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The MAJORANA project (styled ) is an international effort to search for neutrinoless double-beta (0νββ) decay in 76Ge. The project builds upon the work of previous experiments, notably those performed by the Heidelberg–Moscow〔 〕 and IGEX〔 〕 collaborations, which used high-purity germanium (HPGe) detectors, to study neutrinoless double-beta decay. The first stage of the project is the Majorana Demonstrator, designed to demonstrate the technique and evaluate a ton-scale experiment. Cryostats housing up to 40 kg of natural and enriched germanium detectors are being deployed in low-background vacuum cryostats, underground at the Sanford Underground Laboratory in Lead, South Dakota. Following the Demonstrator, the collaboration intends to merge with the GERDA collaboration to build a much larger experiment. ==Physics== The goal of the project is to search for 0νββ decay in 76Ge using HPGe detectors. Observation of 0νββ would establish that the neutrino is a Majorana particle and demonstrate violation of lepton number conservation, validating the seesaw mechanism as the explanation for the neutrino mass scale. It would also place constraints on the absolute neutrino mass. The principal goal of the Majorana Demonstrator is to demonstrate the feasibility of achieving the background required in a ton-scale experiment. This corresponds to 4 counts/tonne/yr in a 4 keV window around the 0νββ Q value of 2039 keV, which scales to 1 count/ton/yr in a ton scale experiment. The experiment will use a mixture of detectors made with natural germanium and enriched germanium, allowing it to confirm or refute the controversial claim for 0νββ observation in 76Ge by Klapdor-Kleingrothaus et al. If low enough electronic noise is achieved the Demonstrator may also make a search for WIMPs and axions. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「MAJORANA」の詳細全文を読む スポンサード リンク
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