Background characterization md plan
Download
1 / 16

Background characterization: MD plan - PowerPoint PPT Presentation


  • 70 Views
  • Uploaded on

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

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about ' Background characterization: MD plan' - shilah


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
Background characterization md plan
Background characterization: MD plan

W. Kozanecki

  • MD goals

  • Background sources & parametrization

  • Operational procedures

  • Open questions


Md goals
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)


Proposed baseline parametrization
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?)


Proposed baseline parametrization1
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 ?)


Background characterization measurements

Data: Jan 04 (bef. therrmal outgassing crisis)

Background characterization measurements

Step 1: Beam-current scans

 single-beam terms


Data: Jan 04 outgassing crisis)

  • 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)


Proposed operational procedure general guidelines
Proposed operational procedure: general guidelines outgassing crisis)

  • 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


  • Time request
    Time request outgassing crisis)

    • 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


    To be clarified
    To be clarified outgassing crisis)

    • 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!


    Spare slides
    Spare slides outgassing crisis)


    Proposed operational procedure colliding beam measurements
    Proposed operational procedure: colliding beam measurements outgassing crisis)

    • 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


    Proposed operational procedure single beam measurements
    Proposed operational procedure: single-beam measurements outgassing crisis)

    • 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


  • Total time estimates only data taking bbr on off 690
    Total time estimates ( outgassing crisis)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’


    Background sources
    Background sources outgassing crisis)

    • 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)



    ad