Background characterization: MD plan

1. Background characterization: MD plan W. Kozanecki • MD goals • Background sources & parametrization • Operational procedures • Open questions

2. MD goals • Characterize beam-current dependence of • machine-induced backgrounds • all BaBar ‘detectors’: SVT, DCH, EMC, DIRC, IFR + TRG, ODF • dedicated background monitors (pins, CsI counters, collim. BLMs) • beam-beam performance (& backgrounds) • specific luminosity • vertical & horizontal spot sizes in LER & HER • loss rates @ collimators in PR12 (HER), PR04 + PR02 (LER)

3. Proposed baseline parametrization B = BP + BL + Bbb + BHbg + BLbg + BLHbg + BI [+ BLT] = BP(from no-beam data) + dP * L (from colliding-beam data) + Bbb (IbL, IbH) (from colliding-beam data) + aH*IH + bH*IH2 + cH*IH4 (from single-beam HER data) + aL*IL + bL*IL2 + cL*IL4 (from single-beam LER data) + cLH * IL * IH (from 2-beam, non-colliding ?) + BI (differential, trickle – coasting ?) [+ BLT] (LER only, vary VRF?)

4. Proposed baseline parametrization B = BP + BL + Bbb + BHbg + BLbg + BLHbg + BI [+ BLT] = BP(from no-beam data) + dP * L(from colliding-beam data) + Bbb (IbL, IbH) (from colliding-beam data) + aH*IH + bH*IH2 + cH*IH4 (from single-beam HER data) + aL*IL + bL*IL2 + cL*IL4 (from single-beam LER data) + cLH * IL * IH(from 2-beam, non-colliding ?) + BI(differential, trickle – coasting ?) [+ BLT](LER only, vary VRF ?)

5. Data: Jan 04 (bef. therrmal outgassing crisis) Background characterization measurements Step 1: Beam-current scans  single-beam terms

6. Data: Jan 04 • Total occupancy • HER single beam • LER single beam • Beam-beam term • present in all subdetectors • reproducibility! Step 2: L & beam-beam terms EMC cluster multiplicity SVT occupancy (FL1 M01-f)

7. Proposed operational procedure: general guidelines • BaBar taking data! • Perturb as adiabatically as possible • start with stable machine in delivery mode • avoid acrobatics (delivery  collisions bkg  pedestals  single-beam  non-colliding  pedestals) • At each current setting • optimize tunes • on luminosity (in collision, coasting so lifetime reasonable) • on lifetime (single beam, minimize Touschek for beam-gas measurement) • reset vertical IP angles in both rings • check SLM, SXM & interferometer settings • start a new run (also at trickle-coasting transition) • Pedestal runs • no beam • Reproducibilty: if beam(s) lost, redo last setting

9. Time request • 2 components • setup & tuning: hard to estimate - make appropriate arrangements! • at least 5' per setting when changing only 1 beam current (requires BaBar shifter "on the ball") • first setup, state changes & aborts more time-consuming (need MCC ops "on the ball") • Babar data taking • in 2004: 7' per setting (no trickle), dominated by pin-diode stabilization needs • can we shorten it? • what do diamonds need? • what does data taking need? • what do pin diodes need? • From actual experience • in 2004: • planned 8h for data taking & BBR transitions only (w/o setup & mishaps) • used 16 h, but with more complicated procedure • 2006 request: comparable DAQ time  RQ 2 shifts (8:30 am - 12 am) • recovery should be easier than from an acc. phys. MD

10. To be clarified • Prerequisites • stabilized vacuum • in particular: is PR02 NEG 8020 really quiet ? • Babar encouraged to sample single-beam data whenever possible in the next few days (+ analyze it quickly) • ‘routine’ running in LER & HER with fulll RF complement • decent stored-beam & trickle backgrounds during preceding owl shift • Minimize data-taking time • diamond/diode settling time? • best trigger rmix to enhance background fraction ? • When (not) to trickle? • Need volunteer(s) to analyze data - incl. CsI & BLM!

11. Spare slides

12. Proposed operational procedure: colliding beam measurements • Setup: save configs & orbits; check fbcks; change BBR L1 config. • Keep IL ~ constant, vary IH (> 0.25 A, 0.25 A steps) • 2 regimes (to help separate Lumi & beam-beam contributions) • IL ~ 1.6 A (60% of peak LER current, moderate beam-beam) • no trickle (coast during data taking, trickle LER back up while filling HER) • ~ 7’ steps (dominated by pin-diode stability?) • IL ~ 2.7 A (or max. LER current that can be sustained stably) • to measure trickle contribution differentially, for each HER current setting: • trickle LER + HER (~ 5’) • coast LER + HER (~ 5’) • Keep IH ~ constant, vary IL (> 0.30 A, 0.35 A steps) • 2 regimes (to help separate Lumi & beam-beam contributions) • IH ~ 1.0 A (60% of peak HER current, moderate beam-beam) • no trickle (coasting during data taking, trickle HER back up when filling LER) • IH ~ 1.6 A (or max. sustainable HER current, assuming full RF complement) • to measure trickle contribution differentially, for each LER current setting: • trickle LER + HER (~ 5’) • coast LER + HER (~ 5’) • Pedestal run

13. Proposed operational procedure: single-beam measurements • Vary IH : 0.25-1.6 A, 0.25 A steps, no LEB • no trickle at low current, 7’ per setting • at topmost (or 2 topmost) HER current(s), trickle then coast (5+5') • Vary IL : 0.3-2.7 A, 0.35 A steps, no HEB • no trickle at low current , 7’ per setting • at topmost (or 2 topmost) LER current(s), trickle then coast (5+5') • Reproducibility check on single beam scans (esp. pins) • repeat middle & top points of previous two scans (HER, then LER) • Non-colliding scan (sparse) • Keep IH ~ constant (1.35 A), vary IL (> 0.30 A, 0.6 A steps) • Keep IL ~ constant (2.35 A), vary IH (> 0.25 A, 0.5 A steps) • Operational aspects • Separate beams: X = 2 * 1 mm, Y = 2 * 400 microns ? • 7’ per setting, no trickle (measure HEB lifetime change) • Pedestal run

14. Total time estimates (ONLY data taking + BBR on-off): 690' • Setup 15’ • Collision scan @ fixed LER current 160’ • IL = 1600 mA, vary IH 7 x 10’ • IL = 2700 mA , vary IH 7 x 13’ • Collision scan @ fixed HER current 190’ • IH = 1000 mA , vary IL 8 x 10’ • IH = 1600 mA , vary IL 8 x 13’ • Pedestals 5’ • HER single-beam scan 5 x 10’ + 2 x 13' 80’ • LER single-beam scan 6 x 10’ + 2 x 13' 90’ • Repeat middle & top points of single-beam scans (H, L) 50’ • Non-colliding scans 90’ • IH = 1350 mA , vary IL 5 x 10’ • IL = 2350 mA , vary IH 4 x 10’ • Pedestals 5’

15. Background sources • Luminosity (radiative-Bhabha debris) – major concern (DCH future) • BP ~ dP * L (strictly linear with L) • Beam-beam tails • from LER tails: BL, bb ~ bL,bb*IL + fL(xL,H+/-) • from HER tails: BH, bb ~ bH,bb*IH + fH(xL,H+/-) • Beam-gas (bremsstrahlung + Coulomb) • HEB only: BHbg ~ aH*IH + bH*IH2 (aH , bH > 0) • LEB only: BLbg ~ aL*IL + bL*IL2 (aL , bL > 0) • beam-gas cross term: BLHbg ~ cLH * IL * IH (LEB+HEB, out of collision) • BI: LER injection (trickle) background • BLT (exp. signature somewhat similar to bremsstrahlung)

16. Proposed operational procedure: colliding beam measurements (1) • 2000 & 2002 procedure: