Context: Planck & B-pol Polarized foregrounds The PILOT experiment J.-Ph. Bernard CESR Toulouse PILOT balloon experiment J.-Ph. Bernard, CNES CCT, Toulouse,

• Context: Planck & B-pol • Polarized foregrounds• The PILOT experiment

J.-Ph. Bernard CESR Toulouse

PILOT balloon experiment

J.-Ph. Bernard, CNES CCT, Toulouse, Nov. 15th 2006

PILOT:Science Objectives

• Observe the linear polarization of dust emission in order to :- Reveal the structure of the magnetic field which controles the structuration of theInterstellar medium and the collapse leading to the formation of new stars

- The nature of dust grains through their geometric and magnetic properties• Understand the polarized foreground for future CMB polarized missionsAn accurate subtraction of this foreground emission will require a deep understandingof its origin. It also requires detection of dust polarization in faint diffuse cirrus clouds.

These objectives require high sensitivity and fast mappingand therefore the use of bolometer filled arrays.

Polarized Instrument for Long-WavelengthObservations of the Tenuous ISM

http://pilot.cesr.fr J.-Ph. Bernard, CNES CCT, Toulouse, Nov. 15th 2006

PILOT:Consortium

France:CESR Toulouse (J.P. Bernard, C. Marty)IAS Orsay (B. Leriche)CEA Saclay (L. Rodriguez)CNES Toulouse (Div ballon)Europe:ESTEC Netherlands: (J. Tauber, G. Pilbrat)Cardiff U. UK (M. Griffin, P. Hargrave)Manchester U. UK (B. Maffei)Roma Italy (S. Masi, P. deBernardis)


Azimuth scanning

Elevationchange

PILOT:Description

Photometer

Primary miror

Stellar sensor

CNES gondola


Characteristics

Instantaneous FOV: 46'*23'


FIR/submm Planck

Planck should allow to detect -variations of the dust polarization(at 3- every 1° below Av=0.5 mag).

Detecting more precisely smaller variations toward more diffuse clouds may require using a polarized instrument at higher frequency like PILOT

Planck: unpolarized

Planck: polarized


Planck: unpolarized

PILOT

Planck: polarized

PILOT vs Planck -coverage


Gondola : « standard » CNES (LPMA/IASI), about 500kg Rotation in azimut allowing scans on the skyTelescope : = 1m, off-axis Gregorian. Angular resolution = 3’ @ 550 mStellar sensor : large format CCD. Scanning sky at 1.5°/s. hopefuly day/night.Photometer :

- 2 photometric chanels @ 240 m and 550 m- Detectors cooled down to 300 mK

PILOT:Description


PILOT: Optics

Telescope:-off-axis parabolic primary mirror (M1)-off-axis ellipsoid secondary mirror (M2)-Mitsugushi-Dragone config.

Reimaging Optics:-Two lenses (L1 & L2).-Lyot stop (L).-Half-wave plate (WP).-Telecentric objective config.-WP and L next to a pupil (image of M1) of the optics.- Polar analysis grid (G)


PILOT:Detectors


0.3 K

PILOT:Detectors


Bolometer arrays developped by CEA/LETI for Herschel/PACS

multiplexed readoutNEP = 2 10-16 W/Hz-1/2

16*16 pixels

PILOT:Detectors

InterconnectionCircuit

Thermometer

Silicon Grid+ Absorber

ReflectorIndium Bumps


PILOT will have a total of2048 individual bolometers !!(to be compared with less than 100 for previous instruments)

Principle of the polarization measurement with PILOT

Bi-refringent material1/2 wave plate

input linear polarization

Grid analyzer

Transmission detector

Reflection detector

Polarization Measurement



input linear polarization

Grid analyzer

Transmission detector

Reflection detector



Bi-refringent material1/2 wave plate


• Most existing experiments rotate the HWP at constant velocity and detect modulated signal on detectors.• For PILOT, we change HWP positions by discrete steps because:1/ we do not want to modulate even a tiny fraction of the background(background is 104 times the scientific signal, ie 106 times the polarization)2/ sky mapping while spinning would be too fast for the available detectors.





PILOT: scanning strategy

Azimuth

Elevation

550

m

240

mJ.-Ph. Bernard, CNES CCT, Toulouse, Nov. 15th 2006

For one position of the waveplate, one measures :

At least 2 positions are needed to measure I, Q, U

Q,U derived from differencesI measured from average

(Transmission array)

(Reflection array)



Wave-plate angle"Paralactic" angleInstrumental rotation



PILOT:Calibration Source

No unpolarized calibration source on sky

Internal calibration source=Spare of the Herschel SPIRE calibration source

- Very accurate repeatability- Fast on/off switch- Low consumption- Used to calibrate Response flat-field


PILOT: Sensitivity

Results : Galactic plane 30 mn observations @ 240 m, 250 �/hr

Input Intensity Recovered Intensity Polarization (%)

Max=6%(Red)

Min=4%(blue)


Simulations

Results : Cirrus (Av=2 mag) 1hr observations @ 240 m, 16 �/hr

Input Intensity Recovered Intensity Polarization (%)

Max=3%(Rouge)

Min=8%(bleu)

J.-Ph. Bernard, PILOT CNES review, Toulouse, March 13th 2006

Mission Planning

• Objective on astronomical targets- Galactic plane survey- Deep field on cirrus clouds- Large and Small Magellanic Clouds

• Source visibility requires combination of 3 flights from different launch sites (different latitudes)

• Preliminary study with:- Kiruna - Sweeden (lat = 60°, flight #1, winter 2008)-Trapani - Italy (lat=38°, flight#2, summer 2009)-Alice-Spring or Sao-Jose-Dos Campos- Brazil (lat = -23°, flight#3, spring 2010)

• Simulations performed with realistic parameters:- mapping speed: 300°2/h- vscan=24'/s- scan amplitude=20°

• Observational constraints:- 20° < elevation < 60°- night-time observations only


~ 90% of the Galactic plane is surveyed within a 20- 25 hrs total integration time 12 to 16 hrs left for others tagets (Cirrus, Magellanic clouds, calibration…)

We insist on the fact that it would be much more convenient and safe for the scientific return of each flight to be able to observe during day-time, even though it is not formally required. -> a day-operating stellar sensor would be a goal to reach for the two last flights.

Kiruna Trapani AliceSpring Sao-Jose

Mission Planning


The END

PILOT

http://pilot.cesr.fr

• PILOT will attempt at measuring the linear polarization from dust emission in our Galaxy to very high accuracy levels at high frequencies• The goal is to understand the physics of dust polarization, to ultimately help with component separation for future cosmology missions• PILOT is a test-bed for the use of compact multiplexed bolometer arrays for polarization measurements• PILOT is funded by CNES. Detailed definition is ending and realization of the instrument is starting. • First flight expected in end-2008 (Kiruna)


The END

PILOT is the pilot fishFuture CMB-pol mission ?

PILOT

http://pilot.cesr.fr J.-Ph. Bernard, CNES CCT, Toulouse, Nov. 15th 2006

• PILOT will attempt at measuring the linear polarization from dust emission in our Galaxy to very high accuracy levels at high frequencies• The goal is to understand the physics of dust polarization, to ultimately help with component separation for future cosmology missions• PILOT is a test-bed for the use of compact multiplexed bolometer arrays for polarization measurements• PILOT is funded by CNES. Detailed definition is ending and realization of the instrument is starting. • First flight expected in end-2008 (Kiruna)

CMB Anisotropy/Polarization map from B2K (2003)

BOOMERanG-FG• We plan to re-fly B03 with an

upgraded forcal plane, to go after foreground cirrus dust polarization.

• This information is essential for all the planned B-modes experiments (e.g. BICEP, Dome-C etc.) and is very difficult to measure from ground.

• The BOOMERanG optics can host an array of >100 PSB at >350 GHz.

140 GHzPSB

240 GHz340 GHz

340 GHzPSB

140 GHzPSB

BOOMERanG-03

BOOMERanG-FG

Frequency range complementary to PILOT (higher f. J.F. Bernard, Toulouse)

From C. Lawrence, PoS (CMB2006) 012

Documents

Context: Planck & B-pol Polarized foregrounds The PILOT experiment J.-Ph. Bernard CESR Toulouse PILOT balloon experiment J.-Ph. Bernard, CNES CCT, Toulouse,