Ultra Low-background HPGe Detectors


Ultra low-background HPGe detectors are widely used in underground laboratories for determination of radionuclides activities in environmental or industrial samples at µBq/kg levels and in scientific experiements such as investigation of magnetic moment of neutrino, dark matter search, etc.



  • Task related design (U-type, vertical, down-looking or portable cryostat)
  • Remote not cooled part of preamplifier
  • Zeolite is placed near not cooled part of preamplifier in order to be outside measuring chamber

Cryostat materials

  • Certified materials with low radiation impurities
  • Ultrapure aluminium–silicon alloy with U + Th content < 1, 0.5 or 0.2 ppb for detector holder and endcap
  • Freshly produced electrolytic copper for coldfinger an pedestal
  • Tested on radiopurity selected stainless steel screws and sapphire insulators


  • Transportation of HPGe crystal and cryostat materials by surface freight
  • Minimization of fabrication time (location of materials above ground)
  • Assembly in a cleanroom
  • Cleaning and passivation of copper surfaces
  • Storage of crystal and cryostat materials in a container made from materials effectively slowing down and absorbing neutrons (water and Cd)

Design features

  • Fabrication of large volume HPGe detectors without bulletization
  • Front end electronics made on low-background Teflon substrate
  • Passive screen between front end electronics and HPGe crystal made from Pb with Bi-210 radioactivity < 0.1 Bq/kg
  • Double-crystal HPGe detector design
  • Multi-crystal HPGe detector design