Transcript Li-Baker HFGW Detector Fabrication

Li-Baker HFGW Detector
Fabrication
Plans and Specifications
Development
PROPOSAL DETAILS
• Proposals submitted to US National Science
Foundation and various P. C. China
Foundations.
• Cost of initial effort approximately: $653,000 US
or 4.4 million Yuan.
• Final Cost: approximately 6 Million US or 41
Million Yuan.
• Initial Phase (Plans and Specifications): 2010
Completion of Detector Fabrication: 2012.
The Proposal
Development of the
Li-Baker ultra-high sensitivity high
frequency relic gravitational wave
detector
Principal Investigator: Fangyu Li.
Senior Investigator: Zhenyun Fang
Chongqing University PR China
Principal Investigator: R.C. Woods, ECE Department, Louisiana State University
Senior personnel: R. M L Baker, Jr., and
G.V. Stephenson, Transportation Sciences Corporation, California USA
Classes of GW Detectors
• Mass Resonance, e.g., “Weber Bar” (Low
Frequency: fractions of a Hertz to a few kHz)
• Interferometric, e.g., LIGO, Virgo, GEO600,
LISA, etc., (Also Low Frequency – looking for
Black Hole Coalescence)
• Energy Resonance: Based on Professor Li’
1992 Theories (High Frequency: Definition: 100
kHz, GHz and Higher – looking for Relic GWs)
Summary
The aim of the proposed development is to establish support for a high
frequency relic gravitational wave (HFRGW) detection system to be
developed by Louisiana State University (LSU) and the Gravwave division
of Transportation Sciences Corporation (TSC) in the U.S.A. and
Chongqing University, P. R. China
This Li-Baker HFGW detector would serve to broaden the search spectrum of
the existing LIGO low frequency gravitational wave detection system.
The outcome of the initial study will be an engineering-ready design for a relic
HFGW detection system as described in the sections below.
Following submission of a subsequent proposal, this design will be
implemented with additional funding in the 2011 – 2012 time-frame. This
experimental facility will achieve ultra-high sensitivity detection of
gravitational waves over a completely new frequency band (near
the cutoff of what is cosmically generated, in the 3 to 10GHz range).
Brief History
High Frequency Gravitational Waves (HFGWs) are gravitational waves that
have frequencies greater than 100kHz, following the definition of Douglass and
Braginsky (1979).
The first mention of HFGWs was during a lecture by Forward and Baker
(1961). The lecture was based upon a paper concerning the dynamics of gravity
(Klemperer and Baker, 1957) and Forward’s prior work on the Weber Bar. The first
publication concerning HFGWs was in 1962 when Gertsenshtein (1962) authored his
pioneering paper entitled “Wave resonance of light and gravitational waves”. Next, L.
Halpern and B. Laurent (1964) suggested that “at some earlier stage of development
of the universe (the big bang) conditions were suitable to produce strong (relic)
gravitational radiation.” They then discussed “short wavelength” or HFGWs. In 1968
Richard A. Isaacson of the University of Maryland authored papers concerned with
gravitational radiation in the limit of high frequency (Isaacson, 1968). L.P. Grishchuk
and M.V. Sazhin (1973) published a paper on emission of gravitational waves by an
electromagnetic cavity, which also involved HFGWs, and V.B. Braginsky and Valentin
N. Rudenko (1978)wrote about gravitational waves and the detection of gravitational
radiation.
Literature
Also discussed in the literature are possible mechanisms for generating cosmological
HFGWs, including relativistic oscillations of cosmic strings (Vilenkin, 1981), standard
inflation (Linde, 1990), and relativistic collisions of newly expanding vacuum bubble
walls during phase transitions (Kosowsky and Turner, 1993). The theme of relic or
“big-bang”-generated HFGW and its relationship to “String Cosmology” (roughly
related to the well-known contemporary string theory) was suggested by G.
Veneziano (1990), and later discussed by M. Gasperini and M. Giovannini (1992).
High-frequency relic gravitational waves or HFRGWs were produced by the big bang
in a fashion somewhat similar to the cosmic microwave background. They were
discussed originally by Halpern and Jouvet (1968) and later by Grishchuk (1974,
2007), Beckwith (2008) and since then have emerged as having significant
astrophysical and cosmological importance.
This work continues today, especially the research of L.P. Grishchuk and Andrew
Beckwith, and is the motivation for HFGW detectors under development at
Birmingham University (England), INFN Genoa (Italy), the National Astronomical
Observatory of Japan (a 100MHz detector), and Chongqing University (China).
Sharp Peak at 10 GHz
The Synchro-Resonance Solution
•
•
The synchro-resonance solution of Einstein’s field equations, exploited in the present
proposal, is different from the Gertsenshtein (1962) effect. The more recent solution
identifies a coupling between EM and gravitational waves (Li, Tang and Zhao,
1992) that arises according to the theory of relativity. A static magnetic field, B, in
the y direction is superimposed upon a GW in the z direction propagating
perpendicular to the field direction as in the inverse Gertsenshtein effect, but that
there is an additional EM wave, in the same z direction as the GW In this case, a firstorder perturbative photon flux (PPF) will be generated in the x direction, and if this
PPF can be isolated and distinguished from effects of the superimposed EM wave,
then it enables detection of the GW.
This detection flux (PPF) is generated when the two waves (EM and GW) have the
same frequency and a uniform phase difference as the EM wave propagates along
the z-axis path of the GW (i.e., they are coherent in both space and time, the
synchro-resonance condition). The PPF, or detection photons, are produced at the
intersection of the static magnetic field, B, and the EM wave (origin of the y and z
axes), and travel perpendicularly (in both directions on the x axis) to the static
magnetic field (y direction) and to the EM wave (z direction). Therefore, the PPF can
be intercepted by receivers located in regions in the detector (on the x axis away from
the z axis)) that are relatively noise-free since the photons from the EM wave
(background photon flux, BPF, or noise) travel only in the z direction and, except for
scattering, will not reach the detectors located on the x axis.
General Concept of the HFGW Detection
Concept Tested in the Literature
• It should be noted that the identification of this coupling,
upon which the Li-Baker HFGW detector is based, is not
so new that it is untested in the literature. At least ten
peer-reviewed research publications concerning the
theory have appeared since Li’s first 1992 paper,
including those by Li and Tang (1997), Li et al. (2000), Li
and Yang (2004), Baker and Li (2005), Baker, Li and Li
(2006), Baker, Woods and Li (2006), Li and Baker
(2007), Li, Baker and Fang (2007), Baker, Stephenson
and Li (2008), and Li et al. (2008).
Schematic of Design
Li-Baker Detector:
Fractal Membrane
Gaussian beam
Signal PPF
Vacuum/Cryogenic
containment Vessel
Signal PPF
z
N magnetic pole
Microwave receiver
Detector #2
Microwave receiver
Detector #1
x
S magnetic pole
y
HFGW signal
Notional Drawing of Li-Baker Detector
Detection Limit
• For a stochastic GW it is:
• hdet = (1/Q)1/2(ћ/E)1/2, where hdet is the metric
(strain) detection limit in m/m,  is the frequency
of sensed gravitational waves (typically around
10GHz in the Li-Baker detector), E is the
effective energy contained within the detector
cavity summed over the detection averaging
time, and Q is the quality factor or selectivity of
the signal over noise.
Minimum Detectable HFGW
• The predicted maximum quality factor will
be Qtotal = 2.11039. This gives the
Standard Quantum Limit (SQL) for
stochastic GW detection at 10GHz
(essentially Heisenberg's uncertainty):
• hdet = (1/Q)1/2(ћ/E)1/2 = 1.810–37m/m.
This figure represents the lowest possible
GW amplitude detectable
Only Photon-Signal Limited
• Since the predicted best sensitivity of the
Li-Baker detector in its currently proposed
configuration is A = 10–32m/m, these
results confirm that the Li-Baker Detector
is photon-signal limited, not quantum
noise limited; that is, the Standard
Quantum Limit is so low that a correctlydesigned Li-Baker detector can have
sufficient sensitivity to observe HFRGWs
of amplitude A  10–32m/m
Low Development Risk Since Mainly Off-theShelf Components
• Use will primarily be made of “off-the-shelf”
components, and components described in the
open scientific literature and in the various
patents issued to Project Scientist Robert M L
Baker, Jr. (Baker, 1999, 2000, 2001, and
Patents Pending). Other components will be
designed by the project participants during the
Detector Design (DD) process. The project plan
and timing are described below
DD1.1 Containment Vessel
• DD1.1.1 Selection of material for the
containment vessel (e.g., Aluminum, stainless
steel, Titanium…)
• DD1.1.2 Detailed design of brackets and
fixtures for the internal equipment, wiring,
piping and through-wall connections
• DD1.1.3 Design of vacuum system
• DD1.1.4 Detailed design of size and shape of
containment vessel
DD1.2 Signal Processing
• This task will require the conceptual
design of digitizing hardware and software
to handle the data gathered, including the
combination of multiple detector signals,
the use of delay histograms, statistical
filtering techniques, and the study of false
alarm pitfalls in non-linear signal
processing.
DD1.3 Microwave Transmitter
(Gaussian beam)
• This Task is expected to study 10 W to possibly
10,000W (1,000W nominal) microwave
transmitters at around 10GHz, with an
associated power supply and appropriate safety
interlocks. Possible technologies include solidstate, magnetron, traveling-wave tube (TWT), or
high-power klystron, and specifications will be
developed under this component of the work.
• Microwave absorbing system (maybe exterior)
will be designed to protect refrigeration system.
DD1.4 Fractal Membranes and
Microwave Absorbers
• DD1.4.1 Design of the fractal membrane
(FM) reflectors
• DD1.4.2 Faraday Cage
• DD1.4.3 Selection of appropriate
microwave absorbing material
Fractal-Membrane-Reflector Component of Li-Baker High-Frequency
Gravitational Wave Detector. Fabricated in Hong Kong, displayed by
Bonnie Baker, May 2008 (Also constructed from solid copper, aluminum
and stainless steel)
Fractal Membrane Reflectivity
Detector Geometry & Fractal
Membranes
• GW/EM
Interaction
(along Z axis)
• Perturbative
Photon Flux
Release Direction
(along X axis)
Background is in Z; Signal is in X.
(Signal photon noise limited,
Not background noise limited.)
Baffle Configuration
X
axi
s
Z axis
Superconductor or microwave absorbing Baffles further
reduce background noise, and may be used on z and on x
axes,
and do not need to be cooled to same level as detectors
(500mK vs. 20mK).
DD1.5 Detection Receivers
• DD1.5.1 Off-the-shelf microwave horn
plus HEMT detector/receiver
• DD1.5.2 Rydberg-Cavity Detector
• DD1.5.3 Circuit QED microwave
detector
Detector First Option Consumer Off
the Shelf (COTS)– Available Now
(Figure: DMR Receiver
Components,
NASA, et al., 2007)
First Option: If plentiful signal strength is available (10’s to 100’s of photons
per sample) then standard microwave horns may be used, coupled to
High Electron Mobility Transistor (HEMT) amplifiers.
- The example pictured is a receiver assembly from the DMR Receiver that
flew on a space-borne COsmic Background Explorer (COBE) mission.
DD1.6 Cryogenic System
• DD1.6.1 Off-the-shelf cryogenic
systems
• DD1.6.2 Specifications for system best
suited to the detector
Cryogenic System
DD1.7 Electromagnet
• DD1.7.1 Off-the-shelf hardware
• DD1.7.2 Emerging technology
Schedule of Design Phase
• Gannt chart:
M2
M4
M6
M8
M10
M12
M14
M16
M18
M20
M22
M24
Systems Engineering Tasks
Requirements
Review
Detector Link Budget
SNR
Review
ICD
Review
Component Reqts Development
Interface Reqts Devl
Test
Plan
Review
Test Plan Development
Component Engineering Tasks
1.1.1, 1.1.2 Vessel Design
1.4.1 Fractal Membrane Signal Reflector Design
1.4.2,3 FM Int.
PDR
1.6.1 Cryogenic System Trade
PDR
1.2 Signal Processing Algorithms Trade
1.7 Magnetic Source Design Trade
1.3 Microwave Transmitter (GB)
CDR
PDR
1.4 Fractal Membrane Specs
PDR
CDR
PDR
1.6.2 Cryo System Spec
CDR
Sig Proc SW Design Spec
PDR
1.5 Microwave Receivers Trade
1.1.4 Vessel Spec
1.1.3 Vacuum Sys
PDR
Sig Proc HW Design Spec
CDR
CDR
Rcvr Design
1.5 Detection Receiver Specs
PDR
Decisio
CDR
n
Magnet Design
Magnet Spec
PDR
Decisio
CDR
n
GB Spec
CDR
Conclusions
• The outcome of the first-phase study will be an
engineering-ready design for a relic HFGW
detection system as described in the previous
slides. Following submission of a subsequent
proposal, this design will be implemented with
additional funding in the 2011 – 2012 timeframe. This experimental Li-Baker detector
facility will achieve ultra-high sensitivity detection
of gravitational waves, of 10 -32 amplitude, in a
completely new frequency band of cosmically
generated relic HFGWs in the 10GHz range.