Deepak Tiwari for the INO Collaboration XIX International

Deepak Tiwari for the INO Collaboration

XIX International Workshop on Neutrino Telescopes 18-26 February 2021 India-based Neutrino Observatory

26 February 2021 | Deepak Tiwari | XIX International Workshop on Neutrino Telescopes | 1 The ICAL@INO

ICAL (Iron CALorimeter) is a proposed 50kt magnetized iron detector with glass Resistive Plate Chambers (RPCs) as the active detectors.

ICAL at a glance No. of modules 3 Module dimension 16 m × 16 m × 14.5 m Detector dimension 48 m × 16 m × 14.5 m No. of layers 151 Iron plate thickness 5.6 cm Gap for RPC trays 4.0 cm Magnetic ﬁeld 1.5 Tesla RPC RPC unit dimension 1.84 m × 1.84 m × 2.5 cm Readout strip width 3 cm No. of RPC units/layers/module 64 Total no. of RPC units 2 30,000 No. of electronic readout channels 3.9 × 106

26 February 2021 | Deepak Tiwari | XIX International Workshop on Neutrino Telescopes | 2 INO Goals

26 February 2021 | Deepak Tiwari | XIX International Workshop on Neutrino Telescopes | 3 INO: A long journey

I Circa 2000: An idea for a large underground neutrino detector conceived. I 2002: An MoU between 6 Department of Atomic Energy (DAE) Institutions signed. I 2006: INO Report submitted to the Chairman DAE. I 2010 : Detailed Project Report (DPR) on INO Site by Tamil Nadu (TN) Electricity Board, environmental clearance for Pottipuram Site. I 2015 : Financial approval for the full project came in January. I Present: Awaiting clearances from National Board of Wildlife, Madurai Town Planning, authority for Civil construction at the Site, and ﬁnally TN Pollution Control Board. Major hurdles: I An unfortunate beginnings of misinformed campaign since September 2012. I Legal hurdles since 2015, delays due to various other, non-scientiﬁc, considerations.

26 February 2021 | Deepak Tiwari | XIX International Workshop on Neutrino Telescopes | 4 INO: Present status

I Forest & Environment clearance obtained and Civil DPR report completed. Geotechnical studies completed. I Land for surface facilities and for the Inter-Institutional Centre for HEP (IICHEP), Madurai procured. I IICHEP will be the nodal centre for all activities, and will operate and maintain the INO laboratory and as a center for detector R&D for HEP, NP, Astrophysics in general.

I Strong outreach efforts are underway to counter misinformation spread by NGOs, politicians, some sections of media and press. I Overwhelming support for INO from the International Neutrino Community.

26 February 2021 | Deepak Tiwari | XIX International Workshop on Neutrino Telescopes | 5 INO: status & way ahead

I ICAL detector R&D complete – DPR for detector, DAQ systems ready, gas system design ﬁnalized. I Ready for Industrial production of all components of the detector. I Plan to have Cosmic Muon Veto Detector (CMVD) for mini-ICAL using extruded Plastic Scintillator. I Construction of Engineering module (eICAL) (700 ton) at the IICHEP in Madurai to test all aspects of ICAL and logistics of operation. to be built in next 2.5 years, all the requisite clearances obtained from the 85 ton magnetized mini-ICAL (4m × 4m × state government. 11 layers) commissioned in May 2018 at the I R&D going on to explore the possibilities of transit campus of IICHEP, Madurai a shallow depth (30-100 m) detector.

26 February 2021 | Deepak Tiwari | XIX International Workshop on Neutrino Telescopes | 6 ICAL response to muons

1 0.8 0.98

0.6 0.96 rec CID ε

cos θ = 0.35 ε cos θ = 0.35 cos θ = 0.45 cos θ = 0.45 0.4 cos θ = 0.55 0.94 cos θ = 0.55 cos θ = 0.65 cos θ = 0.65 cos θ = 0.75 cos θ = 0.75 0.2 cos θ = 0.85 0.92 cos θ = 0.85 20 40 60 80 100 20 40 60 80 100

Eµ(GeV) Eµ(GeV)

0.05 cos θ = 0.35 0.25 cos θ = 0.45 0.04 cos θ = 0.55 cos θ = 0.65 θ cos θ = 0.75

E 0.2 0.03 cos θ = 0.85 cos σ cos θ = 0.35 cos θ = 0.45 σ 0.15 cos θ = 0.55 0.02 cos θ = 0.65 cos θ = 0.75 0.01 0.1 cos θ = 0.85 20 40 60 80 100 20 40 60 80 100

Eµ(GeV) Eµ(GeV) Tiwari et al, JCAP 1805 (2018) no.05, 006

26 February 2021 | Deepak Tiwari | XIX International Workshop on Neutrino Telescopes | 7 Indirect searches with neutrinos as a probe

I At regions of high WIMP concentration, annihilation can give rise to neutrino-anti neutrino ﬂuxes as their ﬁnal product. I The atmospheric neutrinos pose a severe background to the signal neutrinos due to WIMP annihilation.

I The fact that signal and background neutrinos differ in their energy and angular distribution can be used for background suppression. Image source : https://fermi.gsfc.nasa.gov/science/eteu/dm/ Image source : arXiv:1111.0507

26 February 2021 | Deepak Tiwari | XIX International Workshop on Neutrino Telescopes | 8 The simulation & analysis framework

WIMPSIM/PPPC4DMID Honda ﬂuxes

norm. & osc. parameters Normalisation Event generation ICAL geom. and Oscillation with GENIE

Event generation Re-weighting Osc. parameters with GENIE signal µ folding µ response with Geant4 Incorporating De- Angular suppres- Solar/GC exposure prob. tector response bkg µ sion of background recon. events

χ2 analysis Cone optimisation

σ v sensitivity limits h A i

THEORY = Atmospheric + DM ; DATA = Atmospheric

26 February 2021 | Deepak Tiwari | XIX International Workshop on Neutrino Telescopes | 9 ν from WIMP annihilation in the Sun

The number of WIMPs N(t) in the core of the Sun:

C (σ =10-40 cm2) d 2 SD SD (N) = C − C N − EN 1024 A C (σ =10-44 cm2) dt SI SI

23 )

-1 10 C = Capture Rate, CA = Annihilation Rate term, E = Evap-

2 C (s oration Rate and Annihilation rate : ΓA = CAN /2. Solv- 22 ing and neglecting E : 10

1021 1 2 ΓA = C tanh (t/τ) 2 20 40 60 80 100 mχ (GeV)

τ = (CC )−1/2 equilibration time. t ' 4.5×109 years. 102 A ντ ντ

10 νµ νµ )

Equilibrium is assumed for the sun, hence : •1 νe νe

s 1 + • •2 τ τ −1 m 10

1 •1 g g ΓA = C −2 2 10 b b (GeV ν 10−3 c c Φ s s ΓA ∝ C ∝ σWIMP−nucleon cross section −4 10 u u 10−5 d d dΦν ΓA X dNi 5 10 15 20 25 = BRi dΩdtdE 4πR2 dE Eν (GeV) ν i=1 ν

26 February 2021 | Deepak Tiwari | XIX International Workshop on Neutrino Telescopes | 10 Background suppression scheme

θ90 : Cone half angle containing 90% of the signal events.

0.02 40 c c b b τ+ τ- channel, ICAL g g 0.015 30 τ+ τ• mχ=50 GeV ν ν

mχ=25 GeV ) ° 0.01 Landau fit ( 20 90 θ

distribution (arbritary units) 0.005 10 ν

0 0 10 20 30 40 50 60 70 80 90 θ ° 0 νµ ( ) 20 40 60 80 100 mχ (GeV) 40 c c The value of corresponding b b I θνµ g g 30 τ+ τ• to 90% of integral of the ν ν ) ° distribution of ν µ scatter ( 20 90 θ

− angle, gives θ90. 10 ν 0 20 40 60 80 100 mχ (GeV)

26 February 2021 | Deepak Tiwari | XIX International Workshop on Neutrino Telescopes | 11 Background suppression scheme

INO(9o 58’ 0’’ N, 77o 16’ 0’’ E) ×10−3 exposure int. surface 350 0.25 300 )

0.2 •1 250 φ

•1 θ )

° 200 0.15

νµ (parent) ( φ 150 0.1

100 Probability( 0.05 50 θνµ(θ90) scatter angle cone 0 0 0 20 40 60 80 100 120 140 160 180 θ (°) µ track(θ,φ) at ICAL 102 25

20 I Take a bkg muon track, put a θ90 15 10

cone around it, compute the (GeV) µ intergrate the solar exposure on E 10 5

the cone surface, and assign Events (50 kt x 10 years)

1 0 the intergral as a weight to the −1 −0.8−0.6−0.4−0.2 0 0.2 0.4 0.6 0.8 1 muon event. cos θ

26 February 2021 | Deepak Tiwari | XIX International Workshop on Neutrino Telescopes | 12 Searches for WIMP annihilation in the sun

−35 10 −39 DAMA/LIBRA 10 CDMSLITE DAMA/LIBRA b b IC

−36 SIMPLE −40 CoGeNT τ+ τ• IC 10 10 + • τ τ ICAL b b ICAL b b IceCube 10−41 b b SK 10−37 PICASSO CDSM II Si ) ) + • 2 2 −42 τ τ SK CRESST II 10 SuperCDMS −38 PICO•60 Baksan b b (cm 10 (cm −43 SI SD b b ICAL b b SK 10 σ σ

ν ν ICAL + • −39 τ τ ICAL −44 • 10 + • + IceCube 10 Baksan τ τ τ τ τ+ τ• SK 10−45 XENON•1T 2017 10−40 LUX•2017 ICAL ν ν 10−46 10−41 10 102 10 102 mχ (GeV) mχ (GeV)

Sandhya Choubey, DT, Anushree Ghosh, JCAP 1805 (2018) no.05, 006

26 February 2021 | Deepak Tiwari | XIX International Workshop on Neutrino Telescopes | 13 Searches for WIMP annihilation in the earth

1015 102 56Fe ντ ντ 1014 28 10 ν ν 24 Si ) µ µ 16 Mg

•44 O •1 13 σ =10 cm2 ) 10 SI

s ν ν •1 1 e e •2 (s + • C τ τ

Γ 12

10 m −1 •1 10 g g −2 1011 10 b b (GeV ν 10−3 c c 10 102 Φ s s m (GeV) −4 χ 10 u u 10−5 d d 1 2 t⊕ −1/2 5 10 15 20 25 Γ⊕ = C⊕ tanh , τ = (C⊕CA) Eν (GeV) 2 τ⊕ 0.45 ) -1

t ) ⊕ θ 0.4 ΓA ∝ C ∝ σWIMP−nucleon cross section τ ∝ hσ vi >

⊕ SIGNAL REGION 0.35 mχ=5 GeV 0.3 mχ=50 GeV dΦν ΓA X dNi 0.25 = BR mχ=100 GeV 2 i dΩdtdE 4πR dE 0.2 ν ⊕ i=1 ν 0.15 Angular probability distribution of reconstructed events 0.1 0.05 Atmospheric background

at ICAL due to WIMP annihilations in the Earth. For Event Probability (0.025 Cos −26 3 −1 −3 0 hσvi = 3 × 10 cm s , ρ = 0.3 GeV cm and −1 −0.8 −0.6 −0.4 −0.2 0 0.2 0.4 0.6 0.8 1 −38 2 θ σSI = 10 cm . Cos z

26 February 2021 | Deepak Tiwari | XIX International Workshop on Neutrino Telescopes | 14 Searches for WIMP annihilation in the earth

10−40 10−36 ANTARES bb −37 τ+τ• ICAL bb − ANTARES 10 41 + • + • 10 ANTARES νν −38 IC86 τ τ ICAL τ τ IceCube 2016 τ+τ• 10 ICAL νν + • −42 CTA τ τ 10−39 10 FERMI•LAT τ+τ• −40 )

) 10 2 2 −43 + • 10 −41 SK τ τ EQUILIBRIUM 10 (cm (cm −42

− SI + • SI 44 10 τ τ ANTARES

10 ICAL b b σ σ

+ • ICAL τ τ 10−43 − ICAL νν 45 −44 10 LUX 2017 10 LUX 2017 DARKSIDE 2015 XENON•1T −45 −46 10 PANDA 2017 10 −46 10 XENON•1T 2017 −47 −47 10 − − − − − − 10 10 30 10 29 10 28 10−27 10 26 10 25 10−24 10 23 10−22 10−21 20 40 60 80 100 σ 3 •1 m (GeV) < A v> (cm s ) χ DT,Sandhya Choubey, Anushree Ghosh [JHEP 1905 (2019)039]

26 February 2021 | Deepak Tiwari | XIX International Workshop on Neutrino Telescopes | 15 ν due to WIMP annihilation in the galactic center At energy E and in the direction of G.C. the ﬂux dΦ/dE integrated over the solid angle ∆Ω = 2π(1 − cosΨ) is given by: dΦν dΦν (E, Ψ) = (E) × J(∆Ω) dEν dEν

106 1 105 NFW Channels - − e+ e BURKERT 10 1 ) µ+ µ- -3 3 ) 10

-1 EINASTO τ+ τ- −2 10 q q 10 (GeV c c ν −3 R b b 10 (r) (GeV cm + ρ

g g −1 − 10 dN/dE 10 4 γ γ ν ν e e − − ν ν 3 10 5 µ µ 10 ν ν τ τ − − − − − 10 5 10 4 10 3 10 2 10 1 1 10 102 10−6 5 10 15 20 25 30 r (kpc) Eν (GeV) The J-Factor is given by: dΦν 1 hσAvi X dNν (E) = BRf dE 4π m2 δ dE ∆Ω ν χ f ν Z Z J(∆Ω) = ρ2dldΩ hσAvi velocity-averaged WIMP annihilation cross section 0 l.o.s ν spectra for a 30 GeV WIMP taken from PPPC4DMID [Cirell et al.] Due to core-cusp problem, results are quoted for various density proﬁles.

26 February 2021 | Deepak Tiwari | XIX International Workshop on Neutrino Telescopes | 16 Background suppresion scheme

Galactic Center Visibility probability @INO(9o 58' 0'' N, 77o 16' 0'' E) ) ) ° -1 φ

( 350

φ 0.005 -1

ZENITH 300 νµ θνµ 0.004

250 Probability (

GC 200 0.003

150 Ψ 0.002 100

0.001 50

0 0 0 20 40 60 80 100 120 140 160 180 Ψµ θ ° zenith ( )

ICAL Ψ used for calculating signal rate and acceptance cone for background suprression. Signal acceptance cone for WIMP annihilation in the GC

24 Ψ : Angle b/w µ track and GC 22 20 b b µ+ µ- θνµ 18 τ+ τ- )

° ν ν ( 16 Ψ 14 12 10 8

20 40 60 80 100 µ− mχ (GeV)

26 February 2021 | Deepak Tiwari | XIX International Workshop on Neutrino Telescopes | 17 Searches for WIMP annihilation in the galactic centre

−21 10−21 10 b b ICAL ν ν )

) µ µ -1 -1 NFW τ+ τ- s s - 3 + 3 BURKERT µ µ EINASTO −22 10−22 10 v> (cm v> (cm A A σ σ < ν ν

< µ µ

− 10−23 10 23

10 20 30 40 50 60 70 80 90 100 10 20 30 40 50 60 70 80 90 100

mχ (GeV) mχ (GeV)

10−21 µ+ µ- ICAL-GC ANTARES GC IC-79 GC −22 10 ν ν νµ νµ, EINASTO µ µ ICAL-GC + - ) ) µ µ SK -1 -1 −23 s s

3 3 10 With Systematics νµ νµ SK

Without Systematics 10−24 v> (cm v> (cm A A σ σ

< < − −23 10 25 10 Natural Scale

10−26 FERMI-LAT 2008-2014

10 20 30 40 50 60 70 80 90 100 1 10 102 mχ (GeV) mχ (GeV)

PhD thesis, DT

26 February 2021 | Deepak Tiwari | XIX International Workshop on Neutrino Telescopes | 18 Summary & Outlook

I Understanding the nature of dark matter is one of the major goals of the contemporary physics and astrophysics. I In that pursuit, we perform a study of muon events arising at ICAL due to neutrinos from WIMP annihilation in the sun, earth and galactic centre for several annihilation channels and WIMP masses upto 100 GeV. I With an effective atmospheric background suppression scheme, the expected sensitivity limits for ICAL are quite competitive to other neutrino experiments. I With a more rigorous analysis, better sensitivity could be achieved. I Plans to extend this analysis to probe other dark matter models such as inelastic DM. I This analysis offer a complementary approach to other dark matter searches.

26 February 2021 | Deepak Tiwari | XIX International Workshop on Neutrino Telescopes | 19 Thank you!

26 February 2021 | Deepak Tiwari | XIX International Workshop on Neutrino Telescopes | 20 Back-up slides

26 February 2021 | Deepak Tiwari | XIX International Workshop on Neutrino Telescopes | 21 Statistical analysis

With THEORY = Atmospheric + DM ; DATA = Atmospheric, we calculate: χ2 = χ2(µ−) + χ2(µ+) where χ2(µ±) = ex ± Ni Nj th ± ex ± ex ± Nij (µ ) l ±2 min ± 2 N ( ) N ( ) + 2N ( ) ln + , ξ i=1 j=1 ij µ ij µ ij µ Nth(µ±) k=1 ξk k − ij P Pth l ± ±2 P Nth(µ±) = N0 (µ±) 1 + πk ξ + (ξ ), ij ij k=1 ij k O k 0th ± P N ij (µ ) : predicated no. of events. ex ± ± Nij (µ ) : ‘observed’ number of µ events. k th πij : correction factors due to the k systematic uncertainty. ± ξk : pull parameters. I 20 % error on ﬂux normalisation, I 10 % error on cross-section I 5 % uncorrelated error on the zenith angle distribution of atmospheric neutrino ﬂuxes I 5 % tilt error I 5 % overall error to account for detector systematics

26 February 2021 | Deepak Tiwari | XIX International Workshop on Neutrino Telescopes | 22 ν due to WIMP annihilation in the galactic center The ν ﬂuxes due to WIMP annihilation at GC is expressed as the product of a particle physics term by an astrophysical contribution J.

P At energy E and in the direction of lmax G.C. the ﬂux dΦ/dE integrated over the solid angle RMW Ψ GC ∆Ω = 2 (1 cosΨ) is given by: R π Earth SC −

2 2 2 v lmax = uR R sin Ψ + R cos Ψ u MW SC SC dΦν dΦν t − ∆Ω = 2π(1 cos Ψ) (E, Ψ) = (E) J(∆Ω) − dEν dEν × dΦ 1 σ v dN ν (E) = A BR ν h 2 i f dEν 4π m δ dEν χ f l : distance between a point P and the earth ρsc : local X dark matter density, Rsc : solar radius. σAv velocity-averaged WIMP anni- hilationh i cross section BR : Branching Ratio

26 February 2021 | Deepak Tiwari | XIX International Workshop on Neutrino Telescopes | 23