8th Nov. 2003 NBI03@KEK

J-PARC
Neutrino Beam Optimization
A.K.Ichikawa, KEK

1π production –ModelMomentum and angle of π

<θ>=const.+const./<p>
MARS 50GeV,graphite
θ=0.038+0.31/p

MARS
50GeV : θ=0.038+0.31/p
30GeV : θ=0.038+0.33/p

GFLUKA+GCALOR
50GeV : θ=0.023+0.33/p
FLUKA2000
50GeV : θ=0.026+0.31/p
Horn parameters depends
not on primary proton energy
but on focusing pion momentum~2GeV/cJ-Parc horn should be rather similar to2K2K type than NuMI or CNGS types.

Horn design starting point
Horns proposed in BNL-E889
which is appropriate for ~2GeV/c pions
1st horn

2.2m• Din = 1.9cmφ, I=250kA• Sapphire target (Al2O3, ρ=4g/cm3) D=0.64 cm, L=45cm
Cannot survive heat load from radiation at J-Parc

Need realistic design work3

Momentum region of π’s
w/ BNL-type horn, 2.5°OAB

π’s contributing Eν<1.2GeV

4

Angular region of π’s
which generate ν(Eν<1.2 GeV)

400mr

400m

400mr

5

Target Size

Effect is not large around here

90cm long graphite (2λint)•Pion absorption•Temperature rise

Hayato’stalk•Energy concentration•Inner radius of the horn

radiusσ beam =2 .5•Beam size ~1cm
Target 3cmφHorn inner conductor radius > ~45mmφ6

Types for the 1st horn
(a)

(c)

(b)

(d)

7

Target in/not-in the horn?
Inner conductor 4.6cmφI = 250 kA

Target outside the horn
4m
1m
10m
2.5GeV

1.7GeV

Target in the horn

1m
4m

3GeV

2GeV

8

Idea for ‘1st horn’~250kA,
Din~4cmφ~500kA~3m
I=250 kA

I=500kA

93cmφ

Din=5.2cmφ
45cmφ

19cmφ

35cmφ
11cmφ160cm

100cm

Collector and Focus

165cm

93 horns, I=320kA
1st horn

52mmφ

1.5m

10

Optimization procedure 1.
(optimization of 2nd and 3rd horns)
I kA

Br0, θ, p

LR0’, θ’, p’r(cm)Upstream horn

60

50

40

30

20

100-250 -225 -200 -175 -150 -125 -100 -75 -50 -25
11 0-L(cm)stHorn system –1 version?-

320kA

320kA

Din = 52mmφ

320kA

248mmφ86mm

850mmφ

φ120mmφ

1.5m

0.5m

2.0m

3.5m

2.5m

12

Further optimization –Horn1Parameters

default

Current I320kA

Inner conductor radius rin

26 mmHorn1 Length L1

1.5 m

Distance to Horn2 D20.5 m

Horn2 shape parameter a20.609

Horn3 shape parameter a30.0661

Fixed Parameters
Horn2 Length L22m

Horn3 Length L3

2.5 m

Total Length11.5 m

L1

D2

L2

D3

L3

13

Further optimization

14

What can be said w/ this?
Flux increases with higher current.
~5%/100kA
Diff.btw. 300kA & 320kA is only 2~3%.
Almost same yields with rin=26mm & 28mm,
while decreased w/ 30mm.
Yield is maximum at L1=140cm or 150cm.

I=300kA ~320kA
rin=28mm (safer than 26mm)
L1=140cm (easier than 150cm)

15

809
1400

900472

I=300kA~320kA

2000

100 cm2500

Rin = 28 mm
L1 = 140cm
D2 = 50cm

16

Flux w/ New horn
Comparison btw. optimizedversion & BNL-type(starting point)(aluminum is not included.)
Optimized version
BNL type

Optimized
Rin=28mm
30mmφ graphite target
BNL-type
Rin=9.5mm
6.4mmφ sapphire target170.017䏲

Target-SK distance=295km

Best Fit 3.43䏲
(OAB2.3䏲 Beam Axis)

1.246䏲

2䏲

3䏲

SK2䏲

1.515䏲HKDV center3䏲

2䏲

3䏲

0.783䏲

2002/10/15Condition䎃䎃䎃䎃䎃䎃䎃䎃Bessel Coodinate Direction Angle
Target E 36䏲26'45.4976"
N 140䏲36'27.7413"
H -1.7m
SK E 36䏲25'21.4935" 270.4764
N 137䏲18'48.0468"
1.2626H 321.216m
HK E 36䏲21'08"
268.9618
N 137䏲18'49"
1.2463
H 412.175m

3.103䏲(OAB2䏲 beam axis䎌
3.637䏲(OAB2.5䏲䎌
4.159䏲(OAB3䏲䎌

Downward angle
1.263䏲(44m@2km)

Target Level@Tokai

Optimization of Decay Volume -1-Peak Eν is determined by off-axis angle.

Cover this region18decay position

1250

X(cm)

(a.u.)

Optimization of Decay Volume -2200
150-110100500-210-50-100-150-310-200-250020406080

100020406080

100120Z(m)120(m)

ターゲット・ステーション(地下レベル）

1.40

コンクリートTop view

FH2FQ3A

FQ3B

FQ4

FV1

FV2

コンクリート

放射化物保管室

断面図

TS上屋

μピット機械室
(半地下)
汚染検査室
2.11

0.07µSv/hfor 1W/m
line

3NBT

TP+11.8m(0.244 µSv/h)Side View

土盛り

3NBTレベル(TP+8m)

土盛り

空隙（サービスエリア）
遮蔽ブロックTP-1.1m

TP-1.1m

コンクリートコンクリート19

FL=TP-14.3

Summary
Conceptual optimization of target, horns and decay
volume was done.
 Now, need to move imaginary world to real world!
20