ICECUBE-GEN2: THE NEXT GENERATION NEUTRINO

OBSERVATORY IN ANTARCTICA

Lu Lu for IceCube Gen2

Collaboration

Chiba University

Wilkinson Microwave

Anisotropy ProbeROSAT

CMB pair-production

NEUTRINOS: A NEW ERA FOR ASTRONOMY

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Hubble

FermiHAWC

IceCube

Pierre Auger

Telescope Array

GW

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WHY DO WE NEED GEN2 (HIGH ENERGY EXTENSION)The big picture:

Identify the sources responsible for high energy neutrinos seen by IceCube.

Extend diffuse spectrum to higher energy → connection with UHECR?

Neutrino flavour ratio and its indication of the source properties

Observation of Glashow resonance and tau neutrino

Cosmogenic neutrinos

…

Also:

Hadronic interaction models, cosmic-ray composition, charm production, exotic searches, PeV photons, high PT muons, elasticity and cross-section measurements …

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SO WE NEED A LARGER VOLUME In-ice upgrade*:

• ~ 10,000 more optical sensors

• 5 – 10 km3 instrumented volume

• ~ 120 strings

Wish-list:

• sensors with directionality and more effective area

• smaller holes to reduce drilling cost

• a surface array to veto cosmic-ray background

Challenges:

• -45ºC, 10,000 psi, logistics

*this talk we only focus on high-energy array for in-ice upgrade4

Gen2 High-energy array

PINGU

(low-energy)

In-ice high-energy array | surface veto array | ARA

GEOMETRY OPTIMISATION

# Strings 120

DOMs / String 80

String Length 1.3 km

Not yet decided, various types

Example geometry: “sunflower” with different string spacing

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200 m 240 m 300 m

In-ice high-energy array | surface veto array | ARA

DESIGNS FOR IN-ICE SENSORS

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• More sparse string spacing → sensors need to have larger effective area (Cherenkov UV photons)

• Benefits veto, event reconstruction

• For > PeV neutrinos we should have PMTs looking up since down-going is favoured due to earth absorption

IceCube DOM mDOM D-Egg WOMLOM

35 cm 36 cm 30 cm 11 cm 13 cm

Time delay

Time delay

Why new

sensors?

Directional information

Helps with reco

Simulation

down PMT

Simulation

upper PMT

Ch

arg

e

Hypo Anti-hypo

Example

200 TeV in sunflower 240 m

Down-going cascade

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PHYSICS CASE I: POINT SOURCE SENSITIVITY

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New sensor?

Current IceCube limit:

Markarian 421, 122 Mpc

δ= +38.21°

Discovery potential

PHYSICS CASE II: HIDDEN FEATURES IN THE DIFFUSE NEUTRINO SPECTRUM?

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Is there a connection

to UHECR?

Lars Mohrmann, phd thesis

?

Contained cascades and through-going

muons: events per year breaking down by

energy assuming E-2.13 spectrum

GEN2 WILL TELL US HOW DOES THE SPECTRUM GO

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Flavour dependent cut-off is an ultimate test for the source models

PHYSICS CASE III: FLAVOUR RATIO

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Glashow resonance boosts 6.3 PeV ഥν𝑒

π− → µ− + νµ 0: 1: 0

µ− → 𝑒− + ഥν𝑒+ νµ 1: 2: 0

𝑝 + 𝑝 → 𝑛π∓,0 + 𝑝 + 𝑝

ν𝑒νµ

synchrotron loss time < decay time,

muon loses energy before decay

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Muon damped

0:1:0 → 4:7:7

Neutron decay

π decay 1:2:0 → 1:1:1FLAVOUR RATIO

energy and flavour

dependent cut-off

Potentially to add

τ identification

1:0:0

https://en.wikipedia.org/wiki/Ternary_plot

30 years of Gen2, contours show 68% and 90%

SURFACE UPGRADESurface (75 km2 veto array) :

Icetop

Scintillators

Cherenkov telescope

Gary Binder

Surviva

l pro

ba

bility

Neutrino energy [GeV]

> PeV

Cos(z

enith

)

In-ice high-energy array | surface veto array | ARA

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1

14

IceActAir-Cherenkov telescope

STUDYING HADRONIC INTERACTIONS

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Ralph Engel

Only in-ice can measure!

UHECR COSMOGENIC →

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P. Allison et al. (The ARA collaboration) Phys. Rev. D 93, 082003http://www.southpolestation.com/

1000 km3 volume

In-ice high-energy array | surface veto array | ARA

Auger - 9 yr x 3

ARA 37 – 3 yr

IceCube- 2 yr

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ROAD MAP

SUMMARY

• The high energy extension of IceCube, Gen2 is under design

• New sensor R&D are on-going and maturing

• Gen2 will provide a new and unique view of the high-energy Universe

• Sources, source properties and connections with UHECR are to be discovered

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+ KIT

G e n t o o

BACKUP

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https://arxiv.org/abs/1609.04981v1

backup