QUBIC: a Fizeau i.........er targeting primordial B

Transcript

QUBIC: a Fizeau i.........er
targeting primordial
B-modes
A.Tartari (APC and PCCP Paris)
[email protected]
Universita degli Studi di Milano - Dipartimento di Fisica, 23 maggio 2014
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QUBIC
Collaboration
QUBIC Collaboration
APC Paris, France
IAS Orsay, France
CSNSM Orsay, France
IRAP Toulouse, France
Maynooth University, Ireland
Università di Milano-Bicocca, Italy
Università degli studi, Milano, Italy
Università La Sapienza, Roma, Italy
University of Manchester, UK
IHEP, Beijing, China
NIAOT, Nanjing, China
PMO, Nanjing, China
Richmond University, USA
Brown University, USA
University of Wisconsin, USA
arXiv:1010.0645 ~ Astroparticle Physics 34 (2011) 705–71
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Summary
1. Scientific context (after March the 17th...)
2. QUBIC global view: Fizeau Interferometry
3. Subsystems
4. Deployment schedule and perspectives
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Dipartimento di Fisica - UNIMI
MIlano, Italy, May 23rd ,2014
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-
-
m
d
t
t
e
Inflation leaves peculiar imprints on the polarized CMB sky
a.
b.
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c.
[ l(l+1)Cl/2π ]1/2 (µK)
d
s
Scientific Context
d.
102
101
ΘΘ
EE
1
g. lensing
10-1
BB
2.6
g. waves
10-2
3.2
10
100
x10 15
x10
16
Ge
V
detected by SPT team, july 2013
GeV
1000
l
FIG. 2: Scalar CMB power spectra in temperature (ΘΘ) and
Monday
26 May polarization
14
E-mode
(EE) compared with B-mode polariza-
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Scientific Context
The CMB polarization after BICEP2
A fundamental discovery made possible by a quantum jump in
sensitivity (arXiv:1403.3985v2). Waiting for Keck Array.
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Scientific Context
with BICEP2 a new insight on Inflation is possible
•
•
Scalar perturbations:
•
Density fluctuations
•
•
•
Temperature
E polarization
No B polarization
Tensor perturbations:
•
•
Specific prediction from inflation!
Primordial gravitational waves
•
•
•
Temperature
E polarization
B Polarization
Einf ~
16
2x10
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GeV
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Scientific Context
Experiments: a technology-inspired landscape
(incomplete)
An impressive list of experiments (deployed, under construction, or
proposed) targeting r~few 10-2 from ground or balloon.
Imagers modulated on top of imaging optics: ABS,
PIPER, CLASS...
High-throughput: SWIPE on LSPE, MuSE
Correlation Polarimeters: STRIP on LSPE
Interferometry: QUBIC
Instrumental systematics potentially very different
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QUBIC: principles
Different ways for interferometry
Heterodyne
(ALMA...)
Intensity
Interferometry (VLBI)
correlate fields
correlate intensities
Adding Interferometry
Two-beams (Michelson)
correlate fields
correlate fields
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Multiple-beams
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QUBIC: principles
QUBIC: a Fizeau bolometric interferometer
+"
S=G|E1+E2+…En|2"
All-to-one (or Fizeau): each detector integrates the power delivered by a linear combination of
all the antenna signals
Planar interferometer: all the antenna apertures lie on the same plane, within a single
telescope mount (e.g.: DASI)
A modulation stage must be included to control systematics
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QUBIC: principles
How do you make an “all-to-one”?
antennas
modulator
combiner
Corrugated
horns
rotating HWP
phase shifters
MBI-4: Tucker et al. SPIE 2008
optical
reflective
waveguided
refractive
DIBO: Ghribi et al. IJIMTW 2010
detectors
TES
MKIDs
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QUBIC: principles
Battistelli et al. Astropart. Phys. 34 2011
97, 150 and 220 GHz
~40 cm
Sky
Filters
Rotating HWP
primary horns
switches (WG shutters)
Cold box
secondary horns
Y polarization
bolometer
array
Polarizing grid
Cryostat
X polarization bolometer
array
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QUBIC: principles
Families of parallel rays (same color) hit the same detector
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QUBIC: principles
QUBIC as a synthetic imager
Useful point of view:
Fact: horns are diffractive apertures that makes a spatial
filtering at the level of the system pupil.
Consequence:
- QUBIC as an imager accepting only a sub-set of those modes
that would be collected by our beam combiner used as a
telescope.
- If it is an imager: we scan the sky, make maps and get Cℓ(P.Chanial
et al., in preparation)
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QUBIC: principles
An equivalent point of view:
a. The beam combiner alone can be used as a telescope (uniformly illuminated
pupil) accepting N~FOV/(λ/D)2 Airy spots.
b. Horns are diffractive (single-mode) apertures that make spatial filtering. The
entrance pupil is an array of gaussian-illuminated apertures, whose far-field
pattern, produced by the telescope, is QUBIC synthetic beam.
c. On a given focal plane pixel, the synthetic image is the convolution of sky
signal (Q,U) and synthetic beam
p
X={Q,U} and B s is the synthetic beam at pixel p
d. HWP
!
!
!
!
R(d p ,t) = SI (d p ) ± cos[4Φ(t)]SQ (d p ,t) ± sin[4Φ(t)]SU (d p ,t)
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QUBIC: principles
Equivalent to digital filtering of an image
(Wiener-Khinchin)
Kernel
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QUBIC: principles
Aperture
Far Field
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QUBIC: principles
(including detector finite size and 30% BW)
8.5 deg.
FWHM
0.54 deg.
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QUBIC: principles
only main synth lobe
P.Chanial et al., in preparation
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QUBIC: principles
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QUBIC: principles
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QUBIC: principles
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QUBIC: principles
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QUBIC: principles
Need to use the full synthetic beam!
AΩ ≅ λ
2
@150 GHz
from M. De Petris
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QUBIC: principles
The window function of QUBIC 150 GHz
400 horns - 14 deg. FHWM - 150 GHz
Window function (arbitrary units)
2.0
No BW - No detector size
No BW - 3 mm detector
25% BW - No detector size
25% BW - 3 mm detectors
S/N ratio : 25% BW - No detector size
S/N ratio : 25% BW - 3 mm detectors
1.5
1.0
0.5
0.0
0
100
200
300
400
500
multipole
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QUBIC: principles
FIRST END-TO-END SIMULATION (P.Chanial, JC Hamilton)
TOD
MAPS
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SPECTRA
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QUBIC: principles
Self-calibration
Bigot-Sazy et al. A&A 550 (2013)
Baselines are redundant. Same Fourier mode realized by different
horn pairs.
Switches (shutters) allow to study a baseline at a time.
Ideally they should give the same pattern on the focal plane. If
they do not, it is because of systematics.
★ External polarized calibration source
★ The longer the integration time we spend on each baseline, the more precise the
determination of systematics, the more accurate the polarized power spectra (see
later)
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QUBIC: principles
Self-calibration
Example: obtain real horn positions
nominal
real
real
after SC
S.-C.
NB: We can recover gain unbalancing and cross-pol leakage through all our detection chain
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QUBIC: principles
Self-calibration
"
ℓ = 2π u
~50 (shortest baseline)
~900 longest (1 sample!)
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QUBIC: principles
Self-calibration
Jones Matrix residual error
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Accuracy on systematics estimations is
only limited by statistics
-2
10-3
10-4
10-5
10-6
1
102
104
106
Time spent on each baseline (s)
"
ℓ = 2π u
~50 (shortest baseline)
~900 longest (1 sample!)
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QUBIC: principles
Self-calibration
Impact of self-cal on CMB systematics
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QUBIC: principles
Self-calibration
100
10-1
CBB for r=0.05 (QUBIC Target)
QUBIC
range
CEE
leakage
without self-calibration
CEE leakage with self-calibration (2.5% of observation time)
l(l+1)Cl/2π) [µK2]
initial E➜B
leakage
10-2
10-3
Self-Calibration
E
nal
g
i
s
d
e
xpect
05)
(r=0.
residual E➜B
leakage
10-4
10-5
10
100
ell
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Monday 26 May 14
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QUBIC: principles
Self-calibration
100
10-1
e.g.:Q/U mixing control
QUBIC
range
CEE
leakage
l(l+1)Cl/2π) [µK2]
initial E➜B
leakage
10-2
10-3
Self-Calibration
E
nal
g
i
s
d
e
xpect
05)
(r=0.
residual E➜B
leakage
10-4
10-5
10
100
ell
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QUBIC: principles
Self-calibration
100
10-1
Needs:
e.g.:Q/U mixing control
• Active calibration source
• Far-field (~50m), elevation > 30 deg.
• Power ~ 1nW per horn
QUBIC
range
CEE
leakage
•
•
l(l+1)Cl/2π) [µK2]
initial E➜B
leakage
10-2
10-3
Self-Calibration
E
nal
g
i
s
d
e
xpect
05)
(r=0.
Solution:
Synthesizer 130-168 GHz, 5mW, 14.5
deg. FWHM
Tour de 45m à 45m de QUBIC
residual E➜B
leakage
10-4
10-5
10
100
ell
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QUBIC: first module
QUBIC first module
● Frequency: 150 GHz
● Bandwidth 25% (more than 30 GHz)
● Number of back-to-back horns: 400
● Number of detectors: 2048 (2 focal planes)
● Combiner: off-axis Gregorian telescope with f/# =0.7
● Shortest baseline: 14 mm (multipoleℓ~ 40); longest baseline:
300 mm (multipoleℓ~ 900).
● Cosmology in the range ℓ~30 up to ~150 (a primordial B-mode
window).
● Polarization basis: linear {ex,ey}, fixed by the wire-grid
● Accessible Stokes visibilities: I, Q and U (linear basis+HWP)
NB: currently it is practically unfeasible to correlate 400 antennas over
30 GHz bandwidth with standard interferometric techniques
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QUBIC: first module
The First Module at 150 GHz
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QUBIC: first module
First module: subsystems
The global view of the experiment and the choice of devices are frozenFor
each subsystem there is a clear technological solution developed
within the collaboration (see Ghribi et al., arXiv:1307.5701v1).
Design and dimensioning of each part is practically concluded.
Tolerancing is in progress (e.g.: mounting of mirrors, etc...).
IU
5
752 : latoT
7
UI
Wafer: 3"
QS
SQ
5
7
9
11
12
13
14
16
15
16
17
18
17
18
18
18
I
18
15
U
SQ
81
81
81
71
81
81
61
71
51
61
31
51
21
41
7
11
5
9
752 : latoT
28
mm2.0 + mm3 :soloB
"3 :refaW
UI
SQ
S
"3 :refaW
mm2.0 + mm3 :soloB
I
Bolos: 3mm + 0.2mm
9
11
21
31
51
41
QS
Q
IU
Bolos: 3mm + 0.2mm
Wafer: 3"
SQ
U
Monday 26 May 14
IU
Total : 257
U
SQ
51
61
61
71
71
81
81
81
81
18
18
18
18
18
17
17
16
16
15
15
14
13
12
11
9
7
5
Total : 257
I
81
250 pixels
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QUBIC: Subsystems
Dielectrically Embedded Mesh HWP: Lerner type
G. Pisano et al. in press in PIER M (2012)
Half-wave plate
Corrugated horn arrays
∅=20cm
Critical issues to be investigated:
• Slight expected difference in absorption between the waveplate axes
Detectors: NbSi TES
Beam combiner
• The potential gradient in temperature across large plates
+ TD Multiplexing, D.Prêle et al. JLTP 2014
Gayer et al. SPIE 2012
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QUBIC: the site - Dome C
Tomasi et al. JGR 2011
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QUBIC: The site
3 Considerations (to resume)
The Bolometric Interferometry is a technique whose conceptual aspects
has been progressively understood during the last 10 years:
a. coherent summation of equivalent baselines
b. BI as a synthetic imager (scanning the sky!)
c. self-calibration and systematics control (see also Karakci et al. ApJS 2013)
The design of QUBIC first module (150 GHz) is at an advanced stage: all the
subsystems have been dimensioned. No major technological obstacles do exist.
The observational site (Dome C) has been demonstrated to be an excellent
site for CMB (Battistelli et al. MNRAS 2011).
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Scientific Context
Perspectives/Comments
Major ideas in exp. techniques
Major Science
credit: C.Pryke, Moriond 2014
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Scientific Context
a. Within ~few years new detections might be announced: e.g. by
Planck, Polarbear, ACTpol, SPTpol...
b. Between E-mode detection (DASI) and QUAD EE power
spectra a lapse of time of ~6 years occurs.
c. A similar scenario might be in front of us. Need more
experiments from ground and balloon (different techniques,
different patches of sky) to consolidate BICEP2 discovery. And
maybe space.
d. QUBIC, a partially funded experiment, relies on a fascinating (and
unique) concept. If fast, it can play role in the field.
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Scientific Context
1. Scanning strategy: in progress
2.QUBIC 150 GHz - can perform better than BICEP2
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“There is no point in attempting a half-hearted experiment
with an inadequate apparatus” R.H. Dicke
END
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Monday 26 May 14
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QUBIC: a Fizeau i.........er targeting primordial B

Transcript

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