SPEAR3 Chicane, Accelerator Physics Update, February 10, 2005

• Electron optics design review August 11, 2004– “… no show stoppers. However, …”

• Additional electron dynamics simulations– Add insertion devices to computer model– Add damping and smaller ID gaps

• Scraper measurements– Lifetime vs. ID gap study– Injection loss vs. ID gap study

• Magnetic tolerance specifications

J. Corbett, M. Cornacchia, R. Hettel, Y. Nosochkov, G. Portmann, T. Rabedeau, A. Ringwall, J. Safranek,

J. Sebek, A. Terebilo, M. Yoon

Chicane

BL13

BL12

7.6 meters

2.2 m 2.2 m

RF

4.8 m matching straight3 m

standard straight

East Pit

Baseline optics

Chicane optics

matching straight, y = 4.8 m

matching straight, y = 2.5 m

long straight, y = 10 m

long straight, y = 1.6 m

Electron dynamics• 3D harmonic oscillator

• Nonlinear elements: sextupoles, wigglers

• Limit to dynamic stability: dynamic aperture.

• Need sufficient aperture for lifetime and injection

))(cos()(

)',,',()(''

ssax

yyxxfxsKx

Dynamic aperture required for injection

Stored beam Injected beam

sept

um m

agne

t iro

n

Dynamic aperture simulations(from previous review)

Baseline optics Chicane optics

-0.02 -0.01 0 0.01 0.020

1

2

3

4

5

6x 10

-3

x [m]

y [m

]

Baseline Optics :DA + 5mm PA

On Energy3%

-0.02 -0.01 0 0.01 0.020

1

2

3

4

5

6x 10

-3 Double Waist Asymmetric Chicane Optics :DA + 5mm PA

x [m]y

[m]

On Energy3%

•Did not include wigglers

•Did not include damping

•Course grid of initial conditions

LIMITATIONS:

-0.03 -0.02 -0.01 0 0.01 0.02 0.030

0.005

0.01

0.015

X0 [m]

Y0 [

m]

New simulations including wigglers and damping

-0.025 -0.02 -0.015 -0.01 -0.005 0 0.005 0.01 0.015 0.02 0.0250

1

2

3

4

5x 10

-3

X0 [m]

Y0 [

m]

Baseline with IDs, DAPA

On Energy Best/Worst

On Energy Mean3% Best/Worst

3% Mean

-0.025 -0.02 -0.015 -0.01 -0.005 0 0.005 0.01 0.015 0.02 0.0250

1

2

3

4

5x 10

-3 DW with IDs, DAPA

X0 [m]

Y0 [

m]

On Energy Best/Worst

On Energy Mean3% Best/Worst

3% Mean

Baseline optics

Chicane optics

High-density tracking & Tune mapsC

hic

an

e o

ptic

sB

ase

line

op

tics

BL12 gap; aperture scans

• BL9 aperture scans– Lifetime vs. vertical orbit– Lifetime ~ constant over 4 mm– Systematic errors– Re-measure with scrapers,

11/2004

• BL12 gap, conservative– 12 – 2 = 10 mm at BL9– Scales to 6.2 mm at BL12

• BL12 gap, aggressive– 12 – 4 = 8 mm at BL9– Scales to 5.0 mm at BL12

-5 -4 -3 -2 -1 0 1 2 3 4 50

5

10

15

20

25

30

35

40

45

50

Beam Bump Position [mm]

Life

time

[Hou

rs]

BL 9, Vertical Bump, 18.0 mA, 24 Bunches, Ion Pumps On, 4/20/04

Orbit bump at BL9 12 mm aperture.

-10 -8 -6 -4 -2 0 20

5

10

15

20

25

30

35

40

mm

hour

s

~100 mA, 280 bunches (Scraper y 2005-02-02 00-43-19)

measuredfit

4.7 mm

TBC 1111

b

bunch

totT

totB

totC

IfN

I

If

yI

)apertureE(*

)apertureE(*pressure

*aperturey*pressure 22

Five fit parameters:

ringbeam

TBC

yy ,

,,, 000

Measured lifetime vs. vertical aperture

More tracking with apertures

-0.02 -0.01 0 0.01 0.020

1

2

3

4

5x 10

-3 Baseline, on-energy

x [mm]

y [m

m]

max

min

mean

5.09 mm BL12 gap

6.36 mm BL12 gap

-0.02 -0.01 0 0.01 0.020

1

2

3

4

5x 10

-3

x [mm]

y [m

m]

Baseline, 3% off-energy

6.36 mm BL12 gap

5.09 mm BL12 gap

-0.02 -0.01 0 0.01 0.020

1

2

3

4

5x 10

-3 Chicane, on-energy

x [mm]

y [m

m]

-0.02 -0.01 0 0.01 0.020

1

2

3

4

5x 10

-3 Chicane, 3% off-energy

x [mm]

y [m

m]

Measured injection vs. vertical aperture

0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 5.50

0.5

1

1.5in

ject

ion

effi

cie

ncy

[arb

. un

its]

scraper vertical half aperture [mm]

BL12 gap [mm]5 5.5 6

BL12 field specifications• On-axis (x=y=0) specifications, normal, bn, and skew, an

– Integrated quadrupole < 50 G– Integrated sextupole < 75 G/cm– Integrated octupole < 40 G/cm2

• Off-axis specifications– 1st integral of By < 100 + 50*|x| G*cm, |x|<2.5 cm– 1st integral of Bx < 40 + 75*|x| G*cm, |x|<2.5 cm– 2nd integral of By < 1.5e4+1e4*|x| G*cm2, |x|<2.5 cm. – 2nd integral of Bx < 5e3+1e4*|x| G*cm2, |x|<2.5 cm – 1st integral deriv. < 50+150*|x| G; |x|<2.5 cm,

• Peak field transverse roll-off – dBy/dx < 11000+5500*|x| G/cm, |x|<2.5 cm (BL12)– d2By/dx2 < 15000+20000*|x| G/cm2, |x|<2.5 cm (BL12)

• Accelerator physics group will review fields, once the ID is designed.• Accelerator physics group will review magnetic measurements plan.

dzBx yx,

nnn iyxiba ))(()dziB -(B yx