## 5 Results
### Proton and Alpha Cluster Measurements  
Following the cluster reconstruction and selection process described in the previous section, it is important to examine the key properties of the clusters measured by the Timepix3 Radiation Monitor during the CNA campaign, for all particle types and beam energies with which it was irradiated. As a first step, Figure 9 illustrates the average shape and the 2D ToT profile of clusters originating from protons and alphas with different energies directed orthogonally on the sensor (i.e., beams for which the angle \(\theta\) in Figure 4 is 0\({}^{\circ}\)). The clusters have been aligned according to their reconstructed centre of gravity, and the value of the ToT in each pixel represents the average over millions of individual clusters, excluding all pixels with an averaged ToT value below 1 DAC unit (25 ns), such that spurious reconstructed clusters are not unneceserily emphasized. All clusters are consistently showing larger sizes at higher beam energies, as expected, and the cluster height (i.e., the largest pixel ToT of the cluster) is found in their centre for both protons and alphas at all energies. The latter observation is particularly relevant, because it means that the sensor is not exhibiting the known volcano effect described in the literature for very high energy depositions in Timepix3 detectors [22], where the pixels in the core of the clusters measure a lower ToT as a result of them falling in Regions E and F of the pixel-level calibration curve (see Figure 6). Hence, while at this stage the analysis is only qualitative, the cluster shapes in Figure 9 are already indicating that any saturation effects occurring in the central pixels must not be exceeding (at least on average) Regions C and D of the above curve. After having visualized the cluster shapes, Figure 10 presents the 1D distributions of the total ToT volume of the reconstructed clusters, obtained as the sum of the individual ToT of each pixel in the cluster (as previously shown in Figure 8), for all particle types and energies with which the Timepix3 Radiation Monitor is irradiated orthogonally. All ToT distributions appear as well-resolved peaks, with increasing distribution widths at higher energies, allowing us to fit them with Gaussian functions. The widening of the ToT peaks at high energies can indicate possible resolution effects and non-linearities in the calibration (i.e., saturation), likely in the pixels measuring the highest ToT inside the clusters. In particular, the shape of the ToT peak from 5 MeV protons is showing an extended tail on  
Figure 9: Average shapes of the clusters (averaged over millions of reconstructed clusters) for proton (**top row**) and alpha (**bottom row**) runs at different energies, with orthogonal incidence on the Timepix3 Radiation Monitor. Values below 1 ToT unit averaged over the entire data set are set to 0.  
the low-ToT side, possibly indicating that a fraction of the protons are reaching the end of the sensitive volume and are thereby not depositing their entire energy in the sensor. Meanwhile, the 5.6 MeV alphas display a widening and flattening of the peak, reducing the quality of the Gaussian fit, and suggesting the presence of saturation effects, as further discussed in the next paragraph. Concerning the cluster size, all curves in Figure 10 show well-defined peaks, with the expected size increase for higher energies. Lastly, the distribution of cluster ToT volume of 597 keV protons is plotted again in Figure 11 (left), this time showing all the angles of incidence at which the Timepix3 Radiation Monitor was irradiated, ranging from 0\({}^{\circ}\) to 45\({}^{\circ}\). These cluster ToT distributions are similar, but they can nevertheless be distinguished by fitting them with Gaussian functions, which reveal a slight decrease in the mean cluster ToT for larger angles.