dark matter searches lecture 1. neutrinos and axions a ... · dark matter searches lecture 1....
TRANSCRIPT
Dark matter searches
Lecture 1. Neutrinos and axions
«ETTORE MAJORANA» FOUNDATION AND CENTRE FORSCIENTIFIC CULTURE
INTERNATIONAL SCHOOL OF SUBNUCLEAR PHYSICS
52nd Course: Status of theoretical understanding and ofexperimental power for LHC physics and beyond
28 June 2014 A. Bettini. Padova University and INFN; LSC 1
A. BettiniCanfranc Underground Laboratory. Spain
G. Galilei Physics Dept. Padua University. ItalyINFN
Dark matter searches
Lecture 1. Neutrinos and axions
A 80-year old unsolved problem
Fritz Zwicky, 1933: “If this [over-density] is confirmed we would arrive at theastonishing conclusion that dark matter {dunkle Materie} is present [in Coma] with amuch greater density than luminous matter.From these considerations it follows that the large velocity dispersion in Coma [andin other clusters of galaxies] represents an unsolved problem.” [S. van den Berghastro-ph/9904 251]
28 June 2014 A. Bettini. Padova University and INFN; LSC 2
F. Zwicky, Helv. Phys. Acta. 6, 110 (1933).
Dark Matter everywhereDark matter needed at all the scales and in all the epochs, in the same quantityEvidence coming only from gravitational interaction
Galaxy rotation curves
Bullet cluster merger 1E 0657-558Normal matter (X rays) pinkTotal matter (Grav. Lens.) blu
28 June 2014 A. Bettini. Padova University and INFN; LSC 3
Lars Bergström. Rep. Prog. Phys. 63(2000) 793 hep-ph/0002126
D. Clowe et al., Astr. Journ, 648:L109-L113,2006
CMB. Planck 2013H0=67.3±1.2 km s–1Mp–1≈≈1.5 x 10–42 GeV≈≈ 2.3 x 10–18 s–1
H0=67.3±1.2 km s–1Mp–1≈≈1.5 x 10–42 GeV≈≈ 2.3 x 10–18 s–1
28 June 2014 A. Bettini. Padova University and INFN; LSC 4
Planck 2013 results. XVI http://arxiv.org/pdf/1303.5076v3.pdf.
h2 H0 km s1Mp1 /100 2 0.45 1 Mpc = 3.1 1022 m
Gravitational LensingThe gravitational field of matter between us and the source deflects its lightAll matter distribution (luminous and dark) can be reconstructed
28 June 2014 A. Bettini. Padova University and INFN; LSC 5
BICEP 21 km from the South Pole
28 June 2014 A. Bettini. Padova University and INFN; LSC 6
BICEP2BICEP2 observes in a unique band at 150 GHz[but cross correlation checks with BICEP1maps @ 100 GHz]Telescope in a liquid He cryostat (@ 4 K).Aperture = 26 cmObserved 380 square degRefracting optical system equipped with afocal plane of 512 antenna coupled transitionedge sensor (TES) @ 270 mKOptics tube provides rigid structural supportfor the optical chain.The sub-kelvin focal plane assembly sitswithin a superconducting Nb magnetic shield.
28 June 2014 A. Bettini. Padova University and INFN; LSC 7
BICEP2 observes in a unique band at 150 GHz[but cross correlation checks with BICEP1maps @ 100 GHz]Telescope in a liquid He cryostat (@ 4 K).Aperture = 26 cmObserved 380 square degRefracting optical system equipped with afocal plane of 512 antenna coupled transitionedge sensor (TES) @ 270 mKOptics tube provides rigid structural supportfor the optical chain.The sub-kelvin focal plane assembly sitswithin a superconducting Nb magnetic shield.
http://bicepkeck.org/b2_respap_arxiv_v1.pdfhttp://www.cfa.harvard.edu/news/2014-05
http://www.cfa.harvard.edu/CMB/bicep2/
BICEP2•Inflation quantum effects @ energies near 1016 GeV, and timescales < 10–32 s.
•Quantization of the gravitational field + exponential expansion primordialbackground of stochastic gravitational waves with a characteristic spectral shape.
•These inflationary gravitational waves (IGW) local quadrupole anisotropies inCMB
•Polarization pattern will include a characteristic non-irrotational component (calledB-mode) at degree angular scales.
•Its amplitude depends upon the tensor-to-scalar ratio, r , which is a function of theenergy scale of inflation.
•However, gravitational lensing between CMB and us induces rot≠0 in the originallyirrotational field (E-mode)
•The IGW B -mode, however, is predicted to peak at multipole l=80 making itpossible to distinguish from lensing effects
PRL 112, 241101 (2014)arXiv:1403.3985v2
28 June 2014 A. Bettini. Padova University and INFN; LSC 8
•Inflation quantum effects @ energies near 1016 GeV, and timescales < 10–32 s.
•Quantization of the gravitational field + exponential expansion primordialbackground of stochastic gravitational waves with a characteristic spectral shape.
•These inflationary gravitational waves (IGW) local quadrupole anisotropies inCMB
•Polarization pattern will include a characteristic non-irrotational component (calledB-mode) at degree angular scales.
•Its amplitude depends upon the tensor-to-scalar ratio, r , which is a function of theenergy scale of inflation.
•However, gravitational lensing between CMB and us induces rot≠0 in the originallyirrotational field (E-mode)
•The IGW B -mode, however, is predicted to peak at multipole l=80 making itpossible to distinguish from lensing effects
BICEP2B-mode angular spectrumContinuous curve= lensing onlyDotted curve= with fitted B-mode added
PRL 112, 241101 (2014)arXiv:1403.3985v2
28 June 2014 A. Bettini. Padova University and INFN; LSC 9
H0=67.3±1.2 km s–1Mp–1≈ 1.5 x 10–42 GeVHI= 6.00±0.91 x 1014 GeVH0=67.3±1.2 km s–1Mp–1≈ 1.5 x 10–42 GeVHI= 6.00±0.91 x 1014 GeV
Energy density at inflation V 1/4 2.21016 r0.2 GeV
Caveat.Foreground due to powderspolarisation estimated, not measuredPLANCK 1 year r< 0.11Wait PLANCK delivery (soon?)
Caveat.Foreground due to powderspolarisation estimated, not measuredPLANCK 1 year r< 0.11Wait PLANCK delivery (soon?)
BICEP2. Foreground PRL 112, 241101 (2014)arXiv:1403.3985v2
•Galactic foreground (in the very clean angular range) r<0.01•Polarised powders foreground. No map available, cannot be measured from surface
•Consider different models
28 June 2014 A. Bettini. Padova University and INFN; LSC 10
Caveat.PLANCK 2013 r< 0.11Wait PLANCK delivery (soon?)
Caveat.PLANCK 2013 r< 0.11Wait PLANCK delivery (soon?)
Three candidates consideredDark matter is a big challenge for particle physics
A large number of candidates for dark matter have been imagined
We shall consider three of them, which require
less radical enlargement of the Standard Model
less arbitrary assumptions
•Right neutrinos (meaning negative chirality = γ5 eigenvalue)
•keV mass sterile neutrinos
•Axions (different fromAxion Like Particles, ALPs)
•Sub-meV mass pseudoscalar particle
•WIMPs
•SUSY neutralinos, assuming R parity conservation
28 June 2014 A. Bettini. Padova University and INFN; LSC 11
Dark matter is a big challenge for particle physics
A large number of candidates for dark matter have been imagined
We shall consider three of them, which require
less radical enlargement of the Standard Model
less arbitrary assumptions
•Right neutrinos (meaning negative chirality = γ5 eigenvalue)
•keV mass sterile neutrinos
•Axions (different fromAxion Like Particles, ALPs)
•Sub-meV mass pseudoscalar particle
•WIMPs
•SUSY neutralinos, assuming R parity conservation
Three neutrinos from LEP
LEPThe line shape of the Zwidth becomes largerpeak becomes lowerwith increasing neutrinos numbers
28 June 2014 A. Bettini. Padova University and INFN; LSC 12
N 2.984 0.008
Three neutrinos from cosmology
Neff 3.360.34
“effective” neutrino density=density of non interactingradiation (m < MeV) at decoupling.
Prediction of SM = N νeff=3.046 [Mangano et al. hep-ph 0506164]
Planck + CMB at High L + Polarisation (WP)
Cosmology gives two pieces of information on neutrinos
ν
28 June 2014 A. Bettini. Padova University and INFN; LSC 13
Neff 3.360.34
3 favoured, 4 not excluded
Upper limits on the sum of neutrino masses
m 0.66 eV (95%; Planck+WP+highL)
m 0.23 eV (95%; Planck+WP+highL+BAO)
During the large scale structureformation neutrinos velocities arelarger than the escape velocities fromthe smaller (galaxy clusters) structuresFreely streaming out, they slow downtheir growthEffect not seen limit on sumneutrino mass
Tighter constraint adding BAO
Neff 3.300.27ν
ν
ν
More than three?nmne appearanceContradictory “evidence” reported by LSND & MiniBoonE?Large systematic uncertaintiesLSND (1995) observed a 3.8 σ excess in anti νµanti νe. If oscillation ∆m2>0.2 eV2.KARMEN (2001) excluded almost all the LSND parameter spaceMiniBooNE (2007-9). νµνe. Higher E, same L/E. NO signal @ LSND claim. Excess at lowenergies, where background model is most uncertain, not compatible with oscillationsMiniBoone (2010) anti νµanti νe claims signal in oscillation region observing excess of20.9±14.0 events
28 June 2014 A. Bettini. Padova University and INFN; LSC 14
MiniBooNEarXiv:1207.4809v2
OPERA arXiv:1303.3953
ICARUS arXiv:1209.0122
Larger mixing regionexcluded by CNGS
ICARUSNeutrino 2014
More than three?nmne appearance
Larger mass region excludedby cosmology
15A. Bettini.
“neutrinos” are weakly interacting particles behaving as radiation @ decouplingLimits valid for masses <1 MeV“Neutrinos” saturate dark matter density for Σm≈10 eVHeavier “neutrinos” must be out of thermal equilibrium
S. Tremaine and J. E. Gunn, Phys. Rev. Lett. 42, 407 (1979)
More than three?ne disappearance
Gallium anomaly?Both GALLEX/GNO and SAGE performed two runs each with radioactive neutrino sourcesfor checking the overall extraction efficiencyAveraging (!?) the four ratios found/expected one finds R=0.86±0.05Neither experiment used R to calibrate due to due to the uncertainties in theνe+71Ga71Ge+e– (detector) and e– +51Cr51V+νe (source) cross sectionsTo be tested by Borexino + source
28 June 2014 A. Bettini. Padova University and INFN; LSC 16
Gallium anomaly?Both GALLEX/GNO and SAGE performed two runs each with radioactive neutrino sourcesfor checking the overall extraction efficiencyAveraging (!?) the four ratios found/expected one finds R=0.86±0.05Neither experiment used R to calibrate due to due to the uncertainties in theνe+71Ga71Ge+e– (detector) and e– +51Cr51V+νe (source) cross sectionsTo be tested by Borexino + source
More than three?ne disappearanceReactor antineutrino anomaly?2011. Th. A. Mueller et al. [Phys. Rev., C83:054615] re-evaluation of the reactor antineutrino flux.Up by 3%, with a systematic uncertainty of about 5%2011. G. Mention et al.[ Phys. Rev., D83:073006]: the average of the measured flux at distances <100 m accounts for only 0.943± 0.023 (2.5s). Claim evidence for sterile neutrino (!!)2013. C. Zhang et al. [Phys. Rev. D 87, 073018]. Nowq13 is known. Calculate flux at the distancesof the measurements. Extrapolate to 0 distance.0.959± 0.009 (exp)± 0.027(syst) of the Mueller re-evaluation; difference is 1.4sRecently (Neutriono 2014) confirmed by Daya Bay experiment
28 June 2014 A. Bettini. Padova University and INFN; LSC 17
Neutrino masses
Neutrino masses, which are not inthe Standard Model, looksubstantially different from theother partiles
28 June 2014 A. Bettini. Padova University and INFN; LSC 18
Neutrino masses, which are not inthe Standard Model, looksubstantially different from theother partiles
See-saw mechanism
MRTR
Assume neutrinos are Majorana particlesMajorana mass term allowed by SU2 x U1
L and L–B violation ate scale M, very large
Dirac mass term mDLR mD M
0 mDmd M
28 June 2014 A. Bettini. Padova University and INFN; LSC 19
0 mDmd M
Eigenvalues mlight mD
2
Mmheavy M
With mD≈VEV=υ ≈ 200 GeVmlight≈ 100 meVM ≈ 1014 - 1015 GeVClose to GUT and (BICEP2) inflation scales !!
νSMA. Boyarsky, O. Ruchayskiy, M. ShaposhnikovarXiv 0901:0011
•3 right neutrinos•A degenerate doublet 100 MeV scale•A singlet N1 at keV scale•Small neutrino masses “explained” bysmall Yukawa couplings (|y2|<10–13)
mlight ylight
2 2
M; mheavy M
28 June 2014 A. Bettini. Padova University and INFN; LSC 20
•N1 “explains” dark matter•Astrophysical and LEP limits areevaded assuming very smallmixing (q2<10–8)•N1 decouples from and is not inthermal equilibrium wit the rest•Decays N1 ν + γand otherchannels
νSMA. Boyarsky, O. Ruchayskiy, M.Shaposhnikov arXiv 0901:0011
28 June 2014 A. Bettini. Padova University and INFN; LSC 21
keV neutrino?arXiv:1402:2301
“Evidence” in a stacked XMMspectrum of 73 galaxy clusters withred-shifts 0.01 < z < 0.35Marginally statistically significant(about 3 σ)Corresponds to a minimum of theeffective detection areaDepends on the (concave) shape ofthe background modelDiscrepancies between line positionand intensity in different sub-samples
28 June 2014 A. Bettini. Padova University and INFN; LSC 22
“Evidence” in a stacked XMMspectrum of 73 galaxy clusters withred-shifts 0.01 < z < 0.35Marginally statistically significant(about 3 σ)Corresponds to a minimum of theeffective detection areaDepends on the (concave) shape ofthe background modelDiscrepancies between line positionand intensity in different sub-samples
mN= 7 keVq2 2 x 10–11
Next generation X-ray observatories(Astro-H) needed for a sensitive search
The strong CP problem
L
s8
12
G
G
s8
%GG
The QCD symmetry properties allow the presence in the Lagrangian of the term (G isthe gluon field strength)
that is pseudoscalar (violates P), changes sign under time reversal, hence violates CPNB. Corresponding term in electrodynamics can be eliminated, being AbelianThe phases in the mass term
Lm
s8
Arg DetM %GG
would violate CP too, but can be eliminated by a phase rotation. The physically meaningfulquantity is
28 June 2014 A. Bettini. Padova University and INFN; LSC 23
argdetM
It gives a time reversal violating neutron dipole momentdn / e : 1016 cm
The experimental limit |dn|/e <2.9 x 10–26 cm, corresponds to the extremely small upper limit
< 1010
Why isqso small?
would violate CP too, but can be eliminated by a phase rotation. The physically meaningfulquantity is
Peccei QuinnMake theqparameter dynamical introducing a new pseudoscalar fieldfa
Assume that the Lagrangian originally possesses a U(1) invariance involving the quarks Yukawacouplings.The U(1) symmetry spontaneously breaks down at the energy scale fa
L s8
%GG
afa
28 June 2014 A. Bettini. Padova University and INFN; LSC 24
R. D. Peccei and H. R. Quinn. Phys Rev Lett 38 (1977) 1440
The valley is extremely narrow, with a huge curvature. Very high frequency field oscillationsperpendicular to the valley correspond to very large masses and decay immediatelyOscillations along the canyon have zero frequency, corresponding to massless Goldston boson,the axion
a x,t fa x,t
Peccei QuinnQCD axial (ABJ) anomaly ('t Hooft) in non Abelian theories one vacuum state is chosenamong an infinity of possible vacua.The potential corresponds to a particular choice of the phase of the scalar vacuum expectationvalue.This phase appears in the fermion mass termsPQ showed that when all fermion masses are made real by rotations of the fermion fields, theresulting θ is zero.
The θ-term in the QCD Lagrangian can then be eliminated by absorbing it into the axion field,
28 June 2014 A. Bettini. Padova University and INFN; LSC 25
R. D. Peccei and H. R. Quinn. Phys Rev Lett 38 (1977) 1440
The θ-term in the QCD Lagrangian can then be eliminated by absorbing it into the axion field,
a a faThe topological charge densityinduced by topological fluctuationsof the gluon fields such as QCDinstantons, provides a potential forthe axion field which is minimized atzero expectation value
a 0
This second phase transition happens when the temperature is about ΛQCD
Invisible axions modelsIn the original PQ paper fa was tied to the EW breaking scaleThis was subsequently ruled out by the experiments
Models were later developed in which fa >> VEVma and the axion coupling to other particles very small: “Invisible axions”Extend SM with additional Higgs bosons, and/or fermions with PQ charge
In particular
KSVZ: J. E. Kim [Phys Rev Lett. 43 (1979) 103], M. Shifman, A. Vainstein, V. Zacharov[Nucl Phys B 166 (1980) 493]Additional heavy quarks with PQ-charges
DSZ: M. Dine, W. Fischler, M. Srednicki [Phys Lett B 104 (1981) 199, A. R. Zhitniski[Sov. J. Nucll. Phys. 31 (1980) 260]Two Higgs doublets, normal quarks and leptons have PQ charges
28 June 2014 A. Bettini. Padova University and INFN; LSC 26
Models were later developed in which fa >> VEVma and the axion coupling to other particles very small: “Invisible axions”Extend SM with additional Higgs bosons, and/or fermions with PQ charge
In particular
KSVZ: J. E. Kim [Phys Rev Lett. 43 (1979) 103], M. Shifman, A. Vainstein, V. Zacharov[Nucl Phys B 166 (1980) 493]Additional heavy quarks with PQ-charges
DSZ: M. Dine, W. Fischler, M. Srednicki [Phys Lett B 104 (1981) 199, A. R. Zhitniski[Sov. J. Nucll. Phys. 31 (1980) 260]Two Higgs doublets, normal quarks and leptons have PQ charges
Axion properties
ma
mu /md1mu /md
fm
fa; 6 meV 109 GeV
fa
If fa is very large, the axion is a veryweakly interacting sub-eV mass particle.It can contribute to dark matter
Axion is coupled to the photon
Ga4F%Fa GaE Ba
Axion is the Goldston boson of the broken PQ U(1) symmetryAxions have predictable properties, which depend mainly on faAxion mass is inversely proportional to fa
28 June 2014 A. Bettini. Padova University and INFN; LSC 27
Ga ; n
2 fa
mam
: 1Ga
2 ma3
1ma
5Axion decay in two photons = age of the universe for ma=20 eVOnly very small mass axions canbe dark matter
Coupling to fermionsC f2 fa
f5 fa Cf model dependent coefficient
n: number, order of 1
Axions couple to baryons and mesons too
Axion detection
Axions may be produced in the stars by Primakoff effectIn the Sun energy spectrum has a maximum at 3 keVFlux on earth
a Ga 1010 GeV 2 3.751015 m2s1
28 June 2014 A. Bettini. Padova University and INFN; LSC 28
Can be detected converting back to photons, X rays,in a strong magnetic filed
Neither axions or photons are propagation eigenstatesAxion-photon conversion should be viewed as an oscillationIt is at the basis of their detection
Bounds from astrophysics
28 June 2014 A. Bettini. Padova University and INFN; LSC 29
Axion photon coupling axion radiation by astrophysical bodiesToo large energy loss contradicts observed stellar evolution limits on the coupling
Where are the axions?
Scenario A.PQ symmetry breaks before inflation
fa >1038 GeV10–12 < ma < 10–2 eV
EXCLUDED
Scenario A.PQ symmetry breaks before inflation
fa >1038 GeV10–12 < ma < 10–2 eV
EXCLUDED
ma: axion massfa: energy scale of the breakdownma: axion massfa: energy scale of the breakdown
Scenario B.PQ symmetry breaks after inflationCosmic defects may decay to axions witha relative weightadec=0.2-200
fa=(8.7±0.2) x 1010 GeV (1+adec)–6/7
ma = (71±0.2) (1+adec)6/7 µeV
Axion mass is now predicted in anarrow range70 µeV < ma < 1.2 meV
Scenario B.PQ symmetry breaks after inflationCosmic defects may decay to axions witha relative weightadec=0.2-200
fa=(8.7±0.2) x 1010 GeV (1+adec)–6/7
ma = (71±0.2) (1+adec)6/7 µeV
Axion mass is now predicted in anarrow range70 µeV < ma < 1.2 meV
r 0.20.050.07
The BICEP2 measurement of the tensor to scalar ratiosharpens to a narrow mass range the predictions of the PQtheory
gives Hubble parameter at the inflation H I 61014 GeV and fa = 1015 GeV
28 June 2014 A. Bettini. Padova University and INFN; LSC 30
L. Visinelli and P. Gondolo arXiv: 1403.4594
Scenario A.PQ symmetry breaks before inflation
fa >1038 GeV10–12 < ma < 10–2 eV
EXCLUDED
Scenario A.PQ symmetry breaks before inflation
fa >1038 GeV10–12 < ma < 10–2 eV
EXCLUDED
Scenario B.PQ symmetry breaks after inflationCosmic defects may decay to axions witha relative weightadec=0.2-200
fa=(8.7±0.2) x 1010 GeV (1+adec)–6/7
ma = (71±0.2) (1+adec)6/7 µeV
Axion mass is now predicted in anarrow range70 µeV < ma < 1.2 meV
Scenario B.PQ symmetry breaks after inflationCosmic defects may decay to axions witha relative weightadec=0.2-200
fa=(8.7±0.2) x 1010 GeV (1+adec)–6/7
ma = (71±0.2) (1+adec)6/7 µeV
Axion mass is now predicted in anarrow range70 µeV < ma < 1.2 meV
CAVEAT: wait for confirmation or rebuttal by PlanckCAVEAT: wait for confirmation or rebuttal by Planck
Narrow window for axions
28 June 2014 A. Bettini. Padova University and INFN; LSC 31
Helioscopes and DM detectros look at too large masses and too large couplingsIf BICEP2 is right ADMX looks at too small masses
20 GHz ma / 2
Axion parameter spaceYellow excluded before BICEP2BICEP2: fa = 1015 GeVexcludes region on the leftColoured lines in the region on theright correspond to different modelsof axion production throughtopological defects decays
fa≈ 1012-1014 MeVma≈ 10–8-10–10 MeV
28 June 2014 A. Bettini. Padova University and INFN; LSC 32
CAST ma 0.1-1 eVIAXO ma 0.01-1 eV
fa≈ 1012-1014 MeVma≈ 10–8-10–10 MeV
fama 104 MeV2 mQCD QCD2
Large scales – small scales
28 June 2014 A. Bettini. Padova University and INFN; LSC 33
m VEV 2
M N
ma QCD
2
fa
HelioscopesAxion energy few (keV) photon frequency O(1018 Hz: X-rays)
a Ga 1010 GeV 2 3.751015 m2s1
28 June 2014 A. Bettini. Padova University and INFN; LSC 34
CAST
28 June 2014 A. Bettini. Padova University and INFN; LSC 35
Fanourakis CTEQ 2006
CAST p
2 Neqe
2
0me
k2 2 – p2
In its 1st phase CAST did not reach the axion regionIn its 2nd phase, the magnet was filled of 4He and subsequently 3He gasNe = number of electrons (free and bound) per cubic metreDispersion relation of the light above the plasma frequency (X-rays)
Photons behave a “free particles” on masswpCan be changed (scanned) by changing the gas pressureAt level crossing a togconversion probablity resonates
KSVZ axion reached, but atlarge mass (1 eV scale)
28 June 2014 A. Bettini. Padova University and INFN; LSC 36
M. Arik et al. Phys. Rev. Lett. 112, 091302, arXiv: 1307.1985
IAXO. International Axion ObservatoryLetter of Intent to CERN SPSC-I-242Same principles as for CAST, with several improvementsProjected sensitivity still around 0.1 eV masses
28 June 2014 A. Bettini. Padova University and INFN; LSC 37
Existing boundsAstrophysical bounds come primarily from not having observed effect on star evolution ofaxion radiation
28 June 2014 A. Bettini. Padova University and INFN; LSC 38
Axion Haloscope
28 June 2014 A. Bettini. Padova University and INFN; LSC 39
How ADMX works
28 June 2014 A. Bettini. Padova University and INFN; LSC 40
Gray Rybka - TAUP 2013 - Asilomar, CA - Sept. 10, 2013
ADMX Tuning rods
28 June 2014 A. Bettini. Padova University and INFN; LSC 41
ADMX. Results
28 June 2014 A. Bettini. Padova University and INFN; LSC 42
Gray Rybka - TAUP 2013 - Asilomar, CA - Sept. 10, 2013
ADMX. Next stepsScan speed to be increased by factor 100Scan speed ≈ 1/TnoiseReduce both physical and amplifier noise
28 June 2014 A. Bettini. Padova University and INFN; LSC 43
ADMX. Next steps
Higher frequency (10-100 GHz) resonators neededR&D programme ongoing by ADMXIncluding open resonators
28 June 2014 A. Bettini. Padova University and INFN; LSC 44
Gray Rybka TAUP 2013
Axions & photonsPropagation eigenstates are superpositions of the axion and electromagnetic fieldsIn an external magnetic field
2 k2 1 00 1
0 gaB
gaB ma2
A||
a
L ga4F%F gaB E
axion mixes with the A component parallel to the magnetic field
28 June 2014 A. Bettini. Padova University and INFN; LSC 45
Jaeckel and Redondo, arXiv:1308.1103
;gaBma
Dish experimentFocus light-axion wave with a spherical mirror in a strong magnetic fieldSensitivity dominated by S/N
DetectorCryogenic toreduce noise
Horns et al , JCAP04(2013)016
Assumequantum limit of the squid temperatureis reachedMirror area A=10 m2
Magnetic field B = 4 TBandwidth ∆w/w=106
Exposure life = 1 yrAxion mass ma=10 µeVSignal/Noise ≈ 14
28 June 2014 A. Bettini. Padova University and INFN; LSC 46
Jaeckel and Redondo, arXiv:1308.1103
DetectorCryogenic toreduce noise
Assumequantum limit of the squid temperatureis reachedMirror area A=10 m2
Magnetic field B = 4 TBandwidth ∆w/w=106
Exposure life = 1 yrAxion mass ma=10 µeVSignal/Noise ≈ 14
Signal proportional to ma–3/2
Axions in dwarf galaxiesMany dwarf galaxies exist in the local groupSome of them do not emit much light but appear reach of dark matterSignature for two-photon decay of axions is a very narrow and very weak line at ma /2Expect very narrow line ∆ν/ν 6
28 June 2014 A. Bettini. Padova University and INFN; LSC 47
Axions in dwarf galaxiesSearch with the Haystack radio observatory (on three dwarf galaxies)B.D. Blout et al., Astrophys. J. 546, 825 (2001)
28 June 2014 A. Bettini. Padova University and INFN; LSC 48
In the interesting axion mass rangeNeed improving sensitivity in ga by 5-6 orders of magnitudesUse larger telescopes.Progress in cryogenic detectors technique
THANK YOU
28 June 2014 A. Bettini. Padova University and INFN; LSC 49