Our project is focused on both development of a radio indirect techniques for detecting cosmic neutrinos (with a km3 neutrino detector in a salt mine) to searching the High Energy Universe, and theoretical and experimental work to characterize radio wave propagation and antennas behaviour in a multi-layered medium, where each layer has a width of a few centimeters and different constituent impurities. As stated in the Description of the action (DoA) we had specific objectives in two directions: A. Propagation in unconventional media, and B. Cosmic neutrinos detection in salt domes. Table 3 in DoA specified as publications the following deliverables: (a) 2 articles submitted to conferences (month 14, 20), (b) 3 articles submitted to journals (months 17, 20 and 24). All this has been accomplished (details are given in the following).
Regarding direction A, as waves propagate in a non-ideal medium before being measured by radio antennas, it is impetuous to have first a good geophysical material description for radio wave propagation. This regime is not well understood thus both theoretical and experimental study was needed (objectives O2, O5). Moreover, the behaviour of antennas when buried in little known is little known (O6). The novel and/or unconventional methodologies used to characterize the two subjects are detailed in section 1.2 (i) and (ii), and lead to articles: “A.M. Badescu, 2018, The transfer function of a boreholed dipole antenna, IEEE Transactions on Antennas and propagation, vol. 66, no 11, pp 5757-57631”, and “A.M. Badescu, A large scale characterization of the dielectric properties of heterogeneous layered rock salt, submitted for publication at Measurement journal”. Validation of the antenna transfer function model was presented in a conference - A.M. Badescu, I. Mocanu, 2018, The scattering parameters of boreholed antennas in the UHF band, International Conference on Electromagnetics in Advanced Applications (ICEAA), 10-14 Sept. 2018, Cartagena, pp. 99 – 102,
https://ieeexplore.ieee.org/document/8520422(s’ouvre dans une nouvelle fenêtre).
It should be stated that all results rely on performed measurements of the attenuation length in salt (O1) and require the knowledge of the radio noise margin, that has to be extracted from measurements (O3). Preliminary results on the attenuation length (O1) as recorded in “Unirea” salt mine (Slanic Prahova) were presented in a conference -A. Badescu, A. Saftoiu, I. Brancus, D. Stanca, B. Mitrica, 2017, Results on radio attenuation length recorded in a Romanian salt mine, Volume 301 - 35th International Cosmic Ray Conference (ICRC2017) -Session Neutrino. NU-instrumentation, (
https://pos.sissa.it/301/1039/(s’ouvre dans une nouvelle fenêtre)).
Regarding direction B, the optimization of a neutrino detector requires first that the results obtained in “direction A” (propagation and antenna behavior in salt) to be correlated with the radio signal produced by neutrinos’ interaction in salt (O4). The novel and/or unconventional methodologies used to characterize radio emission in neutrinos’ interaction are detailed in section 1.2 (iii), and represented the subject of the article A. Saftoiu, 2018, Estimation of radio emission from neutrino induced showers in rock salt above 10^18 eV, submitted for publication to Astroparticle Physics journal. A preliminary analysis with the overall results for “Unirea” site was carried out in A. Badescu A. Saftoiu, L. Dogariu, 2018, Radio detection of cosmic neutrinos", on “V International Congreso Latinoamericano de Fisica”, 8-12 October 2018, Puebla (O4).
