Sub-electron noise measurements on repetitive non-destructive readout devices

We demonstrate the use of a silicon detector based on a DEPFET device, with sub-electron readout noise ( 0.6 e - ENC). The so-called repetitive non-destructive readout (RNDR) detector was realised by putting two single DEPFETs next to each other, and connecting their charge storing region by an additional gate. By every transfer from gate 1 to 2 and vice versa the signal charge can be measured non-destructively. By taking the average value of a large number ( n ) of these measurements the serial noise is reduced by 1 / n . This way of readout does not only reduce the white noise, but also averages out the 1 / f noise. Because the whole readout time is n times longer than the time for one readout, the device is interesting for low-noise and low-flux applications. in advantage of such a detector is the ability to reduce the influence of 1 / f noise to the readout noise. The theoretically and experimentally achievable resolution for different operating parameters (leakage current, readout noise, number and duration of readouts) were investigated by Monte-Carlo simulations and measured on single pixel RNDR devices.