exc5 - Introduction to Astrophysics 0321.3108 Exercise 5 1...

Info iconThis preview shows pages 1–2. Sign up to view the full content.

View Full Document Right Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: Introduction to Astrophysics 0321.3108 Exercise 5 1. Nuclear reactions occur when nuclei are within range of the “strong nuclear force”, i.e., “strong interactions”. In the first step of the p-p chain one proton is transformed to neutron. The reaction is mediated by the exchange of virtual pairs of pions, m π c 2 = 135 MeV. The Heisenberg uncertainty principle for virtual is Δ t · Δ E ≤ ~ . Note that for real particles it is ≥ ~ . Find the maximum distance that the pions pair can travel. This is an estimate for the range of the strong interaction. 2. We saw in class that the nuclear reaction rate in a star between particles A and B is: R AB = n A n B < σv > where < σv > = 1 ( k B T ) 3 / 2 8 πμ 1 / 2 Z ∞ S ( E ) f ( E ) dE , (1) where σ is the cross section, v is the relative velocity of the particles, S ( E ) is a function that contains the “physics details” in units of energy × area , μ is the reduced mass and f ( E ) = e- E/ ( k B T ) e- √ E G /E , (2)...
View Full Document

{[ snackBarMessage ]}

Page1 / 2

exc5 - Introduction to Astrophysics 0321.3108 Exercise 5 1...

This preview shows document pages 1 - 2. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online