Andrey Formozov The University of Milan INFN Milan

Transcription

1 T h e i nv e s t i g a t i o n of l i q u i d s c i n t i l l a t o r p ro p e r t i e s, e n e r g y a n d s p a t i a l re s o l u t i o n fo r JUNO re a c t o r n e u t r i n o e x p e r i m e n t Andrey Formozov The University of Milan INFN Milan 1

2 v Neutrino has no charge has a tiny mass weakly interacts with matter v W Z l v v three types (flavors) of neutrino neutrino can change its flavor due to oscillations νe νμ ντ 2

3 v How to detect? Small cross section Cosmic background Surrounded radioactivity Shielding Radioactivity of the materials Huge target mass Underground laboratory Purification 3

4 Solar neutrino MeV 4

5 Geo anti-neutrino 0-3 MeV 5

6 SN 1987A Supernova neutrino 1-40 MeV 6

7 Atmospheric neutrino GeV 7

8 Reactor anti-neutrino 0-10 MeV 8

9 JUNO: multi-purpose experiment Main purpose: Neutrino Mass Hierarchy 9 determination

10 Neutrino Mass Hierarchy determination νe > νμ > ντ > Flavor eigenstates 2 flavor case: vμ > v2 > ve > = vμ > ve > θ v1 > ν1 > ν2 > ν3 > m1 m2 m3 V cos θ Mass eigenstates sin θ ij sin θ cos θ v1 > v2 > In 3 flavor case: θ1,θ2,θ3 10

11 Neutrino Mass Hierarchy determination Absolute masses m1, m2, m3 are unknown. The oscillation probability P = <νi νj > 2 α, β = e, μ, τ does not depend on the absolute value of masses, but on: Δm2ij = mi2 m2j Δm221 > 0 m23 m22 m21 m22 m21 m23 Δm231 Δm232 Normal Inverse 11

12 Neutrino Mass Hierarchy determination ν?ν Supernova fluxes and nucleosynthesis Dirac or Majorana? Mass Hierarchy P(ν ν)? P(ν ν) CP-violation Σmν cosmology Origin of neutrino mass 12

13 JUNO experiment Ultra pure liquid scintillator: 20 Ktons Beijing Photomultipliers: (20 inches) (3 inches) 700 m underground Water Cherenkov pool 53 km from two multi-core nuclear power plants Start in 2020 Hong-Kong JUNO 13

14 v MeV γ νe + p n + e MeV e+ γ p n γ PMT s current Time 230 μs INVERSE BETA DECAY POSITRON PROPAGATION AND ANNIHILATION NEUTRON CAPTURE 14

15 PURIFICATION Th-232 U-238 K-40 Rn-222 Kr-85 Ar-39 Pb-210 Al Wa Ni Di te tr 20 st 3 r og il c ex en ol la Radioactive purity tr um ti ac n on ti High optical transparency on Fi lt ra ti on pu mp 15 in g

16 ENERGY RESOLUTION HIGH ENERGY RESOLUTION: 3 % for 1 MeV is crucial for Neutrino Mass Hierarchy determination 16 LARGE PHOTO-CATHODE COVERAGE: 75 %

17 Neutrino Mass Hierarchy determination νe + p n + e + Normal Inverse Positron spectrum: 3% energy resolution SMEARING and SHIFT are DANGEROUS! 17

18 Consider our detector is ideal... Quenching effect Q E Q(E) E Real detector: non-linearity and energy resolution Q Q(E) Q σdetector2 + σscint2 β α α E E β Q(E) Q Light yield depends on the type of a particle.the more de/dx, the less phot. 5 MeV beta: ~50000 photons 5 MeV alpha: ~5000 photons Light yield is non-linear Intrinsic degradation of the energy resolution is expected! 18

19 Experimental setup Ee vs Qpmt Ee = Eγ E γ Scintillator σsetup vs σmeasured HPGe CELL WITH SCINTILLATOR CELL WITH LAB SETUP JUNO Q(E) Q(E) σsetup2 + σscint2 σjuno2 + σscint2 HPGe SOURCE PMT 19

20 Monte Carlo simulation Ideal detector Q(E) σsetup2 + σscint2 20

21 Summary JUNO experiment will have a rich scientific program The experiment has technological challenges: purification, energy resolution and many others Before data-taking, a large amount of research activities should be performed. Non-linear response and energy resolution is necessary to examine in order to determine Neutrino Mass Hierarchy 21

22 Thank you for your attention! So why did we want to detect the free neutrino? Because everybody said, you couldn t do it Clyde Cowan 22

23 Backup slides 23

24 Some open questions of the neutrino physics Dirac or Majorana Normal or inverted mass ordering Mass of the neutrino (MH) Octant of θ23 CP-violation phase(s) (MH) Unitarity test, sterile neutrino and many others... 24

25 Oscillations in case of two generations ve > D S Aee = <ve ve > = 1 2 Pee = Aee = 1 ve > flux ~ 1/r 2 25

26 Oscillations in case of two generations ve vμ V cos θ sin θ ve > = sin θ cosijθ vμ > v vμ > ve > v1 > v2 > 2> θ v1 > 26

27 Oscillations in case of two generations ve > = cosθ v1 > - sinθ v2 > D S ve > = sinθ v1 > + cosθ v2 > Aee = <ve ve > 1 flux 1/r 2 27

28 Theory and experiment 28 1

29 Backup slides 29

30 31

31 Daya Bay &Reno&DC KamLAND 53 km JUNO 32

32 Experimental setup 33

33 Strategy Analysis of all published measurements Performance of the experiment; Monte Carlo simulations. The development of a phenomenological model. Simulation and analysis of the JUNO experiment 34

34 SOFTWARE SIMULATION Neutrino energy Positron energy Optical photons PMT s Hits PMT s Charge RECONSTRUCTION SniPER is a new framework for large scale neutrino experiments Algorithms, data structures and MC-generators are controlled by a single script One instrument - for more then 60 collaborators! 35

35 36

36 Super-Kamiokande and SNO TAKAAKU KAJITA ARTHUR B. MCDONALD 2015

37 SNO experiment vμ vτ ve 38