Germanium Detector Array: Difference between revisions

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The [[Germanium|GERmanium]] Detector Array ('''GERDA''') experiment is searching for [[neutrinoless double beta decay]](0vββ) in Ge-76 at the underground [[Laboratori Nazionali del Gran Sasso]] (LNGS). [[Neutrinoless beta decay]] is expected to be a very rare process if it occurs. The collaboration predicts less than one event each year per kilogram of material, appearing as a narrow spike around the 0vββ Q-value(Q_ββ = 2039 keV) in the observed energy spectrum. This means b[[Radiation_protectionRadiation protection|ackground shielding]] is required to detect any rare decays. The LNGS facility has 1400 meters of rock [[overburden]], equivalent to 3000 meters of water shielding, reducing [[Cosmic ray|cosmic radiation]] [[Background radiation|background]].

{{Underlinked|date=December 2014}}

The [[Germanium|GERmanium]] Detector Array ('''GERDA''') experiment is searching for [[neutrinoless double beta decay]](0vββ) in Ge-76 at the underground [[Laboratori Nazionali del Gran Sasso]] (LNGS). [[Neutrinoless beta decay]] is expected to be a very rare process if it occurs. The collaboration predicts less than one event each year per kilogram of material, appearing as a narrow spike around the 0vββ Q-value(Q_ββ = 2039 keV) in the observed energy spectrum. This means b[[Radiation_protection|ackground shielding]] is required to detect any rare decays. The LNGS facility has 1400 meters of rock [[overburden]], equivalent to 3000 meters of water shielding, reducing [[Cosmic ray|cosmic radiation]] [[Background radiation|background]].

== Design ==

The experiment uses high purity enriched [[Germanium|Ge]] crystal [[diodes]] (HPGe) as a beta decay source and [[particle detector]]. The detectors from the HdM and Igex experiments were reprocessed and used in phase 1. The detector array is suspended in a liquid [[argon]] [[cryostat]] lined with copper and surrounded by an ultra-pure water tank. [[Photomultiplier|PMTs]] in the water tank and plastic [[scintillators]] above detect and exclude background [[muons]]. Pulse-shape discrimination (PSD) is applied as a cut to discriminate between particle types.

Phase 2 will increase the active mass to 38kg38 kg using 30 new broad energy germanium (BEGe)  detectors. A magnitude reduction in background is planned to 10^-3−3 counts/(keV·kg·yr) using cleaner materials. This will increase the half-life sensitivity to 10²⁶ years once 100kg100 kg·yr of data is taken and enable evaluation of possible ton-scale expansion.

== Results ==