July 23, 2005 Luminosity improvement plan 1

Plan for L/I Improvement

D. Rubin

July 23, 2005 Luminosity improvement plan 2

Energy dependence of solenoid compensation

Solenoid on equilibrium beam size is~ twice solenoid off size

July 23, 2005 Luminosity improvement plan 3

Compensation scheme

• PM, Q1, Q2 are rotated 4.5 degrees about axis, designed to compensate 1.5T solenoid at 5.3 GeV• Skew quad coils are superimposed on Q1 and Q2 for fine tuneing and energy reach• Skew quad 3, is third component in “3-pair” compensation scheme• The first bending magnet is immediately beyond skew quad 3

Q2 Q1PM

CLEO solenoid

Skew quad 3 sk_q03w

sk_q03e

July 23, 2005 Luminosity improvement plan 4

Compensation schemeConstraints:

• 4X4 matrix from sk_q03w through sk_q03e (T3-3) is block diagonal• Matrix from sk_q03w to IP has the form

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T =M m

n N

⎛

⎝ ⎜

⎞

⎠ ⎟ and

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n =0 0

~ ~

⎛

⎝ ⎜

⎞

⎠ ⎟

Requires 3 antisymmetrically placed pairs of skew elements namely sk_q03, q1, and q2Equivalently T3-3 is block diagonal and

c11=c12=c22= 0 at the IP for the full turn matrix3-pair compensation scheme

There are no bending magnets within the compensation region

July 23, 2005 Luminosity improvement plan 5

Qx=0.52Qy=0.58Qz=0.089

Separators offBegin tracking outsideOf compensation regionXinit =2mm

=0.0 =0.00084CESR-c 3 pair compensaton

July 23, 2005 Luminosity improvement plan 6

Qx=0.52Qy=0.58Qz=0.089

Separators offBegin tracking outsideOf compensation regionXinit =2mm

=0.0 =0.00084No solenoid

July 23, 2005 Luminosity improvement plan 7

Solenoid Compensation

• 3-pair compensation– Energy dependence of coupling parameters

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ΔEE

= 0.00084 ⇒ Cij ~ 0.6%

July 23, 2005 Luminosity improvement plan 8

Q2 Q1PM

CLEO solenoid

Compensating solenoid

Skew quad

July 23, 2005 Luminosity improvement plan 9

Compensation with anti-solenoid

Strategies• Set ∫Bantidl = -∫Bcleodl ~ 2(1.85T)(0.95m) = 2(1.76T-m)

a) Use 3-pair constraints (PM angle fixed at 4.5 degrees)b) 4-pair constraints where PM angle is fourth degree of freedom [4-pair => transport to IP is block diagonal]

• Minimize energy dependence of C3-3 and impose• 3 pair constraints

T3-3 maps through insert from 3w to 3E and

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U =A 0

0 B

⎛

⎝ ⎜

⎞

⎠ ⎟

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T3−3 = RUR−1

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R =γI C3−3

−C3−3+ γI

⎛

⎝ ⎜ ⎜

⎞

⎠ ⎟ ⎟

•What is the global coupling, insertion coupling, and luminosity for each configuration

July 23, 2005 Luminosity improvement plan 10

Compensation with anti-solenoid

3 pair, no antisol

3 pair, antisol

4 pair, antisol and pm tilt

3 pair, antisol.Minimize dC/dEwith antisol andPM tilt

July 23, 2005 Luminosity improvement plan 11

July 23, 2005 Luminosity improvement plan 12

Luminosity vs energy derivatives of C3-3

for different compensation configurations

July 23, 2005 Luminosity improvement plan 13

Compensation with anti-solenoid

1.No solenoid2.Minimize dC3-3

& anti-sol3.4-pair & anti-sol4. 3-pair & anti-sol5. CESR-c, 3-pair & no anti-sol

July 23, 2005 Luminosity improvement plan 14

Compensation with anti-solenoid

Effectiveness of anti-solenoid depends on details of compensation scheme

Consider•Energy dependence of full turn coupling parameters at IP•Energy dependence of insertion coupling parameters

Have yet to define configuration that reproduces solenoid off performance

July 23, 2005 Luminosity improvement plan 15

Compensation with anti-solenoid

Simulation indicates ~50% increase in specific luminosity with anti-solenoid

To achieve that gain implies 0.2% coupling (sigma_y = 1 micron)

What are the appropriate design criteria?

Optics with minimum dC3-3/dE is no different from 4-pair compensation with 1.9deg PM tilt

Optics with minimum dC3-3/dE => field of anti-solenoid X ~ 2

Is it possible to achieve equivalent of no solenoid?

Installation January 2006

July 23, 2005 Luminosity improvement plan 16

July 23, 2005 Luminosity improvement plan 17

Anti-solenoid in IR

July 23, 2005 Luminosity improvement plan 18

Reduced momentum compaction

p =0.049, Qz = 0.042 => l = 12mm

July 23, 2005 Luminosity improvement plan 19

Longitudinal emittance

• Element M inserted in ring opposite IP– Then l = 12mm => Qs= 0.049 or Qs =0.089 => l = 7.3mm

July 23, 2005 Luminosity improvement plan 20

Reduced momentum compaction optics

July 23, 2005 Luminosity improvement plan 21

Reduced momentum compaction optics

Injection Pretzel must be constrained so that electrons closed orbit is near injection point

July 23, 2005 Luminosity improvement plan 22

Summary

•Reduction in energy dependence with anti-solenoid 25 - 40% increase in luminosity at low current Installation January 2006

•Optics with reduced momentum compaction promises payoff at higher current and subject of ongoing investigation

Caution: If we are successful reducing 0 current beam size and increasing limiting tune shift then we become more sensitive to

RF phase noiseResidual couplingVertical dispersionpower supply ripple, etc.

July 23, 2005 Luminosity improvement plan 23

Wiggler Beam Measurements

-Injection

1 sc wiggler (and 2 pm CHESS wigglers) -> 8mA/min

6 sc wiggler -> 50mA/min

1/ = 4.5 s-1

1/ = 10.9s-1

July 23, 2005 Luminosity improvement plan 24

Wiggler Beam Measurements 6 wiggler lattice

-Injection

30 Hz 68mA/80sec 60 Hz 67ma/50sec

July 23, 2005 Luminosity improvement plan 25

Wiggler Beam Measurements

-Single beam stability

1/ = 4.5 s-1 1/ = 10.9s-1

2pm + 1 sc wigglers 6 sc wigglers