[Triumf-seminars] TRIUMF Seminar today at 14:00

[postmaster@admin.triumf.ca]

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Date/Time: Wed 2004-05-26 at 14:00

Location:  Auditorium          

Speaker:   Richard Lange (SNO (BNL))

Title:     Rn and other Radio-chemical Backgrounds in the SNO Detector

Abstract: SNO, a 1000 tonne heavy water Cerenkov detector located in Sudbury Canada is now being prepared for the start of its third phase of operation. This phase includes measuring the solar 8B neutral current (NC) flux via a set of high radio-purity 3He gas proportional counters dubbed Neutral Current Detectors (NCDs) that have been immersed in the detector. Of great concern are radioactivities in the detector that can produce gamma-rays of energies in excess of 2.2 MeV. These high energy gamma-rays can photodisintegrate Deuterium (Q = -2.2 MeV) and thus mimic the NC channel. Of the two most likely offenders, 214Bi of the U-chain is the major culprit; 208Tl of the Th-chain being the other. Because 214Bi is supported by the insidious noble gas 222Rn (3.235 d), one must limit the ingress of Rn into the detector from the underground air. Rn is present in the underground SNO lab at the level of ~3pCi/L (100Bq/m^3). This talk will center on the method used to monitor the levels of Rn in the air and waters of SNO and the efforts employed to remediate Rn ingress into the detector. Other sources of neutrons will also be discussed briefly.

Stimulants available 15 minutes before the talk.

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