# Fixed source tally normalisation

**URL:** <https://openmc.discourse.group/t/fixed-source-tally-normalisation/722>\
**Category:** User Support\
**Created:** [August 22, 2020, 6:56am UTC](https://openmc.discourse.group/t/fixed-source-tally-normalisation/722 "2020-08-22T06:56:29Z")\
**Posts on this page:** 1\
**Showing post:** 6

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**Author:** ![SOC](https://avatars.discourse-cdn.com/v4/letter/s/dbc845/32.png) [@SOC](https://openmc.discourse.group/u/SOC)\
**Post date:** [January 3, 2022, 9:45am UTC](https://openmc.discourse.group/t/fixed-source-tally-normalisation/722/6 "2022-01-03T09:45:05Z")

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Hi all !  
Sorry to revive this discussion but I have doubt about the fixed source tally normalization. In [8.3. Normalization of Tally Results](https://docs.openmc.org/en/stable/usersguide/tallies.html#normalization-of-tally-results) it is written:

> As described in [Scores](https://docs.openmc.org/en/stable/usersguide/tallies.html#usersguide-scores), all tally scores are normalized per source particle simulated.

In the case of a fixed source of neutrons with 1e5 neutrons per batch, does it mean that the unit if the flux score is [particle-cm/neutron] or [particle-cm/(1e5 neutrons)] ?

I wonder after reading the answer of @Will\_Boyd in an old discussion [flux](https://openmc.discourse.group/t/flux/92) :

> However, you must scale this the flux by the ratio of the # neutrons per batch to the # neutrons emitted per second from your external source in your problem.

Thank you in advance for any clarification,  
Sabine.

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