Presentation on theme: "Li-Baker HFGW Detector Fabrication Plans and Specifications Development."— Presentation transcript:
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 first- order 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: x y z Vacuum/Cryogenic containment Vessel Microwave receiver Detector #2 Microwave receiver Detector #1 Gaussian beam Fractal Membrane Signal PPF N magnetic pole S magnetic pole HFGW signal Signal PPF
Notional Drawing of Li-Baker Detector
Detection Limit For a stochastic GW it is: h det = (1/Q) 1/2 (ћ /E) 1/2, where h det 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 Q total = 2.1 This gives the Standard Quantum Limit (SQL) for stochastic GW detection at 10GHz (essentially Heisenberg's uncertainty): h det = (1/Q) 1/2 (ћ /E) 1/2 = 1.8 10 –37 m/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 –32 m/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 correctly- designed Li-Baker detector can have sufficient sensitivity to observe HFRGWs of amplitude A 10 –32 m/m
Low Development Risk Since Mainly Off-the- Shelf 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 solid- state, 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 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). X axi s Z axis
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
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 time- frame. This experimental Li-Baker detector facility will achieve ultra-high sensitivity detection of gravitational waves, of amplitude, in a completely new frequency band of cosmically generated relic HFGWs in the 10GHz range.