FLUKA

Report
New developments in FLUKA
Paola Sala
INFN Milano
On behalf of the FLUKA collaboration
≈ 50 members from several institutions around the world
Varenna, June 14th 2012
http://www.fluka.org
A glimpse of latest developments and
applications
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FLUKA is a general purpose tool for calculations of particle
transport and interactions with matter (all hadrons, ions, EM)
FLUKA applications range from LHC or cosmic energies down to
hadron-therapy (A. Mairani’s talk) and microdosimetry
Standard tool at CERN for beam-machine interactions and
radioprotection
A long and constant development of nuclear interaction models
that benefits to a wide range of applications
Without forgetting EM and particle transport
In this talk some news on
Hadronic interactions in the few GeV energy range and neutrinos
Interactions of  particles below 150 MeV/A
Improvements in the latest stages of nuclear reactions with
examples
Very high energy : examples of LHC applications
June 14th, 2012
Paola Sala, Varenna2012
http://www.fluka.org
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Hadron interactions in FLUKA: an integrated
ensemble
h-h
DPM + quark chain
hadronization
h-A
PEANUT
A-A
Glauber-Gribov multiple
collisions
DPMJET3
Resonance production
and decay
G-INC
Preequilibrium (Exciton)
Elastic, ch.exc.
Evaporation/Fragmentation or
Fermi Break-up
 deexcitation
Neutrino
June 14th, 2012
rQMD-2.4
BME
Muon photonuc
Photonuclear
Em-dissociation
Paola Sala, Varenna2012
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DualPartonModel at its lower limit
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Strong experimental effort is ongoing on particle
production from beams in the few to tens of GeV
range
Important for neutrino beams and interactions
Challenging: too high energy for resonance
formation, too low for quark gluon based models
Fluka high energy hadron-hadron interaction model
– DPM-: chain production and chain hadronization
Strong mass effects for low energy chains
“standard” hadronization outside its validity region
NEW: gradual transition of low energies chains to
“phase space explosion” constrained in pT , including
baryons, mesons, resonances.
June 14th, 2012
Paola Sala, Varenna2012
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Neutrino interactions (ICARUS..):
Fluka has its own neutrino interaction generator, including QE, Resonance, DIS
DIS uses the same chain hadronization as DPM
Embedded in the FLUKA nuclear environment (PEANUT)
New low-mass chain treatment-> improvements in the RES-DIS transition
μ+p ->μ- +p++
June 14th, 2012
Paola Sala, Varenna2012
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Pion production close to DPM thr.
Pion production from proton interactions on Be at 12.3 GeV
Emitted pion spectra at different angles in the range 300 - 600
Dots: data (BNL910 expt.), histograms : Fluka
+
-
June 14th, 2012
Paola Sala, Varenna2012
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Pion production close to DPM thr.
Pion production from proton interactions on Be at 17.5 GeV
Emitted pion spectra at different angles in the range 00 - 200
Dots: data (BNL910 expt.), histograms : Fluka
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+
June 14th, 2012
Paola Sala, Varenna2012
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-induced reactions, -emitters
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Fragmentation tail in hadrontherapy beams
Radiation damage to electronics
Production of residual nuclei: On heavy targets, interactions of
secondary ’s can produce dangerous radioisotopes, for instance:
 (, Bi )  At : chemically reactive (halogen)  and + emitters.
Eg, 21085At has a mean life of 8.1 h, 5.6 MeV  decay and  decay
to 21084Po
 (, Pb )  Po ...well known “problematic” -emitters
Some of these isotopes have exemption limits 3-4 order of
magnitudes smaller than most other radioisotopes commonly
produced at accelerators
New in FLUKA:  - induced reactions at low energy (E < 150 MeV/A)
through the BME model
At higher energies: already handled through the rQMD-2.4 and
DPMJET-3 models
June 14th, 2012
Paola Sala, Varenna2012
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FLUKA: the BME Model for nucleus – nucleus
interactions below 150 MeV/n
The BME ( Boltzmann Master Equation) in FLUKA
It works for Aproj,Atarg 4, E  150 MeV/A
1. COMPLETE FUSION
2. PERIPHERAL COLLISION
three body mechanism
Fragment(s) : pre-equilibrium
de-excitation according to the
BME theory (where available)
or to the PEANUT exciton model
evaporation/fission/fragmentation/
gamma de-excitation, same as for
hadron-nucleus interactions
with
incomplete fusion
one nucleon break-up and possibly
transfer (at high b)
pickup/stripping (for asymmetric
systems at low b)
The kinematics is suggested by
break-up studies.
BME : E. Gadioli group in Milano
June 14th, 2012
Paola Sala, Varenna2012
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BME in FLUKA : (,xn) examples
Excitation functions for the production of radioisotopes from 
interactions on Au (left) and Pb ( right) (Data: CSISRS, NNDC)
June 14th, 2012
Paola Sala, Varenna2012
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Gamma De-excitation in Fluka
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At the end of evaporation : cascade of  transitions
At high excitation: assume continuous level density
and statistical emission:
 f (U f )
P( E )dE 
f ( E , L)

L
i (U i )
f = strength from single
particle estimate (c)+ hindrance (F)
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L= multipole order
=level density at
excitation energy. U
f (E , L)  cL FL ( A)E(2L1)
At low excitation: through discrete levels
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Tabulated experimental levels (partial coverage)
Rotational approximation outside tabulations
See A. Ferrari et al., Z. Phys C 71, 75 (1996)
June 14th, 2012
Paola Sala, Varenna2012
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Ongoing developments for ’s:
Extended database of known levels and transitions taken
from RIPL-3 (IAEA)
 Discrete level treatment extended to evaporation stage
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Already inserted in the released FLUKA2011.2
Photon angular distribution according to multipolarity and spin
( effort to estimate residual spin value and direction in
PEANUT, BME, rQMD)
 Account for discrete levels in BME (to be extended to rQMD
and DPMJET)
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Application : prompt photon for in-vivo hadron therapy
monitoring
June 14th, 2012
Paola Sala, Varenna2012
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Prompt photons: benchmarks I
Prompt photons
measured during
irradiation of water
and PMMA phantoms
with C ions.
Photon spectra
measured at 900 wrt
beam
Time-of-flight to
discriminate neutron
background
[figures and exp. data taken from F. Le Foulher et al IEEE TNS 57
(2009),E. Testa et al, NIMB 267 (2009) 993] and later revisions
Threshold at 2 MeV
to discriminate
prompt photons from
secondary photons,
bremsstrahlung etc.
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Results
Bragg peak position
95 MeV/u
Counts/ion vs
position along
the phantom
(mm)
310 MeV/u
Exp. Energy/tof
Distribution and
Window
Scatter plot and exp.
data taken from F. Le
Foulher et al IEEE TNS
57 (2009) and later
revisions
Bckg subtraction
from data to
equalize the
bckg.level before
the target
Blue: fluka
Red: data
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Photon yields by 160 MeV p in PMMA
Absolute comparison
Energy spectrum of “photons” after background subtraction (collimator open –
collimator closed) for 160 MeV p on PMMA. FLUKA red line, data black line
(J.Smeets et al., ENVISION WP3)
June 14th, 2012
Paola Sala, Varenna2012
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Spin-parity in Fermi-Break-up
For A<16, evaporation is substituted by Fermi break-up
In cases where spin and parity of the residual nucleus are known,
conservation laws, constraints on available configurations and centrifugal
barrier (if L=0 is forbidden), are enforced in the fragment production
Straightforward example : photonuclear reaction in the GDR region
Effect : residual nuclei production
Application: background from induced activity in underground experiments
12C + in GDR
J = 1 3 and  + 8Be
impossible in L=0
Factor 3 on 11C
production
June 14th, 2012
Paola Sala, Varenna2012
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Examples at LHC
June 14th, 2012
Paola Sala, Varenna2012
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Application at 3.5+3.5 TeV
(2.6 1010 MeV eq. in lab)
BLM response along triplet right of IR5
• BLM dose per collision assuming CMS luminosity measurement and 73.5 mb
proton-proton cross-section (from TOTEM)
• Discrepancy possibly due to geometry model (e.g. interconnections are not
modeled
in detail)
June 14th, 2012
Paola Sala, Varenna2012
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ElectroMagnetic dissociation at LHC
Electromagnetic dissociation: sEM increasingly large with (target)
Z’s and energy. Already relevant for few GeV/n ions on heavy
targets (sEM ~ 1 b vs snucl ~ 5 b for 1 GeV/n Fe on Pb)
d
1   n A1 ()  n A2 ()  Z12
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Total electromagnetic and nuclear cross
sections (barn) for Pb-Pb interactions at
the energy sNN = 2.76 TeV
Reaction
FLUKA
ALICE (arXiv:1203.2436v1 [nucl-ex].)
Single EMD + nuclear
199
194.6 ± 0.3 stat +14.1/–12.1 syst
nuclear
7.67
7.5 ± 0.1 stat +0.6/–0.5 syst
Single EMD
191.3
187.2 ± 0.2 stat +13.8/–12.0 syst
Paola Sala, HSS066
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Work partially supported by the ENVISION and PARTNERS
European programs
June 14th, 2012
Paola Sala, Varenna2012
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