Horns, Hadron production etc. (from hadron production

to neutrino beam)

A.K.Ichikawa

KEK

200/9/26 NP02@Kyoto

• Study on horns

• Changing -beam energy

• Hadron production

Study on horns

Brief comment on the horn design status Till now, in the beam MC simulation,

horns proposed in BNL-E889 was used.

2.2m

• Din = 1.9cm, I=250kA

• Sapphire target (Al2O3, =4g/cm3) D=0.64 cm, L=45cm

1st horn

c.f. K2K Din=3.0cm, I=250kA

In addition, heat load from radiation

Need realistic design work

production –Model-Momentum and angle of

=const.+const./<p>

MARS 50GeV, graphite

=0.038+0.31/p

MARS

50GeV : =0.038+0.31/p

30GeV : =0.038+0.33/p

GFLUKA+GCALOR

50GeV : =0.023+0.33/p

30GeV : =0.025+0.32/p

FLUKA2000

50GeV : =0.026+0.31/p

30GeV : =0.033+0.31/p

Momentum region of ’sw/ BNL-type horn, 2.5°OAB

’s contributing E<1.2GeV

>1.5GeV/c

>1.7GeV/c

4.4m

W/ fixed current,

r x 2 L x 2, Wx2 to obtain same optics.

2.2m

Din = 1.8cm

Din = 3.6cm

Scaling laws

BNL-type horn1

K2K horn1

OAB1o

WBB

w/ K2K horns

Din = 1.8cm

Din = 3cm

1m

Inner conductor 4.6cmI = 250 kA

1.7GeV

2GeV

2.5GeV

3GeV4m

Target in the horn

1m10m

4m

Target outside the horn

6cm, I=250kA

22cm, I=500kA

2.5m 1.4m

1m

36kA/cm2 @t=4mm 24kA/cm2 @t=3mm cf. K2K 35kA/cm2

66cm

One idea for ‘1st horn’

Till now, only 60% flux have been achieved…..

~3m

The other idea for ‘1st horn’

~250kA, Din~4cm ~500kA

Heat Load from Radiation

Graphite =1.8g/cm3

Water t=5mm

Air t=6mm

Inner cond.

Al t=4mm

In total,

34kJ/3.3E14 protons = 10 kW @ 0.3Hz

cf. K2K heat load in the target from the current

= 1.4 kW

　 (surface area ~x 7)

In the graphite target, 64kJ/3.3E14 protons in total

30mm

60mm

t~14o

ZR

ZR

Strategy to change peak energy

Change the neutrino beam energy

Side View

Top view

To SK/HK OAB 2°

OAB3°

Decay Volume

Unofficial

Dipole magnet

gap 1m×1m×1m

One method is changing the beam axis.

The other…. OAB+Bending Magnet

Oyabu’s talk

Hadron production model

jnubeam : neutrino beam simulation code

developed from K2K code

• DV shape : incorporate actual shape

• target & horns : still BNL-type.

• calculation of -flux at SK for all decays by weighting

• Hadron production model

1. Models built-in Geant3. e.g. GFLUKA..

2. Various models using Input via stdout | stdin.

> MARS | jnubeam

> FLUKA2000 | jnubeam

GFLUKA

MARS

FLUKA2000

OAB2.5o

Ep=50GeV

Graphite 0.74cm 45cm

Comparison of different proton energy and different models @ OAB2.5o

50 GeV

(1021POT)

30 GeV

(1021POT)

30 GeV

(1021 x 5/3POT)

GFLUKA 1.40 0.98 1.64

MARS 1.37 0.91 1.52

FLUKA2000 1.45 0.86 1.43

Absolute flux (E<1.5GeV)

x107/cm2/yr

e #(e)/#( E<1.5GeV)

50 GeV 30 GeV

GFLUKA 1.14% 0.87%

MARS 0.90% 0.86%

FLUKA2000 1.07% 0.83%

(Target is graphite but the dimension is BNL-type.)

Comparison of different proton energy and different models @ OAB2.5o

50 GeV 30 GeV #30 GeV/#50GeV

GFLUKA 63% 57% -9.5%

MARS 66% 61% 7.6%

FLUKA2000 64% 59% 7.8%

NC #NC/#CC(E<1.5GeV)

High Energy tail #(E>1.5GeV)/#(E<1.5GeV)

50 GeV 30 GeV #30GeV/#50GeV

GFLUKA 9.6% 7.6% 21%

MARS 11.5% 9.5% 17%

FLUKA2000 10.7% 8.8% 18%

Effects on SK observable

MARS 50 GeV

!!!! Graphite 45cm !!!!!

MARS 30 GeV

!!!! Graphite 45cm !!!!!

Pbeam=5~120 GeV/c

From R.Raja, NUFACT02

Summary or discussion item

• Horns : realistic design

gathering ideas

• Changing the beam energy

OAB vs OAB+bending

• Hadron production

MIPP

(30 GeV vs 50 GeV)

Supplement

Types for the 1st horn

(a) (b)

(c) (d)

MINOSK2K, CERN, BNL

(2nd horn)(-factory)

Beam DirectionFor both SK and possible HK.

Decay pipe

Event rate at SK MARS 50GeV

!!!Graphite 45cm target!!!