Study of neutrino oscillations with ANTARES
description
Transcript of Study of neutrino oscillations with ANTARES
![Page 1: Study of neutrino oscillations with ANTARES](https://reader038.fdocument.pub/reader038/viewer/2022102909/568139cc550346895da17c57/html5/thumbnails/1.jpg)
Study of neutrino Study of neutrino oscillations with oscillations with
ANTARESANTARES
J. BrunnerJ. Brunner
![Page 2: Study of neutrino oscillations with ANTARES](https://reader038.fdocument.pub/reader038/viewer/2022102909/568139cc550346895da17c57/html5/thumbnails/2.jpg)
Method : Use event ratiosMethod : Use event ratios
MC events with oscillations
Split intoNon-oscillation event rate
Oscillation correction
Rate of observed events in 2 channelsCan be expressed in these terms
Analytical calculation of mixing angle for eachΔm2, error propagation (stat&syst) from R
Many systematic effects cancel or attenuate for R 22
![Page 3: Study of neutrino oscillations with ANTARES](https://reader038.fdocument.pub/reader038/viewer/2022102909/568139cc550346895da17c57/html5/thumbnails/3.jpg)
Choose two appropriate Choose two appropriate channelschannels
• Single line eventsSingle line events lower energy and more vertical lower energy and more vertical
• Multi-line eventsMulti-line events higher energy & more isotropic higher energy & more isotropic
• Strong effect of oscillations for single line events Strong effect of oscillations for single line events – marginal for multiline events– marginal for multiline events
Elevation Neutrino Energy
2322 104.2;12sin eVm
![Page 4: Study of neutrino oscillations with ANTARES](https://reader038.fdocument.pub/reader038/viewer/2022102909/568139cc550346895da17c57/html5/thumbnails/4.jpg)
E/L : differences enhancedE/L : differences enhanced
• R1 = 0.82 (with osc/no osc)R1 = 0.82 (with osc/no osc)• R3 = 0.97 (with osc/no osc)R3 = 0.97 (with osc/no osc)• Fit mixing angle (linear) for each Fit mixing angle (linear) for each ΔΔmm22 for ratio R1/R3 for ratio R1/R3• In practice : R3 supplies flux normalizationIn practice : R3 supplies flux normalization
2322 104.2;12sin eVm
![Page 5: Study of neutrino oscillations with ANTARES](https://reader038.fdocument.pub/reader038/viewer/2022102909/568139cc550346895da17c57/html5/thumbnails/5.jpg)
Track reconstructionTrack reconstruction
• Good efficiency down to low energies Good efficiency down to low energies – 20 GeV = 100m muon track for oscillation 20 GeV = 100m muon track for oscillation
analysisanalysis
• Good rejection of downgoing muonsGood rejection of downgoing muons
• Reliable zenith angle resolution Reliable zenith angle resolution – few degreesfew degrees
• Azimuth determination / pointing accuracyAzimuth determination / pointing accuracy– not needednot needed
![Page 6: Study of neutrino oscillations with ANTARES](https://reader038.fdocument.pub/reader038/viewer/2022102909/568139cc550346895da17c57/html5/thumbnails/6.jpg)
Reconstruction conceptReconstruction concept
![Page 7: Study of neutrino oscillations with ANTARES](https://reader038.fdocument.pub/reader038/viewer/2022102909/568139cc550346895da17c57/html5/thumbnails/7.jpg)
1.1. Select “hot spots” at each detector Select “hot spots” at each detector string string should correspond to point of closest should correspond to point of closest approach of muon track and detector approach of muon track and detector lineline
![Page 8: Study of neutrino oscillations with ANTARES](https://reader038.fdocument.pub/reader038/viewer/2022102909/568139cc550346895da17c57/html5/thumbnails/8.jpg)
2. Add hits from neighboring floors in narrow 2. Add hits from neighboring floors in narrow time windowtime window
![Page 9: Study of neutrino oscillations with ANTARES](https://reader038.fdocument.pub/reader038/viewer/2022102909/568139cc550346895da17c57/html5/thumbnails/9.jpg)
3. Perform minimization of time/distance/amplitude 3. Perform minimization of time/distance/amplitude related function with all selected hit using a related function with all selected hit using a simplified geometry simplified geometry obtain track parameters obtain track parameters
![Page 10: Study of neutrino oscillations with ANTARES](https://reader038.fdocument.pub/reader038/viewer/2022102909/568139cc550346895da17c57/html5/thumbnails/10.jpg)
Recent clean lowE single-line Recent clean lowE single-line eventeventClose to vertical
Good fit
No correlated activity in any other line
1010
![Page 11: Study of neutrino oscillations with ANTARES](https://reader038.fdocument.pub/reader038/viewer/2022102909/568139cc550346895da17c57/html5/thumbnails/11.jpg)
Recent clean lowE single-line Recent clean lowE single-line eventevent
Point of closest approachCannot be atm muon
7 storeys hit8 storeys high100m = 20 GeVTotal signal: 17 p.e.
1111
![Page 12: Study of neutrino oscillations with ANTARES](https://reader038.fdocument.pub/reader038/viewer/2022102909/568139cc550346895da17c57/html5/thumbnails/12.jpg)
Data sampleData sample• 4 years of ANTARES data taking 2007-20104 years of ANTARES data taking 2007-2010
• 2007 : 5 lines active2007 : 5 lines active
• 2008-2010 : 10,11,12 lines active2008-2010 : 10,11,12 lines active
• Use Physics runs which fulfill basic quality Use Physics runs which fulfill basic quality criteriacriteria
• Total active time : 830 daysTotal active time : 830 days
1212
![Page 13: Study of neutrino oscillations with ANTARES](https://reader038.fdocument.pub/reader038/viewer/2022102909/568139cc550346895da17c57/html5/thumbnails/13.jpg)
Multi-line event selectionMulti-line event selection
• Cuts are chosen for extremely high purity against atm Cuts are chosen for extremely high purity against atm contributioncontribution
• Final cuts Final cuts Fit Quality<1.3Fit Quality<1.3 && && sinsinθθ<-0.15<-0.15 (8.6 (8.6ºº below horizon) below horizon)
• Vary MC input: water parameters & angular DOM acceptanceVary MC input: water parameters & angular DOM acceptance
• Data/(Data/(++)MC between )MC between 0.970.97 to to 0.8150.815– compatible with flux uncertainty and total detector acceptance compatible with flux uncertainty and total detector acceptance
tolerancetolerance
• Numbers are for 2008 only hereNumbers are for 2008 only here
data 491 MC 504 603 MC 1.2 3.5
cut
sinθ<-0.15 tchi2<1.3
cut 1414
![Page 14: Study of neutrino oscillations with ANTARES](https://reader038.fdocument.pub/reader038/viewer/2022102909/568139cc550346895da17c57/html5/thumbnails/14.jpg)
Multi-Line Events for Full data Multi-Line Events for Full data setset
• 1518 1518 Event candidates in totalEvent candidates in total
• Neutrino Oscillation: reduce sample by Neutrino Oscillation: reduce sample by 3.3%3.3%
• Muon impurity Muon impurity ~1%~1%
• MC MC 14% 14% high for all years within high for all years within statistical fluctuationsstatistical fluctuations
• Reminder: Absolute normalisation cancels in Reminder: Absolute normalisation cancels in event ratioevent ratio
• Following plots: MC scaled by 0.857 Following plots: MC scaled by 0.857
1515
![Page 15: Study of neutrino oscillations with ANTARES](https://reader038.fdocument.pub/reader038/viewer/2022102909/568139cc550346895da17c57/html5/thumbnails/15.jpg)
Year by YearYear by YearNumber of Used StoreysNumber of Used Storeys
1818
![Page 16: Study of neutrino oscillations with ANTARES](https://reader038.fdocument.pub/reader038/viewer/2022102909/568139cc550346895da17c57/html5/thumbnails/16.jpg)
Single Line Event SelectionSingle Line Event Selection2007-20102007-2010
• Nstorey>7 : hard cut to suppress muonsNstorey>7 : hard cut to suppress muons
• tchi2<0.95tchi2<0.95
• tcosth > 0 (upward going) tcosth > 0 (upward going)
1919
![Page 17: Study of neutrino oscillations with ANTARES](https://reader038.fdocument.pub/reader038/viewer/2022102909/568139cc550346895da17c57/html5/thumbnails/17.jpg)
Single Line Event SelectionSingle Line Event Selection2007-20102007-2010
• Nstorey>7 : hard cut to suppress muonsNstorey>7 : hard cut to suppress muons
• tchi2<0.95tchi2<0.95
• tcosth > 0 (upward going) tcosth > 0 (upward going)
2020
![Page 18: Study of neutrino oscillations with ANTARES](https://reader038.fdocument.pub/reader038/viewer/2022102909/568139cc550346895da17c57/html5/thumbnails/18.jpg)
Single-Line MCSingle-Line MCYear by YearYear by Year
• Muon impurity ~5%Muon impurity ~5%
• Neutrino oscillationsNeutrino oscillations– 18% reduction 18% reduction – Suppression of ~90 eventsSuppression of ~90 events– Corresponds to ~4-sigma effect w.r.t. Corresponds to ~4-sigma effect w.r.t.
statistical error (23 events)statistical error (23 events)
2121
![Page 19: Study of neutrino oscillations with ANTARES](https://reader038.fdocument.pub/reader038/viewer/2022102909/568139cc550346895da17c57/html5/thumbnails/19.jpg)
Systematic error & Systematic error & Selection StabilitySelection Stability
• MethodMethod– Use both “Test” MC & “average” MCUse both “Test” MC & “average” MC
•MCMC11 : “low count” MC : “low count” MC
•MCMC2 2 : “high count” MC: “high count” MC
•MCMCmm : “average” MC with MC : “average” MC with MCmm = (MC = (MC11 + MC + MC22)/2)/2
– Consider Multi-Line and Single-Line SelectionConsider Multi-Line and Single-Line Selection– Vary Fit quality cut around chosen valueVary Fit quality cut around chosen value
– Evaluate ratios X = MCEvaluate ratios X = MC11 / MC / MCmm for various cuts for various cuts
– Evaluate double ratios XEvaluate double ratios XML ML / X/ X1L1L
– Systematic error from variations of XSystematic error from variations of XML ML / X/ X1L1L
2323
![Page 20: Study of neutrino oscillations with ANTARES](https://reader038.fdocument.pub/reader038/viewer/2022102909/568139cc550346895da17c57/html5/thumbnails/20.jpg)
Systematic errorSystematic errorSingle Line Sample
Multi Line Sample
Fit quality cut varied
Fit quality cut varied
2424
![Page 21: Study of neutrino oscillations with ANTARES](https://reader038.fdocument.pub/reader038/viewer/2022102909/568139cc550346895da17c57/html5/thumbnails/21.jpg)
Systematic errorSystematic errorSingle Line Sample
Multi Line Sample
Simulated Muon Rates
Simulated Muon Rates
2525
![Page 22: Study of neutrino oscillations with ANTARES](https://reader038.fdocument.pub/reader038/viewer/2022102909/568139cc550346895da17c57/html5/thumbnails/22.jpg)
Systematic errorSystematic errorSingle Line Sample
Multi Line Sample
Simulated Neutrino Rates
Simulated Neutrino Rates
2626
![Page 23: Study of neutrino oscillations with ANTARES](https://reader038.fdocument.pub/reader038/viewer/2022102909/568139cc550346895da17c57/html5/thumbnails/23.jpg)
Systematic errorSystematic errorSingle Line Sample
Multi Line SampleVariation w.r.t. average MC
18% between MC1 & MC2
9% variation to MCm
Very stable against cut variations
Very stable between single-line and multi-line sample
cancellation of systematics in R confirmed !
2727
![Page 24: Study of neutrino oscillations with ANTARES](https://reader038.fdocument.pub/reader038/viewer/2022102909/568139cc550346895da17c57/html5/thumbnails/24.jpg)
Systematic errorSystematic error
• Consider all 25 Consider all 25 combinations of single-combinations of single-line and multi-line cutsline and multi-line cuts
• Plot double ratio Plot double ratio – XXML ML / X/ X1L1L
• Distribution well Distribution well centered around 1centered around 1
• Spread totally contained Spread totally contained within 3%within 3%
• Propose 3% as Propose 3% as conservative syst. errorconservative syst. error
Ratio of Ratios25 entriesXML / X1L
2828
![Page 25: Study of neutrino oscillations with ANTARES](https://reader038.fdocument.pub/reader038/viewer/2022102909/568139cc550346895da17c57/html5/thumbnails/25.jpg)
ResultsResults
• Assuming “standard” Assuming “standard” oscillations, coherent oscillations, coherent data/MC ratio of 0.86data/MC ratio of 0.86
• Larger year-by-year Larger year-by-year fluctuations for 1L fluctuations for 1L due to smaller due to smaller statisticsstatistics
• Ok within statistical Ok within statistical errorerror
Single-line events
Multi-line events
2929
Data R = 472/1518 = 0.311+/-0.019 (stat&syst)MC Non-Osc: R = 636/1837 = 0.346Non-oscillation hypothesis at 1.8 sigma from measured ratio
![Page 26: Study of neutrino oscillations with ANTARES](https://reader038.fdocument.pub/reader038/viewer/2022102909/568139cc550346895da17c57/html5/thumbnails/26.jpg)
ResultsResults
• Assuming “standard” Assuming “standard” oscillations, coherent oscillations, coherent data/MC ratio of 0.86data/MC ratio of 0.86
• Larger year-by-year Larger year-by-year fluctuations for 1L fluctuations for 1L due to smaller due to smaller statisticsstatistics
• Ok within statistical Ok within statistical errorerror
Single-line events
Multi-line events
3030
Data R = 472/1518 = 0.311+/-0.019 (stat&syst)MC Non-Osc: R = 636/1837 = 0.346Non-oscillation hypothesis at 1.8 sigma from measured ratio PRELIMINARY
![Page 27: Study of neutrino oscillations with ANTARES](https://reader038.fdocument.pub/reader038/viewer/2022102909/568139cc550346895da17c57/html5/thumbnails/27.jpg)
Example result from MCExample result from MC• Active time 2007-2010 : 830 days (220 days with 5 lines Active time 2007-2010 : 830 days (220 days with 5 lines
only)only)
• Assumed true values: Assumed true values: ΔΔmm22=2.4 10=2.4 10-3-3 eV eV22 & max. mixing & max. mixing
• Reachable 1-sigma precision in Reachable 1-sigma precision in ΔΔmm22 for maximal mixing 33% for maximal mixing 33%
Best fit1 sigma90% C.L.
1 sigma
N1/N2 : 5.7% Δm2 : 33%
![Page 28: Study of neutrino oscillations with ANTARES](https://reader038.fdocument.pub/reader038/viewer/2022102909/568139cc550346895da17c57/html5/thumbnails/28.jpg)
ResultResult
• 1-sigma in 1-sigma in ΔΔmm22 for maximal mixing: for maximal mixing: 1.4-3.0 101.4-3.0 10-3-3 eV eV22
• ΔΔmm22=2.2 +/- 0.8 10=2.2 +/- 0.8 10-3-3 eV eV22
• Active time 2007-2010 : 830 days (220 days with 5 lines Active time 2007-2010 : 830 days (220 days with 5 lines only)only)
• Non-oscillations excluded at 1.8 sigmaNon-oscillations excluded at 1.8 sigma
N1/N2 : 6.1% Δm2 : 36%
3232
![Page 29: Study of neutrino oscillations with ANTARES](https://reader038.fdocument.pub/reader038/viewer/2022102909/568139cc550346895da17c57/html5/thumbnails/29.jpg)
ResultResult
• 1-sigma in 1-sigma in ΔΔmm22 for maximal mixing: for maximal mixing: 1.4-3.0 101.4-3.0 10-3-3 eV eV22
• ΔΔmm22=2.2 +/- 0.8 10=2.2 +/- 0.8 10-3-3 eV eV22
• Active time 2007-2010 : 830 days (220 days with 5 lines Active time 2007-2010 : 830 days (220 days with 5 lines only)only)
• Non-oscillations excluded at 1.8 sigmaNon-oscillations excluded at 1.8 sigma
N1/N2 : 6.1% Δm2 : 36%
3333
PRELIMINARY
![Page 30: Study of neutrino oscillations with ANTARES](https://reader038.fdocument.pub/reader038/viewer/2022102909/568139cc550346895da17c57/html5/thumbnails/30.jpg)
Next stepsNext steps• Go from event ratio to fit of E/L Go from event ratio to fit of E/L
distributiondistribution
• Even better: 2-dim grid in E versus LEven better: 2-dim grid in E versus L
• Further cleaning of low Energy sample Further cleaning of low Energy sample from atmospheric muons neededfrom atmospheric muons needed
15 30 45 GeV
Differential Effect of oscillations well visibleFind magic cut to get rid of this
![Page 31: Study of neutrino oscillations with ANTARES](https://reader038.fdocument.pub/reader038/viewer/2022102909/568139cc550346895da17c57/html5/thumbnails/31.jpg)
BackupBackup
![Page 32: Study of neutrino oscillations with ANTARES](https://reader038.fdocument.pub/reader038/viewer/2022102909/568139cc550346895da17c57/html5/thumbnails/32.jpg)
Tau Neutrino appearance ? Tau Neutrino appearance ?
• Cascade-like events effectively Cascade-like events effectively suppressedsuppressed
• 17% branching ratio into muons17% branching ratio into muons
• Nutau CC cross section much lowerNutau CC cross section much lower
• Negligible effect for present analysisNegligible effect for present analysis