1 / 17

Thoughts on Ground-based lensing measurements

Thoughts on Ground-based lensing measurements. Chao-Lin Kuo Stanford/SLAC KIPAC. The primordial, Gaussian E-polarization. Large Scale Structure. B-polarization. J Tolan. Lensing B -polarization is a LSS experiment. Hu , Huterer and Smith, 2006.

shandi
Download Presentation

Thoughts on Ground-based lensing measurements

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Thoughts on Ground-based lensing measurements Chao-Lin Kuo Stanford/SLAC KIPAC

  2. The primordial, Gaussian E-polarization

  3. Large Scale Structure

  4. B-polarization J Tolan

  5. LensingB-polarization is a LSS experiment Hu , Huterer and Smith, 2006 • Deep polarization measurements (4 mK rms) on 1.5% of the sky can significantly improve Planck+SNAP constraints on {w0, wa, Wk, ∑mn}, pL=wrL w=w0+wa(1-a) • There is a strong theoretical preference: w0= -1, wa=0, Wk <10-4 → lensing B provides a constraint on ∑mn

  6. The Status of B-Polarization Measurements (07/2009) Lensing B-mode Gravity wave r=0.1 Chiang et al. • QUaD/BICEP (50~100 detectors) still miss the (lensing) B-polarization by ~ 2 orders of magnitude. • The current round of experiments (~1000 detectors) can only hope for a statistical detection. • To perform high S/N imaging of lensing B-polarization, one must increase the survey speed by 102. • The ground based platforms (DASI “drum”, SPT) will be maxed out already in the current round of exp.

  7. The simple strategyto get ~10,000 detectors on the sky… • Use an optical design that has the largest possible focal plane area • Choose an aperture size that optimizes throughput/dollar

  8. Optics Comparison Gregorian Crossed Dragone • The advantage of a crossed-Dragone system • (1). > 4X more FOV area than a Gregorian • (2). Flat/telecentric focal plane, no re-imaging • Optics • Good polarization properties verified in numerous • studies • The required primary aperture for lensing • B-mode is ~2 meters – for 10m class telescopes • the measurements will be sensitivity (throughput) • limited, not resolution limited. Strehl Ratio H. Tran et al., CMBPOL Technology Workshop, 2008

  9. The simple strategyto get ~10,000 detectors on the sky… • Use an optical design that has the largest possible focal plane area • Choose an aperture size that optimizes throughput/dollar • The Proposed Experiment: An array of 5-10 crossed-Dragone multifrequency telescopes, each with ~2-meter primary aperture and ~2,000+ detectors

  10. A Pilot Project: one 1.5-2m telescope • Serving as the prototype for two experiments • Pol-Len: Polarimeter array for Lensing • EPIC-IM (in collaboration w/ JPL) • The telescope will be integrated with • Room temperature sources/detectors • A BICEP-2 style 512-detector bolometric receiver • A larger format camera – see the next page • Many issues can be characterized in full details with this pilot projet: • Near and far sidelobe responses, baffling • Infrared filtering • Magnetic field shielding • Detector loading • Mitigation of polarization systematics

  11. The expansion prospects (major technology dev. required) 1 Telescope + 8,000 bolometers 5-10 Telcps., each w/8,000 detectors (minor technology dev. required) LDRD funds 1 Telescope 1 Telescope + 512* bolometers 1 Telescope + 2,000 bolometers 5 Telescopes, each w/ 2,000 bolometers Deployment for field observations *# of detectors projected for 150 GHz EPIC-IM mission data/design feedback

  12. The “major” technology development • By reducing the size of the feeds • we can pack more detectors (~4x) onto the • focal plane (~1.5 fl) • The price to pay is increased spillover • – which must be intercepted at 4K • 8,000 detectors to read per dewar warm baffle cold stop Zotefoam Vacuum window IR filter Teflon (50 k) receiver cryostat HR-10 OFHC (4K) cold stop

  13. Also a great gravity wave B-mode experiment (for r<0.1) Compared to degree beam experiments (BICEP/Keck, ABS), a 2 m class telescope offers: • Smaller maps → lower noise • Smaller maps → potentially less foreground • Small beams → de-lensing possible • Small beams → less Beam systematics (Polarized Dust, 5%) 3.6 deg 7.2 deg 14.4 deg 28.8 deg

  14. The Trade-offs • No Half-Wave-Plate modulators. • No full - rotation. • Modulation relies on scanning – QUaD/BICEP style. • For the same , 2 possible angles can serve as a systematic check.

  15. Funding/fielding prospects • SLAC “LDRD” under review (1 telescope, warm tests) • An NSF proposal will go in this August (“Pol-Len1”, one telescope +mount+ receiver development) • BICEP/Keck collaboration supportive of the deployment of the telescope to the South Pole DSL site in 2011. Pending approval from NSF-OPP (office of polar programs). • We have not thought about how to fund the full array…Let me know if you have $ or are interested.

  16. The End.Question?

More Related