bluuebunny/crossref_metadata_2025 huggingface dataset:
Fisher kernels match deep models
Authors: Azim T.
Published: February 2017

Deep models have recently shown improved performance on numerous benchmark tasks in computer vision and machine learning. The availability of huge amount of digital data, possibility of massively parallel computations on graphics processing units and the development of advance optimisation techniques have pushed the limits of the deep learning framework by superseding the performance of state‐of‐the‐art research, in specific the kernel methods. This research proposes a novel connection between the two paradigms of research and shows empirical evidence to emphasise that the knowledge learnt from one domain could be supplemented with the significant properties of the other domain to achieve the best of both the worlds. The proposed hybrid methodology illustrates the advantages of deep architectures for kernel methods by showing significant improvement in the classification performance on benchmark tasks with kernel methods. It is shown empirically that the results achieved are either better or competitive to the leading benchmarks from support vector machines and deep models.
Performance analysis of cognitive relay sharing systems with bidirectional primary transmissions under Nakagami‐m fading†
Authors: Solanki Sourabh , Upadhyay Prabhat K.
Published: February 2017

This study investigates the performance of a cognitive relay sharing system (CRSS) wherein two primary users (PUs) exchange the information bidirectionally. The overall transmission in CRSS takes place using an amplify‐and‐forward‐based multiple access broadcast protocol. Herein, besides assisting the transmission of secondary users, the relay also provides an aid for the bidirectional communication between PUs. In addition, the secondary system employs an opportunistic user scheduling with multiple destinations to further ameliorate the performance of secondary network. Here, by considering Nakagami‐m fading channels, the authors derive novel closed‐form expressions of outage probability (OP) and average error probability for both primary and secondary systems. Based on the derived expressions of OP, the authors also quantify the average system throughput. With bidirectional primary communications, the proposed CRSS offers higher spectral efficiency and incentivises the secondary communication through multiuser diversity. Finally, numerical and simulation results are provided for the validation of the theoretical analysis.
Simplified swarm optimisation for the solar cell models parameter estimation problem
Authors: Yeh Wei‐Chang , Lin Peijie , Huang Chia‐Ling
Published: February 2017

Solar energy applications and research are becoming increasingly popular, and photovoltaics (PVs) are among the most significant solar energy applications. To simulate and optimise PV system performance, the optimal parameters of the solar cell models should be estimated exactly. In this study, improved simplified swarm optimisation (iSSO), a recently introduced soft computing method based on simplified swarm optimisation, is proposed to minimise the least square error between the extracted and the measured data for the solar cell models parameter estimation of the single‐ and double‐diode model problems. Based on the new all‐variable difference update mechanism and survival of the fittest policy, the proposed algorithm is able to find an improved approximation for estimating the parameters of single‐ and double‐diode solar cell models. As evidence of the utility of the proposed iSSO, the authors present extensive computational results for two benchmark problems. The comparison of the computational results supports the proposed iSSO algorithm outperforms the previously developed algorithms for all of the experiments in the literature.
Linear Rogowski coil
Authors: Nassisi V. , Delle Side D.
Published: February 2017

Nowadays, the employment and development of fast current pulses require sophisticated systems to perform measurements. Rogowski coils are used to diagnose cylindrical shaped beams; therefore, they are designed and built with a toroidal structure. Recently, to perform experiments of radiofrequency biophysical stresses, flat transmission lines have been developed. Therefore, in this work we developed a linear Rogowski coil to detect current pulses inside flat conductors. The system is first approached by means of transmission line theory. We found that, if the pulse width to be diagnosed is comparable with the propagation time of the signal in the detector, it is necessary to impose a uniform current as input pulse, or to use short coils. We further analysed the effect of the resistance of the coil and the influence of its magnetic properties. As a result, the device we developed is able to record pulses lasting for some hundreds of nanoseconds, depending on the inductance, load impedance, and resistance of the coil. Furthermore, its response is characterized by a sub-nanosecond rise time (∼100 ps). The attenuation coefficient depends mainly on the turn number of the coil, while the fidelity of the response depends both on the magnetic core characteristics and on the current distribution along the plane conductors.
Influence of chemistry, interfacial width, and non-isothermal conditions on spatially heterogeneous activated relaxation and elasticity in glass-forming free standing films
Authors: Mirigian Stephen , Schweizer Kenneth S.
Published: February 2017

We employ the Elastically Collective Nonlinear Langevin Equation (ECNLE) theory of activated relaxation to study several questions in free standing thin films of glass-forming molecular and polymer liquids. The influence of non-universal chemical aspects on dynamical confinement effects is found to be relatively weak, but with the caveat that for the systems examined, the bulk ECNLE polymer theory does not predict widely varying fragilities. Allowing the film model to have a realistic vapor interfacial width significantly enhances the reduction of the film-averaged glass transition temperature, Tg, in a manner that depends on whether a dynamic or pseudo-thermodynamic averaging of the spatial mobility gradient is adopted. The nature of film thickness effects on the spatial profiles of the alpha relaxation time and elastic modulus is studied under non-isothermal conditions and contrasted with the corresponding isothermal behavior. Modest differences are found if a film-thickness dependent Tg is defined in a dynamical manner. However, adopting a pseudo-thermodynamic measure of Tg leads to a qualitatively new form of the alpha relaxation time gradient where highly mobile layers near the film surface coexist with strongly vitrified regions in the film interior. As a consequence, the film-averaged shear modulus can increase with decreasing film thickness, despite the Tg reduction and presence of a mobile surface layer. Such a behavior stands in qualitative contrast to the predicted mechanical softening under isothermal conditions. Spatial gradients of the elastic modulus are studied as a function of temperature, film thickness, probing frequency, and experimental protocol, and a rich behavior is found.
LabVIEW-based control and acquisition system for the dosimetric characterization of a silicon strip detector
Authors: Ovejero M. C. , Pérez Vega-Leal A. , Gallardo M. I. , Espino J. M. , Selva A. , Cortés-Giraldo M. A. , Arráns R.
Published: February 2017

The aim of this work is to present a new data acquisition, control, and analysis software system written in LabVIEW. This system has been designed to obtain the dosimetry of a silicon strip detector in polyethylene. It allows the full automation of the experiments and data analysis required for the dosimetric characterization of silicon detectors. It becomes a useful tool that can be applied in the daily routine check of a beam accelerator.
Dimension of discrete variable representation for mixed quantum/classical computation of three lowest vibrational states of OH stretching in liquid water
Authors: Jeon Kiyoung , Yang Mino
Published: February 2017

Three low-lying vibrational states of molecular systems are responsible for the signals of linear and third-order nonlinear vibrational spectroscopies. Theoretical studies based on mixed quantum/classical calculations provide a powerful way to analyze those experiments. A statistically meaningful result can be obtained from the calculations by solving the vibrational Schrödinger equation over many numbers of molecular configurations. The discrete variable representation (DVR) method is a useful technique to calculate vibrational eigenstates subject to an arbitrary anharmonic potential surface. Considering the large number of molecular configurations over which the DVR calculations are repeated, the calculations are desired to be optimized in balance between the cost and accuracy. We determine a dimension of the DVR method which appears to be optimum for the calculations of the three states of molecular vibrations with anharmonic strengths often found in realistic molecular systems. We apply the numerical technique to calculate the local OH stretching frequencies of liquid water, which are well known to be widely distributed due to the inhomogeneity in molecular configuration, and found that the frequencies of the 0-1 and 1-2 transitions are highly correlated. An empirical relation between the two frequencies is suggested and compared with the experimental data of nonlinear IR spectroscopies.
Reaction dynamics of Al + CO2 → AlO + CO studied by a crossed-beam velocity map imaging technique
Authors: Honma Kenji , Hirata Daiki
Published: February 2017

The oxidation reaction of a gas-phase aluminum atom by a carbon dioxide molecule was studied by employing a crossed-beam technique at two collision energies: 27.9 and 52.8 kJ/mol. A (1 + 1) resonance-enhanced multiphoton ionization via the D2Σ+−X2Σ+ transition of AlO was applied to ionize the product. For several rotational levels of AlO in the vibrational ground state, time-sliced ion images were measured for the first time, and the angular-kinetic energy distributions were determined. All angular distributions showed forward and backward peaks; the forward peaks were more pronounced than the backward ones at the two collision energies. The product kinetic energy showed rather narrow distributions whose peaks appeared at near to the highest limit estimated from the available energies. The rotational distributions of the counter product CO, derived from the kinetic energy distributions, suggested that only a limited number of rotational states were formed and that a small amount of energies go into this mode. These results suggested that the reaction proceeds via a short-lived intermediate in which the O–C–O keeps a nearly linear structure.
Femtosecond laser induced structural dynamics and melting of Cu (111) single crystal. An ultrafast time-resolved x-ray diffraction study
Authors: Li Runze , Ashour Omar A. , Chen Jie , Elsayed-Ali H. E. , Rentzepis Peter M.
Published: February 2017

Femtosecond, 8.04 keV x-ray pulses are used to probe the lattice dynamics of a 150 nm Cu (111) single crystal on a mica substrate irradiated with 400 nm, 100 fs laser pulses. For pump fluences below the damage and melting thresholds, we observed lattice contraction due to the formation of a blast force and coherent acoustic phonons with a period of ∼69 ps. At larger pump fluence, solid to liquid phase transition, annealing, and recrystallization were measured in real time by monitoring the intensity evolution of the probing fs x-ray rocking curves, which agreed well with theoretical simulation results. The experimental data suggest that the melting process is a purely thermal phase transition. This study provides, in real time, an ultrafast time-resolved detailed description of the significant processes that occur as a result of the interaction of a femtosecond light-pulse with the Cu (111) crystal surface.
Frozen Waves following arbitrary spiral and snake-like trajectories in air
Authors: Dorrah Ahmed H. , Zamboni-Rached Michel , Mojahedi Mo
Published: February 2017

We present, in theory and experiment, a class of non-diffracting and self-healing optical beams whose central spot can be designed to follow off-axis curved trajectories. The intensity of the generated waveform can traverse a spiral path with the possibility of reversing its handedness and changing its longitudinal intensity pattern with propagation, on demand. The central spot can also be designed to evolve from a straight to a curved snake-like trajectory and vice versa. Such flexible level of control can be useful for many applications in atomic guiding, optical trapping, and material processing.
Improved integration of ultra-thin high-k dielectrics in few-layer MoS2 FET by remote forming gas plasma pretreatment
Authors: Wang Xiao , Zhang Tian-Bao , Yang Wen , Zhu Hao , Chen Lin , Sun Qing-Qing , Zhang David Wei
Published: February 2017

The effective and high-quality integration of high-k dielectrics on two-dimensional (2D) crystals is essential to the device structure engineering and performance improvement of field-effect transistor (FET) based on the 2D semiconductors. We report a 2D MoS2 transistor with ultra-thin Al2O3 top-gate dielectric (6.1 nm) and extremely low leakage current. Remote forming gas plasma pretreatment was carried out prior to the atomic layer deposition, providing nucleation sites with the physically adsorbed ions on the MoS2 surface. The top gate MoS2 FET exhibited excellent electrical performance, including high on/off current ratio over 109, subthreshold swing of 85 mV/decade and field-effect mobility of 45.03 cm2/V s. Top gate leakage current less than 0.08 pA/μm2 at 4 MV/cm has been obtained, which is the smallest compared with the reported top-gated MoS2 transistors. Such an optimized integration of high-k dielectric in 2D semiconductor FET with enhanced performance is very attractive, and it paves the way towards the realization of more advanced 2D nanoelectronic devices and integrated circuits.
Hypothetical planar and nanotubular crystalline structures with five interatomic bonds of Kepler nets type
Authors: Kochaev Aleksey I.
Published: February 2017

The possibility of metastable existence of planar and non-chiral nanotubular crystalline lattices in the form of Kepler nets of 34324, 3342, and 346 types (the notations are given in Schläfly symbols), using ab initio calculations, has researched. Atoms of P, As, Sb, Bi from 15th group and atoms of S, Se, Te from 16th group of the periodic table were taken into consideration. The lengths of interatomic bonds corresponding to the steadiest states for such were determined. We found that among these new composed structures crystals encountered strong elastic properties. Besides, some of them can possess pyroelectric and piezoelectric properties. Our results can be used for nanoelectronics and nanoelectromechanical devices designing.
A bridge between undergraduate and doctoral degrees
Authors: Hodapp Theodore , Woodle Kathryne Sparks
Published: February 2017

Initiated in 2013, the American Physical Society Bridge Program has assisted more than a hundred underrepresented racial and ethnic minority students to pursue PhDs in physics.
Final report on COOMET key comparison of capacitance at 10 pF (COOMET.EM-K4)
Authors: Velychko O , Akhmadov O
Published: February 2017

An intercomparison of capacitance at 10 pF has taken place within the framework of COOMET. The intercomparison, piloted by State Enterprise 'Ukrmetrteststandard'-UMTS (Ukraine), has involved seven laboratories, including one who is a member of another regional metrological organization-APMP (NMIJ/AIST, Japan). The results presented in this report appear to show that there are significant differences between some laboratories' representations of the farad. However, the agreement demonstrated by the intercomparison provides confidence in maintaining traceability for the capacitance at 10 pF. Proposed to link the results from this key comparison to the CCEM-K4 comparison. VNIIM (Russia) and PTB (Germany) are linking NMIs as far as they participated in CCEM-K4.

Main text

To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/.

The final report has been peer-reviewed and approved for publication by the CCEM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).
Final report on COOMET supplementary comparison of capacitance at 100 pF (COOMET.EM-S4)
Authors: Velychko O , Akhmadov O
Published: February 2017

An intercomparison of capacitance at 100 pF has taken place within the framework of COOMET. The intercomparison, piloted by State Enterprise 'Ukrmetrteststandard'-UMTS (Ukraine), has involved seven laboratories, including one who is a member of another regional metrological organization-APMP (NMIJ/AIST, Japan). The results presented in this report appear to show that there are significant differences between some laboratories' representations of the farad. However, the agreement demonstrated by the intercomparison provides confidence in maintaining traceability for the capacitance at 100 pF.

Main text

To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/.

The final report has been peer-reviewed and approved for publication by the CCEM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).
Accidental Gamma Irradiation Dosimetry Using Clothing
Authors: Kamenopoulou V. , Barthe J. , Hickman C. , Portal G.
Published: February 2017

Further studies have been pursued in order to develop a method for gamma accident dosimetry using clothing. A non-destructive technique, electron spin resonance (ESR), is used to obtain dosimetric information. Several different fabrics and various physical and chemical treatments are investigated.
Neutron Dosimetry Studies Using the New Chalk River Nuclear Laboratories Bubble-Damage Detector
Authors: Perks C.A. , Devine R.T. , Harrison K.G. , Goodenough R.J. , Hunt J.B. , Johnson T.L. , Reil G.L. , Schwartz R.B.
Published: February 2017

Chalk River Nuclear Laboratories are developing a new, direct reading, neutron detector called the bubble-damage detector. This paper reports on experiments to evaluate it for neutron dosimetry. The neutron energy responses, for detectors irradiated in free air and for detectors attached to phantoms, were measured using a variety of neutron sources. The results indicate that the detectors have an acceptable dose equivalent response to neutrons with energies in the range 3 keV - 14 MeV. The bubble-damage detector has a very high neutron sensitivity (up to 1.0 ± 0.2 bubbles.µSv-1), zero background and negligible sensitivity to gamma rays. However, the detectors suffered a substantial loss in neutron sensitivity with storage time before irradiation, a large variation in sensitivity with temperature during irradiation, and poor stability of the bubbles after irradiation. If these problems can be overcome with production detectors, this type of detector will have considerable potential for applications in neutron dosimetry where rapid readout of the dose equivalent is required.
Dead-time Corrections and Effects of Dead-Time on the Counting Statistics of G-M Counters Used in Mixed Neutron-Gamma Radiation Dosimetry
Authors: Sabol J.
Published: February 2017

A new method for the dead-time correction based on the measurement of time intervals between the successive detector pulses is described. The final result in terms of true count rate or total number of pulses can be directly obtained without prior knowledge of the dead-time involved. For this purpose a formula derived from modified Poisson statistics is proposed. The method may be utilised especially in dosimetry systems with G-M counters, exhibiting a non-extended dead-time, used for evaluation of the dose caused by a gamma component in mixed neutron-gamma radiation fields. In addition, the count rate error due to the dead-time effects is also taken into consideration.
Variation of Time-Averaged Outdoor Radon Concentrations over a Distance of About 50 Kilometres
Authors: Put L.W. , de Meijer R.J.
Published: February 2017

Time-averaged outdoor radon concentrations (TORC) have been measured over a one year period in the northeastern part of the Netherlands using passive dosemeters. The grid size in these measurements was 5 km. Values obtained in this investigation correspond well with those obtained in a national survey a few years earlier. No indication was found for rapid changes in the TORC values. At all 43 locations total ? ray intensities were also measured. TORC values and ? ray intensities seem to be slightly correlated with soil composition; no clear correlation exists between TORC and ? ray intensity.
Variation of Time-Averaged Indoor and Outdoor Radon Concentrations with Time, Location and Sampling Height
Authors: Put L.W. , de Meijer R.J.
Published: February 2017

To study the long-term variations of indoor and outdoor radon concentrations time-averaged radon concentrations were measured in and around two dwellings over a period of almost five years. The integration times for passive dosemeters ranged from 4 to about 18 months. Also studied was the variation of the concentration in a living room and a crawl space as a function of the position of the dosemeters. The outdoor radon concentration was determined as a function of sampling height and position relative to building materials. The relevance of the results for the measuring practice and for the evaluation of radon surveys is discussed.
Radon Control and Remedies in Buildings
Authors: Cliff K.D. , Britten J.R. , Dixon D.W. , Gardner P.H. , Richardson P.A.T.
Published: February 2017

The Government in the UK has decided that remedial action to reduce exposure from radon daughters in existing houses should be taken where the annual effective dose equivalent exceeds an Action Level of 20 mSv. Future houses should be designed so that the annual dose from radon daughters does not exceed an Upper Bound of 5 mSv. The Ionising Radiations Regulations 1985 impose statutory control on exposure to radon daughters in the workplace. Field and laboratory studies of effective methods to reduce radon concentrations in buildings in the UK are in progress. An account of this work is presented.
Studies of PTTL and OSL in TLD-400
Authors: Allen P. , McKeever S.W.S.
Published: February 2017

We present data on the mechanisms of phototransferred thermoluminescence (PTTL) and optically stimulated luminescence (OSL) in single crystal CaF2:Mn (3%) and in TLD-400 chips. The TL peak under study is the main dosimetry peak near 275 oC. From measurements of the excitation spectra for PTTL it is found that the maximum transfer rate occurs when the wavelength of the illuminating light is 280 nm. This corresponds to the wavelength of an absorption peak which remains in the sample following initial irradiation and heating to 400 oC. This wavelength also corresponds to a complex peak which is seen in the OSL excitation spectra of irradiated samples. Possible models based on optical stimulation of electrons and diffusion of excited F centres are discussed.
Dosimetric Characteristics of Specially Prepared Clothing Material
Authors: Lapraz D. , Iacconi P. , Alessandri M.F. , Barthe J. , Portal G.
Published: February 2017

Some of the characteristics are presented of a textile sample specially prepared according to our specifications, for accident dosimetry of appropriate workers. The estimation of doses is made be thermally stimulated exoelectron emission (TSEE), thermoluminescence (TL) and photo-induced thermoluminescence (PITL).
Dosimetric Characteristics of LiF:Mg,Cu,P TL Phosphor Prepared at ININ, Mexico
Authors: Azorin J. , Gutiérrez A. , Niewiadomski T. , González P.
Published: February 2017

Among the various TL dosemeters produced in this laboratory, LiF:Mg,Cu,P has turned out to be of special interest. The preparation and dosimetric characteristics of this new LiF dosemeter are reported and a description of the preparation method is presented. Its glow curve structure and TL response dependence with gamma exposure, re-usability, fading, sensitivity and energy dependence are studied along with those of LiF (TLD-100). The new LiF:Mg,Cu,P exhibits a dosimetric peak at 475 K. Its TL response is linear from 100 µGy. It is stable and re-usable without significant loss of sensitivity. Its sensitivity is about 25 times higher than that of commercial LiF (TLD-100) and its energy dependence similar. These and other characteristics render this dosemeter useful in diverse applications of radiation dosimetry.
An Experimental Evaluation of the Reproducibility of TLD Systems Using LiF and BeO
Authors: Scarpa G. , Alberici A. , Ledda S. , Klamert V.
Published: February 2017

A preliminary report is given on the results of an investigation carried out by four Italian TLD laboratories on the problem of reproducibility of TL systems. Commercial LiF:Mg,Ti chips and BeO discs were chosen as they are the most widely used detectors on personal dosimetry services. Two Harshaw 2000 B + C, one Harshaw 2000-D (Atlas) and two Vinten Toledo readers were used by the participating laboratories. The same set of 30 LiF chips and 30 BeO discs, individually coded, was used, in a sequence, by all laboratories, following a carefully agreed protocol concerning: total number of annealing-irradiation-preheat-readout cycles, irradiation dose, type of source, annealing and preheat procedure, time intervals and reading technique. Five out of the 30 detectors of each type were read without irradiation, to evaluate the background signal of the system. According to a simplified model, the overall variability of a response of a given TL system was assumed to have only two components: (1) the variability really due to the fluctuations of the light output of the detector, per unit dose; and (2) the variability due to the fluctuations of the reader response. Among other results, the present investigation shows that the variability of response of a TL system is primarily due to the instability of the reader.
The NRPB PADC Neutron Personal Dosemeter: Recent Developments
Authors: Tanner R.J. , Gilvin P.J. , Steele J.D. , Bartlett D.T. , Williams S.M.
Published: February 2017

NRPB have been operating a substantial neutron personal dosimetry service using PADC for over three years. Amongst recent developments is a re-designed holder, composed of nylon-6 and comprising two snap-together halves. Results are presented of thorough tests of the re-designed dosemeter, including studies of environmental effects and radon sensitivity, and the dependence of response on neutron energy and on angle of incidence. Quality control procedures for the acceptance of PADC plastic are also described, and results comparing the performances of PADC manufactured from two different monomers are presented.
Lyoluminescence of Calcium Carbonate and Possible Applications in the Dating of Loess and Soils
Authors: Copty-Wergles K. , Nowotny R. , Hille P.
Published: February 2017

Lyoluminescence (LL) during the dissolution in HCl of calcite and aragonitic snail shells irradiated with 60Co ? rays was investigated. In the dose range of 100 to 3000 Gy the LL response of analytical grade calcite powder samples is sub-linear but shows no saturation. The influence of solvent concentration, temperature and of dissolved nitrogen on LL yield was studied. The traps responsible for LL are not stable under illumination. Annealing experiments indicate the existence of several different traps and the possibility of electron transfer between them.
The Effect of Age on the Absorption and Intestinal Retention of Ingested Radionuclides
Authors: Harrison J.D. , Fritsch (INVITED) P.
Published: February 2017

The available data from animal experiments and limited human studies indicate that increased absorption of ingested radionuclides in the new born is a general phenomenon. The greatest absorption is observed immediately after birth, followed generally by a progressive reduction over the suckling period. For the actinides and other elements studied, adult values are reached by about the time of weaning on to solid foods. However, for essential elements such as iron and calcium, and related elements such as cobalt, strontium and lead, increased absorption may also occur at later stages in response to changes in physiological demand. The Nuclear Energy Agency has recommended fractional absorption (f1) values for the first year of life using a general approach of assuming a factor of ten increase for elements with adult values of 0.001 or less and a factor of two increase for values up to 0.5. A Task Group of ICRP Committee 2, currently considering age-dependent doses from ingested radionuclides, has endorsed this general approach. However, changes during childhood have been taken into account for lead, strontium, barium and radium.
A One Trap, Two Luminescence Centre TL Model
Authors: Franklin A.D. , Hornyak W.F. , Chen R.
Published: February 2017

The differential equations governing the behaviour of a model of the TL process in the presence of two luminescence centres and only one thermally active electron trap have been solved numerically. An additional deep trap not communicating thermally with the conduction band is included. At low temperatures and, for glow curves, for low temperature rise rates the well known quasi-steady state regime applies. At sufficiently high temperatures, however, exhaustion of the electrons in the active trap may take place and the quasi-steady state conclusions may be no longer valid. The simultaneous influences of both luminescence centres must be taken into account. In the quasi-steady state regime the familiar methods of determining the activation energy E from the data are valid even in the presence of two luminescence centres, provided exhaustion effects are not present and provided the recombination rates for the two luminescence centres do not differ by too much.
Alpha Particle Induced TL Supralinearity in TLD-100: Dependence on Vector Properties of the Radiation Field
Authors: Rosenkrantz M. , Horowitz Y.S.
Published: February 2017

The linear/supralinear behaviour of the TL dose response in LiF:Mg,Ti (TLD-100) and its dependence on ionisation density is a fairly unique phenomenon which cannot be explained by conventional atomic 'conduction band/valence band' kinetic models. The Track Interaction Model (TIM) provides the microscopic framework which, when coupled with other appropriate physical mechanisms (spatial localisation of traps and recombination centres, competing centres, variations in the capture cross sections with temperature, etc.) can be used to describe all the dominant features of the TL supralinearity of LiF:Mg,Ti and similar TL systems. The unique feature of the TIM applied to alpha particles is that it is an integral approach with only one free parameter, the average charge carrier migration distance in the luminescence recombination stage. Although the TIM provides a comprehensive description of the mechanisms underlying supralinearity in TLD-100, definitive unambiguous proof of its validity has been lacking. The present paper reports on the experimentally measured dependence of 4 MeV alpha particle induced supralinearity of glow peaks 5, 7, 8, and 9 on the vector properties of the radiation field. The onset of supralinearity is shifted to lower fluence levels by a factor 3-4 in 'near-isotropic' geometry compared to 'near-parallel' irradiation geometry. No other experimental or radiation field parameter is changed. The only reasonable explanation is that the track interaction is enhanced in 'near-isotropic' geometry due to the approximately 50:1 aspect ratio of the alpha particle track. These results are considered 'proof-positive' or undeniable proof of the dominant importance of track interaction in TLD-100 supralinearity.
Combined TSL-ESR MgO Detectors for Ionising and UV Radiations
Authors: Kortov V.S. , Milman I.I. , Monakhov A.V. , Slesarev A.I.
Published: February 2017

MgO single crystals doped with iron after a reducing thermochemical treatment can be used for measuring ionising and UV radiation doses with simultaneous readout of TSL and ESR. A single maximum at 400 K is observed in TSL spectra. Its intensity grows in linear fashion with the radiation dose from 10-4 to 104 Gy for X radiation and from 10-1 to 103 µj.cm-2 for UV radiation (wavelength = 250 nm). Dose dependence of the ESR signal intensity caused by Fe3+ ions is linear from 1 to 104 Gy for X irradiation. Under UV irradiation the ESR signal is registered starting from doses of 2 x 102 µJ.cm-2. The upper level of the measured dose exceeds 105 µJ.cm-2. Complete anneal of the ESR signal is observed at 950 K. This makes it possible to use the detectors when measuring irradiation doses at higher temperatures.
Retrospective Accident Dosimetry Using Environmental Materials
Authors: Haskell (INVITED) E.H.
Published: February 2017

Retrospective dosimetry of radiation accidents can be accomplished with the aid of environmental materials which were exposed during the time of the accident. The primary requirements for such dosemeters include: (1) the absence of a saturating natural dose accumulated over geological time periods, (2) the ability to retain a record of the accident exposure with negligible fading over the time interval between exposure and measurement and (3) the ability to determine the cumulative dose from natural radiation sources. Natural dosemeters often meeting these requirements are the quartz inclusions found in fired ceramics such as bricks, tiles and porcelain plumbing fixtures. The firing during manufacture erases the prior geological dose. The total cumulative dose (DT) accrued from natural sources as well as the accidental dose is measured using thermoluminescence or other dosimetry techniques. The cumulative natural dose since firing (DN) can de determined with a knowledge of the age of the material (time since firing) together with measurements of dose rate due to internal as well as external sources. The accidental dose is derived by subtracting the natural from the total accrued dose (DT-DN). In cases of high accidental exposures or low natural doses due to the selection of young samples, the natural dose can be estimated or neglected. Three dosimetry techniques, the pre-dose TL technique, the 'high temperature' TL technique (quartz inclusion or fine grain) and more recently the optically stimulated luminescence technique may be applied to quartz grains from the same samples to provide estimates of accrued dose which are largely independent of one another. A non-destructive technique, electron paramagnetic resonance spectroscopy (EPR) may also be applied to these materials in situations of moderately high exposure. An additional advantage of EPR is that it may be applied to biological materials, most notably the hydroxyapatite of tooth enamel. This paper briefly reviews past uses of dosimetry techniques in accident situations, discusses the types of information which may be obtained with their use and the basic methodologies of some of the procedures.
An Interim Protocol for the Mitigation of Radon in Non-Residential Buildings
Authors: Wilson D.L. , Dudney C.S. , Gammage R.B.
Published: February 2017

To date, the US Environmental Protection Agency has not published guidance for radon testing, diagnostics, or mitigation within large, non-residential buildings. Current research indicates that large buildings may contain construction features or mechanical systems that could inhibit the installation or operation of a mitigation system. Health and safety issues such as asbestos and fire codes may further interfere with the installation process. Studies also show that elevated radon can be restricted to a particular area or room within a building and not be uniformly distributed. A four-step, sequential protocol has been developed to address these issues and facilitate large building radon mitigation.
Where's the Radon? The Geographic Information System in Washington State
Authors: Coleman K.A. , Hughes G.C. , Scherieble F.J.
Published: February 2017

As Washington's lead agency for radon issues, the Department of Health (DOH) is developing the analytical basis for establishing a public health policy regarding radon. The Geographic Information System (GIS) is a fundamental step in this analytical process to develop a map of the potential for indoor radon occurrence. The GIS analysis will take into account geology, geography, topography, soil permeability, indoor test results, population density and distribution, and housing. In addition, DOH is working to aid policy makers and residents by comparing residential exposures to the lowest exposure range at which miners evidenced excess lung cancers. This approach is a departure from the commonly used risk assessments that extrapolate from high to low exposure, and will help determine how many Washington residents are at risk. In conclusion there is an examination of Washington's radon prescriptive construction standards for residences.
The Department of Energy's Radon Testing Programme
Authors: Dudney C.S. , Wilson D.L. , Gammage R.B. , Scott H.L.
Published: February 2017

The US Department of Energy (DOE) conducted an initial study of indoor radon in buildings under its control in response to Public Law 100-551, the Indoor Radon Abatement Act, enacted by the US Congress in 1988. Other federal agencies have also conducted radon surveys. This paper presents an overview of the results from radon testing of several thousand buildings ranging from 100 m2 to over 10,000 m2 in size. In addition, results from groups of buildings have been examined, classified according to ventilation and usage characteristics. So far, there is no apparent difference among building classes. The paper also discusses a proposal for phased radon surveys. It is suggested that first-phase results can be used to identify facilities with radon problems. In the second phase, measurements can be made at a much higher sampling density at facilities with radon problems. The results of the second phase are expected to identify all buildings in need of mitigation.
Pitfalls in the Use of 57Co Flood Sources
Authors: Busemann-Sokole E , Kugi A , Bergmann H
Published: February 2017

Long-lived 57Co flood sources, used for routine quantitative monitoring of scintillation camera flood-field uniformity, have recently become available with nominal activities of 370 MBq and higher. Non-uniformity problems have been observed. These are presumably related to high overall count rates from 57Co and other radioactive cobalt isotopes present as impurities. This was investigated in five different cameras from four manufacturers using three cobalt sources of different ages and strengths. Count rates were measured within the energy range 30 keV to 1200 keV, and compared to the count rates in the 122 keV photopeak window. For a new flood source placed on the collimator, the overall count rate was about 400% of the photopeak window count rate. About 200% was due to high energy photons with energies above 134 keV. The count rate diminished when the source was moved away to a distance of 50 cm. The high energy contribution was less with the older sources, due to the faster decay of the cobalt impurities. Uniformity images were visually and quantitatively evaluated. Non-uniformity patterns were observed. These were dependent on the actual source area viewed by the camera, the age of the source, the distance of the source from the collimator, and the type of camera. Problems can be circumvented by purchasing lower activity sources (180 MBq), and increasing the source-collimator distance. Uniformity must first be carefully assessed before the source is put into use.
Late Effects of Low Level Irradiation
Authors: Pelevina I.I. , Gotlib V.Ja. , Afanasjev G.G.
Published: February 2017

The effect of low level irradiation may be delayed for many generations in HeLa cells. When the progeny of irradiated cells was seeded 15-30 generations after irradiation (0.1-0.5 Gy 60Co ? rays, 0.3 Gy.min-1; or in the Chernobyl zone 0.1-0.5 Gy, 0.003-0.005 Gy.h-1) they formed clones with a reduced number of cells. There are giant cells and cells with micronuclei in such clones. Progeny of surviving HeLa cells showed a reduced cloning efficiency and enhanced radiosensitivity. These results suggest that residual damage may by carried by surviving progeny over many generations and expressed as changes which lead to delayed reproductive death.
Thermoluminescence Kinetics at the Extreme Heating Rates Possible with Thermal Laser Stimulation
Authors: Kelly P. , Braunlich P. , Abtahi A. , Jones S.C. , deMurcia M.
Published: February 2017

Heating rates approaching 105 K.s-1 are possible by direct non-contact laser heating whereby the energy from the laser beam can be coupled directly to the phonon system of the thermoluminescence material. In addition to describing phenomena such as shifts of glow peak temperatures, loss of glow spectrum resolution and anticipated decrease of luminous efficiencies due to extreme heating rates, we will discuss problems associated with the common presuppositions of classical thermoluminescence kinetics: thermal equilibrium and detailed balance. Theoretical and experimental results will be compared.
Use of Cotton in Accident Dosimetry
Authors: Barthe J. , Iacconi P. , Lapraz D. , Petel M. , Keller P. , Portal G.
Published: February 2017

In this paper we present preliminary phenomenological and feasibility studies of accident dosimetry based on absorbed dose by cotton fibres. Cotton fibres are very often the main constituent of clothing. It should thus be possible to estimate the dose received by an individual exposed to ionising radiation and not wearing an individual dosemeter. Cotton fabric was chosen for its well known structure and its suitability for studies by simple techniques such as exoelectron emission from surface defects selected for its high sensitivity.
Low Dose Measurements with Lyoluminescence Materials
Authors: Busuoli G. , Monteventi F.
Published: February 2017

The paper reports LL measurements for which the reader assembly has been improved in order to standardise the measurement procedures and to limit the uncertainties. Materials, like L-glutamine and N-acetyl-D-glucosamine, in addition to mannose and glucose, have been tested using sensitised solutions heated and kept at constant temperature during the read-out process. Mannose is rather insensitive even using sensitised solutions (minimum detectable dose: 0.1 Gy), while the detection limit for glucose and N-acetyl-D-glucosamine is of the order of 2 mGy using luminol as the sensitiser. The reproducibility is within ±10% for doses of the order of 50 mGy for glucose. Measurements with diphenylisobenzofuran (DPBF) have shown small amplification of the LL signal.
Highlights of the Sixth International Intercomparison of Environmental Dosemeters
Authors: Gesell T.F. , Kalbeitzer F.L. , de Planque G.
Published: February 2017

The sixth in a series of intercomparisons of environmental dosemeters was conducted at the United States Department of Energy's Idaho National Engineering Laboratory during the late summer and early fall of 1982. These studies permit assessment of the state of the art of environmental dosimetry and allow participants to compare their results with those of their counterparts at other laboratories. Data were obtained for 169 sets of dosemeters submitted by 119 laboratories from 27 countries. Frequency distributions of the results for the various test categories are provided and the results are tabulated by dosemeter type. Performance as a function of calibration technique and other factors is noted.
Properties of Sintered CaSO4:Dy Dosemeters
Authors: Drazic G. , Trontelj M.
Published: February 2017

Glow curves of dosemeters sintered from a mixture of CaSO4 and Dy2O3, in addition to low temperature peaks, also display a sensitive peak at 300 oC, which seems to be due to the incorporation of Dy in the CaSO4 lattice at high sintering temperatures. The influence of chemical composition and sintering temperature on this peak was studied. It was found that the 300 oC peak is not influenced by monovalent impurities. The fading rate of this peak is also small at elevated temperatures.
A Comparative Study of Different (n,alpha) Converter Materials Placed in Contact with Cellulose Nitrate Track Etch Detectors for Neutron Detection
Authors: Niwa T. , Koga T. , Morishima H. , Kawai H. , Nishiwaki Y.
Published: February 2017

Different (n,a) converter materials placed in contact with cellulose nitrate detectors were tested as thermal neutron detectors. A plastic sheet doped with 1% boron, a solidified boron oxide plate, a single crystal plate of boron oxide and a single crystal plate of lithium fluoride were used as converter materials. After thermal neutron irradiation in the low power research reactor of the Institute, the cellulose nitrate detectors were etched in alkaline solution. The etched holes on the films were counted with a spark counter. The single crystal of lithium fluoride was found to be the most sensitive converter for the detection of thermal neutrons. A linear relation was observed between thermal neutron fluence and spark counts in the range 106 to 107 n.cm-2. A method of producing the single crystal converter is also described.
Soft Errors in Dynamic Random Access Memories - A Basis for Dosimetry
Authors: Haque A.K.M.M. , Yates J. , Stevens D.
Published: February 2017

The soft error rates of a number of 64k and 256k dRAMs from several manufacturers have been measured, employing a MC 68000 microprocessor. For this 'accelerated test' procedure, a 37 kBq (1 µCi) 241Am alpha emitting source was used. Both 64k and 256k devices exhibited widely differing error rates. It was generally observed that the spread of errors over a particular device/manufacturer was much smaller than the differences between device families and manufacturers. Bit line errors formed a significant part of the total for 64k dRAMs, whereas in 256k dRAMs cell errors dominated; the latter also showed an enhanced sensitivity to integrated dose leading to total failure, and a time-dependent recovery. Although several theoretical models explain soft error mechanisms and predict responses which are compatible with our experimental results, it is considered that microdosimetric and track structure methods should be applied to the problem for its better appreciation. Finally, attention is drawn to the need for further studies of dRAMs, with a view to their use as digital dosemeters.
A Routine ESR Technique for Dating Calcite Speleothems
Authors: Smith B.W. , Smart P.L. , Symons M.C.R.
Published: February 2017

The electron spin resonance (ESR) methods employed for measuring the dose accumulated by calcite since its deposition (the equivalent dose) have varied enormously from laboratory to laboratory. Following a detailed study of the stability and dose response of the ESR signals present in calcite, we previously reported that the signal at g=2.0005 (±0.0003) is the only one suitable for dating the last million years. The measurement of this signal requires great care as there is often significant interference from a very sharp signal at g=2.0001 (±0.0002) produced by grinding, and a short-lived radiation sensitive signal at g=2.0020 (±0.0003) which has previously not been recognised. Annealing techniques have been developed to remove interference from the latter and check for instabilities in the g=2.0005 signal which appear to be due to re-crystalisation of the calcite. A routine experimental procedure is described which in our experience produces reliable equivalent doses, and the advantages of the ESR technique are discussed.