# Question：What is the difference between flux and current?

## Summary:

calculate the flux and current of neutron by MCNP
Guys,I need to calculate the flux and current of neutron by MCNP.So what's the difference between them ,and How to calculate them?
Any ideas?

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phyzguy
Flux is a flow/area/time, so in the case of neutrons it would have units like neutrons/(cm^2 - sec). Current is a flow/time, so it would have units like neutrons/second. So the current will be the flux integrated over some surface. How you calculate theme depends on the problem given.

• LeeGru
Astronuc
Staff Emeritus
Guys, I need to calculate the flux and current of neutron by MCNP.So what's the difference between them ,and How to calculate them?
Flux is a scalar value, while current is a vector, which has a direction.

Is the question about neutron current (or particle current) or current density?

• LeeGru
Flux is a scalar value, while current is a vector, which has a direction.

Is the question about neutron current (or particle current) or current density?
I need to calculate the ratio between the total neutron current and the total neutron flux.How could obtain this value?

Flux is a flow/area/time, so in the case of neutrons it would have units like neutrons/(cm^2 - sec). Current is a flow/time, so it would have units like neutrons/second. So the current will be the flux integrated over some surface. How you calculate theme depends on the problem given.
Thank you very much.I need to calculate the ratio between the total neutron current and the total neutron flux.How could I obtain this value in MCNP