abriefintroductiontofluka - tum physikdepartment (indico)

SFB & GSSI Geant4 schoolApril 16-20, 2018@ Garching

A brief introduction to FLUKAwith focus on cosmogenic muons

Anton EmplUniversity of Houstonwith Béla Majorovits, MPI für Physik - MünchenMINIDEX

April 20, 2018

fluka introduction

taken from FLUKA beginner’s course material Anton Empl, UH - SFB/GSSI Geant4 school - April’18 1

fluka outline

Motivation This presentation is obviously not a lecture, rather it isintended as advertisement.

Why a second tool Simulation programs, like Geant4 or FLUKA , are verypowerful tools. They are used to study rather complexsystems and expected to predict physics correctly in regimeswhere no experimental data exists. A second opinion can bereally helpful.

current FLUKA version FLUKA2011.2x released on: February 8th 2018- the next release is expected for later this year

Focus A good fraction of my simulation work has been beenconcerned with low background experiments wherecosmogenic muons and muon-induced neutrons areimportant.

FLAIR advanced user friendly interface for FLUKA

Anton Empl, UH - SFB/GSSI Geant4 school - April’18 2

fluka monte carlo method

Geant4 and FLUKA areMonte Carlo simulation toolsHow did the name come about?

Enrico Fermi is to credit for first using a similar approach during the early1930’s, hand cranked though and not published

John von Neumann and Stanislaw Ulamformulated, used and named the approachMonte Carlo.

In 1946 this was all secret and classified and thework required a code name. Von Neumannpicked Monte Carlo because the uncle of S.Ulam would borrow and lose money in theCasino at Monaco.

In context of neutron diffusion problem.

Wikipedia - S. UlamAnton Empl, UH - SFB/GSSI Geant4 school - April’18 3

fluka introduction


fluka applications


fluka a collaboration


fluka applications


fluka one complex example



Primary Collimators IR7


fluka differences to geant4

Computer program FLUKA is written in FORTRAN and is available underLinux and, starting with the current release, under macOS.Supported compilers: recent gfortran (and still g77)

License Users have to register through the FLUKA website

Source code Is available under special conditions only

Physics models FLUKA is not a toolkit. The FLUKA physics models are fullyintegrated and the user can not change the physics.

Input file The user interacts with FLUKA via an ASCII input file. Forstandard situations no coding is required and scoring/outputis built in.

Geometry Combinatorial Geometry


fluka license


fluka resources

the FLUKA manual

www.fluka.org

Beginner’s course One can find the material of previous FLUKA courses onthe FLUKA website. The lectures and instructionis/input filesto perform the exercises are available.

Exercise 1 Input file and geometry will be discussed as an example.Getting Fluka and installing FLUKA are described in the second lecture of

the beginner’s course

Mailing list Provides (fast) response from the developers in case ofquestions.

Discussion archive Is the moderated collection of questions/answers inregards to FLUKA simulations and physics from the mailinglist since 2001.


fluka a simple example

Beginner Course: exercise 1 (almost) Anton Empl, UH - SFB/GSSI Geant4 school - April’18 14

fluka flair

author: Vasilis Vlachoudis

FLUKA advanced user interfaceFLAIR provides the user with a simple way to— build the input file— construct/debug the geometry— compile and execute FLUKA - single and batch runs— process and inspect standard output information— lowers the threshold for users to get started using FLUKA

uses a python API

EffectThe availability of FLAIR is attracting new users.

— In my personal opinion, the main benefits of FLAIR aregiven by helping to prepare the FLUKA input file and toconstruct/debug the geometry.


fluka flair


fluka advanced user interface


fluka flair


fluka geometry editor/viewer


fluka debugging the geometry


fluka cosmogenic muons

Cosmogenic muons

Muon-induced backgrounds at LNGS: Borexino and Darkside(low Z target material, deep - Eµ,kin approx 283GeV)

— MINIDEX(high Z target materials, shallow - Eµ,kin approx 10GeV)

also used to possibly investigate the interior of asteroidsand to look for Oil


underground experiments borexino

The Borexino inner detector at filling with liquid scintillator and the experiment as it was

implemented in FLUKA. Borexino contains approximately 300 t of liquid scintillator in a 8.5mdiameter inner nylon vessel.

Over 80% of the generated cosmogenic neutrons are recorded.

“Cosmogenic Backgrounds in Borexino at 3800 m water-equivalent depth”,JCAP 1308 (2013) 049 - arXiv:1304.7381

FLUKA visualization with FLAIR


fluka neutron capture multiplicity

LRT 2015, Seattle


fluka radioactive isotope production

LRT 2015, Seattle


fluka neutron yield

LRT 2015, Seattle


fluka minidex

MINIDEXMuon-Induced Neutron Indirect Detection ExperimentBéla Majorovits at MPI

Scintillator signals from above and below a lead target are used to tag muons. The capture of

neutrons on hydrogen (in a water volume surrounding 2 high-purity germanium detectors) with

the emission of a 2.223MeV gamma is used to identify neutrons.

I will not report on the final measurement results.


fluka minidex

MINIDEX is located in the Untergrund Labor at the University of Tübingen.The FLUKA implemented geometry is superimposed on a technical designdrawing for comparison.

A publication reporting on the muon-induced neutron measurement is underpreparation. Results for a Geant4 simulation making use of the MaGe framework willbe included. This is the PhD thesis work of Raphael Kneißl.


fluka detector setup

The MINIDEX detector setup.

left: 3D rendering of setup prepared with FLAIRright: Central cross sectional view of detector setup


fluka minidex at tübingen



Muon and muon-induced radiation field for MINIDEX

The simulation is started with GCR impinging on the earth atmosphere atapproximately 70 km altitude. The magnetic field is taken into account and a standard100 layer US atmosphere is implemented. left: model of earth, right: magnetic fieldeffect for different latitudes. — standard GCR tools provided with FLUKA



FLUKA predictions

left: Muon kinetic energy spectrum predicted at the surface (open red symbols), insidethe lab (yellow symbols) and at the surface for the muons which reach the lab (bluesymbols). right: Measured (red and black spectra) and predicted (yellow) energydeposition spectra for the TOP scintillator.



FLUKA simulation: the absolute predicted rates are within 20% of the experimentalfindings for both stopping and through-going muons.

Stopping muons inside the BOT scintillator (left) and the TOP scintillator. The peaks athigher energy show the energy deposition by the stopping muons. The peaks at lowerenergy are created by the coincident muon decay electrons or positrons. Measuredand FLUKA predicted spectra are superimposed.


conclusion

We are planing to offer a FLUKA beginners tutorial locally. The exact formatand time are not decided yet. However, participants are expected to be ableto install FLUKA, prepare a simple physics example and perform a successfulsimulation after the course.

In case of interest, please send email [email protected] or [email protected]

Thank you for your attention


abriefintroductiontofluka - tum physikdepartment (indico)

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