Staging and Energy upgrade scenarios

K.Kubo

Staging?

BDS

ML

BDS

ML

No cavitiesFull

Sparse cavities (e.g. every other place)

A

B

A will be better from beam dynamics, preserving low emittance beam.But, how important?

If we want to start operation with half cavities, how to distribute them?

Simulation for Final Ebeam 125 GeV

BDS

ML

BDS

ML

No cavitiesFull

Sparse cavities (every other place)

A

B

No cavities

15 GeV 125 GeV

BDS

ML

Low gradient (all cavities installed)

C (for comparison)

No cavities

Same Optics

Vertical emittance along the linac, mean of 100 random seeds.“Standard errors” (except Q roll) and Dispersion Matching Steering

125 GeV C

2 10-8

2.1 10-8

2.2 10-8

2.3 10-8

2.4 10-8

2.5 10-8

2.6 10-8

2.7 10-8

0 2000 4000 6000 8000 1 104

mean of 100 seeds

125 GeV Low Gradient125 GeV Cav. 1st part125 GeV Sparse Cav. 250 GeV

mea

n y (

m)

s (m)

125 GeV A

125 GeV B

250 GeV

No significant difference between A (fill cavities in 1st part) and B (sparsely distributed cavities)

Error RTML and ML Cold with respect to

Quad Offset 300 μm cryo-module

Quad roll 300 μrad design

RF Cavity Offset 300 μm cryo-module

RF Cavity tilt 300 μrad cryo-module

BPM Offset (initial) 300 μm cryo-module

BPM Resolution 1 μm ---

Cryomoduloe Offset

200 μm design

Cryomodule Pitch 20 μrad design

“Standard” Error in ML

2 10-8

2.01 10-8

2.02 10-8

2.03 10-8

2.04 10-8

2.05 10-8

2.06 10-8

2.07 10-8

0 2000 4000 6000 8000 1 104

Ebem

=125 GeV, low gradient (C)

Ebeam

=125 GeV, sparse cavities (B)

Ebeam

=125 GeV, cavities in first part (A)

Ebeam

=250 GeV

Mea

n

-cor

rect

ed y

(m

)

s (m)

Vertical emittance along the linac, mean of 100 random seeds.“Standard errors” (except Q roll) and Dispersion Matching SteeringZero bunch charge (no wakefield)

125 GeV C

125 GeV A

125 GeV B

250 GeV

Most emittance growth is from wakefield.Further correction for wakefield (wake bump) can reduce emittance close to this figure.

Comparison of different choices for 125 GeV and 175 GeV250 GeV for comparisonWith and without wakefield

0

0.1

0.2

0.3

0.4

0.5

125 GeV

sparce cav

175 GeV

sparce cav.

125 GeV

Cav in 1st part

175 GeV

Cav in

1st part

125GeV

low grad.

175 GeV

low grad

250 GeV

N=2E10

N=0M

ean

y/

y0

Mean (dot) and Standard dev. (bar) of 100 seeds

No significant difference between A (fill cavities in 1st part) and B (sparsely distributed cavities)

Energy upgrade (ECM 500 -> 1000 GeV)

• Review of old story.

• FODO or FOFODODO lattice?

• 3 or 4 modules/quad?

BC (5-15 GeV)ML (15-25 GeV)Special mag. ML (25-250 GeV)

New part (25-275GeV)

Move to upstream Keep for275 – 500 GeV

Upgrade Ebeam from 250 to 500 GeV

3 modules/quad FODO

Strengths of quads in E_beam >　 250 = Strength at 250 GeV Or, K1 ~ 1/E_beam

3 modules/quad FOFODODO

Strengths of quads at E_beam = 500 = Strength at 250 GeV K1(E_beam > 250 GeV) = ½ K1(E_beam < 250GeV)

Weak magnets for Ebeam 275 – 500 GeV

FOFODODO can make dispersion in downstream part small.Loose tolerance of BPM scale error in DMS correction.

Simulation results of DFS with “standard” static errors

2 10-8

2.2 10-8

2.4 10-8

2.6 10-8

2.8 10-8

3 10-8

0 5000 1 104 1.5 104 2 104

FDFD BPM scale error 0FDD BPM scale error 0

<

y,

-cor

rect

ed>

(m

)

s (m) average of 40 seeds

Simulation results of DFS with “standard” static errors + BPM Scale error 5%

average of 40 seeds

2 10-8

2.5 10-8

3 10-8

3.5 10-8

4 10-8

4.5 10-8

5 10-8

0 5000 1 104 1.5 104 2 104

FDFD, BPM scale error 5%

FFDD BPM scale error 5%

<

y,

-cor

rect

ed>

(m

)

s (m)

SUMMARY

• Two staging scenarios (fill first part and sparsely distribute) are both OK.– “Fill first part” is better, but probably not

important.• Upgrade scenarios from 500 GeV ECM to 1TeV

in TDR is OK – FOFODODO lattice in high energy part, with weak

quad strength.