
#1
Jun1411, 10:21 AM

P: 131

Like the question says, would a neutrino be stopped by the very high density matter in a neutron star?
IH 



#2
Jun1411, 10:57 AM

Emeritus
Sci Advisor
PF Gold
P: 5,500

Googling shows that there are various people trying to calculate this, e.g.,
http://arxiv.org/abs/astroph/9806285 http://prola.aps.org/abstract/PR/v133/i4B/pB1046_1 Just as a first guess, I would have expected by default that a neutrino entering a neutron star would have about the same probability of being absorbed as a neutrino entering a mainsequence star, since they encounter about the same amount of mass. The abstract of the second paper talks about a mechanism that produces a deviation from this expectation, causing a neutron star to be completely transparent to neutrinos with low energies. 



#3
Jun1411, 12:26 PM

Mentor
P: 15,625

The first guess is pretty close. And since we know that probability is low, we know that neutron stars are largely transparent to neutrinos.




#4
Jun1411, 12:55 PM

P: 131

Would a Neutron Star Stop a Neutrino?IH 



#5
Jun1411, 02:10 PM

P: 1,262

The mean free path (l) is the average distance a neutrino will go before colliding. If the mean free path is smaller than 10km, you can expect the neutrino to collide; otherwise you would expect it to escape freely. ~~~~~ The exact answer depends on the details of neutron star structure which is still uncertain. 



#6
Jun1411, 02:29 PM

Sci Advisor
PF Gold
P: 4,863

Given that it takes light years of lead to reach 50% chance of absorbing a neutrino, that is enough to conclude that neutrons stars have a small chance of stopping a neutrino. 



#7
Jun1411, 02:41 PM

P: 131

IH 



#8
Jun1411, 04:20 PM

Sci Advisor
PF Gold
P: 4,863





#9
Jun1611, 01:15 AM

Sci Advisor
PF Gold
P: 4,863

So, unless there is a flaw in the above, my previous answers were incorrect. 



#10
Jun1611, 04:20 PM

P: 1,262





#11
Jun1611, 04:30 PM

Sci Advisor
PF Gold
P: 4,863





#12
Jun1611, 05:10 PM

P: 14





#13
Jun1611, 05:21 PM

Sci Advisor
PF Gold
P: 4,863





#14
Jun1611, 05:30 PM

P: 14





#15
Jun1611, 05:35 PM

P: 14





#16
Jun1611, 05:37 PM

Sci Advisor
PF Gold
P: 4,863





#17
Jun1611, 05:46 PM

Sci Advisor
PF Gold
P: 4,863

From what I see of the recent Japanese results, there is no real surprise at all  just verification of muon>electron neutrino oscillation, and possible quantification of the last previously unknown neutrino mixing angle. There may be relevance for matterantimatter symmetry, but I just don't see anything that would imply anomalously high cross sections for low energy neutrino interactions.




#18
Jun1611, 06:11 PM

P: 14




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