# Neutrinos penetration of neutron stars or white drawfs

## Main Question or Discussion Point

Neutrinos can pass through solid objects like the earth easily, and a light-year of lead would only stop half of them from passing through.

What about something very dense like a white drawf or neutron star? How readily can neutrinos penetrate that? What % flux reduction would be achievable if neutrinos passed through a neutron star?

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bcrowell
Staff Emeritus
Gold Member
The density of nuclear matter is greater than the density of ordinary matter by about a factor of 10^15. So I would guess the answer would be that neutrinos would penetrate into a neutron star by roughly (1 light-year)*10^-15=10 m.

The density of nuclear matter is greater than the density of ordinary matter by about a factor of 10^15. So I would guess the answer would be that neutrinos would penetrate into a neutron star by roughly (1 light-year)*10^-15=10 m.
Is it the same for neutrinos and anti-neutrinos?

Bob S

The density of nuclear matter is greater than the density of ordinary matter by about a factor of 10^15. So I would guess the answer would be that neutrinos would penetrate into a neutron star by roughly (1 light-year)*10^-15=10 m.
thanks, according to this link it's 22 light years.

Neutrinos
This was an expected result, since the mean free path of a neutrino in matter is about 22 lightyears in lead and having the earth in the path makes little ...
hyperphysics.phy-astr.gsu.edu/Hbase/particles/neutrino.html

I'm not sure there's a linear proportion of density and penetration.

From bcrowell:
The density of nuclear matter is greater than the density of ordinary matter by about a factor of 10^15. So I would guess the answer would be that neutrinos would penetrate into a neutron star by roughly (1 light-year)*10^-15=10 m.

From Bob S
Is it the same for neutrinos and anti-neutrinos?

thanks, according to this link it's 22 light years.

Neutrinos
This was an expected result, since the mean free path of a neutrino in matter is about 22 lightyears in lead and having the earth in the path makes little ...
hyperphysics.phy-astr.gsu.edu/Hbase/particles/neutrino.html

I'm not sure there's a linear proportion of density and penetration.
I think that a neutrino incident on a neutron has an allowable final state (proton plus electron), while the anti-neutrino incident on a neutron has none. This should be reflected in the total cross section.

Bob S

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