[ExI] Neutrino interaction web
rpwl at lightlink.com
Fri Mar 4 18:25:47 UTC 2011
Adrian Tymes wrote:
> On Fri, Mar 4, 2011 at 5:54 AM, Richard Loosemore <rpwl at lightlink.com> wrote:
>> I wouldn't go that far :-), but the collision cross section for neutrinos is
>> estimated to be such that if you want to catch a significant fraction of
>> them you need *roughly* a 1 light-year thick sheet of lead.
> Ah, but that's with atoms. All that empty space.
Gee, Adrian: you got a one-light-year-thick wall of lead there, which
has been compressed into a nice convenient-sized sheet! 8-) I reckon
each neutrino will hit, what? 10^^17 nuclei on its way through??? I
don't think the empty space is your problem. :-)
>> So, I don't see any problem with Adrian's ideas except that you need to take
>> a 1 light-year thick sheet of lead then compress it to make a thin sandwich
>> that we can install in orbit, to collect the sun's neutrino output.
>> Shouldn't be too difficult. Bit of engineering, is all.
> Neutron stars are compressed matter of that sort. Except they're balls, not
> sheets, and unless you've got a way to get them to spread out despite their
> own gravity pulling them into a ball is the tricky part.
Okay lets see. Average density of a neutron star is 5^^17 kg/m3.
Average density of lead is about 1^^4 kg/m3.
So to make the light year thick sheet of lead have the same cross
sectional density as a neutron star you would have to compress it in one
dimension by a factor of about 1^^14.
One light year is about 10^^16 meters.
So that is pretty good! You would only need about 100 meters of neutronium.
Comparable to the size of a neutron star, in fact. So if you want to
capture neutrinos, a neutron star would do quite nicely.
So, next step. You've got your neutron star, and it is definitely
collecting a lot of the neutrinos from the sun: now what do you do with
(Meanwhile, better hurry, because I think your neutron star is eating
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