1. Joseph Henry Laboratories of Physics, Jadwin Hall, Princeton University, Princeton, New Jersey 08544, USA
2. Department of Astronomy, University of Virginia, Charlottesville, Virginia 22904, USA
3. National Institute of Standards and Technology, Boulder, Colorado 80305, USA
4. Department of Physics, University of Colorado Boulder, Boulder, Colorado 80309, USA
5. Department of Physics, University of California, San Diego, San Diego, California 92093, USA
6. Department of Physics and Astronomy, University of Pennsylvania, 209 South 33rd St., Philadelphia, Pennsylvania 19104, USA
7. Kavli Institute for Cosmological Physics, University of Chicago, Chicago, Illinois 60637, USA
8. Department of Astronomy and Astrophysics, University of Chicago, Chicago, Illinois 60637, USA
9. Physics Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
10. Department of Physics, The University of Tokyo, Tokyo 113-0033, Japan
11. Kavli Institute for the Physics and Mathematics of the Universe (WPI), Berkeley Satellite, University of California, Berkeley, California 94720, USA
12. Research Center for the Early Universe, School of Science, The University of Tokyo, Tokyo 113-0033, Japan
13. Physics Department, University of California, Berkeley, California 94720, USA
14. Department of Physics, University of Milano-Bicocca, Piazza della Scienza 3, Milan (MI) 20126, Italy
15. NASA Goddard Space Flight Center, Greenbelt, Maryland 20771, USA
16. MIT Kavli Institute, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, USA