Airborne Gamma-Ray Spectroscopy for Modeling Cosmic Radiation and Effective Dose in the Lower Atmosphere

Abstract

Abstract. In this paper we present the results of a ∼5 hour airborne gamma-ray survey carried out over the Tyrrhenian sea in which the height range (77-3066) m has been investigated. Gamma-ray spectroscopy measurements have been performed by using the AGRS_16L detector, a module of four 4L NaI(Tl) crystals. The experimental setup was mounted on the Radgyro, a prototype aircraft designed for multisensorial acquisitions in the field of proximal remote sensing. By acquiring high-statistics spectra over the sea (i.e. in the absence of signals having geological origin) and by spanning a wide spectrum of altitudes it has been possible to split the measured count rate into a constant aircraft component and a cosmic component exponentially increasing with increasing height. The monitoring of the count rate having pure cosmic origin in the >3 MeV energy region allowed to infer the background count rates in the Tl photopeaks, which need to be subtracted in processing airborne gamma-ray data in order to estimate the potassium, uranium and thorium abundances in the ground. Moreover, a calibration procedure has been carried out by implementing the CARI-6P and EXPACS dosimetry tools, according to which the annual cosmic effective dose to human population has been linearly related to the measured cosmic count rates.

Accuracy of Flight Altitude Measured with Low-Cost GNSS, Radar and Barometer Sensors: Implications for Airborne Radiometric Surveys

“…The aircraft used for the surveys is the Radgyro ( Figure 2 , Figure 3 and Figure 4 ), an experimental autogyro devoted to airborne multiparametric measurements, specifically designed for radiometric surveying [ 14 , 15 ]. The Radgyro is 5.20 m long and 2.8 m high, and has an 83-liter fuel tank placed above the instrumentation to avoid the attenuation of gamma signals coming from the ground due to the interaction with the fuel material.…”

Exploring atmospheric radon with airborne gamma-ray spectroscopy

“…The latter quantity can indeed be obtained also from the parameters of the linear function describing the relation between the count rates in the BEW and the count rates in the CEW, i.e. : where the fit parameters a BEW , b BEW , A CEW and B CEW have been obtained in an independent aircraft plus cosmic background calibration survey (Baldoncini et al, 2017) 2 .…”

“…Gamma-ray measurements are performed with a modular NaI(Tl) scintillation detector arranged in the middle of the Radgyro hull, the AGRS_16L, which is made up of 4 4L crystals having dimensions equal to 10 cm × 10 cm × 40 cm (Guastaldi et al, 2013;Strati et al, 2015). The acquired list mode files, reporting for each ADC channel the energy deposition inside the specific crystal, are processed offline in order to generate for each detector 1Hz energy calibrated gamma spectra, summed up to obtain the gamma-ray spectrum resulting from the whole 16L detection volume (Baldoncini et al, 2017). Radiometric data entering this analysis have been collected at a maximum distance from the coast of about 4.5 km and have been selected by requiring a minimum distance of 300 m, which is meant to exclude gamma-ray signals potentially spoiled by ground radiation.…”

Investigating the potentialities of Monte Carlo simulation for assessing soil water content via proximal gamma-ray spectroscopy

“…As the adopted Monte Carlo simulation method does not structurally provide any background radiation contribution, a cosmic background spectral shape to be subtracted from the experimental measurement is inferred from a 24 hour background calibration measurement according to the approach described in (Baldoncini et al, 2017). Without the introduction of any arbitrary rescaling factor, a good agreement between experimental and simulated spectra is obtained concerning both absolute counting statistics and the spectral shape profile (Figure 9).…”