! Veto use outer layer to veto atmospheric muons " # - PowerPoint PPT Presentation

ν eto: Atmospheric neutrino passing fractions and their uncertainties for large-scale neutrino telescopes Carlos Argüelles, Sergio Palomares-Ruiz, Austin Schneider, Logan Wille & Tianlu Yuan PANE Workshop Trieste, Italy • 29 May 2018

Veto-based searches Contained searches at high energies can ✘ ! Veto use outer layer to veto atmospheric muons " # ✓ High-energy, contained events in IceCube ! 2

Atmospheric neutrino passing frac2ons Atmospheric neutrinos from the southern sky may be vetoed if accompanied by high-energy muon Veto probability correlated with energy and ✘ direc9on of neutrino Needed to understand how atmospheric neutrinos make it into our sample Proposed by SGRS [PRD 79, 043009 (2009)] Extended by GJKvS [PRD 90, 023009 (2014)] 3

Zenith dependence J. van Santen, ICRC2017 Passing fraction : probability of an atmospheric neutrino to not be vetoed self-veto effect -.// (1 , ,2 3 ) + , ! "#$$ % & , ( ) = • prompt + , (1 , ,2 3 ) conv. 5 6 Alters the zenith distribution of atmospheric neutrinos in the southern sky conv. 5 7 Southern sky Northern sky 4

HESE 6-year zenith distribution " Zenith distribu-on in southern-sky N. Wandkowsky, TeVPA 2017 incompa2ble with background But this background suppression is calculated en2rely using the passing frac-on Assuming isotropic prompt, passing frac2on breaks degeneracy between prompt and diffuse astrophysical flux Drives current bound on prompt 5

Start of this saga CA, SPR, and TY met at VietNus workshop on systematics for neutrino experiments Prompt ! " + ̅ ! " Conventional ! " + ̅ ! " Lines: GJKvS Crosses: CORSIKA MC Quy Nhon, Vietnam Discrepancies in passing fraction calculation vs CORSIKA w/ SIBYLL 2.3 Unclear how to take systematic uncertainties into account at the time Idea: Use MCEq and calculate directly! 6

Muon range Veto is triggered by muons à Ask how likely an atmospheric muon is to reach the detector High-energy muon At high energies, muon is no longer minimum ionizing Stochastic energy losses become important 7

Muon range pdfs * |( ) * , as a , , .ice) , the pdf of the muon energy at depth, ( ) Need to evaluate ! "#$%& (( ) , at surface and .ice the overburden function of ( ) , ( ) .ice * ( ) , = ( ) , , .ice) Various .ice * |( ) 3(( ) * [GeV] ( ) 8

Detec%on probability Simulate muons using MMC [arXiv:hep-ph/0407075] and build pdfs * ) , to get detecDon probability Convolute with detector response, ! "#$%& (( ) , - = Zenith angle, detector coordinates 9

Detection probability Previously, median muon range assumed [SGRS, PRD 79, 043009 (2009)] %&'% = Θ(+ , -#"./0 − + , ) • ! "#$ 0 = %&'% "#$ ! 1 = % ' & % $ # ! " 5 6 = Zenith angle, detector coordinates 10

GJKvS, PRD 90, 023009 (2014) Uncorrelated muons Atmospheric electron neutrinos may coincide with muons from other branches in shower Expected number of muons from DetecKon proto. shower to probability trigger veto Muon yield from Assuming median muon-range prototypical shower %&'% = Θ(+ , -#"./0 − + , ) ! "#$ Poisson probability of Neutrino yield from detecting 0 muons prototypical shower from proto. shower 11

SGRS, PRD 79, 043009 (2009) Correlated muons Atmospheric muon neutrinos always have a sibling muon in addition to other branches Muon decay spectrum; condiJonal on ! " , ! # Assuming 2-body $% ",' ( ) ( = *(! " − ! # + ! ' $! ' Parent flux at Neutrino yield X from proto. from parent p shower 12

Previous calculations Single set of assumptions for primary flux, hadronic model, atmosphere density and muon range • Correlated passing fraction analytically calculated • Uncorrelated passing fraction obtained from fit to CORSIKA • Equations were not formulated in the notation of previous slides At low ! " , partner muon energy is too low to reach detector At higher ! " , partner muon energy increases and is more likely to trigger veto 13

This work [arxiv:1805.11003] Unified treatment Muon-range from MMC n-body decays from Pythia 8.1 Fluxes and yields from MCEq [Fedynitch, [CPC 178, 852-867] [arXiv:hep-ph/0407075] hNps://github.com/afedynitch/MCEq] Coupling via ! " subtracQon Correlated, Uncorrelated, proto. shower sibling muon muons; Poisson 14

Unified passing fractions Prompt ν e Conventional ν e Default settings 1 . 0 1 . 0 • H3a primary flux SIBYLL 2.3c hadronic model • 0 . 8 0 . 8 GJKvS uncorrelated, MSIS-90-E SP/July atmosphere • density Passing fraction conven0onal calculaUons Passing fraction 0 . 6 0 . 6 ALLM97 muon-range model • from fits to CORSIKA with • 1.95 km depth in ice SIBYLL 2.1 0 . 4 0 . 4 1 TeV detection threshold • cos θ z = 0 . 25 cos θ z = 0 . 25 0 . 2 0 . 2 cos θ z = 0 . 85 cos θ z = 0 . 85 This work This work GJKvS GJKvS 0 . 0 0 . 0 10 3 10 4 10 5 10 6 10 7 10 3 10 4 10 5 10 6 10 7 Conventional ν µ Prompt ν µ E ν [GeV] E ν [GeV] 1 . 0 1 . 0 cos θ z = 0 . 25 cos θ z = 0 . 25 cos θ z = 0 . 85 cos θ z = 0 . 85 This work This work 0 . 8 0 . 8 GJKvS GJKvS GJKvS uncorrelated, prompt Passing fraction Passing fraction GJKvS correlated 0 . 6 0 . 6 calculations from fits to calculaUon taken from CORSIKA with DPMJET-2.55 0 . 4 SGRS analyUc formula 0 . 4 0 . 2 0 . 2 Shoulder disappears (solid) due to muon stochasUcs 0 . 0 0 . 0 10 3 10 4 10 5 10 6 10 7 10 3 10 4 10 5 10 6 10 7 15 E ν [GeV] E ν [GeV]

Verifica(on against CORSIKA w. SIBYLL 2.3 CORSIKA set generated with Conventional ν µ / ¯ ν µ H3a primary flux • 1 . 0 cos θ z = 0 . 25 SIBYLL 2.3 hadronic model • cos θ z = 0 . 45 MSIS-90-E SP/July • cos θ z = 0 . 85 atmosphere density 0 . 8 CORSIKA ν µ CORSIKA ¯ ν µ • 1.95 km depth in ice neutrino Passing Fraction • 1 TeV detection threshold antineutrino 0 . 6 Excellent agreement for both neutrino and antineutrino 0 . 4 No fitting performed! 0 . 2 ν eto obviates need for high- statistics CORSIKA! 0 . 0 10 4 10 5 10 6 10 7 10 3 E ν [GeV] 16

Verification against CORSIKA w. SIBYLL 2.3 CORSIKA set generated with Conventional ν e / ¯ Prompt ν e / ¯ ν e ν e 1 . 0 1 . 0 • H3a primary flux SIBYLL 2.3 hadronic model • 0 . 8 0 . 8 MSIS-90-E SP/July atmosphere • Passing Fraction density Passing Fraction 0 . 6 0 . 6 1.95 km depth in ice • • 1 TeV detection threshold cos θ z = 0 . 25 cos θ z = 0 . 25 0 . 4 0 . 4 cos θ z = 0 . 45 cos θ z = 0 . 45 cos θ z = 0 . 85 cos θ z = 0 . 85 CORSIKA ν e CORSIKA ν e 0 . 2 0 . 2 CORSIKA ¯ ν e CORSIKA ¯ ν e neutrino neutrino antineutrino antineutrino 0 . 0 0 . 0 10 3 10 4 10 5 10 6 10 7 10 3 10 4 10 5 10 6 10 7 Conventional ν µ / ¯ Prompt ν µ / ¯ ν µ ν µ E ν [GeV] E ν [GeV] 1 . 0 1 . 0 cos θ z = 0 . 25 cos θ z = 0 . 25 cos θ z = 0 . 45 cos θ z = 0 . 45 cos θ z = 0 . 85 cos θ z = 0 . 85 0 . 8 0 . 8 CORSIKA ν µ CORSIKA ν µ CORSIKA ¯ ν µ CORSIKA ¯ ν µ Passing Fraction neutrino Passing Fraction neutrino antineutrino antineutrino 0 . 6 0 . 6 0 . 4 0 . 4 0 . 2 0 . 2 0 . 0 0 . 0 10 3 10 4 10 5 10 6 10 7 10 3 10 4 10 5 10 6 10 7 17 E ν [GeV] E ν [GeV]

Effect of ! " subtrac.on Default se,ngs • H3a primary flux Conventional ν e SIBYLL 2.3c hadronic model • 1 . 0 MSIS-90-E SP/July atmosphere • density ALLM97 muon-range model • • 1.95 km depth in ice 0 . 8 1 TeV detecQon threshold • Passing Fraction Subtract parent energy from primary 0 . 6 CR to calculate distribuQons for prototypical showers 0 . 4 cos θ z = 0 . 25 Affects higher energies; not enough cos θ z = 0 . 45 CORSIKA staQsQc cos θ z = 0 . 85 0 . 2 CORSIKA Full Approximate 0 . 0 10 3 10 4 10 5 10 6 10 7 E ν [GeV] 18

Importance of muon-range Default settings • H3a primary flux Conventional ν e SIBYLL 2.3c hadronic model • 1 . 0 MSIS-90-E SP/July atmosphere • density ALLM97 muon-range model • • 1.95 km depth in ice 0 . 8 1 TeV detection threshold • Passing Fraction 0 . 6 0 . 4 cos θ z = 0 . 25 Using the average muon- cos θ z = 0 . 45 range treatment (dashed) cos θ z = 0 . 85 0 . 2 results in large discrepancies Muon Range Dist. with CORSIKA Average Treatment 0 . 0 10 3 10 4 10 5 10 6 10 7 E ν [GeV] 19

Importance of muon-range Default se8ngs • H3a primary flux Conventional ν µ SIBYLL 2.3c hadronic model • 1 . 0 MSIS-90-E SP/July atmosphere • density cos θ z = 0 . 25 ALLM97 muon-range model • cos θ z = 0 . 45 Correlated Passing Fraction • 1.95 km depth in ice 0 . 8 cos θ z = 0 . 85 1 TeV detec-on threshold • Muon Range Dist. Average Treatment 0 . 6 0 . 4 For muon neutrinos , stochas-c losses smears out passing 0 . 2 frac-on 0 . 0 10 3 10 4 10 5 10 6 10 7 E ν [GeV] 20