Background characterization: MD plan

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


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)


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?)


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 ?)


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)


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


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


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


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!


Spare slidesSpare slides


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


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


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’


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)


Proposed operational procedure: colliding beam measurements (1)Proposed operational procedure: colliding beam measurements (1)

2000 & 2002 procedure:2000 & 2002 procedure:

Background characterization: MD plan

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