Pileup Systematic Studies in The Fermilab Muon g-2 Experiment - - PowerPoint PPT Presentation

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Pileup Systematic Studies in The Fermilab Muon g-2 Experiment - - PowerPoint PPT Presentation

Oct 04, 2023 367 likes •575 views

Pileup Systematic Studies in The Fermilab Muon g-2 Experiment Meghna Bhattacharya University of Mississippi New Perspectives June, 2019 (On behalf of the Muon g-2 Collaboration) Muon g-2 Experimental Hall at Fermilab 2 Measurement of Muon

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Pileup Systematic Studies in The Fermilab Muon g-2 Experiment

Meghna Bhattacharya University of Mississippi New Perspectives June, 2019 (On behalf of the Muon g-2 Collaboration)

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2

Muon g-2 Experimental Hall at Fermilab

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Measurement of

❖

Muon Cyclotron frequency : ❖ Muon spin precession frequency : ❖ Experimentally measured : ➢ Anomalous precession frequency: ➢ Magnetic field:

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(Ideally)

For more details: Jason Hempstead (Muon g-2 in 10 minutes)

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Extracting (Using Threshold Method)

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  • Highest-energy emitted preferentially along

muon spin (Energy Cut > 1.7 GeV)

  • Results in sinusoidally-oscillating arrival time of

these in calorimeters

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More precise this time!

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  • Increase the statistics by a factor of 21 and reduce systematics by a factor of ~ 3 w.r.t

BNL experiment

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Pileup events

Two (or more) decay positrons hit a calorimeter too close in space and time The overlapping pulses are treated as a single pulse of higher energy(pileup events) Pileup events distort the time (carries a different g-2 phase) and energy spectra

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Evidence of two or more overlapping events 2 Energy spectra from all detectors

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Pileup construction

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❖ Form doublets by looking in “shadow” windows for shadow pulses ❖ The energy of the doublet is ❖ The time of the doublets are approximated as ❖ Pileup spectrum = Doublets-Singlets

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Pileup construction

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Pileup energy spectrum = Doublets - Singlets Original Energy Positive pileup Negative Pileup

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Pileup Correction

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Energy (MeV)

Original Energy Pileup Spectrum Corrected Spectrum = Original Energy - Pileup

Ratio

Ratio = pileup spectrum / original energy

  • Ratio -> Consistent with 1 if constructed correctly
  • Higher order pileup contamination around 5 GeV
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Pileup Time Spectra

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Preliminary Results

Uncorrected Wiggle spectrum Pileup Spectrum

Preliminary Results

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Conclusion

  • Muon g-2 experiment has completed run 1 and we are currently analyzing the data
  • Pileup is one of the most important source of systematic uncertainties to the anomalous spin

precession frequency measurement

  • Next step is to evaluate the systematic uncertainty coming from the Pileup events and finally

estimate the error

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Backup

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Why 1.7 GeV

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SM Contributions

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QED correction: by far the largest one....well understood EW contribution: the uncertainty is much smaller than the hadronic sector Hadronic sector: The uncertainty is dominated by the hadronic contribution and challenges the Theory community

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Doubles and single energy spectra

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Doubles Trigger pulse Shadow Pulse

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Measurement of

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In E821 (0.54 ppm)

Get from CODATA [1]: (0.00026 ppb) (3.0 ppb)

(22 ppb)

[1]. P. J. Mohr, D. B. Newell and B. N. Taylor, Rev. Mod. Phys.88, no. 3, 035009 (2016), doi:10.1103/RevModPhys.88.035009 [arXiv:1507.07956 [physics.atom-ph]]

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More Precise this time!

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Pileup

40 ppb

More Statistics Better uniform magnetic field Much smaller systematic errors Increase the statistics by a factor of 21 and reduce systematics by a factor of ~ 3 w.r.t BNL experiment

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What is g?

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❖ A charged elementary particle with half-integer intrinsic spin has magnetic dipole moment aligned with its spin : ❖ According to Dirac's theory = 2 ❖ 1947: Schwinger showed...the lowest order radiative correction to the electron spin magnetic moment results in ,

Schwinger term describing 1st order electron self-interaction

= 2.00238(6) Agreed well with the experiments and that is how we build confidence in new physics model

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Pileup Time Spectra Construction

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Chart of Doublets

: number of pileup events

  • > 1.7 GeV (threshold )
  • For N1 : gain a count in the time spectrum
  • For N4 : lose a count, because both singlets were above threshold
  • N2 , N3 : no net change of counts (only one singlet > 1.7 GeV)

= 1.7 GeV

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Why measure ?

❖ Contributions to come from all sectors of the Standard Model ❖ Greater than between the BNL measurement and current theory prediction ❖ Sensitive to many new models

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Status Quo

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[1] KNT2018, arXiv:1802.02995v1 [hep-ph]

[1]

FNAL

Physics BSM? Hint of New Physics? (World average) discrepancy

0.54 ppm (BNL) 0.14 ppm (FNAL Goal)

(Theory Total)