Ortho-para conversion of hydrogen in copper as origin of time-dependent heat leaks

Abstract

It is shown that H2 precipitated into bubbles in copper undergoes ortho-para conversion. This conversion, at a rate of about 2%/h, and the hydrogen content are detected quantitatively by the time-dependent heat release associated with them. The heating is comparable to the time-dependent heat leak observed in copper nuclear refrigerators. The amount of H2 necessary to explain the data lies between 10 and 100 ppm. Due to its much smaller conversion rate and the smaller energy conversion, the heat released from D2 in copper is essentially time independent fort<100 h and is up to two orders of magnitude smaller than the one for H2.