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Ultra Low-background HPGe detectors0 pages
Ultra Low-background
nnnnHPGe Detectors
nnnnApplication
nnnnUltra low-background HPGe detectors
nnnnare widely used in underground
nnnnlaboratories for determination of
nnnnradionuclides activities in environmental
nnnnor industrial samples at uBq/kg levels and
nnnnin scientific experiements such as
nnnninvestigation of magnetic moment of
nnnnneutrino, dark matter search, etc.
nnnn• Task related design (U-type, vertical, down-looking or portable cryostat)
nnnn• Remote not cooled part of preamplifier
nnnn• Zeolite is placed near not cooled part of preamplifier in order to be outside measuring chamber
nnnnCryostat materials
nnnn• Certified materials with low radiation impurities
nnnn• Ultrapure aluminium - silicon alloy with U + Th content < 1, 0.5 or 0.2 ppb for detector holder and
nnnnendcap
nnnn• Freshly produced electrolytic copper for coldfinger an pedestal
nnnn• Tested on radiopurity selected stainless steel screws and sapphire insulators
nnnnTechnology
nnnn• Transportation of HPGe crystal and cryostat materials by surface freight
nnnn• Minimization of fabrication time (location of materials above ground)
nnnn• Assembly in a cleanroom
nnnn• Cleaning and passivation of copper surfaces
nnnn• Storage of crystal and cryostat materials in a container made from materials effectively slowing
nnnndown and absorbing neutrons (water and Cd)
nnnnDesign features
nnnn• Fabrication of large volume HPGe detectors without bulletization
nnnn• Front end electronics made on low-background Teflon substrate
nnnn• Passive screen between front end electronics and HPGe crystal made from Pb with Bi-210
nnnnradioactivity < 0.1 Bq/kg
nnnn• Double-crystal HPGe detector design
nnnn• Multi-crystal HPGe detector design
nnnnB BALTIC SCIENTIFIC
nnnnINSTRUMENTS
nnnnGamma-rays 43
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