Fundamental Particles - Meson Decay Question

AI Thread Summary
The discussion centers on the decay of the pion-zero meson into two gamma rays and the calculation of their energy and wavelength. The user initially calculated the energy of the meson as 2.16 x 10^-11 J and halved it for the two gamma rays, resulting in 1.08 x 10^-11 J. Using the equation E = hc/λ, the user found a wavelength of 1.84 x 10^-14 m, which differs from the book's answer of 1.98 x 10^-14 m. Another participant confirmed the user's calculation, suggesting the book may be incorrect, leading the user to accept their result as valid. The conversation highlights the complexities of particle physics calculations and potential discrepancies in reference materials.
Magda|A380
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Homework Statement


The pion-zero meson has its mass quoted as 135.0MeV/c2.
It decays into two gamma rays:
∏0 → γ + γ
b) Assuming the ∏0meson to be initially at rest, calculate the energy and hence the wavelength of the two gamma rays.

Homework Equations


E= hc/λ

The Attempt at a Solution


Part a) just wanted me to calculate the mass in kg; which was fine, but I'm having trouble with part b).
E = 135.0 MeV, which I get to be 2.16x10-11J
I halved this value as there are two gamma rays, to get 1.08x10-11J
Using this value for E in the equation E=hc/λ, my value for λ is 1.84x10-14; however according to my book the answer should be 1.98x10-14
Could someone please tell me where I'm going wrong?
Thank you :smile:
 
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Hello Magda|A380,

Welcome to Physics Forums!
Magda|A380 said:

Homework Statement


The pion-zero meson has its mass quoted as 135.0MeV/c2.
It decays into two gamma rays:
∏0 → γ + γ
b) Assuming the ∏0meson to be initially at rest, calculate the energy and hence the wavelength of the two gamma rays.

Homework Equations


E= hc/λ

The Attempt at a Solution


Part a) just wanted me to calculate the mass in kg; which was fine, but I'm having trouble with part b).
E = 135.0 MeV, which I get to be 2.16x10-11J
I halved this value as there are two gamma rays, to get 1.08x10-11J
Using this value for E in the equation E=hc/λ, my value for λ is 1.84x10-14; however according to my book the answer should be 1.98x10-14
Could someone please tell me where I'm going wrong?
Thank you :smile:
For what it's worth, I calculated the same answer that you did (λ = 1.84 x 10-14 m, to three significant figures).
 
collinsmark said:
Hello Magda|A380,

Welcome to Physics Forums!

For what it's worth, I calculated the same answer that you did (λ = 1.84 x 10-14 m, to three significant figures).

Thanks collinsmark :)
Yeah, my books is known to be wrong sometimes and 1.84 x 10-14 m still lies within the gamma ray wavelength range; so I'll accept it as the correct answer.
 

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