96 research outputs found
Changes of nuclear spectra under the influence of cosmic radiation
U ovoj disertaciji su prikazani rezultati kompleksnih istraživanja uticaja kosmičkog zračenja na nuklearne spektre na nivou mora. Utvrđivanje specifičnih vremenskih intervala u vremenskom spektru, kojima odgovaraju tačno određene grupe događaja indukovane kosmičkim mionima, omogućava adekvatno odbacivanje ometajućih događaja u željenim energetskim oblastima detektovanih spektara, pri antikoincidentnom režimu rada ultraniskofonskih sistema. U prvom eksperimentu prikazanom u ovoj disertaciji, istraživana je mogućnost vremenskog razlaganja detektovanih događaja, pomoću koincidentnog sistema u čijem sklopu se nalazi HPGe detektor i plastični scintilator, u površinskoj laboratoriji. Ustanovljeno je da se promptni i zakasneli koincidentni događaji između plastičnog “veto” detektora i germanijumskog detektora mogu jasno razdvojiti u dve grupe, za oko 100 ns. Dodatno, zakočno zračenje i anihilacioni događaji mogu se razdvojiti u vremenu od (n,n’) događaja, iako svi ovi događaji pripadaju grupi zakasnelih događaja. Takođe, registrovani su i značajno zakasneli anihilacioni događaji, koji nastaju usled raspada zaustavljenih pozitivnih miona. Drugi eksperiment prikazan u ovoj disertaciji baziran je na ultra-niskofonskom HPGe spektrometru relativne efikasnosti 100%. Dodatkom dva plastična scintilatora i brzo-sporog koincidentnog kola, istraživani su koincidentni događaji između plastičnih scintilatora i HPGe spektrometra. Ovaj spektrometarski sistem MIREDO (Muon Induced Rare Event Dynamic Observatory) prvenstveno je namenjen proučavanju procesa indukovanih kosmičkim mionima u različitim materijalima. Analiza ovakvih interakcija može biti od značaja za ultra-niskofonske eksperimente. Rezultati dobijeni za tri ispitivana materijala, pakovana u Marinelli sud, prezentovani su i diskutovani. U trećem eksperimentu prikazanom u ovoj disertaciji ispitan je potencijalni uticaj solarnih neutrina na izmerenu brzinu radioaktivnog raspada, merenjem varijacija u brzini brojanja 3H metodom tečnog scintilacionog brojanja. Korišćenjem sofisticiranog tečnog scintilacionog spektrometra Quantulus ustanovljeno je da na merenje visokoenergetskog dela 3H spektra može značajno uticati nestabilnost instrumenta. Oscilatorni karakter izmerenog visokoenergetskog dela 3H spektra je registrovan, ali sa veoma malom amplitudom (manjom od 0.5%), koja se ne može jednostavno objasniti samo nestabilnošću instrumenta. Kada je meren ukupan 3H spektar, nisu nađene značajne varijacije u brzini brojanja. Već duže vreme je poznato da je niskoenergetsko gama zračenje kontinualne distribucije prisutno na otvorenom prostoru, u vazduhu na površini Zemlje. U prethodnim istraživanjima pretpostavljano je da ovo zračenje potiče skoro isključivo od gama fotona koji su emitovani usled prirodne radioaktivnosti i potom rasejani u nazad od strane vazduha iznad zemlje. U četvrtom eksperimentu prikazanom u ovoj disertaciji pokazano je da je ovo zračenje (u energetskom regionu 30 keV-300 keV), sa maksimumom na oko 90 keV, u značajnoj meri proizvedeno kosmičkim zračenjem, sa fluksom fotona od oko 3000 m-2s-1. Takođe, ustanovljeno je da dozama opšte populacije doprinosi ovo sveprisutno niskoenergetsko gama zračenja kosmičkog porekla, zajedno sa odgovarajućim fluksom niskoenergetskih elektrona i da ove komponente ukupnih doza indukovanih kosmičkim zračenjem na nivou mora nisu zanemarljive.In this dissertation results of complex research on cosmic-ray impact on nuclear spectra at sea level are shown. The appropriate selection of coincidence time interval in low-background experiments that are based on the rejection of anticoincidence background events is very important for reducing the influence of cosmic-ray muons on acquired spectral data. In the first experiment presented in this dissertation, performed by the coincidence system of an HPGe detector and a plastic detect or in a surface laboratory, the time resolution of the detected events is explored. It is found that the prompt and delayed coincidence events between a plastic veto detector and a Ge detector can be sharply divided for approximately 100 ns in two groups. In addition, the bremsstrahlung and annihilation events can be time-resolved from the (n,n’) events, although all of these events belong to the group of delayed events. Also, substantially delayed annihilation events, which are caused by the decays of stopped positive muons, were detected. The second experiment shown in this dissertation is based on the 100% relative efficiency ultra-low-background HPGe spectrometer. With the addition of two plastic scintillators and a fast-slow coincidence circuit, the coincidence events between the plastic detectors and the HPGe spectrometer have been investigated. This MIREDO (Muon Induced Rare Event Dynamic Observatory) spectrometer system is primarily developed for the study of cosmic muon induced processes in different materials. Exploration of such interactions can be important for ultra-low background experiments. Results derived for three samples, placed in a Marinelli beaker, are presented and discussed. In third experiment shown in this dissertation, the potential influence of solar neutrinos on measured decay rate is investigated by the liquid scintillation measurement of the count rate variations of 3H. Making use of the sophisticated Quantulus liquid scintillation spectrometer, it is found that the measurement of the high-energy tail of 3H spectrum may be significantly influenced by instrumental instability. The oscillatory behavior of measured high-energy tail of 3H spectrum is registered, but with very small amplitude (less than 0.5%), which cannot be easily explained only by instrumental instability. When the total 3H spectrum was measured, no significant variations in the count rate were found. For a long time, it has been known that low-energy continuous gamma radiation is present in open air at the Earth’s surface. In previous investigations it was assumed that this radiation is produced almost exclusively by gamma photons emitted due to the natural radioactivity, which are backscattered by air above ground. In the fourth experiment presented in this dissertation, it is shown that significant amount of this radiation (related to energy region 30 keV-300 keV) that peaks at about 90 keV, is produced by cosmic-rays, with the photon flux of about 3000 m-2s-1. Also, it is found that the contribution of this omnipresent low energy gamma radiation of cosmic-ray origin, including the corresponding low-energy electron flux, to the doses of general population are non-negligible components of overall doses induced by cosmic rays near sea level
Changes of nuclear spectra under the influence of cosmic radiation
U ovoj disertaciji su prikazani rezultati kompleksnih istraživanja uticaja kosmičkog zračenja na nuklearne spektre na nivou mora. Utvrđivanje specifičnih vremenskih intervala u vremenskom spektru, kojima odgovaraju tačno određene grupe događaja indukovane kosmičkim mionima, omogućava adekvatno odbacivanje ometajućih događaja u željenim energetskim oblastima detektovanih spektara, pri antikoincidentnom režimu rada ultraniskofonskih sistema. U prvom eksperimentu prikazanom u ovoj disertaciji, istraživana je mogućnost vremenskog razlaganja detektovanih događaja, pomoću koincidentnog sistema u čijem sklopu se nalazi HPGe detektor i plastični scintilator, u površinskoj laboratoriji. Ustanovljeno je da se promptni i zakasneli koincidentni događaji između plastičnog “veto” detektora i germanijumskog detektora mogu jasno razdvojiti u dve grupe, za oko 100 ns. Dodatno, zakočno zračenje i anihilacioni događaji mogu se razdvojiti u vremenu od (n,n’) događaja, iako svi ovi događaji pripadaju grupi zakasnelih događaja. Takođe, registrovani su i značajno zakasneli anihilacioni događaji, koji nastaju usled raspada zaustavljenih pozitivnih miona. Drugi eksperiment prikazan u ovoj disertaciji baziran je na ultra-niskofonskom HPGe spektrometru relativne efikasnosti 100%. Dodatkom dva plastična scintilatora i brzo-sporog koincidentnog kola, istraživani su koincidentni događaji između plastičnih scintilatora i HPGe spektrometra. Ovaj spektrometarski sistem MIREDO (Muon Induced Rare Event Dynamic Observatory) prvenstveno je namenjen proučavanju procesa indukovanih kosmičkim mionima u različitim materijalima. Analiza ovakvih interakcija može biti od značaja za ultra-niskofonske eksperimente. Rezultati dobijeni za tri ispitivana materijala, pakovana u Marinelli sud, prezentovani su i diskutovani. U trećem eksperimentu prikazanom u ovoj disertaciji ispitan je potencijalni uticaj solarnih neutrina na izmerenu brzinu radioaktivnog raspada, merenjem varijacija u brzini brojanja 3H metodom tečnog scintilacionog brojanja. Korišćenjem sofisticiranog tečnog scintilacionog spektrometra Quantulus ustanovljeno je da na merenje visokoenergetskog dela 3H spektra može značajno uticati nestabilnost instrumenta. Oscilatorni karakter izmerenog visokoenergetskog dela 3H spektra je registrovan, ali sa veoma malom amplitudom (manjom od 0.5%), koja se ne može jednostavno objasniti samo nestabilnošću instrumenta. Kada je meren ukupan 3H spektar, nisu nađene značajne varijacije u brzini brojanja. Već duže vreme je poznato da je niskoenergetsko gama zračenje kontinualne distribucije prisutno na otvorenom prostoru, u vazduhu na površini Zemlje. U prethodnim istraživanjima pretpostavljano je da ovo zračenje potiče skoro isključivo od gama fotona koji su emitovani usled prirodne radioaktivnosti i potom rasejani u nazad od strane vazduha iznad zemlje. U četvrtom eksperimentu prikazanom u ovoj disertaciji pokazano je da je ovo zračenje (u energetskom regionu 30 keV-300 keV), sa maksimumom na oko 90 keV, u značajnoj meri proizvedeno kosmičkim zračenjem, sa fluksom fotona od oko 3000 m-2s-1. Takođe, ustanovljeno je da dozama opšte populacije doprinosi ovo sveprisutno niskoenergetsko gama zračenja kosmičkog porekla, zajedno sa odgovarajućim fluksom niskoenergetskih elektrona i da ove komponente ukupnih doza indukovanih kosmičkim zračenjem na nivou mora nisu zanemarljive.In this dissertation results of complex research on cosmic-ray impact on nuclear spectra at sea level are shown. The appropriate selection of coincidence time interval in low-background experiments that are based on the rejection of anticoincidence background events is very important for reducing the influence of cosmic-ray muons on acquired spectral data. In the first experiment presented in this dissertation, performed by the coincidence system of an HPGe detector and a plastic detect or in a surface laboratory, the time resolution of the detected events is explored. It is found that the prompt and delayed coincidence events between a plastic veto detector and a Ge detector can be sharply divided for approximately 100 ns in two groups. In addition, the bremsstrahlung and annihilation events can be time-resolved from the (n,n’) events, although all of these events belong to the group of delayed events. Also, substantially delayed annihilation events, which are caused by the decays of stopped positive muons, were detected. The second experiment shown in this dissertation is based on the 100% relative efficiency ultra-low-background HPGe spectrometer. With the addition of two plastic scintillators and a fast-slow coincidence circuit, the coincidence events between the plastic detectors and the HPGe spectrometer have been investigated. This MIREDO (Muon Induced Rare Event Dynamic Observatory) spectrometer system is primarily developed for the study of cosmic muon induced processes in different materials. Exploration of such interactions can be important for ultra-low background experiments. Results derived for three samples, placed in a Marinelli beaker, are presented and discussed. In third experiment shown in this dissertation, the potential influence of solar neutrinos on measured decay rate is investigated by the liquid scintillation measurement of the count rate variations of 3H. Making use of the sophisticated Quantulus liquid scintillation spectrometer, it is found that the measurement of the high-energy tail of 3H spectrum may be significantly influenced by instrumental instability. The oscillatory behavior of measured high-energy tail of 3H spectrum is registered, but with very small amplitude (less than 0.5%), which cannot be easily explained only by instrumental instability. When the total 3H spectrum was measured, no significant variations in the count rate were found. For a long time, it has been known that low-energy continuous gamma radiation is present in open air at the Earth’s surface. In previous investigations it was assumed that this radiation is produced almost exclusively by gamma photons emitted due to the natural radioactivity, which are backscattered by air above ground. In the fourth experiment presented in this dissertation, it is shown that significant amount of this radiation (related to energy region 30 keV-300 keV) that peaks at about 90 keV, is produced by cosmic-rays, with the photon flux of about 3000 m-2s-1. Also, it is found that the contribution of this omnipresent low energy gamma radiation of cosmic-ray origin, including the corresponding low-energy electron flux, to the doses of general population are non-negligible components of overall doses induced by cosmic rays near sea level
Applying of Monte-Carlo simulations for in-situ gamma spectrometry
Kako bi se dobile krive efikasnosti detekcije za In-situ merenja gama zračenja poreklom
iz zemljišta, potrebno je izvršiti odgovarajuće Monte-Karlo simulacije. U simulacijama
je korišćena gustina zemljišta od 1,046 g/cm3
, dok je elementalni sastav zemljišta u
kojem se generiše gama zračenje bio: O - 47%, Si - 35%, Al - 8%, Fe – 3,9%, C – 2,1%,
Ca – 1,4%, K – 1,3%, N – 0,6%, Mg – 0,6%, N – 0,1%. Matrica zemljišta je predstavljena cilindričnom zapreminom prečnika 1,5 m i debljine 0,5 m, iznad koje je na visini
od 1 m postavljen germanijumski detektor. Razmatrane su homogene distribucije različitih radionuklida (Ra-226, Th-232, K-40) u matrici zemljišta. U simulacijama su
dobijeni i analizirani odgovarajući gama spektri, koji uz podatke o simuliranim efikasnostima detekcije, omogućuju poređenje sa realnim eksperimentalnim merenjima i
praktičnu primenu simulacionih rezultata.In this work, the Monte-Carlo simulations for In-Situ gamma spectrometry of soil were
performed. The simulated gamma spectrum, originated from K-40, as well as from
members of Th-232 chain, and daughters of Ra-226, was obtained. We obtained the
corresponding detection efficiency curve for HPGe detector, which can be applied for
In-Situ measurement of radionuclide concentration in soil, assuming uniform
radionuclide distribution.Зборник радова : XXIX симпозијум ДЗЗСЦГ : Сребрно језеро, 27-29. септембар 2017. годин
Applying of Monte-Carlo simulations for in-situ gamma spectrometry
Kako bi se dobile krive efikasnosti detekcije za In-situ merenja gama zračenja poreklom
iz zemljišta, potrebno je izvršiti odgovarajuće Monte-Karlo simulacije. U simulacijama
je korišćena gustina zemljišta od 1,046 g/cm3
, dok je elementalni sastav zemljišta u
kojem se generiše gama zračenje bio: O - 47%, Si - 35%, Al - 8%, Fe – 3,9%, C – 2,1%,
Ca – 1,4%, K – 1,3%, N – 0,6%, Mg – 0,6%, N – 0,1%. Matrica zemljišta je predstavljena cilindričnom zapreminom prečnika 1,5 m i debljine 0,5 m, iznad koje je na visini
od 1 m postavljen germanijumski detektor. Razmatrane su homogene distribucije različitih radionuklida (Ra-226, Th-232, K-40) u matrici zemljišta. U simulacijama su
dobijeni i analizirani odgovarajući gama spektri, koji uz podatke o simuliranim efikasnostima detekcije, omogućuju poređenje sa realnim eksperimentalnim merenjima i
praktičnu primenu simulacionih rezultata.In this work, the Monte-Carlo simulations for In-Situ gamma spectrometry of soil were
performed. The simulated gamma spectrum, originated from K-40, as well as from
members of Th-232 chain, and daughters of Ra-226, was obtained. We obtained the
corresponding detection efficiency curve for HPGe detector, which can be applied for
In-Situ measurement of radionuclide concentration in soil, assuming uniform
radionuclide distribution.Зборник радова : XXIX симпозијум ДЗЗСЦГ : Сребрно језеро, 27-29. септембар 2017. годин
Extending and Enhancing the Existing Motorail (Car Trains) System in the Danube River Basin (Drb)
The aim of the project is the enhancement of a greener, innovative and sustainable mobility through the
extension of the existing railway system with as little changes as possible and the development of new
modes of transport, providing a fast and seamless combination of rail and water transport, followed by
short distance travel to the final destination by motorized vehicles or bicycles. This would be achieved
through the extension in the Danube River Basin of the motorail system which allows the transport of cars,
motorbikes and small trailers, creating an efficient, seamless and low-carbon transport network, thus
contributing to the sustainable development of economic competitiveness and growth, of an integrated
European single market and of an open and inclusive society, of tourist accessibility to new countries
Investigations of possible correlations between radionuclides content and geochemical characteristics of Vojvodina soil
U ovom rаdu prikazani su rezultati istraživanja moguće korelаcije geohemijskih
kаrаkteristikа zemljišta i sadržaja prirodnih rаdionuklida 238U, 226Ra, 232Th i 40K, kаo i
radionuklida antropogenog porekla 137Cs u svim geomorfološkim jedinicama zemljišta
na području Vojvodine. Tokom 2001. godine izvršen je detaljan monitoring
radioaktivnosti zemljišta na 50 odabranih lokacija prema tipu zemljišta sa analizom
mehaničkog sastava zemljišta i sadržaja humusa i pristupačnog fosfora i kalijuma.
Kako bi se ispitao potencijаlni uticаj obrаde poljoprivrednog zemljišta i vremenskih
uslovа nа migrаciju i distribuciju rаdionuklidа prisutnih u zemljištu, monitoring
zemljišta je na istim lokacijama ponovljen 2010. godine. Glavni zaključak ovih
istraživanja je da izmerene maksimalne koncentracije aktivnosti radionuklida: 238U (87
Bq/kg), 226Ra (44,7 Bq/kg), 232Th (55,5 Bq/kg) i 137Cs (29 Bq/kg) u profilu zemljišta
dubine 30 cm ne ugrožavaju bezbednost proizvodnje hrane na ovom zemljištu. Utvrđena
je najveća zavisnost koncentracije aktivnosti kalijuma 40K od sadržaja gline u
poljoprivrednom zemljištu.In this paper, we performed, for the first time, detailed study of Vojvodina’s soil in
order to explore possible correlations of soil geochemical characteristics and
radionuclide activity concentrations. The aim of this study is to analyze the content of
natural radioisotopes 238U, 226Ra, 232Th and 40K, as well as artificial radioisotope 137Cs
in all soil types originated from the same parent material – loess. The sampling
locations were selected so that they are proportionately represented all
geomorphological units: two mountains, four loess plateaus, three loess terraces, four
alluvial plains, two sandstone terrains. The process of genesis of soil and cultivation
mode plays a dominant role on the characteristics of the soil. However intensive
agricultural production and the use of high mineral fertilizers have caused that the
same type of soil contains different concentrations of available phosphorus and
radionuclides. Comparison of activity concentrations between different types of soil
confirmed that the presence of clay mostly contributes to radionuclides content in the
soil. The main conclusion is that measured maximal activity concentrations for 238U (87
Bq/kg), 226Ra (44.7 Bq/kg), 232Th (55.5 Bq/kg) and 137Cs (29 Bq/kg) at 30 cm depth
could not endanger the safety of food production
Multivariate analysis application for geogeny radon potential prediction
Geogeni radonski potencijal koji izdvaja radon u podzemnim slojevima kao dominantan
uzrok akumulacije radona u zatvorenim prostorijama i koji je nezavisan od ljudskog
uticaja i vremenski konstantan u geološkim okvirima predstavlja glavni alat za
iznalaženje radonom ugroženih područja. U nedostatku podataka za permeabilnost
zemljišta za radon i malog broja merenja radona u zemljištu, upotrebljena je
multivarijantna analiza velikog broja raspoloživih geohemijskih podataka, merenja
radioaktivnosti zemljišta i koncentracija aktivnosti radona u zatvorenim prostorijama
datih lokacija na području Vojvodine. Nekoliko uporedivih metoda iz ROOT okvira za
analize softverskog paketa TMVA je korišćeno za analizu zavisnosti koncentracije
radona u zatvorenom od mnoštva ulaznih varijabli. BDTG kao najpodobnija metoda je
pokazala da su varijable sa najvećim uticajem na koncentraciju radona u zatvorenim
prostorijama pored sadržaja ukupnog azota, koncentracije aktivnosti radionuklida u
zemljištu na profilu dubine od 30 cm i sadržaj humusa i gline. Dobijeni rezultati
pokazuju dobro slaganje sa nedavnim ispitivanjem emanacije radona iz zemljišta na
području grada Novog Sada.The most dominant source of indoor radon is the underlying soil, so the enhanced levels
of radon are usually expected in mountain regions and geology units with high radium
and uranium content in surface soils. Laboratory for radioactivity and dose
measurement, Faculty of Sciences, University of Novi Sad has rich databases of natural
radionuclides concentrations in Vojvodina soil and also of indoor radon concentrations
for the region of Vojvodina, Northern Province of Serbia. In this paper, we present the
results of correlative and multivariate analysis of these results and geochemical
characteristics of soil in order to estimate the geogenic radon potential. The correlative
and multivariate analysis were done using Toolkit for Multivariate Analysis software
package TMVA package, which uses several comparable multivariate methods for our
analysis. The evaluation ranking results based on the best signal efficiency and purity,
show that the Boosted Decision Trees (BDT) and Multi Layer Preceptor (MLP), based
on Artificial Neural Network (ANN), are multivariate methods which give the best
results in the analysis. The BDTG multivariate method shows that variables with the
highest importance are radio-nuclides activity on 30 cm depth. Moreover, the
multivariate regression methods give a good approximation of radon activity using full
set of input variable
Results of the 2015 national indoor radon intercomparison measurements in Serbia
Results and conclusions of interlaboratory comparison of indoor radon in 2015 in Serbia are presented. The participants were three accredited laboratories from Serbia: Serbian Institute of Occupational Health Dr Dragomir Karajovic, Laboratory for Radioactivity and Dose Measurements at the Faculty of Sciences, University of Novi Sad and Radiation and Environmental Protection Department, Vinca Institute of Nuclear Science. The laboratories make use of the same method for radon measurement, using charcoal canisters according to US Environmental Protection Agency (EPA) protocol 520/5-87-005. Calibration of detection efficiency was performed using EPA radium standard. Radon activity concentrations were determined on the basis of the intensity of short-living radon daughters, Bi-214 and Pb-214, gamma lines. The results of intercomparison were evaluated by using the u-test, which was calculated according to the International Atomic Energy Agency criteria. In this paper, not only limitations but also the advantages and possibilities of application of this method for measuring levels of human exposure to radon are discussed
Multivariate analysis application for geogeny radon potential prediction
Geogeni radonski potencijal koji izdvaja radon u podzemnim slojevima kao dominantan
uzrok akumulacije radona u zatvorenim prostorijama i koji je nezavisan od ljudskog
uticaja i vremenski konstantan u geološkim okvirima predstavlja glavni alat za
iznalaženje radonom ugroženih područja. U nedostatku podataka za permeabilnost
zemljišta za radon i malog broja merenja radona u zemljištu, upotrebljena je
multivarijantna analiza velikog broja raspoloživih geohemijskih podataka, merenja
radioaktivnosti zemljišta i koncentracija aktivnosti radona u zatvorenim prostorijama
datih lokacija na području Vojvodine. Nekoliko uporedivih metoda iz ROOT okvira za
analize softverskog paketa TMVA je korišćeno za analizu zavisnosti koncentracije
radona u zatvorenom od mnoštva ulaznih varijabli. BDTG kao najpodobnija metoda je
pokazala da su varijable sa najvećim uticajem na koncentraciju radona u zatvorenim
prostorijama pored sadržaja ukupnog azota, koncentracije aktivnosti radionuklida u
zemljištu na profilu dubine od 30 cm i sadržaj humusa i gline. Dobijeni rezultati
pokazuju dobro slaganje sa nedavnim ispitivanjem emanacije radona iz zemljišta na
području grada Novog Sada.The most dominant source of indoor radon is the underlying soil, so the enhanced levels
of radon are usually expected in mountain regions and geology units with high radium
and uranium content in surface soils. Laboratory for radioactivity and dose
measurement, Faculty of Sciences, University of Novi Sad has rich databases of natural
radionuclides concentrations in Vojvodina soil and also of indoor radon concentrations
for the region of Vojvodina, Northern Province of Serbia. In this paper, we present the
results of correlative and multivariate analysis of these results and geochemical
characteristics of soil in order to estimate the geogenic radon potential. The correlative
and multivariate analysis were done using Toolkit for Multivariate Analysis software
package TMVA package, which uses several comparable multivariate methods for our
analysis. The evaluation ranking results based on the best signal efficiency and purity,
show that the Boosted Decision Trees (BDT) and Multi Layer Preceptor (MLP), based
on Artificial Neural Network (ANN), are multivariate methods which give the best
results in the analysis. The BDTG multivariate method shows that variables with the
highest importance are radio-nuclides activity on 30 cm depth. Moreover, the
multivariate regression methods give a good approximation of radon activity using full
set of input variable
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