Toru Iijima Nagoya University · 2008-10-29 · Talk Outline KEKB & Belle Super KEKB & Belle – Physics target – KEKB upgrade – Belle upgrade Plan / New Collaboration Summary
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Toru IijimaToru IijimaNagoya University
October 29, 2008ICFA seminar @ SLAC
Talk Outline
KEKB & BelleSuper KEKB & Belle– Physics target– KEKB upgrade – Belle upgrade
Plan / New CollaborationSummary
Special Thanks to;J.Flanagan, K. Oide, Y. Sakai, Y. Ushiroda, M. Yamauchi
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KEKB & Belle
e+ source
Ares RF cavity
Belle detectorSCC RF(HER)
ARES(LER)
Peak luminosity1.71 x 1034 cm-2s-1 !
e- (8.0GeV) × e+ (3.5GeV)
⇒Υ(4S) →BB
⇒Lorentz boost: βγ = 0.425
Finite crossing angle
- 11mrad ×2
Operation since 1999.
3
4
KEKB PerformanceLuminosity Records;
L peak = 1.71x1034cm-2s-1 70% higher than the designL day = 1232pb-1/day double the designL int = 855 fb-1 as of Oct.28, 2008
The best day > 1.2 /fb1034
The power of Continuous Injection
KEKB/Belle:
709.9 fb-1
Υ(4S): 620.6 fb-
1 Υ(5S): 21.2 fb-1
Υ(3S): 2.9 fb-1
Off-peak: 58.9 fb-
1
Total:853 fb-1
Υ(4S): ~740 fb-1
Υ(5S): 23.6 fb-1
Υ(3S)/Υ(1S) 2.9 / 5.7fb-
Off-peak: ~85 fb-1
Lum / day
Achievement of the B Factories
Quantitative confirmation of the KM model
Af ~ 0Sf = 0.652±0.039±0.020
Violation of CP symmetry !
B0 J/ψKS
B0 J/ψKS
Belle, July 05
Belle, July 05
Discovery of CP violation in BB systemDiscovery of CP violation in BB system
Confirmation of Kobayashi-Maskawa modelConfirmation of Kobayashi-Maskawa model
WA, PDG08
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Achievement of the B Factories
Quantitative confirmation of the KM model
Af ~ 0Sf = 0.652±0.039±0.020
Violation of CP symmetry !
B0 J/ψKS
B0 J/ψKS
Belle, July 05
Belle, July 05
Discovery of CP violation in BB systemDiscovery of CP violation in BB system
Confirmation of Kobayashi-Maskawa modelConfirmation of Kobayashi-Maskawa model
WA, PDG08
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Press release from the Academy“As late as 2001, the two particle detectors BaBar at Stanford, USA and Belle at Tsukuba, Japan, both detected broken symmetries independently of each other. The results were exactly as Kobayashi and Maskawa had predicted almost three decades earlier. “
The next challenge is to find what KM cannot explain !
It requires >1010 B and τ pairs !
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Physics Reach at Super-KEKB/BelleBelle’06(~0.5ab-1)
5ab-1 50ab-1
ΔS(φK0) 0.22 0.073 0.029
ΔS(η’K0) 0.11 0.038 0.020
ΔS(KSKSKS) 0.33 0.105 0.037
ΔS(KSπ0γ) 0.32 0.10 0.03
Br(Xsγ) 13%
ACP(Xsγ) 0.058 0.01 0.005
C9 [AFB(K*ll)] --- 11% 4%
C10 [AFB(K*ll)] --- 13% 4%
Br(B+ → K+νν) <9Br(SM) 33ab-1 for 5σ discovery
Br(B+ →τν) 3.5σ 10% 3%
Br(B+ →μν) <2.4Br(SM) 4.3ab-1 for 5σ discovery
Br(B+ → Dτν) --- 7.9% 2.5%
Br(τ →μγ) <45 <30 <8
Br(τ →μη) <65 <20 <4
Br(τ → 3μ) <209 <10 <1
Δsin2φ1 0.026 0.016 0.012
ΔΦ2 (ρπ) 68°ー95° 3° 1°
ΔΦ3( Dalitz) 20° 7° 2.5°
ΔVub (incl.) 7.3% 6.6% 6.1%
0.01
0.1
0.3
0.03
Dev
iatio
n fro
m S
M
1 10 100Integ. luminosity (ab-1)
Presentexp. limits
5ab-1
50ab-1
CP asymmetry in B→KKK, φK and η’K
■ ● ★
(3σ discovery lim.)
Physics at Super B Factory (hep-ex/0406071) being updated.
X10-9
Search for H± in B→τν
50ab-1 assume5σ discovery
Integ. Lum.( ab-1 )Reach of B factories
Upgraded KEKB
Upper limits
CKM at 50ab-1
SuperSuper‐‐KEKB StrategyKEKB Strategy
L = γ±2ere
1+σ y*
σ x*
⎛
⎝ ⎜
⎞
⎠ ⎟ I±ξ± y
βy*RLRy
⎛
⎝ ⎜
⎞
⎠ ⎟
Stored current:1.7 / 1.4 A (e+/ e- KEKB) → 9.4 /4.1 A (SuperKEKB)
Beam-beam parameter:0.059 (KEKB) → >0.24 (SuperKEKB)
Vertical β at the IP:6.5 / 5.9 mm (KEKB) → 3.0 / 3.0 mm (SuperKEKB)
Lorentz factor
Classical electron radius Beam size ratioGeometrical reduction factors due to crossing angle and hour-glass effect
Luminosity:0.17 ×1035 cm-2s-1 (KEKB)5×1035 cm-2s-1 (SuperKEKB)
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Three factors that determine luminosityThree factors that determine luminosity
Crab cavities installed and undergoing testing in beam
The superconducting cavities will be upgraded to absorb more higher-order mode power up to 50 kW.
The beam pipes and all vacuum components will be replaced with higher-current design.
The state-of-art ARES copper cavities will be upgraded with higher energy storage ratio to support higher current.
SuperKEKB
e- 4.1 A
e+ 9.4 A
will reach 8 × 1035 cm-2s-1
L = γ±2ere
1+σ y*
σ x*
⎛
⎝ ⎜
⎞
⎠ ⎟ I±ξ±y
βy*RLRy
⎛
⎝ ⎜
⎞
⎠ ⎟
Dampiing ring
9
New IRβ*y = σz = 3 mm
Higher currentMore RFNew vacuum system
Crab crossing
+ Linac upgrade
10
Item Object Oku‐yen = 1.0 M$
Luminosity
New beam pipes
Enable high currentReduce e‐cloud
178(incl. BPM,
magnets, etc.)x1.5
New IR Small β* 31 x2
e+ Damping Ring
Allow injection with smallincrease e+ capture
40 incl. linac upgrade
if not, x0.75
More RF and cooling systems
High current 179(incl. facilities)
x3
Crab Cavities Higher beam‐beam param. 15 x2 ‐ x4
Items are interrelated.Tunnel already exists.Most of the components (magnets, klystrons, etc.)
will be re‐used.
High currents (9.4/4.1A) & short bunch (σz=3mm) lead to;– Intense SR power
Max. power density of 28kW/m (40W/mm2) even at half aperture.– High Photon density
~1x1019 photons/m/s in average.– Intense HOM power
For a loss factor of 1V/pC, loss power is ~200kW.
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Copper beam duct w/ ante‐chamberTiN coating on inner surface
• to decrease secondary electron yield (SEY); max.SEY~0.9
Clearing electrode• A possible measure even inside
of magnets
BeamSR
Pump
φ 90 mm
Adopt the same RF frequency as KEKB and use the existing RF system as much as possible, with improvements as necessary to meet the requirements for SuperKEKB.
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Construction cost is greatly reduced.
Technical uncertainties are relatively small.
Normal-conducting ARES cavity: LER + HERPassive stabilization with huge stored energy.T. Kageyama et al.
Superconducting cavity: HERS. Mitsunobu et al.
ARES Normal conducting cavity Superconducting cavity
Normal Conducting cavities (ARES):– Upgrade of ARES with higher energy storage ratio. (left)– High power rf input couplers.– SiC dummy load with higher power capability (right).
Superconducting cavities:– The expected power load to the HOM absorber is 50 kW/cavity at 4.1 A, (even) with a larger beam pipe of 220 mmφ.
– HOM damper upgrade may be needed.13
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SuperKEKB
KEKB
θ=17°θ=150°
EFC
QCSL QCSRESR-1ESR-2ESL-1 ESL-2
ESL ESRQCSL QCSR
Move final focus quad. closer to IP for lower beta functions at IP.Preserve current machine‐detector boundary.Rotate LER 8 mrad.Crossing angle: 22‐> 30 mrad
QCS and solenoid compensation magnets overlap in SuperKEKB.
Achieved KEKB design SuperKEKB unit
Beta (hor.) at IP βx* ~60 33 20 mm
Beta (ver.) at IP βy* ~6.5 10 3 mm
Bunch length σz ~7 5 3 mm
Crossing angle θx* ±11 ±11 ±15 mrad
Issues CausesPhysical aperture around IP Lower β at IPDynamic aperture Lower β at IPDetector background Higher beam currentHeating of IP components Higher beam current & shorter bunch length
Damping Ring
15
Pulse beam kicker for quick beam switching (50 Hz).
Start testing this Fall
Intensity Upgradese+: stronger focusing field in capture section after target.e-: increase bunch current from pre-injector
Energy Upgrade (Positrons)Replace S-band (2856 MHz) withC-band (5712 MHz) RF system to double field gradient in downstream section of linac.C-band linac:
completed a single section in the linac with 4 structures
Performance was satisfactory with beam.
Damping RingDamping RingPositron emittance needs to be damped, to pass reduced aperture of C‐Band section and to meet IR dynamic aperture restrictions.
– Electron DR may also be considered later to reduce injection backgrounds in physics detector, but for now only positron DR considered.
Damping ring located downstream of positron target, before C‐Band accelerating section.
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e+ Damping Ring
e+ productionJ-ARC
BTe- gun
Crab Crossing at KEKB Crab Crossing at KEKB Crab Crossing can boost the beam‐beam parameter > 0.15 .
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Crossing angle 22 mrad
Head-on (crab)
(Simulation:K. Ohmi)
22 mrad.22 mrad.crossingcrossing
crab crossingcrab crossing
Crab Cavity & Coaxial Crab Cavity & Coaxial Coupler in CryomoduleCoupler in CryomoduleK. Hosoyama et al.K. Hosoyama et al.
The squashed cell shape cavity studied by K. Akai in 1991 and 1992 under KEK-Cornell collaboration.
Test of Crab CrossingTest of Crab CrossingTwo crab cavities were installed in KEKB in January 2007.
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Beams have been indeed tilted !
one for each ringHER(8GeV e-) LER(3.5GeV e+)
LER HER
long
itudi
nal
horizontal
inside of the rings
outside of the rings
Observation with streak cameras (H. Ikeda et al, PAC07 FRPMN035)
Specific Luminosity With Crab CrossingSpecific Luminosity With Crab Crossing
A number of measurements indicate effective head-on collision.The vertical tune shift went from 0.055 to 0.088.The specific luminosity/bunch improved by more than just the geometrical gain, by about 15%.Need more time to achieve the goal (X2 specific luminosity).
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22 mrad crossing
3.06 bucket spacing
before crab, tune shift was 0.055
Simulation22 mrad
Simulationhead-on
Crab Crossing•49 sp. βx*=80, 84cm
the highest vertical beam-beam tune shift was about 0.088.
10 cm
BELLE
Super-Belle Strategy
10 cm
BELLE
- low p μ identification sμμ recon. eff.- hermeticity ν “reconstruction”
- radiation damage and occupancy- fake hits and pile-up noise in the EM
- higher rate trigger, DAQ and computing
IssuesHigher background ( ×20)
Higher event rate ( ×10)
Require special features
Possible solution:Replace inner layers of the vertex detectorwith a silicon striplet/pixel detector.Replace inner part of the central trackerwith a silicon strip detector.Better particle identification deviceReplace endcap calorimeter by pure CsI.Faster readout electronics and computingsystem.
Possible solution:Replace inner layers of the vertex detectorwith a silicon striplet/pixel detector.Replace inner part of the central trackerwith a silicon strip detector.Better particle identification deviceReplace endcap calorimeter by pure CsI.Faster readout electronics and computingsystem.
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Super-Belle (Baseline)
New Dead time free readout and high speed
computing systems
ECLWave sampling + pure
CsI crystal(endcap) PIDThreshold Aerogel + TOF→ TOP + Aerogel-RICH
SVD4-lyr DSSD → 6lyr DSSD(option: striplet / pixel )
CDCSuper small cellLonger lever arm
KL/μ detectionRPC → Scintillator
+SiPM(endcap)
Background EffectsEffective background with new hardwares
How Reduction factor Effective bkgSVD Shorter tp 50/800=1/16≈1/12.5 0 ~ 1CDC Smaller cell <2/3 4 ~ 13 (*)PID Brand new device Good enough 0 ~ 1B-ECL Waveform fitting 1/7 1 ~ 2E-ECL Pure CsI (shorter t) 1/200 0 ~ 1KLM Faster detector, finer segment Under control 0 ~ 1
(*) Software efforts needed for CDCBackground effects on trackingGain in reconstruction efficiency of B D*D*(D*→Dπs, D→K3π)
We know how to handle the background.
“sBelle Detector Study Report”posted as arXiv: 0810.4084
New
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KEK RoadmapKEK RoadmapKEK’s 5‐year roadmap.3‐year shutdown for KEKB upgrade
– 0.5‐1 year delay, KEKB will run in FY2009KEK management in close contact with MEXT.
– “Investigation money” requested in FY2008.
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HopePositive effects from the Nobel Prize …
Luminosity ProspectLuminosity Prospect
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3year shutdown for upgrade
10ab-1
(10x present)
Results from LHC(b)Situation of LC…
L~8x1035 cm-2s-1
50ab-1 by ~2020X50 present
New collaborationSuper-Belle will be a new international collab.– Two proto-collaboration meetings in Mar&Jul, 2008
• Participation of new people from Germany, India, U.S., Japan,… .– Kick-off of the new collaboration: Dec.10-12, 2008.
• Still many sessions will be open.
Near-term plan (preliminary)– Detector study report has been completed.– Detector proposals (by summer 2009).– The final detector design by Dec. 2009.
Detector proposals Internal review
TDR
Actions to invite new collaborators
Kick-off meeting(Dec 08)
20094 71 2 103 5 8 9 11 126
200810 11 12
20101 2 3
KEKB operation
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Super-Belle webpagehttp://superb.kek.jp/ML subscription is available.
SummarySummaryKEKB/Belle has been running successfully, and brought important scientific and technical achievements, together with PEP II/BaBar.Next generation e+e− B factory with L~1036 will be very useful to study the new sources of flavor mixing and CP violation.Super‐KEKB: the target luminosity is 8 x 1035cm‐2s‐1, based on existing or tested technologies (mostly), which enables us to accumulate 10ab‐1 by 2016, and 50ab‐1 by 2020. Super‐Belle: detector upgrade studies are in progress, and will be finalized in 2009. New proposals are still welcomed. New collaboration is being formed; the kick‐off meeting on Dec.10‐12 at KEK (many sessions will be open).
26We are trying to get ready soon. We are trying to get ready soon. Stay Tuned !Stay Tuned !
Backup
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Belle Detector
4 lyr DSSD
Belle CollaborationBelle CollaborationBINPChennaiChiba U.Hanyang U.U. of CincinnatiFu-Jen U.Giessen U.Gyeongsang Nat’l U.U. of HawaiiHiroshima Tech.HEPHY, ViennaIHEP, ProtvinoIHEP, BeijingINFN, TorinoITEPKanagawa U.KarlsruheKEKKorea U.
Krakow Inst. of Nucl. Phys.Kyoto U.Kyungpook National U.U. of LausanneJozef Stefan Inst.MPI, MunichU. of MelbourneNagoya U.Nara Women’s U.National Central U.National United U.National Taiwan U.Nihon Dental CollegeNiigata U.Nova Gorica U.Osaka U.Osaka City U.Panjab U.Peking U.Princeton U.
Illinois U. - RikenSaga U.USTCSeoul National U.Shinshu U.Sungkyunkwan U.U. of SydneyTata InstituteToho U.Tohoku U.Tohuku Gakuin U.U. of TokyoTokyo Inst. of Tech.Tokyo Metropolitan U.Tokyo U. of A and T.Toyama Nat’l CollegeU. of TsukubaVPIYonsei U.
About 360 collaborators from 59inst./Univ.from 14 regions.
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Other Highlights
SMBelle, 2005
D0-D0 mixing
AFB in B K*l+l−
X(3872)
Many new resonances
b dγ transition
and more…
0
50
100
150
200
250
300
350
400
0 0.25 0.5 0.75 1EECL (GeV)
Eve
nts
/ 0.0
5 G
eV
0
20
40
60
80
100
120
140
160
0
Eve
nts
/ 0.0
5 G
eV
0
20
40
60
80
100
120
140
160
0 0.25 0.5 0.75 1EECL (GeV)
Eve
nts
/ 0.0
5 G
eV
0
10
20
30
40
50
60
70
0
Eve
nts
/ 0.0
5 G
eV
Evidence for B τν
Z(4430)Signal
B D*τν
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What is next with flavour physics?
LHC will start soon to explore the TeV region, which is the scale of the electroweak symmetry breaking, and most probably related to the “New Physics” scale.– It is natural to assume that the NP
effects are seen in B/D/τ decays.– Flavour structure of new physics?– CP violation in new physics?– These studies will be useful to
identify mechanism of SUSY breaking, if NP=SUSY.
Otherwise…– Search for deviations from SM in
flavor physics will be one of the best ways to find new physics. Search for New Physics in precision meas.
In order for the flavor physics to be useful in the coming LHC era, the precision of variousflavor measurements must be significantly improved, both in terms of experimental reachand understanding of theoretical uncertainty.
In order for the flavor physics to be useful in the coming LHC era, the precision of variousflavor measurements must be significantly improved, both in terms of experimental reachand understanding of theoretical uncertainty.
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Present upperlimits
Measurementsat upgraded KEKB
( ab-1 )
Reach of presentB factories
Reach of upgradedKEKB
Dev
iatio
n fro
m S
M
Deviation from SMDeviation from SM
Relevant to baryogenesis?
Relevant to baryogenesis?
New source of CP violation
New source of CP violation
CP asymmetries of penguin dominated B decays
Searches for new sources of quark mixing and CP violation
32
Precise measurements of τ decays
LF violating τ decay?
Integ. Lum.( ab-1 )Reach of B factories
Upgraded KEKB
Upper limits
τ−>μγ
μ->eγ
τ−>eγ
T.Goto et al., 200733
Comparison with LHCb
e+e− is advantageous in… LHCb is advantageous in…
CPV in B→φKS, η’KS,…
CPV in B→KSπ0γ
B→Kνν, τν, D(*)τν
Inclusive b→sμμ, see
τ→μγ and other LFV
D0D0 mixing
CPV in B→J/ψKS
Time dependent measurements of BS
Bc and bottomed baryons
Most of B decays not including ν or γ
B(s,d)→μμ
These are complementary to each other !!
34
Lattice DesignNew IR(design,magnets,vacuum pipes…)Components for higher currents
– Vacuum components (pipes/bellows…)– Modification of the monitors (BPMs,SRMs…)– Longitudinal bunch‐by‐bunch FB system– More RF cavities and klystrons– Modifications of the RF systems for higher currents– Crab cavities for SuperKEKB
Some magnets/power supplies need to be newly fabricated.Damping ringLinac upgradeFacilities upgrade
35
R&D’s for all components in progress.Crab cavities are tested in beam.
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symbol LER HER unit
Beam Energy E 3.5 8.0 GeV
Beam current I 9.4 4.1 A
Circumference C 3016 m
Number of bunches nb 5018
Number of particles N/bunch 11.8 5.1 x1010
Emittance εx 9 nm
Emittance ratio εy/εx 0.5 %
Beta (hor.) at IP βx* 200 mm
Beta (ver.) at IP βy* 3 mm
Bunch length σz 3 mm
Crossing angle θx* 30 to 0 mrad
Beam‐Beam (hor.) ξx 0.36
Beam‐Beam (ver.) ξy 0.43
RF AC plug power PAC 73 MW
Luminosity L 8.0 x1035 cm‐2s‐1
Why the specific luminosity drops faster than Why the specific luminosity drops faster than expected ?expected ?
SpeculationsLifetime may be limited by the dynamic‐β and dynamic emittance caused by beam‐beam.To save the lifetime, two beams have been collided with horizontal offset by about 50 μm, which violates the perfect horizontal symmetric collision.The single beam vertical emittance may not be sufficiently smallElectron Cloud in the LER: Luminosity becomes better for longer bunch spacing.The SPOOABS nature in the optimum condition of the collision: Too many parameters.Synchrotron‐betatron resonance near the 1/2 integer tune... and more ..
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Lattice Design: the arc sectionLattice Design: the arc section
The beam-opticalparameters can be adjustedto SuperKEKB withoutchanging the latticein the arc section.
KEKB lattice:2.5π cell and non-interleaved chromaticity correction scheme.
→Wide tunability of horizontal emittance, momentum compactionfactor.
→Principle nonlinearities in sextupole pairs cancelled out to give large dynamic aperture
38
Comb-type RF shield
Features (compared to finger type):
Low beam impedanceHigh thermal strengthApplicable to complex apertureLittle flexibility (offset)
Effect of RF shielding wasdemonstrated in KEKB.Finger-type as an option
If more flexibility is required.39
Without cooling fan
Comb-type RF-shield
Temperature of bellows
Big impedance sources in the ringPlanning to use “stealth” type (Ver.6)
Low beam impedancePresent Ver.4 ~ 1V/pC (φ 90 mm) 200 kW power loss
Loss factor decreases to ~1/10 (φ 90 mm).Manageable by conventional HOM absorber
40
Loss factor
Bunch length [mm]
Loss
fact
or [V
/pC
] Ver.4
Ver.6
Ver.4
Ver.6
(1) 12 cured double pan-cake coils.(2) Curing process of 6 layer coils. This process is
necessary for improving the field quality in the magnet straight section (magnet body).
(1)
(2)
N. Ohuchi
41
Beam Background
1st layer
Rad-Bhabha mask around QCS magnetand IR chamber being designed
Results based on GEANT sims validated by Belle/KEKB experience.
Conservative & robust detector should handle up to 20 x more background 42
(GeV)LERE3 3.2 3.4 3.6 3.8 4
Ld
t∫
Rat
io o
f
0.8
0.9
1
1.1
1.2
1.3
January 25, 2008 BNM2008@Atami 43
sKEKB: Beam Energy Asymmetry
− J/ψK0 tCPV− φK0 tCPV− B τν BF
better
worse
• Toy MC results considering Δt resolution and geometrical acceptance.
• Geometrical acceptance is assumed to be same as the current Belle detector.
KEKB
ELER = 3.5 GeV looks good
43
Very Forward Detector
44
Challenges:Very high backgroundMagnetic field
F-CAL for ILC?
44
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