Low Background Micromegas in CAST

7th International Symposium on Large TPCs for Low-Energy Rare Event Detection

Garza, J.G.^1 ; Aune, S.^2 ; Aznar, F.^1,6 ; Calvet, D.^2 ; Castel, J.F.^1 ; Christensen, F.E.^4 ; Dafni, T.^1 ; Davenport, M.^5 ; Decker, T.^3 ; Ferrer-Ribas, E.^2 ; Galán, J.^2 ; García, J.A.^1 ; Giomataris, I.^2 ; Hill, R.M.^3 ; Iguaz, F.J.^1 ; Irastorza, I.G.^1 ; Jakobsen, A.C.^4 ; Jourde, D.^2 ; Mirallas, H.^1 ; Ortega, I.^1,5 ; Papaevangelou, T.^2 ; Pivovaroff, M.J.^3 ; Ruz, J.^3 ; Tomás, A.^1,7 ; Vafeiadis, T.^5 ; Vogel, J.K.^3

Grupo de Física Nuclear y Astropartículas, University of Zaragoza, Zaragoza, Spain^1

Irfu, CEA, Centre de Saclay, Gif sur Yvette, France^2

Lawrence Livermore National Laboratory, Livermore

CA, United States^3

Technical University of Denmark, DTU Space, Kgs. Lyngby, Denmark^4

CERN, European Organization for Particle Physics and Nuclear Research, Geneva, Switzerland^5

Centro Universitario de la Defensa, Universidad de Zaragoza, Ctra. de Huesca s/n, Zaragoza

50090, Spain^6

High Energy Physics Group, Brackett Laboratory, Imperial College, London, United Kingdom^7

关键词: CERN axion solar telescopes;    Discrimination algorithms;    Energy thresholds;    High granularity;    Latest development;    Micromegas detector;    Strong magnetic fields;    Underground laboratory;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/650/1/012008/pdf
DOI  :  10.1088/1742-6596/650/1/012008

来源: IOP

【 摘 要 】

Solar axions could be converted into x-rays inside the strong magnetic field of an axion helioscope, triggering the detection of this elusive particle. Low background x-ray detectors are an essential component for the sensitivity of these searches. We report on the latest developments of the Micromegas detectors for the CERN Axion Solar Telescope (CAST), including technological pathfinder activities for the future International Axion Observatory (IAXO). The use of low background techniques and the application of discrimination algorithms based on the high granularity of the readout have led to background levels below 10-6counts/keV/cm2/s, more than a factor 100 lower than the first generation of Micromegas detectors. The best levels achieved at the Canfranc Underground Laboratory (LSC) are as low as 10-7counts/keV/cm2/s, showing good prospects for the application of this technology in IAXO. The current background model, based on underground and surface measurements, is presented, as well as the strategies to further reduce the background level. Finally, we will describe the R&D paths to achieve sub-keV energy thresholds, which could broaden the physics case of axion helioscopes.