Search for a Low Energy Excess in MicroBooNE Nicol Foppiani - - - PowerPoint PPT Presentation

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Search for a Low Energy Excess in MicroBooNE Nicol Foppiani - - - PowerPoint PPT Presentation

Jan 14, 2023 309 likes •595 views

Search for a Low Energy Excess in MicroBooNE Nicol Foppiani - Harvard University On behalf of the MicroBooNE collaboration 54th Rencontres de Moriond EW - Young Scientist Forum March 20th, 2019 1 Neutrino anomalies and the L ow E nergy E

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Search for a Low Energy Excess in MicroBooNE

54th Rencontres de Moriond EW - Young Scientist Forum March 20th, 2019

Nicolò Foppiani - Harvard University On behalf of the MicroBooNE collaboration

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Neutrino anomalies and the Low Energy Excess

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Anomalies in Short Baseline Neutrino Oscillations ➔ Might hide sterile neutrinos -> new physics BSM

  • LSND: excess of EM-like events
  • Phys. Rev. D 64, 112007
  • MiniBooNE: similar EM-like excess
  • Phys. Rev. Lett. 121, 221801

○ Could not distinguish electrons from photons

  • MicroBooNE: LEE is the primary goal

○ Is there an excess? ○ Origin? Electron-like or photon-like?

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SLIDE 3

Neutrino anomalies and the Low Energy Excess

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Anomalies in Short Baseline Neutrino Oscillations ➔ Might hide sterile neutrinos -> new physics BSM

  • LSND: excess of EM-like events
  • Phys. Rev. D 64, 112007
  • MiniBooNE: similar EM-like excess
  • Phys. Rev. Lett. 121, 221801

○ Could not distinguish electrons from photons

  • MicroBooNE: LEE is the primary goal

○ Is there an excess? ○ Origin? Electron-like or photon-like? Precision measurements of Cross Sections in liquid argon ➔ Improve understanding of nuclear physics in neutrino interactions ➔ Preparation for DUNE

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Micro Booster Neutrino Experiment at Fermilab

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Two beamlines:

  • BNB: On axis, 480 m from the production point

○ For the main physics goals of MicroBooNE ○ The heart of the SBN programme, with SBND and Icarus

  • NuMI: Off Axis (dedicated to NO𝝃A, MINER𝝃A, MINOS)

○ Complementary physics and cross checks

NuMI BNB Icarus SBND MicroBooNE

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A typical event

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A typical event

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Color shows deposited charge

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A typical event

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Z-axis [m] (beam direction) x-axis [time] (drift axis) Color shows deposited charge

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A typical event

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Z-axis [m] (beam direction) x-axis [time] (drift axis) Tracks: protons, pions, muons Color shows deposited charge

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A typical event

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Color shows deposited charge Z-axis [m] (beam direction) x-axis [time] (drift axis) Electromagnetic shower: electron-like, attached to the main vertex

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A typical 𝝆0->𝛅𝛅 event

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A typical 𝝆0->𝛅𝛅 event

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Electromagnetic showers detached from the vertex, photon conversion length ~26 cm

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LEE analysis strategy

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LEE analysis strategy

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Electron-like search:

  • Shower attached to the vertex
  • dE/dx of one MIP particle at the

start of the shower

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SLIDE 14

LEE analysis strategy

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Electron-like search:

  • Shower attached to the vertex
  • dE/dx of one MIP particle at the

start of the shower Photon-like search:

  • Shower detached from the vertex
  • dE/dx of two MIP particles at the

start of the shower

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SLIDE 15

LEE analysis strategy

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Electron-like search:

  • Shower attached to the vertex
  • dE/dx of one MIP particle at the

start of the shower Photon-like search:

  • Shower detached from the vertex
  • dE/dx of two MIP particles at the

start of the shower

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SLIDE 16

LEE analysis strategy

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Some data ready to develop the analyses:

  • Open data: 4e19 POT BNB (~3.5%) and 2.4e20 POT NuMI (21%)
  • Total data: about 1.13e21 POT BNB and 1.6e21 POT NuMI so far

Electron-like search:

  • Shower attached to the vertex
  • dE/dx of one MIP particle at the

start of the shower Photon-like search:

  • Shower detached from the vertex
  • dE/dx of two MIP particles at the

start of the shower

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𝝃eCC topologies

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  • Only one electron: 𝝃eCC 0𝝆0p

○ hardest to distinguish from single photon production

  • Additional protons: 𝝃eCC 0𝝆Np

○ Easier because additional tracks determine vertex ○ It is the channel in which the LEE has been

  • bserved
  • Additional pions: 𝝃eCC M𝝆Np

○ Very complex events ○ Typically higher energies

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𝝃eCC topologies

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  • Only one electron: 𝝃eCC 0𝝆0p

○ hardest to distinguish from single photon production

  • Additional protons: 𝝃eCC 0𝝆Np

○ Easier because additional tracks determine vertex ○ It is the channel in which the LEE has been

  • bserved
  • Additional pions: 𝝃eCC M𝝆Np

○ Very complex events ○ Typically higher energies

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SLIDE 19

BNB 𝝃eCC 0𝛒Np analysis

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Light and charge: remove cosmic rays Topological and geometrical requirements Calorimetry: particle ID and energy measurement

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BNB 𝝃eCC 0𝛒Np analysis

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Cross check: two sidebands on 3.5% of the total BNB data Light and charge: remove cosmic rays Topological and geometrical requirements Calorimetry: particle ID and energy measurement NC𝝆0 enriched (photon enriched) sideband 𝛏𝝂CC enriched sideband

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NuMI 𝝃eCC 0𝛒Np analysis

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Cross check the BNB analysis using NuMI

  • As many 𝝃eCC interactions as expected

in the full BNB dataset

  • Perfect to validate the analysis
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NuMI 𝝃eCC 0𝛒Np analysis

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Cross check the BNB analysis using NuMI

  • As many 𝝃eCC interactions as expected

in the full BNB dataset

  • Perfect to validate the analysis

cos(𝜾) wrt NuMI beam direction:

  • Cosmic rays: flat distribution
  • Neutrinos: peak around 1
  • Data/Monte Carlo agreement gives us

confidence we can tune and cross check the LEE analysis

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Conclusions

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  • Exciting moment for MicroBooNE:

○ Collected a huge amount of data ○ Solid strategy and demonstration of the LEE analyses

  • First Cross section measurements submitted for PRL publication

○ CC𝛏𝝂 𝛒0: MICROBOONE-NOTE-1032-PUB ○ CC𝛏𝝂 inclusive: MICROBOONE-NOTE-1045-PUB

  • Strong demonstration of the LEE analysis strategies

○ Electron-like search BNB: MICROBOONE-NOTE-1038-PUB ○ Electron-like search NuMI: MICROBOONE-NOTE-1054-PUB ○ Photon-like search BNB: MICROBOONE-NOTE-1041-PUB

Stay tuned: new results coming soon!

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BACKUP

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A liquid argon TPC

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Two signals:

  • Scintillation light, mainly for trigger and event selection
  • TPC information: reconstruct the event, tracking and calorimetry
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Neutrino Interactions in MicroBooNE

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Production of a lepton: clear exp signature. Distinguish different flavours For the LEE search -> need to distinguish the two flavours, only Charged Current (CC) are of interest! Typical neutrino energy ~ 1 GeV ➔ In this energy range interactions with the nuclei are predominant Neutral current interactions Charged current interactions Only nucleus recoil, hard to detect. No information about the flavour

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MicroBooNE during the construction

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Electron/photon separation using dE/dx

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