From fbc3a3a903ea29d5488564afc5cfc5c14aa52912 Mon Sep 17 00:00:00 2001 From: Jannik Hofestaedt <jhofestaedt@km3net.de> Date: Thu, 8 Oct 2020 15:24:44 +0200 Subject: [PATCH] Update Detector.md --- pages/Detector.md | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/pages/Detector.md b/pages/Detector.md index c86d6e7..928c39c 100644 --- a/pages/Detector.md +++ b/pages/Detector.md @@ -2,6 +2,7 @@ Title: Detector and Data Taking Author: Jannik **Detector** + The KM3NeT Research Infrastructure will consist of a network of deep-sea neutrino detectors in the Mediterranean Sea with user ports for Earth and Sea sciences. The KM3NeT neutrino detectors employ the same technology and neutrino detection principle, namely a three-dimensional array of photosensors that is used to detect Cherenkov light produced by relativistic particles emerging from neutrino interactions. From the arrival time of the Cherenkov photons (~nanosecond precision) and the position of the sensors (~10cm precision), the energy and direction of the incoming neutrino, as well as other parameters of the neutrino interaction, can be reconstructed. The main difference between different detector designs are the density of photosensors, which is optimised for the study of neutrinos in the few-GeV (ORCA) and TeV-PeV energy range (ARCA), respectively. @@ -15,6 +16,7 @@ The ORCA (Oscillation Research with Cosmics in the Abyss) detector is being inst **Data Acquisition** + The readout of the KM3NeT detector is based on the 'all-data-to-shore' concept, in which all analogue signals from the PMTs that pass a reference threshold are digitised. This data contain the time at which the analogue pulse crosses the threshold level, the time that the pulse remains above the threshold level (known as time-over-threshold, or ToT), and the PMT address. This is typically called a hit. All digital data (25 Gb/s per building block) are sent to a computing farm onshore where they are processed in real time. The recorded data is dominated by optical background noise from Cherenkov light from K40 decays in the seawater, bioluminescence from luminescent organisms in the deep sea. Events of scientific interest are filtered from the background using designated software, which exploit the time-position correlations following from causality. To maintain all available information for the offline analyses, each event contains a snapshot of all the data in the detector during the event. @@ -26,10 +28,12 @@ The acoustic data includes the processed output from the piezo sensors in the DO **Data Taking** + During operation the continuous data stream sent bt the detector is split in runs with typical durations of a few hours. This is done for practical reasons of the data acquisition. In addition, this procedure allows to selected a set of runs with high-quality data based on the monitored detector status, environmental conditions and data quality. The calibration for timing, positioning and photon detection efficiency is done offline using the calibration data. **Simulations** + To assess the detector efficiency and systematics, dedicated Monte Carlo simulations are processed. Due to the changing data-taking conditions of the detector in the deep-sea environment, time-dependent simulation data-sets are required. These are implemented in a run-by-run simulation strategy, where runs are sufficiently small time intervals of data taking with stable conditions. The detector response is simulated individually for these periods. The simulation data are generated at the raw-data level and are subjected to the same filter and reconstruction processing as the real data. Since large statistics are required for precise analyses, the simulation data will significantly exceed the real data in volume. -- GitLab