# A Two-Dimensional Non-Destructive Beam Monitoring Detector for Ion Beams
## 4 Conclusions and Outlook  
The \(\pi^{2}\) detector is a user-friendly, cost-effective solution for monitoring the profile of ion beams with minimum disturbance and precision better than 0.1 mm. It is easy to install and remove, and can be adapted to any beam line. Dedicated software allows for the real-time visualisation of the beam footprint on the scintillator screen and extraction of beam parameters such as FWHM in both the horizontal and vertical axis. The detector is currently used regularly to monitor an 18 MeV proton beam for research activities at the Bern medical cyclotron laboratory. The instrument's performance was evaluated in several tests carried out using the beam transfer line available in the facility. In the first experiment, we performed beam intensity scans from \(2\cdot 10^{10}\) cm\({}^{-2}\cdot\) s\({}^{-1}\) to \(5\cdot 10^{11}\) cm\({}^{-2}\cdot\) s\({}^{-1}\), and observed a linear response of the scintillator in the whole range. From this test, a calibration curve to scale the \(\pi^{2}\) image to proton flux units was obtained. A second experiment showed that the beam profile measurements given by the \(\pi^{2}\) are consistent with the ones obtained using both radiochromic films and the UniBeAM detector. In a third experiment, the amount of beam scattering introduced by the scintillating foil was assessed. The effect on the transversal beam profile downstream the \(\pi^{2}\) is the convolution with a Gaussian distribution with standard deviation equal to 47 \(\upmu\)m per cm of drift space. Finally, an irradiation study up to a total integrated proton flux of \(3\cdot 10^{15}\) cm\({}^{-2}\), in which the flux measured by the \(\pi^{2}\) was continuously compared with the measurement given by a Faraday  
Figure 12: \(\pi^{2}\) response as a function of the integrated proton flux. The top plot compares the flux calculated from the Faraday Cup’s current measurement to that obtained from the calibrated \(\pi^{2}\) image, as a function of the integrated proton flux. The bottom plot shows the ratio between both measurements (black markers), and a 10-sample moving average (blue line) to guide the eye.  
Cup installed downstream the detector ruled out any radiation-induced degradation of the \(\pi^{2}\) response.  
The results presented in this paper show that the \(\pi^{2}\) detector has potential to be industrialised, since it can be used to monitor accelerated ion beams in a wide range of applications encompassing medical radioisotope production, proton therapy and radiation hardness studies.  
[PERSON] conceived the \(\pi^{2}\) detector; [PERSON], [PERSON], [PERSON] and [PERSON] contributed to the construction of the detector; [PERSON], [PERSON], [PERSON] and [PERSON] performed the beam tests and analysed the data; [PERSON], [PERSON], [PERSON] and [PERSON] wrote the paper; [PERSON], [PERSON], [PERSON], [PERSON], [PERSON], [PERSON], [PERSON] and [PERSON] revised the paper; [PERSON] coordinated the project. All authors have read and agreed to the published version of the manuscript.  
This research was partially funded by the Swiss National Science Foundation (SNSF). Grants: 200021_175749, CRSII5_180352, CR23I2_156852.  
Not applicable.  
We acknowledge contributions from the LHEP engineering and technical staff who helped us with the mechanical and electronics challenges during the prototype development and installation. We thank the SWAN team for the support in the operation of the cyclotron, [PERSON] from the TERA Foundation at CERN as well as our colleagues and students [PERSON], [PERSON], [PERSON], [PERSON], [PERSON], [PERSON] and [PERSON].  
The authors declare no conflict of interest.