BINP Tau-Charm Project
description
Transcript of BINP Tau-Charm Project
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BINP Tau-Charm Project
3 February 2010, KEK, Tsukuba
E.Levichev
For the BINP C-Tau team
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Outline
1. Introduction of Crab Waist collision approach2. Scientific program and specifications3. Optics4. FF and QD05. Polarization insertions6. Energy calibration
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Crabbed waist is realized with a sextupole inphase with the I P in X and at / 2 in Y
2z
2x
z
x
2x/
2z*
e-e+Y
1. Large Piwinski’s angle = tg(z/x
2. Vertical beta comparable with overlap area y x/
3. Crab waist transformation y = xy’/(2)
Crab Waist in 3 Steps
1. P.Raimondi, 2° SuperB Workshop, March 2006
2. P.Raimondi, D.Shatilov, M.Zobov, physics/0702033
M.Zobov, Tau08, Novosibirsk
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x
y 2
x
y 2
Crabbed Waist Scheme
x
x
yy
K
*
*
1
2
1
Sextupole (Anti)sextupole
20 2
1yxpHH
Sextupole strength Equivalent Hamiltonian
IPyx , yx ,** ,
yx
*
2* /
yyy
xs
M.Zobov, Tau08, Novosibirsk
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Collisions with and without Crab Sextupoles
1. Bigger blowup
2. Sharp lifetime reduction for bunch currents > 8 -10 mA
February
2009
Courtesy G. Mazzitelli
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Frequency Map Analysis for CW
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Scientific case for the BINP C-tau project
► D-Dbar mixing► CP violation searches in charm decays► Rare and forbidden charm decays► Standard Model tests in leptons decays► Searches for lepton flavor violation →► CP/T violation searches in leptons decays► Production of the polarized anti-nucleons E = 1 GeV (may be with reduced luminosity)
Requirements: L > 1034 cm-2 s-1, longitudinal polarization, beam energy range from 1 GeV to 2.5 GeV
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Specifications
► Variable energy Ecm= 2 – 5 GeV
► Luminosity L = 1÷2×1035 cm-2s-1
► Electrons are polarized longitudinally at IP
► No energy asymmetry
► No beam monochromatization
► Energy calibration with medium accuracy
is sufficient (Compton backscattering)
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Facility key features and principles
► Two rings with a single interaction point► Crab waist collision► SC wigglers to keep the same damping and emittance in the whole energy range (optimal luminosity)► Polarized e- injector and spin control to get the longitudinally polarized electron beam at IP► Wide re-using of the existing structures and facilities tosave the cost
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Layout
Injection facility exists
Tunnel for the linac and the technical straight section of the factory is ready
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Main ring
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Main ring: tunnelReady-built tunnel FF region
Technical reg. (RF and injection)
Damping wiggler sections
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Main accelerator parameters
6 m of the SC wigglers with 20-cm-period are used to control the beam parameters at different energies
Energy 1.0 GeV 1.5 GeV 2.0 GeV 2.5 GeV
Circumference 783 m
Emittance hor/ver 10 nm/0.05 nm @ 0.5% coupling
Damping time hor/ver/long 30/30/15 ms
Bunch length 20 mm 13 mm 10 mm 10 mm
Energy spread 10.5·10-4 10.4·10-4 8.8·10-4 7.6·10-4
Energy loss/turn 174 keV 261 keV 349 keV 430 keV
Momentum compaction 1.00·10-3 1.06·10-3 1.06·10-3 1.06·10-3
Synchrotron tune 0.013 0.014 0.012 0.010
Wiggler field 5.4 T 4.0 T 2.8 T 0
RF frequency 500 MHz
Harmonic number 1260
Particles/bunch 7·1010
Number of bunches 294
Bunch current 4.3 mA
Total beam current 1.3 A
Beam-beam parameter 0.15 0.15 0.15 0.12
Luminosity 0.55·1035 0.81·1035 1.08·1035 1.08·1035
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Main ring: arc cellFODO but close to the theoretical minimum emittance
x, y
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Main ring: injection section
x, y
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IR optics
L1/2 = 75 m
x, y
IP
FF telescope
Y Section of chroms correction
X Section of chroms correction
Crab Sext
End of the telescope
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Luminosity D.Shatilov
0.5 0.55 0.6 0.65 0.7 0.75
0.5
0.55
0.6
0.65
0.7
0.75
0.5 0.55 0.6 0.65 0.7 0.75
0.5
0.55
0.6
0.65
0.7
0.75
Crab ON: ξy=0.13
Lbeam=2.76·1032 @ Np=7·1010
Lmax=1.05·1035 @ Nb=380
Crab OFF: ξy=0.06
Lbeam=4.94·1031 @ Np=3·1010
Lmax=0.44·1035 @ Nb=890
y=750 um, Θ=50, mrad, σz=1cm, x=10 nm·rad, 0.5% coupling
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Polarization scheme
IP
snake1
snake2 snake3
dampingwiggler1
dampingwiggler2
Polarization scheme with 3 snakes (arc=1200
+2 damping wigglers in the arc’s middle )
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Polarization vs energy
1 1.2 1.4 1.6 1.8 2 2.2 2.4 2.60
0.2
0.4
0.6
0.8
1
Beam Energy, GeV
Po
lari
zati
on
Deg
ree
5 snakes
1 snake
3 snakes
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QD0
SC iron yoke twin aperture magnet Excitation current 1150 ASingle aperture 2 cmGradient 150 T/m
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Damping wigglers
Field amplitude at 1.0 GeV 5.4 T
Period length 0.2 m
Total length 8 m
Damping integral i2 at 1.0 GeV 12.4 m-1
Excitation integral i5 at 1.0 GeV 0.08 m-1
The damping wigglers keep the damping time x =30 ms and thehorizontal emittance (εx=10 nm) in the energy range 1.0 – 2.5 GeV
Wiggler field amplitude vs energy
Wiggler with similar parameters produced by BINP
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Energy calibration
Compton backscattering Ecalibration (~10-410-5)
Spectrum edge 5105 E
E
Na24 (1)=1368.625 keV Na24 (2)=2754.008 keV
Na24 (1+2)=4122.633 keV
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Injection facility
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Injection facility upgrade
• Today:• 21010 e-/pulse (1.5% conversion) 3 108
e+/pulse 50 Hz = 1.51010 e+/s
• Upgrade:• e- current increase ( 3)• Better focusing in positron linac ( 1.5)• Debuncher usage ( 2)• = 1.351011 e+/s
• Reserve: electron energy can be increased by 100 MeV ( 1.3)
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Summary
► Crab Waist collision seems a very promising idea to enhance a circular colliders luminosity beyond the present value by factor of 10-100 without current increase.
► CW approach was successfully proved experimentally at DAFNE in the end of 2008
► Novosibirsk SuperCT project is under way. The key issues like IR design, DA optimization, polarization scheme, QD0 design, etc. seem solved successfully
► In 2010 we hope to finish a CDR and in parallel apply for funding to Russian Government.