Oscillation Physics at INO

1. Oscillation Physics at INO Debasish Majumdar (On behalf of INO collaboration) Saha Institute of Nuclear Physics Kolkata

2. India-basedNeutrino Observatory An underground facility in India for neutrino physics The proposed detector is an Iron CALorimeter (ICAL) detector ICAL consists of iron plates stacked horizontally interleaved with glass RPC detectors

3. Purpose of INO • To see the actual oscillation of neutrinos • Study of matter effects through electric charge • identification • To identify the mass hierarchy (normal or inverted) • To measure the 13 mixing angle 13 • Study of CP and CPT violation A) Study atmospheric neutrinos B) End detector of a long base-line experiment

4. For 3- Flavours cij=cos ij sij =sin ij For 2- Flavours P() = 1 - sin22 sin2 [1.27 m2 (L/E)]

5. Two flavour oscillation formula: P() = 1 - sin22 sin2 [1.27 m2 (L/E)], L in Km, E in GeV For oscillation studies one should have L the path-length of the  E the energy of the  +Z d R  L L = (R-d)cos2() +  [R2 - (R-d)2sin2()]

6. P() = 1 - sin22 sin2 [1.27 m2 (L/E)], • In the absence of oscillation Up-going events = Down going events  • In presence of oscillation Down-going neutrinos suffers no or negligible oscillation [as they traverse shorter length (L)] Up-going neutrinos traverse longer length (L)  Oscillates effectively plot shows oscillatory behaviour

7. Mirroring of down going events For no oscillation Down going  Down going events in any direction  Up going events from opposite direction True L  Detector Due to oscillation Up going events < down going events in the opposite direction -  Earth + Atm L= mirrored L Up going  “Mirror” down going ’s with angle -  consider them no oscillation standard for up going ’s at angle   Measure of oscillation

8. Detector Configuration Horizontal alignment : (ICAL-H) No. of Chambers = 8 along y axis No. of Modules = 16 along x axis No. of Layers = 140 along z axis Dimension : 32m  16m  12m Mass = 32 kTon For 100 kTon Horizontal stacking dimension is changed as x = 96m, y = 16m, z = 12m

9. SIMULATIONS WITH ICAL DETECTOR a) NUANCE event generator Given the detector specifications and atmospheric neutrino flux (Burtol and/or Honda) it generates neutrino events at ICAL (product particles and their production vertex at ICAL) b) GEANT 3.2 Simulation Code The outputs of NUANCE are the inputs to GEANT GEANT propagates the product particles through ICAL and Gives as outputs, their hit points, momenta, time information etc. c) Analyse the GEANT output

10. GENERATING OSCILLATED EVENTS USING NUANCE Output details : Event no., particle id,x, y, z, px, py, pz Oscillation probability P() = 1 - sin22 sin2 [1.27 m2 (L/E)], m2 =2.0  10-3 eV2,sin22 =1 Case I:Oscillation incorporated inside NUANCE itself Case II:From NUANCE output , prob. of each event is calculated using the oscillation formula Now after each event call a random number. If prob.> Random number, then that event survives. If prob.< Random number, then that event is ignored Resulting Output is Oscillated Nuance Data

11. SIMULATION USING GEANT 3.2 CODE A GEANT based simulation programme is written A 3-D cartesian coordinate system is used with Origin at the centre of ICAL Z-axis pointing upwards Detector dimensions -1600 cm < x < +1600 cm -800 cm < y < +800 cm -600 cm < z < +600 cm (32 m x 16 m x 12 m) Magnetic Field Bx = 0 = By, Bz = 1 Tesla Programmes are also written to read a mapped magnetic field in x-y plane (Bx, By, 0) and use it for GEANT simulation Contd….

12. Output of GEANT based simulation programme Co-ordinates of the successive hit points and their momenta at every hit point (i.e. x,y,z, px, py, pz) of the product particles (mainly ’s and hadrons), propagating through ICAL) From (x,y,z) coordinates tracks (trajectories) are constructed Trajectories are helical for charged particles (due to B) with continuously shrinking radius due to energy loss Y (cm) Y (cm) X (cm) X (cm)

13. Finding L and E of incident  from GEANT simulated tracks Two types of analyses Analysis with fully contained (FC) events only Analysis with both FC and partially contained (PC) events L is calculated by finding the zenith (polar angle) L = (R-d)cos2() +  [R2 - (R-d)2sin2()]  is calculated from the track and it’s projection on x-y plane Energy E is calculated in two ways FC events From average path length FC + PC events Using the track geometry (bending due to magnetic field B)

14. Track Selection • FC events • i) A neutrino event must have a track with 12 hits or more • ii) The event has no more than two tracks • FC + PC events • Number of hits > 9 • Zenith angle cuts • L/E Resolution • We define Resolution function in terms of • (L/E)reso = {(L/E)true – (L/E)ex}/(L/E)true • Where, • L/E(true) : Parameter estimated from the NUANCE output only () • L/E(exp) : Parameter estimated after passing through GEANT

15. Up/Dn vs L/E plot showing oscillation

16. Up/Dn vs L/E plot showing oscillation

17. Resolution Plots

18. Resolution Plots

19. Resolution Plots

20. Extraction of oscillation parameters through 2 analysis The 2 is defined as, 2= {[(Up/down)theory – (Up/Down)Expt.]/Error}2 Theory: Data obtained fromNUANCEoutput folded with resolution. Expt.: Results obtained fromGEANTsimulation.

21. Contour Plot

22. Contour Plot

23. Oscillation Physics at INO with 3 ’s (Three mixing angles and two mass square differences) INO will address Observance of oscillation and precise measurement of oscillation parameters (study of matter effects) Sign of Determination of Probing CP violation STUDY A) Atmospheric Neutrinos B) Neutrinos from neutrino factories

24. 3 Direct (Normal) hierarchy atm 32 > 0 2 solar ij = mij 1 2 solar 1 atm Inverted hierarchy 32 < 0 3

25. For 32  0,  For neutrinos  For anti-neutrinos For 32  0,just the reverse

27. Determination of sign of 32 (From matter induced asymmetry) ANis different for normal mass hierarchy (32 > 0) and inverted mass hierarchy (32 < 0)

28. Probing neutrino beam from neutrino Factories ( ICAL as end detector of long baseline experiment) • Beam from  storage rings with long straight sections • Intense, high luminosity neutrino beams from  decaying in the straight section , • Look for wrong sign  Sign of 32 Determination of 13 Probing CP violation in the leptonic sector

29. PUSHEP Rammam JHF (4828) JHF (6556) CERN (6871) CERN (7145) FERMILAB (10480) FERMILAB (11300) Magic baseline ~ 7250 km (No CP)

30. Wrong sign  events vs 32 For small 13 and 32 > 0 e  enhanced Baseline from JHF (A~ E/ 32)

31. The achievable sin13 at INO vs threshold energy of  detection

32. The ratio of wrong sign  events and opposite sign  events for the storage ring vs base length Probing CP vs

33. Discussions 1) INO has the potential to measure oscillation dip and the oscillation parameters 2) ICAL at INO is capable of probing the measure of 13 and sign of 23 from atmospheric neutrinos 3) ICAL at INO can be a very effective far end detector for long baseline experiments 4) With its charge discrimination capability ICAL at INO can be very efficient to determine not only oscillation but also mixing angle 13 and the mass hierarchy (thus substantiating the atmospheric neutrino measurements) And most importantly 5) Probing the CP violation-the holy grail of Physics in the lepton sector

34. INO marches ahead Have a good day