Comment by stratomorph | Hacker News Reader

Comment by stratomorph | Hacker News Reader

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Unfortunately there's no mention of what it would take to produce anything more than a tabletop curiosity. It says, "After two to three weeks, the team found a small number of 'triple tracks' in the plastic..." How many is a small number? How much energy does that represent compared to the amount pumped in as electricity?

From reading the abstract on SpringerLink, I guess 9.6 MeV is released per neutron. At that neutron energy, about 650 billion neutrons per second would have to be released to produce a single watt, assuming perfect conversion. Is that reasonable? That seems high to me, but I'm not a physicist.

Without more information, it's a stretch to say this "revives hopes for cold fusion". Without being able to read the paper, it seems that the authors have avoided such claims. I guess "Evidence of Energetic Neutrons" wasn't the headline new Scientist needed. [Edit:typo]

Personally, I'm interested in fusion even if it can't be used to generate power (for instance, I liked the article about building your own fusion reactor using electrostatic confinement, which obviously eats far more power than it produces.)

Their current setup appears to be very low yield, whatever they are doing. Of course what they've built barely qualifies as proof-of-concept (assuming they are really seeing fusion). An energy production system proof-of-concept would probably be significantly different.

Going from neutron kinetic energy to usable energy (eg. for electricity production) involves many intermediate steps. You will not be able to "harvest" all of the kinetic energy. Unfortunately, I don't know the technical details to calculate those types of yields. But they are not seeing much with their detector.

650 billion is a small number. A microgram contains much more particles than that.

True, but if they were getting anything like that level of activity, their plastic detector would have been swamped. If one in a hundred million neutrons produced by this process headed through the plastic, they could have reported thousands of "triple tracks", rather than a "small number". I realize that the experiment is a small step and not intended to generate energy by itself, but it strikes me as an awfully high magnitude to be counting individually with a microscope.

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