Recent PEP-II/BaBar Operational Parameters

1. Recent PEP-II/BaBar Operational Parameters W. Kozanecki, CEA-Saclay • Beam currents, luminosity, bunch pattern • Typical backgrounds • integrated dose • beam aborts • stored-beam backgrounds • trickle backgrounds • Collimation • Vacuum history • Heating issues

2. Luminosity Run 4 Beam-current & Luminosity History LER total current HER total current

5. J. Seeman, Apr 04 PEP- II Collision Parameters (Apr 04) IP ParameterDesignPeak performance Apr 04 C-M energy (GeV) (e+: 3.1 ; e-: 9.0) 10.58 10.58 Crossing angle (mrad) 0.0 < 1.0 Luminosity (x 1033/cm2/s) 3.00 8.33 Number of bunches 1658 1549 LER current (mA, e+) 2146 2230 HER current (mA, e-) 750 1380 LER/HER current ratio 2.9/1 1.6/1 by*/bx* (cm/cm) 1.5 / 50 1.1 / 48+, 1.1 / 28- Emittance (nm-rad) (y/x) 1.5 / 49 1.0 / 30+, 1.3 / 59- LER tunes (x/y) 38.64 / 36.57 38.52 / 36.56 HER tunes (x/y) 24.62 / 23.64 24.52 / 23.62 Beam-beam parameter (vertical +/-) 0.03 0.067 / 0.046 Beam-beam parameter (horizontal +/-) 0.03 0.086 / 0.032

6. HER trickle starts Run-4 radiation dose-rate history HER trickle starts Outgassing storms

7. Integrated-dose history

8. Stable-beam “genuine” radiation aborts: • 0.9 / day • ~ 60% of these may actually be sympathetic • “Genuine” injection aborts: 0.4 / day ...to be compared to an average of 7 aborts/day from all sources

9. IDCH, msrd/pred Normalized DCH current Stored-beam background history 20% 20% SVT ocp’cy @ f = p (HEB-sensitive) SVT ocp’cy @ f = 0 (LEB-sensitive) 10%

10. Trickle-injection background Veto windows • The background generated by the trickle injection is concentrated in a narrow time window corresponding to revolutions of the injected bunch. • BABAR vetoes this window during data taking to avoid high dead time • BABAR rejects a larger region at the analysis phase to guarantee good data quality. • The total loss is around 1.5%

11. HER collimators LER collimators Collimation • LER collimators • PR04: 4 fixed: x,y,x,y (orbit bumps) • horizontal collimators useful to reduce beam-beam background. • vertical collimators sometimes help with the LER trickle backgrounds. • PR02: 2 adjustables (x) • a major source of HOM heating. • can help with beam-beam tails in some subdetectors, but at the cost of swamping the IFR (and sometimes the DCH) with secondaries, so we use them very little move them elsewhere ? • HER collimators • PR12: 5 fixed: x,y,x,y,E • occasionally useful  trickle, beam-beam • PR02: 2 adjustable (x) • not useful

12. Ring-averaged presssure (Jul 2000, from inverse lifetime) 2004: <p> < 0.9 nT @ 1 A

13. Near-IR vacuum history LER current Incoming e+ (7 m from IP, LEB-sensitive ) Incoming e- (17 m from IP, HEB-sensitive ) Outgoing e+ (7 m from IP, L+HEB-sensitive )

14. 12 hours Thermal time constants: a problem! VGCC3027  (incoming LEB) BE diamond  (LEB sensitive) LER current VGCC2187 (HER sensitive)  BW diamond [+ BBR dead time] (HEB sensitive)

15. LER NEG temperatures 3027 = 268°F 3044 = 453°F LER current 2.2 A #2 #1 #3 #4 3081 = 724°F 3053 = 425°F

16. IR Heating Issues - Overview • HOM Heating • Vertex Bellows Cooling Addition 2002 is working well • Q1/Q2 Bellows • Larger HOM absorbers in 2002, • Cooling and monitoring improved. • Will need to improve HOM/Power capability - now 10 KW • Synchrotron Radiation and Orbit Constraints • Require LEB aimed at Luminosity Monitor • IP angles constrained by backgrounds • LEB B1 Fan Hits LEB Leg of Q2 Crotch and Q4 chamber • May be cause of magnet motion (~20 microns). • HEB – B1 fan aimed at High Power Dump must miss Q5R chamber flange • Vacuum and Backgrounds • HOM Heating of NEG and Increased Backgrounds

17. Spare slides

18. Near IR