation, the three neutron detectors were immersed in a water bath thermostated at 27°C. The neutron count rate, D₂ pressure, sample and reference thermocouple readings, and bath temperature were recorded continuously at time intervals ranging from 6 seconds to 10 minutes. Experimental results obtained so far range from negative to potentially significant. No sustained heat production has been observed in any experiment. Thermal pulses that persist briefly after pressurizing Pd with D₂ gas are attributable to small amounts of chemical heat released when Pd and D₂ react to form palladium deuteride. No sustained neutron flux above background was observed in any Pd-D₂ experiment. On the other hand, in a Ti-D₂ experiment just completed, potentially significant results were obtained. During this experiment, there was a period of 5 consecutive hours when count rates rose to approximately 60 counts/hour above the average background rate. This detector count rate corresponds nominally to 1000 neutrons/hour emitted from the Ti-D₂ sample. However, due to several deficiencies in our neutron detection methods and equipment, we cannot demonstrate conclusively that our experimental data are valid. Consequently, we are upgrading our neutron detection equipment in preparation for a second, improved Ti-D₂ experiment.