PDD - Noise Rate and Noise Rate Stability
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6 Experimental Requirements- 6.1 Time Resolution
- 6.2 Waveforms
- 6.3 Dynamic Range and Linearity
- 6.4 Absolute Amplitude Calibration and Stability
- 6.5 Dead time
- 6.6 Sensitivity of optical modules
- 6.7 Noise Rate and Noise Rate Stability
- 6.8 Failure Rate
- 6.9 IceTop
6.7 Noise Rate and Noise Rate Stability
Ice is a very low noise medium; the noise is dominated by radioactivity introduced by the OM itself. The noise rate in individual OMs is required to be less than 0.5 kHz (compared to typically 1 kHz in the present AMANDA array). For that aim, glass spheres with very low radioactivity content (< 0.05% potassium content) should be chosen. Rates for all OMs should be recorded for optimal sensitivity and detector monitoring.
For the muon trigger, this level of noise is readily eliminated by the use of local coincidences (a pair of OMs that are adjacent or separated by no more than one OM report).
Supernova detection is based on the identification of rate excesses over a few seconds. It is made possible by the low noise rates and becomes impossible if the rates are as high as 2 kHz. With 300 Hz noise rates, IceCube could monitor not only our own Galaxy, but also the Magellanic cloud.
Rates have to be recorded every ms with 10 bit dynamic range, with the possibility to adjust artificial dead time between 0 and 1 ms in 10μs steps.
