Olga Botner, Uppsala
Photo: Sven Lidström
Inspirationsdagar, 2015-03-17
OUTLINE
OUTLINE
• WHY NEUTRINO ASTRONOMY?
• WHAT ARE NEUTRINOS?
• A CUBIC KILOMETER DETECTOR
• EXTRATERRESTRIAL NEUTRINOS
• WHAT NEXT?
• CONCLUSIONS
LHC
Neutriner från rymden fångade i Antarktis is / Olga Botner
2015-03-17
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Observation of the Sky, engraving in "Selenografia sive Lunae Descriptio" , Johannes Hevelius 1647
Bibliotheque Nationale de France, Paris, France.
ASTRONOMY WITH PHOTONS
optical astronomy
pioneered by
Ibn al-Haytham
El Basri
(Alhazen)
born c. 965
in present day Iraq
• traditional astronomy relies on capture of light in diverse ranges of the
electromagnetic spectrum … each tells a different story …
?
LHC
OPTICAL
RADIO
INFRARED
X-RAY
Crab nebula: SNR & pulsar (http://chandra.harvard.edu)
Neutriner från rymden fångade i Antarktis is / Olga Botner
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ASTRONOMY WITH PHOTONS
• according to quantum mechanics the basic unit (the quantum) of light is a photon
• at very high energies the universe
is NOT transparent to photons!
• photons interact electromagnetically
‒ in the interior of stars
‒ with starlight
‒ with inter-stellar matter
LHC
‒ with the CMBR
AN ENERGY-DEPENDENT PHOTON HORIZON
Neutriner från rymden fångade i Antarktis is / Olga Botner
2015-03-17
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γ-rays (0.01-1 Mpc)
Neutriner från rymden fångade i Antarktis is / Olga Botner
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ENERGY SCALES OF THE UNIVERSE
1021
ZeV
(Zeta)
???
1018
EeV
(Exa)
Active Galactic Nuclei Gamma Ray Bursts
1015
PeV
(Peta)
1012
109
106
TeV
(Tera)
GeV
(Giga)
MeV
103
KeV
1
eV
(Mega)
(Kilo)
Neutriner från rymden fångade i Antarktis is/ Olga Botner
Supernova
LIMIT OF HUMAN TECHNOLOGY
Current Particle Accelerator
Early accelerators
Lab X-ray
e
Battery
1 volt
Mar 2015
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COSMIC RAYS
the Earth is bombarded by Cosmic Rays – charged particles from outer space
• mostly protons (~90%)
• alphas (He nuclei, ~9%)
• heavier nuclei
LHC
LHC
VISIBLE
CMB
RADIO
RADIO
γ-ray LIMITS
γ RAYS
CRs
M. Turner&T. Ressell, Comments in Astrophys. 14 (1990) 323
Neutriner från rymden fångade i Antarktis is / Olga Botner
discovered by Victor Hess 1912
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COSMIC RAYS
1912: Hess discovers CR
• ascends to 5000 m
• demonstrates that ionization
increases from 1000m up
- not natural radioactivity
• penetrating radiation from space
1938: Pierre Auger
registers ~1015 eV CR in the Alps,
two cloud chambers ~1 km apart
1962: a 1020eV CR registered
Victor Hess, Nobel Prize 1936
Neutriner från rymden fångade i Antarktis is / Olga Botner
Volcano Ranch giant detector array,
New Mexico
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COSMIC RAY SPECTRUM
The highest observed energies in
cosmic rays are
1019 to 3×1020 eV!!
That is 50 Joule!
Same energy as in a tennis ball
hit by e.g. Björn Borg!!
Knee
1 m -2yr -1
a fast serve
68g at 200km/h
~100J
LHC
Ankle
1 km -2yr -1
What is accelerating these
particles????
Neutriner från rymden fångade i Antarktis is / Olga Botner
2015-03-17
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THE WORLDS MOST POWERFUL ACCELERATOR – LHC AT CERN
the Sun accelerates cosmic rays
coronal mass ejection → 1010 eV protons
Neutriner från rymden fångade i Antarktis is / Olga Botner
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THE LARGE HADRON COLLIDER
•
circumference 27 km
•
100 m below the surface
•
super conducting magnets
(8 Tesla)
•
proton beams
•
max energy 7× 1012 eV
per beam
•
moving at 0.999999991
the speed of light at top
energy
Neutriner från rymden fångade i Antarktis is / Olga Botner
LHC
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Energy of an accelerator is proportional to radius times magnetic field
•
What radius is needed to get
3×1020 eV when using LHC
super conducting magnets?
R
P [GeV] = 0.3×B [T] ×R [m]
Neutriner från rymden fångade i Antarktis is / Olga Botner
LHC
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1.3×108 km ~ the Earth distance to the Sun
• Supernova remnants
• Active Galactic Nuclei
• Gamma Ray Bursts
powered by gravitational energy realease
Neutriner från rymden fångade i Antarktis is / Olga Botner
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Cassiopeia A supernova remnant in X-rays
shock fronts
From F. Halzen
acceleration when particles cross high magnetic fields
Possible source of high-energy cosmic rays???
active galaxy
particle flows near
supermassive
black hole
γ-rays (0.01-1 Mpc)
cosmic ray protons
E < 1019 eV
protons with E > 1019 eV interact with
the cosmic microwave background (CMB)
within 30 Mpc
Neutriner från rymden fångade i Antarktis is / Olga Botner
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NEUTRINO – THE IDEAL MESSENGER FROM SPACE
Bruno Pontecorvo
Moisey Markov
M.Markov,1960:
LHC
We propose to install detectors deep in a lake or in the sea and to
determine the direction of charged particles with the help of Cherenkov
radiation.
Neutriner från rymden fångade i Antarktis is / Olga Botner
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WHAT IS A NEUTRINO?
• postulated by Pauli in 1930 to ensure energy conservation in nuclear β decay
Wolfgang Ernst Pauli
(1900 – 1958) was an
Austrian-Swiss physicist,
one of the pioneers of
quantum physics, and
recipient of the Nobel
Prize for Physics in 1945.
“I have done a terrible thing, I have postulated a particle that cannot be detected.”
detecting the ”poltergeist”, 1956
LHC
Frederick
Reines (1918 – 1998),
left, recipient of the Nobel Prize for
Physics in 1995, and Clyde L.
Cowan, Jr. (1919 – 1974)
Neutriner från rymden fångade i Antarktis is / Olga Botner
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WHAT IS A NEUTRINO?
a fundamental matter particle
• electrically uncharged
•”twin” of the electron (and its cousins)
• tiny mass
• travels close to the velocity of light
• interacts only weakly (and gravitationally)
MATTER
ATOM
ELECTRON
NUCLEUS
PROTON
NEUTRON
THE NEUTRINO CAN GO
THROUGH ENORMOUS AMOUNT
OF MATTER WITHOUT BEING
STOPPED.
Neutriner från rymden fångade i Antarktis is / Olga Botner
QUARKS
LHC KINDS OF NEUTRINOS
THREE
• electron neutrino (νe)
• muon neutrino (νµ)
• tau neutrino (ντ)
 electron (e-)
 muon (µ-)
 tau (τ-)
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SOME NEUTRINO NUMBERS
•
every second the Sun emits (2×1038) neutrinos from the nuclear reactions
200.000.000.000.000.000.000.000.000.000.000.000.000
•
→ about 60.000.000.000 neutrinos/cm2/second at Earth
•
in the universe there are 330 million neutrinos per m3 (energy 0.0004 eV)
(but only ~ half a proton per m3 )
•
340 million neutrinos are created in your body every day due to
•
when a Supernova explodes 99% of the energy is
carried away by neutrinos!
•
a solar neutrino will go through many light yearsLHC
of solid lead before it is stopped…..
Neutriner från rymden fångade i Antarktis is / Olga Botner
40K
decays
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SOURCES OF ULTRA HIGH ENERGY
COSMIC RAYS PRODUCE NEUTRINOS!
γ-rays (0.01 – 1 Mpc)
neutrinos
cosmic ray protons
E < 1019 eV
protons with E > 1019 eV interact with
the cosmic microwave background (CMB)
within 30 Mpc
Neutriner från rymden fångade i Antarktis is / Olga Botner
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SEEING THE NEUTRINO
µ
νµ
cascade
shortlived particles
the ν is detected by observing the charged particles
created when it interacts with matter
νµ→ µ
νe → e
Neutriner från rymden fångade i Antarktis is / Olga Botner
ντ → τ
LHC
νx → νx
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CHERENKOV RADIATION
a shock front of Cherenkov light generated when a charged particle
travels faster than light in a medium
(ex. water or ice)
CHERENKOV EFFECT
cos θ =
1
βn
β = vc
n( water ) = 1.33
β =1
θ = 42°
NASA's "Astronomy Picture of the Day" Archive
LHCthe Cherenkov radiation
optical sensors can capture
generated by the muon (electron, tauon) and map it
Neutriner från rymden fångade i Antarktis is / Olga Botner
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NEUTRINO DETECTION
size of detector dependent on
flux and interaction probability
need large detectors:
• the more matter for the ν to interact with,
the more interactions observed with time
typical large tank filled with fluid
Sudbury Neutrino Observatory, Canada
1000t D2O
for detection of solar ν’s (E ~ 107 eV)
number of expected cosmic ν’s (E > 1014 eV)
decreases rapidly with increasing energy
 need HUGE instrumented
volumes (~ 109 t)
LHC
DETECTOR MEDIUM ABUNDANT IN NATURE
Neutriner från rymden fångade i Antarktis is / Olga Botner
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Cherenkov light from a nuclear reactor
Electrons with speeds
to catch
high-energy
higher
than the
speed neutrinos – need lots of material transparent to blue light
of light in the water
create the Cherenkov
in ice, blue light travels 100 – 200 m
light
10-05-28
Science day Malmö
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the icecube project transforms a billion tons of ice into a neutrino detector
125 m
10-05-28
Science day Malmö
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ICECUBE – THE WORLD’S LARGEST NEUTRINO OBSERVATORY
• 5160 DOM’s in ice
• 1km3 = 1 Gt instrumented volume
• started full operations in May 2011
electronics
•
•
20 Mt low-energy ext.
threshold: 10 GeV
PMT
DIGITAL OPTICAL MODULE
Neutriner från rymden fångade i Antarktis is / Olga Botner
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hot water generators
IceCube Site
IceTop tanks
drill tower
5 megawatt hot water drilling system
start 05-06
LHC
•1 million pounds of cargo
• C-130 planes: > 50 flights
Neutriner från rymden fångade i Antarktis is / Olga Botner
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2 days per hole
3.5 cm/second
35
Photo: Mark Krasberg
two DOMs disappearing down the hole
Neutriner från rymden fångade i Antarktis is / Olga Botner
(water level
~
50 m below surface).
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LHC
Neutriner från rymden fångade i Antarktis is / Olga Botner
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Recent results from IceCube / Olga Botner
Jan 2014
1
DATA COLLECTION WITH ICECUBE
•
•
•
•
•
•
events collected since 2005
events selected by triggers
server farm to preprocess & filter data
~ 100 GB/day sent North over satellite
2 WO scientists ensure uptime > 99%
~ 100 TB/y for science
•
•
•
~ 3000 atmospheric µ’s/sec
> 200 upgoing atm. ν’s/day
estimated astrophysical ν’s
Neutriner från rymden fångade i Antarktis is / Olga Botner
 1011/ year
 105 / year
 10-100 / year
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Neutriner från rymden fångade i Antarktis is / Olga Botner
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ICECUBE HIGH ENERGY NEUTRINOS
• two ways to identify high energy neutrinos
LHC
• look for up-going tracks
• Earth is used as a filter
• look for events starting inside IceCube
• detector-based veto
Neutriner från rymden fångade i Antarktis is / Olga Botner
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HIGH-ENERGY NEUTRINO EVENTS
neutrino induced muon entering IceCube from below
LHC
TWO neutrino events starting in IceCube
Neutriner från rymden fångade i Antarktis is / Olga Botner
color code: early times - RED
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LOOKING FOR A NEEDLE IN A HAYSTACK
• for each muon from a neutrino reaction there is ~ a million muons from
cosmic ray reactions in the atmosphere
• these background muons penetrate
through the ice down to the detector
• atmospheric µ rate ~ 103 Hz
• atmospheric ν rate ~ 10-3 Hz
• ASTROPHYSICAL ν rate ~ 10-6 Hz
LHC
REDUCE BACKGROUNDS BY REQUIRING VERY HIGH ENERGY EVENTS!
Neutriner från rymden fångade i Antarktis is / Olga Botner
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BREAKTHROUGH
”Bert”
1.04 PeV
Aug. 2011
–
”Ernie”
1.14 PeV
Jan. 2012
DETECTION OF A FLUX OF ASTROPHYSICAL
ν’S
”Big Bird”
2 PeV
Dec. 2012
• the highest energy ν’s ever observed
• 106 x higher energies than Solar ν’s
• starting event analysis
• dominated by cascades
• ~ 50% atmospheric background
• 28 events/2 yrs (2013)
• 54 events/4 yrs (2014)
• isotropic directions, probably from many extragalactic sources
Neutriner från rymden fångade i Antarktis is / Olga Botner
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ASTROPHYSICAL ν’S
CONFIRMATION!
flux of muon neutrinos
through the Earth
neutrinos of all flavors
interacting inside
IceCube
Neutriner från rymden fångade i Antarktis is / Olga Botner
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HIGH ENERGY STARTING EVENTS SKYMAP compatible with isotropy
• too few events to identify sources
shower events only
p-value = 7.2 %
[IceCube PRL 113 (2014)]
~ 40% of the events are expected to originate in the atmosphere (bckg)
Neutriner från rymden fångade i Antarktis is / Olga Botner
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LHC
[Slide: Markus Ahlers NeuTel2015]
Neutriner från rymden fångade i Antarktis is / Olga Botner
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NEUTRINO STARS?
• to look for neutrino ”stars” need more events
• search for clustering
• decrease the energy threshold
atmospheric ν’s
dominate
atmospheric µ’s
dominate
LHC
equatorial skymap ~40 000 events [Astrophys.J. 732 (2011) 18]
Neutriner från rymden fångade i Antarktis is / Olga Botner
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FUTURE –ICECUBE-GEN2 – HIGH-ENERGY
ALTERNATIVE – BUILD A LARGER DETECTOR
Opening the Southern sky with a surface veto!
Neutriner från rymden fångade i Antarktis is / Olga Botner
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OUTLINE
CONCLUSIONS
• a new window to the universe has been
cracked open
• IceCube has observed a flux of neutrinos
from cosmos
• but where are the ”neutrino stars”?
• need more data at high energy
• Sweden is at the forefront of this research
LHC
Neutriner från rymden fångade i Antarktis is / Olga Botner
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