# Gamma ray colliding with an electron

## Homework Statement

A beam of gamma rays of energy 1.00 MeV are aimed at a set of freely moving gold particles. The gamma rays reflected back have an energy of 0.2035 MeV. How is this result consistent with the model of a gamma ray reflecting from an isolated electron initially at rest?

## Homework Equations

E^2-P^2c^2=m^2c^4

## The Attempt at a Solution

I've tried a few ways using Compton scattering but to no avail.
Determining the momentum of the gamma ray.

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Redbelly98
Staff Emeritus
Homework Helper

## Homework Statement

A beam of gamma rays of energy 1.00 MeV are aimed at a set of freely moving gold particles. The gamma rays reflected back have an energy of 0.2035 MeV. How is this result consistent with the model of a gamma ray reflecting from an isolated electron initially at rest?

## Homework Equations

E^2-P^2c^2=m^2c^4

## The Attempt at a Solution

I've tried a few ways using Compton scattering but to no avail.
Determining the momentum of the gamma ray.
Welcome to Physics Forums.

Can you show your work on the Compton scattering calculation? For me, it worked out. Make sure that you:

1. Don't just subtract the two given energies, and use that to determine Δλ.
2. Do use the mass of an electron, not a gold nucleus or atom.

Thank you for your reply. After a few more tries I was able to solve it using Compton scattering with a reflection of 180.

:)