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SUMMARY:Purification of large volume of liquid argon for the LEGEND-200 ex
 periment
DTSTART;VALUE=DATE-TIME:20210917T171500Z
DTEND;VALUE=DATE-TIME:20210917T173000Z
DTSTAMP;VALUE=DATE-TIME:20260510T052803Z
UID:indico-contribution-74@indico.physics.ucsd.edu
DESCRIPTION:Speakers: Grzegorz Zuzel (Jagiellonian University)\nThe LEGEND
 -200 experiment is under construction at the Laboratori Nazionali del Gran
  Sasso (LNGS) in Italy. Its main goal is a background-free search for neut
 rinoless double beta decay of Ge-76. Up to 200 kg of bare high purity germ
 anium (HPGe) detectors with enrichment in Ge-76 beyond 86% will be deploye
 d in liquid argon (LAr). The LAr will serve as cooling medium for the dete
 ctors as well as a passive and an active shield. For the latter the LAr in
 strumentation will be composed of light guiding fibers connected to silico
 n photomultipliers detecting scintillation light of argon. It has been alr
 eady shown in the GERDA experiment that the LAr veto was a very powerful t
 ool for background rejection and minimization. Details of the LAr veto sys
 tem will be presented in a dedicated talk. \n   The scintillation properti
 es of LAr (attenuation length\, triplet life time) are worsened by presenc
 e (at a sub-ppm level) of electronegative impurities such as oxygen\, wate
 r and nitrogen due to quenching and absorption processes. As a consequence
 \, the efficiency of the LAr veto may be significantly influenced. In orde
 r to achieve best possible performance of the veto\, LAr will be purified 
 during initial filling of the LEGEND-200 cryostat. \n   The design\, const
 ruction and performance of a system capable to purify 65 m3 (91 tons) of l
 iquid argon to sub-ppm level will be presented. The quality of the process
 ed liquid is monitored in real time by measuring the triplet life time and
  simultaneous direct measurement of concentrations of impurities like wate
 r\, oxygen and nitrogen down to 0.1 ppm. Scintillation properties of LAr f
 illed into the cryostat are also be determined in real time by a dedicated
  apparatus (LLAMA). For the LAr filled into the cryostat the measured trip
 let life time is in the range of 1.3 mico_s. If needed\, the LAr purificat
 ion system may be also used later to purify LAr filled in the cryostat in 
 the loop mode. A dedicated cryogenic pump has been installed on its bottom
 . The pump is capable to circulate the LAr between the purification system
  and the cryostat.\n\nhttps://indico.physics.ucsd.edu/event/1/contribution
 s/74/
LOCATION:
URL:https://indico.physics.ucsd.edu/event/1/contributions/74/
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