bolometric adding interferometry mbi qubic l.
Download
Skip this Video
Download Presentation
Bolometric Adding Interferometry: MBI & QUBIC

Loading in 2 Seconds...

play fullscreen
1 / 21

Bolometric Adding Interferometry: MBI & QUBIC - PowerPoint PPT Presentation


  • 170 Views
  • Uploaded on

Bolometric Adding Interferometry: MBI & QUBIC. Peter Timbie University of Wisconsin - Madison. CMB Interferometers. Why CMB Interferometry? Systematics!. simple optics - beams can be formed with corrugated horn arrays

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about 'Bolometric Adding Interferometry: MBI & QUBIC' - abner


Download Now 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.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
bolometric adding interferometry mbi qubic
Bolometric Adding Interferometry:MBI & QUBIC

Peter Timbie University of Wisconsin - Madison

The Path to CMBPol

why cmb interferometry systematics
Why CMB Interferometry? Systematics!
  • simple optics
  • - beams can be formed with corrugated horn arrays
      • symmetric beam patterns, low sidelobes, no mirrors
  • - no off-axis aberrations
  • correlates Ex and Ey on a single detector to measure Stokes U (no differencing of detectors)
  • differences sky signals (measures visibilities) without scanning
  • simple observing strategy - measure U and Q on each field by rotating about optical axis
  • measures Temp and Polarization power spectra directly
  • angular resolution ~ 2X better than imager of equivalent diameter
  • coherent (HEMTs) or incoherent (bolometers) systems possible
interferometer beam systematics
Interferometer Beam Systematics

Interferometers measure visibilities:

n1

n2

y

i

uij

j

x

X

Beam mismatch, distortion, etc. do not couple T into

Stokes U visibility. [E.F. Bunn PRD 75, 083517 (2007)]

slide5

Beam Combination for Large N

  • Pairwise (Michelson): signals are split and combined pairwise
    • N(N-1)/2 pairs (78 for N = 13, 4950 for N =100)
    • multiplying correlator (coherent receivers only) a. analog (DASI/CBI) b. digital (most radio interferometers) - power? - bandwidth?
  • Fizeau (Butler): signals from all antennas appear at all detectors
    • Guided-wave adding interferometer (Butler combiner, Rotman lens)
    • Quasioptical adding interferometer using a telescope (MBI, EPIC-I, QUBIC)
adding interferometer for many horns

//

//

//

….

….

Adding Interferometerfor Many Horns

N horns

OMTs

2Nphase modulators

beam combiner

detectors

single-horn

auto-correlation

Stokes U visibilities

Stokes I visibilities

total power

slide8

Quasioptical Beam Combiner

Cryostat

Feed horn antennas

Phase Shifters

45° CW twist rectangular wave guide

45º CCW twist rectangular wave guide

Bolometer Array

Parabolic mirror

interference pattern

1 baseline

1 baseline

1 baseline

total signal

1 horn

Interference pattern
  • The interference pattern is imaged on the bolometer array
  • Each pixel measures a linear combination of all visibilities with different phase shifts
  • Sequences of phase shift modulations allow reconstruction of all visibilities in optimal way
  • In a close-packed array, many baselines are redundant - these need to be ‘co-added’

[Charlassier et al., arxiv:0806.0380, A&A 497 (2009) 963]

[Hyland et al., arXiv :0808.2403v1, MNRAS 393 (2009) 531]

sensitivity comparison to imager
Sensitivity - comparison to imager

Both systems have:

  • 256 horns
  • 1 angular resolution
  • background-limited bolos
  • 25 % bandwidth

Interferometer:

  • co-adds ‘redundant’ visibilities
  • has 1000 detectors

data pts from

simulation

[Hamilton et al., arxiv:0807.0438, A&A 491-3 (2008) 923-927] updated with bandwidth and accurate NET calculations]

the millimeter wave bolometric interferometer mbi 4

Fizeau (optical) beam combiner

  • 4 feedhorns (6 baselines)
  • 90 GHz (3 mm)
  • ~1o angular resolution
  • 7o FOV

Antennas

Phase modulators

The Millimeter-Wave Bolometric Interferometer (MBI-4)

Liquid nitrogen tank

Liquid helium tank

Secondary mirror

3He refrigerator

Primary mirror

Bolometer unit

mbi assembly
MBI Assembly

15 cm

19 spider-web bolos (JPL)

(PSB’s not required)

mbi 4 at pine bluff observatory madison wi

MBI-4 at Pine Bluff ObservatoryMadison, WI

  • First light March 2008
  • Beam maps March 2009
  • See poster by Amanda Gault
mbi 4 interference fringes
MBI-4 interference fringes

Observed Signal (Bolometer #9)

Simulated Signal

  • Baseline formed by horns 2 and 3
  • Observed Gunn oscillator on tower
slide17

The QUBIC collaboration

University of Wisconsin USA

A merging of MBI (USA) with BRAIN (Europe)

IAS Orsay France

CSNSM Orsay

France

University of Richmond USA

Maynooth University Ireland

APC Paris France

Brown University USA

Universita di Milano-Bicocca Italia

IUCAA, Pune India

La Sapienza, Roma, Italia

Manchester University UK

CESR Toulouse France

QU Bolometric Interferometer for Cosmology

Google Maps

the qubic instrument concept

phase shifters

horns

Bolometer array

The QUBIC instrument concept

Sky

~25 cm

  • Off-axis quasi-optical beam combiner

4K

4K

4K

back

horns

4K

~60 cm

~40 cm

4K

~10 cm

Cryostat

300 mK

~70 cm

qubic design

Primary (entry) horns

QUBIC (144x6,

(

Secondary (reemitting) horns

Significance

QUBIC Design

~ 25cm

6 modules of 144 entry horns

  • 14 deg. primary beams
  • square compact configuration
  • multipole range : 25-150
  • ~900 TES bolometers / module
  • ~10000 baselines / module
  • phase switch redundant baselines simultaneously

- phase steps of 15 degrees

- sequence length ~500 steps

3 channels: 90,150,220 GHz

25% Bandwidth

Modular Cryogenics

  • One 4K pulse tube for 6 modules
  • 100 mK focal plane

r ~ 0.01 in one year of data

qubic program
QUBIC program

2006

MBI-4

BRAIN

Pathfinder

2007

  • MBI-4 Prototype
    • 4 horns bolometric interferometer
    • works in Wisconsin (2008 and 2009)
    • Fringes observed !
  • BRAIN Pathfinder
    • Site testing, logistics
    • Atmosphere characterization at Dome C
    • (effective temperature, polarization ...)
      • 2 campaigns, January 2006 and 2007
      • Third campaign starting next Antarctic summer
  • QUBIC
    • Search for primordial B-modes (50 < l < 150)
    • 6 Bolometric interferometer modules
    • 144 horns/module (90, 150, 220 GHz)
    • 25% Bandwidth
    • Full instrument in 2012-2013
    • Target : r ~ 0.01 in 1 year of data

2008

2009

2010

QUBIC

first module

2011

QUBIC

2012

next steps for bolometric interferometry
Next steps for Bolometric Interferometry
  • phase modulators are critical
      • multiple phase states (~ 5 bits)
      • 1 ms switching speed
      • several technologies under study: Faraday, MEMs, s/c nanobridge switches, varactor diode
  • simulations of systematic effects, scan strategies
  • foreground removal in visibility space
  • QUBIC
  • see poster by T.K. Sridharan for alternate BI approach