Transcript UCLA Symposium F 2 C@80 Nov. 2009 16 - LIGO | Hanford

Searching for gravitational waves
with lasers
Rick Savage
Caltech
LIGO Hanford Observatory - Richland, WA
Black holes and time warps



Sept 1974 - transferred to UCLA in Physics
Jan 1975 - started working for F. Chen and N.
Luhmann as undergraduate lab assistant (with Doug
Cook)
1976 to1986 - plasma diagnostics with N. Luhmann,
T. Peebles, H. Fetterman, et al.

1986 to 1992 - graduate school in EE at UCLA with
Chan Josh, Warren Mori, Ken Marsh, Chris Clayton, et al.
» Masters thesis – Degenerate four-wave mixing in heated CO2 gas
» PhD thesis – Frequency upshifting of electromagnetic radiation via
an underdense relativistic ionization front

1992 to present - LIGO project at Caltech until 1997
then LIGO Hanford Observatory in Richland, WA
LIGO-G0901004
UCLA Symposium F2C@80 Nov. 2009
2
LIGO: Laser Interferometer Gravitationalwave Observatory
Hanford, WA
• Managed
and operated by
Caltech & MIT with funding
from NSF
• Goal: Direct observation of
gravitational waves
MIT
Caltech
Livingston, LA
•Open an new observational
window on the Universe
LIGO-G0901004
3
LIGO Scientific Collaboration
LIGO-G0901004
UCLA Symposium F2C@80 Nov. 2009
4
General relativity – gravitational waves
“Matter tells spacetime how to curve.
Spacetime tell matter how to move.”
J. A Wheeler
Albert Einstein
1916
GW: oscillating
quadrupolar strain
LaserinInterferometer
spacetime
LIGO-G0901004
UCLA Symposium F2C@80 Nov. 2009
5
Potential sources
Coalescing
Binary Systems
‘Bursts’
• Neutron stars, low
mass black holes,
and NS/BS systems
galactic asymmetric
core collapse
supernovae
cosmic strings
???
Credit: AEI, CCT, LSU
Credit: Chandra X-ray Observatory
Cosmic GW
background
stochastic,
incoherent
background
Continuous Sources
Spinning neutron stars
probe crustal deformations
Casey Reed, Penn State
LIGO-G0901004
NASA/WMAP Science Team
UCLA Symposium F2C@80 Nov. 2009
6
Capturing the waveform
Sketch:
Kip Thorne
LIGO-G0901004
UCLA Symposium F2C@80 Nov. 2009
7
Detection of gravitational waves
Michelson interferometer
- differential length change
sensor
LIGO-G0901004
UCLA Symposium F2C@80 Nov. 2009
8
Ligo detectors
Power Recycled
Michelson
Interferometer
with Fabry-Perot
Arm Cavities
4 km-long
Fabry-Perot
arm cavity
recycling
mirror
test masses
Laser
signal
LIGO-G0901004
beam splitter
UCLA Symposium F2C@80 Nov. 2009
9
Beam tubes and chambers
Beam tubes:
• 1.2 m diameter
• LN2 pumps at ends
• P < 1e-09 torr
• dominated by H2
LIGO-G0901004
UCLA Symposium F2C@80 Nov. 2009
10
Isolated environment for test masses
LIGO-G0901004
UCLA Symposium F2C@80 Nov. 2009
11
Suspended test masses
LIGO-G0901004
UCLA Symposium F2C@80 Nov. 2009
12
Initial LIGO displacement sensitivity
Antenna patterns
+
pol
G
pol
NS-NS binary inspiral range ~ 15 Mpc (S/N = 8)
S5 science
run
Nov. `05
to
Oct `07
avg
LIGO-G0901004
UCLA Symposium F2C@80 Nov. 2009
13
Scientific results of S5 run


No detections (so far) - data still being analyzed
Astrophysical results – upper limits
“If LIGO didn’t detect it, then it can’t be bigger than …”
» CRAB pulsar – “no more than 4 percent
of the energy loss of the pulsar is caused
by the emission of gravitational waves.”
(ApJL 683, L45)
» Gamma ray burst GRB 070201 –
LIGO “results give an independent way
to reject hypothesis of a compact binary
progenitor in M31”
(ApJ 2008, 681, 1419)
» Upper limit on the stochastic gravitational
wave background
(http://www.nature.com/nature/journal/
v460/n7258/pdf/nature08278.pdf)
LIGO-G0901004
UCLA Symposium F2C@80 Nov. 2009
Credits for X-ray Image:
NASA/CXC/ASU/J. Hester et al.
Credits for Optical Image:
NASA/HST/ASU/J. Hester et al.
14
What’s next? Advanced Ligo.



Quantum noise
limited
interferometer
Factor of 10
increase in
sensitivity
Factor of 1000
increase in
event rate
LIGO-G0901004
UCLA Symposium F2C@80 Nov. 2009
15
Laser source: 10 W to 200 W
Diode-pumped
YAG lasers
LIGO-G0901004
UCLA Symposium F2C@80 Nov. 2009
16
Vibration isolation: passive to active
• Masses and
damped springs
LIGO-G0901004
• Geophones and accelerometers on payload
• Active feedback control – 6 deg. of freedom
UCLA Symposium F2C@80 Nov. 2009
17
Test mass suspensions
• Single pendulum
• Quadruple pendulum
with reaction masses
• 40 kg test masses
LIGO-G0901004
UCLA Symposium F2C@80 Nov. 2009
18
Time warp – 1763 Boelter Hall
LIGO-G0901004
UCLA Symposium F2C@80 Nov. 2009
19
To Frank ……. thank you.
LIGO-G0901004
UCLA Symposium F2C@80 Nov. 2009
20