A Micromegas-based low-background x-ray detector coupled to a slumped-glass telescope for axion research

Aznar, Francisco; Castel, J.; Christensen, Finn Erland; Dafní, T.; Decker, Todd A.; Ferrer‐Ribas, E.; Garcı́a, Juan Antonio; Giomataris, I.; Garza, J.G.; Hailey, Charles J.; Hill, R.M.; Iguaz, F.J.; Irastorza, I.G.; Jakobsen, Anders Clemen; Luzón, G.; Mirallas, H.; Papaevangelou, T.; Pivovaroff, M. J.; Ruz, J.; Vafeiadis, T.; Vogel, Julia K.

doi:10.1088/1475-7516/2015/12/008

Cited by 32 publications

(41 citation statements)

References 67 publications

(102 reference statements)

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“…The spot position has been measured with both a dedicated in-situ laser alignment, as well as periodically monitored with an x-ray generator from the other side of the magnet. A detailed description of the commissioning, alignment and spot-calibrations can be found in reference [37].…”

Section: Low Background X-ray Detection With Micromegasmentioning

confidence: 99%

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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Section: Low Background X-ray Detection With Micromegasmentioning

confidence: 99%

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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“…The objective of the T-REX project [26, 27] has been to study the applicability of Micromegas readouts TPCs to rare event searches (not just to WIMP searches, but also axions [28] and double beta decay [29]). The T-REX activity1 during the last years has included the study and characterization of novel Micromegas readouts [30], especially those of microbulk type [31], study and improvement of their radiopurity [32], simulation and development of discrimination algorithms [33], and the construction and test of prototypes [28, 34–37]. It is our claim here that gaseous detectors are very promising options for low-mass WIMP detection for many reasons.…”

Section: Introductionmentioning

confidence: 99%

TREX-DM: a low-background Micromegas-based TPC for low-mass WIMP detection

et al. 2016

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If Dark Matter is made of Weakly Interacting Massive Particles (WIMPs) with masses below GeV, the corresponding nuclear recoils in mainstream WIMP experiments are of energies too close, or below, the experimental threshold. Gas Time Projection Chambers (TPCs) can be operated with a variety of target elements, offer good tracking capabilities and, on account of the amplification in gas, very low thresholds are achievable. Recent advances in electronics and in novel radiopure TPC readouts, especially micro-mesh gas structure (Micromegas), are improving the scalability and low-background prospects of gaseous TPCs. Here we present TREX-DM, a prototype to test the concept of a Micromegas-based TPC to search for low-mass WIMPs. The detector is designed to host an active mass of kg of Ar at 10 bar, or alternatively kg of Ne at 10 bar, with an energy threshold below 0.4 keVee, and is fully built with radiopure materials. We will describe the detector in detail, the results from the commissioning phase on surface, as well as a preliminary background model. The anticipated sensitivity of this technique may go beyond current experimental limits for WIMPs of masses of 2–8 GeV.

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“…The Micromegas readouts were built with the microbulk technique 31 , out of copper and kapton, and were patterned with 500 µm pixels interconnected in the x and y directions 32 . These design choices are the outcome of a longstanding effort to understand and reduce background sources in these detectors 33,34 . This effort has led to the best background levels (∼10 −6 keV −1 cm −2 s −1 ) ever obtained in CAST.…”

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confidence: 99%

“…its focal point 34 . This experience is particularly valuable to develop a next-generation scaled-up helioscope.…”

mentioning

confidence: 99%

New CAST limit on the axion–photon interaction

2017

Nature Phys

879

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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A Micromegas-based low-background x-ray detector coupled to a slumped-glass telescope for axion research

Cited by 32 publications

References 67 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

TREX-DM: a low-background Micromegas-based TPC for low-mass WIMP detection

New CAST limit on the axion–photon interaction

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