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| applications:space:grid:grid02:start [17:45 10/06/2022] – [References] jhulsman | applications:space:grid:grid02:start [18:29 10/06/2022] (current) – [Results] jhulsman |
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| === Breakdown Voltage === | === Breakdown Voltage === |
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| {{ :applications:space:grid:grid02:grid02_vbd_time.png?nolink&300|}} | {{ :applications:space:grid:grid02:grid02_vbd_time.png?nolink&310|}} |
| The temperature dependance of the breakdown voltage (V$_{bd}$) is fitted with a linear function. It's gradient (or temperature coefficient) $k_b$ is found to be 21.5mV/K. As the figure to the right shows, after applying the temperature correction, no significant features are observed. V$_{bd}$ therefore is minimally affected by radiation damage (more time in space = more radiation damage). | The temperature dependance of the breakdown voltage (V$_{bd}$) is fitted with a linear function. It's gradient (or temperature coefficient) $k_b$ is found to be 21.5mV/K. As the figure to the right shows, after applying the temperature correction, no significant features are observed. V$_{bd}$ therefore is minimally affected by radiation damage (more time in space = more radiation damage). |
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| === Dark Current === | === Dark Current === |
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| {{ :applications:space:grid:grid02:grid02_dc_time.png?nolink&300|}} | {{ :applications:space:grid:grid02:grid02_dc_time.png?nolink&310|}} |
| The SiPM dark current is expressed through $I_{dark}=DCR*C_{pix}*(V_{bias} − V_{bd}) · ECF$ (see [[https://arxiv.org/pdf/2205.10506.pdf|paper]] for more information), where the DCR is expressed by the Field-Enhanced Shockley-Read-Hall (FE-SRH) model. For a constant bias voltage, the effective electric field strength is thought to remain unchanged. However, when fitting the dark current with this model while keeping the electric field strength as a free parameter, it was found that this is not the case when exposed to increasing radiation damage. This is shown in the figure (to the right) where the dark current increases by $\approx 93/96/98/110 \frac{\mu A}{year}$. | The SiPM dark current is expressed through $I_{dark}=DCR*C_{pix}*(V_{bias} − V_{bd}) · ECF$ (see [[https://arxiv.org/pdf/2205.10506.pdf|paper]] for more information), where the DCR is expressed by the Field-Enhanced Shockley-Read-Hall (FE-SRH) model. For a constant bias voltage, the effective electric field strength is thought to remain constant. The dark current is therefore fitted with respect to temperature (on a daily basis) to the aforementioned model where the electric field strength is a free parameter. After the fit, the expected dark current at a reference temperature of $5^{^\circ}C$ is shown with respect to time. This is shown in the figure (to the right) where the dark current increases by $\approx 93/96/98/110 \frac{\mu A}{year}$. |
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| === Dark Count Noise === | === Dark Count Noise === |
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| | Charge injections are used to look into the energy resolutions and noise contributions within the detector. Results in ADC channels are subsequently converted to equivalent energy with a scale factor ~0.027 keV/channel. When the bias voltage is switched off the width of the charge injection peak is heavily dominated by the electronics noise (irrespective of radiation damage). However, when the bias voltage is switched on the dark count noise becomes significant. |
| | Through Campbell’s theorem, the total noise can be correlated and fitted with respect to the dark current. This is shown in the figure below. The results show a noise increase of ~7.5 keV/year for each channel. |
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| | {{ :applications:space:grid:grid02:grid02_noise_idark.png?direct&600 |}} |