Post on 24-Feb-2021
DPA calculations with FLUKA
A. Lechner, L. Esposito, P. Garcia Ortega, F. Cerutti, A. Ferrari, E. Skordison behalf of the FLUKA team (CERN)
with valuable input from
R. Bruce, P.D. Hermes, S. Redaelli (CERN) and N. Mokhov (FNAL)
2nd EuCARD2 ColMat-HDED annual meeting
Dec 5th, 2014
A. Lechner (CERN) Dec 5th , 2014 1 / 20
Introduction
Contents
1 Introduction
2 FLUKA and DPA
3 DPA in LHC primary collimators (IR7) due to halo particles (preliminary)
4 DPA in HL-LHC inner triplet magnets (IR1/5) due to proton collision debris
5 Summary
A. Lechner (CERN) Dec 5th , 2014 2 / 20
Introduction
Radiation transport in matter ... stochastic in nature
A. Lechner (CERN) Dec 5th , 2014 3 / 20
Introduction
LHC beam-machine interaction studies: from beam losses to secondary shower description
FLUKA is regularly used at CERN to perform LHCbeam-machine interaction simulations in the context of
machine protection
collimation
BLM threshold settings
high-luminosity upgrade
design studies for new devices (absorbers etc.)
radiation to electronics (R2E project)
activation studies
background to experiments
...
Types of LHC beam losses simulated withFLUKA – both, normal and accidental ...
luminosity production in experiments
halo collimation
injection and extraction failures
residual gas in vacuum chamber
dust particles falling into beam
...
Main focus of this presentation
• DPA calculations with FLUKA (incl. examples)
A. Lechner (CERN) Dec 5th , 2014 4 / 20
Introduction
Validation of dose calculations for TeV proton losses (controlled beam loss experiments)
• FLUKA is based, as far as possible, on well bench-marked microscopic models
• However, first years of LHC operation also allowed tovalidate FLUKA dose predictions against Beam LossMonitors (BLMs) measurements
• BLMs measure dose from secondary showers inmachine elements (magnets, collimators, etc.)
• Several thousand BLMs are installed around the ring
(ICs, filled with N2 gas, about 1500 cm2 active vol.)
Losses induced by beam wire scanner (p@3.5 TeV)
- Quench test 2010 in LHC IR4 (M. Sapinski et al.)
- Wire scans: showers due to collision products registered in BLMsinstalled on downstream magnets (∼35 from wire scanner)
10-1
100
101
10115 10120 10125 10130 10135
DB
LM
/N
i (pG
y)
s (m)
FLUKAMeasurement
Absolute comparison!
Ni =number of inelastic proton-wire interactions (derived analytically)
Direct losses on MQ beam screen† (p@4 TeV)
- Quench test 2013 in arc sector 56 (A. Priebe et al.)
- Proton losses on beam screen (over ∼1.5 m) by means of orbitbump/beam excitation, dose measured by BLMs outside of MQcryostat
10-1
100
101
16172 16176 16180
DB
LM
/N
p (
pGy)
s (m)
FLUKAMeasurement
Absolute comparison! (Np=number of lost protons (measured)
†FLUKA simulations based on MAD-X loss distribution from V. Chetvertkova et al.
A. Lechner (CERN) Dec 5th , 2014 5 / 20
FLUKA and DPA
Contents
1 Introduction
2 FLUKA and DPA
3 DPA in LHC primary collimators (IR7) due to halo particles (preliminary)
4 DPA in HL-LHC inner triplet magnets (IR1/5) due to proton collision debris
5 Summary
A. Lechner (CERN) Dec 5th , 2014 6 / 20
FLUKA and DPA
FLUKA and DPA in a nutshell
• DPA can be induced by all particles produced in the hadronic cascade
• displacement damage related to energy transfers to atomic nuclei
Charged particles (incl.heavy ions)
During transport DPA based on non-ionizing energy loss (NIEL)along particle step (restricted above damage thresh-old Eth), using Lindhard partition function ζ(T )and energy dependent displacement efficiency κ(T )
Figures: stopping powers for oxygen ions in silicon (left), silver ions in gold(right)
A. Lechner (CERN) Dec 5th , 2014 7 / 20
FLUKA and DPA
FLUKA and DPA in a nutshell
continued from previous page:
Charged particles (incl.heavy ions)
Particle falls belowtransport threshold
Nuclear stopping power integrated (using Lindhard partitionfunction)
Elastic and inelastic en-counters
Recoils and secondary charged particles explicitly produced iftheir energy lies above transport threshold (i.e. they becomea projectile), otherwise they are treated as below threhold.
Neutrons
≤20 MeV1 DPA is based on (un)restricted NIEL as provided by NJOY
> 20 MeV recoils: same as for elastic and inelastic encounters of chargedparticles
1For ≤20 MeV neutron transport, FLUKA uses multi-group approach (group-to-groupscattering probabilities from NJOY).
A. Lechner (CERN) Dec 5th , 2014 8 / 20
DPA in LHC primary collimators (IR7) due to halo particles (preliminary)
Contents
1 Introduction
2 FLUKA and DPA
3 DPA in LHC primary collimators (IR7) due to halo particles (preliminary)
4 DPA in HL-LHC inner triplet magnets (IR1/5) due to proton collision debris
5 Summary
A. Lechner (CERN) Dec 5th , 2014 9 / 20
DPA in LHC primary collimators (IR7) due to halo particles (preliminary)
Estimating DPA in LHC primary collimators (made of AC150)
• Two step simulation:
◦ Spatial distribution of inelastic proton-nucleuscollisions in collimators is derived by means ofmulti-turn tracking simulations (usingFLUKA-Sixtrack coupling, in collaborationwith LHC collimation team)
◦ Starting from this loss distribution, the DPAdistribution is calculated in detailed (low-cut)FLUKA shower calculations in jaw ofTCP.C6L7
• Note:
◦ By starting from the spatial distribution ofinelastic collisions, we neglect the DPAcontribution of primary protons before thecollision
• Assumptions for DPA calculations:
◦ beam energy of 7 TeV◦ horizontal losses only◦ annual beam losses of 1.15×1016 protons
→ corresponding to 40 fb−1 in 2012→ one needs to apply approximately a factor
100 to get an estimate for HL-LHC lumigoal (4000 fb−1)
A. Lechner (CERN) Dec 5th , 2014 10 / 20
DPA in LHC primary collimators (IR7) due to halo particles (preliminary)
Spatial distribution of inelastic proton collisions in the horizontal TCP
Tracking results from P. Garcia Ortega.
0.0·1005.0·10131.0·10141.5·10142.0·10142.5·10143.0·10143.5·1014
0 10 20 30 40 50 60
Inel
astic
col
lisio
ns (
1/cm
)
Distance from TCP front (cm)
Long. loss distr. in TCP.C6L7 (1.15x1016 protons lost)
External jaw (pos. x)Internal jaw (neg. x)
1015
1016
1017
1018
1019
0 50 100 150 200
Inel
astic
col
lisio
ns (
1/cm
)
Distance from TCP surface (µm)
Impact parameters in TCP.C6L7 (1.15x1016 protons lost)
External jaw (pos. x)Internal jaw (neg. x)
→ tracking simulations show unequal sharing of losses between TCP.C6L7 jaws (∼6:1)
A. Lechner (CERN) Dec 5th , 2014 11 / 20
DPA in LHC primary collimators (IR7) due to halo particles (preliminary)
DPA in TCP jaws (1.15×1016 protons lost) – preliminary results
TCP.C6L7
-10 -5 0 5 10
x (cm)
-4
-2
0
2
4
y (
cm)
0
1
2
3
4
0 10 20 30 40 50 60
Peak
DPA
(10
-3)
Distance from TCP front (cm)
TCP.C6L7 (1.15x1016 protons lost)
External jaw (pos. x)Internal jaw (neg. x)
DPA in TCP.C6L7, at peak (1.15x1016 protons lost)
-0.21 -0.2 -0.19 -0.18 -0.17 -0.16
x (cm)
-0.1
-0.05
0
0.05
0.1
y (c
m)
10-6
10-5
10-4
10-3
10-2DPA in TCP.C6L7, at peak (1.15x1016 protons lost)
0.16 0.17 0.18 0.19 0.2 0.21
x (cm)
-0.1
-0.05
0
0.05
0.1
y (c
m)
10-6
10-5
10-4
10-3
10-2Assumed Ethr (AC150): 35 eV
Max. DPA: ∼3×10−3
Transp.thre.
photons 100 keV
e−/e+ 500 keV
neutrons 10−5 eV
ions 0.25 keV/nucl
other 1 keV
A. Lechner (CERN) Dec 5th , 2014 12 / 20
DPA in LHC primary collimators (IR7) due to halo particles (preliminary)
Anatomy of DPA predictions in TCP jaw – preliminary results
0
1
2
3
4
0 10 20 30 40 50 60
Peak
DPA
(10
-3)
Distance from TCP front (cm)
TCP.C6L7, external jaw (1.15x1016 protons lost)
TotalIons (above thresh.)
Pions (above thresh.)Protons (above thresh.)
Electrons (above thresh.)Ions (below thresh.)
Neutrons (below thresh.)
Table below : contributionsto peak DPA at a depth of∼15 cm (for the TCP jawwith higher proton losses)
Peak DPA Type of
contribution: contribution:
62% Ions above transport threshold (>250 eV/nuc)
→ explicitly generated recoils
20% Pions above transport threshold (>1 keV)
5-6% Protons above transport threshold (>1 keV)
5-6% Ions below transport threshold (<250 eV/nuc)
→ non-transported recoils
6-7% Electrons above transport threshold (>500 keV)
<0.5% Others
Percentage values rounded; (statistical) error of contributions: ∼1%
A. Lechner (CERN) Dec 5th , 2014 13 / 20
DPA in HL-LHC inner triplet magnets (IR1/5) due to proton collision debris
Contents
1 Introduction
2 FLUKA and DPA
3 DPA in LHC primary collimators (IR7) due to halo particles (preliminary)
4 DPA in HL-LHC inner triplet magnets (IR1/5) due to proton collision debris
5 Summary
A. Lechner (CERN) Dec 5th , 2014 14 / 20
DPA in HL-LHC inner triplet magnets (IR1/5) due to proton collision debris
HL-LHC (inner triplet and D1 in IR1/5): FLUKA models and brief recap of layout
FLUKA model by L. Esposito (HL-LHC WP10)
20 30 40 50 60 70 80
Distance from IP (m)
LHCD1Q3Q2a Q2bQ1
MCBX
MCBX
MCBX
20 30 40 50 60 70 80
Distance from IP (m)
HL-LHC
D1Q3Q2a Q2bQ1
MCBX
MCBX
MCBX
CP
• HL performance goal for proton collisions@IR1/5:
◦ instantaneous luminosity of 5×1034 cm−2s−1
(= 5 × design luminosity)
◦ integrated luminosity of 3000 fb−1
(250 fb−1 per year)
HL-LHC: Q1,Q2,Q3→ Nb3Sn; D1, MCBX→ NbTi
A. Lechner (CERN) Dec 5th , 2014 15 / 20
DPA in HL-LHC inner triplet magnets (IR1/5) due to proton collision debris
Peak DPA and NIEL in coils of triplet quadrupoles, correctors and D1 (3000 fb−1)
0
10
20
30
40
50
20 30 40 50 60 70 80
Pea
k d
ose
(M
Gy
) Q1 Q2a Q2b Q3 D1
MC
BX
MC
BX
MC
BX
0
0.5
1
1.5
2
20 30 40 50 60 70 80
Pea
k D
PA
(10
-4)
0
0.5
1
1.5
20 30 40 50 60 70 80
Pea
k N
IEL
(1
01
2 G
eV/c
m3)
Distance to IP1 (m)
NIELRestricted NIEL
Assumed Ethr : 30 eV
Peak dose vs DPA:
• the latter has itsmaximum in Q1
• see particle fluenceson next page
Max. DPA: ∼1.8×10−4
DPA in Q1b coils , magnet end (10-4)
-10 -5 0 5 10
x (cm)
-10
-5
0
5
10
y (
cm)
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
DPA in Q3b coils , magnet end (10-4)
-10 -5 0 5 10
x (cm)
-10
-5
0
5
10
y (
cm)
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
A. Lechner (CERN) Dec 5th , 2014 16 / 20
DPA in HL-LHC inner triplet magnets (IR1/5) due to proton collision debris
Peak fluences in coils of triplet quadrupoles and D1 (3000 fb−1)
0.0·100
5.0·1017
1.0·1018
1.5·1018
2.0·1018
20 30 40 50 60 70 80
Peak
flu
ence
(1/
cm2 )
Q1 Q2a Q2b Q3 D1
PhotonsElectrons and positrons
0.0·100
5.0·1016
1.0·1017
1.5·1017
2.0·1017
20 30 40 50 60 70 80
Peak
flu
ence
(1/
cm2 )
Neutrons
0.0·100
4.0·1015
8.0·1015
1.2·1016
1.6·1016
20 30 40 50 60 70 80
Peak
flu
ence
(1/
cm2 )
Distance to IP1 (m)
ProtonsCharged hadrons
Neutrons in coils:
• max. fluence:1.8×1017 cm−2
• correlation peakneutron fluence –peak DPA
• see anatomy of DPAcalculations in nextpage
Transp.cut:
photons 100 keV
e−/e+ 500 keV
neutrons 10−5 eV
ions 0.25 keV/nucl
other 1 keV
A. Lechner (CERN) Dec 5th , 2014 17 / 20
DPA in HL-LHC inner triplet magnets (IR1/5) due to proton collision debris
Anatomy of DPA predictions in Q1
Contributions to DPAmaximum in Q1:
• Dominated by low-energy neutrons (forwhich FLUKA relies onNJOY-based values forDPA)
DPA in Q1b coils , magnet end (10-4)
-10 -5 0 5 10
x (cm)
-10
-5
0
5
10
y (
cm)
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
Peak DPA Type of
contribution: contribution:
70.7% Neutrons <20 MeV (NJOY)
24.4% Ions above transport threshold
(>250 eV/nucleon)
→ explicitly generated recoils (from neutron,proton, etc. interactions)
1.7% Protons above transport threshold (>1 keV)
1.6% Ions below transport threshold
(<250 eV/nucleon)
→ non-transported recoils
1.0% Electrons above transport threshold (>500 keV)
0.6% Pions above transport threshold (>1 keV)
<0.1% Others
Percentage values rounded; (statistical) error of contributions: few 0.1%
A. Lechner (CERN) Dec 5th , 2014 18 / 20
Summary
Contents
1 Introduction
2 FLUKA and DPA
3 DPA in LHC primary collimators (IR7) due to halo particles (preliminary)
4 DPA in HL-LHC inner triplet magnets (IR1/5) due to proton collision debris
5 Summary
A. Lechner (CERN) Dec 5th , 2014 19 / 20
Summary
Summary
• FLUKA offers a powerful way to calculate DPA for beam losses as encountered in theLHC operational environment or during beam tests
◦ In particular, allows to take into account the contribution of different particle types,including all particles produced in the particle shower development
• DPA estimates for horizontal primary collimator (preliminary):
◦ Simulation predicts a peak DPA of 3×10−3 for ∼40 fm−1 aka 1×1016 protons lost(or ∼0.3 for ∼4000 fm−1)
◦ Predominant contribution comes from recoils◦ However, present calculations still neglect contribution of primary protons before
they have an inelastic interaction
• DPA estimates for HL-LHC proton collision debris impacting on triplet magnets (IR1/5):
◦ FLUKA predicts max. DPA of ∼1.8×10−4 in Q1 coils for 3000 fm−1
◦ Dominant contribution due to neutrons <20 MeV (fluence up to 1.8×1017 cm−2)
A. Lechner (CERN) Dec 5th , 2014 20 / 20