status and perspectives of high luminosity flavour factories
DESCRIPTION
Status and Perspectives of High Luminosity Flavour Factories. M. E. Biagini, INFN/LNF EPS-HEP, Stockholm July 20 th 2013. Flavour Factories. Past: PEP - II @ SLAC, USA KEKB @ KEK, Japan Present: DA F NE @ INFN-LNF, Italy Vepp2000 @ BINP, Russia BEPCII @ IHEP, China Future : - PowerPoint PPT PresentationTRANSCRIPT
Status and Perspectives of High Luminosity Flavour Factories
Status and Perspectives of High Luminosity Flavour Factories
M. E. Biagini, INFN/LNF
EPS-HEP, Stockholm July 20th 2013
Flavour Factories
Past:
PEP-II @ SLAC, USA
KEKB @ KEK, Japan
Present:
DAFNE @ INFN-LNF, Italy
Vepp2000 @ BINP, Russia
BEPCII @ IHEP, China
Future:
SuperKEKB @ KEK
Proposals:
Tau-Charm @ BINP, INFN, IHEP, TAC (Turkey)
Super TC
Linear
Circular Xbeam
Super BF
e+e- colliders Luminosity vs Energy
The past
PEP-II B-Factory 1999-2008
KEKB B-Factory 1999-2010
Integrated Luminosity
KEKB tried crab cavities
Crab cavities installed in Feb. 2007 at KEKB and worked very well until the end of the KEKB operation
Highest luminosity with the crab cavities was about 23% higher than that before crab (prediction by bb simulation: ~100% increase)
Tuning with skew-sextupole magnets was effective to increase the luminosity with the crab cavity (~15% gain)
Found that skew-sextupoles are also effective to increase the luminosity when the crab cavities were switched off
Recipes for success
Efficient injection system Trickle injection
Tuning knobs beam control
Strenuous instabilities fight e-cloud mitigation, bunch-by-bunch feedbacks
Higher currents than design see a)
New ideas (crab cavities, skew sextupoles)
Stable RF system
Powerful diagnostics see b)
Skilled and expert staff
Standard Collision Scheme Limitations
1. Hourglass effect limits minimum IP b: by* sz
2. Bunch length reduction not advisable
bunch lengthening, microwave instability, CSR
3. Further multibunch current increase would result in
coupled bunch instabilities, HOM heating, higher wall-plug power
4. Higher emittances conflict with
beam stay-clear and dynamics aperture limitations
5. Tune shifts saturate, beam lifetime drops due to
beam-beam interactions
Less than 10 years ago the brute force (increasing currents) was the only approach to higher luminosity
P. Raimondi (LNF) studied a new collision scheme with larger crossing angle and lower IP beam sizes (Large Piwinski Angle) PLUS a couple of sextupoles to twist the IP waist and cure x-y and synchro-betatron resonances raising from the angle (Crab Waist). Test at DAFNE
Adopted by all Factory projects after 2008
Changing the approach
Oide, Progress of Theoretical Physics, Vol. 122, No. 1, July 2009
Large Piwinskis angle
F = tg(q/2)sz/sx
2. Vertical beta comparable
with overlap area
by 2sx/q
3. Crab waist transformation
y = xy/q
Crab Waist Advantages
Luminosity gain with N
Very low horizontal tune shift
Vertical tune shift decreases with oscillation amplitude
Geometric luminosity gain
Lower vertical tune shift
Suppression of vertical synchro-betatron resonances
Geometric luminosity gain
Suppression of X-Y betatron and synchro-betatron resonances
....and besides
No need to increase excessively beam current and to decrease the bunch length:
Beam instabilities are less severe
Manageable HOM heating
No coherent synchrotron radiation of short bunches
No excessive power consumption
Problem of parasitic collisions automatically solved due to higher crossing angle and smaller horizontal beam size
Less hourglass by* can be decreased
Crab sextupoles effect
Crab sextupoles are strong and introduce large non-linearity, optics between them has to be linear as much as possible
Dynamic Aperture is greatly reduced. Solutions:
Design IP doublet so to compensate the kynematic (octupole) and fringing field effects
Locally compensate the chromaticity (Y and X separately)
Add octupoles and additional sextupoles to compensate for the aberrations induced by the off-phase sextupoles
Adjust b and phase advance between crab sextupoles
Done for SuperB and Italian Tau/Charm: effect is reduced (not cancelled)
Design & operation challenges
Ultra low emittances (H, V) Coupling compensation
Interaction Region and Final Focus design (Low b*, IP quadrupoles)
Dynamic aperture (with fringing fields in IP quads and crab sextupoles)
Tolerances to machine errors and vibrations Low Emittance Tuning
Impedance budget
Lifetimes (bb bremsstrahlung, Touschek) trickle charge injection
High backgrounds detector protection
High beam currents injection system
Extreme vacuum with high currents
Short bunch distance kickers, feedbacks
Instabilities control (collective effects, b-by-b feedbacks)
Adequate diagnostics (SLM, BPM, BLM, b-by-b luminosity monitor)
On-line tuning knobs orbit, IP waist, dispersion, coupling, IP b, tunes, IP angles
.
Synergies
Most of the above topics (except for high beam currents and beam-beam issues) apply to modern design of 4th generation Synchrotron Light Sources
Low emittance tuning techniques (LOCO, LET, ) successfully applied
Record emittances measured at Diamond, SLS, ASLS (ey < 2 pm)
Dynamic Aperture optimization techniques (MOGA, FMA, ) give larger momentum and transverse acceptances
The two communities actively collaborate (see for example 3rd LOWeRING Workshop at Oxford, EuCARD2)
http://www.physics.ox.ac.uk/lowemittance13/index.asp
The present
DAFNE @ INFN-Frascati
First F-Factory with Large Piwinski Angle and Crab Waist collision scheme (adapted to previous IR design)
3xLuminosity boost with non magnetic detector SIDDHARTA
Proven effectiveness of crab sextupoles (very good agreement with numerical predictions and simulations)
New Interaction Region for KLOE2 magnetic detector
Limited in beam currents (e-cloud, damaged bellows, short lifetime), but
e-cloud clearing electrodes successful in increasing threshold, and
..lot of work in 2013 for replacement/upgrade of old hardware in progress resume operation by this Summer
Effect of crab waist scheme
Design Goal
CRAB OFF
CRAB ON
Luminosity [1028 cm-2 s-1]
Luminosity [1028 cm-2 s-1]
Comparison of best runs with and without Crab-Waist
VEPP-2000, BINP, Round Beams
Round Beams Collisions
Round beams experiment:
geometrical factor gain
beam-beam limit enhancement
2 pairs of superconducting focusing solenoids in the 2 Interaction Regions symmetrically with respect to IPs
Several combinations of solenoid polarities satisfy Round Beams condition:
Normal Round (++ --)
Mbius (++ -+)
Double Mbius (++ ++)
Two Flat combinations (+- +- or +- - +) more simple and also satisfy RBC if the betatron tunes lie on the coupling resonance
n1 - n2 = 2
Small Dynamic Aperture
VEPP-2M data
Simulations
2010-2011 run, 2011-2012 run, 2012-2013 run
DA and IBS
lifetime
Flip-flop
Lack of e+
Luminosity vs Energy
BEPC-II, IHEP
Major upgrade of BEPC in 2004
Presently only existing t/charm
Luminosity tuning
Luminosity increased nx 0.5
Low ap lattice lower e and sz
The near Future
40 times higher luminosity
2.1x1034 --> 8x1035 cm-2s-1
KEKB to SuperKEKB
Colliding bunches
Nano-Beam scheme
extremely small by*
low emittance
Beam current double
Redesign the lattice to squeeze the emittance (replace short dipoles with longer ones, increase wiggler cycles)
Replace beam pipes with TiN-coated beam pipes with antechambers
New superconducting final focusing magnets near the IP
New e+ Damping Ring
Upgrade positron capture section
Upgrade to Belle II detector
e- 2.6A
e+ 3.6A
Injector Linac upgrade
DR tunnel
Improve monitors and control system
Low emittance
RF electron gun
Reinforce RF systems for
higher beam currents
28
K. AKAI, Progress in Super B-Factories, IPAC13
Intra-beam scattering is included.
Parameters of KEKB and SuperKEKB
29
K. AKAI, Progress in Super B-Factories, IPAC13
Eight final focus QCS with 40 corrector coils are to be used.
Fabrication of QCS-L started in July 2012, and will be completed in JFY2013.
Fabrication of QCS-R is scheduled in JFY2013 and 2014.
Prototype magnet was made at KEK. Test results show sufficient margin for operation.
Corrector coils are being wound at BNL under BNL/KEK collaboration.
Successfully tested without any quench up to 2157A, well over the design current (1560A) for nominal operation.
I4S/[email protected] = 62.8%
I12GeV/[email protected] = 87.0%
Sufficient margin for operation
QC1LE prototype magnet
Final focus SC quads (QCS)
30
K. AKAI, Progress in Super B-Factories, IPAC13
Commissioning Scenario
First target luminosity
1 x 1034 cm-2s-1
Baseline
Scenario
Phase 1
Jan. 2015 -
~5 months
Phase 2
~4 months
[Phase 1]No QCS, No Belle II
Basic machine tuning, Low emittance tuning
Vacuum scrubbing ( 0.5 ~ 1.0 A, >1 month)
DR commissioning start (~Apr. - )
[Phase 2]With QCS, With Belle II (without Vertex Detector)
Small x-y coupling tuning, Collision tuning
by* will be gradually squeezed
Background study
[Phase 3]With Full Belle II
Increase beam current with adding more RF
Increase luminosity
TOP
PXD/SVD ready
CDC
installation
Phase 3
31
K. AKAI, Progress in Super B-Factories, IPAC13
Commissioning Scenario
The possible Future
Super t/charm proposals
Italian Tau/CharmBINP Tau/CharmIHEP Tau/CharmTurkishCharm2 rings2 rings2 ringsLinac+ringLuminosity (cm-2s-1) 1 x 1035 1 x 1035 1 x 1035 1.4 x 1035Circumference (m)340360/800990250 (600?)Beam energy (GeV)1 2.30.5 231 + 3.56Emittance H (nm)53/101016Coupling (%)0.250.50.50.3IP b (x,y) (mm)70, 0.6200,0.6/20, 0.761000, 180, 5bb V tune shift0.64 0.080.0950.170.060.12Crab waistYESYESYESNOBeam current (A)1 1.71.8 1.72.70.48 + 4.8N. of bunches530418540125Italian t/Charm Factory
Evolution after cancellation of SuperB
Energy tunable in the range Ecm = 1-4.6 GeV
1035 cm-2 s-1 luminosity at the t/charm threshold and upper
Symmetric beam energies
Longitudinal polarization in the electron beam (60-70%)
Possibility of e-e- collisions (to be studied)
Design based on Large Piwinski angle & crab waist sextupoles collision scheme
Low beam emittance (about 2 nm natural)
Wigglers needed at lower beam energy
Injection system scaled from the SuperB one
Possibility to use injection Linac + additional C-band Linac for a 6 GeV SASE-FEL facility
t/charm parameters vs E
t/charm @Tor Vergata (former SuperB site)
Tau/Charm Accelerator Report just written (150 pp, not public yet)
Summary
Higher luminosity colliders can still be built, profiting from:
experience from past successes
new ideas
new technologies
synergy with other communities
A Super Factory is being built at KEK very important to keep alive this kind of Accelerators and Physics !
Several proposal for lower energy High Luminosity Flavour Factories on the market at different laboratories with experience of successful accelerators
Aknowledgments
For the material presented here Im indebted with:
K. Akai, Y. Funakhoshi, KEK
Q. Qing, Y. Zhang, IHEP
M. Zobov, INFN-LNF
A. Bogomiagkov, I. Koop, D. Schwartz, BINP
THANK YOU FOR YOUR ATTENTION
Spare slides
BINP Super cTau (2nd design)
Beam energy from 0.5 to 2.1 GeV
Peak luminosity 1035 cm-2s-1 at 2 GeV and within as wide as possible energy range
Circumference 366 m to fit in the existent tunnel of VEPP4-M (previous design 800m)
Conform as much as possible to existent infrastructure
Longitudinal polarization at some energy points
Parameters
Energy2.0 GeV1.5 GeV1.0 GeV0.5 GeVCircumference368 mBeta IP hor/ver20 cm / 0.6 mmEmittance hor/ver with ibs @ 0.5% coupling3.1 nm16 pm2.7 nm14 pm5.5 nm26 pm18 nm89 pmCrossing angle2x30 mradBunch length8 mm8 mm8 mm8 mmEnergy spread110-31.410-33.310-39.910-3RF frequency700 MHzHarmonic number864Particles in bunch3.2510103.1110103.7810103.531010Number of bunches418Total beam current1.8 A1.7 A2.1 A1.9 ABeam-beam parameter0.0950.130.170.17Luminosity11035110350.9810350.3610352 cm / 0.76 mm
10 nm
10 mm
Old C-Tau, 800m
71010
1.7 A
IHEP Super Tau-Charm Factory
Dual ring, factory like
2.5-3 GeV, parasitic 3rd generation SR source
Crab Waist collision scheme
Small IP b functions
Small emittance using wigglers
High beam current
Electron beam polarization (e- source, 5 Siberian Snakes)
Top-up injection at 3 GeV, 50 Hz
IHEP Super Tau-Charm Factory
Turkish Accelerator Complex (TAC) SCF
TAC SCF presented to ECFA 2011
Linac (e-) + ring (e+) charm factory with L= 1.41035 cm-2 s-1
Synchrotron light source based on positron ring
Free electron laser based on electron linac
TDR SCF@TAC will be completed in 2013
TAC Super Charm Factory parameters
Parametere--linace+-ringEnergy, GeV1.003.56Particles per bunch, 1010220 function at IP, mm80/580/5x/y/z, m/m/mm36/0.5/536/0.5/5Beam current (A)0.484.8Circumference, m600Crossing angle, mrad34Collision frequency, MHz150Luminosity, cm-2s-11.41035I+ I NharmonicNbunches
[A2]
I
+
I
-
N
harmonic
N
bunches
[A
2
]
I+ I NharmonicNbunches
[A2]
I
+
I
-
N
harmonic
N
bunches
[A
2
]
120*Amp2 /Nbunch
lum
inos
ity/1
e28
Luminosity vs Current Product
21/12/2008 SIDDHARTA
19/12/2011 Kloe2
18/04/2012 Kloe20
5000
10000
15000
20000
25000
30000
35000
40000
45000
0 0.25 0.5 0.75 1 1.25 1.5 1.75 2 2.25 2.5
120*Amp
2
/Nbunch
l
u
m
i
n
o
s
i
t
y
/
1
e
2
8
Luminosity vs Current Product
21/12/2008 SIDDHARTA
19/12/2011 Kloe2
18/04/2012 Kloe2
0
5000
10000
15000
20000
25000
30000
35000
40000
45000
00.250.50.7511.251.51.7522.252.5
120*Amp2 /Nbunch
lum
inos
ity/1
e28
Luminosity vs Current Product
21/12/2008 SIDDHARTA18/04/2012 KLOE2
12/04/2007 Finuda best16/09/2005 Kloe best06/08/2002 Kloe best
0
5000
10000
15000
20000
25000
30000
35000
40000
45000
0 0.25 0.5 0.75 1 1.25 1.5 1.75 2 2.25 2.5
120*Amp
2
/Nbunch
l
u
m
i
n
o
s
i
t
y
/
1
e
2
8
Luminosity vs Current Product
21/12/2008 SIDDHARTA
18/04/2012 KLOE2
12/04/2007 Finuda best
16/09/2005 Kloe best
06/08/2002 Kloe best
0
5000
10000
15000
20000
25000
30000
35000
40000
45000
00.250.50.7511.251.51.7522.252.5
Main Parameters of VEPP-2000
Circumference 24.38 mRF frequency 172 MHzRF voltage 100 kVRF harmonic number 14Momentum compaction 0.036Synchrotron tune 0.0035Energy spread 6.4 x 10-4
Beam emittances (in the round mode) 1.29 x 10-7 m radDimensionless damping decrements (x,y,s) 2.19 x 10-5, 2.19 x 10-5, 4.83 x 10-5
Betatron tunes 4.05, 2.05Betatron functions at IP 10 cmNumber of bunches per beam 1Number of particles per bunch 1 x 1011
Beam-beam parameter (x,y) 0.075, 0.075Luminosity per IP (at 1 GeV) 1 x 1032 cm-2s-1
(11031cm-2s-1 at 2E=1 GeV achieved, 21.01.2008)
Design Parameters
General Parameters
Beam energy 1.02.1 GeVOptimized beam energy 1.89 GeVLuminosity @ 1.89 GeV 1.01033 cm2s1Full energy injection(e+) 1.551.89 GeVDedicated SR operation 250 mA @ 2.5 GeV
Collision Parameters
Energy 1.89 GeV s 0.034Beam Current 910 mA p 0.024Bunch Current 9.8 mA z0 0.0135 mBunch Number 93 z 0.015 mRF Voltage 1.5 MV Emittance 144 nmrad x / y 1.0/0.015 m Coupling 1.5%x/y 6.53/5.58 y 0.04Crossing Angle 211 mrad x/y/z 3.0e4/3.0e4/1.5e4 turns
6 / 50
L = 2ere
1+ y*
x*
Iyy*
RLRy
L=
g
2er
e
1+
s
y
*
s
x
*
I
x
y
b
y
*
R
L
R
y
Parameter Units st20_55LUMINOSITY 1035 cm-2 s-1 1.0 1.0 0.2c.m. Energy GeV 4.6 4.0 2.0Beam Energy GeV 2.3 2.0 1.0Circumference m 340.7 340.7 340.7X-Angle (full) mrad 60 60 60Piwinski angle rad 11.19 10.84 14.66Hourglass reduction factor 0.86 0.85 0.83Tune shift x 0.004 0.004 0.002Tune shift y 0.078 0.089 0.064x @ IP cm 7 7 7y @ IP cm 0.06 0.06 0.06x @ IP microns 18.50 18.95 20.67y @ IP microns 0.086 0.088 0.096Coupling (full current) % 0.25 0.25 0.25Natural emittance x nm 3.76 2.85 1.42Emittance x (with IBS) nm 4.89 5.13 6.11Emittance y (with IBS) pm 12.2 12.8 15.3Natural bunch length mm 6 5 6Bunch length (with IBS) mm 6.9 6.9 10.1Beam current mA 1720 1745 1000Buckets distance # 1 1 1Ion gap % 2 2 2RF frequency Hz 4.76E+08 4.76E+08 4.76E+08Number of bunches # 530 530 530N. Particle/bunch # 2.3E+10 2.3E+10 1.3E+10Beam power MW 0.28 0.16 0.05Transverse damping times (x/y) msec 23/33 35/49 35/49