Progress on the Linac and RLAscasa.jlab.org/.../2011/EUROnu-2011/kbb2L.euronu.pdf, 2011. Linac –...

Operated by JSA for the U.S. Department of Energy

Muons, Inc.3rd EUROnu Annual Meeting, Jan. 18th, 2011

Alex Bogacz, Vasiliy Morozov, Yves Roblin, Jefferson Lab

Kevin Beard, Muons Inc.

Progress on the Linac and RLAs

at Jefferson Lab



Linac and RLAs – ‘Big picture’

0.6 GeV/pass3.6 GeV

0.9 GeV244 MeV

146 m

79 m

2 GeV/pass

264 m12.6 GeV

IDS Goals:Define beamlines/lattices for all components

Resolve physical interferences, beamline crossings etc

Error sensitivity analysis

End-to-end simulation (machine acceptance)

Component count and costing

prelinac

RLA I

RLA II



Solenoid Linac (244 -909 MeV)

6 short cryos

15 MV/m

8 medium cryos

17 MV/m11 long cryos

17 MV/m

1.1 Tesla solenoid 1.4 Tesla solenoid 2.4 Tesla solenoid

Transverse acceptance (normalized): (2.5)2εΝ = 30 mm rad

Longitudinal acceptance: (2.5)2 σ∆pσz/mµc = 150 mm

1460

Sat Dec 13 22:36:02 2008 OptiM - MAIN: - D:\IDS\PreLinac\Sol\Linac_sol.opt

BETA_X BETA_Y DISP_X DISP_Y



Solenoid Model (Superfish)

outer coil

inner coil

shield

2epc

∞

∞

Φ − = −

∫

22 2

edge z 0-

1 k a= B (s) ds B L2 8

epc 0k = B

‘Soft-edge’ Solenoid

21Ls

a

− −

z 0

1B (s) = B tanh2



Two-cell cavity (201 MHz) – COMSOL

Morteza Aslaninejad

Cristian Bontoiu

Jürgen Pozimski



LEMC2009 workshop 8-12 Jun 2009

G4beamline model




phases from spreadsheet

phases partially adjusted




Comparison of GPT, OptiM, g4beamline

z[cm]

KE[MeV]

KE[MeV]

z[cm]

OptiM

G4beamline w/adj. φ's

G4beamlinew/OptiM's φ's

GPT



Linac – near term plans

greatly improve RF phasing capability of G4beamlineoptical rematch of linac to cooling channel

optimize longitudinal and transverse acceptance

determine energy deposition in components

prepare the transfer line to RLA I

finish the standard for exchanging data files



RLA I

0.6 GeV/pass 3.6 GeV

244 MeV

146 m

79 m

2 GeV/pass

264 m

12.6 GeV

prelinac

RLA I

RLA II

0.9 GeV



Injection/Extraction Chicane

1.5 GeV

$Lc = 60 cm$angH = 9 deg.$BH = 10.2 kGauss

2.1 GeV

$Lc = 60 cm$angV = 5 deg.$BV = 4.7 kGauss

H -H V H-H-V3 cells

4 cells

300

300

1-1

BET

A_X&

Y[m

]

DIS

P_X&

Y[m

]


FODO lattice:900/1200 (h/v) betatron phase adv. per cell

Double achromat Optics

µ+

µ+ µ−

µ−µ+ µ−0.9 GeV

50 cm

1.7 m



Chicane - Double Achromat Optics

300

300

1-1

BET

A_X&

Y[m

]

DIS

P_X&

Y[m

]


300

0.5

0PH

ASE_

X&Y

Q_X Q_Y

∆φx = 2π

∆φy = 2π

FODO quads:L[cm] = 50

F: G[kG/cm] = 0.322

D: G[kG/cm] = -0.364

betatron phase

H -H V H-H-V3 cells

4 cells

sextupole pair to correct vert. emittance dilutoin

Double achromat Optics



78.91030

150

50

BET

A_X&

Y[m

]

DIS

P_X&

Y[m

]


39.91030

150

50

BET

A_X

&Y[

m]

DIS

P_X&

Y[m

]


Multi-pass Linac Optics – Bisected Linac

1-pass, 1200-1800 MeV

‘half pass’ , 900-1200 MeVinitial phase adv/cell 90 deg. scaling quads with energy

mirror symmetric quads in the linac

quad gradient

quad gradient



10 cells in

2 cells out

2 cells outfootprint

-5000

-4000

-3000

-2000

-1000

0

1000

2000

3000

4000

5000

0 2000 4000 6000 8000 10000

z [cm]

x [cm]

(βout = βin and αout = -αin , matched to the linacs)

transition transition

E =1.2 GeV

40-40 S [cm] View at the lattice end

300

-300

dP/P

* 1

000,

40-40 S [cm] View at the lattice begin

300

-300

dP/P

* 1

000,

Mirror-symmetric ‘Droplet’ Arc – Optics

1300

150

3-3

BET

A_X&

Y[m

]

DIS

P_X&

Y[m

]




Linac-to-Arc – Chromatic Compensation E =1.8 GeV

‘Matching quads’ are invoked

No 900 phase adv/cell maintained across the ‘junction’

Chromatic corrections needed – two pairs of sextupoles

36.91030

150

3-3

BET

A_X

&Y[

m]

DIS

P_X&

Y[m

]

BETA_X BETA_Y DISP_X DISP_Y 720

150

3-3

BET

A_X

&Y[

m]

DIS

P_X&

Y[m

]




Linac-to-Arc − Chromatic Corrections

30-30 X [cm] View at t

80

-80

X̀[m

rad]

30-30 X [cm] View at th

80

-80

X̀[m

rad]

30-30 X [cm] View at

80

-80

X̀[m

rad]

initial uncorrected two families of sextupoles

36.91030

150

3-3

BET

A_X

&Y[

m]

DIS

P_X&

Y[m

]

BETA_X BETA_Y DISP_X DISP_Y 720

150

3-3

BET

A_X

&Y[

m]

DIS

P_X&

Y[m

]




‘Droplet’ Arcs scaling – RLA I

i = 1…4 Ei [GeV] pi/p1 cell_out cell_in length [m]

Arc1 1.2 1 2 2 10 130

Arc2 1.8 1.43 2 3 15 172

Arc3 2.4 1.87 2 4 20 214

Arc4 3.0 2.30 2 5 25 256

Fixed dipole field: Bi =10.5 kGauss

Quadrupole strength scaled with momentum: Gi = 0.4 kGauss/cm

Arc circumference increases by: (1+1+5) 6 m = 42 m

footprint

-5000

-4000

-3000

-2000

-1000

0

1000

2000

3000

4000

5000

0 2000 4000 6000 8000 10000

z [cm]

x [cm]

1ppi



RLA II

0.6 GeV/pass3.6 GeV

0.9 GeV244 MeV

146 m

79 m

2 GeV/pass

264 m

12.6 GeV

prelinac

RLA I

RLA II

• Very similar to RLA I• cells 2X as long



RLA I cell

RLA II cell

RLA I and II linac cells



‘Droplet’ Arcs scaling – RLA II

i = 1…4 Ei [GeV] pi/p1 cell_out cell_in length [m]

Arc1 4.6 1 2 2 10 260

Arc2 6.6 1.435 2 3 15 344

Arc3 8.6 1.870 2 4 20 428

Arc4 10.6 2.305 2 5 25 512

Fixed dipole field: Bi = 40.3 kGauss

Quadrupole strength scaled with momentum: Gi = 1.5 kGauss/cm

Arc circumference increases by: (1+1+5) 12 m = 84 m

footprint

-5000

-4000

-3000

-2000

-1000

0

1000

2000

3000

4000

5000

0 2000 4000 6000 8000 10000

z [cm]

x [cm]

1ppi



RLA with Two-Pass FFAG Arcs

244 MeV

0.6 GeV/pass3.6 GeV

0.9 GeV

146 m

79 m

2 GeV/pass

264 m12.6 GeV

Two regular droplet arcs replaced by one two-pass FFAG arc

Reduced beam line length, perhaps reduced costs

Simplified scheme

No need for a complicated switchyard

Non-linear and linear FFAG solutions with linear solution likely preferable

79 m

RLA with FFAG ArcsAlex Bogacz



60°

300°

simple closing of geometrywhen using similar cells

C = 302.4 m

Two-Pass FFAG Arcs

Px2Px1

Dx



Cell Matching1.2 GeV/c 2.4 GeV/c

outward inward outward inward



Dynamic Aperture

EUROnu Jan. 2011



Two-Pass Linear FFAG Arcs

Same concept as with the non-linear FFAG arcsDroplet arcs composed of symmetric FFAG cellsEach cell has periodic solution for the orbit and the Twiss functionsFor both energies, at the cell’s entrance and exit:

Offset and angle of the periodic orbit are zero Alpha functions are zeroDispersion and its slope are zero

Outward and inward bending cells are automatically matched

More elements needed for each unit cell to satisfy diverse requirements



Two-Pass Linear FFAG Arcs

Combined function magnets with dipole and quadrupole field components only

Much greater dynamic aperture expected than in the non-linear caseEasier to adjust the pass length and the time of flight for each energyEasier to control the beta-function and dispersion valuesInitial beta-function values chosen to simplify matching to linacMuch simpler practical implementation without non-linear fields



Linear FFAG: Linear Optics of Arc 1 Unit Cell Path lengths adjusted to give time of flight difference of one period of RF1.2 GeV/c 2.4 GeV/c



Multi-pass linac Optics w/ FFAG arcs

1 0 0 00 1 0 00 0 1 00 0 0 1

M

− =

−

355.5520

800

50

BET

A_X&

Y[m

]

DIS

P_X&

Y[m

]

BETA_X BETA_Y DISP_X DISP_Y 355.5520

800

50

BET

A_X&

Y[m

]

DIS

P_X&

Y[m

]


1.2 GeV0.9 GeV 3.0 GeV2.4 GeV1.8 GeV 3.6 GeV

Arc 1βx = 8 m βy = 2 m

αx = 0 = αy

M


αx = 0 = αy


αx = 0 = αy

Arc 2βx = 10 m βy = 3 m

αx = 0 = αy

M M M



RLA I & II – near term plans

determine dynamic aperture

determine error sensitivity

examine & optimize chromatic tune dependence

match RF phasing in linac and arcs

create a magnet specification for costing

FFAG arc design:

Single pass arc design:straight-forward continuation of design of RLA I & II

determine RF phasing along linac (v<c) & Adjust arc timing

fill in details of transfer lines

complete component lists for costing

continue linac simulations into RLAs for matching, heat & radiation loads



Non-Linear FFAG: 1.2 GeV/c Linear Optics of Arc 1 Unit Cell

Combined-function bending magnets are used1.2 GeV/c orbit goes through magnet centersLinear optics controlled by quadrupole gradients in symmetric 3-magnet cellDispersion compensated in each 3-magnet cell

3-magnet cell MAD-X (PTC)



sextupole and octupole components

Non-Linear FFAG: 2.4 GeV/c Linear Optics of Arc 1 Unit Cell

Unit cell composed symmetrically of three 3-magnet cellsOff-center periodic orbitOrbit offset and dispersion are compensated by symmetrically introducing sextupole and octupole field components in the center magnets of 3-magnet cells

symmetric unit cell

MAD-X (PTC)



Non-Linear FFAG: Linear Optics of Arc 2 Unit Cell Same concept as 1.2 GeV/c linear optics of Arc #11.8 GeV/c 3.0 GeV/c



Linear FFAG: Linear Optics of Arc 2 Unit Cell Path lengths adjusted to give equal times of flight for the two momenta1.8 GeV/c 3.0 GeV/c

Progress on the Linac and RLAscasa.jlab.org/.../2011/EUROnu-2011/kbb2L.euronu.pdf, 2011. Linac –...

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Transcript of Progress on the Linac and RLAscasa.jlab.org/.../2011/EUROnu-2011/kbb2L.euronu.pdf, 2011. Linac –...