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Neutrino Experiments with Liquid Scintillator Detectors an Overview

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Neutrino Experiments with Liquid Scintillator Detectors an Overview Neutrinos Detection principles Experiments Summary Neutrino Experiments with Liquid Scintillator Detectors An Overview Daniel Bick Institut fur¨ Experimentalphysik Hamburg University Hamburg Student Seminar, October 29th 2007 Daniel Bick Neutrino Experiments with Liquid Scintillator Detectors 1 Neutrinos Detection principles Experiments Summary 1 Neutrinos General facts Neutrino Mixing Neutrinos 2 Detection principles Neutrino detection Liquid Scintillators What can be investigated 3 Experiments KamLAND Borexino Propects 4 Summary Daniel Bick Neutrino Experiments with Liquid Scintillator Detectors 2 Neutrinos Detection principles Experiments Summary 1 Neutrinos General facts Neutrino Mixing Neutrinos 2 Detection principles Neutrino detection Liquid Scintillators What can be investigated 3 Experiments KamLAND Borexino Propects 4 Summary Daniel Bick Neutrino Experiments with Liquid Scintillator Detectors 2 Neutrinos Detection principles Experiments Summary 1 Neutrinos General facts Neutrino Mixing Neutrinos 2 Detection principles Neutrino detection Liquid Scintillators What can be investigated 3 Experiments KamLAND Borexino Propects 4 Summary Daniel Bick Neutrino Experiments with Liquid Scintillator Detectors 2 Neutrinos Detection principles Experiments Summary 1 Neutrinos General facts Neutrino Mixing Neutrinos 2 Detection principles Neutrino detection Liquid Scintillators What can be investigated 3 Experiments KamLAND Borexino Propects 4 Summary Daniel Bick Neutrino Experiments with Liquid Scintillator Detectors 2 Neutrinos Detection principles General facts Experiments Neutrino Mixing Summary 1 Neutrinos General facts Neutrino Mixing Neutrinos 2 Detection principles Neutrino detection Liquid Scintillators What can be investigated 3 Experiments KamLAND Borexino Propects 4 Summary Daniel Bick Neutrino Experiments with Liquid Scintillator Detectors 3 Neutrinos Detection principles General facts Experiments Neutrino Mixing Summary Some general aspects on the neutrino The (electron-)neutrino was predicted by Wolfgang Pauli in 1930. It was experimentally discovered in 1956 by Reines and Cowan. There is one corresponding neutrino for each charged lepton. νe νµ ντ e− µ− τ − Daniel Bick Neutrino Experiments with Liquid Scintillator Detectors 4 Neutrinos Detection principles General facts Experiments Neutrino Mixing Summary Neutrinos Sources Many neutrino sources - both natural and man made - exist: β-decays (up to some MeV) Atmospheric neutrinos νµ, ν¯µ, νe , ν¯e from π-decays (100 MeV - 10 TeV) Solar neutrinos: νe (< 2 MeV) Reactor neutrinos: ν¯e (up to 10 MeV) Neutrino beams: mainly νµ (some 10 GeV) Geoneutrinos: ν¯e (< 3:3 MeV) Supernovae: all flavors (some 10 MeV) Supernova bursts Relic neutrinos Daniel Bick Neutrino Experiments with Liquid Scintillator Detectors 5 Neutrinos Detection principles General facts Experiments Neutrino Mixing Summary Neutrino Mixing Neutrino flavor eigenstates jναi differ from their mass eigenstates jνi i. There are three mass eigenstates ν1; ν2; ν3 corresponding to the charged-lepton mass eigenstates e; µ and τ. Eigenstates are connected by the mixing matrix UPMNS . ∗ jνi i = Uiαjναi jναi = Uiαjνi i: Xα Xi Daniel Bick Neutrino Experiments with Liquid Scintillator Detectors 6 Neutrinos Detection principles General facts Experiments Neutrino Mixing Summary Neutrino propagation The propagation of the mass eigenstates is described by: 2 mi Ei t−p L −i L jνi (t)i = e i jνi (0)i = e 2E jνi (0)i 2 m2 −i i L P ! e 2E να νβ = να νβ Xi Neutrino mixing leads to oscillations. ∗ ∗ 2 2 L P ! = δ − 4 Re(U U U j U ) sin ∆m να νβ αβ αi βi α βj ij 4E Xi>j ∗ ∗ 2 L + 2 Im(U U i U j U ) sin ∆m αi β α βj ij 2E Xi>j 2 2 2 With ∆mij = mi − mj Daniel Bick Neutrino Experiments with Liquid Scintillator Detectors 7 Neutrinos Detection principles General facts Experiments Neutrino Mixing Summary The mixing matrix atmospheric cross-mixing −iδ 1 0 0 cos θ13 0 sin θ13e U = 0z 0 cos θ23}| sin θ23 1{ × 0z 0 }|1 0 1{ 0 − sin θ cos θ − sin θ eiδ 0 cos θ @ 23 23A @ 13 13 A iα =2 cos θ12 sin θ12 0 e 1 0 0 iα =2 × 0− sin θ12 cos θ12 01 × 0 0 e 2 01 0 0 1 0 0 1 @ A @ A solar majorana phases | {z } | {z } −iδ c12c13 s12c13 s13e iδ iδ U = 0−s12c23 − c12s23s13e c12c23 − s12s23s13e s23c13 1 s s − c c s eiδ −c s − s c s eiδ c c @ 12 23 12 23 13 12 23 12 23 13 23 13 A Daniel Bick Neutrino Experiments with Liquid Scintillator Detectors 8 Neutrinos Detection principles General facts Experiments Neutrino Mixing Summary The mixing matrix atmospheric cross-mixing −iδ 1 0 0 cos θ13 0 sin θ13e U = 0z 0 cos θ23}| sin θ23 1{ × 0z 0 }|1 0 1{ 0 − sin θ cos θ − sin θ eiδ 0 cos θ @ 23 23A @ 13 13 A cos θ12 sin θ12 0 × 0− sin θ12 cos θ12 01 0 0 1 @ A solar | {z } −iδ c12c13 s12c13 s13e iδ iδ U = 0−s12c23 − c12s23s13e c12c23 − s12s23s13e s23c13 1 s s − c c s eiδ −c s − s c s eiδ c c @ 12 23 12 23 13 12 23 12 23 13 23 13 A Daniel Bick Neutrino Experiments with Liquid Scintillator Detectors 8 Neutrinos Detection principles General facts Experiments Neutrino Mixing Summary The mixing matrix atmospheric cross-mixing −iδ 1 0 0 cos θ13 0 sin θ13e U = 0z 0 cos θ23}| sin θ23 1{ × 0z 0 }|1 0 1{ 0 − sin θ cos θ − sin θ eiδ 0 cos θ @ 23 23A @ 13 13 A cos θ12 sin θ12 0 × 0− sin θ12 cos θ12 01 0 0 1 @ A solar | {z } −iδ c12c13 s12c13 s13e iδ iδ U = 0−s12c23 − c12s23s13e c12c23 − s12s23s13e s23c13 1 s s − c c s eiδ −c s − s c s eiδ c c @ 12 23 12 23 13 12 23 12 23 13 23 13 A Daniel Bick Neutrino Experiments with Liquid Scintillator Detectors 8 Neutrinos Detection principles General facts Experiments Neutrino Mixing Summary Matter Effects (simplified) Oscilliation in matter differs from vacuum oscillatons: Coherent forward scattering of neutrinos from particles along their way can have an effect. Coherent forward scattering via W exchange occurs for electron type neutrinos. Scattering via Z exchange for all neutrino types ! effect cancels out. This means that neutrinos in matter have a different effective mass than neutrinos in vacuum! Matter effects depend on the neutrino energy. Larger effect for more energetic neutrinos. Daniel Bick Neutrino Experiments with Liquid Scintillator Detectors 9 Neutrinos Neutrino detection Detection principles Liquid Scintillators Experiments What can be investigated Summary 1 Neutrinos General facts Neutrino Mixing Neutrinos 2 Detection principles Neutrino detection Liquid Scintillators What can be investigated 3 Experiments KamLAND Borexino Propects 4 Summary Daniel Bick Neutrino Experiments with Liquid Scintillator Detectors 10 Neutrinos Neutrino detection Detection principles Liquid Scintillators Experiments What can be investigated Summary Detection methods Three major methods of detecting neutrinos: Cerenkˇ ov Detectors (Ethr ' 5 MeV). Radiochemical Detectors (e.g. C2Cl4: Ethr = 814 keV, Ga: Ethr = 233 keV). No energy measurement possible. Liquid Scintillation Detectors (Ethr ' 200 keV for ν and Ethr ' 1:8 MeV for ν¯) Daniel Bick Neutrino Experiments with Liquid Scintillator Detectors 11 Neutrinos Neutrino detection Detection principles Liquid Scintillators Experiments What can be investigated Summary Liquid Scintillators Organic liquid scintillators are aromatic hydrocarbon compunds containing benzene-ring structures. Passing particles deposit ionizing energy in the scintillator, exciting the free valence electrons of the benzene-rings. Scintillation light is emitted due to transitions from excited states to the ground state. Daniel Bick Neutrino Experiments with Liquid Scintillator Detectors 12 Neutrinos Neutrino detection Detection principles Liquid Scintillators Experiments What can be investigated Summary ν¯e-detection via the inverse β-decay Inverse β decay on protons: + p + ν¯e ! e + n CC reaction of a proton and an antineutrino. (cross section in the order of 10−42 cm2). The positron anihilates with some electron imediately emitting ¯ two γ's. Visible energy: Eprompt = Eν¯e − En − 0:8 MeV The neutron will be captured after a short delay (typically around 200 µs), releasing 2.2 MeV. Coincidence signal between the prompt positron and the gammas from the delayed neutron-capture. Reaction threshold: 2 2 (Mn + Me ) − Mp Eν,min = = 1:806 MeV: 2Mp Daniel Bick Neutrino Experiments with Liquid Scintillator Detectors 13 Neutrinos Neutrino detection Detection principles Liquid Scintillators Experiments What can be investigated Summary ν¯e-detection via the inverse β-decay Inverse β decay on protons: + p + ν¯e ! e + n CC reaction of a proton and an antineutrino. (cross section in the order of 10−42 cm2). The positron anihilates with some electron imediately emitting ¯ two γ's. Visible energy: Eprompt = Eν¯e − En − 0:8 MeV The neutron will be captured after a short delay (typically around 200 µs), releasing 2.2 MeV. Coincidence signal between the prompt positron and the gammas from the delayed neutron-capture. Reaction threshold: 2 2 (Mn + Me ) − Mp Eν,min = = 1:806 MeV: 2Mp Daniel Bick Neutrino Experiments with Liquid Scintillator Detectors 13 Neutrinos Neutrino detection Detection principles Liquid Scintillators Experiments What can be investigated Summary ν¯e-detection via the inverse β-decay Inverse β decay on protons: + p + ν¯e ! e + n CC reaction of a proton and an antineutrino. (cross section in the order of 10−42 cm2). The positron anihilates with some electron imediately emitting ¯ two γ's. Visible energy: Eprompt = Eν¯e − En − 0:8 MeV The neutron will be captured after a short delay (typically around 200 µs), releasing 2.2 MeV. Coincidence signal between the prompt positron and the gammas from the delayed neutron-capture. Reaction threshold: 2 2 (Mn + Me ) − Mp Eν,min = = 1:806 MeV: 2Mp Daniel Bick Neutrino Experiments with Liquid Scintillator Detectors 13 Neutrinos Neutrino detection Detection principles Liquid Scintillators Experiments What can be investigated Summary ν¯e-detection via the inverse β-decay Inverse β decay on protons: + p + ν¯e ! e + n CC reaction of a proton and an antineutrino.
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