Figure 3: 2D hitmap of events detected in the sunrise detector in a typical in situ calibration run (left), as well as in the background (middle) and tracking (right) data (both K and L data sets of Table 1). | Nature Physics

Figure 3: 2D hitmap of events detected in the sunrise detector in a typical in situ calibration run (left), as well as in the background (middle) and tracking (right) data (both K and L data sets of Table 1).

From: New CAST limit on the axion–photon interaction

Figure 3

The calibration is performed with an X-ray source placed ∼12 m away (at the sunset side of the magnet). The contours in the calibration run represent the 95%, 85% and 68% signal-encircling regions from ray-trace simulations, taking into account the source size and distance. In the tracking and background plots, grey full circles represent events that pass all detector cuts but that are in coincidence with the muon vetoes, and therefore rejected. Black open circles represent final counts. Closed contours indicate the 99%, 95%, 85% and 68% signal-encircling regions out of detailed ray-trace simulations of the XRT plus spatial resolution of the detector. The large circle represents the region of detector exposed to daily energy calibration.

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