1

RAL Target Options: G4LBNF Simulations

John Back

University of Warwick

20 Dec 2018

DUNE-doc-12247

2

Introduction

• G4LBNF target simulations, using 3 horn set-up from Laura Fields’

optimization work; Geant v4.10.3

• RAL designs for graphite cylinder target & helium cooling

– Single cantilever option: target L = 1.5m

– Downstream support: target L = 1.5m to 2.3m (R. Zaki: DUNE-doc-8888)

– Double target: two L ≈ 1m sections (new)

• Looking at CP sensitivity and neutrino fluxes (vs target length L)

– Target radius fixed at r = 8mm; smallest value possible for engineering

– Proton beam: p = 120GeV/c, σR = 1

3r = 2.67mm (Gaussian)

3

Geometry for single cantilever, target L = 1.5m

0 50 100 150 200z(cm)

10−

8−

6−

4−

2−

0

2

4

6

8

10y(c

m)

4

Geometry with downstream support, target L = 1.5m (“short”)

0 50 100 150 200z(cm)

10−

8−

6−

4−

2−

0

2

4

6

8

10y(c

m)

5

Geometry with downstream support, target L = 2.2m (“long”)

0 50 100 150 200z(cm)

10−

8−

6−

4−

2−

0

2

4

6

8

10y(c

m)

6

Double target concept: z-y and x-y views

7

Double target downstream section

8

Double target: sheet & web support detail

2 mm thick Ti (grade 5): conic sheets (front & back) & web support (60 deg)

9

Geant4 geometry for double target

0 50 100 150 200z(cm)

25−

20−

15−

10−

5−

0

5

10

15

20

25y(c

m)

10

Geometry for double target: mid-section

105 110 115 120 125 130z(cm)

8−

6−

4−

2−

0

2

4

6

8y(c

m)

11

Geometry for double target: end-section

200 205 210 215 220 225 230 235z(cm)

30−

20−

10−

0

10

20

30y(c

m)

12

Geometry for double target: x-y view of 6 web manifold

25− 20− 15− 10− 5− 0 5 10 15 20 25x(cm)

25−

20−

15−

10−

5−

0

5

10

15

20

25y(c

m)

13

CP sensitivity versus target length

1.5 1.6 1.7 1.8 1.9 2 2.1 2.2 2.3Target length (m)

1.9

1.92

1.94

1.96

1.98

2

2.02

2.04

2.06

2.08

2.1

CP

sen

sit

ivit

y (

75%

)

= r/3σRAL cylindrical target, r = 8 mm. Beam: p = 120 GeV/c,

With downstream support

Single cantilever

Double target

14

Neutrino running: signal muon neutrino flux

0 1 2 3 4 5 6 7 8 Energy (GeV) µν

0

10

20

30

40

50

910×

/ y

ear

2s / G

eV

/ m

µνU

nosc

Target options

Cantil L = 1.5 m

L = 1.5 m

L = 1.8 m

L = 2.1 m

Double L = 2.1 m

0 1 2 3 4 5 6 7 8 Energy (GeV) µν

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

Flu

x r

atio w

.r.t c

antile

ver

option

Target options

Cantil L = 1.5 m

L = 1.5 m

L = 1.8 m

L = 2.1 m

Double L = 2.1 m

Single upstream cantilever option: Cantil L = 1.5 m

Double target: Double L = 2.1 m

Others: 1 target with downstream support: L = 1.5, 1.8 & 2.1 m

Left: Flux spectrum, Right: Bin-by-bin flux(downstream)/flux(cantilever)

15

Antineutrino running: signal muon antineutrino flux

0 1 2 3 4 5 6 7 8 Energy (GeV)µν

0

10

20

30

40

50

910×

/ y

ear

2s / G

eV

/ m

µνU

nosc

Target options

Cantil L = 1.5 m

L = 1.5 m

L = 1.8 m

L = 2.1 m

Double L = 2.1 m

0 1 2 3 4 5 6 7 8 Energy (GeV)µν

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

Flu

x r

atio w

.r.t c

antile

ver

option

Target options

Cantil L = 1.5 m

L = 1.5 m

L = 1.8 m

L = 2.1 m

Double L = 2.1 m

Single upstream cantilever option: Cantil L = 1.5 m

Double target: Double L = 2.1 m

Others: 1 target with downstream support: L = 1.5, 1.8 & 2.1 m

Left: Flux spectrum, Right: Bin-by-bin flux(downstream)/flux(cantilever)

16

Neutrino running: bkgnd antimuon neutrino flux

0 1 2 3 4 5 6 7 8 Energy (GeV)µν

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5910×

/ y

ear

2s / G

eV

/ m

µνU

nosc

Target options

Cantil L = 1.5 m

L = 1.5 m

L = 1.8 m

L = 2.1 m

Double L = 2.1 m

0 1 2 3 4 5 6 7 8 Energy (GeV)µν

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

Flu

x r

atio w

.r.t c

antile

ver

option

Target options

Cantil L = 1.5 m

L = 1.5 m

L = 1.8 m

L = 2.1 m

Double L = 2.1 m

Single upstream cantilever option: Cantil L = 1.5 m

Double target: Double L = 2.1 m

Others: 1 target with downstream support: L = 1.5, 1.8 & 2.1 m

Left: Flux spectrum, Right: Bin-by-bin flux(downstream)/flux(cantilever)

17

Antineutrino running: bkgnd muon neutrino flux

0 1 2 3 4 5 6 7 8 Energy (GeV) µν

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5910×

/ y

ear

2s / G

eV

/ m

µνU

nosc

Target options

Cantil L = 1.5 m

L = 1.5 m

L = 1.8 m

L = 2.1 m

Double L = 2.1 m

0 1 2 3 4 5 6 7 8 Energy (GeV) µν

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

Flu

x r

atio w

.r.t c

antile

ver

option

Target options

Cantil L = 1.5 m

L = 1.5 m

L = 1.8 m

L = 2.1 m

Double L = 2.1 m

Single upstream cantilever option: Cantil L = 1.5 m

Double target: Double L = 2.1 m

Others: 1 target with downstream support: L = 1.5, 1.8 & 2.1 m

Left: Flux spectrum, Right: Bin-by-bin flux(downstream)/flux(cantilever)

18

Summary

• Longer target provides slightly higher CP sensitivities, with higher signal νµ &

lower ν̄µ background fluxes

• Single cantilever option (L = 1.5m, easier engineering design) gives ∼ 98% of the

CP sensitivity of L ≈ 2.1m with downstream support

– Signal νµ flux reduced by ∼ 5% for Eν . 2GeV

– Signal νµ flux increased by ∼ 2–4% for 2 < Eν . 4GeV

– Background ν̄µ fluxes for Eν & 1GeV increased

• Double target L = 2.1m performance similar to L = 1.9m single target

– ∼ 99% of the CP sensitivity of L ≈ 2.1m (with downstream support)

– π through metal sheets: ≈ 4mm Ti ⇒ 1.4% of an interaction length

– Downstream Ti on-axis is a good target material

∗ See hybrid target studies: DUNE-doc-2437

19

Downstream (single target) & upstream (all) supports

Upstream figure courtesy Rowan Zaki: helium cooling sections.

Downstream support for sin-gle target with radial coolingtubes

20

Neutrino running: bkgnd electron neutrino flux

0 1 2 3 4 5 6 7 8 Energy (GeV)eν

0

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4

0.45

0.5910×

/ y

ear

2s / G

eV

/ m

eνU

nosc

Target options

Cantil L = 1.5 m

L = 1.5 m

L = 1.8 m

L = 2.1 m

Double L = 2.1 m

0 1 2 3 4 5 6 7 8 Energy (GeV)eν

0.5

1

1.5

2

2.5

Flu

x r

atio w

.r.t c

antile

ver

option

Target options

Cantil L = 1.5 m

L = 1.5 m

L = 1.8 m

L = 2.1 m

Double L = 2.1 m

Single upstream cantilever option: Cantil L = 1.5 m

Double target: Double L = 2.1 m

Others: 1 target with downstream support: L = 1.5, 1.8 & 2.1 m

Left: Flux spectrum, Right: Bin-by-bin flux(downstream)/flux(cantilever)

21

Antineutrino running: bkgnd antielectron neutrino flux

0 1 2 3 4 5 6 7 8 Energy (GeV)eν

0

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4

0.45

0.5910×

/ y

ear

2s / G

eV

/ m

eνU

nosc

Target options

Cantil L = 1.5 m

L = 1.5 m

L = 1.8 m

L = 2.1 m

Double L = 2.1 m

0 1 2 3 4 5 6 7 8 Energy (GeV)eν

0.5

1

1.5

2

2.5

Flu

x r

atio w

.r.t c

antile

ver

option

Target options

Cantil L = 1.5 m

L = 1.5 m

L = 1.8 m

L = 2.1 m

Double L = 2.1 m

Single upstream cantilever option: Cantil L = 1.5 m

Double target: Double L = 2.1 m

Others: 1 target with downstream support: L = 1.5, 1.8 & 2.1 m

Left: Flux spectrum, Right: Bin-by-bin flux(downstream)/flux(cantilever)

22

Neutrino running: bkgnd antielectron neutrino flux

0 1 2 3 4 5 6 7 8 Energy (GeV)eν

0

10

20

30

40

50

60

70

80610×

/ y

ear

2s / G

eV

/ m

eνU

nosc

Target options

Cantil L = 1.5 m

L = 1.5 m

L = 1.8 m

L = 2.1 m

Double L = 2.1 m

0 1 2 3 4 5 6 7 8 Energy (GeV)eν

0.5

1

1.5

2

2.5

Flu

x r

atio w

.r.t c

antile

ver

option

Target options

Cantil L = 1.5 m

L = 1.5 m

L = 1.8 m

L = 2.1 m

Double L = 2.1 m

Single upstream cantilever option: Cantil L = 1.5 m

Double target: Double L = 2.1 m

Others: 1 target with downstream support: L = 1.5, 1.8 & 2.1 m

Left: Flux spectrum, Right: Bin-by-bin flux(downstream)/flux(cantilever)

23

Antineutrino running: bkgnd electron neutrino flux

0 1 2 3 4 5 6 7 8 Energy (GeV)eν

0

10

20

30

40

50

60

70

80610×

/ y

ear

2s / G

eV

/ m

eνU

nosc

Target options

Cantil L = 1.5 m

L = 1.5 m

L = 1.8 m

L = 2.1 m

Double L = 2.1 m

0 1 2 3 4 5 6 7 8 Energy (GeV)eν

0.5

1

1.5

2

2.5

Flu

x r

atio w

.r.t c

antile

ver

option

Target options

Cantil L = 1.5 m

L = 1.5 m

L = 1.8 m

L = 2.1 m

Double L = 2.1 m

Single upstream cantilever option: Cantil L = 1.5 m

Double target: Double L = 2.1 m

Others: 1 target with downstream support: L = 1.5, 1.8 & 2.1 m

Left: Flux spectrum, Right: Bin-by-bin flux(downstream)/flux(cantilever)

24

Signal muon integrated flux ratios

0 1 2 3 4 5 6 7 8 Energy (GeV) µν

0.6

0.7

0.8

0.9

1

1.1

1.2

1.3

Inte

gra

ted

Flu

x R

ati

o

Target options

Cantil L = 1.5 m

L = 1.5 m

L = 1.8 m

L = 2.1 m

Double L = 2.1 m

Neutrino Running

0 1 2 3 4 5 6 7 8 Energy (GeV)µν

0.6

0.7

0.8

0.9

1

1.1

1.2

1.3

Inte

gra

ted

Flu

x R

ati

o

Target options

Cantil L = 1.5 m

L = 1.5 m

L = 1.8 m

L = 2.1 m

Double L = 2.1 m

Antineutrino Running

Single upstream cantilever option: Cantil L = 1.5 m

Double target: Double L = 2.1 m

Others: 1 target with downstream support: L = 1.5, 1.8 & 2.1 m

Integrated flux I in ν energy bin (E1, E2) = Σ flux between E1 and E2

Integrated flux ratio = I(downstream support)/I(cantilever)

25

Background antimuon integrated flux ratios

0 1 2 3 4 5 6 7 8 Energy (GeV)µν

0.6

0.7

0.8

0.9

1

1.1

1.2

1.3

Inte

gra

ted

Flu

x R

ati

o

Target options

Cantil L = 1.5 m

L = 1.5 m

L = 1.8 m

L = 2.1 m

Double L = 2.1 m

Neutrino Running

0 1 2 3 4 5 6 7 8 Energy (GeV) µν

0.6

0.7

0.8

0.9

1

1.1

1.2

1.3

Inte

gra

ted

Flu

x R

ati

o

Target options

Cantil L = 1.5 m

L = 1.5 m

L = 1.8 m

L = 2.1 m

Double L = 2.1 m

Antineutrino Running

Single upstream cantilever option: Cantil L = 1.5 m

Double target: Double L = 2.1 m

Others: 1 target with downstream support: L = 1.5, 1.8 & 2.1 m

Integrated flux I in ν energy bin (E1, E2) = Σ flux between E1 and E2

Integrated flux ratio = I(downstream support)/I(cantilever)

26

Background electron integrated flux ratios

0 1 2 3 4 5 6 7 8 Energy (GeV)eν

0.7

0.8

0.9

1

1.1

1.2

1.3

1.4

Inte

gra

ted

Flu

x R

ati

o

Target options

Cantil L = 1.5 m

L = 1.5 m

L = 1.8 m

L = 2.1 m

Double L = 2.1 m

Neutrino Running

0 1 2 3 4 5 6 7 8 Energy (GeV)eν

0.7

0.8

0.9

1

1.1

1.2

1.3

1.4

Inte

gra

ted

Flu

x R

ati

o

Target options

Cantil L = 1.5 m

L = 1.5 m

L = 1.8 m

L = 2.1 m

Double L = 2.1 m

Antineutrino Running

Single upstream cantilever option: Cantil L = 1.5 m

Double target: Double L = 2.1 m

Others: 1 target with downstream support: L = 1.5, 1.8 & 2.1 m

Integrated flux I in ν energy bin (E1, E2) = Σ flux between E1 and E2

Integrated flux ratio = I(downstream support)/I(cantilever)

27

Background antielectron integrated flux ratios

0 1 2 3 4 5 6 7 8 Energy (GeV)eν

0.7

0.8

0.9

1

1.1

1.2

1.3

1.4

Inte

gra

ted

Flu

x R

ati

o

Target options

Cantil L = 1.5 m

L = 1.5 m

L = 1.8 m

L = 2.1 m

Double L = 2.1 m

Neutrino Running

0 1 2 3 4 5 6 7 8 Energy (GeV)eν

0.7

0.8

0.9

1

1.1

1.2

1.3

1.4

Inte

gra

ted

Flu

x R

ati

o

Target options

Cantil L = 1.5 m

L = 1.5 m

L = 1.8 m

L = 2.1 m

Double L = 2.1 m

Antineutrino Running

Single upstream cantilever option: Cantil L = 1.5 m

Double target: Double L = 2.1 m

Others: 1 target with downstream support: L = 1.5, 1.8 & 2.1 m

Integrated flux I in ν energy bin (E1, E2) = Σ flux between E1 and E2

Integrated flux ratio = I(downstream support)/I(cantilever)