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Calculate the neutrino flux from the sun

  • #1
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Homework Statement



Every reaction in the sun has the energy equivalent to 0.03 mp, and generates 2 neutrinos per reaction. Calculate the number of neutrinos per second, and calculate the neutrino flux at Earth.

Astronomy generally uses the CGS (centimeter gram second) system, so just be aware of that when I do my calculations.

Homework Equations





The Attempt at a Solution



nreactions * Ereaction = Luminositysun

nreactions * mc2 = Luminositysun

nreactions * (.03 * mp)(3*1010)2 = Luminositysun

nreactions * (.03 * 1.67*10-24)(3*1010)2 = Luminositysun

nreactions * (.03 * 1.67*10-24)(3*1010)2 = 3.9*1033

nreactions * 4.51*10-5 erg = 3.9*1033 erg s-1

nreactions = 3.9*1033 erg s-1 / 4.51*10-5 erg

nreactions = 8.67*1037 reactions/s

nreactions / s * 2 neutrinos / reaction = 1.73*1038 neutrinos

Nneutrinos / Area = Fneutrino

Area = 4*pi*R2 [R = 1 AU = 1.5*1013cm]

Area = 2.83*1027cm2

So divide Nneutrinos and Area, and I get 6.1*1010 neutrinos/cm2

I looked online, and found answers which were also approx 6, but were a different order of magnitude. Did I do anything wrong?
 

Answers and Replies

  • #2
ideasrule
Homework Helper
2,266
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Your answer's right. Where did you find the values online?
 
  • #4
ideasrule
Homework Helper
2,266
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That link gives 6.296541*10^14 /(m^2*s). Your answer is in /(cm^2*s).
 
  • #5
188
0
That link gives 6.296541*10^14 /(m^2*s). Your answer is in /(cm^2*s).

right right, right you are, thanks
 

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