FLUKA radiation damage calculations for colliders like the ......FLUKA radiation damage calculations...

FLUKA radiation damage calculations for colliderslike the HL-LHC

A. Lechner, L. Esposito, F. Cerutti, A. Ferrari, G. Steele, N.V. Shettyon behalf of the FLUKA team (CERN)

in collaboration with

N. Mokhov (FNAL)

with valuable inut from

R. Bruce, B. Auchmann, A. Verweij, M. Sapinski, A. Priebe, T. Baer (CERN)

RESMM’14

May 13th, 2014

A. Lechner (CERN) May 13th , 2014 1 / 25

Introduction

Contents

1 Introduction

2 FLUKA and DPA: a brief recap

3 HL-LHC (inner triplet and D1 in IR1/5): proton collision debris

4 HL-LHC (DS next to IR2): ion collision debris

5 HL-LHC/LIU (IR2/IR8): fast failures during injection

6 Summary


Introduction

Radiation transport in matter ... stochastic in nature


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

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

• Dose and DPA calculations for the HL-LHC


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 cm

2 active vol.)

Losses induced by beam wire scanner ([email protected] 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.


Introduction

Validation of dose calculations for TeV proton losses (operational beam losses)

Losses induced by chamber fragments (p@4 TeV)

- Beam losses due to proton interactions with micrometer-fragmentsseparated from MKI vacuum chambers (caused several beam dumps)

- By analysing BLM pattern, FLUKA studies allowed to determine dustparticle locations around MKIs (=injection kickers)

BLM

Q5

MKI

Q5

MKI

MKI

Photo by M. Barnes

Photo by M. Barnes

10-2

10-1

100

101

3170 3180 3190 3200 3210

DB

LM

/D

BL

M,m

ax

s (m)

FLUKAMeasurement

MK

I-D

MK

I-C

MK

I-B

MK

I-A

D2Q4

Relative comparison!

Number of inelastic proton-dust particle interactions not known.

Losses induced by dust particles in arcs (p@4 TeV)

- Proton interactions with dust particles in the LHC arcs (insulationdebris etc.)

Beam screen interior, photo by C. Garion.

10-3

10-2

10-1

100

101

7490 7500 7510 7520 7530

DB

LM

/D

BL

M,m

ax

s (m)

FLUKAMeasurement

Relative comparison!

Number of inelastic proton-dust particle interactions not known.


Introduction

Involvement of CERN FLUKA team in collider upgrade/design studies

HL-LHC:

Direct involvement in different Work Packages:

• WP5 (Collimation)TCLs, DS collimators, exp. background etc.

• WP10 (Energy Deposition & Absorber)Joint Studies FLUKA (CERN) andMARS (N. Mokhov, Fermilab)IR1/5 triplet, matching section magnets etc.

• WP14 (Beam Transfer & Kickers)injection and extraction absorbers

Close collaboration with many other WPs.

FCC (Future Circular Collider):

Involvement in first design studies (starting rightnow), e.g. concerning final focus, etc.


FLUKA and DPA: a brief recap

Contents

1 Introduction





6 Summary




• DPA can be induced by all particles produced in the hadronic cascade• displacement damage related to energy transfers to atomic nuclei (restricted NIEL)• see also F. Cerutti’s talk at RESMM’13 for some more details

Charged particles (incl.heavy ions)

During transport Restricted non-ionizing energy loss (NIEL) calculated alongparticle step (using Lindhard partition function and energydependent displacement efficiency κ(T ))

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 charged

particles

1For ≤20 MeV neutron transport, FLUKA uses multi-group approach (group-to-groupscattering probabilities from NJOY).


HL-LHC (inner triplet and D1 in IR1/5): proton collision debris

Contents

1 Introduction





6 Summary



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



Dose in coils of triplet quadrupoles, correctors and D1 (3000 fb−1)

0

10

20

30

40

50

20 30 40 50 60 70 80

Peak

dos

e (M

Gy)

Distance to IP1 (m)

Q1 Q2a Q2b Q3 D1

MC

BX

MC

BX

MC

BX

Dose in Q2a coils, magnet front (MGy)

-10 -5 0 5 10

x (cm)

-10

-5

0

5

10

y (

cm)

5

10

15

20

25

30

Dose in Q2b coils, magnet front (MGy)

-10 -5 0 5 10

x (cm)

-10

-5

0

5

10

y (

cm)

5

10

15

20

25

30

Dose in Q3a coils, magnet front (MGy)

-10 -5 0 5 10

x (cm)

-10

-5

0

5

10

y (

cm)

5

10

15

20

25

30

Dose in Q3b coils, magnet end (MGy)

-10 -5 0 5 10

x (cm)

-10

-5

0

5

10

y (

cm)

5

10

15

20

25

30

0

5

10

15

20

20 30 40 50 60 70 80

y (

mm

)

Distance to IP1 (m)

Q1a Q1b Q2a Q2b Q3a Q3b D1

Co

rr

Co

rr

Co

rr

See also N. Mokhov’spresentation on MARSresults

Optics: round

β∗ 15 cm

θ× 590µrad

×-plane vertical∆‖ 1.5 mm

- p–p inelasticcross-section: 85 mb

- collisions simulated bymeans of DPMJET-III

- details of INERMET(W-alloy) shielding(transverse shape,gaps in interconnects)can change dosevalues by few 10%



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: ∼1.8×10−4DPA 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



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 ofDPA calculationsin next pages



Fluence spectra in Q1 coils

10-8

10-7

10-6

10-5

10-4

10-3

10-2

10-1

100

10-1410-1210-10 10-8 10-6 10-4 10-2 100 102 104

Flue

nce

spec

trum

/pp

coll

(dN

/dlo

gE/c

m2 )

Energy (GeV)

Neutrons

-10

-5

0

5

10

-10 -5 0 5 10

y (c

m)

x (cm)

Q1

x

10-910-810-710-610-510-410-310-210-1100

10-4 10-3 10-2 10-1 100 101 102 103 104

Flue

nce

spec

trum

/pp

coll

(dN

/dlo

gE/c

m2 )

Energy (GeV)

e-/e+ transp. cut: 0.5 MeV


10-11

10-10

10-9

10-8

10-7

10-6

10-5

10-4

10-3

10-2

10-6

10-4

10-2

100

102

104

Flu

ence

sp

ectr

um

/pp

co

ll (

dN

/dlo

gE

/cm

2)

Energy (GeV)

Charged hadronsProtons

Charged pionsCharged kaons

Particle spectra:

- in second Q1 module- longitudinally and radially

averaged over inner cable ofupper coils

- expressed per pp collision- expressed as lethargy

Transp.cut:

photons 100 keV

e−/e+ 500 keV

neutrons 10−5 eV

ions 0.25 keV/nucl

other 1 keV



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 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

(500 keV)

0.6% Pions above transport threshold (>1 keV)

HL-LHC (DS next to IR2): ion collision debris

Contents

1 Introduction





6 Summary




• ALICE performance goal for ion operation after2018 ([email protected]/u) [1]:

◦ instantaneous luminosity of 6×1027 cm−2s−1(= 6 × design luminosity)

◦ integrated luminosity of 10 nb−1

• Secondary ion beams due to electromagneticinteractions (see [2] for details):

◦ e.g. bound-free pair production (BFPP), witha cross section of ∼281 b:208Pb82+ + 208Pb82+ →208Pb82+ + 208Pb81+ + e+

◦ changed magnetic rigidity with respect toprimary ion beam

◦ localised losses (and heat deposition) in DSmagnets next to IR2 due to higher dispersion

• To mitigate risk of quenches, alternative layoutwith DS collimator + 11T dipoles is under study

◦ not covered in this presentation

MB.B10R2

Losses concentrated in thelast ~4 m of the magnetBeam

FLUKA simulations are based on SixTrackimpact distributions from R. Bruce [2]

[1] J. Jowett and M. Schaumann, “Dispersion SuppressorCollimators for Heavy-Ion Operation”, Collimation Review 2013.[2] R. Bruce et al., PhysRevSTAB 12, 071002, 2009.



Peak power density (6×1027 cm−2s−1), dose and DPA (10 nb−1) in MB.B10R2 coils

Power density (mW/cm3) in MB.B10R2 coils

-14 -12 -10 -8 -6 -4

x (m)

-4

-2

0

2

4

y (c

m)

10-1

100

101

102

0

20

40

60

80

100

375 376 377 378 379 0

0.1

0.2

0.3

0.4

0.5

0.6

Pea

k p

ow

er d

ensi

ty (

mW

/cm

3)

Loss

den

sity

per

BF

PP

(1/m

)

Distance to IP2 (m)

MB.B10R2

Beam 1

Peak powerLoss distribution

0

5

10

15

20

25

375 376 377 378 379

Peak

dos

e (M

Gy)

0

0.05

0.1

0.15

0.2

0.25

0.3

375 376 377 378 379

Peak

DPA

(10

-4)

Distance to IP2 (m)

Main DPA contributions from ions (i.e. recoils) and electronsabove transport threshold as well as neutrons


Fluence spectra in MB coils

10-5

10-4

10-3

10-2

10-1

100

101

102

103

10-14

10-12

10-10

10-8

10-6

10-4

10-2

100

102

104

Flu

ence

sp

ectr

um

/BF

PP

(d

N/d

log

E/c

m2)

Energy (GeV)

Neutrons

-8

-6

-4

-2

0

2

4

6

8

-8 -6 -4 -2 0 2 4 6 8

y (

cm)

x (cm)

MB.B10R2

x

10-8

10-6

10-4

10-2

100

102

104

10-4

10-3

10-2

10-1

100

101

102

103

104

Flu

ence

sp

ectr

um

/BF

PP

(d

N/d

log

E/c

m2)

Energy (GeV)

e-/e

+ transp. cut: 0.5 MeV


10-6

10-5

10-4

10-3

10-2

10-1

100

101

102

10-6 10-4 10-2 100 102 104

Flue

nce

spec

trum

/BFP

P (d

N/d

logE

/cm

2 )

Energy (GeV)

Charged hadronsProtons

Charged pions

Particle spectra:

- radially averaged over innercable of most exposed coils

- longitudinally averaged over∼ 180 cm (around peak)

- expressed per bound-free pairproduction

- expressed as lethargy

Transp.cut:

photons 100 keV

e−/e+ 500 keV

neutrons 10−5 eV

ions 0.25 keV/nucl

other 1 keV


HL-LHC/LIU (IR2/IR8): fast failures during injection

Contents

1 Introduction





6 Summary




• HL-LHC/LIU injection beam parameters(p@450GeV, 25 nsec, BCMS beams):

◦ �n = 1.37µm rad◦ 288 × (2.0×1011) = 5.8×1013 prot. per inj.→ beam brightness significantly higher thanfor nominal LHC

• Injection kicker (MKI) malfunctions◦ Can lead to fast single-turn failures (


Energy density estimates for previous injection failures

10-1

100

101

-70 -65 -60 -55 -50 -45 -40 -35 -30 -25 -20

Peak

ene

rgy

dens

ity (

J/cm

3 )

Distance from IP2 (m)

D1Q3

Q2bQ2a

Q1

beam direction

scoring mesh:∆r≈2 mm, ∆φ=2°, ∆z=10 cm

Damage limit for Nb-Ti cables (B. Auchmann, A. Verweij):

• Fast and localized thermal expansion may give rise tothermal shockwave in coils

◦ Potentially more damaging than slow heating up tosame temperature (due to local shear)

◦ Hence, design goal for protection devices:- peak temperature in coils due to fast beam losses

should be limited to 80 K- gives a limiting energy density of 54 J/cm3

(integration of heat capacity)

• One of the worst inj. failures in Run I◦ MKI erratic on 28/07/2011◦ 176 circulating bunches deflected with

12.5% of nominal MKI strength◦ most bunches were grazing on TDI◦ D1 and triplet quenched◦ figure left: FLUKA prediction of peak

energy density in coils

→ were safe in the past→ failure scenarios to be reevaluated

for HL-LHC (higher beambrightness!)

Energy density (J/cm3)

-15 -10 -5 0 5 10 15

x (cm)

-15

-10

-5

0

5

10

15

y (c

m)

10-3

10-2

10-1

100

101


Summary

Contents

1 Introduction





6 Summary


Summary

Summary

• HL-LHC proton collision debris impacting on triplet (IR1/5):◦ FLUKA predicts max. DPA of ∼1.8×10−4 in Q1 coils for 3000 fm−1◦ Dominant contribution due to neutrons

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FLUKA radiation damage calculations for colliders like the ......FLUKA radiation damage calculations...

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