Underground Crystal Growth Natural division TeO 2 growth Ge growth A. Giuliani / J. Morales  For Ge, cosmogenics is very critical  For Te, role of cosmogenics in the background is under test see Susana’s presentation

Crucible effects in TeO 2 crystals (1) A contamination in 190 Pt is appreciable in many TeO 2 crystals the corresponding alpha peak at 3.3 MeV is visible in the spectrum Given the low I.A. of 190 Pt (0.014%) the amount of natural Pt must be huge up to 1-2 mg of natural Pt in some crystals The Pt contamination is dangerous for two reasons:  degraded alpha can populate the DBD spectral region  bolometer performance seems to be affected Possible origin of Pt: the crucible used for the crystal growth (Bridgman method)

Crucible effects in TeO 2 crystals (2) Initially, efforts will be put to solve Pt problem:  quantify exactly Pt amount  study problem with expert of SICCAS (growth company)  study modification of crystal growth procedure  study alternative materials for crucible (Iridium?)

middle term deadline October meeting 3 months 6 months 1 year preliminary study on Pt contamination effect Activities and temporal plans

Working group (preliminary) A. Giuliani– Como / INFN- leader J. Morales– Zaragoza– co-leader E. Previtali– Milano / INFN J.A. Villar – Zaragoza E. Norman – Berkeley (to be confirmed) F. Avignone – South Carolina (to be confirmed) C. Bucci - LNGS / INFN M. Pedretti- Como / INFN

Costs in the first year Contacts with Canberra for Ge plant 5000 € Contacts with SICCAS for discussion on crucible effects 5000 € R&D for new crucible materials and/or modification of growth procedure15000 € Travel and meetings of Working Group € TOTAL35000 €