Exploring possible coupling between phonons and internal nuclear states

Abstract

During the past three decades, there were approximately 25 different anomalies in the field of condensed matter nuclear science reported by researchers. One example involves collimated X-rays coming from metal samples with vibrations without a clear explanation or understanding of the underlying physics involved. Another example involves unexpected non-exponential decay of radioactive sources. These anomalies have motivated a research effort by my Ph.D. advisor at MIT, Professor Peter Hagelstein, to investigate the physical phenomena involved. Hagelstein came up with a theory predicting coupling between phonons and internal nuclear states, leading to excitation transfer between nuclei. The aim of this Ph.D. thesis is to experimentally test Hagelstein's theory. In this research, we used Co-57 as the sample to investigate the nuclear excited states. Unexpected non-exponential decay was seen in the first attempt to look for excitation transfer effect. Heat pulse can trigger X-ray signal increments. We performed angular anisotropy experiments which appears to support the conjecture that slow resonant excitation transfer occurs for the 136 keV excited state of Co-57. We also performed delocalization experiments which appears to support the conjecture that fast excitation transfer occurs for the 14.4 keV excited state of Co-57. Our conclusion is that the experimental data are not inconsistent with Hagelstein's theory.