HEPAP Subpanel

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Imagining the Future Gravitational Wave
Astronomy
Barry Barish Caltech 28-Oct-04
What infrastructure will contribute to
facilitating broad participation, community
growth, and the best possible science?
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A Roadmap for the Future
A "roadmap" is an extended look at the future of
a chosen field of inquiry composed from the
collective knowledge and imagination of the
brightest drivers of change in that field. R
Galvin Motorola
Frontier Pathway Scenic and Historic Byway
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Creating a Roadmap for the Future Gravitational
Wave Astronomy

• What have we accomplished?
• Where are we now?
• Where are we going?
• What are the paths to get there?
• What tools do we need to reach our goals?

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Comparing the Evolutionof Two Fields
Neutrino Physics and Astronomy
Gravitational Wave Astronomy
Solar Neutrinos
Binary Black Hole Merger
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Neutrinos the birth of the idea
1930
Pauli's letter of the 4th of December 1930 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, how because of the "wrong" statistics of
the N and Li6 nuclei and the continuous beta
spectrum, I have hit upon a deseperate remedy to
save the "exchange theorem" of statistics and the
law of conservation of energy. Namely, the
possibility that there could exist in the nuclei
electrically neutral particles, that I wish to
call neutrons, which have spin 1/2 and obey the
exclusion principle and which 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 massesgt The continuous beta spectrum
would then become understandable by the
assumption that in beta decay a neutron is
emitted in addition to the electron such that the
sum of the energies of the neutron and the
electron is constant... I agree that my
remedy could seem incredible because one should
have seen those neutrons very earlier if they
really exist. But only the one who dare can win
and the difficult situation, due to the
continuous structure of the beta spectrum, is
lighted by a remark of my honoured predecessor,
Mr Debye, who told me recently in Bruxelles "Oh,
It's well better not to think to this at all,
like new taxes". From now on, every solution to
the issue must be discussed. Thus, dear
radioactive people, look and judge. Unfortunately,
I cannot appear in Tubingen personally since I
am indispensable here in Zurich because of a ball
on the night of 6/7 December. With my best
regards to you, and also to Mr Back. Your humble
servant . W. Pauli
Wolfgang Pauli
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Neutrinos a glitch
1932
Chadwick discovered the neutron, but neutrons are
heavy and do not correspond to the particle
imagined by Pauli.
Pauli responds .
J Chadwick
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Neutrinos
1933
Pauli responds at Solvang, in October 1933 ...
their mass can not be very much more than the
electron mass. In order to distinguish them from
heavy neutrons, mister Fermi has proposed to name
them "neutrinos". It is possible that the proper
mass of neutrinos be zero... It seems to me
plausible that neutrinos have a spin 1/2... We
know nothing about the interaction of neutrinos
with the other particles of matter and with
photons the hypothesis that they have a magnetic
moment seems to me not founded at all."
E Fermi
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Gravitational Waves the birth of the idea
1916
Newtons Theory instantaneous action at a
distance
Einsteins Theory information carried by
gravitational radiation at the speed of light
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Gravitational Wavesa glitch
Early claims of gravitational wave detection were
not confirmed.
J. Weber
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Developing the Theoryrefining the predictions

• "Since I first embarked on my study of general
  relativity, gravitational collapse has been for
  me the most compelling implication of the theory
  - indeed the most compelling idea in all of
  physics . . . It teaches us that space can be
  crumpled like a piece of paper into an
  infinitesimal dot, that time can be extinguished
  like a blown-out flame, and that the laws of
  physics that we regard as 'sacred,' as immutable,
  are anything but.
• John A. Wheeler in Geons, Black Holes and
  Quantum Foam

John Wheeler
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Neutrinos direct detection
1953
Reines and Cowan The target is made of about 400
liters of water mixed with cadmium chloride The
anti-neutrino coming from the nuclear reactor
interacts with a proton of the target, giving a
positron and a neutron. The positron annihilates
with an electron of target and gives two
simultaneous photons. The neutron slows down
before being eventually captured by a cadmium
nucleus, that gives the emission of photons about
one 15 microseconds after those of the positron.
All those photons are detected and the 15
microseconds identify the "neutrino" interaction.

Fred Reines
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Indirectevidence for gravitational waves
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Direct Detectionstill waiting ..
Gravitational Wave Astrophysical Source
Terrestrial detectors LIGO, TAMA, Virgo, AIGO
Detectors in space LISA
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The Birth of a Field

• The evolving roadmap for neutrino physics

astrophysics
particle physics
? properties
? beams
? interactions
Reines-Cowan direct n detection
15
The Birth of a Field

• The evolving roadmap for gravitational-wave
  astrophysics

astrophysics
physics
Improved Sensitivity
GW Properties
GW Observed
LIGO et al (soon ??) direct grav. wave detection
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Neutrinos the properties
1960
In 1960, Lee and Yang are realized that if a
reaction like ?- ? e- ? ? is not observed,
this is because two types of neutrinos exist nm
and ne
Lee and Yang
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Neutrinos Beams
1960
Mel Schwartz realized the possibility to produce
an intense neutrino beam from the decay of pions,
that are particles produced from the collision of
a proton beam produced in accelerators P N ?
Nucleons n?s ?? ? ? ? ?
Mel Schwartz
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Two Neutrinos
1962
AGS Proton Beam
Schwartz Lederman Steinberger
Neutrinos from m-decay only produce muons (not
electrons) when they interact in matter

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Neutrinos the modern era
1970s
High energy neutrino beams at CERN and Fermilab
15 foot Bubble Chamber At Fermilab
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Neutrino Physics weak neutral current
Gargamelle Bubble Chamber CERN
First evidence for weak neutral current nm e
? nm e
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Neutrino Physics neutrino scattering
CCFR Fermilab nm N ? m X

• Quark Structure
• QCD

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Neutrino Astrophysics solar neutrinos
Ray Davis
Homestake Detector

• Solar Neutrino Detection
• 600 tons of chlorine.
• Detected neutrinos of energy gt 1 MeV
• Detection verifies fusion process in the sun
• The rate of solar neutrinos detected is three
  times less than predicted

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The Development of the Field

• The evolving roadmap for neutrino physics

weak neutral current quark structure QCD
astrophysics
particle physics
solar ns
? properties
? beams
nm ne
Schwartz-BNL HE CERN/Fermilab
? interactions
Reines-Cowan direct n detection
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Properties of Gravitational Waves
The Speed
If gamma ray burst (GRB) and gravitational waves
arrive at same time to within 1 sec Then,
speeds are the same to 1 second / 2 billion yrs

1 part in 1017
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Properties of Gravitational Waves
The Polarization of Gravitational Waves
TAMA 300
LIGO
GEO 600
Virgo
LIGO
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Advanced LIGOimproved subsystems
Multiple Suspensions
Sapphire Optics

• Active Seismic

Higher Power Laser
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Advanced LIGOCubic Law for Window on the
Universe
Improve amplitude sensitivity by a factor of
10x number of sources goes up 1000x!
Virgo cluster
Advanced LIGO
Initial LIGO
Today
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Event Localization With a Network
cosq dt / (c D12) Dq 0.5 deg
DL dt/c
q
1
2
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Advanced LIGO
2007

• Enhanced Systems
• laser
• suspension
• seismic isolation
• test mass

Rate Improvement 104
narrow band optical configuration
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The Development of a Field

• The evolving roadmap for gravitational-wave
  astrophysics

astrophysics
physics
Strong Field GR
Binary Inspiral Pulsars
Improved Sensitivity
GW Properties
GW Networks Adv Detectors
Speed Polarization
GW Observed
LIGO et al (soon ??) direct grav. wave detection
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n Oscillation Probability
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n Oscillation Phenomena
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The Status of the Field

• The evolving roadmap for neutrino physics

weak neutral current quark structure QCD
astrophysics
particle physics
solar ns rate?
? properties
? beams
nm ne 3 n types n oscillations
Schwartz-BNL HE CERN/Fermilab
? interactions
Reines-Cowan direct n detection
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Roadmap for the Futureof Two Fields
Neutrino Physics and Astronomy
Gravitational Wave Astronomy
High Energy Neutrino Astonomy
LISA Low Frequency Grav Waves
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Goals Dirac or Majorana particle?
Majorana The neutrino is its own antiparticle
Ettore Majorana
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Acceleratorsneutrino factory neutrinos from
muon collider
muon collider
Example 7400 km baseline Fermilab ? Gran
Sasso world project
neutrino beams select nms or anti nms
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Future Long Term Goals for the Field

• The future roadmap for neutrino physics

astrophysics
particle physics
? properties
? beams
Dirac vs Majorana
Superbeams
n osc parameters CP violation
Neutrino Factories
? interactions
the long term
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Future Long Term Goals for the Field

• The future roadmap for neutrino physics

astrophysics
particle physics
WIMP Dark matter
High energy Solar Supernovae GRBs
? properties
? beams
Dirac vs Majorana
cosmic rays
n osc parameters
? interactions
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Future Long term Goals for the Field

• The evolving roadmap for gravitational-wave
  astrophysics

astrophysics
physics
New Physics
New Phenomena
Improved Sensitivity
GW Properties
Speed Polarization
?????????
GW Observed
LIGO et al (soon ??) direct grav. wave detection
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Multi-messenger Astronomy supernova
gravitational waves
neutrinos
electromagnetic radiation
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Emerging Detector Technologies

• Cryogenic suspensions (LCGT Japan)
• Broadband (white light) interferometers
  (Hannover, UF)
• All-reflective interferometers (Stanford)
• Reshaped laser beam profiles (Caltech)
• Quantum non-demolition
• Evade measurement back-action by measuring of an
  observable that does not effect a later
  measurement
• Speed meters (Caltech, Moscow, ANU)
• Optical bars (Moscow)
• Correlations between the SN and RPN quadratures

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Sub-quantum-limited interferometer
Quantum correlations(Buonanno and Chen)
Input squeezing
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Ultimate Goal for the Field

• The future roadmap for neutrino physics

QCD WIMPS
astrophysics
particle physics
High energy Solar Supernovae GRBs
? properties
? beams
Dirac vs Majorana
n osc parameters
relic ns
? interactions
? cosmology
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Ultimate Goal for the Field

• The evolving roadmap for gravitational-wave
  astrophysics

astrophysics
physics
New Physics
New Phenomena
Improved Sensitivity
GW Properties
Speed Polarization
?????????
GW Observed
gw cosmology
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Neutrino Signals from the Early Universe
the ultimate goal
Cosmic microwave background

• Neutrinos decoupled just prior to big bang
  nucleosynthesis, when the age of the universe was
  around 1s and the temperature around 1 MeV.
• Their momentum distribution subsequently
  redshifted to an effective temperature Tn 1.9
  K, and they have an average density of 300/cm3.
  
• The direct detection of such low-energy
  neutrinos remains an ultimate challenge.

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Gravitational Waves from the Early Universe
the ultimate goal
Cosmic microwave background
Maybe a Special New Experimant A. Vecchio
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Ultimate GW Stochastic Probes
log Omega(f) -11 -12 -13 -14
-15 -16
3rd generation sensitivity limit (1yr)
?
WD-WD
NS-NS
CLEAN
LISA sensitivity limit (1yr)
NS
BH-MBH
CORRUPTED
-6 -5 -4 -3 -2
-1 0 1 2 3 log f
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Future experiments in the gap (?)
A. Vecchio
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Imagining the Future Reaching our Goals
The morale of my story Comparing roadmaps
for neutrinos gravitational waves
The key to the future will be investing enough
resources in technological development and new
detectors