AcceleratorAccelerator

M. Biagini, LNF-INFNon behalf of the SuperB & DANE Teams3rd International Workshop on "B Factories and New Measurements"

Atami, Jan. 24th, 2008

&&DADANE crab waist experimentNE crab waist experiment

OutlineOutline

How to increase Luminosity? The new collision scheme SuperB beam-beam simulations SuperB parameters, layout, lattice DANE upgrade with new scheme DANE commissioning status Conclusions

SuperB Accelerator ContributorsSuperB Accelerator 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. Onhishi (KEK, Japan)

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

A. Wolski (Liverpool University, UK)

B. M. Venturini (LBNL, US)

S. Bettoni (CERN, Geneva)

A. Variola (LAL/Orsay, France)

E. Paoloni (Pisa University, Italy)

Increase beam currents

Decrease y* Decrease bunch

length

HOM in beam pipe overheating, instabilities,

power costs Detector backgrounds

increase Chromaticity increase

smaller dinamic aperture RF voltage increase

costs, instabilities

“Brute force” method

How to increase L ? How to increase L ?

But...

Hourglass effectHourglass effect

Bunch length

y*To squeeze the vertical beam

dimensions, and increase L, y at IP

must be decreased. This is efficient

only if at the same time the bunch

length is shortened to y value, or

particles in the head and tail of the

bunch will see a larger y.

Ultra-low emittance (ILC-DR like)

Very small at IP Large crossing angle “Crab Waist” scheme

Small collision area Lowerispossible

NO parasitic crossings NO synchro-betatron

resonances due to crossing angle

P. Raimondi’s: to focus more the beams at IP and have a “large” crossing angle large Piwinski angle

A new idea for L increase A new idea for L increase

Test at DANEnow !!!

Large crossing angle, small x-sizeLarge crossing angle, small x-size

Vertical waist has to be a function of x: Z = 0 for particles at –x (- x/2 at low current) Z = x/ for particles at + x (x/2 at low current)

(1) and (2) have same Luminosity, but (2) has

longer bunches and smaller x

1) Head-on,Short bunches

2) Large crossing angle, long bunches

Y

Overlap region

z

xz

x

y waist can be movedalong z with a

sextupoleon both sides of IP

at proper phase

“Crab Waist”

Large Piwinski angle:

= tg(z/x

Higher luminosity with same currents and bunch length: Beam instabilities are

less severe Manageable HOM

heating No coherent

synchrotron radiation of short bunches

No excessive power consumption

Lower beam-beam tune shifts

Relatively easier to make small x w.r.t.

short z

Parasitic collisions becomes negligible due to higher crossing angle and smaller x

... and ...... and ...

IP beam distributions for KEKB

IP beam distributions for SuperB

KEKB SuperB

I (A) 1.7 2.

y* (mm) 6 0.2

x* (mm) 300 39

y* (m) 3 0.039

x* (m) 80 6

z (mm) 6 5

L (cm-2s-1) 1.7x1034 1.x1036

Here is Luminosity gain

Beams are focused in the vertical plane 100 times more than in the present factories, thanks to:- small emittances- small beta functions - larger crossing angle

Tune shifts and longitudinal overlap are greatly

reduced

0

5 1036

1 1037

1,5 1037

2 1037

2,5 1037

0 2,5 1010 5 1010 7,5 1010 1 1011 1,25 1011 1,5 1011

Luminosity [cm-2 s-1]

N0,5

1

1,5

2

2,5

3

3,5

0 3 1010 6 1010 9 1010 1,2 1011 1,5 1011

N

Vertical Emittance Blow Up

Gaussian Fit

rms

0,95

1

1,05

1,1

1,15

0 3 1010 6 1010 9 1010 1,2 1011 1,5 1011

N

Horizontal Emiittance Blow Up

Gaussian Fitrms

0,96

0,98

1

1,02

1,04

1,06

0 3 1010 6 1010 9 1010 1,2 1011 1,5 1011

N

Longitudinal Emittance Blow Up

Gaussian Fit

rms

Luminosity and blow-up vs currentLuminosity and blow-up vs current

M. Zobov

Luminosity vs tunes scanLuminosity vs tunes scan

0.5 0.52 0.54 0.56 0.58 0.6 0.62 0.64

0.5

0.52

0.54

0.56

0.58

0.6

0.62

0.64

(horizontal axis - x from 0.5 to 0.65; vertical axis – y from 0.5 to 0.65)

• Individual contours differ by 10% in luminosity

• Design luminosity can be obtained over a wide tune area

P. Raimondi, D. Shatilov, M. Zobov

Transparency conditionTransparency condition

Due to the large crossing angle, new conditions are possible, different from asymmetric currents, for having equal tune shifts with asymmetric energies

LER and HER beams can have different emittances and * and equal currents

E

E

N

N

E

E

y

y

Present B-factories SuperB

E

E

y

y

LER beam: • sees a shorter overlap region, (4/7 of the HER one)

• has a smaller y*, easier to

achieve in the FF w.r.t. HER• has larger emittance: better for Touschek lifetime, and tolerance for LER instabilities

xx

xxyy

yyyy

E

E

E

E

E

E

E

E

,

e+e-

LER z

HER z

SuperB parameters (1)SuperB parameters (1)

Present parameter set based on ILCDR-like parameters Same DR emittances Same DR bunch length 1.5 times DR bunch charges Same ILC-IP betas

Crossing angle and “crab waist” to maximize luminosity and minimize blowup Presently under test at DANE

Use PEP-KEK DR damping time 19 ms No “emittance” wigglers used in Phase 1

SuperB parameters (2)SuperB parameters (2)

ILC/FFTB like Final Focus Design based on recycling all PEP-II hardware,

Bends, Quads and Sexts, and RF system Corresponds to a lot of money !

Maximize Luminosity keeping low wall power: Total power: 17 MW, lower than PEP-II

Simulations performed in many labs and with different codes: LNF,BINP,KEK,LAL,CERN

Circumference (m) 1800.

Energy (GeV) (LER/HER) 4/7

Current (A)/beam 2.

No. bunches 1342

No. part/bunches 5.5x1010

(rad) 2x24

x (nm-rad) (LER/HER) 2.8/1.6

y (pm-rad) (LER/HER) 7/4

y* (mm) (LER/HER) 0.22/0.39

x* (mm) (LER/HER) 35/20

y* (m) (LER/HER) 0.039

x* (m) (LER/HER) 10/6

z (mm) 5

Power (MW) 17

L (cm-2s-1) 1.x1036

SuperB Parameters (Phase 1)SuperB Parameters (Phase 1)

Transparencyconditions

Ring LayoutRing LayoutLength 20 m Total length ~1800 m

Length 280 m

HER

No polarization section here

Crossing angle to 2*25 mrad, L*=0.4 m Local chromaticity correction Horiz.beam separation at QD0: 2 cm, about 180 x

A possible solution with a septum QD0, to avoid the high background rate in the detector which would be produced by the over-bend off-energy particles if a dipolar component is present, is being studied.

In the novel design, based on SC “helical-type” windings, the windings generate pure quadrupole field as a superposition of the inner field of the surrounding coil and of the outer fringe field of the neighbor one (Bettoni, Paoloni). Overall thickness ~ 8mm, leaving about 60 x of beam stay-clear.

Final FocusFinal Focus

IP layoutIP layout

M.Sullivan

-0.3

-0.2

-0.1

0

0.1

0.2

0.3

-2.0 -1.5 -1.0 -0.5 0.0 0.5 1.0 1.5 2.0

x (cm)

By

(T)

S. Bettoni, E. Paoloni

Work in progress

Example of QD0 designExample of QD0 design

PolarizationPolarization

Polarization of one beam is included in SuperB Either energy beam could be the polarized one. The LER would be less expensive.

Long polarization times and short beam lifetimes indicate a need to inject polarized electrons in the vertical plane

There are several possible IP spin rotators Solenoids look better at present

Expected longitudinal polarization at the IP of about 87%(inj) x 97%(ring)=85%(effective)

J. Seeman, International Review Committee Meeting, LNF, Nov.07

DADANE upgrade with “crab waist”NE upgrade with “crab waist”

D. Alesini, M. E. Biagini, C. Biscari, R. Boni, M. Boscolo, F. Bossi, B. Buonomo, A. Clozza, G. Delle Monache, T. Demma, E. Di Pasquale, G. Di Pirro, A. Drago, A. Gallo, A. Ghigo, S.

Guiducci, C. Ligi, F. Marcellini, G. Mazzitelli, C. Milardi, F. Murtas, L. Pellegrino, M. Preger, L. Quintieri, P. Raimondi, R. Ricci, U. Rotundo, C. Sanelli, M. Serio, F. Sgamma, B. Spataro, A.

Stecchi, A. Stella, S. Tomassini, C. Vaccarezza, M. Zobov (INFN/LNF)

I. Koop, E. Levichev, P. Piminov, D. Shatilov, V. Smaluk (BINP)

S. Bettoni (CERN, Geneva)

K. Ohmi (KEK)

N. Arnaud, D. Breton, P. Roudeau, A. Stocchi, A. Variola, B. F. Viaud (LAL/Orsay)

M. Esposito (Rome1 University)

E. Paoloni (Pisa University)

P. Branchini (Roma3 University)

M. Schioppa (INFN Gruppo di Cosenza)

P. Valente (INFN-Roma)

DANE Upgrade Team

DANE performances

DADANE Upgrade ParametersNE Upgrade ParametersDANEFINUDA

DANE Upgrade

cross/2 (mrad) 12.5 25

x (mmxmrad) 0.34 0.20

x* (cm) 170 20

x* (mm) 0.76 0.20

Piwinski 0.36 2.5

y* (cm) 1.70 0.65

y* (m) 5.4 2.6

Coupling, % 0.5 0.5

Ibunch (mA) 13 13

Nbunch 110 110

z (mm) 22 20

L (cm-2s-1) x1032 1.6 10

Larger Piwinski angle

Lower vertical beta

Already achieved

DADANE test expected resultsNE test expected results The upgrade of DANE run the new collision scheme will allow for peak

luminosities of 1033 cm-2 s-1

The use of “crab waist” sextupoles will add a bonus for suppression of dangerous resonances

Brand new IRs layout and equipments have been designed, constructed and installed

This test will have the fundamental function of validating the simulation

(BBI code by K. Hirata)

Luminosity vs beam current

Crab On 0.6/ Crab Off

0.06 0.08 0.1 0.12 0.14 0.16 0.18 0.2

0.06

0.08

0.1

0.12

0.14

0.16

0.18

0.2

0.06 0.08 0.1 0.12 0.14 0.16 0.18 0.2

0.06

0.08

0.1

0.12

0.14

0.16

0.18

0.2

Luminosity vs tunes scanLuminosity vs tunes scan M. Zobov

Crab Waist Off

Crab Waist On

(K. Ohmi, BBSS Simulations)

Single Bunch Luminosity

Crab Waist On

damping = 30.000 turns damping = 110.000 turns

x110 bunches = 1033 cm-2 s-1

Strong-Strong SimulationsStrong-Strong Simulations

Hardware modificationsHardware modifications

Interaction Region 2 (no collisions)Interaction Region 2 (no collisions)

SIDDHARTA SetupSIDDHARTA Setup

SIDDHARTA

Kaon monitor

Bhabha monitor monitorLead shield

QF1

Commissioning status (1)Commissioning status (1)

Rings closed end November First beams beginning of December Some BPMs problems due to new RF frequency

solved Maximum currents up to now 700/400 mA (e-/e+) Found pm quads lower gradient (2%) than

expected rematched optics Coupling ~ 0.4/1.1% (e-/e+) Crab waist optics implemented, phase between

sextupoles OK

Commissioning status (2)Commissioning status (2) Measured -functions and dispersion in

agreement with model Collisions started at 200 on 200 mA (e-/e+), 60

bunches Measured vertical IP size: y = 8.1 m Tuning of all subsystems in progress SIDDHARTA Detector will be installed first week

of February

Beam currents in 24 h

New large Piwinski angle scheme in SuperB will allow for peak luminosity 1036 cm-2 s-1 well beyond the current state-of-the-art, without a significant increase in beam currents or shorter bunch lengths

Use of “crab waist” sextupoles will add a bonus for suppression of dangerous resonances

Expected luminosity increase due to “Crab Waist” is:

a) a factor of 3, at least, for the DANE upgrade

b) about 2 orders of magnitude for the SuperB project

(with respect to the existing B-Factories)

The principle is being tested at DANE

Conclusions (1)Conclusions (1)

There is an international interest and participation in SuperB A CDR is being reviewed by the International Review

Committee In case of positive answer a TDR will be ready by 2010 Next issues are: site, money, people

Conclusions (2)Conclusions (2)

Upgraded DANE is in commissioning phase

Collisions at low current started

Results are expected very soon