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Low background facilities at LSM. Pia Loaiza. ILIAS meeting, Modane January 12 th 2005. Ge detectors at LSM. As S ~ /BDF, Gentiane and IRIS have roughly the same sensitivity at 583 keV and 1461 keV. At present, the sensitivity are, typically, 1 mBq/kg for “reasonables”
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Low background facilities at LSM Pia Loaiza ILIAS meeting, Modane January 12th 2005
Ge detectors at LSM As S ~ /BDF, Gentiane and IRIS have roughly the same sensitivity at 583 keV and 1461 keV. At present, the sensitivity are, typically, 1 mBq/kg for “reasonables” mass and measurement time.
On-going projects at the LSM • Improvement of a low background Ge detector (IRIS, 400 cc). • Prospective construction materials are being measured. Monte Carlo simulations are performed to get the distinct contribution to the background from the assembly • materials and to determine the maximum acceptable radioactivities in order to get an improvement of a factor 5 in the detector background. • We’ve found a high Th activity (0.13 Bq/kg @ 238 keV) in one of the insulators near the crystal, which need to be replaced by other material.
On-going projects at the LSM • New planar Ge detector : our needs regarding low-energy gamma detection • require a new planar Ge (diam = 80 mm, d=35 mm), with a resolution of • 0.7 keV at 50-60 keV. Performances of detectors in the market are being • evaluated. • Cryogenerators : We plan to equip one Ge detector with a system • of cryogenerators. Evaluation of possibilities of installation on one • of our detectors is under way. • Constructionof a Radon precision • measuring facility, with a sensitivity of • ~ mBq/m3 (Vol. 70 l)
Radon trapping facility Installation September 2004
Radon trapping facility Time during which radon is trapped in the « filter » : Tr = K(T) M / Q K(T) : dynamic adsorption coeff. M : charcoal mass Q : Air rate 2 charcoal towers : T1 = -53 C, T2 = -45 C M = 2 x 450 kg Radon purification by adsorption in charcoal Vol. clean air : 150 m3/h Activity 222Rn = 15 mBq/m3