The direct search for solar axions + other exotica with CAST
K. Zioutas University of Patras, Greece
on behalf the CAST collaboration
Abstract: The working principle and the performance of the CERN Axion Solar Telescope (CAST) will be presented. CAST is sensitive also to other exotica like paraphotons [from the hidden sector] and to chameleons [candidates for the dark energy]. In addition, work is in progress for new windows-of-opportunity, e.g., as to whether CAST can become an antenna with built-in directionality for relic axions. To quantify such a performance for CAST, information about inner solar magnetic fields and the dynamic Sun can help.
13/5/2011 1 The cosmological inventory:
• But, what is dark energy or dark matter ?
M x (r) r
• A particle relic from GMthetotal Big(r) Bang is strongly implied for DM / DE Vr - WIMPs ? r - Axions ? ….??.. Beyond Standard Model physics!
2 Roberto Peccei Helen Quinn Physics motivation for axions: solve the strong CP problem: why nEDM → 0 spin-parity 0- ≈ πο, γ (M1) ~ stable!
Axions cosmology dark matter
solve solar problems?!
The new ~axion fingerprints from solar physics?
3 Sun: A perfectly shielded “radioactive” source of exotica Bsolar essential!
~106 years
~2 sec ν’s Axions E. Georgiopoulou / UoPatras Chameleons
1 km Paraphotons mfp γthermal ... 1cm WISPs -3000km 0km - 4mm + more?
Rsurface | 4 tachocline Solar Axions: SUN the convenient lab for new physics!?
Note:
Allowed emission of exotica < 10% Lsolar !!
+ gravitational self-trapping of massive ~axions/WISPs (yield ~10-7) accumulation over 4.5 Gyears …
… without visible ageing effects!
L.DiLella, K.Z., Astropart. Phys. (2003)
5 a-helioscope
6 H. Primakoff The Primakoff Effect 1951
axion
g
Behind all present axion work! ×B,Ε 7 CERN Axion Solar Telescope: QCD Axions or other exotica
Pierre Sikivie 1983
Signal: excess of X-rays during alignment over background Production: Primakoff effect Detection Inverse Primakoff: Thermal photons interacting axion interacting coherently with a strong with solar nuclei produce Axions. magnetic field (~B2) converts to a photon
Expected number of Photons: Differential axion flux on Earth da E 4.2keV Ng Pag S t dEa a dEa -17 Paγ 1.710 2 g aγ 10 1 10 GeV
CAST Status & Perspectives, Theopisti Dafni (UNIZAR), Moriond2010 9 The CAST experiment Location
CAST
10 Decommissioned prototype LHC dipole magnet. CAST B=9 T, L=9.26 m
α g
gvirtual X B
11 Tracking system precision
Several yearly checks cross-check that the magnet is Sun Filming following the Sun with the required precision • Twice a year (March – September) GRID Measurements Direct optical check. Corrected for optical refraction • Horizontal and Vertical encoders define the magnet orientation • Verify that the dynamic Magnet Pointing precision (~ 1 arcmin) is within • Correlation between H/V encoders has been our aceptance established for a number of points (GRID points)
• Periodically checked with geometer measurements
12 BarBE μM HECHEC XRT CCD
13 X-ray Telescope / CCD
Tracking Background Signal simulation
• Spot position well determined • Full sensitivity of telescope exploited
• Counts in the spot compatible with background level
• Background rate 1-7keV: ~ 8x10-5cts keV-1cm-2s-1
Solar axions! paraphotons, chameleons?
CAST Status & Perspectives, Theopisti Dafni (UNIZAR), Moriond2010 14 CAST phase II – principle of detection ma > 0.02 eV
X ray detector Transverse magnetic field (B) X ray axions A
L
• Extending the coherence to higher axion masses... • Coherence condition (qL << 1) is recovered
for a narrow mass range around mg
3 Ne: number of electrons/cm r: gas density (g/cm3)
15 CAST
CAST 0.01 0.1 m [eV] 1.
… sCAST: 1999 2020
17 How much beyond CAST? CAST (1999) NGAH (~2020)
ADMX
18 Towards a new relic axion antenna with CAST?
Dielectric waveguide inside the CAST magnet may perform as a new kind of “macroscopic fiber”, being a sensitive detector for relic axions:
~ 0.1 - 1 meV rest mass range (experimentally inaccessible)
19 • The fiber output is split in two ports by a, γ’, CH, ... means of an optical switch actuated by a TTL signal. Each port can be instrumented with a photon counter
• In the present configuration one port is coupled to a cooled Photo Multiplier Tube and the other is blocked, allowing on-line monitoring of the instantaneous background
• In future set-ups the second port will also be coupled to a detector, presumably a TES-based sensor, thus doubling the 20 “live” tracking time Solar paraphotons beyond SM physics
Hidden Sector particles Theoretically motivated
- kinetic mixing: γ ↔ γ’ oscillations
NO magnetic field! NO cold bores needed
Vacuum path length relevant for oscillations -> upstream in front of the detector
a good sensitivity requires: 3 ULB MMs & FS pnCCD
also for chameleons!
M. Davenport, S. Gninenko, S. Troitsky, C. Yeldiz, K. Z. (2011) 21 Paraphoton detection sensitivity Off-pointing Low energy threshold: MM + CCD!
Ideal XRT / CCD Solar paraphoton flux m=10eV. .
m=0.1eV > 1.0 keV . > 0.3 keV > 0.1 keV …………..
P r e l I m I n a r y ……………
10eV 100eV100eV 1keV 1keV 10keV 10keV
Lowering energy threshold – increases the sensitivity more flux
M. Davenport, S. Gninenko, S. Troitsky, C. Yeldiz, K. Z. (2011) 22 Solar Chameleons P. Brax, K. Z. PRD (2010)
• Chameleons are DE candidates to explain the acceleration of the Universe • Chameleon particles can be created by the Primakoff effect in a strong magnetic field. This can happen in the Sun. • The chameleons created inside the sun eventually reach earth where they are energetic enough to penetrate the CAST experiment. Like axions, they can then be back-converted to X-ray photons. • In vacuum, CAST observations lead to stronger constraints on the chameleon coupling to photons than previous exp’s. • When gas is present in the CAST pipe, the analogue spectrum of regenerated photons shows characteristic oscillations: ID
axion helioscope = chameleon helioscope, but @ LE!!
23 Solar Chameleons - CAST P. Brax, A. Lindner, K.Z. (2011)
vacuum 0.1 mbar
1 [keV] 1 [keV]
The analogue spectrum [/hour/keV] of regenerated photons as predicted to be seen by CAST: matter coupling = 106, B=30T in a shell of width 0.1R Regenerated chameleons. solar around the tachocline (~0.7R ). Core magnetic field = 100T solar
1 mbar
Low energy threshold + vacuum
[keV]
24 Corona … enigma…. 1939 2011 … ? the coronal heating mechanism remains unknown!
…. with ~axions, Chameleons, … WISPs?
B. De Pontieu, et al., Science 331 (2011) 55-58 http://www.sciencemag.org/content/331/6013/55.abstract See also http://www.sciencemag.org/content/suppl/2011/01/05/331.6013.55.DC1/De-Pontieu.SOM.pdf 26 ? CAST solar physics
axion signal 2 ( [Bʘ] + ρ ) (dis)appearance of photons
γ - deficit / excess
spatiotemporal dependence!! “unexpected” + Chameleons!
@ ARs
25 CAST @ the Sun? Note: Bʘ ignored sofar…
It is remarkable + fascinating that the Sun emits intense X-rays... mystery S. Tsuneta, AAPPS Bulletin, 19(#3) (2009) 11 http://www.cospa.ntu.edu.tw/aappsbulletin/data/19-3/11Hinode.pdf
Mystery or harbinger of exciting new physics CAST-like axion signature
27 Expected CAST-like signatures in space: 1996 -
Converted solar axion spectrum 2D simulation 16
8
0
5 10 RHESSI science nugget, Eaxion [keV] H. Hudson, 30.4.2007
Pseudoscalar conversion and X-rays from the sun -4 2 ED Carlson,L-S Tseng, PLB 365 (1996) 193 ma « 10 eV/c
28 2 ...observation IF max≈10-20[meV/c ] ...
… axion conversion @ photosphere absorption, …, down-comptonization, …
Questions!! Typical analog solar X-ray spectrum solar minimum solar maximum YOHKOH
Eγ ≈ 0.3 - 4 keV
K. Z., M Tsagri, Y Semertzidis, T. Papaevangelou, T. Dafni, V. Anastassopoulos, New J. Phys. 11 (2009) 105020 http://iopscience.iop.org/1367-2630/11/10/105020 29 Klaus Galsgaard Manolis Georgoulis Angelos Vourlidas
THANKS for discussions – teaching!!
Reproduced spectra from directly measured solar X-rays from: a) the main phase of a large flare with T∼20MK [7] (green dashed), b) a flare with RESIK and RHESSI (red dots), c) preflaring periods after having subtracted the main X-ray flare component from the original spectra [7] (purple histogram), d) non-flaring active regions with T≈6MK, i.e. sunspots (blue dots), e) non-flaring quiet Sun, with T≈ 2.7MK, at solar minimum with SPhinX (blue dashed line) [8]; this is also supported by the recent findings that in the Quiet Sun regions stronger magnetic fields occur in deeper layers than in the ARs [2], mplying more down-comptonization and giving rise to a larger slope. The initial broad solar axion spectrum is also shown shadowed (pink dashed line). Two GEANT4 simulated spectra following multiple Compton scattering from a depth of ∼350 km and ∼400 km are also shown for comparison (thin histograms), where the estimated plasma frequency, i.e., also the axion rest mass, is ∼17meV/c2. The uncertainty is a factor of ∼2, since the density changes by factor of ∼4 between the ∼300 km and ∼1000 km depth. Note the strong deviations of the indirectly derived spectra (grey lines) in the past [9] of the non-flaring quiet Sun at solar minimum and that of the active Sun at solar maximum below ∼ 1 keV (SPhinX measurements). The spectra are not to scale.
Z., Vafeiadis, Tsagri, Semertzidis, Papaevangelou, Dafni, Anastassopoulos, 6th Patras workshop, UoZurich, 2010 http://www-library.desy.de/preparch/desy/proc/proc10-03.pdf p. 89 30 E.g.: ?
• measured - bb ? Residual analog spectrum? • (measured)max – (measured)min
• (measured)quiet – (measured)active
Z., Vafeiadis, Tsagri, Semertzidis, Papaevangelou, Dafni, Anastassopoulos, 6th Patras workshop, UoZurich, 2010 http://www-library.desy.de/preparch/desy/proc/proc10-03.pdf p/89 31 CMB SUN
ΔΤ ≈ ± 200μK
ΔT/T ∼a few×10-5 ΔT/T ∼ 103
New physics! » new physics?! 32 Further reading:
• http://www.physik.hu-berlin.de/gk1504/events/springblockcourse2011/ 4 lectures to PhD candidates
• http://ctp.snu.ac.kr/axion/ ASK2011 / Seoul
• http://iopscience.iop.org/1367-2630/11/10/105020 review article http://www.annualreviews.org/doi/full/10.1146/annurev.nucl.56.080805.140513 review article
• http://axion-wimp.desy.de/ Proceedings PATRAS workshops
33 33 Thanks Sun!!
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