1. 1 ACT  Atacama Cosmology Telescope  Funded by NSF  Will measure CMB fluctuations on small angular scales  Probe the primordial power spectrum and the growth of structure

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3. 3 The M illimeter B olometric A rray C amera: 3000 Detectors Tricolor : 145, 225, & 265 GHz 3 independent 32x32 arrays TES PUDs from GSFC PUDs = Pop-Up Devices TES = Transition Edge Sensor Each pixel: 1 mm x 1 mm TDM Multiplexing 2-stage 1x33 mux chips, followed by Series Array SQUID s: SAs -- from NIST Nyquist inductors -- from NIST Mux servo electronics & DAQ from UBC (who provided these for SCUBA)

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5. 5 ACT COLLABORATIONS Schools Government LabsMuseums …united through research, education and public outreach. PENN Haverford Princeton CUNY Toronto Cat Ó lica Kwa-Zulu Natal

6. 6 Simulations of mm-wave data. Survey area High quality area 150 GHz SZ SimulationMBAC on ACT 1.7’ beam 2X noise PLANCK MAP PLANCK

7. 7 Where will we be with CMB Bond et al. astro-ph/046195

8. 8 Cosmic Timeline for ACT Science z = 1000 t = 4 x 10 4 yrs z = 7 t = 3 x 10 6 yrs z = 1 t = 1 x 10 9 yrs z =.25 t = 12 x 10 9 yrs now First galaxies Universe is reionized Ostriker-Vishniac Surveys of Sunyaev-Zel’dovich (SZ) clusters Diffuse thermal SZ Kinetic SZ signal Initial conditions for structure formation N(mass,z) – Evolution of Cosmic Structure Lensing of the CMB The growth of structure is sensitive to w and m n Additional cross-checks from correlations among effects Extraction of cosmological parameters Primary CMB CMB Lensing OV/KSZDiffuse Thermal SZ Cluster Surveys

9. 9 SZ Signature Hot electron gas imposes a unique spectral signature NO SZ Contribution in Central Band 145 GHz decrement 220 GHz null 270 GHz increment 1.4 ° x 1.4 °

10. 10 Coordinated Cluster Measurements Identify and measure >500 clusters in an unbiased survey with multi-wavelength observations Galaxy Cluster HOT Electrons Mass limits of 3 x 10 14 estimated from simulations Science derived from N(mass,z)

11. 11 Southern Africa Large Telescope SALT has achieved 1” seeing World’s Largest Optical Telescope SALT will survey the ACT strip in 4 colors and will then measure spectra for tens of galaxies per cluster

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13. 13 CMB -1850 (  K) 0 1820 Lensing of the CMB 1.4 ° x 1.4 ° Lensing arises from integrated mass fluctuations along the line of sight. The CMB acts as a fixed distance source, removing the degeneracy inherent to other lensing measurements. Signal at l = 1000-3000 Image distortion – only a minor effect in the power spectrum. Must have a deep, high fidelity map to detect this effect.

14. 14 Lensing of the CMB -34 (  K) 0 34 1.4 ° x 1.4 ° Lensing Signal RMS signal well above noise floor. Isolate from SZ and point sources spectrally. Identify with distinctive 4-point function. 2% of CMB RMS

15. 15 Where are the baryons?  Cross-correlate galaxy counts and kinetic SZ signal KSZ signal proportional to  v KSZ signal proportional to  v Measure T KSZ ^2 as a function of galaxy positionMeasure T KSZ ^2 as a function of galaxy position Use redshift distribution to predict v, correlate density/velocity field and measure Use redshift distribution to predict v, correlate density/velocity field and measure  Estimates suggest high S/N detection for ACT and should be much better for 1 mm CCAT Estimates suggest high S/N detection for ACT and should be much better for 1 mm CCAT

16. 16 ACT \REGION: Target for future lensing surveys ACT will begin surveying in 2006 We already plan deep multi-band imaging with SALT of low extinction part of ACT strip (200 square degrees) Would be a very interesting target for a lensing survey

17. 17 ACT is but one of several next generation CMB experiments  APEX (Atacama Pathfinder Experiment) UCB/MPI UCB/MPI 1.4mm and 2 mm obs. 1.4mm and 2 mm obs. SZ science SZ science  SPT (South Pole Telescope) 8m at South Pole 8m at South Pole Chicago group (2008) Chicago group (2008) Large area Large area Optimized for SZ/clustersOptimized for SZ/clusters