Webcast Seminar - CLASSE · e+e- Factory Overview 11/21/03 D. Rice 1 Webcast Seminar: ªThe seminar...
Transcript of Webcast Seminar - CLASSE · e+e- Factory Overview 11/21/03 D. Rice 1 Webcast Seminar: ªThe seminar...
e+e- Factory Overview 11/21/03 D. Rice 1
Webcast Seminar:The seminar to follow will be webcast as part of the Accessible Webcast Seminar (AWSem) program initiated at LEPP, Cornell.The seminar will run from approximately 1:15 PM to 2:30 PM EST Friday, 21 November, 2003.Please check www.lns.cornell.edu/public/COMP/AWSem/index.htmlfor instructions to access the seminar and related links.If you are connected to participate in the seminar please either sign into the REAP chat room on the LBNL Secure Messaging server, or send email to [email protected] that there is a ~20 second delay in broadcasting the seminar, so be prepared to refer back to a previous slide with your questions.If all else fails there is a speaker phone in the conference room at 607 255-3850 for brief comments or help only.
Overview of E+E- …or
Highlights of the Workshop on E+E- Factories (SLAC Oct. 13-16, 2003)
D. Rice11/21/2003
www-conf.slac.stanford.edu/icfa03/
e+e- Factory Overview 11/21/03 D. Rice 3
I. Facilities II. AP&Tech Issues
SC coil winding at BNLEC effectsFeedback systemsIR designBBI & ECICompensation of PC’s
Neg αP opticsStrong longitudinal focusingReliabilityInjection (trickle charging)
• PEP-II, KEKB• CESR-c• BEPC-II• DAΦNE• VEPP-2000• eRHIC
e+e- Factory Overview 11/21/03 D. Rice 4
B Factory Status – PEP-II (M. Sullivan)
Figure from J. Seeman
e+e- Factory Overview 11/21/03 D. Rice 5
e+e- Factory Overview 11/21/03 D. Rice 6
PEP-II records at the end of run 3 (June 2003)
e+e- Factory Overview 11/21/03 D. Rice 7
J. Seeman, Jun 03
PEP-II Collision Parameters
IP Parameter Design Peak performance (Jun 03)
C-M energy (GeV) (e+: 3.1 ; e-: 9.0) 10.58 10.58Crossing angle (mrad) 0.0 < 1.0Luminosity (x 1033/cm2/s) 3.00 6.57
Number of bunches 1658 1034LER current (mA, e+) 2146 1550HER current (mA, e-) 750 1175LER/HER current ratio 2.9/1 1.3/1
βy*/βx* (cm/cm) 1.5 / 50 1.2 / 40+, 1.2 / 28-Emittance (nm-rad) (y/x) 1.5 / 49 1.8 / 30+, 1.8 / 49-IP rms beam size σy/σx (µm) 4.7 / 157 4.6 / 113
LER tunes (x/y) 38.64 / 36.57 38.52 / 36.57HER tunes (x/y) 24.62 / 23.64 24.52 / 23.62Beam-beam parameter (vertical +/-) 0.03 0.082 / 0.040Beam-beam parameter (horizontal +/-) 0.03 0.109 / 0.040
e+e- Factory Overview 11/21/03 D. Rice 8
Forward Vertex Bellows – Before Cooling
T_VTX2 Thermocouple( dT = 105 F = 58 C)
Beryllium Vertex Chamber B1 Chamber
Hottest Point according to model (300 C)
e+e- Factory Overview 11/21/03 D. Rice 9
VTX Bellows Cooling Installation
e+e- Factory Overview 11/21/03 D. Rice 10
Elliptical Vacuum Valve Failure- Beam Time Lost 26.00 hours
LER Frangible Link - Beam Time Lost 47.50 hours
Mystery Pressure Bump Near IP - Beam Time Lost 15.50 hours
LER Arc 1 Pumping Chamber - Beam Time Lost 48.50 hours
Q2 Chamber - Beam Time Lost 50.1 hours
These five incidents contributed 187.6 of the 188.9 hours of downtime attributed to vacuum failures during the 2002-2003 PEP-II run
Vacuum Failures CausingMachine Downtime
e+e- Factory Overview 11/21/03 D. Rice 11
Summer 2003 Hardware Upgrades
♦Fixed the vacuum leak in IR2 septum chamber
♦Fix vacuum problem in LER arc 1
♦New RF station for HER in region 4 (4-1)
♦Modified all bpms in region 2 to be both x and y
♦Many improvements to RF systems in both rings
♦Added cooling to all LER bellows
♦Added more solenoid windings for LER
e+e- Factory Overview 11/21/03 D. Rice 12
PEP-II Goal for Jul 2004
June 03 Jul 2004LER energy 3.1 3.1 GeVHER energy 9.0 9.0 GeVLER current 1.45 2.7 AHER current 1.15 1.6 Aβy
* 12.0 9.0 mmβx
* 28 28 cmX emittance 50 40 nm-radEstimated σy
* 4.5 3.4 µmBunch spacing 1.89 1.26 mNumber of bunches 1034 1450Collision angle head-on head-on mradsBeam pipe radius 2.5 2.5 cmLuminosity 6.5×1033 1.2×1034 cm−2 sec−1
Director’s challenge to deliver another 100 fb-1 by Jul 2004
e+e- Factory Overview 11/21/03 D. Rice 13
♦ We need to further improve the HER and LER beta beats and move closer to the ½ integer in x.
♦ Increase the beam currents and the number of colliding bunches. This means going to a by2 colliding bunch pattern and learning to work with the tune shifts induced by the parasitic crossings.
♦ Understand and control the coupling in the IR
♦ Trickle injection for the LER
♦ Lower the βy* in both rings. We were somewhat successful with this in the HER but the bunch length of the HER is so long that we did not see much (if any) improvement in luminosity. This also means the bunch length will have to be smaller.
♦ Improve injection – better efficiency, less detector background, faster turnaround after a beam abort. If we can get the HER injection backgrounds low enough we will be able to try HER trickle injection.
♦ Minimize the number of beam aborts. Biggest effort is in the RF system. We want to reduce the number of beam aborts to less than one a day.
How do we achieve this?
This is probably overall the hardest
e+e- Factory Overview 11/21/03 D. Rice 14
Advanced B Factory with 952 MHz RF Frequency
• E+ = 8 GeV• E- = 3.5 GeV
βy* = 1.5 mm
βx* = 15 cm• Bunch length = 1.8 mm• Crossing angle = ~15. mrad• Beam-beam parameters = 0.15• N = 6900 bunches• L = 1.0 x 1036 cm-2s-1
• Site power with linac and campus = ~120 MW.
• I+ = 6.8 A• I- = 15.5 A
e+e- Factory Overview 11/21/03 D. Rice 15
B Factories – KEKB (Y. Funakoshi)
• Beam energy– 8GeV (electron)– 3.5GeV (positron)– Operated on Υ(4s)
• Circumference– ~3018m– Use TRISTAN tunnel
• RF system– fRF ~ 509MHz– ARES (LER)– ARES+SCC (HER)
• Injector Linac– Upgraded 2.5GeV -> 8GeV– No Damping rings– 2 bunch injection (e+)
e+e- Factory Overview 11/21/03 D. Rice 16
KEKB IR Design• Features
– Superconducting Quadrupole magnets– Compensation solenoid– Horizontal crossing angle
• Total crossing angle = 22mrad– Low-β
βx/βy = 33cm/1cm
e+e- Factory Overview 11/21/03 D. Rice 17
e+e- Factory Overview 11/21/03 D. Rice 18
KEKB Luminosity Records
206.3/pb/shift
579/pb/day
12.76/fb/month
158.7/fbTotal
1.05671034/cm2/secLpeak
Record valueunit
Ldt∫Ldt∫Ldt∫
Ldt∫
: integrated luminosity recorded by Belle Detector Ldt∫
e+e- Factory Overview 11/21/03 D. Rice 19
KEKB at 1034
1.057x1034 (1x1034)/cm2/secPeak luminosity
0.065/0.052(0.039/0.052)
0.096/0.069(0.039/0.052)
Beam-beam parameters ξx/ξy
58/0.7 (33/1)59/0.58 (33/1)cmBeta’s at IP βx/βy
44.512/41.580(47.52/43.08)
45.507/43.546(45.52/45.08)
Betatron tunes νx/νy
-0.0207-0.0249Synchrotron tune7.54 (2)nsecAveraged bunch spacing
0.818 (0.22)1.07 (0.52)mABunch current1284 (~5000)Number of bunches
1050 (1100)1377 (2600)mATotal beam current24 (18)18 (18)nmHorizontal emittanceHERLER
( ): design values
e+e- Factory Overview 11/21/03 D. Rice 20
KEKB Luminosity History
e+e- Factory Overview 11/21/03 D. Rice 21
Key Issues for KEKB
• The history of the KEKB commissioning has been tough fights against three major difficulties.– Fight against the high beam currents
• Troubles with hardware components• Instability
– Fight against the single beam blowup due to the electron cloud instability• Solenoid winding
– Fight against the beam-beam blowup• Tune survey• Optics corrections• Other tuning knobs (X-Y coupling at IP etc.)
e+e- Factory Overview 11/21/03 D. Rice 22
Examples of high current problems
Damaged RF-shield fingers in bellows due to HOM
Cu
Beam
10 mm
Direct damage by beam hit (Movable Mask)
e+e- Factory Overview 11/21/03 D. Rice 23
High beam currents - Instabilities• Instability
– Sources• Fast ion
– Serious with bad vacuum pressure– Can be suppress by bunch-by-bunch FB
• Electron cloud– Can be suppress by bunch-by-bunch FB
• RF cavity– Almost no instability due to RF cavities has given beam
current limitations.– We need -1 mode damper (with comb-filter) to suppress the
instability from the fundamental mode.– We do not need the longitudinal bunch-by-bunch FB.
• Others– Sometimes broken bellows etc. bring a serious transverse
instability.– Some unknown source of impedance brings a strong
horizontal instability in HER.
e+e- Factory Overview 11/21/03 D. Rice 24
Solenoid installation (anti-ECI)
0
400
800
1200
1600
2000
2400
2800
3200
Total length of solenoidT
otal
leng
th(m
)
Date
Sep. 00 Jan. 01 Apr. 01 Sep. 01 Jan. 02
Bz > 20 G
preliminary (very rough estimation)
total drift length
circumference
1st
2nd 3rd
4th 5th
e+e- Factory Overview 11/21/03 D. Rice 25
Effect of solenoids on vert. beam size
0
1
2
3
4
5
0 200 400 600 800 1000 1200 1400 1600
Ver
tical
bea
m si
ze@
IP (m
icro
n)
LER beam current (mA)
1 train, 1153 bunches, 4 rf bucket spacing
2001 July : on
2001 Dec. : on
2002 Feb. : on
2001 July : off
After last installation of solenoid, blowup was disappearedup to 1300mA.
Effect of solenoid in a physics fill pattern (4 rf buckets spacing)
e+e- Factory Overview 11/21/03 D. Rice 26
Suppression of B-B blowup
• Tune survey• Both Simulations and Surveys in real machine• Horizontal tunes very close to the half-integer• Need very fine control of tunes
• Optics correction (global correction)β functionsDispersionX-Y coupling
• Collision tuning knobs• Waist points• X-Y coupling at IP• Dispersions at IP• Orbit Feedback around IP
e+e- Factory Overview 11/21/03 D. Rice 27
Optics modeling & correction with SAD –Example – coupling & dispersion at IP
• X-Y coupling and dispersion at IP are adjusted by using a tuning knob.
• We do not use skew-quads for this purpose.
• Vertical bumps at 16 sextuples are used.
• Shift persons & operators frequently scan X-Y coupling parameters (R1,R2,R3,R4) and η and η’ @IP.
Find of an optimum value for R4 was one of the key points of recent progress in the KEKB luminosity.
e+e- Factory Overview 11/21/03 D. Rice 28
KEKB Upgrade
331010βy*[mm]
0.1~0.260.1~0.260.050.05ξy
3355σl [mm]
2~6 x 10351 x 1034L[/cm2/sec]
4.19.41.12.6I [A]HERLERHERLER
SuperKEKBKEKB (design)
~$30M+ /year 2004-2013
e+e- Factory Overview 11/21/03 D. Rice 29
Path to SuperKEKB
• High beam currents– Vacuum system– RF system
• Low β– IR design– Short bunch length
• High beam-beam parameters– Crab cavity
• Linac upgrade– C-band RF system
e+e- Factory Overview 11/21/03 D. Rice 30
Vacuum R&D• Ante-Chamber
– Without photon stops– Test model will be installed in
the next shutdown.
• “Finger-less” bellows chamber
A test model was installed in LER.Beam test will be done in the next run.
e+e- Factory Overview 11/21/03 D. Rice 31
Crab cavity developmentCrab crossing (+ horizontal tune close to the half-integer) may boost the
beam-beam parameter up to 0.2.
crossing angle 22 mrad
Head-on(crab)
◊
◊ ◊ ◊◊
ξy(Strong-weak simulation)
(Strong-strong simulation)
I.R. 20
I.R. 90
I.D. 188
I.D. 120
I.D. 30
I.D. 240
Input Coupler
Monitor Port
I.R.241.5
483
866Coaxial Coupler
scale (cm)
0 50 100 150
-> K. Ohmi
K. Hosoyama, et al
Superconducting crab cavities are under development, will be installed in KEKB in 2005.
e+e- Factory Overview 11/21/03 D. Rice 32
e+e- Factory Overview 11/21/03 D. Rice 33
Charm Factories - BEPC
III
III IV
e-
RFRF SR
e+
IP
North
e+e- Factory Overview 11/21/03 D. Rice 34
BEPC-II main parameters
Beam energy range 1–2.1 GeV
Optimized beam energy region 1.89GeV
Luminosity @ 1.89 GeV 1×10 33 cm-2s-1
Injection from linac Full energy injection: Einj=1.55−1.89GeV
Dedicated SR operation 250 mA @ 2.5 GeV
e+e- Factory Overview 11/21/03 D. Rice 35
BEPC-II IR layout – HEP mode
IR lattice consists of SCQ(RED), anti-solenoids(BLUE), ISPB, Q1a, Q1b. It has a doublet construction, the separated Q1a and Q1b function a focusing quadrupole. ISPB make the beams separate further. Anti-solenoids decouple the detector solenoid effects.
e+e- Factory Overview 11/21/03 D. Rice 36
BEPC-II IR layout- SR mode
For SR mode SCB(GREEN) will switch on, the beam will circulate in the outer ring.
e+e- Factory Overview 11/21/03 D. Rice 37
Computer modeling of BBI (Hirata w-s 6D)
Luminosity survey with a crossing angle of φc=11mrad 2
e+e- Factory Overview 11/21/03 D. Rice 38
Coupled bunch instabilities
12.8Long. (ms)
0.534.326.6Tran. (ms)
ECIFBIIResistiveHOM
Transverse instability much faster than SR Damping:feedback system required
Longitudinal instability same level as SR Damping:feedback system as a backup
For SR mode, bunch current and total beam current lower, instabilities weaker than colliding mode.
e+e- Factory Overview 11/21/03 D. Rice 39
Simulations of ECI growth time
0.00581.4001.2×10111.0660.001Ante+TiN+Clear.
0.0150.5303.5×10111.0660.001ante+TiN
0.810.0201.7×10131.0660.1TiN only
0.170.0403.1×10121.80.001With ante.
2.890.0036.2×10131.80.1No ante.
ϒτ (ms)EC ρ (m-3)SEYPEYmethod
With antechamber+TiN: Coupled bunch inst. damped by feedback,no TMCI instability occurs
e+e- Factory Overview 11/21/03 D. Rice 40
BEPC-II time line
• Linac upgrade May-Dec 2004• Long shutdown April 2005 – January 2006• Machine commissioning Feb.-Sept. 2006• Machine-detector tuning Nov. 2006-Feb. 2007• Physics starts March 2007
e+e- Factory Overview 11/21/03 D. Rice 41
M.E. Biagini, LNF-INFNon behalf of the DAΦNE Team
e+e- Factory Overview 11/21/03 D. Rice 42
DAΦNE Rings
KLOE
DEAR
e+
e-
FINUDA
C = 97 mE = 0.51 GeV (Φ)
e+e- Factory Overview 11/21/03 D. Rice 43
DAFNE Luminosity
2002DEAR & KLOE LUMINOSITY
Peak
Daily Integrated
Total Integrated
e+e- Factory Overview 11/21/03 D. Rice 44
KLOE Runs - 2002• Background and Lifetime Optimization- Lowered βx* (5.6m 2.7m)- Orbit Optimization - Old and New Scrapers Optimization - Sextupoles and Octupoles Optimization - Improved linear and non-linear knowledge of the machine - Increased Dynamic aperture (better βs on Sexts and Wigglers)
• Luminosity Optimization- New Working Point for e- : 0.11/0.15 (Qx/Qy)- Lowered βy* (3.0cm 2.6cm)- Lowered βx
* (5.6m 2.7m)- Decreased horizontal emittance (0.96mm 0.76mm)- Adiabatic Tuning
e+e- Factory Overview 11/21/03 D. Rice 45
DAΦNE Accel. Physics-LONGITUDINAL QUADRUPOLE INSTABILITYLONGITUDINAL QUADRUPOLE INSTABILITY
• It appears in both rings, at high currents but with different single bunch thresholds:~20% higher for e+
• e+ beam power spectrum with 100 bunches, 900mA, during collision
• Longitudinal feedback is able to control the instability
e+e- Factory Overview 11/21/03 D. Rice 46
DAΦNE Hardware activities - 2003
• FINUDA detector & IR Installation
• KLOE new IR installation
• Straight long sections and kickers modifications
• Scrapers modifications
• Bellows modifications
• Ion clearing electrodes modifications
• Wigglers modifications
• Pipe modifications for 3rd RF harmonic cavity
e+e- Factory Overview 11/21/03 D. Rice 47
New Interaction Regions
• New IRs for KLOE and FINUDA have modified optics (doublet configuration) in order to decrease the IP βfunctions and lattice chromaticity, optimize background rejection and new supports to provide variable quadrupole rotations, to operate at different detector magnetic fields (from 0 to maximum)
100 bunches operation should be possible in both IRs now
e+e- Factory Overview 11/21/03 D. Rice 48
Bellows Modifications
As found
After insertions of pins to straighten the copper bellows
e+e- Factory Overview 11/21/03 D. Rice 49
Wiggler Field ModificationsSextupole component
Old wiggler: reduction of the dynamic aperture due to:- Strong sextupole components (~x2 like)- Field roll off at large offsets (~x6 like)
e+e- Factory Overview 11/21/03 D. Rice 50
Wiggler mods & Dynamic Aperture
Off energy DA before Off energy DA after
e+e- Factory Overview 11/21/03 D. Rice 51
Optics Modifications• FINUDA & KLOE IR optics are now very similar:
- Lower horizontal emittance: 0.42 µm (0.77)- Lower β in the wigglers to minimize non linearities- βx*= 1.7 m (or less if necessary) to allow 100bunches operation
- βy*= 27 mm, just about equal to the bunch length- Additional sextupoles in wigglers and at septum- Phase advance between the sextupoles optimized- Low beam invariants (H) to minimize background- Straight sections optimized for injection efficiencyand DA
- Predicted lifetime >3hrs at 2x1030 s.b. luminosity(with 20mA)
e+e- Factory Overview 11/21/03 D. Rice 52
Performance Goals for KLOE & FINUDA
• 100-110 bunches collisions operation
• 2 A/beam (asymptotically in 2 year)
• 2x1030 single bunch luminosity (at 20 mA, with present WP, linear extrapolation of obtained results)
• >1h lifetimes (at 2 Amps and 2x1032) (MAD predicts >3h)
• 10pb-1/day, 200pb-1/month, 1.0fb-1/0.5years delivered
• Goals based on extrapolations of 2002 results and the new low-β IRs. All other upgrades are meant just as safety margins
e+e- Factory Overview 11/21/03 D. Rice 53
DAΦNE beyond 2006
Currently under studies are two options for the future of DAΦNE, with major modifications needed:
1) Increase maximum Ecm from 1.4 GeV to >2.2GeV
2) Increase luminosity by >100 w.r.t. 2002-2005best performances, possibly in the 1034-1035 range
A joint Physics & Accelerator Workshop was held in Alghero last September to study the feasibility and
the physics case (C.Biscari’s & A. Gallo’s talks)
e+e- Factory Overview 11/21/03 D. Rice 54
Φ Factory – VEPP-2000
ILU3 MeVLinac
B-3M200 MeVsynchro-betatron
BEPe,e
booster–+
900 MeVSND
CMD-2
ee– +→convertor
2 m2 m
♦ E ≈ 1 GeV (per beam)♦ L ≈ 1×1032 cm-2 sec-1 (1×1 bunch)
e+e- Factory Overview 11/21/03 D. Rice 55
Realization of Round Beams
(A.Burov, S.Nagaitsev, Ya.Derbenev, FERMILAB-Pub-01/060-T)
Touschek problem for low energy:worse life time!
Conversion of conventional machine using beam adapters
e+e- Factory Overview 11/21/03 D. Rice 56
View of Collider
e+e- Factory Overview 11/21/03 D. Rice 57
VEPP-2000 Lattice
e+e- Factory Overview 11/21/03 D. Rice 58
Weak-Strong BB Simulation
0
1
2
3
4
5
6
0 0.05 0.1 0.15 0.2 0.25
Em
ittan
ce (
10-7
m r
ad)
ξ
12
strong-strong0
0.5
1
1.5
2
2.5
3
0 0.05 0.1 0.15 0.2 0.25
Em
ittan
ce (
10-7
m r
ad)
ξ
12
Emittance of the weak beam vs. the beam-beam parameter. Sextupoles off.
Emittance of the weak beam vs. the beam-beam para-
meter. Sextupoles on.
e+e- Factory Overview 11/21/03 D. Rice 59
Strong-Strong BB Simulation
Macroparticles/bunch Np = 50000, transverse
mesh 128x128;Field calculated via
FFT(K.Ohmi, Phys. Rev. E
59, 7287 (2000))Comparison of the sextupoles on
and off options.
e+e- Factory Overview 11/21/03 D. Rice 60
Main Parameters of VEPP-2000
Parameter Value Circumference 24.38 mRF frequency 172 MHzRF voltage 100 kVRF harmonic 14Momentum compaction 0.036Synchrotron tune 0.0035Energy spread 4104.6 −×Beam emittances (x,y) 71029.1 −× m radDimensionless damping decrements (x,y,z) 51019.2 −× , 51019.2 −× , 51083.4 −×Betatron tunes 4.05, 2.05Betatron functions @ IP 10 cmParticles per bunch 11101×Beam-beam parameter (x,y) 0.075, 0.075Luminosity per IP (at 1GeV) 1232101 −−× scm
e+e- Factory Overview 11/21/03 D. Rice 61
2.4 T Dipole Magnet
e+e- Factory Overview 11/21/03 D. Rice 62
Single Mode RF Cavity (172 MHz)
e+e- Factory Overview 11/21/03 D. Rice 63
13.0 T Solenoid
e+e- Factory Overview 11/21/03 D. Rice 64
Linac and Positron Source
debuncher
Damping ring
To VEPP-2000
electron gun
subharmonic target
linac
to VEPP-4
300 MeV linac
photo-gun
e+e- Factory Overview 11/21/03 D. Rice 65
Magnet Installation - VEPP-2000
e+e- Factory Overview 11/21/03 D. Rice 66
VEPP-2000 Summary
♠ Start of VEPP-2000 construction – January 2000
♠ Dipole, quads, sextupoles, skew-quads, steering coils, 6 from 8 vacuum chamber are ready, tested and installed
♠ 13 T field is achieved in solenoid prototype
♠ Weak-strong and strong-strong simulation show high ξ for the round beams
♠ Construction of transfer line from e+ source is going on
♠ Beam → at the end of 2004
e+e- Factory Overview 11/21/03 D. Rice 67
eRIHC (D. Wang)
• New kinematic region
• Ee = 5-10 GeV• Ep = 30 – 250 GeV• Sqrt(s) = 20 – 100 GeV
• Kinematic reach of eRHICx = 10-4 0.6Q2 = 0 104 GeV
• High LuminosityL ~1033 cm-2 sec-1
e+e- Factory Overview 11/21/03 D. Rice 68
eRHIC Design Goals
• Particle specieslepton: e- and e+hadron: proton, gold ion Au(A=197, Z=79)
• Beam energylepton: 5~10 GeVhadron: 25(?)~250 GeV for proton, 100 GeV/n for Au
• Luminositye-p collision: 1E32~1E33 cm-2s-1
e-Au collision: 1E30~1E31 cm-2s-1
• Longitudinal Polarizationlepton: e-, 5~10 GeV, e+, 10 GeV,proton: up to 250 GeV
• Particle specieslepton: e- and e+hadron: proton, gold ion Au(A=197, Z=79)
• Beam energylepton: 5~10 GeVhadron: 25(?)~250 GeV for proton, 100 GeV/n for Au
• Luminositye-p collision: 1E32~1E33 cm-2s-1
e-Au collision: 1E30~1E31 cm-2s-1
• Longitudinal Polarizationlepton: e-, 5~10 GeV, e+, 10 GeV,proton: up to 250 GeV
e+e- Factory Overview 11/21/03 D. Rice 69
Beam-beam Parameters
Beam-beam parameter assumption in ZDR stage of eRHIC design:0.005 for hadron beams 0.05 for lepton beamsin both planes, for both round and flat beams
In leptonIn lepton--hadronhadron collidercollider,,non-round beam will causeasymmetric horizontal/vertical beambeam parameters.
For For hadronhadron beam:beam:if beam is made hori. flathorizontal tune-shift is larger
For lapton beam: if it is hori. flat (e_x>>e_y), vertical tune-shift is larger
e.g., HERA
Beam sizes are matched
)(2
)(2
,
,,
,
,,
ey
ex
eyx
iyx
i
eiiyx
iy
ix
iyx
eyx
e
ieeyx
ZNr
ZNr
σσσβ
πγξ
σσσβ
πγξ
+=
+=
e+e- Factory Overview 11/21/03 D. Rice 70
Main parameters of 10 GeV ring
MW3.865.13Total radiation power27.18/21.2129.13/22.16Tunes
-47/-41-57/-50Natural chromaticities
cm-2 s-12.7E321E33Luminosity 0.025/0.050.05/0.05Beam-beam parameters
m10.6510.65Bunch spacing2.0E-31.8E-3Momentum compaction
ms7.47.4Damping time (long.)
kW/m6.49.6Synchrotron radiation density
MeV11.411.4Energy lossnm.rad50/1223/23Emittance
m0.19/0.190.1/0.1Beta at IPmA340450Total current
6.7E101E11N of particles per bunchGeV1010Beam energy m1277.91277.9Circumference
Flat beamRound beam
e+e- Factory Overview 11/21/03 D. Rice 71
Dynamic ApertureVery preliminary, trying to get benchmarked with LEGO and SADRound beam: not shown here as IR is not fully realistic yet. About ring
optics, DA not too bad as thought, even with 400m beta at IR. SAD(A. Obetov) seems to give better results than MAD.
Flat beam: just start, bare lattice, 3(v) and 2(h) sextupole families little tune scan, no local correction, etc.on-momentum, seems fineoff-momentum, far from optimization, chromatic effects, etc.
F. Wang
e+e- Factory Overview 11/21/03 D. Rice 72
eRHIC Summary• Lattice design of e-ring for eRHIC is making significant
progress recently. ZDR is going to be done soon.• A lot of interesting topics in this high luminosity,
polarized and multi-mode lepton ring design.• A workable solution with flat beam is found to meet the
basic requirement in IR geometry and SR issue. Likely we can push it further by learning from other factories.
• Spin rotators are embedded in lattice. Polarization looks promising so far.
• Arc lattice is flexible, DA is yet to be studied in detail.• For round beam scheme, still long way to go.
e+e- Factory Overview 11/21/03 D. Rice 73
Accelerator Physics & Technology
• Many good talks and discussion on current AP & tech issues as well as new ideas for future factories.
• Plenary talks:– B. Parker – BNL direct wind SC IR magnets– G. Stupakov – CSR effects in e+e- storage rings– K. Ohmi –Summary of beam-beam effects– K. Harkay – Observations of ECI– J. Fox – Bunch-by-bunch feedback systems
e+e- Factory Overview 11/21/03 D. Rice 74
AP & Technology (a later talk?)
• Working group topics– Optics analysis– IR design– BBI simulation– Combined BB & EC effects– Longitudinal instabilities associated with EC– Compensating PC’s with e-m lenses– RF upgrades – SC cavities, harmonic cavities– Collective effects– Operational reliability– Trickle injection in PEP-II– Strong RF focussing– Negative momentum compaction optics
www-conf.slac.stanford.edu/icfa03/
e+e- Factory Overview 11/21/03 D. Rice 75
BBI & EC (F. Zimmermann)
SummaryBeam-beam interaction introduces Gaussian variation of betatron tune along the bunch. Simulations show that thisaddt’l tune variation enhances e-cloud instability.
We developed an analytical model, where a bunch consists of 3 or 4 particles, electron cloud is represented by constantwake and by linear tune shift along the bunch, andbeam-beam by parabolic tune shift.
Model shows that beam-beam tune shift acts destabilizing
Agreement between model and simulation seems to improvewith increasing number of particles.
e+e- Factory Overview 11/21/03 D. Rice 76
Trickle Charging PEP-II (U. Wienands)
e+e- Factory Overview 11/21/03 D. Rice 77
The one-turn transfer matrix can be put in canonical form:
( )
−−
⋅+
⋅=⋅+⋅=+
ll
llJILssMαγβα
µµµµ sin1001
cosˆsinˆcos, with:
( )
Ls
LsR
LsRLs
LsRs
cl
cc
cl
cl
αµµγ
ααµ
µαβ
αµµα
2sin
cos1)(
)(1)(2cos11sin
)(
)(21sin
cos1)(
5656
56
−=
−−−=
−
−=
Since γl does not depend upon s, the vertical size of the ellipse (i.e. the normalized energy spread σE/E of the equilibrium distribution) does not vary along the ring. The longitudinal emittance εl is related to σE/E according to:
( )( )
cos12sin/ 2 LE
E cElllE α
µµσεγεσ
−==>=
Strong RF FocussingA. GalloA. Gallo,, The Strong RF Focusing: a possible approach to get short buncheThe Strong RF Focusing: a possible approach to get short bunches at the IPs at the IP
e+e- Factory Overview 11/21/03 D. Rice 78
Database of e+e- collider parameters (M. Biagini) is available on the High Luminosity e+e- Collider working group’s web page:
http://www.lnf.infn.it/icfa/
End