Noise considerations for a very low threshold semiconductor detector system

Abstract

The search for dark matter motivates develo p ment of a semiconductor detector system with a very low noise threshold. The CoGeNT and MAJORANA p rojects both make use of hy p er-p ure Ge detectors and are in p rinci p le sensitive to the ionization signals p roduced by dark matter p articles scattering from Ge nuclei if sub-keV thresholds can be achieved.We describe p rogress toward mitigating noise on several fronts: the lIf noise that is inherent in ca p acitors and may also be p resent in the de p letion layer of pn junctions, and the aliasing noise that is endemic with FFTs taken digitally over a large frequency range.An o p erating front-end design with an ENC (equivalent noise charge) of 4.5 electrons RMS has been demonstrated.