Dafne Upgrade with large Piwinsky angle and crab waist

P. Raimondi

SLAC-Mac Oct.2006

Outline

• Dafne luminosity History

• Goals for the Finuda run

• Goals for the Siddarta run

• Mid-Long term plans

Luminosity history

DANE DELIVERED L IN YEAR 2004-5 for

KLOE

109-111 bunchesI-

peak =2.05 A I+

peak = 1.39 ALpeak = 1.53e32 cm-2s-1

Lday peak = 9.9 pb-1

Lmonth > 215 pb-1

L2004-5 > 2200 pb-1

2006-7 goals

LNF September 2006

• Finuda Run: Goal 1ft-1 by April 30, 2007

- Start Oct-02 with cold check-outs

- 1 month commissioning

- 6 months data taking• Siddartha Run: Goal 1ft-1 by Dec 31, 2007

- Install the new IR with cross-angle/crab-waist and Siddartha detector (2-3 months)

- start July-1st or Sept 1st

- 1 month commissioning

- 3 months data taking• Dafne Goal: 1033 By Dec 31, 2007

Finuda Run• Started on Oct-02• Reestablished collisions, stored >700mAmps e+/e-• Vacuum conditioning ‘til Oct-31• Better coupling correction wrt Kloe (just 2 rotating

quads instead of 4): 10%• Better e-ring impedance 20% (from shorter bunch

and vertical emittance blowup)• Better feedbacks >10% (more current and more

stable beams)• Reduced wiggler field (-10%)• Reduced run duration• 1.5*10^32 by the end of the run, 0.2ft-1/month duable

Siddarta Luminosity• New IR needed for Siddarta around mid-2007

Very straightforward its design to overcome some of the present limitations and test the large crossing angle scheme

No more parasitic crossing

Very small vertical beta function

Large Piwinsky angle

Crab waist• Fast kickers installed Better injection efficiency: 50%=>100%

No background=> topping up

Higher currents => more luminosity (10%)• Wigglers pole modified to improve acceptance

Longer lifetimes

Less backgroung

Higher integrated luminosity (10%)• Ti Coating in the e+ wigglers chambers

Decreased e-cloud => Higher e+ current, more luminosity (20%)

High luminosity requires: - short bunches - small vertical emittance - large horizontal size and emittance to mimimize beam-beamFor a ring:- easy to achieve small horizontal emittance and

horizontal size- Hard to make short bunchesCrossing angle swaps X with Z, so the high

luminosity requirements are naturally met

Luminosity goes with 1/x and is weakly dependent by z

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) Crabbed waist realized with a sextupole in phase with the IP in

X and at /2 in Y

2Sz

2Sx

z

x

2Sx/

2Sz*

e-e+Y

Crabbed waist removes bb betratron couplingIntroduced by the crossing angle

SuperB parametersCollisions with uncompressed beamsCrossing angle = 2*25mradNegligible Emittance growth

Horizontal Plane Vertical Plane

Luminosity considerationsIneffectiveness of collisions with large crossing angle is illusive!!!Loss due to short collision zone (say l=σz/40) is fully compensated by denser target beam (due to much smaller vertical beam size!).

cross2 2 cross x

z

lN N l 2 /

Number of particles in collision zone:

1 2 0

x y

N N fL

4

e 2 y

1yy x y

r N

2 ( )

1y 1 0 y 1y34 36 2 1

e y x y

N f E(GeV) I(A)L 1 2.167 10 1.2 10 cm s

2r (cm)

No dependence on crossing angle! Universal expression: valid for both - head-on and crossing angle collisions!

I. Koop, Novosibirsk

Tune shiftsRaimondi-Shatilov-Zobov formulae:(Beam Dynamics Newsletter, 37, August 2005)

2 2 2x z xtan ( / 2)

e xx

2 2 2 2 2 2z x z x y

yey

2 2 2y z x y

r N

2 tan ( / 2) tan ( / 2)

r N

2 tan ( / 2)

Super-B:

e xx 2 2

z

yey

y z

2r N0.002

r N0.072

2 2 2z x xtan ( / 2) 100 m 2.67 m

2 2 2z x

y

tan ( / 2)8000!!!

One dimensional case for βy >>σx/θ. For βy <σx/θ also, but with crabbed waist! I. Koop, Novosibirsk

“Crabbed” waist optics

1x x

x x x x1 1 11x x x xx x

y y y1 1 1y y y y

y y y y y

u 0 1 0u 0T T T T

F u 2u F 1F u

u F 0 F 1 0T T T T

F 0 F u 2u F 1

IP

Δμx=πΔμy=π/2

Δμx=πΔμy=π/2

x,yT x,yT+g -g

Appropriate transformations from first sextupole to IP and from IP to anti-sextupole:

Sextupole lens Anti-sextupole lens

I. Koop, Novosibirsk

Normalised Luminosity vs x and y tunes

Without Crab Focus With Crab Focus

M. Zobov

Vertical Size Blow Up (rms) vs x and y tunes

Beam size and tails vs Crab-waist

Simulations with beam-beam code LIFETRAC Beam parameters for DAFNE2.

An effective “crabbed” waist map at IP:0 0

0

Vy y xy

y y

Optimum is shifted from the “theoretical” value V=1 to V=0.8,since it scales like z/sqrt((z2+x

2)D.N. Shatilov, Novosibirsk

Synchrotron modulation of ξy (Qualitative picture)

ξy(z-z0)

Relative displacementfrom a bunch center

z-z0

Head-on collision.Flat beams. Tune shiftincreases for halo particles.

Head-on collision.Round beams. ξy=const.

Crossing angle collision.Tune shiftdecreases for halo particles.

Conclusion: one can expect improvement for lifetime of halo-particles!

I. Koop, Novosibirsk

0

2

4

6

8

10

12

14

0 10 20 30 40 50

200um,20mm200um,15mm100um,15mm

I [mA]

L [10^33]

With the present achieved beam parameters (currents, emittances, bunchlenghts etc) a luminosity inexcess of 1033 is predicted.With 2Amps/2Amps more than 2*1033 is possibleBeam-Beam limit is way above the reachable currents

M. Zobov

Present achieved currentsL=1.5e32

0

0,2

0,4

0,6

0,8

1

0 5 104 1 105 1,5 105 2 105 2,5 105

x^(-0.37)

x^(-0.48)

x^(-0.56)

x^(-0.50)

y0/y

turns

(0.057,0.097,-0.01)(0.057,0.097,+0.01)

(0.11,0.19,-0.01)(0.11,0.19,+0.01)

0,5

1

1,5

2

2,5

3

3,5

5 104 1 105 1,5 105 2 105

(0.057,0.097,-0.01)(0.057,0.097,+0.01)(0.11,0.19,-0.01)(0.11,0.19,+0.01)

turns

L, 10^33

Very weak luminosity dependence from damping time given the very small bb-blowup

Wigglers off

Dafne Wigglers

SC WigglersWigglers offSC Wigglers

Dafne Wigglers

M. Zobov

IR Layout• No splitters (on both sides)• Common beam pipe in QD0• Separated beam pipes since QF1• No dispersion in sextupoles due to splitters• Needs new extremely simplified vacuum pipe

(round everywhere, apart the y-one)• Dipole fields need to be ajusted (Blong lower,

Bshort higher) use splitters power supplies • Doublets will be PM• All the other elements (quads, sexts etc) are in

place, need just to be moved nearby

IR layout

New beam line

IP

QD0sQF1s

M.Biagini

View of the modified IR1 regionSimilar modifications will be made in the IR2, without the low-beta insertionIn addition in IR2 the two lines will be Vertically Separate

Siddarta

QD0Qf1s

Permanent SmCo quads already ordered (about 380K$ for 6 quads)All other IR magnets and power supplies reusedMost of the Vacuum Pipes and pumps reusedNew Vacuum pipes and pumps around 50K$

Dafne parameters for the Siddarta run

Np=2.65*10^10 I=13mAmp*110bunches

Emix=200nm Emiy=1nmCoupling= 0.5% sigx=200um betx=0.2msigy=2.4um bety=6.0mmsigz=20mm crossing_angle=2*25mrad

L(110bunches,1.43A)=10^33

y=y+0.8/*x*y’ crabbed waist shift

Optical functions and dynamic apertures

> 20 sigma_x

> 12 sigma_y full coupled

IR optics

x=0.2m y=6.0mmNew betas

x=1.4m y=18.0mmOld betas

M.Biagini

Dafne 2008 and beyond• If 10^33 is achieved (or some above 5*10^32) KLOE

will start a new run with an upgraded detector.• the only significant (in money) modifications on

Dafne could be:

- Transfer lines mods to allow trickle injection

- High Energy mods for NNbar experiment:

New Dipoles

Possibly X-Band Linac in the transfer lines to allow on energy injection

• If the luminosity does not seems satisfactory, the only other possibility left (at the present) is the new machine DANAE, already at an advanced project state.

Dafne Goals Conclusions• A new IR for Siddarta compatible with large-crossing angle

option seems feasible• Same IR can fit in KLOE(1 or 2)• Predicted large luminosity boost based exclusively on pure

“back of the envelope” geometric considerations, fully supported by extensive simulations

• 10 times more luminosity for a given current leads to a 10 times better luminosity/background ratio. Additional gain comes from the increased (about a factor 1.2) beam stay clear in the IR

• Possible to do top-of-the-line Accelerator Physics and R&D for future factories (e.g: SuperB)

• Simply rematching the IP betas, it will be possible to run like with KLOE 2004-5, with even larger beam stay clear across the doublet:

x: 0.2m => 1.4m y: 6.0mm => 18mm