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A 7Be ion beam of several particle pA at 8 MeV has been produced at the TTT3 tandem of the University "Federico II" in Naples. The 7Be nuclides were formed via the 7Li(p,n)7Be reaction using a metallic Li target and an 11.4 MeV proton beam of 20 μA intensity, delivered by the cyclotron in Debrecen. Methods of hot chemistry were used to extract the 7Be nuclides from the Li matrix and to prepare the 7Be cathodes for the ion sputter source of the tandem. Examples of 7Be beam applications are given. © 2002 Elsevier Science B.V. All rights reserved.

An experiment has been performed at the nuclear power plant of Garigliano (Caserta, Italy), aiming at the measurement of transfer factors of 137Cs and 60Co radionuclides from the irrigation water to a soil-plant system, with particular attention to the influence on such transfers of the irrigation technique (ground or aerial). Tomato plants were irrigated weekly with water contaminated with 137Cs and 60Co (about 375Bq/m2 week), using both irrigation techniques. After 13 weeks, fruits, leaves, stems, roots and soil were sampled, and radionuclide concentrations were measured by high-resolution γ spectroscopy. It was found that the activity allocated to the plant organs is significantly dependent upon the irrigation technique, amounting to 2.1% and 1.6% of the activity given in the cultivation for aerial treatment and 0.4% and 0.3% for the ground treatment, for 137Cs and 60Co respectively. The activity absorbed by plants is allocated mainly in leaves (>55%), while less then 10% is stored in the fruits, for both irrigation techniques. Transfer factors (soil-plant and irrigation water-plant) of tomato plants and of weeds have been determined for 137Cs and 60Co, as well as for natural 40K in the soil. Copyright © 2002 Elsevier Science Ltd.

A small L-shaped short-period seismic array was set up at Etna Volcano to measure the wave velocity and the incoming azimuth of the volcanic tremor generated by the volcanic activity at Etna in non eruptive-conditions. Cross-correlation techniques were used to measure the phase-shifts between the array stations. An approximately N-S direction of the propagation direction was estimated, coincident with the azimuth of the crater area of Etna. An apparent velocity of less than 500 m/s was estimated, suggesting a surface propagation of the tremor waves. Spectral analysis, confirming previous results, shows velocity spectra peaked at approximately 2 Hz. A localized source, coincident with the crater area, agrees with our data and could generate the volcanic tremor at Etna in non-eruptive stages.

Two methods to estimate the geometrical spreading factor n are described; the first is applied to S waves recorded at various distances from the source, whereas the second is applied to coda waves. The direct S-wave method is a new technique which provides the geometrical spreading factor independently of the quality factor Q. This method is based on the double spectral ratio. The coda method provides the geometrical spreading factor along with the Q value. To check their reliability, these methods are applied to real data (from the Andalusian Seismic Network) and to synthetic data. The synthetic test of the coda method indicates that this method to obtain n must not be used to calculate the attenuation factor Q. The results obtained with real data show a geometrical spreading coefficient that is greater than unity and slightly frequency dependent. For S waves, the following frequency dependence was obtained: n=(1.19 ± 0.14)+(0.052 ± 0.007)ƒ and for coda waves, n=1.33 ± 0.19 at 1.5 Hz n=1.57 ± 0.19 at 3 Hz n=1.29 ± 0.24 at 6 Hz The results obtained in this paper (n > 1) suggest a velocity increase with depth and/or strong lateral inhomogeneities which modify the wavefront geometry.

We report a high sensitivity study of actinides content in water and sediment matrices performed for the first time along the Garigliano river, near the nuclear power plant currently undergoing decommissioning, and in the marine environment surrounding the river mouth up to a depth of 100 m. Ultrasensitive accelerator mass spectrometry measurements were carried out to estimate the absolute values of 236U, 238U, 239Pu, and 240Pu concentrations and 236U/238U, and 239Pu/240Pu ratios. The accuracy of the measurements and the spatial distribution of the radionuclides enable us to discriminate the anthropogenic from the natural radionuclide’s contribution to the environmental radioactivity. The results indicate that the contribution to the anthropogenic contamination of past power plant operations is, in most of the examined environmental compartments, negligible compared to fallout. High resolution γ-ray spectrometry measurements for 137Cs and 40K show interesting correlations with the actinides results.

La Comunità Europea ha sottolineato che la formazione iniziale degli insegnanti di scuola primaria in ambito scientifico è una sfida per lo sviluppo: un compito nel nostro Paese assegnato all’università dal 2000 con gli insegnamenti istituzionali di didattica della fisica e laboratorio nei corsi di laurea in Scienze della Formazione Primaria. Il PLS-Fisica, coordinato da Josette Immè, ha posto sempre più attenzione alla ricerca didattica e ha guardato alla qualità anche nell’ambito dell’educazione scientifica di base. Il suo gruppo G6, coordinato da Marisa Michelini, ha approfondito la formazione degli insegnanti. Un’indagine sulla didattica della fisica nella formazione iniziale degli insegnanti di scuola primaria ha messo in luce una ricchezza straordinaria di impostazioni, strategie e metodi, ed un grande bisogno di confronto, effettuato in uno specifico Convegno. Questo fascicolo raccoglie le relazioni più significative selezionate e la sintesi della discussione nei gruppi del Convegno. The European Community has emphasized that the prospective primary teacher education in the scientific field is a challenge for development: a task in our country assigned to the university since from 2000 with the institutional courses of physics education and laboratory in the degree for Primary Teacher Education. The PLS-Physics, coordinated by Josette Immè, has paid more and more attention to educational research and focused to the quality in the field of basic science education too. Its G6 group, coordinated by Marisa Michelini, has deepened the teacher education. A survey on the teaching of physics education for prospective primary teachers has highlighted an extraordinary wealth of settings, strategies and methods, and a great need for comparison, carried out in a specific Conference. This dossier collects the most significant selected contributions and the summary of the discussion in the groups of the Conference.

Anomalies in the radon (222Rn) releases in underground environments are one of the phenomena that can be observed before earthquake occurrence. Continuous measurements of radon activity concentration, and of meteorological parameters that influence the gas emission, were performed in three Slovak and Czech caves during 1-y period (1 July 2016–30 June 2017). The radon activity concentration in caves shows seasonal variations, with maxima reached during summer months. The anomalies in the radon time series are identified using a combination of three mathematical methods: multiple linear regression, empirical mode decomposition and support vector regression. The radon anomaly periods were compared with earthquake occurrences in Europe. Coincidences between both phenomena were found, since all monitored caves reflect contemporaneous local tectonic changes. The results indicate that radon continuous monitoring could assist a better understanding of radon emissions, along active tectonic structures, during seismic events.

This work concerns continuous monitoring of radon and thoron specific activity in soil gas within the framework of identifying possible anomalies. It is based on the analysis of a medium-term data record obtained from soil gas in an area of geophysical interest. The RaMonA spectrometric system is also used to measure the climatic parameters and a specific analysis of the alpha spectra is performed to better determine the alpha lines intensity. Since radon emission is also influenced by meteorological parameters, it is mandatory to differentiate the changes due to the deep phenomena. Different procedures are utilized to reach the above objective: statistical analysis using the Empirical Mode Decomposition technique, the Multiple Linear Regression method and the Remote Radon Estimation by using of the thoron trend to eliminate the locally produced radon fraction. The results of such methods are compared to recognize and to highlight radon anomalies. © The Author 2017. Published by Oxford University Press. All rights reserved.

Radon is considered one of the short- and immediate-term earthquake precursors by International Association of Seismology and Physics of the Earth’s Interior. For this reason, the accurate and reliable measurement of its specific activity in soil gas is mandatory. Since its presence is influenced by many environmental factors, in order to eliminate this influence on the radon activity measurement a multi-parametric and multi-site analysis is necessary. Following this approach, a continuous radon monitoring was carried out in two sites of the Phlegrean Fields caldera (Campania, Italy) using the RaMonA system, which also allows for the measurement of temperature, relative humidity and pressure. In particular, the dependence of measured radon specific activity on the meteorological conditions was studied using the multiple linear regression method. The analysis was implemented also by testing data averages on different timescales. In this paper, the results of a preliminary analysis performed on data collected throughout 2012 are presented; the outcomes obtained allow to emphasize site-specific behavior and to discriminate apparent radon “anomalies” of climatic origin from those tied to the phenomena occurring in the earth’s crust. The method employed showed its usefulness by removing the effects of meteorological conditions and thus to better identify the possible radon anomalies caused by seismo-volcanic activity. The peculiarities of the different sites and some correlations with earthquakes are discussed.

Lake Patria is a mesoaline coastal lagoon that develops along the coastal zone of the Volturno River plain (Campania, South Italy). The lagoon is a saline to brackish water body, ca. 2.0 long, and 1.5 km wide, with an average water depth of 1.5 m, reaching a maximum of ca. 3.0 m. The freshwater input into the lagoon is provided by a series of fresh to brackish water channels and small springs, landwards, while a permanent connection with the Tyrrhenian Sea is provided by a channel, 1.5 km long and a few meters wide. Drilling data from 12 boreholes acquired in the study area indicate that Lake Patria is a man-modified remnant of a larger lagoonal area that developed during the last millennia along the Campania coastal zone within an alluvial delta system at the mouth of the paleo-Volturno River. Sedimentological and stratigraphic analyses of drill cores suggest that the lower Volturno delta plain developed in the last 6000 years. Depositional conditions during this period were dominated by flood-plain and alluvial plain settings, with transition to coastal bars and associated back-barrier coastal lagoons. Lake Patria started evolving at an early stage of the Volturno delta plain formation as a consequence of foreshore deposits damming-up by littoral drift. The first marine layers display a radiocarbon age of ca. 4.8 ka BP and overlie a substrate represented by volcaniclastic deposits, originated by the Campi Flegrei, and associated paleosols. The lagoonal succession cored at Lake Patria may be interpreted as the result of a dynamic equilibrium between marine influence and riverine input into the lagoonal system through time, and has been tentatively correlated with the major climatic changes that occurred during Mid–Late Holocene. Insights into the recentmost evolution of the coastal lagoon of Lake Patria are provided by the GIS-based analysis of the physiographic changes of the region conducted on a series of historical topographic maps dating back to the early XVII century. Particularly, the superposition of historical cartography reveals the secular trends in the change of coastal environments and the role of human modification of natural habitats over the last 400 years.

The recent interest for measuring 220Rn concentrations in air and the following development of the correspondent measurements techniques require the development of standards for the calibration and characterization of the instruments. Due to the short half-life (55.6 s) of the 220Rn, the techniques usually adopted for the production of 222Rn sources and relative reference atmospheres are not always valuable. The development of a metrology for 220Rn needs, therefore, the realization of new methods for the preparation of such standards, whose starting point is the availability of reliable sources that allow to obtain stable over time thoron activity. These conditions can be achieved using a long living solid source containing a known activity of one precursor of the thoron able to release gas continuously. To produce from this stable source a reference atmosphere with a uniform activity concentration other steps are necessary. At our laboratory a program for the development of a methodology to realize, starting from a 232Th source, a known thoron activity concentration is in progress. In this paper the first phase of the procedure, consisting on the study of measurement techniques of the exhaled thoron activity, will be presented and discussed. A source of 220Rn has been realised starting from a sample containing 232Th, placed in a PTFE container that allows to operate the source in sealed or unsealed configuration. The so assembled source has then been measured by gamma ray spectroscopy with a HP-Ge whose efficiency was measured using a certified source in the geometry and density similar to those of the sample. Since it is difficult to evaluate the thoron exhaled fraction without interferences from the not exhaled one, an eligible methodology has been set up to reach this result, which consists of two different phases. The first is carried out on the sealed source to take information on the total amount of the 220Rn in equilibrium with 232Th. The second one is performed with the source in ???open??? status, at least four days after its opening, using a suction system which takes away the released amount of the gas and allows the measurement of the thoron retained fraction. 220Rn exhaled amount is finally obtained by subtracting from the value of the total activity, the partial one. This procedure has been repeated many times at same environmental conditions to verify its reproducibility. Next step will be the characterization of the source at various values of temperature, humidity and pressure. After the characterization, the source will be used to realize thoron atmospheres in the chamber that is actually used at our laboratory to calibrate active and passive radon measuring devices.

A complete and detailed analysis of alpha spectra from the (222)Rn and (220)Rn progenies was performed by newly developed software. The software identifies the alpha peaks, performs appropriate fits and calculates the net area and its uncertainty, considering the entire background. The deconvolution of the overlapped peaks of (218)Po and (212)Bi allows us also to evaluate their minimum detectable area. The efficiency of the electrostatic detection method was recalculated and new useful considerations on the collected alpha emitters were made.

Accelerator mass spectrometry (AMS) is presently the most sensitive technique for the measurement of long-lived actinides, e.g. 236U and 239Pu. A new actinide line is in operation at the Center for Isotopic Research on Cultural and Environmental heritage (CIRCE) in Caserta, Italy. Using the actinide line a uranium mass sensitivity of around 4 μg has been reached measuring with a 16-strip silicon detector, and a 239Pu background level of below 0.1 fg has been obtained. In this work we also discuss preliminary results for environmental and structural samples from in and around the Garigliano nuclear power plant (GNPP), presently in the decommissioning phase. Measurements on environmental samples from the vicinity of the plant allow the assessment of contamination, if any, over the years. Measurements of structural samples from the plant are relevant to the optimization of the decommissioning program for the GNPP.

The assessment of the radiological impact of a decommissioning Nuclear Power Plant is presented here through the results of an environmental monitoring survey carried out in the area surrounding the Garigliano Power Plant. The levels of radioactivity in soil, water, air and other environmental matrices are shown, in which {\alpha}, {\beta} and {\gamma} activity and {\gamma} equivalent dose rate are measured. Radioactivity levels of the samples from the Garigliano area are analyzed and then compared to those from a control zone situated more than 100 km away. Moreover, a comparison is made with a previous survey held in 2001. The analyses and comparisons show no significant alteration in the radiological characteristics of the area surroundings the plant, with an overall radioactivity depending mainly from the global fallout and natural sources., Comment: 13 pages, 6 figures, 2 tables

We present a first effort to investigate (236)U in the environment near a shutdown nuclear power plant far away from highly contaminated sites, by using accelerator mass spectrometry. The detection limit of about 1pg (236)U allowed us to identify a minimal increase of the (236)U/(238)U isotopic ratio correlated to a peak of (137)Cs in river sediments downstream of the nuclear power plant, and to detect anthropogenic (236)U also upstream, where it is probably not related to the power plant but to global fallout. The (236)U content shoved variations of the (236)U/(238)U isotopic ratio in relation to the chemical-physical characteristics of the sediments. This demonstrates the potential of (236)U as an environmental tracer, and as an indicator for releases from nuclear facilities.

A radon calibration facility was developed at Naples University (Italy). It consists of an exposure chamber, a radon reference monitor and an apparatus suitable for radon circulation and air climatic control. The parameters that are possible to change and control are carrier gas, radon activity, gas pressure, temperature, and humidity. The characterization of the facility is actually underway to verify its reliability and stability with respect to various parameters of interest.

A new AMS system has been installed at Center for Isotopic Research on Cultural and Environmental Heritage (CIRCE) in Caserta/ Italy. It was built by National Electrostatics Corp. Middleton, WI/USA, and arrived at CIRCE in the middle of January 2005; the installation and the acceptance tests were completed at the end of February 2005. At first, the system is intended for Radiocarbon AMS; for future Al and Be AMS only minor upgrades are needed and the magnets are designed to bend heavy isotopes like Uranium. Concerning Radiocarbon AMS, the first measurements of unknown samples, prepared in the internal preparation laboratory, already yielded results of high precision and C-14 dating is in full swing. (c) 2007 Elsevier B.V. All rights reserved.

To better understand the influence of air parameters such as pressure, humidity and temperature on the counting efficiency of a radon monitor based on solid state silicon detectors and radon daughter electrostatic collection, a number of experimental and theoretical studies have been performed. This study has been carried out using a multiparameter acquisition system used to monitor radon, temperature, pressure and relative humidity. Results show that air humidity and temperature inside the cell influence radon daughter collection in a significant way. For the tested cell, a decrease of the 218Po counting efficiency vs. humidity and temperature increase was measured in the ranges from 10% to 90% and from 15 degrees C to 35 degrees C, respectively. These effects were also theoretically studied by using Monte-Carlo software, which takes into account electrostatic collection of radon daughters in the cell, by considering the recombination process as a function of climatic parameters. A satisfactory agreement was obtained between experimental measurements and theoretical calculations.

An experiment was performed at the Nuclear Power Plant of Garigliano (Caserta, Italy) to study the transfer of radionuclides from a contaminated soil to a lettuce crop and to check the validity of the generally accepted assumption of constant uptake. Measurements of specific activities of 137Cs, 60Co, and 40K were periodically performed by sampling plants during a growth period of 48 days. The specific activity was analysed as a function of plant mass and growth time to gain information on the dependence of radionuclide sorption on plant growth stage. The results (time-dependent uptake rate) were interpreted using a dynamic model which generalizes the transfer factor. In this model, the time dependence of the transfer factor is characterized by three parameters obtained from a non linear least-squares fit to the data. The resulting values were found to be dependent on the radionuclide. The relative growth rate of lettuce plants plays an important role in the transport process: maximum radionuclide transport occurs at 12 d for 60Co and 137Cs and 28 d for 40K. © 2002 Elsevier Science Ltd. All rights reserved.

Controlled 222Rn+220Rn mixed atmospheres have been realised introducing calibrated sources in a stainless steel chamber. An electrostatic alpha monitor internal to the chamber has been used for an accurate discrimination of alpha peaks due to the products of the two isotopes. In the chamber, different specific activities are achieved in order to test the response of the internal reference instrument and to evaluate the possible interferences due to contemporary presence of both radon isotopes. Results show that: (i) the atmospheres are very stable, (ii) the monitor is adequate for their control because the various alpha lines are well evaluated and (iii) using Tyvek® filter, the efficiency of monitor is stable and constant vs. activity.

The reliability and accuracy of the methodology based on using LR-115 track detectors for radon measurements have been studied by determining the dependence of their calibration factors on radon exposure at levels reaching 13 MBq m−3 h. This factor results not constant and demonstrated a decreasing exponential trend vs. exposure that has been explained in terms of the saturation effect and verified using a numerical simulation. This dependence does not affect the parameter that normalizes track density vs. film thickness. This parameter results constant and equal to - 0.30±0.02 cm−2/µm in the 300–8000 kBq h m−3 exposure range.

Optimization of in soil air radon monitoring using thoron and radon and thoron parents

The operation of Nuclear Power Plants and atmospheric tests of nuclear weapons performed in the past, together with production, transport and reprocessing of nuclear fuel, lead to the release into the environment of a wide range of radioactive nuclides, such as uranium, plutonium, fission and activation products. These nuclides are present in the environment at ultra trace levels. Their detection requires sensitive techniques like AMS (Accelerator Mass Spectrometry). In order to perform isotopic ratio measurements of the longer-lived actinides, e.g., of 236U relative to the primary 238U and various Pu isotopes relative to 239Pu, an upgrade of the CIRCE accelerator (Center for Isotopic Research on Cultural and Environmental Heritage) in Caserta, Italy, is underway. In this paper we report on the results of simulations aiming to define the best ion optics and to understand the origin of possible measurement background. The design of a high resolution TOF-E (Time of Flight-Energy) detector system is described, which will be used to identify the rare isotopes among interfering background signals.

A radon survey was carried out in 30 schools located in the metropolitan area around Naples, Italy. Radonconcentration was measured using the SSNTD (Solid State Nuclear Track Detectors) method with LR115 detectors. Time integrated measurements covered two consecutive 6-month periods at different locations inside the school buildings: classrooms, laboratories and offices. Data distribution is well fitted by a log-normal curve. The arithmetic mean annual radonconcentration is 144 Bq m−3, the geometric mean is 86 Bq m−3; the standard deviations are respectively 7 Bq m−3 and 3. The fractions of rooms where radonconcentrations exceed the reference levels of 200, 400 and 500 Bq m−3 are 21.3%, 7.6% and 4.5% respectively. The results show that radonconcentration in scientific laboratories and in offices is higher than in classrooms.

(137)Cs and (60)Co, two of the radionuclides more representative of discharges from nuclear facilities, are of interest for radiological protections because of their great mobility in biosphere and affinity with biological systems. The aim of the present work is the investigation of the possible influence of the vertical distribution of (137)Cs and (60)Co in soil upon their uptake by lettuce as function of plant's growth. An experiment ad hoc has been carried out in field conditions. The results show that (i) the transfer of (137)Cs and (60)Co from soil to lettuce is independent by their distribution in soil, (ii) the soil-plant transfer factors of (137)Cs and (60)Co show a similar trend vs. growth stage, (iii) the (40)K transfer factor trend is different from those of anthropogenic radionuclides, and (iv) (137)Cs and (60)Co specific activities are about 1Bq/kg, in the mature vegetable with soil activity from 9 to 21kBq/m(2).

Human bones recovered from the archaeological site of Pontecagnano (Salerno, Italy) have been studied to reconstruct the diet of an Etrurian population. Two different areas were investigated, named Library and Sant’ Antonio, with a total of 44 tombs containing human skeletal remains, ranging in age from the 8th to the 3rd century B.C. This time span was confirmed by 14C dating obtained using Accelerator Mass Spectrometry (AMS) on one bone sample from each site. Atomic Absorption Spectrometry (AAS) was used to extract information about the concentration of Sr, Zn, Ca elements in the bone inorganic fraction, whilst stable isotope ratio measurements (IRMS) were carried out on bone collagen to obtain the δ13C and δ15N. A reliable technique has been used to extract and separate the inorganic and organic fractions of the bone remains. Both IRMS and AAS results suggest a mixed diet including C3 plant food and herbivore animals, consistent with archaeological indications. #Revised version of a paper presented at ...

RaMonA (radon monitoring and acquisition) is a compact device, developed by our laboratory, having the aim to perform the continuous monitoring of radon daughters collected on a silicon detector by an electrostatic field. In this paper the latest version of the system is presented, obtained after an updating process developed with these main objectives: the design of a new electronic project, the realisation of the complete integration of all function in a single module, the installation on board of a microprocessor hosting the software necessary to run the system, and the substitution of the serial port with an Ethernet interface, allowing the driving of the station from any point of the net. The prototype of this new RaMonA has been successfully tested and many stations are actually under construction to be installed in a series of schools to realise a network for the radon monitoring in the soil.

The environmental radioactivity (ENVIRAD) project involves students of Italian secondary schools with the aim to make them acquainted with the radon measurement techniques. The first step of the project has consisted of the introduction of the participants into some themes not treated in usual curricula to supply the student with the cultural skill to carry out survey about radon concentrations in the school and eventually in other buildings. The second ENVIRAD's part is the creation of a network for the continuous on-line measurements of radon exhalation from soil for geophysical applications. The feasibility of the project has been verified by I-year work with a pilot school during the season 2002/2003. In the following year, 18 schools will join the project. (c) 2004 Published by Elsevier B.V.

A compact device suitable to acquire and display, at the same time, radon concentrations in a given atmosphere, and the environmental parameters characterising the atmosphere, is presented and described. It consists of two main blocks: (i) a detection section including a set of sensors for measuring pressure, humidity and temperature, and a set of silicon surface barrier detectors mounted in electrostatic cells collecting the ionised radon daughters; (ii) a single NIM module featuring an eight channel 12 bit ADC and the linear electronics to shape the signals from the silicon detectors. The system is controlled by a computer via a RS232 port. The software, implemented in Visual Basic, allows to display the energy distribution of the pulses coming from the alpha detectors and to initialise and control all phases of the acquisition. The results of preliminary tests show the high reliability of the system.

For improved measurements of the key astrophysical reaction View the MathML source in inverse kinematics, a recoil separator ERNA is developed to detect directly the View the MathML source recoils with nearly 100% efficiency. Since the View the MathML source projectiles and the View the MathML source recoils have essentially the same momentum and since the View the MathML source ion beam emerging from an accelerator usually passes through a momentum filter, a sufficient absence of an View the MathML source beam contaminant in the View the MathML source ion beam is of utmost importance for ERNA. In the present work, a Wien filter together with a ΔE−E telescope are used to investigate the beam contaminants accompanying a momentum-filtered View the MathML source ion beam and to measure the level of ion beam purification achievable with the Wien filter.

The radon emanation and exhalation rates from soil samples were measured using an electrostatic collector coupled to a silicon detector. The radon progenitor activities ( 226 Ra and 232 Th) of soil samples were determined using γ-ray spectroscopy with a germanium detector. The radon emanation and exhalation rates have been measured accurately and rapidly. Measurements of soil samples having different physical properties were performed. Data analysis methods were developed to identify the effect of grain size and porosity of soil samples. The results confirm interesting dependencies of emanated radon as a function of two soil parameters.

A system with several lines for the preparation of graphite targets for radiocarbon analysis has been built at the new accelerator mass spectrometry (AMS) facility in Caserta, Italy. Special attention has been paid in the design to the reduction of background contamination during sample preparation. Here, we describe the main characteristics of these preparation lines. Results of tests performed to measure 14C background levels and isotope fractionation in several blank samples with the Caserta AMS system are presented and discussed. © 2007 by the Arizona Board of Regents on behalf of the University of Arizona.

Actinide isotopes are present in environmental samples at ultra-trace levels (236U concentration is quoted to be on the order of pg/kg or fg/kg). Their detection requires the resolution of mass spectrometry (MS) techniques, but only accelerator mass spectrometry (AMS) has the sensitivity required. In order to perform the isotopic ratio measurements of actinides, such as 236U/238U, an upgrade of the Center for Isotopic Research on Cultural and Environmental Heritage accelerator (CIRCE) in Caserta, Italy, has been performed. The system was originally equipped for radiocarbon AMS measurements. The main difficulty of AMS measurement of 236U is the intense neighboring beam of 238U. Although most of the 238U ions are suppressed by means of magnetic and electrostatic elements, a small fraction of this intense beam can interfere with the rare isotopes. This paper reports the preliminary results of the 236U/238U isotopic ratio measurement limit (