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Search for hidden sector photons in a microwave cavity experiment. John Hartnett, Mike Tobar , Rhys Povey, Joerg Jaeckel. DURHAM UNIVERSITY. The 5th Patras Workshop on Axions, WIMPs and WISPs. Frequency Standards and Metrology

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Search for hidden sector photons in a microwave cavity experiment

Search for hidden sector photons in a microwave cavity experiment

John Hartnett, Mike Tobar, Rhys Povey, Joerg Jaeckel


The 5th Patras Workshop on Axions, WIMPs and WISPs

Frequency Standards and Metrology experiment

Precision Microwave Oscillators and Interferometers: From Testing Fundamental Physics to Commercial and Space Applications


Michael E. Tobar

ARC Australian Laureate Fellow

School of Physics

University of Western Australia, Perth

Frequency Standards and Metrology Research Group

High-Precision Oscillators, experiment

Clocks and Interferometers

Generating and measuring frequency, time and phase at the highest precision


Research experiment

Testing fundamental physics

  • Lorentz Invariance

  • Rotating cryogenic oscillator experiment

  • Odd parity magnetic MZ Interferometer experiment

  • Generation and detection of the Paraphoton

    Commercial Applications

  • Microwave Interferometer as a noise detector

  • Sapphire Oscillators (room temperature and cryogenic)

    Atomic Clock Ensemble in Space (ACES) Mission

  • Australian User Group

  • Long term operation of high precision clocks


  • Cryogenic Sapphire Oscillators better than H-masers

  • With MIT, image black hole at the centre of the Galaxy

  • Within Australia -> SKA and VLBI timing

Microwave cavity modes
Microwave cavity modes experiment

  • Whispering Gallery modes WGE(H)mnp

    • Vertically stacked

  • TM0np (n = 0,1; p = 0,1,2,3)

    • Vertically stacked

  • TE0np (n = 0,1; p = 0,1,2,3)

    • Vertically stacked

Electric field strength
Electric field strength experiment


HEMEX Whispering Gallery Mode Sapphire resonator experiment

WGH16,0,0 at 11.200 GHz

Sapphire in cavity
Sapphire in Cavity experiment






secondary coupling probe




silver plated copper cavity

copper clamp



coupling probe

copper nut

Lower order modes
Lower order modes experiment

TE mode: Eθ field

Electric field strength1
Electric field strength experiment



Coupling to paraphoton
Coupling to experimentparaphoton

Form factor g
Form Factor |G| experiment

Paraphoton wavenumber

Cavity resonance frequency

Transistion probability
Transistion experiment Probability


|G|~ 1

Paraphoton mass

Resonance Q-factor

Probability of Detection experiment


Pem = 1 W, Pdet = 10-24 W, Q ~ 109,

χ ~ 3.2 × 10-11

Exclusion plot
Exclusion plot experiment

For 6 pairs of Niobium cylinders (stacked axially) with 2 GHz < ω0/2π< 20 GHz and ω0 k  0

Microwave cavities

Q~1011, ….6 orders of magnitude better than Coulomb experiment

Overlap integral g
Overlap integral |G| experiment

k0 =ω0/c (resonance)

kγ = paraphoton

kγ2 =ω2 – mγ2

Q factor te 0np
Q-factor TE experiment0np

  • Q =Rs/G

    G=Geometric factor & Rs = surface resistance

G [Ohms]

10 GHz mode

T ≤ 4 K Niobium Q~ 109

Freq [Hz]

Sumo cavity tm 010 mode
SUMO cavity: TM experiment010 mode

Wg modes
WG modes experiment

  • In sapphire very high Q ~ 109 without Niobium

  • ? G for high m seems small, need to confirm, as numeric integral needs to be checked

Detection? experiment

  • Assuming

    • detection bandwidth f = 1 Hz

    • receiver temperature T = 1 K (very good amp)

      thermal noise power kTf = -199 dBm

Challenges experiment

  • Isolation will be the biggest problem

  • Microwave leakage

  • Unity coupling probes to cavities

  • No reflected power

  • Tuning High Q resonances exactly to the same frequency