# B Gamma photon ionization

1. Apr 8, 2017

### Daniel Petka

Gamma rays scatter and ionize atoms, which stretches out their wavelength, right? How many ions could a single gamma ray photon create before it's absorbed due to the photoelectric effect?

2. Apr 8, 2017

### Vanadium 50

Staff Emeritus
How long is a piece of string?

3. Apr 15, 2017

### Daniel Petka

The major difference between a string and a gamma photon is that gamma photons have a certain energy. The length of the "string" doesn't apply to any model of photons. (unless we're talking about the string theory :p)

4. Apr 15, 2017

### Staff: Mentor

Just as there is no particular upper bound on the length of a string, there is no particular upper bound on the energy of a gamma photon.... So Vanadium50's response is not unreasonable.

But were you trying to ask how many ions could be created by a photon of given energy passing through a homogeneous medium? That's a more specific question that's more likely to get a satisfactory answer.

5. Apr 22, 2017

### Daniel Petka

Exactly

6. Apr 22, 2017

### Daniel Petka

To be specific I would say about 1 TeV

7. Apr 22, 2017

### gleem

Now we can take Vanadium 50's response and change it to ," into how many pieces can you divide a string?". A gamma ray has several competing modes of interactions at least including pair production, Compton scattering, photoelectric effect and nuclear photodisintegration whose probabilities of occurrence are highly dependent on energy. A photon can only be absorbed by the PE with significant probability when its energy is close to the binding energies of the atomic electrons. So into how many pieces can you divide a string? as many as you want.

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