RE: Defining Californium source

From: Anton Lechner <>
Date: Sun, 1 Sep 2013 22:05:22 +0000

Dear Saneesh,

It is certainly possible to define such a source. You will need a customized source routine to sample energy, position and direction of the neutrons. I advice to first give a look to the following lecture (see "User-defined source routines"):

In addition, there have been previous discussions on the FLUKA list on the same topic. See e.g. following link:

Now concerning your second question on the "number of primaries". If I understand you correctly, you would like to set up primary particles at different points in time (even though I don't understand the reasoning behind). During particle transport in FLUKA, time is accounted for via the "age" of primary and second particles which is always given with respect to the point in time when the primary particle was set up. Since different primary events are independent from each other there is no correlation in the timing across events. Apart from this, might it be that your question is rather related to normalization? If you have for example a radioactive source, then you need to normalize results with the corresponding activity (and you don't incorporate the time of disintegrations in the simulation).

Cheers, Anton

From: [] on behalf of []
Sent: 28 August 2013 08:26
Subject: Defining Californium source

Dear Fluka experts,

              I am trying to simulate the energy spectrum of neutrons from
Californium-252. But the energy spectrum of neutrons from this
source is continuous, changing from ~100KeV to ~10 MeV. Is it
possible to define such a source using Fluka?
Also can anybody please tell me the meaning "number of primaries"? If I
define the number of primaries equal to 10,000, does it mean all the
10,000 interact with the target without any time delay?
Is it possible to define the same 10,000 particle with 10 particle/ns such
that it will take 1000ns to score the full 10,000 particles?

Please help me to solve these problems

Thanks in advance

Saneesh N
Received on Mon Sep 02 2013 - 09:18:13 CEST

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