# State-of-the-Art Mobile Radiation Detection Systems for Different Scenarios
## 4 Mobile Radiation Detection Systems
### Radiation Detection and Gamma Spectrometry
#### 4.2.2 Airborne Survey
[PERSON] et al. [67] presented a fixed-wing UAV solution for mapping large contaminated areas, like nuclear power plant post-disasters (Figure 9a). The take-off weight is 8.5 kg (1 kg payload) and features an autonomy greater than 1 h. The payload consisted in two SIGMA-50 CsI(Tl) scintillation detectors. Due to the survey speed of 14-18 m/s and low altitude measurements (40-60 m), it was possible to achieve dose rate maps with a high spatial resolution (20 m pixel\({}^{-1}\)). A laser-range finder on board was used to measure the height above ground; however, the tall vegetation canopies prevented the laser beam to reach the ground (wrong height results). Therefore, a digital elevation model was used to directly correct all measurements to obtain dose-rate at 1 m AGL. Some technical features of the platform system are: the possibility to hand-launch and recover the platform by parachute, flight autonomy greater than 1 h that allows launching the platform from a safe place, accomplishing the mission, and returning back, and navigation autonomy (fly according to pre-planned waypoints). Some of the drawbacks reported were: the saturation of the detectors due to the high doses encountered nearby the \"Red forest\", as well as the weather influence in UAV flights (rain and wind)--sometimes the local wind variation led to ground speeds of 25 m/s (tailwind), despite target speed selection of 14-18 m/s. From the survey experience, the time response of the detection system will be improved to accomplish higher gamma fluxes, by replacing one SIGMA-50 by one CZT detector (GR1, Kromek). The use of CeBr\({}_{3}\) and LaBr\({}_{3}\) scintillators is also anticipated in the near future--due to their excellent energy resolution and optical yields, even for small sensor volumes. The development of radiation sensors in unmanned fixed-wings aircraft was also explored by [PERSON] and [PERSON] [170]. Two UAV were equipped with irradiation detectors:  
* Mid-sized Ranger aircraft (Figure 9b)--with an autonomy of 5 h and flight speeds from 100-220 km/h, a maximum take-off weight (MTOW) of 270 kg, and a payload capacity of 40 kg. In this platform, a GM counter for external dose rate monitoring was installed, a 15.24 \(\times\) 10.16 (cm) NaI(Tl) scintillation detector used for radioactive plume localization, and a 5 \(\times\) 5 \(\times\) 5 mm\({}^{3}\) CZT detector housed inside the sampling unit (this detector also accounts for the possible saturation of the large NaI scintillator). * Patria MASS mini-UAV (Figure 9c)--with an autonomy of 1 h at cruise speed of 60 km/h and an MTOW of 3 kg, it can transport payloads up to 0.5 kg. A cylindrical CsI detector with 38 mm (diameter) \(\times\) 13 mm (length) crystal was used in the fuselage, which revealed a poor energy resolution (12% at 662 keV), and a radioactive particle air sampler was mounted above the aircraft. UAVs can operate in both manual and automatic fly modes, and the measurement data can be sent in real time to the ground station. [PERSON] et al. [43] used the GEANT4 simulation tool to analyze the characteristics of CsI(Na), CsI(Tl), LaBr\({}_{3}\), and cerium-doped lutetium-yttrium oxyorthosilicate LYSO(Ce) scintillation crystals for use in airborne environmental radiation monitoring, particularly UAVs. They concluded that LaBr\({}_{3}\) is the best candidate due to its detection efficiency and energy resolution. However, due to the self-activity of this crystal and the corresponding increase in the STN ratio at low energies, an alternative, such as the CeBr\({}_{3}\) crystal, must be analyzed in the future, as well as a better way to shield these crystals against atmospheric exposure (hygroscopic behavior). The fast search for radioactive sources in security (e.g., lost or stolen source) and safety scenarios (e.g., nuclear disaster mitigation) can be achieved using UAV. Despite the fact tahr a fixed-wing UAV can be used for fast surveys, these platforms normally require higher source activities (to be detected) and need a runway.