NEUTRINOS AND DARK MATTER
- GREAT INQUIRIES OF THE 21 ST CENTURY
Barbara Szczerbinska
Dakota State University
Center for Theoretical Underground Physics
Conference for Undergraduate Women in Physics - BHSU - 2016
UNIVERSE
LAW SCHOOL – HERE I COME
UNIVERSITY OF BRESLAU, POLAND
UNIVERSITY OF SOUTH CAROLINA, SC
UNIVERSE - STATISTICS
•
Etymology – Latin Universum (Unvorsum): un, uni – one, vorsum, versum – something
rotated, changed; everything rotated as one or everything rotated by one
•
Age – 13.8 billion years
•
Size – observable universe – radius ~46 billion light years (diameter of typical galaxy –
30,000 light years, distance between galaxies – 3 million light years; Milky Way Galaxy~
100,000 light years in diameter, Andromeda Galaxy ~ 2.5 million light years away)
•
Components – stars, planets, galaxies, intergalactic space, subatomic particles, matter,
energy
•
More than 100 billion galaxies in observable Universe
•
Typical galaxies range from dwarfs (10 million = 10^7 stars)
to giants (1 trillion stars = 10^12)
•
Estimated number of stars in the
observable Universe
300 sextillion = 3*10^23
Light-year (ly) = 9.5 trillion km = 5.9 trillion miles
THE UNIVERSE ACCORDING TO THE ANCIENT GREEKS
FOUR ELEMENTS
Earth
Fire
Water
Air
WHAT IS THE UNIVERSE MADE OFF?
WHAT IS THE UNIVERSE MADE OFF?
WHAT IS THE UNIVERSE MADE OFF?
WHAT IS THE UNIVERSE MADE OFF?
Leptons
12
WHAT IS THE UNIVERSE MADE OFF?
WHAT IS THE UNIVERSE MADE OFF?
NEUTRINOS – SMALL BUT ABUNDANT
• All objects around us are made out of atoms (nucleons, electrons)
but
• Neutrinos and photons are most abundant particles in the universe!!!
• For each nucleon there are ~1,000,000,000 neutrinos
but
• They are extremely difficult to study and we still don’t know everything about them
and
• A good understanding of neutrinos is key in understanding the universe
A BRIEF HISTORY OF NEUTRINOS
• Before 1930’s – continuous energy spectrum of beta decay
– validated conservation of energy???
G. J. Neary, Roy. Phys. Soc., A175, 71 (1940).
A BRIEF HISTORY OF NEUTRINOS
• Before 1930’s – continuous energy spectrum of beta decay
– validated conservation of energy???
G. J. Neary, Roy. Phys. Soc., A175, 71 (1940).
1930 - WOLFGANG PAULI
Zürich, Dec. 4, 1930
Physics Institute of the ETH, Gloriastrasse, Zürich
Dear Radioactive Ladies and Gentlemen,
As the bearer of these lines, to whom I graciously ask you to listen, will explain to you in more detail,
because of the "wrong" statistics of the N- and Li-6 nuclei and the continuous beta spectrum, I have hit
upon a desperate remedy to save the "exchange theorem" (1) of statistics and the law of conservation of
energy. Namely, the possibility that in the nuclei there could exist electrically neutral particles,
which I will call neutrons, that have spin 1/2 and obey the exclusion principle and that further
differ from light quanta in that they do not travel with the velocity of light. The mass of the
neutrons should be of the same order of magnitude as the electron mass and in any event not
larger than 0.01 proton mass. The continuous beta spectrum would then make sense with the
assumption that in beta decay, in addition to the electron, a neutron is emitted such that the sum of the
energies of neutron and electron is constant. …
I admit that my remedy may seem almost improbable because one probably would have seen those
neutrons, if they exist, for a long time. But nothing ventured, nothing gained, and the seriousness of the
situation, due to the continuous structure of the beta spectrum, is illuminated by a remark of my honored
predecessor, Mr Debye, who told me recently in Bruxelles: "Oh, It's better not to think about this at all,
like new taxes." Therefore one should seriously discuss every way of rescue. Thus, dear radioactive
people, scrutinize and judge. - Unfortunately, I cannot personally appear in Tübingen since I am
indispensable here in Zürich because of a ball on the night from December 6 to 7. With my best regards
to you, and also to Mr. Back, your humble servant.
W. Pauli
18
A BRIEF HISTORY OF NEUTRINOS
• Before 1930’s – continuous energy spectrum of beta decay
– validated conservation of energy???
G. J. Neary, Roy. Phys. Soc., A175, 71 (1940).
•
1932 – James Chadwick discovers the neutron – too heavy to be Pauli’s
particle
•
1933 – Enrico Fermi proposes "neutrino"
as the name for Pauli's postulated particle
•
>1933 – development of the theory of weak interactions and beta decay
•
1956 – Frederick Reines and Clyde Cowan, report the first evidence for
neutrinos (nuclear reactor antineutrinos: νe + p+ → n + e+)
•
1962 - a group of scientists from Columbia University and Brookhaven
National Laboratory perform the first accelerator neutrino experiment and
demonstrate the existence of two species of neutrinos, the electron and
muon neutrino
•
1967 – Ray Davis & John Bahcall first
solar experiment at Homestake Mine
•
2000 – DONUT (E872) experiment finds evidence for the 3 rd neutrino
NEUTRINOS - PARTICLES OF 21ST CENTURY
NEUTRINO MIXING AND OSCILLATIONS
• 1957, 1967 – Bruno Pontecorvo proposes
that neutrinos could oscillate
• The particles interact according to their flavor
• The particles travel according to their mass
• Flavor state  Mass state
1998 – the first evidence for neutrino oscillation from Super-K
2001 - the first scientific results of SNO were published
3  CASE
=U

All of these numbers are in the 3
neutrino paradigm

In other words, they were calculated
using formulae assuming that there
are 3 and only 3 neutrinos, and that
they interact normally

If this isn’t true, the numbers may be
wrong or meaningless, or just
approximations

One way to test the paradigm, is to
measure the numbers different ways
PDG 2015 [2013]
sin2(2θ12) = 0.846  0.021 [0.024]
Δm221 = 7.53  0.18 [0.20]  10-5 eV2
sin2(2θ23) = 0.999 +0.001 -0.018 [0.05]
Δm322 = 2.44  0.06 [0.12]  10-3 eV2
sin2(2θ13) = 0.093  0.008 [0.013]
PHYSICS CHALLENGES
THE NOBEL PRIZE IN PHYSICS 2015
Takaaki Kajita
Arthur B. McDonald
Super-Kamiokande Collaboration
University of Tokyo, Kashiwa, Japan
SNO Collaboration
Queen’s University, Kingston, Canada
“ for the discovery of neutrino oscillations,
which shows that neutrinos have mass”
NOBEL PRIZES FOR NEUTRINO RESEARCH
1988 - Leon Max Lederman, Melvin Schwartz, Jack Steinberger
- "for the neutrino beam method and the demonstration of the
doublet structure of the leptons through the discovery of the muon
neutrino “
1995 - Frederick Reines - "for the detection of the neutrino" and "for
pioneering experimental contributions to lepton physics“
2002 - Ray Davis, Masatoshi Koshiba
R - "for the detection of the
neutrino" and "for pioneering experimental contributions to lepton
physics“
WHY NEUTRINOS ARE IMPORTANT?
• Neutrinos carry potential answer to matter-antimatter asymmetries
• The weak force that neutrinos feel is what changes protons to neutrons,
powering nuclear fusion reactions in the sun and other stars, and creating the
elements that make planets and life itself possible.
• Neutrinos emitted in the first few seconds of a core-collapse supernova carry
with them the potential for great insight into the evolution of the universe
• Neutrinos are the only component of dark matter that we understand, and
figuring out the rest will help us understand the structure and evolution of the
universe.
• Neutrino detectors, could tell us if a purported nuclear reactor is on, what its
power level is and even if it is producing plutonium. This may have some real world applications.
•
Do neutrino oscillations violate CP?
???
•
CP violation drive a matter-antimatter asymmetry (leptogenesis)?
•
What is the value of the CP violating phase ?
•
CP violation among neutrinos related to CP violation in the quark sector?
•
What are the relative masses of the three known neutrinos?
•
Are they “normal,” (m3>m2>m1) or “inverted” hierarchy (m2>m1>m3)?
•
•
•
•
The ordering has important consequences for interpreting the results of neutrinoless double beta decay
•
origin and pattern of masses in a more fundamental way
Is θ23 maximal (45o)?
•
Will the pattern of neutrino mixing provide insights regarding unification of the fundamental forces?
•
Will it indicate new symmetries or new selection rules?
Are neutrinos their own antiparticles?
•
lepton number violation, or leptogenesis, in the early universe?
•
Observable : neutrinoless double beta decay in nuclei
What can we learn from supernovae neutrinos?
•
Can we observe the neutrino remnants of all supernovae that
have occurred since the beginning of time?
•
What can neutrinos tell us about new physics? beyond the Standard Model, dark energy, extra dimensions?
Do sterile neutrinos exist?
ELBNF – EXPERIMENT AT LONG-BASELINE NEUTRINO
FACILITY






LBNE
Target
Tevatron
Main
Injector
 LBNE -> LBNF -> ELBNF -> DUNE
 Homestake Mine -> DUSEL -> SUSEL -> Sanford Lab -> SURF
BEAM-ON-A-HILL
Novel beam-on-a-hill construction for 2.3 MW from 60-120GeV protons
THE OTHER END OF THE BEAM - SURF
LIQUID ARGONNE DETECTOR
Volume: 15m x 23m x 62m x 2
Total Liquid Argon Mass:
~50,000 tonnes
PROTON DECAY
 LAr TPC high efficiency/low background for kaon modes
 Essential if signal is in lifetime sensitivity range
ATMOSPHERIC NEUTRINOS
SUPERNOVA 
• When a star's core collapses ~99% of
the gravitational binding energy of
the proto-neutron star goes into ν's
• SN at galactic core (10 kpc)
 tens of thousands of interactions
in 20 kt LArTPC in tens of seconds
• Liquid Argon sees , Water anti.
WHAT IS THE UNIVERSE MADE OFF?
WHAT IS THE UNIVERSE MADE OFF?
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ORDINARY BARYONIC MATTER
• Galaxies, stars, planets, asteroids, living and nonliving things on Earth
• Composed of atoms (electrons, protons, neutrons)
• Absorbs and emits light
• Accounts for ~4% of the Universe
WHAT IS THE REMAINING 96% OF THE UNIVERSE?
• Dark Energy:
•
Universe is expanding from the time of Bing Bang
•
Will it keep expanding??? (depends on the gravity which depends on the mass of the
universe)
•
Critical mass density of the universe 10^(-29)g/cm^3
•
Three possible types of universe:
o Closed universe – universe will expend, slow, stop and collapse
o Critical/flat universe – will expand but expansion will become slower and slower – all
becomes cold
o Open universe – universe keeps expanding at constant rate
•
Current expansion rate is accelerating
•
Fourth option of the universe – accelerating universe
•
Cause of acceleration – unknown – but called Dark Energy
• Dark Matter:
•
Does not absorb or emit light or other forms of electromagnetic energy
•
Dark Matter particles are affected by gravitational force
•
Accounts for 23% of the Universe
FRITZ ZWICKY – GENIUS AND CURMUDGEON
Looking at the clusters of orbiting galaxies determined that 80-90% of mass is missing
VERA RUBIN – PROVED THE EXISTENCE OF
DARK MATTER
• Vassar, Cornell (1951), Georgetown (1954)
• National Medal of Science
EVIDENCE OF DARK MATTER EXISTENCE
•
Evidence I
•
Gravitational force = centripetal force
𝑀∗𝐺
𝑣2 =
𝑟
•
Visible mass more concentrated at the
center of the galaxy
•
Expectation: starts near the galaxy’s
center move faster than at the edges
•
Observation: all stars have the same
rotational speed regardless the location
Andromeda Galaxy
EVIDENCE OF DARK MATTER EXISTENCE
•
Evidence I
Conclusion: there must be some
invisible mass (Dark Matter)
responsible for the observed
gravitational effect
Andromeda Galaxy
EVIDENCE OF DARK MATTER EXISTENCE
• Evidence II:
• The hot gases in
galactic clusters not
enough to account
for the ‘missing mass’
• 5-6 times more mass
than ordinary mass to
prevent the hot gas
from escaping
The Coma Cluster of Galaxies
EVIDENCE OF DARK MATTER EXISTENCE
•
Evidence III:
Gravitational lensing and Einstein Rings
"The hardest thing in
the world to understand
is the income tax."
EVIDENCE OF DARK MATTER EXISTENCE
•
Evidence III:
Gravitational lensing and Einstein Rings
DM
EVIDENCE OF DARK MATTER EXISTENCE
•
Evidence III:
Gravitational lensing and Einstein Rings
DM
EVIDENCE OF DARK MATTER EXISTENCE
•
Evidence III:
Gravitational lensing and Einstein Rings
DM
EVIDENCE OF DARK MATTER EXISTENCE
•
Evidence III:
Gravitational lensing and Einstein Rings
DM
EVIDENCE OF DARK MATTER EXISTENCE
•
Evidence III:
Gravitational lensing and Einstein Rings
WHAT IS DARK MATTER MADE OF?
• Cold gas between the stars?
WHAT IS DARK MATTER MADE OF?
• Cold gas between the stars? X
• Black holes?
WHAT IS DARK MATTER MADE OF?
•
Cold gas between the stars? X
•
Black holes? X
•
MACHOs – Massive Compact Halo Objects
• Large objects
• Baryonic matter
• Located at galaxies halos
• Low luminosity
• Brown and white dwarfs, neutron stars, black
holes
Once you eliminate the impossible, whatever
remains, no matter how improbable, must be the
truth.
Arthur Conan Doyle
WHAT IS DARK MATTER MADE OF?
• WIMPs – Weakly Interacting Massive Particles
• Very massive
• Neutral particles
• Weakly interact with ordinary matter
• Difficult to detect
• Large Hadron Collider – produce particles
which could decay into WIMPs
HOW DO WE SEARCH FOR DARK MATTER?
SERIOUSLY - HOW DO WE SEARCH OR DARK MATTER?
• indirect detection experiments, which look for the
products of WIMP annihilations
• direct detection experiments, which search for the
scattering of dark matter particles off atomic nuclei
within a detector
INDIRECT DETECTION
• Indirect detection experiments search for the products of WIMP annihilation
or decay
• If WIMPs are Majorana particles (WIMPs are their own antiparticle) then two
WIMPs could annihilate to produce gamma rays or Standard Model particle antiparticle pairs
• Detectors – telescopes: PAMELA, FERMI Gamma-ray Space Telescope,
IceCube, AMANDA, ANTARES
63
DIRECT DETECTION
• Direct detection experiments typically operate in deep underground
laboratories to reduce the background from cosmic rays.
• Underground laboratories:
• the Soudan mine;
• the SNOLAB underground laboratory at Sudbury, Ontario (Canada);
• the Gran Sasso National Laboratory (Italy);
• the Canfranc Underground Laboratory (Spain);
• the Boulby Underground Laboratory (UK);
• the Sanford Underground Research Facility, South Dakota (US).
DIRECT DETECTION - DETECTORS
•
Cryogenic detectors, operating at temperatures below 100mK, detect the heat produced
when a particle hits an atom in a crystal absorber such as germanium.
•
Noble liquid detectors detect the flash of scintillation light produced by a particle
collision in liquid xenon or argon.
•
Cryogenic detector experiments include: CDMS, CRESST, EDELWEISS, EURECA.
•
Noble liquid experiments include ZEPLIN, XENON, DEAP, ArDM, WARP, DarkSide and
LUX, the Large Underground Xenon Detector
•
Both of these detector techniques are capable of distinguishing background particles
which scatter off electrons, from dark matter particles which scatter off nuclei.
65
WHERE DO WE TEST IT ALL?
66
THE MOST ASTOUNDING FACT
https://vimeo.com/38101676