Transcript ppt

Super-B Factory Scenarios
John Seeman
Assistant Director
PPA Directorate
SLAC
SLUO Meeting
September 11, 2006
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Super-B Contributors (Accelerator):
LNF:
Pisa:
BINP:
KEKB:
SLAC:
Caltech:
Also:
Biagini, Raimondi, Zobov
Giorgi, Paoloni
Koop, Levichev, Shatilov
Ohmi
Novokhatski, Roodman, Seeman,
Seryi, Sullivan, Wienands
Albert
PEP-II and KEKB staff
Super-B Workshops
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Frascati: November 2005
Daresbury: April 2006
SLAC: June 2006
KEK: September 13-15, 2006
SLAC: October 19-24, 2006
Frascati: November 13-15, 2006
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Outline
• There are two present avenues of study for a
future very high luminosity B-Factory:
– Super KEKB (extension of present machines)
• Use existing KEK tunnel, magnets, RF system,
• New injector, vacuum system, crab cavities, IR
• High current and high AC power
– “Damping ring style” collider “Super-B” (new concept):
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New lattice similar to ILC damping ring
New IR similar to ILC final focus
Crab-waist for low vertical beta but long bunches
Present currents and low AC power
Reuse “PEP-II RF and magnets”
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K. Oide
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0.79 ?
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To be tested in 2007
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K. Ohmi Sept 2006
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Horizontal tune even closer to the half integer (0.503)
K. Oide
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K. Oide
July 2006
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Super-B Factory
ILC “like” rings & ILC “like” Final Focus
P. Raimondi
FF IP FF
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Super-B Factory Design
• Design still fresh and changing
• Started with ILC parameters but has evolved
toward smaller rings as new features were
added:
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Full lattices developed
IR developed with good beam-stay-clear
New IR included in lattice studies
4 GeV x 7 GeV
Dynamic apertures are good
Tune plane is good.
Fewer bunches are needed, so shorter rings than ILC
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Possible site: Tor Vergata near Frascati and Rome
• Near INFN Frascati
• Near future subway
• 3 km rings possible
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K. Oide
July 2006
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LER beam
2*q=30mrad
L*=35cm
QF1_LER
QD0a
70cm
Dq=28mrad
35cm
QD0b
Dq=9mrad
IP layout
35cm
35cm
40cm
QD0a and QD0b have
the same Ks
QD0a is shared, all the
35cm
other quads are on the
beams trajectories
Raimondi August 2006
QF1_HER
HER beam
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Horizontal Plane
Vertical Plane
Collisions with crossing angle = 2*25mrad
and long thin bunches with a small vertical beta.
Raimondi
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x
bY
e+
e-
2Sx/q
q
2Sz*q
z
2Sz
2Sx
Crabbed waist removes bb betratron coupling
Introduced by the crossing angle
Vertical waist has to be a function of x:
Z=0 for particles at –sx (- sx/2q at low current)
Z= sx/q for particles at + sx (sx/2q at low current)
Crabbed waist realized with a sextupole in phase with the IP
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X and at p/2 in Y
FFTB-style
Final Focus
IP phase
sextupoles
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HER cell
Extra 1.2m bends
LER cell
Use PEP-II quads
and dipoles
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HER ring lattice with FF (Option A: 2.7 km)
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August 2006
HER ring lattice with FF (Option B: 1.7 km)
September 2006
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Energy (GeV)
4
7
2762
1.4
2762
1.05
Lbend(m)
2.1
10.8
N. bends
96
96
Bbend (T)
0.439
0.144
2.3
4.1
4
4
ts (ms)
7.0
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7.0
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ex (nm)
0.79
0.71
0.25%
0.25%
sE
1.0x10-3
1.1x10-3
Momentum compaction
1.85x10-4
3.90x10-4
0.012
0.026
Vrf (MV)
5.5
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Npart (x1010)
3.31
1.89
Ibeam (A)
2.5
1.44
Tousheck lifetime (min)
95
1100
Pbeam(MW)
5.7
5.9
C (m)
Bw (T)
Uo (MeV/turn)
Wiggler sections
sz (mm)
Emittance ratio
ns
Frf (MHz)
476
Nbunches
4167
Gap
5%
Pwall (MW) (50% eff) 2 rings
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Ring
Parameters
IP Parameters
bx
20mm
sx
4mm
sxp
200mrad
by
200mm
sy
20nm
syp
100mrad
sz
7mm
2*q
30mrad
August 2006
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Luminosity vs current
Luminosity [cm-2 s-1]
2,5 10 37
2 1037
Nominal
1,5 10 37
1 1037
5 1036
N
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0
2,5 10
10
5 10
10
7,5 10
10
1 10
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1,25 10
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1,5 10
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Zobov and Shatilov
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Beam size blowups vs current
Vertical Emittance Blow Up
3,5
Gaussian Fit
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rms
2,5
2
1,5
1
N
0,5
0
3 10
10
6 10
10
9 10
10
1,2 10
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1,5 10
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Zobov and Shatilov
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Luminosity Tune Scan
(0.8/q, sz = 7 mm; 3x1010 particles)
Lmax = 2.2x1036 cm-2 s-1
New Qx=0.57 Qy=0.60
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Luminosity and size blowups vs 2*q
New 2*q =30mrad, by=133mm
Larger crossing angle
Ay
Ax
Ax = (0.0:20sx) Ay = (0.0:40sy)
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Ring dynamic aperture with FFTB-FF
40sx
dp/p=0
20sy
20sx
dp/p=-0.5%
12sy
20sx
dp/p=0.5%
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12sy
Recent Super-B Parameters Optimization
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Relaxed damping time => 17msec
Relaxed y/x IP bs => 200mm/20mm
Relaxed y/x IP ss => 20nm/4mm
Relaxed crossing angle => 2*15mrad
Relaxed bunch length => 7mm
• L dependence quadratic with current up to 1037
• L of 2 x 1036 is “possible” for 25 to 30 MW.
• PEP-II magnets and 476 MHz RF system reused.
• Wiggler sections added to shorten damping time.
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Conclusions
• A very high luminosity B-Factory seems to
have several possible technical avenues.
• Recent studies show good progress for an
“ILC like” ring and FF solution but of
shorter length.
• The AC power is similar to present BFactories.
• The study group aim is to have a
“Technical Paper” written by the end 2006.
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