I wrote: I have not yet looked closely at Holmlid's results, but I don't write them > off. I'm keeping a distinction in my mind between his experimental > observations and his theoretical speculations. >
I have now had a chance to look more closely at Leif Holmlid's 2013 paper, "Direct observation of particles with energy >10 MeV/u from laser-induced fusion in ultra-dense deuterium", from which I quoted a few days ago about there being ~ MeV particles being detected. Bob Higgins corrected me and pointed out that it was time-of-flight spectrometry and that the radiations being detected were claimed to be consistent with ~ MeV u-1 particles, on the basis of the nanosecond times of flight. Here is what I can say after reading through the paper more carefully. Holmlid is irradiating a target of copper or nickel with a laser. Above the target is a tube through which hydrogen or deuterium gas issues after having passed through a plug of porous potassium catalyst. Holmlid assumes, without elaboration, that the catalyst has created "ultra-dense deuterium" at that point. It seems Holmlid has constructed his own custom time-of-flight spectrometer using an oscilloscope together with a charged collector plate attached to a chamber he has used in other experiments. He does not report a calibration step for his custom time-of-flight spectrometer, e.g., using americium. It is a little hard to imagine trusting one's own time-of-flight spectrometer if one is not already an expert in this kind of measurement. It is yet harder to imagine trusting a custom instrument that has not been calibrated. Experts in the field using purchased spectrometers will surely calibrate using natural radiation sources of known energy. Holmlid shows great courage in reasoning from first principles in this paper and in others of his that I've had a chance to read. In this paper he assumes, without much discussion, that he is seeing dd fusion. He does not think he is seeing neutrons, as weak interactions are expected to occur with the aluminum degrader material (his meaning here was a little unclear). It is possible and perhaps even likely that Holmlid is really seeing some kind of radiation. When he places an aluminum degrader before the radiation, or uses a strong magnet, he still gets a signal, which probably means the particles are not electrons, consistent with his conclusion. But I will not trust any of his conclusions until he brings in someone who is skilled at measuring charged particle radiation and who is not a frequent collaborator. Eric
