SuperB Design Progress
P. Raimondi
for the SuperB Team

Kek, March 20, 2007

Outline• Basic Concepts (March-Sept,2005)• Parameters and layout optimization based on aHigh-Disrupted regime (Nov, 2005)• Parameters and layout optimization for a
Minimal-Disrupted regime (Jan, 2005)• Layout for a Ring Collider with Linear Collider
Parameters (Mar, 2006)• Optimization of the SuperB design(Nov, 2007)• Status of the SuperB collaboration• Where when and how to build the SuperB• Conclusions

Basic concepts• SuperB factories based on extrapolationg
current machines require:• Higher currents• Smaller damping time (weak function ^1/3)• Shorter bunches• Higher power• KeK Proposal based on these concept
SuperB gets very expensive and hard tomanage, expecially all the problems related
to the high current => look for alternatives

Summary from Oide’s talk at2005 2nd Hawaii SuperBF Workshop•

Present design of SuperKEKB hits fundamental limits in thebeam-beam effect and the bunch length (HOM & CSR).

•

Higher current is the only way to increase the luminosity.

•Many technical and cost issues are expected with a new RFsystem.

•We need a completely different collider scheme.....

• Basic Idea comes from the ATF2-FF
experiment
In the proposed experiment it seems
possible to acheive spot sizes at the focal
point of about 2µm*20nm at very low
energy (1 GeV), out from the damping ring
• Rescaling at about 10GeV/CM we should get
sizes of about 1µm*10nm =>• Is it worth to explore the potential of aCollider based on a scheme similar to theLinear Collider one
Idea presented at the Hawaii workshop on
Super-B factory on March-2005 (P.Raimondi)

Scaling laws to optimize the IP parameters• Disruption:• Luminosity

N! zD"(! x! y )NL"(! x! y )2

Decrease σz + decrease N
Increase spotsize

Increase N
Decrease spotsize

Contraddicting
requests!

• Energy spread:N"E # 2(! x ! z )2Increase σz + decrease N
Increase spotsize

A lot of homework done in collaboration at
SLAC and at the LNF for a few months.
Explored the parameters phase in order tomaximize the luminosity per crossing
Laid down all the other possible advantages(e.g. less current through the detector,smaller beams, smaller beam pipe etc)
Leading to a workshop held on Nov,11-12
2005 in Frascati to investigate and optimize
the scheme and the feasibility of thedifferent subsystems

Horizontal Collision

Vertical collision

Effective horizontal size during collision about 10times smaller, vertical size 10 times larger
First attempt

Simulation by D.SchulteLinear Super B schemes with accelerationand energy recovery, to reduce power
2 GeV e+ injection
2GeVe+ DR

4 GeV eIP

5GeV e+ SC Linac

7GeV e+Overall rings lenght about 6Km, •Collision frequency about•
120Hz*10000bunch_trains=1.200MHz•
Bunch train stays in the rings•
for 8.3msec, then is extracted,compressed and focused. Afterthe collision is reinjected in its
ring

e- Gun4GeV e- SC Linac
e- Dump

Use SC linacs to recover energy
Use lower energy damping rings to
reduce synchrotron radiation
No electron damping ring
Make electrons fresh every cycle– Damping time means time toradiate all energy– Why not make a fresh beam if
storage time is greater than 1damping timePower budget with this schemes••••••4 x 7 GeV
10000 bunches at 1011 = 6A(e+)/12A(e-)
Damping ring RFfreq= 500 MHz at 0.6 m spacing
SC linac for 5 GeV e- with low emittance photo-gun
5.5GeV SC linac, frequency = 1300 MHz
Damping ring for 2 GeV positrons with wigglers– 3000 m damping ring at 3.7 msec damping– 3000 m damping ring at 4.6 msec damping time

•
•
•
•
•
•
•
•
•

120 Hz collisions for 8.3 msec cycle time
Assume two damping times between collisions sum 8.3 msec
Recycle energy for both beams in SC linac structures
2GeV ring: 10 MeV/turn, Pwall =100 MW
Accelerate 1011 particles to 5 GeV (e+) and also 4 GeV (e-)
Without energy recovery, beam generation power = 211 MW
Assume energy recovery is 99% efficient, needed power = 2 MW
Cyrogenic power (1W/MeV) Pwall = 5 kW*1000=5MW
Total power = 110 MW
J. Seeman study

Progress in design optimization after
the 1° SuperB workshop
Between December-2005 and March-2006 a lot ofstudies have been made in order to understand what
are the sources of the blow-ups in the collision andhow to minimize then.
Power requirements could be greatly reduced if
collision is less disruptive
Search for a trade off between luminosity delivered in
one collision and power spent for each collision
Search for the simplest and more economic solution

A lot of study done to find a solution that meets the“Small Disruption requirements”:
small σz
big σxsmall σy (for luminosity) and βy• Best luminosity always obtained with collision in
the ring, ILC-colliding scheme ruled out:
higher collision rep-rate
lower current
lower beam-blowup• Flat beams compressed colliding in the rings• Flat beams, uncompressed colliding in the rings, BBcompensation with Crab-Waist

Simplified layout in theSmall
Disruption
RegimeCollisions every TurnILC ring with ILC FF
ILC Compressor, 0.4GeV S-Band or 1GeV L-Band
Crossing angle optional

Decompressor

Decompressor

FF IP FF
Compressor

Compressor

Crossing angle concepts
Overlappingregion

Both cases have the same luminosity,(2) has longer bunch and smaller σx

Sx

Sz

With large crossing angle X and Z
quantities are swapped: Very important!!!

1) Standard
short bunchesOverlapping
regionSz2) Crossing angle

Sx

High luminosity requires:- short bunches- small vertical emittance- large horizontal size and emittance to mimimize
beam-beam
For a ring:- easy to achieve small horizontal emittance andhorizontal size
- Vertical emittance goes down with the horizontal- Hard to make short bunches
Crossing angle swaps X with Z, so the highluminosity requirements are naturally met:
Luminosity goes with 1/εx and is weakly dependentby σz

xβYe+e-2Sx/θθ2Sz*θ

z
2Sz2SxCrabbed waist removes bb betratron coupling
Introduced by the crossing angle
Vertical waist has to be a function of x:
Z=0 for particles at –σx (- σx/2θ at low current)
Z= σx/θ for particles at + σx (σx/2θ at low current)
Crabbed waist realized with a sextupole in phase with the IP in
X and at π/2 in Y

Horizontal Plane

Vertical Plane

Collisions with uncompressed beams
Crossing angle = 2*25mrad
Relative Emittance growth per collision about 1.5*10-3
εyout/εyin=1.0015

Simplified layout in theSmall Disruption RegimeCollisions every Turn
Uncompressed bunches
Crossing angle = 2*25 mrad
Crabbed Y-Waist

ILC ring &ILC FF

FF IP FF

During the last year we have optimized
design and parameters based on:
Large (piwinski) crossing angle and crabwaist concept
Small horizontal emittance, vertical beta andbeam size
Reuse of all the PeP hardware

Reoptimization of the ring parameters in 6months studies•

Relaxed damping time, now chosen like the PEP one: 10msec=>16msec•Relaxed y/x IP βs: 80µm/9mm => 300µm/20mm•Relaxed y/x IP σs: 12.6nm/2.67µm => 20nm/4µm•

Relaxed crossing angle: 2*25mrad => 2*17mrad•

Possible to increase bunch length: 6mm => 7mm•

Possible increase in L by further β’s squeeze•

Possible to operate with half of the bunches and twice the bunch charge(same current), with relaxed requirements on εy: 2pm => 8pm (1% coupling)•

Possible to operate with half of the bunches and twice the bunch charge(same current), with twice the emittances
Possible to have two interaction points•

Scan above Half Integers
0.64

In the first order in perturbation

0.62

nQx + mQy + kQs = integer
0.6

m should be even
0.58

(n + k) should be even

0.56

Qs = 0.02

0.54

0.52

Lmax = 1.21x1036 cm-2s-1

0.5
0.5

0.52

0.54

0.56

0.58

0.6

0.62

0.64

2Qx – 4Qs (first order)
2Qx – 2Qs (first order)
M.Zobov, D.Shatilov

2Qx – 1Qs (higher order)
4Qx – 2Qs (first order) ?

Luminosity Tune Scan
1 IP

Qy
0.2

0.2

0.18

0.18

0.16

0.16

0.14

0.14

0.12

0.12

0.1

0.1

0.08

0.08

0.06

0.06
0.06

0.08

0.1

0.12

0.14

2 IPs

Qy

0.160.18

Lmin = 3.95 x 1034 cm-2s-1
Lmax = 1.02 x 1036 cm-2s-1
M.Zobov, D.Shatilov

0.2Qx

0.06

0.08

0.1

0.12

0.14

0.16

0.18

Lmin = 3.37 x 1034 cm-2s-1
Lmax = 1.00 x 1036 cm-2s-1

0.2Qx

Double Phase Advance Scan
Δµy/2
1 π

Δµx, Δµy are phase advances
between IP1 and IP2
The total tune (0.155, 0.185)

0.8

0.60.5925

The best choice is symmetric0.42 x (Δµx/2π) = 0.155 + integer
2 x (Δµy/2π) = 0.185 + integer

0.2

0.0925
000.2

0.4

0.6

0.57750.8

1Δµx/2π

Sd

Sf
Sd

Sd

Sf

Sf

Sf

FFTB-stile
Final Focus

Sf

IP phase
sexts-I restoring“weak” sextupoles

Ring+FF BandwidthSuperB: sb70_ff_linepro12

Y. Ohnishi

IPSuperB Interaction Region
20

HER radiative bhabhas
10

B0H
B0L
QF1

B00H

QD0H

B00L

QD0

QD0

QF1

cm
00.5 1
1.52 3
QD0H 4
2.5 3.5-10

4.55

B0H

B0L-2

6 6.5

QF1

QF1-20-35.5-10m

123M.Sullivan
Nov. 13, 2006
SB_IT_ILC_G3_300

HER Ring Lattice• We have proven the feasibility of small emittance rings
using all the PEP-II magnets, modifying the ILC DRdesign• The rings have circumference flexibility• The FF design complies all the requirements in term ofhigh order aberrations correction, needs to be slightly
modified for LER to take care of energy asymmetry• All PEP-II magnets are used, dimensions and fields are inrange• RF requirements are met by the present PEP-II RFsystem• Now that the lattice is in its “final” state, is time to have alook seriously at the hardware needs (RF locations, spacefor diagnostics, vacuum pumps, etc...)Dipoles SummaryLmag (m)

0.45

5.4

20.75

PEP HER-

192

8-

PEP LER

192

-

--

SBF HER

-

160

2-

SBF LER

144

162

144

SBF Total

144

176

4144

Needed000

144

SuperB Magnets
Shopping list

•160 (144 in Arcs+16 inFF) “PEP-II HER” dipoles
are used in SuperB HER•16 dipoles are used in FF
for SuperB LER•144 “PEP-II LER” dipoles
are used in SuperB LER
 need to build 144 newones, 0.75 m long

We have excess of:• 48 bends 0.45 m long• 16 bends 5.4 m long
• 4 bends 2. m long

All and just the Pep RF systemfits the SuperB needs

Wall Plug Poweraround 30 MWattCDR readyPossible site in the Tor Vergata University
close to the Frascati Lab

M. Sullivan

Toward a cost estimate• Rings rebuild by reusing about 90% of
Pep (300Meuro), 90 Meuro• Ring tunnel and collider hall 40Meuro• Injector system 90Meuro• Convetional facilities 50Meuro• Total about270Meuro• Possible fall back on the existing factories• The crabbed waist seems to be beneficial
also for the current factories• Potential to simultaneously boost theperformances of the existing machinesand do SuperB R&D

Novosibirsk is designinga tau-charm factory based
On The Crab-Waist

Large piwinski angle andCrab Waist will be usedin the Dafne run next fallto try to improve the luminosity
by a factor > 3

QF1sQD0

L [10^33]

14200um,20mm200um,15mm100um,15mm

12M. Zobov

108

Present achieved currents
L=1.5e32642

I [mA]00102030

4050

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 possible
Beam-Beam limit is way above the reachable currents

Siddharta (Kloe) side

Cost estimate
Kilo-Euros
PM quads

400

IR1 vacuum chambers

40

IR2 vacuum chambers

30

Kickers pulsers

140+100

Kickers

60

Matching chambers for kickers

30

Vacuum pumps and components

60

New wigglers poles

200

External labor

90

Contingency+extras

150

Total1300

Time schedule• Final design ready• PM quads, the most critical component,delivered by June
• Bids for Vacuum chambers started at the end ofjanuary, orders by end of february, 3 months fordelivery• Orders for Kickers and ½ of the pulser underway, 3-4 months for delivery• Wiggler poles will not be done (budget cuts)

Conclusions• SuperB studies are already proving useful to theaccelerators and particle physics community• We have a preliminary “Conceptual Design Report”,
based on the reuse of all the Pep hardware, that might fit
in one of the existing facilities, or in a new (andavalaible) site near Frascati• The INFN will push any solution but particularly the lastone, expecially if the Dafne upgrade (SuperB based)
proves successful. A decision to ask for fundings to theItalian Government might happen already next year
(About 200MEuros, mostly for the injector and theconventional facilities)• We hope to gather in the enterprise as many labs andinstitutions as possible (See the CDR for the ones
already involved)