Re: intervals in usryield card?

From: Paola Sala <>
Date: Wed, 30 Jan 2013 09:35:12 +0100 (CET)

Dear Tristan,
when scoring neutrons, the code always respects the energy group
structure that is used for low energy neutron transport. In your case,
the energy limits chosen in the usyield card correspond to neutron groups
from 1 (20 MeV) to 155.
The details are in the manual, in the notes for the USRBDX card:

6) When scoring neutron fluence or current, and the requested energy bin
structure overlaps with that of the low energy neutron groups, bin
boundaries are forced to coincide with group boundaries and no bin can be
smaller than the corresponding group. Actually, the program uses the
requested energy limits and number of bins to estimate the desired bin
width. The number of bins above the upper limit of the first low-energy
neutron group is recalculated according to such width. Note that the
lowest energy limit of the last neutron group is 1.E-14 GeV (1.E-5 eV) for
the 260 data set.

I would like to add that, if you are interested in neutrons, it is better
to include all the energy groups in the scoring, down to the lowest


> Hi, I have been trying to score neutrons emerging from a target using a
> double differential yield on a usryield card. On the usryield card I
> specify that I want x1 variable 1 to have 99 intervals in kinetic energy.
> However once I have ran and looked at the result I find that I have 155
> intervals or some other number that I did not specify in my usryield card.
> Also the intervals are not regular in size. I selected the linear option
> and so I would have thought the intervals should be equal in size!
> I attach the input file and would be very grateful for any help on this
> matter.
> Many Thanks
> Tristan
> --
> Scanned by iCritical.

Paola Sala
INFN Milano
tel. Milano +39-0250317374
tel. CERN +41-227679148
Received on Wed Jan 30 2013 - 22:29:31 CET

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