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The 241Am(n,2n) 240Am reaction cross section has been measured at four energies, 10.0, 10.4, 10.8, and 17.1 MeV, by means of the activation technique, relative to the 27Al(n,α) 24Na reaction reference cross section. Quasi-monoenergetic neutron beams were produced via the ²H(d,n) ³He and the ³H(d,n) 4He reactions at the 5.5 MV Tandem T11/25 accelerator laboratory of NCSR "Demokritos". The high purity 241Am targets were provided by JRC-IRMM, Geel, Belgium. The induced γ -ray activity of 240Amwasmeasured with high-resolution high-purity germanium (HPGe) detectors. Auxiliary Monte Carlo simulations were performed with the MCNP code. The present results are in agreement with data obtained earlier and predictions obtained with the EMPIRE code. [ABSTRACT FROM AUTHOR]

Abstract: Quasi-monoenergetic neutron beams, in the energy range 7–11.5MeV, produced via the 2H(d,n) reaction, have been used at the 5.5MV tandem T11/25 Accelerator Laboratory of NCSR “Demokritos”. The flux variation of the neutron beam is monitored with a BF3 detector, while the absolute flux is obtained with respect to reference reactions. An investigation of the energy dependence of the neutron fluence has been carried out using two independent techniques: by a liquid scintillator BC501A detector and deconvolution of its recoil energy spectra performed by means of the DIFBAS code, as well as via the multiple foil activation technique in combination with the SULSA unfolding code. The neutron facility has also been characterized by means of Monte Carlo simulations with MCNP5. [Copyright &y& Elsevier]

Abstract: Fission cross-section measurements with the Fast Ionization Chamber (FIC) at the CERN n_TOF facility were challenged by intense signals due to γ-rays and ultra-relativistic particles from the impact of the 20GeV proton pulses on the neutron spallation target. A method for analyzing the data taken with Flash Analog to Digital Converters (FADC) was developed to treat these problems in an automated way to provide a reliable background subtraction and a fit routine for identifying fission events even at high energies. The analysis is illustrated at the example of the fission cross-section of 238U relative to that of 235U in the energy range from 40keV to 300MeV. [Copyright &y& Elsevier]

Abstract: Systematic experimental and theoretical investigations of the 70,72,73,74Ge(n,p)70,72,73,74Ga reaction cross-sections are presented in the energy range from threshold to about 17MeV neutron energy. The 72,73Ge(n,p)72,73Ga reaction cross-sections were measured from 8.8 to 11.4MeV by using the activation method, relative to the 27Al(n, α)24Na reference reaction. The quasi-monoenergetic neutron beams were produced via the 2H(d,n)3He reaction at the 5MV Van de Graaff (VdG) Tandem T11/25 accelerator of NCSR “Demokritos”. Statistical model calculations using the code EMPIRE (version 2.19) and taking into account pre-equilibrium emission were performed on the data measured in this work as well as on data reported in the literature. [Copyright &y& Elsevier]

The neutron facility at the 5.5 MV tandem T11/25 Accelerator of NCSR “Demokritos” can deliver monoenergetic neutron beams in the energy range from thermal to 450 keV, 4–11.5 MeV and 16–20.5 MeV via the 7Li(p,n), 2H(d,n) and 3H(d,n) reactions, respectively. The flux variation of the neutron beam is monitored by using a BF3 counter and a liquid scintillator BC501A detector. The 232Th(n,2n)231Th and 241Am(n,2n)240Am as well as (n,2n), (n,p) and (n,α) reactions on natural Ge and Hf isotopes, have been investigated from threshold up to 11.5 MeV, by using the activation method. The cross section values have been determined relative to the 197Au(n,2n)196Au, 27Al(n,α)24Na and 93Nb(n,2n) reference reaction cross sections. [ABSTRACT FROM AUTHOR]

Abstract: The GEANT4 Monte Carlo code has been used to simulate γ-ray spectra of natural radionuclides collected by a NaI scintillation detector immersed in seawater. The γ-rays emitted from the decay of 40K, and the series of 232Th and 238U, were used to describe the radioactive water source around the NaI crystal. The simulated γ-ray spectra were compared with real data recorded in situ by a newly constructed NaI spectrometer and were found to be in good agreement. The NaI spectrometer was calibrated in the laboratory in a water tank, before its deployment in seawater. Activity concentrations were deduced from the γ-ray spectra and discussed in comparison with results from the literature. [Copyright &y& Elsevier]

The cross sections of the 191 Ir (n, 2 n) 190 Ir and 191 Ir (n, 3 n) 189 Ir reactions have been determined by means of the activation technique, relative to the 27 Al (n, a) 24 Na reaction, at neutron beam energies higher than 15 MeV. The quasi-monoenergetic neutron beams were produced at the 5.5 MV Tandem T11/25 Accelerator Laboratory of NCSR "Demokritos" by implementing the 3 H (d, n) 4 He reaction. The induced γ -ray activity of the irradiated target and reference foils was measured with high resolution, high purity germanium (HPGe) detectors. The cross section for the high-spin isomeric state (11 -) of the 190 Ir nucleus was determined along with the sum of the ground (4 -), the first (1 -), and the second (11 -) isomeric states. Moreover, the cross section for the production of the ground state of the residual nucleus of (n, 3 n) reaction, 189 Ir, was also estimated. Additionally, cross section theoretical calculations were carried out using the empire 3.2.2 and talys 1.8 codes, in which the input parameters were chosen in such a way as to simultaneously reproduce several experimental reaction channel cross sections in a satisfactory way, namely the (n, 2 n), (n, 3 n), (n, p), (n, a), and (n, total) ones. Similar combination of theoretical model parameters had also been successfully used in the case of the neighboring 197 Au nucleus, and this constitutes an encouraging confirmation of how accurately the theoretical models can reproduce the experimental results in this mass region. [ABSTRACT FROM AUTHOR]

Several cross-section measurements of neutron-induced reactions on Ge found in literature, are performed utilizing natGe targets. The production of the same residual nucleus as the measured one might occur as a result of the unavoidable presence of neighboring isotopes in the same target, acting as a contamination. Corrections must be made based on theoretical calculations and models in order to resolve this problem. The accuracy and limits of a methodology for these "theoretical corrections" are investigated in this work using isotopically enriched targets, which can produce very accurate results without the need for such corrections. Experimental cross-section measurements have been made for the 76Ge(n,2n)75Ge, 72Ge(n, α)69mZn and 72Ge(n,p)72Ga reactions, via the activation technique, with the 27Al(n, α)24Na reaction used as reference, employing both a natGe and isotopically enriched Ge targets. The 3H(d,n)4He (D–T) reaction was used for producing the quasi-monoenergetic neutron beam in the 5.5 MV Tandem Accelerator Laboratory of the National Centre for Scientific Research "Demokritos" in Athens, Greece, at an incident deuteron beam energy of 2.9 MeV. Using HPGe detectors, γ -ray spectroscopy was applied to determine the induced γ -ray activity of the residual nuclei. • Cross section measurements with natural Ge targets need to be corrected for contaminations from neighboring isotopes • A methodology is proposed for the correction of the contribution from parasitic channels • The accuracy and limits of the methodology are investigated with two sets of measurements • Enriched and natural Ge targets were employed for cross-section measurements via the activation technique [ABSTRACT FROM AUTHOR]

The cross section of the 197Au(n,2n)196Au reaction has been determined at six energies ranging from 15.3-20.9 MeV by means of the activation technique, relative to the 27Al(n,α)24Na reaction. Quasimonoenergetic neutron beams were produced via the ³H(d,n)4He reaction at the 5.5 MV Tandem T11/25 accelerator laboratory of NCSR "Demokritos". After the irradiations, the induced γ-ray activity of the target and reference foils was measured with high-resolution HPGe detectors. The cross section for the high spin isomeric state (12-) was determined along with the sum of the ground (2-), the first (5+), and second (12-) isomeric states. Theoretical calculations were carried out with the codes empire 3.2.2 and talys 1.8. Optimum input parameters were chosen in such a way as to simultaneously reproduce several experimental reaction channel cross sections in a satisfactory way, namely the (n,elastic), (n,2n), (n,3n), (n,p), (n,α), and (n,total) ones. [ABSTRACT FROM AUTHOR]

Neutron-induced fission reactions play a crucial role in a variety of fields of fundamental and applied nuclear science. In basic nuclear physics they provide important information on properties of nuclear matter, while in nuclear technology they are at the basis of present and future reactor designs. Finally, there is a renewed interest in fission reactions in nuclear astrophysics due to the multi-messenger observation of neutron star mergers and the important role played by fission recycling in r-process nucleosynthesis. Although studied for several decades, many fundamental questions still remain on fission reactions, while modern applications and the development of more reliable nuclear models require high-accuracy and consistent experimental data on fission cross sections and other fission observables. To address these needs, an extensive fission research programme has been carried out at the n_TOF neutron time-of-flight facility at CERN during the last 18 years, taking advantage of the high energy resolution, high luminosity and wide energy range of the neutron beam, as well as of the detection and data acquisition systems designed for this purpose. While long-lived isotopes are studied on the 185 m long flight-path, the recent construction of a second experimental area at a distance of about 19 m has opened the way to challenging measurements of short-lived actinides. This article provides an overview of the n_TOF experimental programme on neutron-induced fission reactions along with the main characteristics of the facility, the various detection systems and data analysis techniques used. The most important results on several major and minor actinides obtained so far and the future perspectives of fission measurements at n_TOF are presented and discussed. [ABSTRACT FROM AUTHOR]

The fission cross section of 232 Th has been measured at fast neutron energies, using a setup based on Micromegas detectors. The experiment was performed at the 5.5 MV Van de Graaff Tandem accelerator in the neutron beam facility of the National Centre for Scientific Research "Demokritos". The quasi-monoenergetic neutron beams were produced via the 3 H(p,n), 2 H(d,n) and 3 H(d,n) reactions, while the 238 U(n,f) and 235 U(n,f) reactions were used as references, in order to acquire cross-section data points in the energy range 2–18 MeV. The characterization of the actinide samples was performed via α -spectroscopy with a Silicon Surface Barrier (SSB) detector, while Monte Carlo simulations with the FLUKA code were used to achieve the deconvolution of the 232 Th α peak from the α background of its daughter nuclei present in the spectrum. Special attention was given to the study of the parasitic neutrons present in the experimental area, produced via charged particle reactions induced by the particle beam and from neutron scattering. Details on the data analysis and results are presented. [ABSTRACT FROM AUTHOR]

Si(1 0 0) and (1 1 1) crystals were irradiated in the random as well as in the channeling direction, using 5 MeV 19F+ ions, to a maximum fluence of approximately 1×1017 particles/cm2. The occurring deep implanted profiles were subsequently investigated using the Resonant Nuclear Reaction Analysis technique in the energy range Ep=950–1200 keV. The reaction 19F(p,αγ)16O reaction exhibits a strong resonant behavior in the above mentioned energy range, thus providing an excellent tool for the depth profiling of fluorine, yielding minimum detection limits of the order of a few ppm. The occurring profiles are analyzed with SRIM and c-TRIM codes and an attempt is made to explain the characteristics of the experimental spectra, as well as to compare with results already existing in literature. [Copyright &y& Elsevier]

The cross section of the 193Ir(n, 2n)192Ir reaction has been determined by means of the activation technique, relative to the 27Al (n, α ) and 197Au(n, 2n) reference reactions cross sections, at neutron beam energies ranging from 10 to 21 MeV. The quasi-monoenergetic neutron beams were produced at the 5.5 MV Tandem T11/25 Accelerator Laboratory of NCSR "Demokritos" via the 2H(d, n) and 3H(d, n) reactions. The induced γ -ray activity of the irradiated target and reference foils was measured with high resolution HPGe detectors. In order to correct for the contribution of the 191Ir(n, γ )192Ir reaction, which is open to low energy parasitic neutrons, a recently developed analysis method was implemented and it is presented in great detail. Furthermore, cross section theoretical calculations were carried out using the EMPIRE and TALYS codes over a wide energy range. [ABSTRACT FROM AUTHOR]

Abstract Natural radionuclides, present in mining materials, can exhibit elevated values, thus it is of great interest to study their dispersion in mining areas. Radionuclide spatial variations were determined in coastal surface sediments near the mining area of Ierissos Gulf in northern Greece. 226Ra and 235U measured concentrations were compared with the estimations of ERICA Tool, the dispersion patterns were derived and the affected region around the load-out pier area was calculated to be approximately 21 km2. Highlights • 226Ra and 235U spatial distribution indicated elevated values near Stratoni port. • The 226Ra concentrations at Stratoni port were higher than the soil world median. • The applied dispersion model determined the dispersion pattern. • The affected area due to mining activities was estimated approximately 21 km2. [ABSTRACT FROM AUTHOR]

Abstract In counting experiments associated with pulsed sources, a high data collection rate can lead to considerably large counting losses, especially in the case of spallation Time-of-Flight facilities equipped with medium and short flight paths where the research interest is focused on higher neutron energies where counting losses can be quite large due to the higher neutron flux, the more compressed time frame compared to the one on lower energies and the higher cross-section depending on the reaction. Examples of such measurements are the neutron induced fission experiments at the new experimental area EAR-2 at the n_TOF facility at CERN. Although analytical expressions to account for this inefficiency exist in literature, the introduced corrections are not always sufficient to retrieve the true reaction rate, therefore a different approach is mandatory. This work explores the possibility to quantify the counting losses using detector emulation devices and exponential fits in waiting time distributions. The methodology is benchmarked in the test case of the standard 238U(n,f) cross-section with reference to 235U(n,f) for bandwidths up to 1.9 MHz and counting losses that exceed 60%. [ABSTRACT FROM AUTHOR]

Abstract The intensities of γ -rays from the 196m2Au decay adopted in 1998 and 2007 ENSDF evaluations differ up to 20%. Gold samples were irradiated in intensive neutron fluxes with energies up to 35 MeV to produce the isotopes 196Au in all isomeric states. The intensities of gammas from the radioactive decay of the isomer 196m2Au were measured by means of the nuclear γ -ray spectrometry (HPGe detectors) and compared to the existing adopted data. [ABSTRACT FROM AUTHOR]

The U neutron-induced fission cross-section has been measured at incident neutron energies of 452, 550, 651 keV and 7.5, 8.7, 10 MeV using the Li ( p, n) and the H( d, n) reactions, respectively, relative to the U( n, f ) and U( n, f ) reference reactions. The measurement was performed at the neutron beam facility of the National Center for Scientific Research 'Demokritos', using a set-up based on Micromegas detectors. The active mass of the actinide samples and the corresponding impurities were determined via $ \alpha$ -spectroscopy using a surface barrier silicon detector. The neutron spectra intercepted by the actinide samples have been thoroughly studied by coupling the NeuSDesc and MCNP5 codes, taking into account the energy and angular straggling of the primary ion beams in the neutron source targets in addition to contributions from competing reactions ( e.g. deuteron break-up) and neutron scattering in the surrounding materials. Auxiliary Monte Carlo simulations were performed making combined use of the FLUKA and GEF codes, focusing particularly on the determination of the fission fragment detection efficiency. The developed methodology and the final results are presented. [ABSTRACT FROM AUTHOR]

In the present work, the 6 Li(d,d 0 ) 6 Li elastic scattering differential cross sections were measured in the energy range E d,lab = 940 – 2000 keV for Elastic Backscattering Spectroscopy (EBS) purposes, using thin lithium targets, made by evaporating isotopically enriched 6 LiF powder on self-supporting carbon foils, with an ultra-thin Au layer on top for normalization purposes. The experiment was carried out in deuteron beam energy steps of 20 or 30 keV and for the laboratory scattering angles of 125°, 140°, 150°, 160°, and 170°. [ABSTRACT FROM AUTHOR]

A methodology based on γ-spectrometry measurements of untreated coastal water samples is proposed for the direct estimation of coastal residence time of submarine discharged groundwater. The method was applied to a submarine spring at Stoupa Bay covering all seasons. The estimated residence time exhibited an annual mean of 4.6±1.7 d. An additional measurement using the in situ underwater γ-spectrometry technique was performed, in the same site. The in situ method yielded a value of 2.8±0.2 d that was found consistent with the corresponding value derived using the developed lab-based method (3.4±2.0 d) for the same period. [ABSTRACT FROM AUTHOR]

A new approach for calibrating an in situ detection system for measurements in marine sediments has been developed. The efficiency calibration was deduced on full spectral range by Monte Carlo simulations (MCNP5 code) considering a close detector-seabed geometry set-up. Moreover, the influence of the detection efficiency with respect to the variations of the sediment geological characteristics was studied through Monte Carlo simulations. The results of the theoretical approach were compared with experimental calculations in two different real test cases, yielding a satisfactory agreement (up to 10% and 20% for sites 1 and 2 respectively) in the energy range from 351 keV to 2614 keV. For the experimental measurements, the in situ detection system KATERINA was deployed both in the seawater and on the seabed in two different marine environments. The experimental determinations of the detection efficiency were performed by utilizing the acquired data of the deployments, along with additional necessary laboratory measurements. The adopted approach and the obtained results are discussed. [ABSTRACT FROM AUTHOR]

The FLUKA code was implemented to simulate pulse-height spectra of a NaI(Tl) detector (excluding its resolution), considering radioactive sources of naturally occurring and artificial radionuclides present in the marine environment. For this purpose, a user-defined routine was developed for the proper simulation of the emitted γ-rays. The results were compared with simulations performed using the MCNP-CP code. The comparison of the recorded counts in the full-energy peaks, for the high intensity (emission probability >15%) emitted γ-rays for each radionuclide, yielded a satisfactory agreement (calculated ratios from 0.93 ± 0.05 to 1.07 ± 0.02) in all the studied cases. [ABSTRACT FROM AUTHOR]

Marine sediment samples were collected from Ierissos Gulf, N Aegean Sea, close to the coastal mining facilities. Measurements of radionuclide and metal concentrations, mineral composition and grain size distribution were performed. The concentrations of 226 Ra, 235 U and trace metals showed enhanced values in the port of Stratoni compared with those obtained near to Ierissos port. The dose rates received by marine biota were also calculated by the ERICA Assessment Tool and the results indicated no significant radiological risk. [ABSTRACT FROM AUTHOR]

The Full Spectrum Analysis approach was applied to obtain activity concentration estimations for in situ measurements in the marine environment. The ‘standard spectra’ were reproduced using the MCNP-CP code. In order to extract the activity concentrations, χ 2 minimization calculations were performed by implementing the MINUIT code. The method was applied to estimate the activity concentrations for measurements in the marine environment in three different test cases. The estimated activity concentrations were in good agreement with the experimentally derived ones within uncertainties. [ABSTRACT FROM AUTHOR]

The measurement of the 236U(n, f) cross section was attempted with a new MicroMegas detector, based on the Microbulk technology. The incident quasi-monoenergetic neutron beams with energies in the range of 4-10 MeV were produced via the 2H(d, n) reaction at the neutron beam facility of the Institute of Nuclear and Particle Physics at the NCSR "Demokritos" and first results of the analysis are presented. [ABSTRACT FROM AUTHOR]

Lifetimes of yrast and nonyrast states of 102Pd populated via the 92Zr( 13C, 3n) reaction are measured by means of the recoil distance Doppler-shift technique with a Cologne plunger coupled to a GASP spectrometer. The event-by-event data accumulated at 24 plunger distances in the range of 0.1 μm to 9 mm are analyzed using the differential decay curve method. The resulting B(E2) values of the γ transitions depopulating yrast-band members up to the I π = 8+ state are found to deviate significantly from the corresponding predictions of the E(5) critical-point symmetry. [ABSTRACT FROM AUTHOR]

Activity concentration measurements were carried out on the seabed, by implementing the underwater detection system KATERINA. The efficiency calibration was performed in the energy range 350–2600 keV, using in situ and laboratory measurements. The efficiency results were reproduced and extended in a broadened range of energies from 150 to 2600 keV, by Monte Carlo simulations, using the MCNP5 code. The concentrations of 40 K, 214 Bi and 208 Tl were determined utilizing the present approach. The results were validated by laboratory measurements. [ABSTRACT FROM AUTHOR]

The aim of the present work is the study of 137 Cs migration in sediment column taking into account the sedimentation rate in the Amvrakikos Gulf, at the western part of Greece. Marine core sediments were collected and the measurements were performed using the high resolution gamma-ray spectrometry method. The vertical distribution of 137 Cs activity concentration, as part of anthropogenic marine radioactivity, provided averaged sedimentation rate by identifying the depths of activity concentrations due to the Chernobyl accident and the nuclear tests signals. Furthermore, 137 Cs measurements were reproduced using the proposed one-dimensional diffusion–advection model which provides mainly as an output, the sedimentation rate and the average diffusivity of 137 Cs in the sediment column. The proposed model estimates the temporal variation of 137 Cs activity concentration from 1987 (one year after the Chernobyl accident) till today (2014). [ABSTRACT FROM AUTHOR]

Highlights: [•] We studied the 24Mg(d,p0,1,2) reactions at energies and detection angles suitable for NRA. [•] We studied the natMg(d,d0) differential cross section relative to the Rutherford case. [•] We validated the obtained results via benchmarking experiments. [ABSTRACT FROM AUTHOR]

Abstract: The in-situ underwater gamma-ray spectrometry method is validated by inter-comparison with laboratory method. Deployments of the spectrometer KATERINA on a submarine spring and laboratory measurements of water samples with HPGe detector were performed. Efficiency calibrations, Monte Carlo simulations and the Minimum Detectable Activity (MDA) estimations were realized. MDAs varied from 0.19 to 10.4 (lab) and 0.05 to 0.35 (in-situ) Bq/L, while activity concentrations differed from 7% (for radon progenies) up to 10% (for 40K), between the two methods. [Copyright &y& Elsevier]

Cross sections for the 174Hf(n, 2n)173 Hf and 176Hf(n, 2n)175Hf reactions have been measured on the 5.5-MV Van de Graaff tandem accelerator of National Centre for Scientific Research "Demokritos" in Athens, in the neutron energy region from 8.8 to 11.0 MeV, using the activation technique. An experimental method to account for the contamination of the 176Hf(n, 2n) reaction by the 176Hf(n, λ) reaction activated by the parasitic neutrons of the beam is presented. Statistical model calculations have also been performed using the nuclear-reaction codes EMPIRE-II and TALYS. The results and effects of the nuclear input parameters as well as pre-equilibrium emission are discussed in detail. [ABSTRACT FROM AUTHOR]

Abstract: Detectors based on the micromegas principle have already been used in several atomic, nuclear and particle physics experiments. They have also been proposed as one of the options to upgrade the ATLAS muon spectrometer in the very forward/backward region. To meet this end, it is imperative to study their performance in a mixed (neutron and gamma) radiation field. The general-purpose Monte-Carlo code FLUKA has been employed in the present work in order to study the effect of 5.5MeV neutrons impinging on a prototype micromegas detector developed for sLHC. The response of the detector to the photons originating from the inevitable neutron inelastic scattering on the surrounding materials of the experimental facility was also studied, through comparisons with experimental data. [Copyright &y& Elsevier]

Recent accurate data obtained for the isomeric cross section of the 197Au(n, In) reaction provide a valuable opportunity to consider the question of the effective moment of inertia of the nucleus within a local consistent model analysis of all available reaction data for the 197Au target nucleus. Thus, a definite proof of a moment of inertia equal to that of the rigid-body has been obtained for the 196Au nucleus, while indications infer about half the rigid-body for 194Ir. [ABSTRACT FROM AUTHOR]

In the present work, the 197Au(n,2n) reaction cross section is experimentally determined relative to the 27Al(n,α)24Na reaction at incident neutron energies of 9.0-10.5 MeV by means of the activation technique. The quasimonoenergetic fast neutron beam was produced via the 2H(d,n)3He reaction at the 5.5-MV Tandem Van de Graaff accelerator at the National Centre of Scientific Research (NCSR) "Demokritos" and was studied to determine the contribution of background "parasitic" neutrons using the multiple foil activation technique and the SULSA unfolding code. The cross sections for the population of the second isomeric state (12-) of 196Au and the sum of the ground (2-) and first isomeric state (5-) population cross sections were independently determined. Auxiliary Monte Carlo simulations were performed with the MCNP code. Theoretical calculations of the above cross sections in the 8-25 MeV region were carried out with the use of the STAPRE-F, EMPIRE, and TALYS codes, which were also compared in their implementation of the generalized superfluid model. The theoretical results are compared with previous work in the same mass region, and the strong dependence on the level scheme of the nuclei involved was revealed. [ABSTRACT FROM AUTHOR]

Abstract: Boron depth profiling presents strong analytical challenges for all Ion Beam Analysis (IBA) techniques. In the past, both the 11B(p,α o)8Be (NRA) and the 11B(p,p 0)11B (EBS) reactions have been proposed and they seem to be quite suitable for analytical purposes. Nonetheless, both reactions have not been adequately studied in literature (as far as data suitable for material analysis in the backscattering geometry are concerned). Moreover, the existing datasets are relatively discrepant. In an attempt to clarify the situation, both reactions were studied in the present work between 135° and 160°, in steps of 5°, for the proton beam energy range between 2.2 and 4.2MeV, in steps of 50keV. An attempt to explain the occurring results in the framework of the resonance mechanism is also presented, along with a comparison with previously published data. [ABSTRACT FROM AUTHOR]

Abstract: In the present work, new, differential cross-section values are presented for the natK(p, p 0) reaction in the energy range E lab =3000–5000keV (with an energy step of 25keV) and for detector angles between 140° and 170° (with an angular step of 10°). A qualitative discussion of the observed cross-section variations through the influence of strong, closely spaced resonances in the p+ 39K system is also presented. Information has also been extracted concerning the 39K(p,α 0) reaction for E lab =4000–5000keV in the same angular range. As a result, more than ∼500 data points will soon be available to the scientific community through IBANDL (Ion Beam Analysis Nuclear Data Library –http://www-nds.iaea.org/ibandl/) and could thus be incorporated in widely used IBA algorithms (e.g. SIMNRA, WINDF, etc.) for potassium depth profiling at relatively high proton beam energies. [Copyright &y& Elsevier]

Abstract: The differential cross-sections of the 28Si(d,p0,p1,p2,p3) reactions for the determination of the depth distribution of silicon in near-surface layers of materials have been determined in the projectile energy region E d,lab =1500–2000keV. The experiment was carried out in large energy steps of ∼50keV and for six detector angles between 145° and 170° (in steps of 5°). The obtained experimental data, although in principle suitable for Nuclear Reaction Analysis (NRA) studies, they present strong fluctuations, as expected from nuclear physics theory. A qualitative discussion of these fluctuations is also presented. The results are also compared to recent data from literature, taken at 150°. [Copyright &y& Elsevier]

Abstract: The differential cross-sections of the 11B(d, α 0, α 2,p0) reactions for the determination of the depth distribution of boron in near-surface layers of materials have been determined in the projectile energy region E d,lab =900−1200keV. The experiment was carried out in energy steps of 25keV and for four detector angles between 140° and 170° (in steps of 10°). The obtained experimental data are suitable for Nuclear Reaction Analysis (NRA) studies. A qualitative discussion of the observed cross-section variations through the influence of broad resonances in the d+ 11B system is also presented. The results are also compared to data from literature, when present, and are validated through a benchmarking experiment using a high purity thick B4C target. [Copyright &y& Elsevier]

Abstract: A new detection system named “KATERINA” is developed and applied for measuring marine radioactivity using NaI(Tl) as a crystal. This apparatus is designed for qualitative and quantitative radionuclide detection in the marine environment with maximum depth of deployment 400m. A detailed study for the enclosure of the system and for the electronics development is performed. The system offers volumetric activities in Bq/m3 using the marine efficiency calibration, which is measured by dilution of three reference sources (99mTc, 137Cs, and 40K) in a special tank. The calibration procedures for energy, energy resolution and efficiency were analyzed with particular attention to the factors that affect the calibration parameters. The underwater detector is tested in the field for acquiring radon daughters (214Pb and 214Bi) in a region where submarine groundwater discharge exists in the coastal zone. [Copyright &y& Elsevier]

Abstract: The differential cross-sections of the 10B(d,α0) reaction, for the determination of the depth distribution of boron in near-surface layers of materials, have been determined in the projectile energy region E d,lab =900–2000keV. The experiment was carried out in energy steps of 25keV and for eight detector angles between 135° and 170° (in steps of 5°). The obtained experimental data are suitable for nuclear reaction analysis (NRA) studies. The various aspects of the 10B(d,α) reaction, namely the absence of the α1 transition from the experimental spectra, the induced background from three-body kinematics and the 8Be breakup are discussed and analyzed. The results are compared to the ones already existing in the literature and an attempt is made to explain the occurring similarities and differences. A qualitative description of the observed cross-section variations through the influence of overlapping resonances in the d+10B system is also attempted. [Copyright &y& Elsevier]

Abstract: The differential cross-sections of the 10B(d,p0,1,2,3,4–5,6) reactions for the determination of the depth distribution of boron in near-surface layers of materials have been determined in the projectile energy region E d,lab =900–2000keV. The experiment was carried out in energy steps of 25keV and for eight detector angles between 135° and 170° (in steps of 5°). The obtained experimental data are suitable for nuclear reaction analysis (NRA) studies. A qualitative discussion of the observed cross-section variations through the strong influence of overlapping resonances in the d+ 10B system is also presented. [Copyright &y& Elsevier]

We report on proton radiation effects on Si-nanocrystal (Si-NCs) MOS capacitors and nMOS transistors aiming at non-volatile memory applications. Irradiation experiments were conducted on NC MOS capacitors using protons of 1.5 MeV and 6.5 MeV and on NC nMOS transistors using protons of 1.5 MeV. The range of doses investigated was ~1 to ~100 Mrad(SiO2). A 2-D layer of Si NCs with ~ 3 nm mean diameter and 1012 cm-2 surface density was successfully achieved by low-energy (1 keV) ion-beam-synthesis in thin SiO2 layers. After irradiation, programmed capacitors are found to undergo bit flip while programmed transistors are not. Charge retention measurements at room temperature for the write and erase states of irradiated and non-irradiated samples reveal that a significant memory window exists at an extrapolated time of ten years even after an irradiation dose as high as 120 Mrad (SiO2). The flat-band decay rate of the erase state in NC MOS capacitors does not depend on the irradiation-dose while the opposite occurs for the write state which is found to be directly dependent on Dit values after irradiation. These results clearly indicate that NC Non-Volatile Memories (NVM) are promising radiation tolerant devices. [ABSTRACT FROM AUTHOR]

Abstract: Cross section measurements of the 174Hf(n,2n)173Hf reaction have been carried out at the VdG Tandem accelerator of NCSR “Demokritos” in Athens, Greece in the neutron energy range 9.8–11.5MeV, using the activation technique. Statistical model calculations based on the Hauser–Feshbach theory have also been performed by using the code EMPIRE-II with different sets of input parameters. The predictions were compared with the data of the present work as well as with data from literature. [Copyright &y& Elsevier]

Abstract: The response function of a commercial 2in.×2in. BC501A neutron detector has been studied through the general-purpose Monte-Carlo (MC) simulation toolkit GEANT4. For neutron energies below 8MeV, where the dominant detection mechanism originates from the knockout protons, the results of MC calculations reproduce remarkably well the experimental pulse-height spectra. This is not the case, however, at higher neutron energies, where the contribution of heavier charged particles to the detection mechanism becomes significant. The calculated detector efficiency is also compared at three indicative energies to the experimental one via the neutron activation technique. [Copyright &y& Elsevier]

The measurement of the cross section of the reaction 241Am(n,2n)240Am has been performed at neutron energies from 8.8 to 11.1 MeV, implementing the activation technique. The neutron beam was produced at the TANDEM accelerator of NCSR “Demokritos” by the 2H(d,n)3He reaction, using a deuterium gas target. During the 5-day long irradiation, the neutron beam fluctuations were monitored in 100 seconds intervals by a BF3 counter connected with a multiscaling unit. The radioactive target consisted of a 37 GBq 241Am source enclosed in a Pb container. A natural Au foil, a 27Al foil and a 93Nb foil were used as reference materials for the neutron flux determination. After the end of the irradiation the activity induced at the target and the reference foils, was measured off-line by a 56% HPGe detector. [ABSTRACT FROM AUTHOR]

Abstract: Sediment samples have been collected in the Butrint area, located in the south-west Albania to determine the radioactivity levels of 40K, 137Cs, 212Bi, 212Pb, 214Bi, 214Pb, 226Ra and 228Ac on the bed of the lagoon and adjacent sea, using direct counting gamma spectroscopy. The concentration of 137Cs and 40K varied from 2.8 to 37.5Bq/kg and from 266 to 675Bq/kg dry weight (dw), respectively (central values). The average concentrations of 238U and 232Th daughter products varied from 8 to 27Bq/kg and from 13 to 40Bq/kgdw, respectively. The measured 235U activity ranged from 0.7 to 2.5Bq/kgdw. Samples of different sedimentary properties, studied for the radioactivity concentration, revealed an inversely proportional relation between grain size and a linear combination of measured specific activities of 226Ra, 232Th (228Ac, 212Bi and 212Pb), 40K and 137Cs. [Copyright &y& Elsevier]

Abstract: We report on proton radiation tolerance of Si-nanocrystal (Si-NCs) MOS structures aiming at non-volatile memory applications. Si-NCs were formed by low-energy (1keV) ion-beam-synthesis within a 9nm thick SiO2 layer. A 2-D layer of Si-NCs with 3nm mean diameter and 1012 cm−2 surface density was successfully achieved. After fabrication of Al capacitors, samples with and without Si-NCs were 1.5 and 6.5MeV proton were irradiated at doses ranging from 1Mrad (SiO2) to 120Mrad (SiO2). Significant irradiation-dose-dependent shifts are detected in the C–V curves of the NC-MOS cells and programmed cells are found to undergo bit flip. Despite the above, the attainable memory windows after write/erase operations remain unchanged. Retention time characteristics at room temperature for the write and erase states of irradiated and non-irradiated samples reveal that even after an irradiation dose as high as 120Mrad (SiO2) the devices still exhibit long time charge storage behavior. We observe that the erase state flat-band voltage decay rate does not depend on the irradiation-dose while the opposite happens for the write state flat-band voltage decay rate which is found to be directly dependent on D it values giving insight to the physics of the discharging mechanisms. [Copyright &y& Elsevier]

Abstract: Absolute differential cross section measurements of the 12C(d,p1,2,3)13C reactions were performed in the projectile energy region E d,lab =900–2000keV (in steps of 25keV) and for detector angles between 145° and 170° (in steps of 5°) using as targets 99.9% purity self-supported natural carbon (98.9% 12C–1.1% 13C) foils of nominal thickness ca. 1×1018 at/cm2. The overall error in the absolute differential cross section measurements varied around 10–15% in most of the cases. The results, presented in both graphical and tabular forms, are compared with already published data. The strong influence of the resonance mechanism is presented and discussed. [Copyright &y& Elsevier]

Abstract: The differential cross-sections of the 12C(d,p0)13C reaction (applied to the determination of the depth distribution of carbon in near-surface layers of materials) were determined in the projectile energy region E d,lab =900–2000keV (in steps of 25keV) and for detector angles between 135° and 170° (in steps of 5°) using as targets 99.9% purity self-supported natural carbon (98.9% 12C–1.1% 13C) foils of nominal thickness ca. 1×1018 at/cm2. The overall error in the absolute differential cross-section measurements varied between ∼6% and 22%. The results were compared with already published data and the occurring differences were explained. [Copyright &y& Elsevier]

Abstract: In the present work, a detailed study of the natC(d,d0) reaction is presented for E d,lab =900–2000keV (in steps of 25keV) and for detector angles between 145° and 170° (in steps of 5°). This reaction complements the implementation of the 12C(d,p0)13C one, when RBS/NRA spectra are required for carbon profiling. The results are compared to those already existing in literature and an attempt is made to explain the occurring differences. A discussion also follows, concerning the existence of resonances and the reaction mechanisms involved. [Copyright &y& Elsevier]

Abstract: In the present work the radiation damage effects induced by 5.88MeV protons in Si and InP crystals, of ∼400 and 325μm thickness, respectively, are examined and analyzed for high fluences ranging between 1016 and 1018 particles/cm2. The irradiation occurs in the random mode by constantly rotating the targets in order to minimize the channeling perturbations, while the control of the induced damage is performed by utilizing the RBS/C technique on the inverse side of the crystals, implementing the proton beam at a reduced energy (E p =1.2MeV). The experimental results reveal impressive extensions of the damage profiles well beyond the end of range of implanted protons. Conventional theoretical calculations, as well as standard SRIM predictions, seem to underestimate the induced effects. An attempt is made in order to explain the experimental spectra via the adoption of the Coulomb explosion model and the results are compared to other already existing in literature for different beam–target combinations. [Copyright &y& Elsevier]