Development of a novel high-sensivitiy LAr purity monitor based on an $α$-source

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dc.creatorBadertscher, A.
dc.creatorLaffranchi, M.
dc.creatorRubbia, A.
dc.date2004-12-26
dc.date.accessioned2026-07-07T05:53:49Z
dc.date.available2026-07-07T05:53:49Z
dc.descriptionA novel liquid argon (LAr) purity monitor was developed with a sensitivity to electronegative impurities of the order of ppb (O$_2$ equivalent). Such a high purity is e.g. needed in a LAr drift chamber. The principle is to measure the lifetime of quasifree electrons in LAr, since this is the important parameter for the operation of a drift chamber. Free electrons are produced by ionizing the LAr with $α$-particles emitted by the $^{210}Po$ chain daughter of an isotope $^{210}Pb$ source. From a measurement of the charge of the electron cloud at the beginning and at the end of a drift path, together with the drift time, the lifetime of the electrons is obtained. The $α$-particles have a very short range of about 50 μ$m in LAr and the ionization density is very high, typically between $750÷1500\rm MeV/cm$, leading to a high recombination rate. To suppress the recombination of the argon ions with the electrons, the $α$-source was put in a strong electric field of $40÷150$ kV/cm. This was achieved by depositing the source on the surface of a spherical high voltage cathode with a diameter of about 0.5 mm. The anode was also made as a sphere of about the same diameter as the cathode, thus, close to the axis between the two electrodes the electric drift field was approximately a dipole field.
dc.description15 pages, 9 figures
dc.identifierhttps://arxiv.org/abs/physics/0412166
dc.identifierhttp://arxiv.org/abs/physics/0412166
dc.identifier.urihttp://salesiana.dossiersoluciones.com/handle/123456789/86771
dc.subjectInstrumentation and Detectors
dc.titleDevelopment of a novel high-sensivitiy LAr purity monitor based on an $α$-source
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