Basic Concepts In CMB Detectors For Poets And Theorists .
Basic concepts in CMBdetectors for poets andtheorists – Part 2Lucio PiccirilloJodrell Bank Centre for Astrophysics - Manchester (UK)Advanced Technology Group
P0T T0 ΔTCGT01.2.3.4.Bolometer is a classical detectorProduces a Voltage prop. to the incident powerIs not sensitive to the phase of the incoming photonCan be very sensitive (limited by photon noise) but relatively slowresponse time5. Detects all kind of power: electrical, light, particles, etc.CMB and High Energy Physics16-24/07/2012
noise2. HEMT development and LNAsfor CMB researche ntrruCAsNLninoiseQL hv/(k ln2)frequencyCMB and High Energy Physics16-24/07/2012
How coherent radiometry worksphotonantennaamplifierAmplifier: from quantumto classical worldlightheatCMB and High Energy Physics16-24/07/2012Current/voltage
Quantum view of amplifier"Linear device that takes an input signal and produces an output signal byallowing the input signal to interact with the amplifier’s internal degrees offreedom"The input and output signals are carried by a set of “bosonic” modes [usuallymodes of the e.m. field]"Increases the size of the Signal without degrading (too much) the signal-tonoise ratio"Noise after amplification is much larger that the minimum allowed by QM"The signal can therefore be analyzed by our “dirty”, “grubby”, classical hands"Brings very delicate QM systems to our classical worldCMB and High Energy Physics16-24/07/2012
Quantum limit. ::::YS::CA". 4:V:: WPARTICLES AND FIELDSTHIRD SERIES, VOLUME 26, NUMBERQuantumTheoretical Astrophysics15 OCTOBER 19828limits on noise in linear amplifiersCarlton M. Caves130-33, California Institute of Technology, Pasadena, California 91125(Received 18 August 1981)How much noise does quantum mechanics require a linear amplifier to add to a signalit processes? An analysis of narrow-band amplifiers (single-mode input and output) yieldsa fundamental theorem for phase-insensitive linear amplifiers; it requires such an amplifier, in the limit of high gain, to add noise which, referred to the input, is at least as largeas the half-quantum of zero-point fluctuations. For phase-sensitive linear amplifiers,which can respond differently to the two quadrature phases ("cosset" and "sin&at"), thesingle-mode analysis yields an amplifier uncertainty principlea lower limit on the product of the noises added to the two phases. A multimode treatment of linear amplifiersgeneralizes the single-mode analysis to amplifiers with nonzero bandwidth.The resultsfor phase-insensitive amplifiers remain the same, but for phase-sensitive amplifiers therecorrections to the single-mode results. Specifically, there isemerge bandwidth-dependenta bandwidth-dependentlower limit on the noise carried by one quadrature phase of a signal and a corresponding lower limit on the noise a high-gain linear amplifier must add toone quadrature phase. Particular attention is focused on developing a multimode description of signals with unequal noise in the two quadrature phases.—I. INTRODUCTION AND SUMMARYThe developmentof masers in the 1950's madepossible amplifiers that were much quieter thanother contemporary amplifiers. In particular, thereemerged the possibility of constructing amplifierswith a signal-to-noise ratio of unity for a single incident photon. This possibility stirred a flurry ofperformance of "linear amplifiers" is now discussed in standard textbooks on noise" and quantum electronics. ' ) Contributing to a dwindling ofCMB and High Energy Physicsinterest were the difficulty of designing amplifiersperforthat even approached quantum-limitedmance and the dearth of applications that demanded such performance.Recently interest has re'vived'ofbecausea fortunate coincidence. The16-24/07/2012
PHYSI CAL REVIEWVOLUMEQuantum128, NUMBERDECEMBER 1, 19625Noise in Linear AmplifiersH. A. HAvsI'lectrica/ Engineering Department and Research Laboratory oj Electronzcs,Massachusetts Instztute of Technology, Cambridge, MassachusettsANDJ.A. MvLLENResearch Divisi on, Raytheon Company, Waltham, Massachusetts(Received May 10, 1962; revised manuscript received August 23, 1962)The classical definition of noise figure, based on signal-to-noise ratio, is adapted to the case when quantumnoise is predominant. The noise figure is normalized to "uncertainty noise. General quantum mechanicalequations for linear amplifiers are set up using the condition of linearity and the requirement that the commutator brackets of the pertinent operators are conserved in the amplification. These equations include asspecial cases the maser, the parametric amplifier, and the parametric up-converter. Using these equationsthe noise figure of a general amplifier is derived. The minimum value of this noise figure is equal to 2. Thesigni6cance of the result with regard to a simultaneous phase and amplitude measurement is explored."been presented in a paper by Louisell et al. ' We shall'HE availability of coherent signals at optical develop a unified set of equations for all "linear"amplifiers, special cases of which are the maser, thefrequencies has stimulated research in their useparametricamplifier, and the parametric up-converter.for communication purposes. Ways of processing opticalOnthebasisof these equations and the criteria of noisefrequencies are considered that are similar to those ofit will be possible to present a proof onperformance,AlfonsoMartinezthe low end of the coherent frequency spectrum. cheUniversiteitEindhovenachievable by any onethelimitingperformancethe use of classical communication techniques, classical5600 MB Eindhoven,The Netherlandsoftheseusedamplifierssingly or in combination withperformance criteria will be applied. One purpose ofEmail: alfonso.martinez@ieee.orgotherlinearTheconnection of the fundaamplifiers.this paper is to extend classical noise performancementalnoiseofthesewith the uncertaintyamplifierscriteria to linear quantum amplifiers in wbich the prewill be studied.principledomineer apoise is quotum mechanical in nature. TheseINTRODUCTIONQuantum Noise in Linear Amplifiers RevisitedAbstract—Thispaper presentsa modelas a photon gas. at optical frequencies, Var(wk ) %wk & ( %xk & ) Var(wk ). Wewill becriteriato a wideclassforofradiationlinear quantumappliedFor each frequency, the photon distribution is a mixture of Bose-Einstein reproduce the behaviourin Eq.(1) in both extremes. The differenceI. NOISEFIGUREmechanicaland Poisson amplifiers.distributions, respectively for thermal noise and the usefulbetweenthetworegimesisnowa function of not only ν and T , asinThe purposeof a noisesignal.Poisson (shot)contributesnoise at isall tofrequencies.sensitivelinearwithamplifierInin thethe usualnoiseclassicalof oftheory(i.e.As, noiseanalysis,but alsothe signalampliiiersenergy as dattenuators,thecrease the power, or photon Aux, of an incoming signalamplifierswitha veryit mayoperatinglargeis not additive,but signaldependent,well numberhappen thatofthe shotmodel gives a natural interpretation to the noise figure in terms of thewithas smallin thea noisecontaminationas possible so thatthe deteriorationof noise,the ess itself.noise prevailsover the thermaleven if hν ' kB Tratio.the signal may be conveniently detected at high poweras the signal passes the amplifier is used as a measureIII. M ODEL OF THE A MPLIFICATION P ROCESSI. I NTRODUCTIONlevels. The incoming signal,if used for communicationof amplifier noise performance. The signal-to-noiseAmplificationcorresponds to a change in the distribution of ζk . Wemodulacarriescoherentamplitudemodulation,Noise underdetectionis commonlyphasemodelledas [1] ratio (SNR) is definedpurposes,in the classical limit as themodelthischangefor each input photon, a (random)or somehνother type of ratio of signal powerstatistically:tion, frequency modulation, hνnoise power. . The probability that γ,(1)(ν) discuss problemsmodulation. Here weNshallhνnoisemainlyone photonsaCMBandHighamplitudemodulatedphase2may describek TandEnergyPhysicsare effectivelyoutputis Pr(γ). Linearityimplies that16-24/07/2012 1ampin the context of ampli6erse Bprocessingsinusoidal his, blackbodyradiationwith an additionalterm 2moduhν. At theriersnarrow bandamplitudeand/or phaseof the remaining photons in the mode. The mean of the amplifierreceptionadditional noiseA(ν)beis added;In process,lation.this connectionit mustthelowerA (t) do(t) cos/root go(t) R4y cosLcoot Qp(t) 1noted Cavesthat [2]output ζout is %ζout & %γ&%ζin &, and its variance,bounded ofA(ν)in terms of thephotons),presencea modulationof amplifierabandwidthgain8γ(ν)calls(infor 1 82, sinLcoot @p(t)11 . (1.1) (3),i.e.halfaA(ν) 1 γ(ν).Asγ(ν) ,A(ν) Var(ζout ) %γ&2 Var(ζin ) Var(γ)%ζin &.minimum 2rate of detection. The received signal2 must
s a model for radiation as a photon gas.distribution is a mixture of Bose-Einsteinctively for thermal noise and the usefulntributes with noise at all frequencies.of linear amplifiers and attenuators, theation to the noise figure in terms of theprocess itself.III. M ODEL OF THE A MPLIFICATION P ROCESSTRODUCTIONion is commonly modelled as [1]ehνhνkB T 1hν,2(1)with an additional term 12 hν. At thenoise A(ν) is added; Caves [2] lowerhe amplifier gain γ(ν) (in photons),γ(ν) , A(ν) 21 , i. e. half aNoise density can be well approximatedT hν.n the wave nature of light and makesstributions. In this paper we modelotons of various frequencies, a photondy which predictions of the Gaussianed within a photon gas model. Weoise, the existence of noise at opticalof linear amplification.GNAL ANDT HERMAL N OISE(t), transmitted over a channel withover a time interval of duration T , isers. A similar sampling theorem holdsa complex-valued wavefunction ψ. Thephoton energy via Einstein’s relationand frequency constraints, W T is thehich the photons can be placed.uch there may be an unlimited numbernote the number of photons in the k-thpresentation of the wavefunction ψk asthe number-states.of photons per mode is the sum of ahermal noise component xk , namelystatistics for wk and xk are Poissonrespectively. The Poisson distribution[3]. A Bose-Einstein distribution hased number of thermal photons per cellhνkkB T 1 1.iation, %xk & ee ratio at frequency νk , SNRk , as2k at optical frequencies, Var(wk ) %wk & ( %xk & ) Var(wk ). Wereproduce the behaviour in Eq. (1) in both extremes. The differencebetween the two regimes is now a function of not only ν and T , asin the usual analysis, but also of the signal energy as well. As noiseis not additive, but signal dependent, it may well happen that the shotnoise prevails over the thermal noise, even if hν ' kB T .%wk &2.Var wk Var xkAmplification corresponds to a change in the distribution of ζk . Wemodel this change statistically: for each input photon, a (random)number of output photons γ is generated. The probability that γphotons are effectively output is Pramp (γ). Linearity implies thatamplification takes place for every individual photon, independentlyof the remaining photons in the mode. The mean of the amplifieroutput ζout is %ζout & %γ&%ζin &, and its variance,Var(ζout ) %γ&2 Var(ζin ) Var(γ)%ζin &.(3)The change in signal-to-noise ratio between input and output isVar(γ) %ζin &SNRin 1 .SNRout%γ&2 Var(ζin )(4)This ratio depends on the signal statistics. For a coherent state, forwhich %ζin & Var(ζin ). We then define the noise figure F asF! 1 Var(γ)%γ 2 & .%γ&2%γ&2(5)As expected, F 1, an amplifier can only worsen the signal-tonoise ratio. Linear amplification admits a natural interpretation asthe change in the number of particles, and of their statistics. Addedamplification noise is related to the uncertainty in the amplificationprocess itself.With a thermal input, a noise temperature Teq can be definedTeq T (F 1) TVar(γ) hν1 e kB T2%γ&)Var(γ) hν,%γ&2 kB(6)' 1.where we assumed that khνBTWe recover the well-known formula F L for the noise figure ofan attenuator, a device which independently removes every photonwith probability π and lets it through with probability 1 π; its lossL is L (1 π) 1 1.This model can be easily used to derive Friis’s formula for a chainof n amplifiers, each with gain γν , it is easy to generalize Eq. (3) toobtain a formula for total change in SNR,SNRin 1 SNRoutnν 1Fν 1ν 1"ν ! 1 %γν &%ζin &.Var(ζin )Here it is!hνQL kB ln 2(7)R EFERENCES(2)ate regimes, classical and quantum. Atr(wk ) %wk & ' %xk &2 Var(xk );[1] B. M. Oliver, “Thermal and quantum noise,” Proc. IEEE, vol. 53, pp.436–454, May 1965.[2] C. M. Caves, “Quantum limits on noise in linear amplifiers,” Phys. Rev.D, vol. 26, no. 8, pp. 1817–1839, 15 October 1982.[3] L. Mandel and E. Wolf, Optical Coherence and Quantum Optics. Cambridge University Press, 1995.CMB and High Energy Physics16-24/07/2012
Amplifiers from the pastHigh frequency à Low noise à high carrier mobilityCMB and High Energy Physics16-24/07/2012
CMB and High Energy Physics16-24/07/2012
2. High Electron MobilityTransistors (HEMTs)"Mobility μ of electrons:v µE[ µ ] [cm 2 / (Vs)]MaterialElectron mobility(cm 2/Vs)Hole mobility(cm 900CMB and High Energy Physics16-24/07/2012
Mobility Modeling and CharacterizationElectrons and holes are accelerated by the electric fields, but lose momentum as a resultScattering mechanismsof various scattering processes. These scattering mechanisms include lattice vibrations (phonons),impurity ions, other carriers, surfaces, and other material imperfections. A detailed chart of mostof the imperfections that cause the carrier to scatter in a semiconductor is given in Figure 1.Scattering is important for noise"Scattering MechanismsDefect rier ScatteringAlloyIonizedLattice calPolarCMB and High Energy PhysicsFigure 1. Scattering mechanisms in a typical semiconductor.16-24/07/2012
Scattering vs temperature(noise better at low temperatures?)"Ionized impact scatteringµ II T"3/2Acoustic phonon scatteringσ 1 / µµ AC T 3/2CMB and High Energy Physics16-24/07/2012
Ionized Impact scatteringLow electron velocityHigh electron velocityHigher temperature lower scatteringCMB and High Energy Physics16-24/07/2012
Doping concentration and mobilityversus temperatureHigh purity Si1: N 1012 cm-32: N 1014 cm-33: N 2.3 1015 cm-34: N 4.9 1015 cm-3Penalty in mobility whendoping concentrationincreases!CMB and High Energy Physics16-24/07/2012
We need carriers! Is there a way to avoid themobility penalty as the doping concentrationincreases?"YES! Modulation doping: a mechanism thatproduces a 2D electron gas with high carriermobilityCharge transferΔEECCEgWGEgNGEVΔEVdopedundopedCMB and High Energy Physics16-24/07/2012
Electrons are spatially separated bydonors thus reducing the ionizedimpurity scatteringBand bending results as aconsequence of the charge transferand a 2D electron gas is generatedwith very high mobility. The spacerincreases the separation betweendonors and electrons.CMB and High Energy Physics16-24/07/2012
CMB and High Energy Physics16-24/07/2012
over as frome driveeouslyin thehavee anderminals nextirelessensingantage,e ultra-rocesss of itsHEMT0.1 µme 75%ntiationgThe key issues with the development of the InPHEMT process are in MBE growth of high qualityHEMT epitaxial material on 75 mm InP substrates,definition of 0.1 µm gates and repeatable gate recessetching and the development of a robust backsidedry via etch process. The InP HEMT epitaxialstructure shown in Figure 1 has been TRWísbaseline structure for low noise amplifiers for severalyears [1,2,6.7].Section of a HEMTsilicon nitridepassivationsource 0.10 µmT-gatedrain n InGaAsSi Planei InAlAsIn0.60 Ga0.40 Asi InAlAsInP SubstrateCMB and High Energy Physics16-24/07/2012
NOISE in FETs"For good low-noise devices:"""Good pinch-offLow parasitics Rg, RsHigh gmTmint(Rg Rs ) K r K ω C 2gmgmK, Kr : noise coefficientsRg : gate resistanceRs : series resistance including ohmic contacts and channel resistancet Ta/290gm : transconductanceCMB and High Energy Physics16-24/07/2012
Low Noise Amplifiers"Use HEMTs"We characterize them with the radiometer formula:ΔTrms ΔTrms TsysΔνTsys2 ΔνK/ HzK sec
Inside an LNA"Integrate a complete radiometer on a single module(MMIC)Figure 1: A 95-GHz module with the radiometric components integrated (left) and the 90-element 95-GHz arrayunder assembly (right).QUIET observes the four CMB patches listed in Table 1. Each scan is performed with a halfamplitude of 7.5 and repointed when the sky has drifted by 15 , making up deep coverages of
Let’s compare the noise1 x QLTable 2: Comparison of current, future and ultimate achievable sensitivity to CMB d)PLANCK HFINET/feed(a)[µKCMB sec1/2]120 (LFI)140 (LFI)180 (LFI)220 (LFI)60 (HFI)90 (HFI)275 (HFI)BolometerNET/feed (b)[µKCMB sec1/2]4538333133481603xQL HEMTCMB BLIP-1/2(c)2 NET/feedNET/feed(d)[µKCMB sec1/2][µKCMB 90Goal sensitivity of each feed to T ( Tx Ty)/2 and Stokes parameter Q or U, defined as ( Tx- Ty)/2.Sensitivity for 100 mK, Ge thermistor, Polarization-Sensitive Bolometer pair, assuming 1.0K RJ instrumentbackground, 50% optical efficiency and 30% bandwidth.Same for HEMT amplifier with noise 3x quantum limit over 30% bandwidth. The sensitivity quoted is 2 -1/2 x NET,to take into account the ability to measure Q and U simultaneously with appropriate post-amplification electronics.The ultimate limit to sensitivity to Q or U, for zero instrument background and a noiseless direct detector.A bolometric polarimeter requires a method of cleanly modulating the input polarization prior toLNAs above the blue line can be BLIP even with working at QLdetection. Cooled rotating waveplates would be extremely expensive and risky to implement. Analternative it so use Faraday rotation in cylindrical waveguide. A prototype 100 GHz polarizationmodulator based on this principle has been developed by our group, in collaboration with Todd Gaier andMike Seiffert at JPL, and appears quite promising. This “solid-state waveplate” allows the input
HEMT in space"A space mission for low frequencies ( 70 GHz) will becompetitive with bolometric missions."Example: a cluster of small, simple satellites forming aninterferometer for measuring the B-modes"Interferometer vs imaging à it is the subject foranother talk!"From the ground, having the atmosphere, if we reachthe QL, LNAs will be competitive with bolometersabove 70 GHz.
Comparing bolometers andHEMTs 1"Bolometers""""""""""Cryo LNAsDetect powerNo quantum limitBroadband thermalLarge formatNeed T0 300 mKLittle power dissipation"1/f dealt mechanicallyInterferometry possibleLittle digital""""""""Amplitude/phaseQuantum limitSensitive only RFMedium formatNeed T0 20KPower hungry1/f dealt electronicallyInterferometry standardTotally digitalCMB and High Energy Physics16-24/07/2012
Comparing bolometers andHEMTs 2"Bolometers"""""""Cryo LNAsNeed optics to formimagesPolarimeter complex(no simult. U&Q)"Need band-pass filtersMicrophonicsSensitive to TempfluctuationsComplex back-endelectronics"""""Interferometer with noopticsPolarimeter integrated(measure U&Q)Thermal filtersLittle microphonicsSensitive to RFIComplex back-endelectronics but digitalsampling possibleCMB and High Energy Physics16-24/07/2012
Bolometers are better (?)"No QL"Large format arrays"Limited by photon noise – in principle"Sensitive up to sub-mm/IR"Relatively simple fabrication techniques
HEMTs are better (?)"Dynamic range"Linearity"Dependence of responsivity on T0"Dependence of responsivity on IR power loading"Speed"Required operating temperature T0
bolometers together at the output of a single-mode feedhorn ensures well-matched beams on the sky. Dualanalyzers are thus relatively immune to common-mode noise sources, such as temperature drifts, gaindrifts, sky noise, and common-mode pickup from microphonics and electro-magnetic interference.From J. Bock, “Polarimetry in Astronomy”, 2003Figure 4: Sensitivity of bolometer- and HEMT-based receiver systems for CMB polarimetry. The goal sensitivities perfeed for Planck LFI (HEMT-based, solid circles) and Planck HFI (bolometer-based, solid squares) in polarizationsensitive channels. The sensitivity achievable with 100 mK bolometers, assuming 50 % optical efficiency, 30 %bandwidth, 5x dynamic range, and a 1 % emissive 60 K telescope (open squares) is about a factor of three better thanPlanck HFI, but does not allocate sensitivity to systems noise sources. Bolometer sensitivity compares favorably tothat of future HEMT amplifiers (open circles), calculated assuming 3x quantum-limited noise performance, 30 %bandwidth, and simultaneous detection of both Q and U. The ultimate background-limited sensitivity from the CMB,assuming 100 % efficiency and a noiseless detector, is shown by the solid curve.CMB and High Energy Physics16-24/07/2012Mechanisms such as rotating waveplates, wire grids, K-mirrors, and Fresnel rhombs12 are commonlyused to modulate polarization. Such mechanisms are challenging to implement at low temperature, and canintroduce pickup from microphonics or EMI into sensitive bolometers and low-noise readout electronics.Waveplates are difficult to operate over a wide spectral band, and must be stacked together to obtain wider
bolometers together at the output of a single-mode feedhorn ensures well-matched beams on the sky. Dualanalyzers are thus relatively immune to common-mode noise sources, such as temperature drifts, gaindrifts, sky noise, and common-mode pickup from microphonics and electro-magnetic interference.From J. Bock, “Polarimetry in Astronomy”, 2003Figure 4: Sensitivity of bolometer- and HEMT-based receiver systems for CMB polarimetry. The goal sensitivities perfeed for Planck LFI (HEMT-based, solid circles) and Planck HFI (bolometer-based, solid squares) in polarizationsensitive channels. The sensitivity achievable with 100 mK bolometers, assuming 50 % optical efficiency, 30 %bandwidth, 5x dynamic range, and a 1 % emissive 60 K telescope (open squares) is about a factor of three better thanPlanck HFI, but does not allocate sensitivity to systems noise sources. Bolometer sensitivity compares favorably tothat of future HEMT amplifiers (open circles), calculated assuming 3x quantum-limited noise performance, 30 %bandwidth, and simultaneous detection of both Q and U. The ultimate background-limited sensitivity from the CMB,assuming 100 % efficiency and a noiseless detector, is shown by the solid curve.CMB and High Energy Physics16-24/07/2012Mechanisms such as rotating waveplates, wire grids, K-mirrors, and Fresnel rhombs12 are commonlyused to modulate polarization. Such mechanisms are challenging to implement at low temperature, and canintroduce pickup from microphonics or EMI into sensitive bolometers and low-noise readout electronics.Waveplates are difficult to operate over a wide spectral band, and must be stacked together to obtain wider
ode signals by differencing both legs of the analyzer instantaneously. We have developed a compact dualalyzer (see Fig. 5) consisting of a pair of polarization-selective bolometers11 (PSBs). Placing thelometers together at the output of a single-mode feedhorn ensures well-matched beams on the sky.From J.DualBock, “Polarimetry in Astronomy”, 2003alyzers are thus relatively immune to common-mode noise sources, such as temperature drifts, gainfts, sky noise, and common-mode pickup from microphonics and electro-magnetic interference. quantum limit!gure 4: Sensitivity of bolometer- and HEMT-based receiver systems for CMB polarimetry. The goal sensitivities perd for Planck LFI (HEMT-based, solid circles) and Planck HFI (bolometer-based, solid squares) in polarizationnsitive channels. The sensitivity achievable with 100 mK bolometers, assuming 50 % optical efficiency, 30 %ndwidth, 5x dynamic range, and a 1 % emissive 60 K telescope (open squares) is about a factor ofthreebetterCMBandHighthanEnergy Physicsanck HFI, but does not allocate sensitivity to systems noise sources. Bolometer sensitivity compares favorably tot of future HEMT amplifiers (open circles), calculated assuming 3x quantum-limited noise performance, 30 %ndwidth, and simultaneous detection of both Q and U. The ultimate background-limited sensitivity from the CMB,16-24/07/2012
SKYOptics and then SKYHorn array and bolometer array: which one is cleaner electromagnetically?
And now A few interestinginstruments
3. HF Gravitational waves"Ground or space interferometers"Pulsars"CMB B-modes"What about different frequencies like very highfrequencies?CMB and High Energy Physics16-24/07/2012
Gravitational Wave Frequency Ranges"Strong science cases- well understood technology""""Pulsar timing 10-8 HzLISA/DECIGO 10-4 – 10-2 HzAdvanced LIGO 102 – 5 103 HzFirst Detections?Emerging science cases- new technology" Microwave Frequencies 108 – 1010 Hz" IR and Optical Frequencies 1012 – 1015 Hz or higherCMB and High Energy Physics16-24/07/2012
Possible Sources at Very High Frequencies ?"Early Universe""Kaluza-Klein modes from Black Holes in 5-Dgravity""Garcia-Bellido, Easther, Leblond, etcSeahra, Clarkson and Maartens, Clarkson andSeahraEM-GW mode conversion in magnetisedplasmas"Servin and BrodinCMB and High Energy Physics16-24/07/2012
Detector Possibilities"Laser interferometers losesensitivity as n increasesGraviton, gPhoton, ν"Use Graviton to Photonconversion in B Field"De Logi and Mickelson (1977)"Cross section for gνVirtual Photon( Static MagneticField , B)8πGB LSpin states of g, B and νΓ Σ3c2 2CMB and High Energy PhysicsB is magnetic field, L is path length16-24/07/2012
What are the fluxes ?"Cross Section G is small due to G/c3 factorbut this is per incoming graviton"Flux of gravitons is large due to c2/G factorc212 2Photon Flux Γω gwh16π G ω gw"Signal Power is PEMW 18µ0B 2 L2 K gw 2 h 2cSin 2 (α )CMB and High Energy Physics16-24/07/2012
Conversion GW à e.m wavesInverse-Gertsenshtein effectCMB and High Energy Physics16-24/07/2012
Conversion GW à e.m waves"Need smart transducerGW à EMW à waveguides à LNA à detection, orGW à EMW à lenses à CCD à detection"With EMW’s we can use standard techniques"Correlation receiver for a single baseline GWdetector or an imaging detector at opticalwavelengthsCMB and High Energy Physics16-24/07/2012
Instrument angular-acceptance/beam First tests at Birmingham create EMW’s completely insidesingle mode waveguide- simple geometry New detector requires GW-EMW conversion outsidemodified waveguide and at many anglesCMB and High Energy Physics16-24/07/2012
New instrument Correlatorg – waves à à e.m.- wavesMagnets & waveguideà single-mode RFWaveguidetaperCMB and High Energy PhysicsCryoLNA16-24/07/2012
Collection partConversionTallwaveguidevolumeCollection partMagnetsStandard singlemode waveguidePlane-waves / modesfrom differentdirections in inputFinite-element e.m. modelling (HFSS)Single-modeoutputCMB and High Energy Physics16-24/07/2012
New Detector- microwave"Partial list of problems:"""""""Conversion plane-wave à waveguide modesWaves from different directions à Mismatch withthe main waveguide modeGradient of e.m. intensity along conversionvolumeMagnetic field projection effectsDifference in waveguide phase-velocityMultiple reflections inside the waveguide structureEtc CMB and High Energy Physics16-24/07/2012
GW Correlation ReceiverCorrelator Sensitivity increase Narrower beam in the z direction CMB and High Energy Physics16-24/07/2012
Correlation receiver circuitryLPFBPFIF1900IN1IN2PS1Re20KCryoLNAC- LSB(LO- ‐Si)(2GHz)SignalSi(5GHz)USB(LO Si)(12GHz)CMB and High Energy Physics16-24/07/2012
Correlation receiverB’ham/M’cr GW prototype experimentssτ g b s / cV V1 cos[ω ( t τ g ) cVons.bantennaXV V2 cos(ωt )V1V2 [cos(ωτ g ) cos(2ω t ωτ g ) ] / 2averageCosineoutputRc [V1V2 cos(ωτ g ) ] / 2 [V1V2 cos( 2πυ b s / c)] / 2CMB and High Energy Physics16-24/07/2012
Synthesizing beams Effect of finite bandwidthSolution: addcompensate fo iSxyP(xy0( , s)g) Z0 B/2Transit of a point-likesourceA( , s)F exp( i2 g )dCMB and High Energy Physics0B/216-24/07/2012
Sensitivity ( Provisional )continuousCMB and High Energy Physics16-24/07/2012
Ideas for the (not so distant) futureWe are considering extending the Birmingham opticaldetector work using larger arrays feeding CCD detectorsCMB and High Energy Physics16-24/07/2012
Conclusion"In addition to the obvious sources at LIGO and LISA frequencies there may beGW radiation at microwave and optical although the sources are speculative"The prototype detectors using the graviton to photon conversion are relativelycheap to build"The Jodrell – Birmingham collaboration is studying the design of a singlebaseline interferometer operating at 5GHz and an optical detector (*)."The detector will locate sources in the sky(*) PMTs/CCDs coupled to superconductingMagnets inside a cryostat to give very high sensitivityCMB and High Energy Physics16-24/07/2012
ENDThank you
Quantum limit CMB and High Energy Physics 16-24/07/2012).::::YS::CA".4:V::W PARTICLES AND FIELDS THIRD SERIES, VOLUME 26, NUMBER 8 15 OCTOBER 1982 Quantum limits on noise in linear amplifiers Carlton M. Caves Theoretical Astrophysics 130-33, California Institute of Technology, Pasadena, California 91125 (Received 18 August 1981) How much noise does
Components of voice alarm systems - strong loudspeakers /strong Components using radio links Carbon monoxide detectors - point detectors Multi sensor fire detectors - point detectors using both smoke and heat detection Multi- sensor fire detectors point detectors using /p div class "b_factrow b_twofr" div class "b_vlist2col" ul li div strong File Size: /strong 2MB /div /li /ul ul li div strong Page Count: /strong 280 /div /li /ul /div /div /div
Intersubband n-type III-V material systems detector arrays 591 14.3. Normal incidence quantum well intersubband detectors 594 14.3.1. Si/Si, Ge intersubband normal incidence detectors 594 1-Х X 14.3.2. III-V system intersubband normal incidence detectors 597 14.4. Interband type II infrared superlattice detectors 600 14.4.1. rnSb/rnASj xSbx .
The power was located in green water. No buns puzzle some in the lead off the text. Random . model of printed word recognition, TRACE has three sets of interconnected detectors – Feature detectors – Phoneme detectors – Word detectors These detectors span different
Report on the Inaugural CMB Analysis Summer School . The future of CMB cosmology is one in which maps of the microwave sky can be cross-correlated with mea-surements at other wavelengths (including large-scale optical surveys) to constrain a host of cosmological and astrophysical . the participants were
bulk. Thus KA-B suggested measuring the dipole component of δ ν(y). Below we use the notation for C 1,kin normalized so that a coherent motion at velocity V bulk wouldleadto C 1,kin T 2 CMB τ 2V2 bulk /c 2,whereT CMB 2.725K is the present-day CMB temperature. For reference, C 1,kin 1(τ /10 3)(V bulk/100km/sec) µK. When computed from .
1) Smoke Detectors Most smoke detectors which operate alarms contain an artificially produced radioisotope: americium-241. Americium-241 is made in nuclear reactors, and is a decay product of plutonium-241. Smoke detectors/alarms are important safety devices, because of their obvious potential to save lives and property.
inhomogeneous and correlated noise), and a very promising application for the analysis of very large future CMB satellite mission products. 1. Introduction Duringthe pastdecadesincethe ground-breaking discovery of the cosmic microwave background ra-diation anisotropy by the COBE satellite
The book normally used for the class at UIUC is Bartle and Sherbert, Introduction to Real Analysis third edition [BS]. The structure of the beginning of the book somewhat follows the standard syllabus of UIUC Math 444 and therefore has some similarities with [BS]. A major difference is that we define the Riemann integral using Darboux sums and not tagged partitions. The Darboux approach is .
