1. _______________________________ADMX The Axion Dark Matter Experiment Gianpaolo Carosi Lawrence Livermore National Laboratory USA ADMX Collaboration APS April Meeting 02/14/2010 This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

2. _______________________________ADMX Dark matter. We know neither what the “dark energy” or the “dark matter” is A particle relic from the Big Bang is strongly implied for DM —WIMPs ? —Axions ?

3. _______________________________ADMX The axion. The axion remains a very attractive dark-matter candidate (affirmed by HEPAP, DMSAG, etc.) The ADMX axion search is “definitive” and relatively inexpensive It comes from the “Pecci-Quinn solution” to enforce strong-CP It’s a pseudoscalar (  °-like), extremely light and weakly coupled 2  coupling (Primakoff effect) : Key to possible detection g agg KSVZ DFSZ

4. _______________________________ADMX Principle of the microwave cavity experiment [Pierre Sikivie, PRL 51, 1415 (1983)]  E/E ~ 10 –22 Resonance condition: h = m a c 2 [ 1 + O(  2 ~ 10 -6 ) ] Signal power: P  ( B 2 V Q cav )( g 2 m a  a ) ~ 10 –23 W Microwave Cavity Superconducting magnet Amp Medium Resolution Channel (Hotz talk) High Resolution Channel (Hoskin's Talk)

5. _______________________________ADMX ADMX collaboration University of Washington Leslie Rosenberg, Gray Rybka, Michael Hotz, Andrew Wagner, Doug Will, Jesse Heilman, Kyle Tracy, Miguel Morales University of Florida David Tanner, Pierre Sikivie, Neil Sullivan, Jeff Hoskins, Jungseek Hwang +, Catlin Martin Lawrence Livermore National Laboratory Steven Asztalos*, Gianpaolo Carosi, Darrell Carter, Chris Hagmann, Darin Kinion, Karl van Bibber # National Radio Astronomy Observatory Richard Bradley University of California, Berkeley John Clarke Sheffield University Edward Daw

6. _______________________________ADMX The Experiment Baffling Bucking Magnet SQUID “1K” Pot Microwave Cavity Main Magnet 13 Ton 8 Tesla in center bore 4m

7. _______________________________ADMX The Axion Dark Matter eXperiment Stage Phase 0Phase IPhase II Technology HEMT; Pumped LHe Replace w. SQUID Add Dilution Fridge T phys 2 K 100 mK T amp 2 K1 K100 mK T sys = T phys + T amp 4 K 3 K 200 mK Scan Rate  (T sys ) –2 1 @ KSVZ1.75 @ KSVZ5 @ DFSZ Sensitivity Reach g 2  T sys KSVZ0.75 x KSVZDFSZ OR AND !

8. _______________________________ADMX Conversion microwave photons are detected by one of the world’s quietest radio receiver Systematics-limited for signals of 10 -26 W ~10 -3 of DFSZ axion power (1/100 yoctoWatt).

9. _______________________________ADMX Prior ADMX results Three eras of (early) ADMX “Phase 0” (non-SQUID) operations Single cavity/medium-resolution channel 1995 to 1998, 2001 to 2003 –PRL 80 (1998) 2043 (PhD Thesis) –PRD 64 (2001) 092003 –PRD 69 (2004) 011101(R) (PhD Thesis) Four-cavity/medium-resolution channel 1999 to 2001 –PhD Thesis Single cavity/high-resolution channel 2003 to 2004 –PRL 95 (2005) 091304 (PhD Thesis)

10. _______________________________ADMX Phase I & II Upgrade path: Quantum-limited SQUID-based amplification SQUIDs have been measured with T N ~50 mK Near quantum– limited noise This provides an enormous increase in ADMX sensitivity

11. _______________________________ADMX Phase I upgrade (Started data taking in May 2008) Field compensation magnet for SQUIDs SQUID amplifier

12. _______________________________ADMX Now running in Phase I (SQUID amplifiers) Injected Power Noise floor

13. _______________________________ADMX Summary and Conclusions Successfully operated SQUID amplifier near 7 T B-field at pumped LHe temperatures (~ 2 k). Took Med. Resolution data at KSVZ sensitivity (812-860 MHz): Published results in PRL... see Michael Hotz talk (next)! Currently taking data to close out High Resolution channel. (will continue data-taking in both channels until May). See Jeff Hoskin's talk! Chameleon particle search: Proof of Principle (will be submitted for publication soon). See Gray Rybka's talk! Currently preparing for move magnet to UW in May/June timeframe. Phase II contruction (Dilution fridge + New Insert). DEFINITIVE SEARCH!

14. _______________________________ADMX

15. Overview Dark Matter and the Axion. The Axion Dark Matter Experiment. History and current status Summary and Future plans.

16. _______________________________ADMX The dark matter axion Pseudoscalar boson (μeV- meV) Velocity distribution: DM axions pick up kinetic energy from random gravitational kicks as they fall into the galactic gravitational well. Boltzmann-like distribution: mean velocity = virial velocity = 10 -3 c Non-Thermal distribution Coherent axion flows (see Jeff Hoskin's talk) Rest mass

17. _______________________________ADMX AMDX Phase 0 run summary Phase 0 scanned 461 < f 0 < 810 MHz in ~ 7 years –Net scan rate  0.5 MHz/day (at optimal f 0 ) But, lowest (most attractive) decade of axion mass spans 300 < f 0 < 3000 MHz Scanning the most attractive axion-mass decade requires a speed-up

18. _______________________________ADMX How to detect dark-matter axions (Sikivie, 1983) The SQUID amplifier and dilution refrigerator lower Ts

19. _______________________________ADMX Details of data acquisition & analysis

20. _______________________________ADMX Sample data and candidates

21. _______________________________ADMX Previous MedRes limits (Phase 0 - HFET amps) Particle Physics (limits in coupling assuming 450 MeV/cc density) Astrophysics (limits in density with set couplings) Definitive experiment requires achieving sensitivity to DFSZ model axions at fractional halo densities ( ρ < 450 Mev/cc). S.J. Asztalos et al., Astrophys. J. Lett. 571, L27 (2002)

22. _______________________________ADMX ADMX Phase I: Accomplishments to date. Successfully operated experiment with SQUID amp near 7 Tesla field Received: Oct 27 th, 2009 Accepted: Dec 22 nd, 2009 Published: Jan 29 th, 2009 DOI: 10.1103/PhysRevLett.104.041301 Covered 812 – 860 MHz = 48 MHz Total Run Time: 19 months Continuous Data Collecting: 8 months