Photon Regeneration at Optical Frequencies

Transcription

1 Photon Regeneration at Optical Frequencies Andrei Afanasev Hampton University/Jefferson Lab 3 rd rd Joint ILIAS-CERN CERN-WIMPs Training workshop Patras,, Greece, June 22, 2007

2 Motivation for Axion Search Dark Matter problem Strong CP problem Axion hypothesis Low-energy physics Beyond Standard model PVLAS effect

3 Motivation for low energy studies Unsolved problem of mass hierarchy What is behind the mass values of leptons and quarks? Neutrino masses at sub-ev scale Strategy Increase energy (new accelerators) Explore low energies at sub-ev scales with high precision and sensitivity

4 matter/energy budget of universe Stars and galaxies are only ~0.5% Neutrinos are ~0.3 10% Rest of ordinary matter (electrons and protons) are ~5% Dark Matter ~30% Dark Energy ~65% Anti-Matter 0% axion a dark matter candidate

5

6 Original papers proposing a new pseudoscalar boson

7 PVLAS results Science, 17 March 2006 based upon experimental idea of L. Maiani,, R. Petronzio,, and E. Zavattini,, PLB 175, 359 (1986)

8 Dichroism rotation of polarization plane PVLAS Collab,, PRL 96, (2006) [hep-ex/ ]; ex/ ]; CAST Collab, Phys Rev D47, 3707 (1993)

9 Dichroism rotation of polarization plane Maiani et.al.,., Phy. Lett.. B175 (1986); M: inverse coupling K m :inverse compton wavelength k: light wavenumber ε = BextL 4M 2 sin kl k K m 2 2 N LK 4k 2 m 2 L: magnetic field region length N: number of traversals

10 Ellipticity dispersion: photon-axion mixing hep-ex/ ex/ (2005); Phys Rev D47, 3707 (1993)

11 ellipticity dispersion; photon-axion mixing M: inverse coupling K m :inverse compton wavelength k: light wavenumber ψ = B 4 M 2 ext 2 kl K 2 m 1 sin kl 1 1 LK 2k 2 m k K m 2 L: magnetic field region length N: number of traversals

12 Open mass range for axions the combination of accelerator searches, astrophysical, and cosmological arguments leaves open a search window 10-6 < m a < 10-3 ev

13 Volume 47, Number 2 (March 2007) A workshop at the Institute for Advanced Study paid much attention to a small-scale scale experiment that might have found the first direct indication of a new particle

14 Planned `Light-Shining Shining-Through-The-Wall Experiments to detect Axion-Like Particles

15 LIPSS collaboration A. Afanasev,, K. McFarlane, R.Ramdon, H.Brown,, C. Long Hampton University K. Beard, G. Biallas,, J. Boyce, M. Shinn Jefferson Lab O.K. Baker (*), M. Minarni Yale University (*) Spokesman

16 Photon Regeneration light shining through a wall couple polarized laser light with magnetic field Sikivie (1983); Ansel m (1985); Van Bibber et al (1987) P γ ϕ 1 4 ( gbl) 2 2 mϕ L sin 4ω 2 mϕ L 4ω 2 lnb photon (or photon-lnb) conversion probability photon-ps coherence; {} ~ 1 m φ2 < 4ω/L

17 boson coupling to photons pseudoscalar particle or Light, neutral boson coupling to photons pseudoscalar interaction L ϕγγ = 1 ) g v µν ϕ ϕfµν F = E 4M 4 v B in present case, use FEL laser light and magnetic field light polarization in direction of magnetic field we want to test PVLAS in a completely independent way

18 Rate estimates P = g 2 B 2 L 2 sin 2 (m 2 L/ω)/(4m 2 L/ω) 2 γ-a a prod prob g = coupling constant (1/M) B = magnetic field L = magnet length ω = light wavelength Y = n P 1 P 2 ε ( Ω/Ω)) (N r +2)/2 n = photon flux (#/s) P1 (P2) = production (regeneration) probability ε = detection efficiency Ω/Ω = solid angle N r = number of reflections +2)/2 yield (#/s)

19 parameters: initial run B-field: 1.7 T magnet length: 1.0 m IR FEL power 0.2 kw IR FEL wavelength 935 nm (1.3 ev) quantum efficiency 0.4 linear polarization 100% acceptance 90% expt l efficiency ~ 90% expected signal rate > 0.01 Hz at g aγγ = 1.7 x 10-6 GeV -1

20 rate estimate, as example... P = = g B L ; 12 ( B = 1.7 Tesla ; L = 1.0 meters) axion-photon conversion probability, P n r i s = = = = 200 watts (935 nm) γ ' s / s 2 Ω ni P ε q Ω Hz ( Ω Ω = 0.9 ; ε q = 0.4) photon rate, n (200 W) photon regeneration rate, r 1.7 T; 1 m magnet ε~ 0.4; Ω/Ω ~ 0.9

21 LIPSS sensitivity range JLAB in ~1 day with IR FEL

22 Jefferson Lab and the Free Electron Laser

23 JLAB facility spectroscopic range LIPSS IR run at 900 nm

24 JLAB FEL: regeneration experiment current planned

25 infrared FEL operational at 10 kw extracted power 800 nm; tuneable up to 75 MHz rep rate

26 The experiment is mounted in Laboratory 1 in the FEL Building. There are two GW magnets used for PS generation, and two for photon regeneration. (0.5 m long; 1.8 T each) Lab 1 in FEL Building 2 GW magnets (4 total) optical tables 32 ft 8 in LIPSS exp laser light 39 ft

27 LIPSS today

28 LIPSS detector

29 Princeton Instruments ACTON 10:400BR-LN q.e. high at 935 nm quantum efficiency (%) 50% wavelength (nm) LN2 cooled: 1.3 e/pix/hour dark noise!!! used 100 khz readout rate

30 Importance of vacuum Signal suppressed for air present in gen/regen magnets suppression factor mev mev pressure, Atm

31 Destructive interference in photon regeneration vs magnet length suppression L 2m suppression L 1.1m m, mev suppression L 3m m, mev LIPSS Present Configuration m, mev Longer magnets: less sensitivity in PVLAS region

32 not sensitive enough yet to cover full parameter space of PVLAS result, however did reach the sensitive region for scalar coupling LIPSS initial (IR) run light polarized perpendicular to B field preliminary preliminary

33 Periodic Magnetic Field: Opportunity at Optical Frequencies Removes q l<<1 constraint K. Van Bibber et al, PRL 59 (1987) 759 Can be used to measure mass m b AA, Baker, McFarlane et al, hep-ph/ ph/ Requires magnet length ~ m in IR; -Not practical for X-rays: X need ~ km-long magnets Similar effect from `phase shift plates Jaekel&Ringwald,, hep-ph/ ph/

34 Periodic magnetic field effect P γ φ P γ φ = g B L for m = g B tan ( 2 q 2 φ ql N = 0 )[1 ( 1) n cos( ql)]/ m, n 8 Suppression m, n Mass, ev

35 Periodic field for LIPSS in present configuration Each 1.1m magnet consists of 2 segments Polarity of the segments can be flipped 1 1 seg seg Mass, ev

36 Enhancement by Interference with reference beam (PSE) Van Bibber 87;AA, Baker, McFarlane et al. 06 S beam dump beam E1 magnet 1 E2 W magnet 2 B1 B2 B3 B4 D1 D2 D3 E3 detector

37 summary LIPSS has begun to test axion interpretation of PVLAS result data in scalar configuration uses JLAB FEL and its facilities use dipole magnets that are on-hand (~1.8 T) used ultra-low low noise CCD array 200 watts average power; light polarized perpendicular to B ran in Spring hours, 935 nm some reach into sensitive region of parameter space continue experiment in ~winter 2008 upgrade optics to get higher power additional diagnostic monitoring equipment get pseudoscalar data

38 Thank you!