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Background characterization: MD plan. W. Kozanecki. MD goals Background sources & parametrization Operational procedures Open questions. MD goals. Characterize beam-current dependence of machine-induced backgrounds all BaBar ‘detectors’: SVT, DCH, EMC, DIRC, IFR + TRG, ODF - PowerPoint PPT Presentation
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W. Kozanecki MDI & PEP-II BBR meetings, 5 May 06
Background characterization: MD planBackground characterization: MD plan
MD goalsMD goals
Background sources & parametrizationBackground sources & parametrization
Operational proceduresOperational procedures
Open questionsOpen questions
W. Kozanecki
W. Kozanecki MDI & PEP-II BBR meetings, 5 May 06
MD goalsMD goals
Characterize beam-current dependence ofCharacterize 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)
W. Kozanecki MDI & PEP-II BBR meetings, 5 May 06
Proposed baseline parametrizationProposed baseline parametrization
B = BP + BL + Bbb + BHbg + BLbg + BLHbg + BI [+ BLT]
= BP (from no-beam data)
+ dP * L (from colliding-beam data)
+ Bbb (IbL, Ib
H) (from colliding-beam data)
+ aH*IH + bH*IH2 + cH*IH
4 (from single-beam HER data)
+ aL*IL + bL*IL2 + cL*IL
4 (from single-beam LER data)
+ cLH * IL * IH (from 2-beam, non-colliding ?)
+ BI (differential, trickle – coasting ?)
[+ BLT ] (LER only, vary VRF?)
W. Kozanecki MDI & PEP-II BBR meetings, 5 May 06
Proposed baseline parametrizationProposed baseline parametrization
B = BP + BL + Bbb + BHbg + BLbg + BLHbg + BI [+ BLT]
= BP (from no-beam data)
+ dP * L (from colliding-beam data)
+ Bbb (IbL, Ib
H) (from colliding-beam data)
+ aH*IH + bH*IH2 + cH*IH
4 (from single-beam HER data)
+ aL*IL + bL*IL2 + cL*IL
4 (from single-beam LER data)
+ cLH * IL * IH (from 2-beam, non-colliding ?)
+ BI (differential, trickle – coasting ?)
[+ BLT ] (LER only, vary VRF ?)
W. Kozanecki MDI & PEP-II BBR meetings, 5 May 06
Background characterization measurementsBackground characterization measurements
Step 1: Step 1: Beam-current scansBeam-current scans single-beam termssingle-beam terms
Data: Jan 04 (bef. therrmal outgassing crisis)
W. Kozanecki MDI & PEP-II BBR meetings, 5 May 06
SVT occupancy (FL1 M01-)
EMC cluster multiplicity
Beam-beam term• present in all subdetectors• reproducibility!
Step 2: L & beam-beam termsStep 2: L & beam-beam terms
Total occupancy
- HER single beam
- LER single beam
Data: Jan 04
W. Kozanecki MDI & PEP-II BBR meetings, 5 May 06
Proposed operational procedure: general guidelinesProposed operational procedure: general guidelines
BaBar taking data!BaBar taking data!
Perturb as adiabatically as possiblePerturb 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 settingAt 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 runsPedestal runs no beam
Reproducibilty: if beam(s) lost, redo last settingReproducibilty: if beam(s) lost, redo last setting
W. Kozanecki MDI & PEP-II BBR meetings, 5 May 06
W. Kozanecki MDI & PEP-II BBR meetings, 5 May 06
Time requestTime request
2 components2 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 experienceFrom 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
W. Kozanecki MDI & PEP-II BBR meetings, 5 May 06
To be clarifiedTo be clarified
PrerequisitesPrerequisites 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 timeMinimize data-taking time diamond/diode settling time?
best trigger rmix to enhance background fraction ?
When (not) to trickle?When (not) to trickle?
Need volunteer(s) to analyze data - incl. CsI & BLM!Need volunteer(s) to analyze data - incl. CsI & BLM!
W. Kozanecki MDI & PEP-II BBR meetings, 5 May 06
Spare slidesSpare slides
W. Kozanecki MDI & PEP-II BBR meetings, 5 May 06
Proposed operational procedure: colliding beam measurementsProposed operational procedure: colliding beam measurements
Setup: save configs & orbits; check fbcks; change BBR L1 config.Setup: save configs & orbits; check fbcks; change BBR L1 config.
Keep IKeep ILL ~ constant, vary I ~ constant, vary IHH (> 0.25 A, 0.25 A steps) (> 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’)trickle LER + HER (~ 5’)
– coast LER + HER (~ 5’)coast LER + HER (~ 5’)
Keep IKeep IHH ~ constant, vary I ~ constant, vary ILL (> 0.30 A, 0.35 A steps) (> 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’)trickle LER + HER (~ 5’)
– coast LER + HER (~ 5’)coast LER + HER (~ 5’)
Pedestal run Pedestal run
W. Kozanecki MDI & PEP-II BBR meetings, 5 May 06
Proposed operational procedure: single-beam measurementsProposed operational procedure: single-beam measurements
Vary IVary IHH : 0.25-1.6 A, 0.25 A steps, no LEB : 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 IVary ILL : 0.3-2.7 A, 0.35 A steps, no HEB : 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)Reproducibility check on single beam scans (esp. pins) repeat middle & top points of previous two scans (HER, then LER)
Non-colliding scan (sparse)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 Pedestal run
W. Kozanecki MDI & PEP-II BBR meetings, 5 May 06
Total time estimates (Total time estimates (ONLYONLY data taking + BBR on-off): 690' data taking + BBR on-off): 690'
SetupSetup 15’ 15’
Collision scan @ fixed LER currentCollision scan @ fixed LER current 160’160’
o IL = 1600 mA, vary IH 7 x 10’
o IL = 2700 mA , vary IH 7 x 13’
Collision scan @ fixed HER currentCollision scan @ fixed HER current 190’190’
o IH = 1000 mA , vary IL 8 x 10’
o IH = 1600 mA , vary IL 8 x 13’
PedestalsPedestals 5’ 5’
HER single-beam scanHER single-beam scan 5 x 10’ + 2 x 13'5 x 10’ + 2 x 13' 80’ 80’
LER single-beam scanLER single-beam scan 6 x 10’ + 2 x 13'6 x 10’ + 2 x 13' 90’ 90’
Repeat middle & top points of single-beam scans (H, L)Repeat middle & top points of single-beam scans (H, L) 50’ 50’
Non-colliding scansNon-colliding scans 90’ 90’
o IH = 1350 mA , vary IL 5 x 10’
o IL = 2350 mA , vary IH 4 x 10’
PedestalsPedestals 5’ 5’
W. Kozanecki MDI & PEP-II BBR meetings, 5 May 06
Background sourcesBackground sources
Luminosity (radiative-Bhabha debris) – Luminosity (radiative-Bhabha debris) – major concern (DCH future)major concern (DCH future)
BP ~ dP * L (strictly linear with L)
Beam-beam tailsBeam-beam tails
from LER tails: BL, bb ~ bL,bb*IL + fL(L,H +/-)
from HER tails: BH, bb ~ bH,bb*IH + fH(L,H +/-)
Beam-gas (bremsstrahlung + Coulomb)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)
BBII: LER injection (trickle) background: LER injection (trickle) background
BBLTLT (exp. signature somewhat similar to bremsstrahlung) (exp. signature somewhat similar to bremsstrahlung)
W. Kozanecki MDI & PEP-II BBR meetings, 5 May 06
Proposed operational procedure: colliding beam measurements (1)Proposed operational procedure: colliding beam measurements (1)
2000 & 2002 procedure:2000 & 2002 procedure: