# The protom flux

1. Feb 14, 2012

### nykon

Dear forum users,

I have a quite simple question. I have got a flux of protons measured in 1/(cm^2 s sr), I would like to have it in 1/(cm^2 s).

Best regards,
nykon

2. Feb 16, 2012

### zhermes

Then you should multiple by the number of sr

3. Feb 17, 2012

### nykon

Yes, I have got problem with sr concept:p Lets say that the distance between source and the detector is 1m. My detector has effective area of 1 cm^2. So by how many sr I should multiply my flux?

The area of the sphere with radius of 1m^2 is:

$S = 40000 \pi [cm^2]$

the effectiv area of the detector is D = 1cm^2, so:

$\frac{D}{S} = \frac{1}{40 000 \pi} = \frac{1}{125600} = 7.9 \times 10^{-6}$

So the soild angle of my detector should be:

$θ_{D} = 4\pi \times 7.9 \times 10^{-6}[sr]$

So finally:

$θ_{D} = 9.92 \times 10^{-5} [sr]$

Am I right?

Best regards,
nykon

Last edited: Feb 17, 2012
4. Feb 17, 2012

### zhermes

Yeah, I think that looks great!