Publications associated with Dark matter

Effect of recrystallisation on the radioactive contamination of CaWO<inf>4</inf>crystal scintillators

Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment 631 (2011) 44-53

FA Danevich, IK Bailiff, VV Kobychev, H Kraus, M Laubenstein, P Loaiza, VB Mikhailik, SS Nagorny, AS Nikolaiko, S Nisi, IM Solsky, G Warot

Minimising intrinsic radioactivity of crystal scintillators is of particular importance for experiments searching for rare events. We studied the impact of the crystal production process (recrystallisation) on the level of radioactive contamination of CaWO4crystal scintillators. Several samples of single crystal scintillators were produced using the recrystallisation procedure. It is shown that this has a significant effect on the radioactive contamination of the crystals. Depending on the stage of recrystallisation the activity due to210Po (product of210Pb decay) varies in the range 0.031.32 Bq kg-1while the activity of238U varies from 0.04 to 0.33 Bq kg-1. We found that uranium is rejected by the crystal with a segregation coefficient ≈0.3. The improvement in radiopurity of CaWO4by one order of magnitude due to recrystallisation has been demonstrated. The additional benefit of this process is the improvement in the energy resolution. A programme to develop radiopure CaWO4crystal scintillators is discussed briefly. © 2010 Elsevier B.V. All rights reserved.

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