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{{About|an astronomical instrument|the Pokémon|List of generation V Pokémon#Archeops{{!}}List of generation V Pokémon}}
[[Image:Archeops gondala at launch.jpg|thumb|250px|right|The gondola being launched]]
{{Infobox Telescope}}
'''Archeops''' is a balloon-borne instrument dedicated to measure the [[Cosmic microwave background]] (CMB) temperature anisotropies.
It'''Archeops''' aimedwas ata measuringballoon-borne theinstrument cosmicdedicated backgroundto emittedmeasuring justthe after[[Cosmic themicrowave Bigbackground]] (CMB) temperature Banganisotropies. The study of this radiation is essential to obtain precise information on the evolution of the [[Universe]]: density, [[Hubble's law#Measured values of the Hubble constant|Hubble constant]], [[Age of the universe|age of the Universe..]], etc. To achieve this goal, measurements have beenwere done with devices cooled down at 100mK temperature placed at the focus of a warm telescope. To avoid atmospheric disturbance the whole apparatus is placed on a gondola below a helium balloon that reaches 40  km altitude.▼
 
Archeops has four bands in the millimeter domain (143, 217, 353 and 545  GHz) with a high angular resolution (about 15 arcminutes) in order to constrain small anisotropy scales, as well as a large sky coverage fraction (30%) in order to minimize the intrinsic cosmic variance.▼
▲It aimed at measuring the cosmic background emitted just after the Big Bang. The study of this radiation is essential to obtain precise information on the evolution of the Universe: density, Hubble constant, age of the Universe... To achieve this goal, measurements have been done with devices cooled down at 100mK temperature placed at the focus of a warm telescope. To avoid atmospheric disturbance the whole apparatus is placed on a gondola below a helium balloon that reaches 40 km altitude.
 
== Instrument and flights ==▼
▲Archeops has four bands in the millimeter domain (143, 217, 353 and 545 GHz) with a high angular resolution (about 15 arcminutes) in order to constrain small anisotropy scales, as well as a large sky coverage fraction (30%) in order to minimize the intrinsic cosmic variance.
The instrument was designed by adapting concepts put forward for the High Frequency Instrument of [[Planck Surveyor|Planck surveyor]] (Planck-HFI) and using balloon-borne constraints.<ref>{{cite journal|last=Benoît|first=A.|display-authors=etal|year=2002|title=Archeops: A High Resolution, Large Sky Coverage Balloon Experiment for Mapping CMB Anisotropies|journal=[[Astroparticle Physics (journal)|Astroparticle Physics]]|volume=17|issue=2|pages=101–124|arxiv=astro-ph/0106152|bibcode=2002APh....17..101B|doi=10.1016/S0927-6505(01)00141-4}}</ref>
Namely, it consists of an open 3He-4He dilution cryostat cooling spiderweb-type [[bolometer]]s at 100 mK; cold individual optics with horns at different temperature stages (0.1, 1.6, 10 K) and an off-axis [[Gregorian telescope]].
 
The CMB signal is measured by the 143 and 217 &nbsp;GHz detectors while interstellar dust emission and atmospheric emission are monitored with the 353 (polarized) and 545 &nbsp;GHz detectors.▼
The whole instrument is baffledbaffled so as to avoid stray radiation from the Earth and the balloon. ▼
 
To cover as far as 30% of the sky, the payload was spinning mostly above the atmosphere, scanning the sky in circles with a fixed elevation of roughly 41 degrees. The gondola, at a floatfloat altitude above 32 &nbsp;km, spins across the sky at a rate of 2 rpm which, combined with the Earth rotation, produces a well sampled sky at each frequency.▼
▲== Instrument ==
<!-- [[Image:Archeops sky coverage.jpg|thumb|300px|right|Sky coverage is 30%]] -->
The instrument was designed by adapting concepts put forward for the High Frequency Instrument of [[Planck_Surveyor | Planck surveyor]] (Planck-HFI) and using balloon-borne constraints [Benoît et al. 2002]<ref>A. Benoit et al., 2002, Astropart. Phys. 17 101-124 ([http://arxiv.org/abs/astro-ph/0106152 preprint])</ref>.
Namely, it consists on
* an open 3He-4He dilution cryostat cooling spiderweb-type [[bolometer]]s at 100 mK
* cold individual optics with horns at different temperature stages (0.1, 1.6, 10 K)
* an off-axis Gregorian telescope.
 
▲The CMB signal is measured by the 143 and 217 GHz detectors while interstellar dust emission and atmospheric emission are monitored with the 353 (polarized) and 545 GHz detectors.
▲The whole instrument is baffled so as to avoid stray radiation from the Earth and the balloon.
 
To cover as far as 30% of the sky, the payload was spinning mostly above the atmosphere, scanning the sky in circles with a fixed elevation of roughly 41 degrees.
▲The gondola, at a float altitude above 32 km, spins across the sky at a rate of 2 rpm which, combined with the Earth rotation, produces a well sampled sky at each frequency.
 
 
== Flights ==
Archeops flew for the first time in Trapani (Sicily) with four–hours integration time.
 
Then, the upgraded instrument was launched three times from the Esrange base near Kiruna (Sweden) by the CNES during 2 consecutive Winter seasons (2001 and 2002).
 
The last and best flight on Feb. 7th, 2002 yields 12.5 hours of CMB–type data (at ceiling altitude and by night) from a 19–hours total. The balloon landed in Siberia and it was recovered (with its precious data recorded on–board) by a Franco–Russian team with –40 deg.C. weather.▼
 
▲Archeops flew for the first time in Trapani (Sicily) with four–hours integration time. Then, the upgraded instrument was launched three times from the Esrange base near Kiruna (Sweden) by the CNES during 2 consecutive Winter seasons (2001 and 2002). The last and best flightflight on Feb. 7th, 2002 yields 12.5 hours of CMB–type data (at ceiling altitude and by night) from a 19–hours total. The balloon landed in Siberia and it was recovered (with its precious data recorded on–board) by a Franco–Russian team with –40 deg.°C. weather.
 
== Results ==
<!-- [[Image:Archeops last flight map.jpg|thumb|300px|right|Archeops CMB map]] -->
Archeops has linked, for the first time and before [[WMAP]], the large angular scales (previously measured by [[Cosmic Background Explorer|COBE]]) to the first acoustic peak region [Benoît et al. 2003]<ref>{{cite journal|last=Benoît|first=A.|display-authors=etal|year=2003|title=The BenoitCosmic etMicrowave al.,Background 2003,Anisotropy Power A&ASpectrum 399measured L19by (Archeops|journal=[http://[Astronomy and Astrophysics]]|volume=399|issue=3|pages=L19|arxiv.org/abs/=astro-ph/0210305 preprint])|bibcode=2003A&A...399L..19B|doi=10.1051/0004-6361:20021850}}</ref> and [Tristram et al. 2005]<ref>{{cite journal|last=Tristram|first=M.|display-authors=etal|year=2005|title=The Tristram,CMB G.temperature Patanchon,power J.spectrum F.from Macías-Pérez,an etimproved al.,analysis of 2005,the A&AArcheops data|journal=[[Astronomy and Astrophysics]]|volume=436 |issue=3|pages=785 ([http://|arxiv.org/abs/=astro-ph/0411633 preprint])|bibcode=2005A&A...436..785T|doi=10.1051/0004-6361:20042416}}</ref>.
 
From its results, inflation motivated cosmologies have been reinforced with a flat Universe (total energy density Ω<sub>tot</sub> = 1 within 3 %).
When combined with complementary cosmological datasets regarding the value of Hubble's constant, Archeops gives constraints on the dark energy density and the baryonic density in very good agreement with other independent estimations based on supernovae measurements and big bang nucleosynthesis (see [Benoît et al. 2003]<ref>{{cite journal|last=Benoît|first=A.|display-authors=etal|year=2003|title=Cosmological Benoitconstraints etfrom al.,Archeops|journal=[[Astronomy 2003, A&Aand Astrophysics]]|volume=399 |issue=3|pages=L25 ([http://|arxiv.org/abs/=astro-ph/0210306 preprint])|bibcode=2003A&A...399L..25B|doi=10.1051/0004-6361:20021722}}</ref>)
 
Archeops has given the first and still unique polarized maps of the galactic dust emission with this resolution [Benoît et al. 2004]<ref>{{cite journal|last=Benoît|first=A.|display-authors=etal|year=2004|title=First BenoitDetection etof al.,Polarization 2004,of A&Athe 424Submillimetre 571Diffuse Galactic Dust Emission by (Archeops|journal=[http://[Astronomy and Astrophysics]]|volume=424|pages=571|arxiv.org/abs/=astro-ph/0306222 preprint])|bibcode=2004A&A...424..571B|doi=10.1051/0004-6361:20040042}}</ref> and [Ponthieu et al. 2005]<ref>{{cite journal|last=Ponthieu|first=N.|display-authors=etal|year=2005|title=Temperature Ponthieu,and J.polarization F.angular Macías-Pérez,power M.spectra Tristramof etGalactic al.,dust radiation 2005,at A&A353 444GHz 327as (measured by Archeops|journal=[http://[Astronomy and Astrophysics]]|volume=444|issue=1|pages=327|arxiv.org/abs/=astro-ph/0501427 preprint])|bibcode=2005A&A...444..327P|doi=10.1051/0004-6361:20052715}}</ref>.
 
 
==References==▼
<references/>
 
 
==See also==
*[[Cosmic microwave background experiments]]▼
*[[Observational cosmology]]
 
 
==External links==
*[http://www.archeops.org/ Archeops Homepage]
 
▲== References ==
{{commons category|Archeops}}
{{Reflist}}
 
{{CMB experiments}}
 
[[Category:Astronomical instruments]]
{{physics-stub}}
▲*[[Category:Cosmic microwave background experiments]]
{{astronomy-stub}}
[[Category:Balloon-borne telescopes]]
 
[[fr:Archeops]]
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