The Micromegas detector of the CAST experiment

Abbon, P.; Andriamonje, S.; Aune, S.; Dafní, T.; Davenport, M.; Delagnes, É.; Oliveira, Rui de; Fanourakis, G.; Ribas, E. Ferrer; Franz, J.; Geralis, T.; Giganon, A.; Gros, M.; Giomataris, Y.; Irastorza, I.G.; Kousouris, K.; Morales, J.; Papaevangelou, T.; Ruz, J.; Zachariadou, K.; Zioutas, K.

doi:10.1088/1367-2630/9/6/170

Cited by 68 publications

(81 citation statements)

References 17 publications

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“…The use of small Micromegas TPCs as x-ray detectors in the CAST experiment dates back to 2003 and it is indeed a pioneer use of Micromegas in a rare event search [23]. This early work did motivate the later T-REX development whose results are here reviewed.…”

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confidence: 98%

Gaseous time projection chambers for rare event detection: results from the T-REX project. II. Dark matter

Irastorza

Aznar

Castel

et al. 2016

J. Cosmol. Astropart. Phys.

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Abstract. As part of the T-REX project, a number of R&D and prototyping activities have been carried out during the last years to explore the applicability of gaseous Time Projection Chambers (TPCs) with Micromesh Gas Structures (Micromegas) in rare event searches like double beta decay, axion research and low-mass WIMP searches. While in the companion paper we focus on double beta decay, in this paper we focus on the results regarding the search for dark matter candidates, both axions and WIMPs.

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mentioning

confidence: 98%

Gaseous time projection chambers for rare event detection: results from the T-REX project. II. Dark matter

Irastorza

Aznar

Castel

et al. 2016

J. Cosmol. Astropart. Phys.

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“…During this long experimental programme, CAST has used a variety of detection systems at both magnet ends, including a multiwire time projection chamber 25 , several Micromegas detectors 26 , a low-noise charged coupled device attached to a spare X-ray telescope (XRT) from the ABRIXAS X-ray mission 27 , a γ -ray calorimeter 21 , and a silicon drift detector 23 .…”

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confidence: 99%

New CAST limit on the axion–photon interaction

2017

Nature Phys

843

709

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Hypothetical low-mass particles, such as axions, provide a compelling explanation for the dark matter in the universe. Such particles are expected to emerge abundantly from the hot interior of stars. To test this prediction, the CERN Axion Solar Telescope (CAST) uses a 9 T refurbished Large Hadron Collider test magnet directed towards the Sun. In the strong magnetic field, solar axions can be converted to X-ray photons which can be recorded by X-ray detectors. In the 2013-2015 run, thanks to low-background detectors and a new X-ray telescope, the signal-to-noise ratio was increased by about a factor of three. Here, we report the best limit on the axion-photon coupling strength (0.66 × 10 −10 GeV −1 at 95% confidence level) set by CAST, which now reaches similar levels to the most restrictive astrophysical bounds.A dvancing the low-energy frontier is a key endeavour in the worldwide quest for particle physics beyond the standard model and in the effort to identify dark matter 1,2 . Nearly massless pseudoscalar bosons, often generically called axions, are particularly promising because they appear in many extensions of the standard model. They can be dark matter in the form of classical field oscillations that were excited in the early universe, notably by the re-alignment mechanism 3 . One particularly well motivated case is the quantum chromodynamics (QCD) axion, the eponym for all such particles. The existence of this new lowmass boson follows from the Peccei-Quinn mechanism as an explanation why QCD is perfectly time-reversal invariant within current experimental precision 3 .Axions were often termed 'invisible' because of their extremely feeble interactions, yet they are the target of a fast-growing international landscape of experiments. Numerous existing and foreseen projects assume that axions are the galactic dark matter and use a variety of techniques that are sensitive to different interaction channels and optimal in different mass ranges 4 . Independently of the dark-matter assumption, one can search for new forces mediated by these low-mass bosons 5 or the back-reaction on spinning black holes (superradiance) 6 . Stellar energy-loss arguments provide restrictive limits that can guide experimental efforts, and in some cases may even suggest new loss channels 3,7,8 .The least model-dependent search strategies use the production and detection of axions and similar particles by their generic twophoton coupling. It is given by the vertex L aγ = −(1/4) g aγ F µν F µν a = g aγ E · B a, where a is the axion field, F the electromagnetic field-strength tensor, and g aγ a coupling constant of dimension (energy) −1 . Notice that we use natural units with = c = k B = 1. This vertex enables the decay a → γ γ , the Primakoff production in stars-that is, the γ → a scattering in the Coulomb fields of charged particles in the stellar plasma-and the coherent conversion a ↔ γ in laboratory or astrophysical B-fields 9,10 .The helioscope concept, in particular, uses a dipole magnet directed at the Sun to convert axions to...

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“…The maximum magnetic field that can be achieved with this prototype magnet is ≈ 9 T. The magnet is mounted on an azimuthal moving platform that allows to track the Sun for 1.5 h (±8 • in height and ≈ 100 • in azimuth) during sunrise and sunset. To detect the axions, three different types of detectors are attached to the ends of the magnet pipes: a gaseous detector with a novel MICROMEGAS readout (15) and an X-ray telescope with a pn-CCD chip as focal plane detector (16) to detect axions during sunrise, and a Time Projection Chamber (TPC) which covers the opposite end of the magnet pipes, ready to collect axions during sunset (17). CAST has taken data with the conversion region being evacuated during the years 2003 and 2004.…”

Section: Helioscope Implementationsmentioning

confidence: 99%

Axion Searches in the Past, at Present, and in the Near Future

Battesti

Beltrán

Davoudias

et al.

Lecture Notes in Physics

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Summary. Theoretical axion models state that axions are very weakly interacting particles. In order to experimentally detect them, the use of colorful and inspired techniques becomes mandatory. There is a wide variety of experimental approaches that were developed during the last 30 years, most of them make use of the Primakoff effect, by which axions convert into photons in the presence of an electromagnetic field. We review the experimental techniques used to search for axions and will give an outlook on experiments planned for the near future.

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The Micromegas detector of the CAST experiment

Cited by 68 publications

References 17 publications

Gaseous time projection chambers for rare event detection: results from the T-REX project. II. Dark matter

Gaseous time projection chambers for rare event detection: results from the T-REX project. II. Dark matter

New CAST limit on the axion–photon interaction

Axion Searches in the Past, at Present, and in the Near Future

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