SPL to PS2 transfer line and PS2 injection requirements

W. Bartmann, Ch. Hessler, B. Goddard, M. Eshraqi, M. Meddahi, A. Lombardi

3rd SPL Collaboration Meeting, 11th - 13th Nov 09

2

PS2 and Transfer Lines Overview

850 900 950 1000 1050 1100 1150 1200 1250 1300 1350

2150

2200

2250

2300

2350

2400

2450

2500

2550

2600

2650

~ 11 m

P S 2

T T 11

T T 10 (new )

S P S

T T 10 (o ld )

T T L1

T I 2

T T E A

T D 1

based on PS2version from17. Dec. 2008

SPL

3

Driving Parameters for TTL1

LP-SPL LP-SPL-5G HP-SPL

Kinetic energy [GeV] 4 5 5

Repetition rate [Hz] 2 2 50

Pulse length [ms] 1.2 1.2 0.4

Average pulse current [mA] 20 20 40

Beam power [MW] 0.192 0.24 4

Max. fract. loss [m-1](due to Lorentz stripping)assuming max. Ploss =0.1 W/m

5.2e-7 4.17e-7 2.5e-8

Max. dipole field [T] 0.115 0.0950 0.0858

Min. rho [m] 141 206 228

Expression fractional loss from A.J. Jason et al, IEEE Trans.Nucl.Sci. NS-28, 1981http://ieeexplore.ieee.org/stamp/stamp.jsp?arnumber=4331890&isnumber=4331887

4

Beam Line Geometry

1 0 0 m

S P L en d p o in t h o rizo n ta lb en d in gm ag n e ts

v e rtica lb en d in gm ag n e ts

in jec tio n ch ican e m ag n e tp o in t C q u ad ru p o le s

b eam

ach ro m a t 1 ach ro m a t 2 ach ro m a t 3 ach ro m a t 4

first part compatible with HP-SPL, second part only compatible with LP-SPL @ 4 GeV

second part can be compatible with LP-SPL @ 5 GeV if 7.2 m (instead of 5.75 m) long dipoles are used

large slope of 8.1%

5

Optics Simulation

SPL PS2

6

Optics Simulation

7

Aperture Calculation

max

1.11.1,

cop

pDNyx phys

N = 6co = 5 mm

beam envelope:

s [m]

x,y [m]

8

Multi-particle Simulations

Simulation code: TraceWin

Beam current: 62 mA

Emittance growth (H/V): 23% / 2%

Energy spread increase: from ±1.5 MeV to ±7 MeV

M. Eshraqi

9

Trajectory Correction

100 uncorrected trajectories:

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Trajectory Correction: Results

Each quadrupole equipped with a H/V monitor 2 quadrupoles out of 3 equipped with a corrector

Correction OK

11

Outlook TTL1

Complete new PS2 LSS1 layout to disentangle injection/extraction region

New TTL1 version (work in progress):

12

Parameters for ISOLDE/EURISOL Beam Lines

ISOLDE EURISOL

LP/HP-SPL LP-SPL HP-SPL

Kinetic energy [GeV] 1.5 2.5 2.5

Repetition rate [Hz] 1.25 1.25 50

Pulse length [ms] 1.2 1.2 0.8

Average pulse current [mA] 20 20 40

Beam power [MW] 0.045 0.075 4

Max. fract. loss [m-1](due to Lorentz stripping)assuming max. Ploss =0.1 W/m

2.22e-6 1.33e-6 2.5e-8

Max. dipole field [T] 0.254 0.172 0.149

Min. rho [m] 29.5 64.1 74.0

Expression fractional loss from A.J. Jason et al, IEEE Trans.Nucl.Sci. NS-28, 1981http://ieeexplore.ieee.org/stamp/stamp.jsp?arnumber=4331890&isnumber=4331887

Extraction from SPL to ISOLDE

Input parameters p+ beam

1.4 GeV p+, Br = 7.14 Tm

42 kW

0.29 T maximum bending field (0.1 W/m)

0.65 m cryomodule radius

Same radius assumed for Warm-Cold transition

Results Use 0.22 T dipole, 4 m long, 123 mrad

0.15 m clearance at cryomodule/W-C transition

Pulsed dipole, 1.25 Hz repetition rate

Stripping foil outside the extraction region

Losses in extraction dipole N/N0 ~1e-7 (0.02 W/m) from stripping foil, 4.3 e-5 (1.8 W)

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Layout for 1.4 GeV p+ extraction

13 m

9 m

CryomoduleW-C transition

W-C transition

2 m

Cryomodule

0.5 m

0.22 T

0.65 m

0.15 m4 m

6.5 m

Extraction dipole

123 mrad

to foil

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Extraction from SPL to EURISOL

Input parameters:

H- beam

2.5 GeV H-, Br = 11.03 Tm

6 MW (!)

0.15 T maximum bending field (0.1 W/m)

0.65 m cryomodule radius

Same radius assumed for Warm-Cold transition

Results

Use 0.15 T dipole, 8 m long (!), 109 mrad

0.15 m clearance at cryomodule/W-C transition

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Layout with 9m available drift

13 m

9 m

CryomoduleW-C transition

W-C transition

2 m

Cryomodule

0.5 m

0.15 T

0.49 m

8 m

6.5 m

Extraction dipole

109 mrad

0.5 m

16

Does not work!!

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Layout with minimum possible drift

16.4 m

12.4 m

Cryomodule

WCT WCT

0.5 m

Cryomodule

0.5 m

0.15 T

2.75 m

7.2 m

Extraction dipoles

112 mrad

0.5 m 0.15 m

0.15 m

2 m

5.2 m

0.43 m

Length/Height of WCT for 13 m period

13 m

12.1 m

Cryomodule

WCT WCT

0.9 m !!!

Cryomodule

0.5 m

0.15 T

3.05 m

6.5 m

Extraction dipoles

124 mrad

0.15 m

0.5 m

0.55 m

0.15 m

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Stripping foil thickness optimisation

0 500 1000 1500 2000 2500 3000 3500 4000 4500 500010

-6

10-5

10-4

10-3

10-2

10-1

100

Foil thickness [ug/cm2]

Loss

fra

ctio

n

Total loss

Elastic scattering

Inelastic scatteringUnstripped H-

Unstripped H0

large angle single Coulomb scattering

0 500 1000 1500 2000 2500 3000 3500 4000 4500 500010

-6

10-5

10-4

10-3

10-2

10-1

100

Foil thickness [ug/cm2]

Loss

fra

ctio

n

Total loss

Elastic scattering

Inelastic scatteringUnstripped H-

Unstripped H0

large angle single Coulomb scattering

2.5 GeV3.2x10-5 loss6 MW 192 W

1.4 GeV4.3x10-5 loss42 kW 1.8 W

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Loss minimum for a foil thickness of 1200 – 1300 ug/cm2

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PS2 Injection Requirements

Potential H- injection issues for Foil stripping Longitudinal Painting constraint on dispersion in injection region with Δε from

dispersion mismatch Heating: Injection repetition rate, intensity Transverse emittance beam size on foil Uncontrolled losses :

Halo – collimation in TL? Kinetic Energy significantly less than 4 GeV scattering, aperture, …

Potential H- injection issues for Laser stripping Longitudinal Painting large momentum range would dramatically increase required

laser power Bunch length increases Laser average power, optimisation to study Energy jitter increases range of frequencies to be swept 100 keV jitter OK Trajectory jitter

Match laser and ion beam as much as possible, vertically more stringent – more laser power required (to get necessary power density)

Kin Energy significantly less than 4 GeV Laser power, emittance growth

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Energy Jitter

Need divergence in Laser beam to cover the spread of exciting resonance frequencies due to Doppler broadening

Laser frequency range is determined by effective momentum spread

To have no big effect, need energy jitter one order below initial momentum spread ΔEkin = 10-4 GeV

Laser stripping much more difficult for significantly reduced kinetic energy (e.g. 3.5 GeV) – can only access n=2 state with 1064 nm which means huge emittance growth in last magnetic stripping step

Den at 4 GeV

1064 nm

Conclusion TTL1

TTL1 design: First part compatible with all SPL versions

Second part only with LP SPL (4 GeV), if LEP yokes not used but longer magnets also for LP SPL (5 GeV)

8.1 % slope civil engineering!

Multiple particle simulations Emittance growth (H/V): 23% / 2%

Energy spread increase: from ±1.5 MeV to ±7 MeV

Trajectory correction OK

Outlook: TTL1 optics studies ongoing because of new PS2 injection region design

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Conclusion Extraction and PS2 Injection

Extraction to ISOLDE OK

Extraction to EURISOL Not feasible within constraints!

2 possibilities:

Opening up distance between cryomodules to 16.4 m and reducing radius of WC transition to 43 cm

Within given 13 m, reduce WC transition length to 90 cm and radius to 55 cm

PS2 Injection

Study on H- injection is work in progress…

Significantly reduced energy makes injection much more difficult!

Large momentum range and bunch length increase Laser power need to optimise

Energy jitter of 100 keV OK

Losses in injection region Halo collimation in TL?

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Back up slides

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Beam and Twiss Parameters

x plane y plane

norm. 1s emittance [µm] 0.351 0.350

beta [m] 106.5 117.3

alpha -0.055 -1.352

dispersion [m] 0 0

dispersion derivative 0 0

SPL end point (Source: M. Eshraqi):

x plane y plane

beta [m] 15 15

alpha 0 0

dispersion [m] -0.4 0

dispersion derivative 0 0

Injection point (Source: W. Bartmann):

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Trajectory Correction: Assumed Errors

Quadrupole displacement errors: Gaussian distribution in x/y with s = 0.2 mm, cut at 3s

Dipole field errors: Gaussian distribution of deflection with s = 10 µrad, cut at 2s (→ relative field error of 5e-4)

Dipole tilt errors: Gaussian distribution with s = 0.2 mrad, cut at 4s

Monitor errors: Flat random distribution of ±0.5 mm in both planes

Injection error: Gaussian distribution of position / angle with s = 0.5 mm / 0.05 mrad, cut at 2s

Monitor failure probability: 5%