status on an ir design for a super-b factory

1Super-B Factory WorkshopApril 20-23, 2005

Super-B IR designM. Sullivan

Status on an IR Designfor a

Super-B Factory

M. Sullivan

for the

Super-B Factory WorkshopHawaii

April 20-23, 2005



Outline

•General B-factory parameters

•IR parameters

•Synchrotron Radiation Issues

•Present IR design

•Summary and conclusions



PEP-III Super B parameters for a 11036 Luminosity

Super BLER energy 3.5 GeVHER energy 8.0 GeVLER current 23.0 AHER current 10.1 A

y* 1.5 mm

x* 15 cm

X emittance 40 nm-radEstimated y

* 1.7 m

Bunch spacing 0.315 mNumber of bunches 6900Collision angle 14 mradsBeam pipe radius 2.5 cm

Luminosity 11036 cm sec



Detector acceptance down to 300 mrad angle – forward and backward

Beam pipe radius of 2.5 cm

Translates to ±10 cm of active beam pipe

The Q2 septum is at 2.5 m

IR design parameters



PEP-II IR design ended up with ~10 /crossing – which is 2.39 Ghz – rate on the detector beam pipe (11 krad/yr)

Background levels from SR can be no more than factor of 100 to 1000 times higher than PEP-II before radiation doses get too high (occupancy may be OK for pixelated detector)

Make all of the SR radiation from local bends in the beam miss nearby surfaces (power from the high current beams is too high for local absorption)

SR constraints and limits…



0

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-300-5 5m

cm

Super B-factory IR

E36_2_5M_8_RL

M. Sullivan, Jan. 16, 2004

QD1QD1

QF2

QF2

QD4

QF5

QD4

QF5

HER

LER

83 kW

11 kW

40 kW

200 kW

Current baseline design



physics window +/- 10 cm

2.5 cm radius beam pipe

e36 B-factory IR +/- 14 mrads RevD

M. Sullivan Apr 16, 2005B3$E36_2_5M_8D_RL

-1 -0.5 0 0.5 1

0

2

4

-2

-4

cm

m



Version /X /s WattsPEP-II design 10 2.39e9 1.4e-5 11 krad/yrBaseline design

HER 4.65e4 4.37e13 0.86LER 5.71e4 5.37e13 0.01

Offset Q4 10 mm & offset Q2 12 mmHER 141 1.33e11 3.1e-4LER 244 2.29e11 1.1e-3

8 instead of 10HER 140 1.32e11 2.8e-4

Tail #1HER 5.8 5.45e9 1.3e-5LER 9.6 9.03e9 4.2e-5

Tail#2HER 0.10 9.40e7 2.2e-7LER 0.15 1.41e8 6.8e-7

No tailsHER 6.9e-14 6.49e-5 1.5e-19LER 1.3e-11 0.012 6.9e-17

SR backgroundsphotons > 4keV on the physics window beampipe



Vertical beam focusing (side view)

Horizontal beam focusing (plan view)

(a)

(b)

Vertical plane is not as hard

Horizontal plane is more difficult so try to steer the Q5 radiation away from the beam pipe


Super-B IR designM. Sullivane36 B-factory IR +/- 14 mrads RevD

0

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cm

M. Sullivan Apr 16, 2005B3$E36_2_5M_8D_RL

200 kW40 kW

13 kW

83 kW3 kW

11 kW

QF5QD4 QF2

QD1QD1

QF2

QD4

QF5

LER

HER



Bending power vs quadrupole power

Magnet Bending pwr Quadrupole pwr

HER beam (10A)Up Q5 0 1672 WUp Q4 12800 W ~3000 W

LER beam (23 A)Up Q2 3433 W 46 W



What is the correct beam tail distribution?

•The present PEP-II design is insensitive to the tail distribution since the SR background is dominated by local bending fans. This allowed us to assume a conservative (high) tail particle density

• The PEP SuperB design minimizes local beam bending and hence the beam tail distribution becomes more important

•Note: the background from SR comes only from the x plane



10 15 20 25 30 355

100 100

10-3

10-6

10-9

10-3

10-6

10-9

Beam Sigmas

Y plane

X plane beam tails

PEP-II design beam tails

Tail #1

Tail #2

Beam Tail Distributions

M. Sullivan Apr. 17, 2005

Gaussian beam profile



We have made progress on a PEP SuperB interaction region design with a luminosity of 11036

Synchrotron radiation backgrounds look managable. Much more work needs to be done….

Minimal beam bending leads to a design that is sensitive to the beam tail distributions, …

Perhaps we can learn more about the correct beam tail distributions from the present B factories.

Summary and Conclusions



Backup slides



KEKB Upgrade Plans

Now Upgrades SuperKEKBLER energy 3.5 3.5 3.5 GeVHER energy 8.0 8.0 8.0 GeVLER current 1.38 2.0 9.4 AHER current 1.05 1.1 4.1 A

y* 6.0 6.0 3.0 mm

x* 58 58 15 cm

X emittance 20 20 33 nm-radEstimated y

* 2.2 2.2 2 m

Bunch spacing 2.4 2.4 0.6 mNumber of bunches 1284 1284 5018Collision angle 11 crab 15 (crab) mradsBeam pipe radius 2.0 1.5 1-2 cm

Luminosity 1.061034 2-31034 2-61035 cm sec



LER radiative gammas

0.511.5

22.5

3

LER radiative bhabhas

HER radiative gammas

7654

0.5

1

2

3

HER radiative bhabhas

KEKB Interaction Region

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cm

HER

LER

8 GeV

3.5 GeV

M. Sullivan Nov. 9, 2004 B3$KEK2_IR_RADBHA

Detector

Detector

CSL CSR

QCSL QCSR

CSL CSR

QCSRQCSL

Q1EL

Q1ER

Q2PL

Q2PR



0.5

11.5

22.5

3

LER gammas

0.5

12

3

4 5

6 7

HER gammas

Super KEKB IR

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M. Sullivan Nov. 13, 2004B3$_SUPER_KEK_RADBHA

HER

LER

8 GeV

3.5 GeV

Detector

QCSRQCSL

QC1LEQC2LE

QC2LP

QC1RE

QC2RE

QC2RP

Detector



87.57

6.56

5.5

4

3.532.5

21.51

0.5

4.55

HER Radiative Bhabhas

32.5

2 1.51

0.5

LER Radiative Bhabhas

-7.5 -5 -2.5 0 2.5 5 7.5

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cm

M. SullivanFeb. 8, 2004API88k3_R5_RADBHA_TOT_7_5M

3.1 G

eV

3.1 G

eV

9 GeV

9 GeV

PEP-II Radiative Bhabhas



0.51

1.52

2.53 3.5

4

4.5

5

5.56

6.577.5

HER radiative bhabhas

HER radiative gammas

0.511.5

2

2.53

LER radiative bhabhas

LER radiative gammas

e36 B-factory IR +/- 14 mrads

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cm

M. SullivanFeb 24, 2004

B3$E36_2_5M_8_RL_RADBHA

status on an ir design for a super-b factory

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