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Photon and particle reaction

  • Thread starter faen
  • Start date
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1. Homework Statement

Consider the production of the K+ in the reaction: [tex]\gamma[/tex] p --> Κ+ Λ


What will be the minimal [tex]\gamma[/tex] energy if the proton is not free but is bound in the nucleus? Take into account the Fermi motion with p=250 MeV/c.

2. Homework Equations

proton mass = 770 MeV
Kaon mass = 494 MeV
hyperon mass = 1100 MeV

3. The Attempt at a Solution

I cant find anywhere in my book explaining what fermi motion is. The binding energy depends on how big the nucleus is, which isnt specified unless fermi motion does so.
 

Answers and Replies

pam
455
1
Fermi motion means the proton can be heading toward the beam with p=250.
Put this into the total momentum for the initial gammas p state.
 
140
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Thank you the answer. Should i convert the fermi motion into energy units, and use the concept of conservation of energy to calculate the minimum [tex]\gamma[/tex] energy? The task mentions something about the proton being bound to a nucleus. Do i somehow have to take that into account in the calculation?
 
pam
455
1
The proton being bound is taken care of b using the Fermi momentum given.
Everything is in MeV, with c=1. You have to calculate the Fermi energy, given by [tex]E_p^2=p^2+M^2[/tex].
The equation for the threshold gamma energy k is
[tex](k+E_p)^2-(k-p)^2=(M_\Lambda+m_k)^2[/tex].
 
Last edited:

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