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Meson Production Simulations

X. Ding, D. B. Cline UCLA

H. Kirk, J. S. Berg BNL

N u F a c t 0 9

11th International Workshop onNeutrino Factories, Superbeams and Beta Beams

July 20-25, 2009 — IlT — Chicago

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Outline

• Mercury Target Geometry and Optimized Target Parameters (Beam below Mercury Jet)

• Beam Initial Position, Beam/Jet Crossing Angle and Beam Path Length inside the Hg Jet (Beam below Mercury Jet)

• Multiple Proton Beam Entry Directions (Beam around Mercury Jet)

• Meson Production • Summary

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Neutrino Factory Target Concept

SC Coils

Cu Coils

Fe Plug

Hg Containment

Hg Pool

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Mercury Target Geometry

1. The proton beam is below the Hg jet at z=-75cm.2. Count all the pions and muons of positives and negatives that cross the transverse plane at z=50m.3. For this analysis we select all pions and muons with

40MeV<KE<180MeV.

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Optimized Target Parameters at z=-75cm

1. Beam and Jet cross only at z=-37.5cm. Beam angles also vary at different z. So the crossing angle at z=-75cm actually means the angle between beam moving direction and jet.

2. Previous Baseline: radius of 0.5cm,beam angle of 67mrad and beam/jet crossing angle of 33mrad.

0.3

0.35

0.4

0.45

0.5

0.55

0.6

0.65

0 10 20 30 40 50 60 70 80 90 100

TargetRadius,cm

Proton Kinetic Energy, GeV

0

20

40

60

80

100

120

140

0 10 20 30 40 50 60 70 80 90 100

BeamAngle,mrad

Proton Kinetic Energy, GeV

-5

0

5

10

15

20

25

30

0 10 20 30 40 50 60 70 80 90 100

CrossingAngle,mrad

Proton Kinetic Energy, GeV

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Meson Production w/wt Optimization

0

0.005

0.01

0.015

0.02

0.025

0.03

0.035

0.04

0 10 20 30 40 50 60 70 80 90 100

Mesons/protons/GeV

Proton Kinetic Energy, GeV

without optimizationwith optimization

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Required Beam Initial Position at z=-75cm to Achieve x=y=0 at z=-37.5cm)

0 20 40 60 80 100

0.0

0.2

0.4

0.6

0.8

1.0

1.2

Initi

al p

ositi

on o

f be

am (

x0),

cm

Proton Kinetic Energy, GeV

Initial position (x0) vz. KE

0 20 40 60 80 1002.6

2.8

3.0

3.2

3.4

3.6

3.8

4.0

4.2

4.4

4.6

Initi

al p

ositi

on (

y0),

cm

Proton Kinetic Energy, GeV

Initial position (y0) vz. KE

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Effect of Different Beam Initial Position

0.319

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Beam/Jet Crossing Angle at z=-75cm and z=-37.5cm

8GeV, 18.55mrad at z=-75cm and 27.05mrad at z=-37.5cm

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Beam Path Length inside the Mercury Jet

Nuclear interaction length for Hg is 14.58cm

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Multiple Proton Beam Entry Directions 8GeV, Roll angle(Φ): Telling us what side of the jet the

beam is on. (below: Φ=π, up: Φ=0, left: Φ= π/2,

right: Φ=3π/2) Clearance: Telling us the extent of proton beam

away from the Hg jet at z=-75cm.

xj=0, yj=3.64cm. (x0, y0) is beam initial position.

jbjj rcmrmrad 3.0,4.0,68.96

b

jjj ryyxxC

2

02

0

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Multiple Proton Beam Entry DirectionsThe Required Beam Position at z=-75cm to Keep Same Crossing Angle and 240 Roll Angle Apart at z=-37.5cm

p0

p4

p8

p12 jet(0, 3.64)

y

x

Previous Incident Beam at z=-75cm for optimization

p1p2

p3

p5

p6p7

p9

p10

p11

p13

p14

4.3% higher in meson production at p11 than at p6

=00

=960

=2640

=1920

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Multiple Proton Beam Entry Directionsx-y plot of proton relative to jet at different z

-1.6 -1.4 -1.2 -1.0 -0.8 -0.6 -0.4 -0.2 0.0 0.2 0.4 0.6-1.2

-1.0

-0.8

-0.6

-0.4

-0.2

0.0

0.2

0.4

0.6

0.8

1.0

z=-37.5cm

p14, z=-75cm

p11, z=-75cm

p8, z=-75cm

p5, z=-75cm

p2, z=-75cm

Vary z from -75cm to -37.5cm in steps of 2.5cmY

(pro

ton)

-Y(j

et),

cm

X(proton)-X(jet), cm

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Multiple Proton Beam Entry Directions

-50 0 50 100 150 200 250 300 350 4000

10

20

30

40

50

60

70

80

90

100

110

120

130A

ngle

, mra

d

Roll Angle, degree

Beam/Jet Crossing Angle (z=-37.5cm) Beam/Jet Crossing Angle (z=-75cm) Beam Angle to Solenoid Axis (z=-75cm) Hg Jet Angle to Solenoid Axis

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Multiple Proton Beam Entry DirectionsClearance at z=-75cm for Same Crossing Angle and

240 Roll Angle apart at z=-37.5cm

p0

p4

p6

p11

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Multiple Proton Beam Entry DirectionsMeson 40MeV<KE<180 MeV at 50m for Same Crossing

Angle and 240 Roll Angle apart at z=-37.5cm

p11

p6

p4

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Increasing Clearance of p4

26 28 30 32 34 36 38 40 42 441

2

3

4

5

6

7

Cle

aran

ce

Crossing angle of beam/jet, mrad

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Normalized Meson Production(beam below jet)

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Normalized Mesons at 50m(beam below jet)

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Summary• Target parameters of incident beam below Hg target and KE from 2 to 100GeV are optimized.• Beam angles and beam/jet crossing angles vary at low KE due to magnet field. • The beam path length inside the jet is less than 2 times of the Hg interaction length at low KE.• Layouts of multiple proton beam entry directions relative to the Hg jet at z=-75cm are determined to achieve the same crossing angle at z=-37.5cm. • There is about 4% increase in meson production at p11 compared to p6.