The radiation protection group uses standardised proportional chambers for site surveillance. State-of-the-art technology uses current-to-frequency converters for reading out these chambers. The technological challenge is long term stability, autocalibration and very long periods with background radiation only, i.e. extremely low level signals in the femtoAmpere range. Early in 2012 the radiation protection group launched a microelectronics project for developing an ASIC that could serve as the frontend of an efficient, autocalibrating measurements chain. Measuring 100fA being a challenge already the system needs to work under the local climatic conditions if the original aim, namely to include environmental background measurements, is to be kept. Middle of 2014 we have the first version of the ASIC working smoothly, helping us to understand noise and drift phenomena and paving the way for a second run at the chip foundry.
Current-to-frequency converter "Utopia"