Re: [fluka-discuss]: How to calculate the LET?

From: Paola Sala <paola.sala_at_mi.infn.it>
Date: Mon, 22 Oct 2018 10:43:03 +0200

Hello

I'll try to give some hints on how to proceed, however please refer to the
detailed instructions on the use of USRYIELD that are in the manual.

First of all, USRYIELD scores on a boundary between regions.
So, you need to define and choose your boundary, say betweern REG1 and REG2.

Then, USRYIELD scoring is defined by TWO variables and the result
is double differential wrt those two variables.

Results will be given in many intervals ("as a function of") of the first one
(called ie in the manual), while the second variable (ia)
defines a single interval. A list of possible variables is in the manual.

For instance: one can get a distribution of LET (ie=let=23)
in the range 0.0 to 100.0 (keV/(micron g/cm 3 )) in 100 intervals,
selecting particle energy (ia=energy=1) in the interval [0, 0.1] GeV

What is the output quantity?
There are many possible choices (ixa, see the manual),
however for most applications ixa = 3: plain double differential yield
d2 N / d x1 d x2 (this is not the first one shown in Flair, be careful).
Finally, one has to choose in which material the LET should be calculated.
In this example we take Water (mat=27)

In this example, one will get: for each LET sub-interval,
the number of particles having LET in that sub-interval
and energy between 0. and 0.1 GeV
normalized (beware to normalization)
per primary particle and per unit interval of the TWO quantities.

In the example, particles/(keV/(micron g/cm 3 ))/GeV/primary
(because Fluka works in GeV).
Therefore, if you need the TOTAL number of
particles/(keV/(micron g/cm 3 ))/primary, you have to "integrate" over the
second variable, which means multiply by the interval in the second
variable (0.1 GeV). This can be done automatically by adding a
normalization.

If the user does not need to set limits in the second ("ia") variable,
he/she should choose an "easy" one (i.e. kinetic energy..), with safe
limits not to lose particles, and, if possible, with unit or "simple"
range (0-1 GeV for instance)

The example described here translates into:
(how... is in the manual, or in Flair)
It would be improved by setting log scale on ie (in the manual...)
USRYIELD 123. ALL-CHAR -69. REG1 REG2 10. LETChE
USRYIELD 100.00 0.00 100. .1 0.0 2703. &
Of course this assuming WATER is material 27 (look in the output if you are
in doubt).

Summing up of output files, translation into human-readable,
plotting can go through FLAIR or through the usysuw program
in the flupro directory.

Hope this helps
Paola


>
> Dear
> experts:                                                                
> How to calculate the LET by the  USRYIELD scoring card?   
> Thanks     
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Paola Sala
INFN Milano
tel. Milano +39-0250317374
tel. CERN +41-227679148

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Received on Mon Oct 22 2018 - 12:18:05 CEST

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