7th Nov. 2003, NBI03@KEK

J-Parc Neutrino Facility
Primary Proton Beam Design
A. K. Ichikawa(KEK),
Y.Iwamoto(KEK) and K.Tanabe(Tokyo)
et.al.

Overviewン型
サスペンショt x 2)クレーン(20PQ2A

PC2

PV2
PQ5PH3

PC4

PC3

PC1

PV1

PD2

PD1
1.92 deg. bend

引き出し基準点
x=49615028.58, y=69561283.94

PQ1PH2PH1

1.92 deg. bend

PQ3

PQ4

ニュートリノ・ビームライン

Preparation section
Normal conducting

Arc Section
R=105mSuper conducting¾Single turn fast extraction¾8 bunches/~5µs

FH1 FQ1¾3.3x1014proton/pulse

FH2FQ2FQ3FV1FQ4

ビーム振り下げFinal Focusing
SectionNormal conducting¾3.94 (3.64) sec cycle(depend on abort scenario)¾ε=6π mm.mr, ∆p/p=0.31% @50GeV¾ε=7.5π mm.mr, ∆p/p=0.36% @30GeV

FV2¾Total bending = 84.5o

Beam loss

ョン型サスペンシt x 2)クレーン(20PQ2A

PC2PV2PQ550GeV ring
0.5W/mPH3PC4PC3PC1

PV1PD2PD11.92 deg. bend

引き出し基準点
x=49615028.58, y=69561283.94

PQ1PH2PH11.92 deg. bend

PQ3PQ4

ニュートリノ・ビームライン

Fast ext.(kicker, septum)
1.125kW (0.15%)
Preparation section(ctrl’ed loss by collimator)
0.75kW (0.1%)
Final Focusing section
0.25kW (0.05%)



FH1 FQ1



FH2
FQ2FQ3

FV1
FQ4

ビーム振り下げFV2



No way to know absolutebeam loss
Assumed by HAND
Assure hands on maintenance(1W/m)
Shielding design based on theassumption
Same order as KEK-PS beamline
Î ~102 relative
suppression!!ÎChallenging

Boundary Condition for the designo¾ about 80 bending¾ R~105 m

Super conducting magnet¾ Beam size in the arc should be as small as possible to prevent quenching¾ Beam halo should be cut at Preparation section

Collimator

Two candidates for the arc section design
9 (Separate Function) FODO x10 (20 D’s & 20 Q’s)

QDQ

9 Combined function FODO x14 (28 magnets)

Bx = Q*y/r
By = D + Q*x/r

D

Combined Function–Merit & Demerit?¾MeritReduce # of components
can increase # of (Q-)magnets.
Smaller beam size
space btw magnets
monitor can be installed
cost reduction¾Demerit
No example in the world
Tunnability is restrictedneed corrector?

We adopt combined function scheme !

Treatment of Combined function w/ SAD
B y = BD + Qgrad × x= Qgrad ( x − ∆x)BD∆x = −Qgrad

Quadrupole magnet displaced by ∆x.

Fitting parameters,∆x (by hand), Qgrad, angle of magnet
Fitting condition for the cell(a) Periodic(b) 90o phase advance(c) Align orbit and magnet at this pointf or each of two magnets(d) Bend by 5.76oArc section optics (fitting result)
K1 = 0.18085
dB yBρ
= K1× o = 18.620T / mdx
LdB y× ∆x = 2.5863T
B y (dipole) =dx

3.3m

1.4m

1.1m

1.4m

Admittance : 205π mm.mr for horizontal,

Simulation Study (w/ GEANT3 & Geant4)•Magnet w/ Iron poles are stationed.
•Particles are tracked.
•Particle interact w/ magnet accoring tohadron production model.
•Secondary hadrons and electro
magnetic showers can be traced.

Magnet geometry and field are
set via data file.
applicable to different
beamlines.

In the simulation,
combined function section works as
expected from optics calculation!

by Y. Iwamoto

Arc section Admittance-quadrapole field changex,dp/p=0%x,dp/p=0.4%
x,dp/p=2%

Admittance (π mm.mr)

220

200-10%Admittance calculation
with quadrupole field changed by
0, 1, 2 and 5 %.
The momentum bite was assumed
to be 0, 0.2 and 0.4%.

180

160

14012017.5

Admittance changes about 10 %with quadrupole field decreased by 2 %.

18.62T/m+0%1818.5

1919.5

Quadrupole field (T/m)

20

Maximum is at quadrupole field increasedby 1 %.

by Y. Iwamoto

Arc section Admittance-higher component x + iy 
B = B y + iBx =(bn + ian )
∑10000 n =1
 Rref Bref∞x,dp/p=0%x,dp/p=0%,
with multipole
field up to 18

220

Admittance (π mm.mr)

bn: dipole component
an: skew component
Bref: reference field
Rref: reference radius
n=1, 2n=1, 2, ..., 18

200

dipole and quadrupole field
multipole field180

Effect of the multipole field is small.

160
18.62T/m
+0%

140
17.5

18

18.5

19

19.5

Quadrupole field (T/m)

20

by Y. Iwamoto

Arc Section Admittance-Alignment error205π for no error-0.1 mm < dx < 0.1 mm

210

210
max=207 ave=203

ave=204Admittance (π mm.mr)

205

200
min=201

195

205

200min=199

195

max=207

Admittance (π mm.mr)

max=207

Admittance (π mm.mr)-0.3 mm < dx < 0.3 mm-0.2 mm < dx < 0.2 mm

210

ave=201

205

200

195
min=194

190

0204060

samples

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190

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samples

80

1000204060

samples

Acceptable alignment error of dx is ± 0.2 mm.
dy is ± 0.2 mm.
dz is ± 5.0 mm.

80

100

However, admittance can be recoveredby changing the field strength to some extent

220200Admittance (π mm.mr)

With the set up for
dx=0.3mm 、adm=194π18016014012010080-2-1.5-1-0.5

0%

0.5

11.5

2

Do we need corrector magnet for
the arc section?
The ratio of the quadrapole field and dipole field is fixed.
Correction scheme -> T.Ogitus’s talk.
It will be decided within this year.

Preparation section –Overview9Make matching with the Arc.
9Consists of normal conducting magnets.
9Almost no freedom on the Length and angle
9Total Length : 52.3m → Tight spacing
93.84 degrees bending
9Scrape beam halo to protect super conducting magnet in the Arc

Preparation Section –opticsPrep. section

Arc section~1cmMonitorbeam
horizontal
verticalWell Matched w/ ArccollimatorPreparation section

Acceptance : 60π mm.mr (c.f. Acc. design = 6π mm.mr)

Focusing Section
Beam should fit to target (30mmφ)

ε=6π mm.mr

Arc section

whatever the emittance is.

Focus 6~24π beam
Accept 60π beam.

Vertical steering magnet
Change off-axis angle w/ this.

SummaryJ-Parc Neutrino beamline must transport highintensity(0.75 MW) proton beam with 0.01~0.1% loss.
 We adopt super-conducting combined-function magnets
for the arc section.
 Simulation study for the possible beam loss sources andhalo scraper (see Tanabe’s talk) is on going.
 Current big subject is a decision about corrector magnet
for the combined function magnet.
Supplement

Arc section – fitting resultsK1 = 0.18085
Bo ρ= K1×= 18.620T / mdx
LdB y
B y (dipole) =× ∆x = 2.5863Tdx

ビーム方向3300

3300

Admittance : 165π mm.mr for horizontal,
262π mm.mr for vertical

14001.40°9.99

9.99

10.06

1100

30.34

1400

32.57

10.06

1.48°

dB y

Acceptance and collimator study using
Geant Magnet geometry and field are
set via data file.
Preparation section

applicable to different
beamlines.

Arc60π mm.mr beam
1,000 events
Tune collimator
aperture

100π mm.mr beam
500 protons

The set-up in GEANT3 calculation

Magnetic length
30cm 330cm 30cm

Beam pipe in CFM（φ13cm)Beam pipe（φ20cm)

30cm

30cm

Incident beam size in x-x’ phase space is 2000π.
(x: horizontal, y: vertical)

Focus 24π mm.mr beam

15mm

Momentum dispersion at target∆p≈ 600mm /p
2.4mm @ ∆p/p=0.4%

Cannot be zero due tolimitation of beam line length.
Zero is preferable but this isacceptable.

Incident beam size in x-x’ phase space is 1000π.
-5 mm < dz < 5 mm

-2 mm < dz < 2 mm

200

195

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samples

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205

100

190

210

Admittance (π mm.mr)

205

Admittance (π mm.mr)

Admittance (π mm.mr)

210

190

-8 mm < dz < 8 mm

210

200

195

0204060

samples

80

100

205

200

195

190

0204060

samples80100

Incident beam size in y-y’ phase space is 1000π.
-0.1 mm < dy < 0.1 mm

300295290

Admittance (π mm.mr)

300

Admittance (π mm.mr)

Admittance (π mm.mr)-0.3 mm < dy < 0.3 mm-0.2 mm < dy < 0.2 mm

300

295

290285

285

280

280

020406080

100

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samples

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100

295

290285280

020406080

samplessamplesBeam size in x-x’ plane はやってませんでした・・。

100Incident beam size in x-x’ phase space is 1000π.

200

195

205

2001951900204060

samples

80

100

210

Admittance (π mm.mr)

205

190

-1 degrees <dφ< 1 degrees

210

Admittance (π mm.mr)

Admittance (π mm.mr)-0.5 degrees <dφ< 0.5 degrees-0.3 degrees <dφ< 0.3 degrees

210

0204060

samples

80100

205200195

1900204060

samples80100