LBNF MARS Modeling for Optimized Beamline · LBNF Long-Baseline Neutrino Facility LBNF MARS Modeling for Optimized Beamline Nikolai Mokhov Beam Optimization Review - FNAL October

Long-Baseline Neutrino FacilityLBNF

LBNF MARS Modeling for Optimized

Beamline

Nikolai Mokhov

Beam Optimization Review - FNAL

October 5-6, 2017

LBNF

Outline

10/05/2017 N. Mokhov | MARS Modeling for Beamline Optimization2

• Target Station

• Decay Channel and DS Window at Normal Operation

• Hadron Absorber at Normal Operation

• Beam Accidents

MARS LBNF Modeling Team:

N. Mokhov, I. Rakhno, D. Reitzner, S. Striganov and I. Tropin

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e95 = 20p mm-mrad, Np = 1.5×1014 pppBeam starts at z = -7.3 m from MC0, tilt = 0.101074

N. Mokhov | MARS Modeling for Beamline Optimization3

Scenarios & Beam Parameters

Scenario Ep (GeV) P (MW)Q (MJ)

s0 (mm)at MC0

b0 (m)at MC0

Cycle (s) × 1014

Normal 120 2.40 MW 1.7 110.8837 1.2 1.25 p/s

No-targetaccident*

120 2.88 MJ 2.4 221.03 1.2 1.5 ppp

Off-axis accident**

120 2.88 MJ 2.4 221.03 1.2 1.5 ppp

Normal 60 2.06 MW 1.7 55.44 0.7 2.14 p/s

*) On-axis

**) Beam points to absorber cooling water pipes

10/05/2017

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Target Station Configurations


Reference Design 2016 (RD)95-cm target, first 6 cm winged

2 NuMI-type horns, Air

Optimized Design 2017 (OD)198-cm target, first 12 cm winged,

3 optimized horns, Nitrogen

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Longer Target with Winged Fins at Upstream End


AirAl

Ti

He

Air

• In RD, 0.3% of beam miss targetentirely, giving 0.9-cm RMSon absorber (7 kW) addwinged fins on target upstream,6-cm (RD) and 12-cm (OD) long,to lower the peak EDEP

• In RD, 13% of proton beam do notparticipate in inelastic nuclearinteractions with target,experiencing just Coulomb andnuclear elastic scattering. Latterresults in a 4.9-cm RMS footprinton absorber(~300 kW) maketarget longer to lower pedestaland total power on absorber

Lines - analytical

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EDEP in Optimized Target/Horns (1)


Horn A Horn B Horn C

Energy Deposition (GeV/cm3/pot) vs longitudinal position (cm) in horn IC

0 50 100 150 200 250Position Along IC (cm)

0.0

0.5

1.0

1.5

2.0

2.5

ED

EP

(G

eV

/cm

3/p

) (

10

-3) Horn A IC

0 100 200 300 400Position Along IC (cm)

0.0

0.5

1.0

1.5

2.0

2.5

ED

EP

(G

eV

/cm

3/p

) (

10

-4) Horn B IC

0 50 100 150 200 2500 50 100 150 200 250Position Along IC (cm)

0.5

1.0

1.5

2.0

2.5

3.0

3.5

0.5

1.0

1.5

2.0

2.5

3.0

3.5

ED

EP

(G

eV

/cm

3/p

) (

10

-5) Horn C IC

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0 100 200 300 4000 100 200 300 400Position Along IC (cm)

2.1

2.2

2.3

2.4

2.5

2.6

2.7

2.8

2.9

2.1

2.2

2.3

2.4

2.5

2.6

2.7

2.8

2.9

ED

EP

Ratio

(12

0G

eV

/60G

eV

)

EDEP in Optimized Target/Horns (2)


Target tube: R=2.5cm, Ti

120GeV/60GeV Ratio

2.8 at peak

Horn B IC

Energy Deposition (GeV/cm3/pot)

-50 0 50 100 150 200 250-50 0 50 100 150 200 250Position Along Target Tube (cm)

0

1

2

3

4

5

0

1

2

3

4

5

ED

EP

(G

eV

/cm

3/p

) (

10

-3)

OD

~RD

OD/RD ~2 at peaks

Target tube

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EDEP (r) in US Decay Pipe Window: 120 vs 60 GeV


Transition from AlBeMet to Al (thinner bin)

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EDEP (r) in US DK Window: Nominal vs Accident


Transition from AlBeMet to Al (thinner bin)

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EDEP in Target Station Cooling Panels


Floor Max: 4.9×10-6 GeV/cm3/p

T-Blocks Max: 6.0×10-6 GeV/cm3/p

MARS EDEP mapsprovided to ANSYS team

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Target Station Model: Extracting EDEP for FEA


Extracting new MARS15 EDEP results for FEA analysisEspecially for the shielding block / module / stripline block studies

Shielding block binning

Diane

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EDEP in Target Station Components


Component REF OPT OPT/REF

Target/horns 153.70* 193.84* 1.26

Steel blocks/elements 769.9 1,004.04 1.30

Concrete blocks 0.201 0.132 0.66

Miscellaneous 27.7 39.71 1.43

Total 951.5 1,237.72 1.30

Power dissipation (kW)

*) REF (OPT): Baffle – 0.42 (0.41), target fins -23.55 (44.45), other target components –5.62 (11.26), Horn1 – 79.66 (A: 47.42), Horn2 – 41.76 (B: 60.66, C: 26.64), tanks – 2.69 (3.00) kW

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Double-Walled Steel Decay Pipe EDEP vs DK

Length: Optimized Design


350 kW total over entire length

ANSYS analysis was already performed using this as input

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DK Concrete EDEP in First 50cm Radially vs DK

Length


EDEP maps for entire DK including DS window are available in DUNE-doc-3303-v2 for ANSYS analysis

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EDEP and Star Density in DK Concrete for OD


For heat load & ground-water activation analysesat two longitudinal maxima and DK-averaged

Design limit

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EDEP (kW/m3) in DK DS Steel Window and Frame


3.42-mm Steel window 12.7-mm Steel frame

The peak value at the beam axis:RD: 190 kW/m3 in 3.42-mm stainless steel

90 kW/cm3 in 6.35-mm aluminumOD: 45 kW/m3 in 3.42-mm stainless steel

The peak value in 12.7-mm steel frame:RD: 26.5 kW/m3 at r=55 cmOD: 24.0 kW/m3 at r=55 cm

Peak OD/RD = 0.24

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EDEP in DK and DS Stainless Steel Window


Element REF OPT OPT/REF

Double-walled steel decay pipe

291 350 1.20

Concrete 158.3 189.3 1.20

SS window 0.08 0.06 0.75

Steel frame 2.7 2.8 1.04

Total 452.08 542.16 1.20

Power dissipation (kW)

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Hadron Absorber Configurations


Ref. Hadron Absorber (RHA)Non-uniformity, sculpting needed for RDwith a 30% safety margin

Uniform Hadron Abs (UHA)No sculpting, larger uniform masks, largercore blocks (60”->67”), 1/16” windows on maskblocks, simpler cooling and interface to hadronmonitor with a large safety margin for OD

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Proton and Energy Flux at Hadron Absorber

System at Normal Operation


Total Power: 854 kW (RD)and 436 kW (OD) OD/RD = 0.50Peak: OD/RD = 0.17

Lines - analytical

Eth=115 GeV

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Power Density (mW/cm3) in Hadron Absorber


RD Peak: 1.6 W/cm3 Peak: 0.24 W/cm3OD

Thanks to longer target and longer wings in OD, instantaneous (EDEP)and accumulated (DPA) peaks are down by a factor of 6.7 and totalheat load is down by a factor of 2 (for normal operation ) !

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EDEP (mW/cm3) in Reference Hadron Absorber

for RD and OD Beams


Axial Lateral

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EDEP in Reference Hadron Absorber Components (OD)


No Component kW

1 Spoiler 47.52

2 Masks 1-5 139.42

3 Al sculpted blocks 60.58

4 Al solid blocks 7.07

5 Steel core blocks 1-4 3.78

6 Steel shielding 134.5

7 Concrete 2.7

8 Miscellaneous 4.0

9 Total 400.0

1

23

4 5 6

66

6

7

7

7

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2.4-MW LBNF EDEP (kW) in OD vs RD


System RD OD OD/RD

Target Station 951.5 1,237.7 1.30

Decay Channel 452.1 542.2 1.20

Hadron Absorber 786.0 400 0.51

4-p Neutrino power 66 69 1.05

Misc: infrastructure,binding energy & sub-threshold ptcls

144.4 151.1 1.05

Total 2400 2400

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DS DK Window, Hadron Monitor and Spoiler


Peak EDEP (J/cm3) per 1.5×1014 ppp no-target accident:80 3.42-mm stainless steel window48 Hadron monitor (aluminum)235 Spoiler downstream (aluminum)

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DK DS Window at Beam Accident: EDEP & DT

per 1.5×1014 ppp


sx = sy = 2.4 mm at the missed targetentrance3.42-mm Stainless Steel windowT0 = 27 0CPeak DT = 23 0C

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Summary


• EDEP is well under control

• Hadron absorber system – EDEP, muon monitoring and radiological - is

under thorough optimization MARS calculations (uniform absorber etc.)

• The Optimized Design vs Reference Design: 30% n-flux improvement,

increase of heat and radiation loads in Target Station (30%) and Decay

Channel (20%), substantial mitigation of EDEP problems in Hadron

Absorber system

• Thorough search and elimination of differences in

MARS15LBNF and G4LBNF models were

performed (#3408): geometry, materials, magnetic

fields etc. n-fluxes at Far Detector calculated with

MARS15 and Geant4 now agree within 10%. The

code related uncertainties were reduced to the

differences in the event generators, especially for

K- and K0 mesons (need data!)

Documents

LBNF MARS Modeling for Optimized Beamline · LBNF Long-Baseline Neutrino Facility LBNF MARS Modeling for Optimized Beamline Nikolai Mokhov Beam Optimization Review - FNAL October