1

Question to the 50GeV group• 3GeVからの 54πと 81π、 6.1πの関係

•　 fast extraction部の acceptance (81π?)

•　 Comments on neutrino beamline optics?

2

Optics of Primary Proton Beam line

A. K. Ichikawa(KEK),

12th Nov. 2003, nuTAC@KEK

3ビーム振り下げ

FH1

FQ1

1.9 2 deg. bend

1.92 deg. bend

引き出し基準点x=49615028.58, y=69561283.94

ニュートリノ・ビームライン

PQ2A

FV2

FQ4

FV1

FQ3

FH2

FV2

FQ2

Overview

Preparation sectionNormal conducting

Arc Section R=105m

Super conducting

Final Focusing SectionNormal conducting

Single turn fast extraction

8 bunches/~5s

3.3x1014proton/pulse

3.94 (3.64) sec cycle

(depend on abort scenario)

=6 mm.mr, p/p=0.31% @50GeV

=7.5 mm.mr, p/p=0.36% @30GeV

Total bending = 84.5o

4ビーム振り下げ

FH1F

Q1

PD11.92 deg. bend

PC4PQ5 PH3

PC3 PQ3PQ4

PV2PC2

PC11.92 deg. bend

PD2PV1

引き出し基準点x=49615028.58, y=69561283.94

ニュートリノ・ビームライン

PQ2A PQ1

PH1PH2

サスペンション型

(20t x 2)クレーン

FV2

FQ4

FV1

FQ3

FH2

FV2

FQ2

Beam loss

No way to know absolute beam loss

Assumed by HAND Assure hands on maintenance

(1W/m) Shielding design based on the

assumption Same order as KEK-PS beam

line ~102 relative suppression!!

Challenging

Fast ext.(kicker, septum)1.125kW (0.15%)

Preparation section(ctrl’ed loss by collimator)

0.75kW (0.1%)

50GeV ring0.5W/m

Final Focusing section0.25kW (0.05%)

5

3.3m

1.1m1.4m 1.4m

Arc section optics (fitting result)

TxdxdB

B

mTLBK

dxdBK

yy

oy

5863.2)dipole(

/620.181

18085.01

Admittance : 205 mm.mr for horizontal,

294 mm.mr for vertical

6

Preparation section –Overview-

Make matching with the Arc.

Consists of normal conducting magnets.

Almost no freedom on the Length and angle

Total Length : 52.3m → Tight spacing

3.84 degrees bending

Scrape beam halo to protect super conducting magnet in the Arc

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Preparation Section –optics-

beam

Arc sectionPrep. section

Well Matched w/ Arc

Monitor

horizontal

vertical

collimator

~1cm

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Concept of our ‘collimator’

Scrape very peripheral halo only.

Preparation and Focusing sections accept 60 mm.mr beam.

Arc section accept >200 mm.mr beam.

, while extracted beam is expected to have 6~10 mm.mr emittance.

Put where we can put

Preparation section consists of many normal-conducting magnets.

The magnets themselves works as collimators for the arc section.

Iron block collimators will be added to empty places to support the halo scraping.

This is very much different from sophisticated scrapers for accelerators.

Not movable, probably no cooling

9

Preparation section

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

10

CollimatorsRadiation shield at the exit of the preparation section

Radiation Dose at conventional magnet in preparation section

Simulation study for preparation section collimators

Preparation section

11

Focusing Section

Beam should fit to target (30mm)

whatever the emittance is.

Focus 6~24 beam

Accept 60 beam.

Vertical steering magnetChange off-axis angle w/ this.

12

Focus 6 mm.mr beam

Arc section

Monitor

horizontal

vertical

15mm

13

Focus 24 mm.mr beam

15mm

14

Momentum dispersion at target

ppmm

/600

2.4mm @ p/p=0.4%

Cannot be zero due to limitation of beam line length.

Zero is preferable but this is acceptable.

15

Supplement

16

ビーム方向

1400

1.48°

3300

10.06 10.06

1100

3300

9.99

9.99

1400

1.40°30

. 34

32.57

Arc section – fitting results-

TxdxdB

B

mTLBK

dxdBK

yy

oy

5863.2)dipole(

/620.181

18085.01

Admittance : 165 mm.mr for horizontal,

262 mm.mr for vertical

17

Boundary Condition for the design

about 80o bending

R~105 m

Beam size in the arc should be as small as possible to prevent quenching

Beam halo should be cut at Preparation section

Super conducting magnet

Collimator

Bx = Q*y/r

By = D + Q*x/r

Two candidates for the arc section design

(Separate Function) FODO x10 (20 D’s & 20 Q’s)

Combined function FODO x14 (28 magnets)

Q D Q D

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Combined Function –Merit & Demerit?-

MeritReduce # of components

can increase # of (Q-)magnets. Smaller beam sizespace btw magnets monitor can be installedcost reduction

DemeritNo example in the worldTunnability is restricted

need corrector?

After discussion on 6th March 2003 with experts,

we adopt combined function scheme !

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Treatment of Combined function w/ SAD

grad

grad

grad

)(

QBx

xxQ

xQBB

D

Dy

Quadrupole magnet displaced by x.

Fitting condition for the cell

(a) Periodic

(b) 90o phase advance

(c) Align orbit and magnet at this point

f or each of two magnets

(d) Bend by 5.76o

Fitting parameters,

x (by hand), Qgrad, angle of magnet

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Simulation Study (w/ GEANT3 & Geant4)

Magnet geometry and field are set via data file.

applicable to different beamlines.

•Magnet w/ Iron poles are stationed.•Particles are tracked.•Particle interact w/ magnet accoring to hadron production model.•Secondary hadrons and electro magnetic showers can be traced.

In the simulation,

combined function section works as

expected from optics calculation!

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Final Focus

Arc

Preparation section

Simulation Setup with Geant4

x

x’These input parameters were fixed, and relative variation of beam loss were estimated.

Input beam parameter for ‘halo’

TWISS : same as those from 50 GeV design

=0~200 mm.mr

(uniformly distribute in the phase space)

p/p =2%

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Simulated beam loss at each components

Total beam loss in Preparation section is assumed 750W (0.1%) by hand.

ArcFFTotal beam loss 750W

3.7W

On this assumption, energy deposited in each components were normalized.

Preparation section

Total loss deposited in components 508W

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Radiation dose at the magnets in Preparation Section