Siyuan Lu’s scientific contributions

On May 20, 2017, we started a series of experiments with the goal of observing vibrationally induced excitation transfer of the 14.4 keV nuclear state from excited Fe-57 to ground state Fe-57 nuclei. A steel plate with a Co-57 substrate on the front surface was vibrated by a piezoelectric transducer near 2.21 MHz; and emission in the X-ray region was recorded with an Amptek X-123 detector on the front side, a scintillator/photomultiplier detector on the back side, and a Geiger counter on the back side. The experiments provided a negative result for the originally sought ultrasonically induced excitation transfer effect, but instead showed non-exponential time histories for photon counts on all three detectors. Specifically, increased emission of the 14.4 keV gamma, Fe Kα and Kβ X-rays was observed at early time. This enhancement was present at the start of the experiments at about 19% above expected levels for the 14.4 keV gamma, and about 17% for the Fe K-alpha, with the enhancement decaying away with a time constant of about 2.5 days. Emission on the Sn Kα was consistent with the expected exponential decay of Co-57 at the 1% level. Non-exponential decay with an enhancement at early time was also seen for the weak Fe Kα escape peak, and in the back- side Geiger counter data; and a reduction at early times was seen on the higher energy channels of the scintillator/photomultiplier detector counter both looking at the back side. The observed non-exponential decay is connected with the tightening of bolts on wooden clamps on the corners of the steel plate, which apply mechanical stress to the sample. Candidate interpretations are considered, in which the stress induced in the steel results in scattering and generation of THz phonons by dislocations, and in which phonon–nuclear coupling mediated by THz phonons leads to the transfer of nuclear excitation to other nuclei (“excitation transfer”), which can cause spatial delocalization of the source and angular anisotropy of the photon emission.

Excess heat has been reported in cold fusion experiments since 1989; however, there is at present no accepted explanation for what mechanisms are involved. Over the past decades a general theory has been developed which seems applicable to excess heat and other anomalies systematically; but in this case we do not yet have unambiguous experimental support for the phonon–nuclear coupling and enhanced up-conversion and down-conversion mechanism. This has motivated experimental studies with which we hope to develop relevant experimental results from which clear tests of theory can be made. A facility has been developed with which we are able to induce vibrations in metal plates from about 10 kHz up to about 10 MHz and then measure the relative displacement. With a high-power piezo transducer we have driven a steel plate at 2.23 MHz to produce a vibrational power of 100 W. We are able to detect X-rays with film, scintillator and camera, with low-cost sensitive scintillator/PMT detectors, and with an Amptek X-123 detector. We also have detectors that can see gamma and neutron emission.