Webcast Seminar: The seminar to follow will be webcast as part of - PowerPoint PPT Presentation

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.html for 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 dhr@cesr10.lns.cornell.edu � Note 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. e+e- Factory Overview 11/21/03 D. Rice 1

Overview of E+E- … or Highlights of the Workshop on E+E- Factories (SLAC Oct. 13-16, 2003) D. Rice 11/21/2003 www-conf.slac.stanford.edu/icfa03/

I. Facilities II. AP&Tech Issues SC coil winding at BNL • PEP-II, KEKB EC effects • CESR-c Feedback systems • BEPC-II IR design • DA Φ NE BBI & ECI • VEPP-2000 Compensation of PC’s • eRHIC Neg α P optics Strong longitudinal focusing Reliability Injection (trickle charging) e+e- Factory Overview 11/21/03 D. Rice 3

B Factory Status – PEP-II (M. Sullivan) Figure from J. Seeman e+e- Factory Overview 11/21/03 D. Rice 4

e+e- Factory Overview 11/21/03 D. Rice 5

PEP-II records at the end of run 3 (June 2003) e+e- Factory Overview 11/21/03 D. Rice 6

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 10.58 Crossing angle (mrad) 0.0 < 1.0 Luminosity (x 10 33 /cm 2 /s) 3.00 6.57 Number of bunches 1658 1034 LER current (mA, e + ) 2146 1550 HER current (mA, e - ) 750 1175 LER/HER current ratio 2.9/1 1.3/1 β y */ β x * (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 σ y / σ x ( µ m) 4.7 / 157 4.6 / 113 LER tunes (x/y) 38.64 / 36.57 38.52 / 36.57 HER tunes (x/y) 24.62 / 23.64 24.52 / 23.62 Beam-beam parameter (vertical +/-) 0.03 0.082 / 0.040 Beam-beam parameter (horizontal +/-) 0.03 0.109 / 0.040 e+e- Factory Overview 11/21/03 D. Rice 7

Forward Vertex Bellows – Before Cooling Hottest Point according to model (300 C) T_VTX2 Thermocouple ( dT = 105 F = 58 C) Beryllium Vertex Chamber B1 Chamber e+e- Factory Overview 11/21/03 D. Rice 8

VTX Bellows Cooling Installation e+e- Factory Overview 11/21/03 D. Rice 9

Vacuum Failures Causing Machine Downtime 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 e+e- Factory Overview 11/21/03 D. Rice 10

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 11

PEP-II Goal for Jul 2004 June 03 Jul 2004 LER energy 3.1 3.1 GeV HER energy 9.0 9.0 GeV LER current 1.45 2.7 A HER current 1.15 1.6 A β y * 12.0 9.0 mm β x * 28 28 cm X emittance 50 40 nm-rad Estimated σ y µ m * 4.5 3.4 Bunch spacing 1.89 1.26 m Number of bunches 1034 1450 Collision angle head-on head-on mrads Beam pipe radius 2.5 2.5 cm cm −2 sec −1 6.5 × 10 33 1.2 × 10 34 Luminosity Director’s challenge to deliver another 100 fb-1 by Jul 2004 e+e- Factory Overview 11/21/03 D. Rice 12

How do we achieve this? ♦ 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 β y * 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. This is probably overall the hardest ♦ 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. e+e- Factory Overview 11/21/03 D. Rice 13

Advanced B Factory with 952 MHz RF Frequency • E + = 8 GeV • I+ = 6.8 A • E - = 3.5 GeV • I- = 15.5 A * = 1.5 mm � β y � β x * = 15 cm • Bunch length = 1.8 mm • Crossing angle = ~15. mrad • Beam-beam parameters = 0.15 • N = 6900 bunches • L = 1.0 x 10 36 cm -2 s -1 • Site power with linac and campus = ~120 MW. e+e- Factory Overview 11/21/03 D. Rice 14

B Factories – KEKB (Y. Funakoshi) • Beam energy – 8GeV (electron) – 3.5GeV (positron) Operated on Υ (4s) – • Circumference – ~3018m – Use TRISTAN tunnel • RF system – f RF ~ 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 15

KEKB IR Design • Features – Superconducting Quadrupole magnets – Compensation solenoid – Horizontal crossing angle • Total crossing angle = 22mrad – Low- β ฀ β x / β y = 33cm/1cm e+e- Factory Overview 11/21/03 D. Rice 16

e+e- Factory Overview 11/21/03 D. Rice 17

KEKB Luminosity Records unit Record value L peak 1.0567 10 34 /cm 2 /sec ∫ Total /fb 158.7 Ldt ∫ /fb 12.76 Ldt /month ∫ /day /pb 579 Ldt ∫ Ldt /shift /pb 206.3 ∫ Ldt : integrated luminosity recorded by Belle Detector e+e- Factory Overview 11/21/03 D. Rice 18

KEKB at 10 34 LER HER Horizontal emittance nm 18 (18) 24 (18) Total beam current mA 1377 (2600) 1050 (1100) Number of bunches 1284 (~5000) Bunch current mA 1.07 (0.52) 0.818 (0.22) Averaged bunch spacing nsec 7.54 (2) Synchrotron tune -0.0249 -0.0207 Betatron tunes 45.507/43.546 44.512/41.580 ν x/ ν y (45.52/45.08) (47.52/43.08) Beta’s at IP β x/ β y cm 59/0.58 (33/1) 58/0.7 (33/1) Beam-beam parameters 0.096/0.069 0.065/0.052 ξ x/ ξ y (0.039/0.052) (0.039/0.052) 1.057x10 34 (1x10 34 ) Peak luminosity /cm 2 /sec ( ): design values e+e- Factory Overview 11/21/03 D. Rice 19

KEKB Luminosity History e+e- Factory Overview 11/21/03 D. Rice 20

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 21

Examples of high current problems Damaged RF-shield fingers in bellows due to HOM Beam Direct damage by beam hit (Movable Mask) 10 mm Cu e+e- Factory Overview 11/21/03 D. Rice 22

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 23

Solenoid installation (anti-ECI) Total length of solenoid preliminary (very rough estimation) 3200 circumference 2800 2400 total drift length 4th 5th 2000 Total length(m) 1600 3rd 2nd 1200 1st Bz > 20 G 800 400 0 Sep. 00 Jan. 01 Apr. 01 Sep. 01 Jan. 02 e+e- Factory Overview 11/21/03 D. Rice 24 Date