[fluka-discuss]: Re: DPA calculation

From: Francesco Cerutti <Francesco.Cerutti_at_cern.ch>
Date: Mon, 24 Feb 2014 17:15:25 +0100

Dear Pravin Rai,

as its name (Displacements *Per Atom*) indicates, DPA is already an
intensive quantity (like density and dose), so a Cartesian/cylindrical
USRBIN indeed gives you the spatial distribution of DPA/primary weight
(making DPA/cm3 no sense, as Gy/cm3 too).
For each spatial bin, the value you get is the number of displaced atoms
divided by the number of atoms in that bin (the latter depending on the
bin size [cm3] and on the material). This means that the DPA value is
averaged over the bin: imagine that, according to your radiation field,
displacements take place only in the left half of your bin; then, adopting
a higher spatial resolution, i.e. defining a finer mesh where the number
of your bins is doubled and now right and left halves constitute a single
bin each, you will get zero DPA in the right bin and twice the previous
value in the left bin. Of course it's up to you identifying the proper
mesh resolution (which is not the first one in the example above),
according to your problem.

On a personal note, the discussion list principle is that answers are just
provided as soon as possible, so there is no need to advocate his own
question in that respect.

Best wishes

Francesco

> Respected, sir
> I am trying to calculate the DPA (Displacement per atom) in steel. I got
> data also, but i did not understand how we calculate DPA from data. In
> manual it is written there average DPA in each bin/primary weight. I
> have some doubt it is either DPA in each bin/primary weight or it is DPA
> in each bin/cm3/primary weight. Also what is the meaning of the average
> DPA.
> Please sir, reply me soon as possible.

> Regards,
> Pravin Rai

**************************************************
Francesco Cerutti
CERN-EN/STI
CH-1211 Geneva 23
Switzerland
tel. ++41 22 7678962
fax ++41 22 7668854
Received on Mon Feb 24 2014 - 18:18:18 CET