Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!csd4.milw.wisc.edu!uxc!iuvax!silver!chiaravi
From: chiaravi@silver.bacs.indiana.edu (Lucius Chiaraviglio)
Newsgroups: sci.physics,sci.research,sci.space,sci.chem,sci.space.shuttle
Subject: Re: Room Temperature fusion - possible indications?
Summary: What's worse with neutrons than protons
Keywords: radiation hazard
Message-ID: <3544@silver.bacs.indiana.edu>
Date: 28 Mar 89 05:19:28 GMT
References: <290@vlsi.ll.mit.edu> <4380@mtuxo.att.com> <1989Mar25.041342.25786@utzoo.uucp> <8299@csli.STANFORD.EDU>
Reply-To: chiaravi@silver.UUCP (Lucius Chiaraviglio)
Organization: Department of Molecular, Cellular, and Developmental Biology at Indiana University, Bloomington
Lines: 32
Xref: utzoo sci.physics:6532 sci.research:776 sci.space:10280 sci.chem:36 sci.space.shuttle:2730

In article <8299@csli.STANFORD.EDU> jkl@csli.stanford.edu (John Kallen) writes:
>I've been reading the postings about R.T. fusion with interest, and I
>am wondering: why are neutrons so undesirable in a nuclear reaction?
>Aren't protons and neutrons of the same energies just as bad? Or does
>the Coulomb repulsion of a proton by the nucleus play a role here?
>[I've forgotten all my nuclear physics :-) ]

	The neutrons aren't necessarily bad for the reaction, but they aren't
good for your health.  Protons would also be bad if they got into you, but
being charged, they will lose energy rapidly upon passing through any matter
and are therefore easily stopped, whereas neutrons, having no charge, only
lose energy slowly (generally by crashing into a nucleus, which is not
necessary for stopping protons) and therefore require considerably more
shielding to stop, and make the shielding radioactive besides.  Yes, Coulomb
repulsion of a proton by a nucleus does play a role -- the higher the atomic
number of the nucleus, the faster the proton has to be moving to react with it
instead of being deflected by it.  This means that protons moving at the
minimal speeds needed for fusion of light elements (up to boron) will not be
able to make shielding radioactive, provided that the shielding is made of
something at least as heavy as carbon (preferably a little heavier than that,
just to provide a little safety margin).  On the other hand, even very slow
neutrons can react with nuclei and thus have the potential to make things
radioactive.  Thermal neutrons (that is, neutrons moving at speeds expected
for room temperature) have been successfully used as a mutagen (source of
information:  _Genetic Mutations of Drosophila melanogaster_) (although this
may be partly due to the fact that the neutrons themselves are radioactive).

-- 
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