John Hartnett, Mike Tobar, Rhys Povey, Joerg Jaeckel The 5th Patras Workshop on Axions, WIMPs and WISPs DURHAM UNIVERSITY.

SEARCH FOR HIDDEN SECTOR PHOTONS IN A MICROWAVE

CAVITY EXPERIMENTJohn Hartnett, Mike Tobar, Rhys

Povey, Joerg Jaeckel

The 5th Patras Workshop on Axions, WIMPs and WISPs

DURHAM UNIVERSITY

Michael E. Tobar ARC Australian Laureate Fellow

School of PhysicsUniversity of Western Australia, Perth

Frequency Standards and Metrology Research Group

Frequency Standards and MetrologyPrecision Microwave Oscillators and Interferometers: From Testing

Fundamental Physics to Commercial and Space Applications

High-Precision Oscillators, Clocks and Interferometers

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

Space

ResearchTesting fundamental physics

1. Lorentz Invariance2. Rotating cryogenic oscillator experiment3. Odd parity magnetic MZ Interferometer experiment4. Generation and detection of the Paraphoton

Commercial Applications5. Microwave Interferometer as a noise detector6. Sapphire Oscillators (room temperature and cryogenic)

Atomic Clock Ensemble in Space (ACES) Mission7. Australian User Group 8. Long term operation of high precision clocks

Astronomy9. Cryogenic Sapphire Oscillators better than H-masers10. With MIT, image black hole at the centre of the Galaxy11. Within Australia -> SKA and VLBI timing

Schematic of cavity experiment

Microwave cavity modes

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

Whispering Gallery modes

Electric field strength

WGE16,0,0

HEMEX Whispering Gallery Mode Sapphire resonator

WGH16,0,0 at 11.200 GHz

Cavity mounted inside inner can

Sapphire in Cavity

1911.83

copper nut

51.00

80

30 50sapphire

copper clamp

silver plated copper cavity

primarycoupling probe

secondary coupling probe

10

8

Lower order modes

TE mode: Eθ field

Electric field strength

TM010TE011

Coupling to paraphoton

Form Factor |G|

Paraphoton wavenumber

Cavity resonance frequency

Transistion Probability

Resonance Q-factor

couplingParaphoton mass

|G|~ 1

Assuming Pem = 1 W, Pdet = 10-24 W, Q ~ 109, χ ~ 3.2 × 10-11

Probability of Detection

Exclusion plotFor 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|

kγ = paraphotonk0 =ω0/c (resonance) kγ2 =ω2 – mγ

2

Overlap integral |G|

Overlap integral |G|

Overlap integral |G|

Q-factor TE0np

Q =Rs/G G=Geometric factor & Rs = surface resistance

G [

Ohm

s]

Freq [Hz]

10 GHz mode

T ≤ 4 K Niobium Q~ 109

SUMO cavity: TM010 mode

WG modes

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?

Assuming detection bandwidth f = 1 Hz receiver temperature T = 1 K (very good

amp)thermal noise power kTf = -199 dBm

Power@ 1paraphoton per second S/N = 1

freq hf/s dBm Seconds

10 GHz 6.63E-24 -202 2

1 GHz 6.63E-25 -212 21

Challenges

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