The NEXT experiment

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• 作者：J.J. Gomez-Cadenas ^{gomez@mail.cern.ch" class="auth_mail" title="E-mail the corresponding author} ; on behalf of the NEXT collaboration
• 关键词：Majorana neutrinos ; High Pressure Xenon chamber (HPXe) ; Double beta decay ; NEXT ; Electroluminescence
• 刊名：Nuclear and Particle Physics Proceedings
• 出版年：2016
• 出版时间：April-June 2016
• 年：2016
• 卷：273-275
• 期：Complete
• 页码：1732-1739
• 全文大小：1633 K

文摘

NEXT (Neutrino Experiment with a Xenon TPC) is an experiment to search neutrinoless double beta decay processes (ββ0ν$\beta \beta 0\nu$). The isotope chosen by NEXT is ¹³⁶Xe. The NEXT technology is based in the use of time projection chambers operating at a typical pressure of 15 bar and using electroluminescence to amplify the signal (HPXe). The main advantages of the experimental technique are: a) excellent energy resolution; b) the ability to reconstruct the trajectory of the two electrons emitted in the decays, a unique feature of the HPXe which further contributes to the suppression of backgrounds; c) scalability to large masses; and d) the possibility to reduce the background to negligible levels thanks to the barium tagging technology (BaTa).

The NEXT roadmap was designed in four stages: i) Demonstration of the HPXe technology with prototypes deploying a mass of natural xenon in the range of 1 kg; ii) Characterisation of the backgrounds to the ββ0ν$\beta \beta 0\nu$ signal and measurement of the ββ2ν$\beta \beta 2\nu$ signal with the NEW detector, deploying 10 kg of enriched xenon and operating at the LSC; iii) Search for ββ0ν$\beta \beta 0\nu$ decays with the NEXT-100 detector, which deploys 100 kg of enriched xenon; iv) Search for ββ0ν$\beta \beta 0\nu$ decays with the BEXT detector, which will deploy masses in the range of the ton and will introduce two additional handles, only possible in a HPXe: a) A magnetic field, capable of further enhancing the topological signal of NEXT; and b) barium-tagging (a technique pioneered by the EXO experiment which is also accessible to NEXT).

The first stage of NEXT has been successfully completed during the period 2009–2013. The prototypes NEXT-DEMO (IFIC) and NEXT-DBDM (Berkeley) were built and operated for more than two years. These apparatuses have demonstrated the main features of the technology. The experiment is currently developing its second phase. The NEW detector is being constructed during 2014 and will operate in the LSC during 2015. The NEXT-100 detector will be built and commissioned during 2016 and 2017 and will start data taking in 2018. NEXT-100 could discover ββ0ν$\beta \beta 0\nu$ processes if the period of the decay is equal or less than 6&times;10²⁵$6\&<font\; color="red">time</font>s;{10}^{25}$ year. The fourth phase of the experiment (BEXT) could start in 2020.