Neutrinos Leonidas Aliaga The 2019 Undergraduate Lecture Series - - PowerPoint PPT Presentation

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Neutrinos Leonidas Aliaga The 2019 Undergraduate Lecture Series - - PowerPoint PPT Presentation

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Neutrinos Leonidas Aliaga The 2019 Undergraduate Lecture Series July 9, 2019 Outline Introduction How the neutrinos were discovered? Still 0 files What is really the identity of neutrinos? How do we study neutrinos at Fermilab? 2

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Leonidas Aliaga The 2019 Undergraduate Lecture Series July 9, 2019

Neutrinos

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07-09-2019 Leonidas Aliaga | Neutrino Physics 2

Outline

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Introduction How the neutrinos were discovered? What is really the identity of neutrinos? How do we study neutrinos at Fermilab?

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Introduction

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Standard Model of Elementary Particles

+ antiparticles

https://www.physik.uzh.ch

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e e What does elementary particle mean?

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What do we know about neutrinos

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They are abundant: emitted from the sun, other stars, and including the Big Bang are traveling through out space

Millions and millions and millions of neutrinos are also passing through YOU at this very MOMENT! 65 billion of neutrinos / cm2 / sec from the Sun.

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What do we know about neutrinos

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(neutrinos at Fermilab can travel up to 200 Earths before interacting) The probability of their interactions is very small

Neutrino interactions are extremely rare!

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Neutrino and weak interactions

t t

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Neutrino and weak interactions

t t

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Andre De Gouvea: https://www.youtube.com/watch?v=UY1QQr-PZOg

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Andre De Gouvea: https://www.youtube.com/watch?v=UY1QQr-PZOg

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Masses

The difference between the generations is the mass.

ν?

mass (GeV)

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What do we know about neutrinos

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They have very small masses and they change identity

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How the neutrinos were discovered?

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Beta decay problem <= 1930’s

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Unstable nucleus loses energy by emitting an electron transforms an atom into different type of atom

Henri Becquerel Marie Curie Pierre Curie

For instance: Carbon Nitrogen

Electron

C

14 6

N

14 7

13 043.94 MeV/c2 13 043.27 MeV/c2 0.511 MeV/c2

e-

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Beta decay problem > 1930’s

Measured spectrum

(1930) Pauli postulated an additional particle (neutral and very small) in beta decays. (1933) Fermi formulated the theory the weak force to explain the process. (1936) Yukawa proposed W boson as a carrier of the weak force.

16

156 KeV Expected spectrum

n -> p + e- + νe

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Detect Neutrinos from Reactors

Cowan

n p + e- + νe

Nuclear fission: bombarding heavy elements with slow neutrons: artificial radioactivity Neutrons are unstable:

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Neutrinos from Reactors

νe

detector

n u c l e a r r e a c t

  • r

νe + p e+ + n

Cowan

n p + e- + νe

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07-09-2018 Leonidas Aliaga | Neutrino Physics 19

Poltergeist project

Reines Cowan νe

(1956) A team lead by Clyde Cowan and Frederick Reines designed an experiment to detect neutrinos from a reactor. Observed 0.56 counts per hour.

https://permalink.lanl.gov/object/tr?what=info:lanl-repo/lareport/LA-UR-97-2534-02

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Homestake experiment

Still 0 files Ray Davis

(1961) Ray Davis confirmed the detection of solar neutrinos. Neutrino interactions convert Cl-37 into radioactive Ar-37.

It was expected 1 neutrino per day. However, they only saw 1 neutrino every fourth days.

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Homestake experiment

Still 0 files Ray Davis

(1961) Ray Davis confirmed the detection of solar neutrinos. Neutrino interactions convert Cl-37 into radioactive Ar-37.

It was expected 1 neutrino per day. However, they only saw 1 neutrino every fourth days.

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Homestake experiment

Still 0 files Ray Davis

(1961) Ray Davis confirmed the detection of solar neutrinos. Neutrino interactions convert Cl-37 into radioactive Ar-37.

It was expected 1 neutrino per day. However, they only saw 1 neutrino every fourth days.

Our understanding of how our detector behaves is wrong

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07-09-2018 Leonidas Aliaga | Neutrino Physics 23

Homestake experiment

Still 0 files Ray Davis

(1961) Ray Davis confirmed the detection of solar neutrinos. Neutrino interactions convert Cl-37 into radioactive Ar-37.

It was expected 1 neutrino per day. However, they only saw 1 neutrino every fourth days.

Our understanding of how our detector behaves is wrong Is the Solar model wrong?

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07-09-2018 Leonidas Aliaga | Neutrino Physics 24

Homestake experiment

Still 0 files Ray Davis

(1961) Ray Davis confirmed the detection of solar neutrinos. Neutrino interactions convert Cl-37 into radioactive Ar-37.

It was expected 1 neutrino per day. However, they only saw 1 neutrino every fourth days.

Our understanding of how our detector behaves is wrong Is the Solar model wrong? Our understanding on how neutrinos behave is wrong?

https://cdn.journals.aps.org/files/RevModPhys.75.985.pdf

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Atmospheric neutrinos

Cosmic rays (mostly) interact in the upper atmosphere creating a hadronic showers (mostly pions).

νμ νe νμ

Roughly 2:1 muon neutrinos to electron neutrinos expected: Events found in Kamiokande (~3kton WC) 1988

π+ μ+ + νμ e+ + νe + νμ

e-like μ-like

  • Phys. Lett. B205 (1988) 416
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What is really the identity of neutrinos?

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Neutrinos Oscillation

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Create in one flavor, but detect in another flavor

νe e

νµ

µ

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Create in one flavor, but detect in another flavor

Created or detected

νe νμ ντ

States associated to the corresponding lepton

νe e

νµ

µ

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Create in one flavor, but detect in another flavor

Created or detected

νe νμ ντ

States associated to the corresponding lepton

Traveling

ν1 ν2 ν3

States with well determined mass

νe e

νµ

µ

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Create in one flavor, but detect in another flavor

Created or detected

νe νμ ντ

States associated to the corresponding lepton

Traveling

ν1 ν2 ν3

States with well determined mass

They do not match

νe e

νµ

µ

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Create in one flavor, but detect in another flavor

νe νμ ντ ν1 ν2 ν3

= = = + +

ν1 ν2 ν3

+ +

ν1 ν2 ν3

+ +

νe e

νµ

µ

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Create in one flavor, but detect in another flavor

νe νμ ν1 ν2 ν3

= = + +

ν1 ν2 ν3

+ +

distance

νe e νµ µ

νe e

νµ

µ

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Create in one flavor, but detect in another flavor

νe νμ ν1 ν2 ν3

= = + +

ν1 ν2 ν3

+ +

ν1 ν2 ν3

+ +

distance

νe e

νµ

µ

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07-09-2019 Leonidas Aliaga | Neutrino Physics 35

Create in one flavor, but detect in another flavor

νe νμ ν1 ν2 ν3

= = + +

ν1 ν2 ν3

+ +

ν1 ν2 ν3

+ +

distance

νe e

νµ

µ

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07-09-2019 Leonidas Aliaga | Neutrino Physics 36

Create in one flavor, but detect in another flavor

νe νμ

= =

ν1 ν2 ν3

+ +

ν1 ν2 ν3

+ +

distance

νe e

νµ

µ

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07-09-2019 Leonidas Aliaga | Neutrino Physics 37

Create in one flavor, but detect in another flavor

νe νμ ν1 ν2 ν3

= = + +

ν1 ν2 ν3

+ +

ν1 ν2 ν3

+ +

distance

νe e

νµ

µ

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07-09-2019 Leonidas Aliaga | Neutrino Physics 38

Create in one flavor, but detect in another flavor

νe νμ ν1 ν2 ν3

= = + +

ν1 ν2 ν3

+ +

ν1 ν2 ν3

+ +

distance

νe e

νµ

µ

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07-09-2019 Leonidas Aliaga | Neutrino Physics 39

Create in one flavor, but detect in another flavor

νe νμ ν1 ν2 ν3

= = + +

ν1 ν2 ν3

+ +

distance

νe e

νµ

µ

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Create in one flavor, but detect in another flavor

https://www.youtube.com/watch?v=7fgKBJDMO54

νe e

νµ

µ

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Create in one flavor, but detect in another flavor

φ(p,E,r,t)

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Create in one flavor, but detect in another flavor

φ(p,E,r,t)

α, β: e, μ, τ

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If we have only 2 neutrinos…

Each flavor is a superposition of different masses:

α, β: e, μ, τ Δm2 = mi2 - mj2

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The complete view with 3 flavor oscillation

PMNS

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The complete view with 3 flavor oscillation

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The complete view with 3 flavor oscillation

c23 = cosθ23, … s23 = sinθ23, …

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Blue: νμ Black: ντ Red : νe

Oscillation probability for an initial νμ

https://en.wikipedia.org/wiki/Neutrino_oscillation For NOvA FD, L = 810 km and E ~ 2GeV, L/E ~ 405 km/GeV For NOvA ND, L = 1 km and E ~ 2GeV, L/E ~ 0.5 km/GeV

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Current knowledge of the oscillation parameters Normal hierarchy

~0(10-5eV2)

Measured from Sun, atmosphere, reactor and accelerators” We know that m2 > m1, see:

https://en.wikipedia.org/wiki/Mikheyev–Smirnov–Wolfenstein_effect

We do not know if NH: m3 > m1, m2 ….

  • r

IH: m3 < m1, m2

~0(10-3eV2)

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Current knowledge of the oscillation parameters Normal hierarchy

~0(10-3eV2) ~0(10-5eV2)

Inverse hierarchy

Measured from Sun, atmosphere, reactor and accelerators We know that m2 > m1, see:

https://en.wikipedia.org/wiki/Mikheyev–Smirnov–Wolfenstein_effect

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Current knowledge of the oscillation parameters Normal hierarchy Inverse hierarchy

Measured from Sun, atmosphere, reactor and accelerators

θ23 maximal?

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Neutrinos at Fermilab

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Accelerator Neutrino Beam

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Accelerator Neutrino Beam: same concept as the atmospheric neutrino

  • The concept of the neutrino beam from accelerators was proposed

independently by Pontecorvo and Schwartz (1959 - 1960).

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By 1960s….

  • The Standard Model was under construction… many remaining unsolved problems in

the electroweak sector….

For instance, are ν (emitted in β decays) and ν (emitted in π -> μ) identical particles? Is it possible to use high energy ν’s to study weak interactions?

  • The concept of the neutrino beam from accelerators was proposed independently by

Pontecorvo and Schwartz to answer the question…

Yes! we get 1 ν per hour. LEDERMAN SCHWARTZ STEINBERGER

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How to make a neutrino beam

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Fermilab Accelerator Complex Main Injector

Tevatron

LINAC

Booster

NOvA-MINOS- MINERvA BooNE

DUNE (proposed)

Current Neutrino Beams:

  • BNB
  • NuMI
  • Future: LBNE

Fermilab Accelerator Complex

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120 GeV protons strike a graphite target and hadronic cascade is created. Pions and kaons are focused by 2 magnetic horns.

NOvA

NuMI (Neutrinos at the Main Injector)

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NuMI (Neutrinos at the Main Injector)

π+ -> μ+ + νμ

Neutrinos mostly coming from:

Flux 1-5 GeV 94% νμ 5% νμ 1% νe

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NuMI (Neutrinos at the Main Injector)

π - -> μ- + νμ

Antineutrinos mostly coming from:

Flux 1-5 GeV 7% νμ 92% νμ 1% νe

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Neutrino Oscillation Strategy

Neutrino Production Near detector Far detector

NND = φND σ εND NFD = P φFD σ εFD

(φ: flux, σ: cross-section and ε: acceptance) P: is the oscillation probability

Compare what we expected without oscillation repeat to what we see: the discrepancy comes from the neutrino oscillation

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Blue: νμ Black: ντ Red : νe

Oscillation probability for an initial νμ

https://en.wikipedia.org/wiki/Neutrino_oscillation For NOvA FD, L = 810 km and E ~ 2GeV, L/E ~ 405 km/GeV For NOvA ND, L = 1 km and E ~ 2GeV, L/E ~ 0.5 km/GeV

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FD ND

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FD ND

The ND has ~20K channels The FD has ~344K channels

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Do we have everything?

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Backup

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Neutrinos from the Sun

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For instance:

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How to Make a Conventional Neutrino Beam

Neutrino decay: Main decay to neutrino mode for neutrino beam: From 2 pion body decay: dP/dΩ ??

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How to study oscillation