Re: [fluka-discuss]: Antiproton secondaries, Energy distribution

From: George Kharashvili <>
Date: Tue, 21 Feb 2017 09:19:01 -0500 (EST)

Dear Sebastian,

You have correctly chosen USRBDX card for scoring the boundary crossing fluence. It can also be used to score boundary crossing current and angular distribution.
Please take a look at the scoring lecture slides from the last FLUKA course

What the units are on your plot is difficult to tell, because you have several plotting options to pick from in flair. Generally "The results of a USRBDX boundary crossing estimator are always given as DOUBLE DIFFERENTIAL distributions of fluence (or current) in energy and solid angle, in units of cm-2 GeV-1 sr-1 per incident primary" - FLUKA manual. The above slides and the notes at the bottom of the USRBDX page in the manual should help you decide what quantities to score and plot. If I understand it correctly, you are interested in particle currents, not fluences.

A couple of other notes regarding your input:
- PRESICIOn default sets particle transport threshold at 100 keV, but you start the antiprotons at 10 keV. You may want to lower the transport thresholds for the relevant particles using PART-THR card, like you did for the alphas.
- Using two adjacent RPPs in geometry may lead to a problem because the points exactly on the boundary between them technically belong to both regions. You can avoid a potential problem by defining your regions using RPP and XYP, or by subtracting one RPP from another one.
- In the future, please try sending your input file as an attachment, instead of the text in the message body. It is easier to quickly open it in flair that way.

Best regards,

----- Original Message -----
From: "Sebastian Kalista" <>
To: "FLUKA Discussion List" <>
Sent: Tuesday, February 21, 2017 4:37:11 AM
Subject: [fluka-discuss]: Antiproton secondaries, Energy distribution

Dear FLUKA users and experts,

I am currently working on an antiproton annihilation experiment and I am trying to simulate the experimental setup. For my first few steps I chose an easy set-up and started implementing it in FLAIR. To be exact antiprotons impinging on an aluminum foil.

I defined two regions TARGET and TARGET2 (both thin aluminum foils touching each other in the x-y-plane). I am now interested in two plots:

1. The number of the produced secondaries and their energy. For example number of Pions on the y-axis and energy on the x-axis.
2. The angle between secondaries and the incoming beam direction. Number of lets say Pions again on the y-axis and on the x-axis the angle.

Here is my current input file:

Antiproton on foil
* Set the defaults for precision simulations
* Antiprotonen
* Define the beam position
    0 0
* Black body
SPH blkbody 0.0 0.0 0.0 100000.0
* Void sphere
SPH void 0.0 0.0 0.0 10000.0
* Cylindrical target
RPP target -10.0 10.0 -10.0 10.0 -0.5E-03 0.5E-03
* Cylindrical target
RPP target1 -10.0 10.0 -10.0 10.0 0.5E-03 1E-03
* Black hole
BLKBODY 5 +blkbody -void
* Void around
VOID 5 +void -target-target1
* Target
TARGET 5 +target
TARGET2 5 +target1
* ..+....1....+....2....+....3....+....4....+....5....+....6....+....7..
USRBDX 98. 4-HELIUM -21. TARGET TARGET2 100.blabla
USRBDX 100. 1E-05 700. &
USRBIN 10. APROTON -50. 20.0 20.0 20.0Enedepap
USRBIN -20.0 -20.0 -20.0 100. 100. 100. &
USRBIN 10. PIONS+- -50. 20.0 20.0 20.0Enedeppi
USRBIN -20.0 -20.0 -20.0 100. 100. 100. &
USRBIN 10. PROTON -50. 20.0 20.0 20.0Enedepp
USRBIN -20.0 -20.0 -20.0 100. 100. 100. &
USRBIN 10. DEUTERON -50. 20.0 20.0 20.0Enedepd
USRBIN -20.0 -20.0 -20.0 100. 100. 100. &
USRBIN 10. 4-HELIUM -50. 20.0 20.0 20.0Enedephe
USRBIN -20.0 -20.0 -20.0 100. 100. 100. &
* Set the random number seed
* Set the number of primary histories to be simulated in the run
START 10000.

So for the first plot i tried to use an USRBDX detector. But i am not quite sure what the y-axis tells me and how i can convert it from fluence to total particle number.

Thank you guys in advance for your help

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Received on Tue Feb 21 2017 - 16:33:59 CET

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