Dear FLUKA experts,
I am simulating a three-layer cylindrical geometry (layer 1, 2, and 3), and I need to scale the intensity of the monoenergetic isotropic cylindrical carbon ion beam differently for each layer. The intensity of the beam is layer 2 should be a lot lower than layer 1 and 3. I have a scaling factor for each layer, but I could not find a way to implement it. There is only beam intensity in particles per second for radioactive decay available in the FLUKA manual. Does anyone have an idea how I can implement it?
Thank you so much in advance.
Cheers,
Jing
Dear Jing,
can you please provide a some additional details on your model and its geometry. What is the source of primary particles (carbon beam?). What is your interaction geometry (beam dump, target)? Is 3-layered cylindrig geometry describes your source or beam propagation/scoring area?
Do you have any preliminary Fluka/Flair project or sketch?
Kind regards,
Illia
Hi Illia,
the primary source is a cylindrical carbon beam line source in the z-direction, in the middle of the three-layer cylindrical geometry. The height of the three-layer cylinder is in the z-direction as well. The middle layer of the cylinder is the target where energy is scored. Since the intensity of the beam for each layer differs, I need three line sources, but I have tried to implement a single line source for all three layers.
DEFAULTS PRECISIO
BEAM 0.7271 10000.0 HEAVYION
*Define the beam position
BEAMPOS 0. 0.001 0. 124.2 CYLI-VOL
*Ion Definition
HI-PROPE 6. 12.
GEOBEGIN COMBNAME
0 0
*Black body
SPH blkbody 0.0 0.0 0.0 1000000.
*Void sphere
SPH void 0.0 0.0 0.0 100000.0
RCC phantom 0.0 0.0 0.0 0.0 0.0 124.2 57350.0
RCC cutbox 0.0 0.0 61 0 0 2.2 57350.0
*Cylindrical air
RCC target 0.0 0.0 62.0 0.0 0.0 0.2 57350.
END
*Black hole
BLKBODY 5 +blkbody -void
*Void around
VOID 5 +void -phantom
PHANTOM 5 +phantom -cutbox
CUTBOX 5 +cutbox -target
*Target
TARGET 5 +target
END
GEOEND
Dear Jing,
do you need coaxial carbon beams of same energy but various intensity?
You can do it as an overlap of 3 anular beams. To have 3 sources simultaneously you can use combination of SPECSOUR (type Beamspot) and BEAMSPOT cards
se page 26 of the lecture:
Or do you need something else?
Kind regards,
Illia
Dear Illia,
yes, I need coaxial carbon beams of same energy of various density at the different layers, so the three cylindrical beams are located at different positions. I don’t quite understand the use of 3 annular beams and how can I position my cylindrical beams at different z-values with SPOTPOS, SPOTDIR or/and BEAMPOS.
Cheers,
Jing
Dear Jing,
can you please provide some schematics of your experiment, so I can be sure that I understand your problem.
In general with SPOTPOS card (for use case see page 26) you can combine 3 sources (as described in the lecture). This 3 anular sources with simmetry and propagation along the aixs Z with different internal end external radia will provide you cillindrical beams, that simulate your sheath. Than sure, the easiest wat will be to have your geometry symmetric to axis Z.
Cheers,
Illia
Dear Illia,
attached is my geometry. The first cylindrical source spans in the z-direction from 0 to 60 cm with an intensity of 10, the second one spans 60 cm to 70 cm with an intensity of 1 and the last one spans 70 cm to 130 cm with an intensity of 10 as well. The beam should travel in the x-y plane. I don’t need 3 point-like sources, but rather 3 volume-distributed ones.
The simulated beam should look something like this.
Cheers,
Jing
Dear Jing,
so several coaxial sources aligned along z axis can be a solution for you.
You can change the propagation direction from positive to negative using “type” parameter in BEAMPOS card and set up as meny sources as you need. You also have an option to set their intensity ratio, by using “Sequentially weighted” mode in SPECSOURCE card, where you define the number of sources.
Kind regards,
Illia
Dear Illia,
does that mean I have to set up each source myself, and cannot just use a volume-distributed source? Could I set up a volume-distributed source if I write an extra source.f?
Cheers,
Jing
Dear Illia,
is it possible to set up a few BEAMPOS cards and assign them to the respective SPOTBEAM?
Cheers,
Jing