RTS effect on fake hit rate in Mimostar

RTS effect on fake hit rate in Mimostar 3 Xiangming Sun Lawrence Berkeley National Lab L. Greiner, M. Szelezniak H. Matis T. Stezelberger C. Vu H. Wieman 1

Random telegraph signal (RTS) in Mimostar 3 Random telegraph signal (RTS) found in the Mimostar 3 sensor. The plot shows the continuous ADC sample for a pixel with RTS noise. One can see two jumps in ADC value, which are Random telegraph signals The time length of rising region is similar with the discharge time constant of the charge collecting diode. ~100 ms 2

RTS shape a typical RTS is composed by three types of regions, rising region, plateau and descending region. We call the different of plateau and background as the RTS height. Only the descending region can produce positive CDS(correlated double sampling), which can contribute to the fake hit rate of the sensor. 3

Slope cut noise is treated as the sum of RTS and noise background. a slope cut is used to identify the RTS pixels s_i is the i-th sample if the pixel. The n in the formula is the calculation length of the slope. The slope cut used is 18 with n=150 4

efficiency of the RTS filter using a simulated RTS embedded in the noise The efficiency of finding RTS depends on the RTS height. The efficiency will become lower as RTS height smaller. 5

Fake hit rate plot is a section of the error function The fake hit rate of the sensor decreases as the threshold cut on the CDS signal is raised. If we require a fake hit rate 10^-6, the threshold is about 29 ADC count which is about 133 electron(RMS 6 6. 1 ADC corresponding to 28 electron)

Number of RTS as a function of RTS height • An RTS whose height is less than the CDS threshold can not produce a fake hit. So, we can ignore RT signals with a height that is below the CDS cut of 28 ADC counts. 7

RTS effect on fake hit rate plot is a section of the error function cut in electrons Data set: 45 k sample of 100 k pixel 8

Summary • For un-irradiated Mimostar 3 sensor, the fake hit mainly comes from noise background. the fake hit comes from RTS less than 1 percent 9

RTS pixel map MS 3 RTS pixel map 2. 2% are RTS pixel (based on slope cut) 10

Peaks from narrow low current periods Fast rising time and normal descending time rising time is about 10 ms The rapid rise region gives a negative CDS so it does not contribute fake hits, but there are probably an equal number with the opposite sign (see next slide) and we have to check that these have been properly counted. 11

Forward biased diode signal low I high Vdiode low I Vdiode high 12