SuperB and SuperKEKB*

Y. OhnishiKEK

July 3, 2008

* SuperKEKB is the KEKB upgrade in the framework of the KEK roadmap

1

Collaboration of INFN-KEK

• SuperB (INFN Super B(Flavor)-Factory)– Beam-beam issues (simulation work) – Lattice issues (dynamic aperture, IR design)– Coherent synchrotron radiation(CSR) calculations

• Crab waist study at DANE– Commissioning of machine– Beam-beam issues (simulation work)– Optics calculations (dynamic aperture)– (Electron-cloud issues)

2

SuperB Accelerator CDR Contributors

• M. E. Biagini, M. Boscolo, A. Drago, S. Guiducci, M. Preger, P. Raimondi, S. Tomassini, C. Vaccarezza, M. Zobov (INFN/LNF, Italy)

• Y. Cai, A. Fisher, S. Heifets, A. Novokhatski, M.T. Pivi, J. Seeman, M. Sullivan, U. Wienands (SLAC, US)

• T. Agoh, K. Ohmi, Y. Ohnishi (KEK, Japan)

• I. Koop, S. Nikitin, E. Levichev, P. Piminov, D. Shatilov (BINP, Russia)

• A. Wolski (Liverpool University, UK)

• M. Venturini (LBNL, US)

• S. Bettoni (CERN, Switzerland)

• A. Variola (LAL/Orsay, France)

• E. Paoloni, G. Marchiori (Pisa University, Italy)

from M. Biagini, SuperB 2008 meeting 3

Comparison of Machine Parameterssymbol SuperB SuperKEKB unit

E 4.0 7.0 3.5 8.0 GeV

C 1.8 3.02 km

I 1.85 1.85 9.4 4.1 A

nb 1251 5018

N/bunch 5.5 11.8 5.1 x1010

x 2.8 1.6 12 nm

y/x 0.4 0.5 %

x* 35 20 200 mm

y* 0.22 0.39 3 mm

z 5 3 mm

x* 48 30 to 0 mrad

x 0.0043 0.0025 0.27

y 0.15 0.30

RF Power 17 64 MW

L 10 5.5 x1035 cm-2s-14

Two Approaches

5

€

L∝1

εxβ x*εyβ y

*

€

L∝N+N−nbεxβ x

*εyβ y*

€

x →εx10

εy →εy10

β x*→

β x*

10

β y*→

β y*

10€

L→100× L

→1.6 ×1036

(L =1.6 ×1034 )

€

N+N−nb →5.8 ×N+N−nb

εx →εx2

εy →εy2

β x*→

β x*

4

β y*→

β y*

2

€

z →σ z

€

z →σ z2

(hourglass)€

L→32× L

→5×1036

(L =1.6 ×1034 )

(crab waist)

(crab crossing)€

x,y = εx,yβ x,y

SuperBSuperB SuperKEKBSuperKEKB

with keeping N+N-nb

Beamcurrents

Attractive ! and are reachable !

Huge power consumption.

HOM/CSR

No evident for tiny and .

Issues for SuperB• Ultra-low emittance

– 10 times smaller than the present KEKB– Small machine errors and good control of beam orbits– How to handle Bunch-by-Bunch feedback system ?

• Ultra-low beta at IP– 10 times smaller than the present KEKB– Short focal length generates a large chromatic effect– In order to compensate this, strong sextupoles are needed.– Strong sextupoles reduce dynamic aperture....short lifetime.

• Crab waist scheme– Dynamic aperture (Touscheck lifetime/injection or BG)

• Dynamic aperture deteriorates to be about half if the crab waist scheme is applied to the KEKB lattice (results from simulations).

6

Issues for SuperB (cont’d)• Polarization of electron beam

– longitudinal polarization ~80 %.– Need polarized rf gun in linac injector.– Extremely strong spin rotators and/or geometrical

matching are needed. Are there any realistic solutions ?• Flavor factory

– Energy should go down for tau-charm physics.– Quality of magnetic field for bends, quads ?– XY-coupling is designed for a fixed energy in general.

XY-coupling should be zero at IP. Machine tuning becomes very difficult unless a detector solenoid changes proportonl to the energy.

7

SPARX 1st stage SuperB LINAC SPARX future

SuperB footprint on Tor Vergata siteSuperB footprint on Tor Vergata site

600 m

500 m

S. Tomassini’s talk, Monday

New tunnel !New linac injector !New infrastructures !

cooling systemAC power station

New buildings formany power supplies,klystrons!

Issues for SuperKEKB• Ultra-high currents

– a factor of 5 larger than the present KEKB– Strong synchrtron radiation– HOM heating– Can a bunch-by-bunch feedback system work ?– Electron-cloud in a positron ring ?

• Large beam-beam tune shift– a factor of 3 larger than the resent KEKB– Beam size in the vicinity of IP becomes large due to

dynamic emittance and dynamic beta.– Difficulties in the IR design. Physical aperture and

syncrtron radiation from IR magnets affect detector backgrounds.

9

Issues for SuperKEKB• Short bunch length

– half of the present KEKB– HOM heating– CSR instabilities

• Smaller beam pipe can suppress CSR. Down from 96 to 50.• 4 mm bunch length can suppress CSR. Luminosity deteriorates

by 16%.• Crab crossing scheme

– Development of crab cavities for the ultra-high current • LER: 9.4 A

– Is large beam-beam tune shift feasible ?• y ~ 0.2-0.3

• No polarization scheme 10

11

KEKB on KEK SiteKEKB on KEK Site

Mt. Tsukuba

Question ?

12

ILC Damping Ring + ILC FF = SuperB ?ILC Damping Ring + ILC FF = SuperB ?

ILC Damping Ring realizes small emittance,however NO IP and NO BEAM-BEAM !

ILC FF realizes small beta at IP,however colliding beams are SINGLE-PASS !

IR design for SuperB and SuperKEKB

13

HER 7 GeV HER 8 GeV

LER 3.5 GeVLER 4 GeV

?

LER 4 GeV

?

No detector solenoidNo compensation solenoid

Symmetric layoutalthough asymmetric collider !

SuperBSuperB SuperKEKBSuperKEKB

Bz

(T)

Bz

(T) 1.5 T

e- e-

e+B

eta

Bet

a

Bet

a

Bz

(T)

These are not latest version.

Crab waist study at DANE• 2 people from KEKB visited DANE and joined

commissioning in March 2008.

• We have a plan to send one or two people from KEKB for Autumn run to study the crab waist.

• We are very interested in a specific luminosity as a function of bunch current products between the crab sextupoles ON and OFF.– Both simulations and experimental data 14

SIDDHARTA

K monitor

Bhabha calorimeter

monitor

IP LAYOUT AND LUMINOSITY MONITORS

GEM Bhabha Monitor

SIDDHARTA K monitor

Bhabha calorimeter

monitor

IP LAYOUT AND LUMINOSITY MONITORS

CRAB SEXTUPOLES WORK !!

e- sextupoles off

e- sextupoles on

Transverse beam sizes at Synchrotron Light Monitors

LUMINOMETERS

Sextupoles can change beta, XY-coupling, dispersion, namely beam size at IP. Quantitative evaluation ?Sextupoles can change beta, XY-coupling, dispersion, namely beam size at IP. Quantitative evaluation ?

from P. Raimondi

DANE Machine Parameters

18

KLOEAchieved

SiddhartaDesign

Siddharta Achieved

Ib 13 13 12 mA

nb 110 110 95

x 340 200 250 nm

y/x 0.2-0.3 0.5 0.7 %

x* 170 20 24 cm

y* 1.7 0.65 0.96 cm

z 25 20 18 mm

x/2 12.5 25 25 mrad

x 0.04 0.008 0.009

y 0.04 0.055 0023

L 1.5 > 5 2.6 x1032 cm-2s-1

Specific luminosity is still lower than the target for the crab waist.Specific luminosity is still lower than the target for the crab waist.

Smaller betathan KLOE !

Eb = 500 MeVC ~ 100 m

Conclusions• INFN SuperB is very attractive.

– Smaller currents can get larger luminosity (above 1036).– a future generation for factory machine...Need more study.

• We keep the present design concept for the KEKB upgrade unless we obtain a good result of the crab waist at DANE.

• The KEKB upgrade is a natual extension of the present KEKB. We do not have to build the collider in a whole-new way.

• We have many resources and experiences for the high current scheme. We have studied the design of SuperKEKB since 2001 and already published LoI 2004 (corresponds to SuperB CDR).

19

20

5 years A. Suzuki

SuperKEKB fits in with KEK roadmap !

Backup Slides

21

Geometric luminosity gain

low vertical tune shift

Geometric luminosity gain

Very low horizontal tune shift

No parasitic collisions

short overlap region

Crab waist transformation(realized with two sextupoles@ in x and 1.5 in y from IP)

Geometric luminosity gain

Suppression of X-Y betatron and synchrobetatron resonances

Large Piwinski angle P=z / x

small y* (y* x /)

DANE

(KLOE run)

DANE Upgrade

Ibunch (mA) 13 13

Nbunch 110 110

y* (cm) 1.7 0.65

x* (cm) 170 20

y* (m) 7 2.6

x* (m) 700 200

z (mm) 25 20

Horizontal tune shift 0.04 0.008

Vertical tune shift 0.04 0.055

cross (mrad) (half) 12.5 25

Piwinski 0.45 2.5

L (cm-2s-1) 1.5x1032 >5x1032

DANE (KLOE run)

DANE Upgrade

BEAM PROFILES @IP AND NEW PARAMETERS

Old layout

New layout

splitters removed

new vacuum chambers @ IP

Bending angles changed, new independent power supplies

Crab sextupoles

XX

• Aluminum

•Window thickness 0.3 mm

IP

5.5cm

Time schedule is restricted.

Baseline is “HIGH current scheme”.

Alternative is low beta+low emittance+crab waist scheme

Luminosity upgradeLuminosity gain and upgrade items (preliminary)

Item Gain Purpose

beam pipe x 1.5high current, short bunch, electron cloud

IR(*x/y=20 cm/ 3mm) x 1.5 small beam size at IP

low emittance(12 nm) x → 0.5

x 1.3mitigate nonlinear effects with beam-beam

crab crossing x 2mitigate nonlinear effects with beam-beam

RF/infrastructure x 3 high current

DR/e+ source x 1.5low * injection, improve e+ injection

charge switch x ? electron cloud, lower e+ current

3 ye

ars

shut

dow

n

27

KEK

road

map

operation time : 240 days/year

Target forroadmap

Target forroadmap

Inte

grat

e lu

min

osity

(a

b-1)

Peak

lum

inos

ity (c

m-2

s-1)

Year

3 yearsshutdown

DampingRing

RF upgrade

KEKroadmap

Peak

cur

rent

(A)

KEK roadmap includes RF/DR (after 3 years shutdown)

Projected Luminosity (preliminary)

28

SuperKEKBIbunch (LER) = 1.87 mAIbunch (HER) = 0.82 mA

Specific luminosity with crab crossing

Beam-beamsimulation(strong-strong)

Specific Luminosity

Crab crossing•49-sp x*=80, 84cm x=18, 24 nm•3.5-sp x*=80cm•3.06-sp x*=80cm•3.06-sp x*=90cm

22 mrad crossing

y=-16.35x+26.54 Green Ratio=100%

Green line

y~0.093 (HER) (4/3)

31

x* = 0.8m

x* = 1.5m

= 1%

x* = 1.5m

= 1.3%

w/o crabx

* = 0.8m

Machine studyx

* = 1.5m