bluuebunny/crossref_metadata_2025 huggingface dataset:
On the Use of TLD for Gamma Ray Dosimetry Evaluation in Mixed Fast Neutron and Gamma Ray Fields
Authors: Wang T-K.
Published: February 2017

Some assessments are provided on the use of thermoluminescence dosemeters (TLDs) for ? ray dosimetry evaluation in mixed (fast neutron-? ray) radiation fields. Dosimetry measurements and calculations were performed in three different experimental arrangements driven by 252Cf sources. Measurements were made with TLD-200, TLD-400 and TLD-700. Various corrections including the TLD neutron sensitivities and the general cavity theory f factors were applied to the measurements. Calculations were performed using diffusion code 2DB and discrete ordinate transport codes ANISN and DOT. Good agreement was found between TLD-200, TLD-400 and TLD-700 results. Generic deviations were found between calculated and measured results. Analyses showed that, due to the inaccuracies in standard computational schemes, calculations underestimate the measured results.
A New Development of Dyed ECE Tracks for Radiation Dosimetry
Authors: Sohrabi M. , Sadeghi Bajd S.
Published: February 2017

In a new development, high contrast red dyed ECE recoil tracks in polycarbonate and, partially, in CR39, have been successfully achieved at AEOI for radiation dosimetry. The principle incentive has been the provision of high contrast photon absorbing large dyed tracks on an unaffected bulk material for UV and/or IR spectrophotometry. The method consists of: (a) exposing the polymer to charged particles or neutrons, (b) ECE of tracks, (c) acid sensitisation, and (d) dyeing with a suitable dye. By investigation of the type, concentration, duration and temperature of acid and dye, optimised values of 20% by weight acrylic acid at 75 oC for 3.5 h for sensitisation and 3% by weight eosin bluish at 95 oC for 4 h dyeing provided nearly 100% dyeing efficiency. The optimisation results are also presented and discussed.
The Effect of the Registration Temperature on the Response of CR-39 to Alpha Particles and Fission Fragments
Authors: Durrani S.A. , Karamdoust N.A. , Al-Khalifa I.J.M.
Published: February 2017

The paper reports an investigation into the effect of track registration temperature on the track etching characteristics of CR-39 polymeric detectors exposed to a particles and fission fragments from a thin 252Cf source. The plastic detector was maintained at temperatures ranging from 77 K to 373 K during irradiation. It was observed that the overall track etching rate VT for a particles in CR-39 is influenced by registration temperature in a complex way. The value of the bulk etch rate VB, as measured from fission-fragment diameters, however, remained constant over the entire irradiation temperature range.
Thermoluminescence Dosimetry of Beta Radiation on the Basis of Several TL Detectors of Usual Thickness
Authors: Gotlib V.I. , Grebenschicov V.L. , Kantorovich L.N. , Nemiro E.A.
Published: February 2017

Detailed analysis of the thermoluminescence (TL) dosimetry method for ß radiation has been performed based on determination of the correction factor for energy dependence using the ratio J12 of TL responses of two detectors with different thickness (H1 < H2). It has been found that the optimum PVC filter thickness on the thick detector enhancing the resolution of the method is equal to 0.005-0.010 cm. It has been shown that the angular distribution of ß radiation causes a negligible error in the determination of the correction factor.
Mixed Field Personnel Dosimetry Using a Nearly Tissue-Equivalent Multi-Element Thermoluminescence Dosemeter
Authors: Moscovitch M. , Velbeck K.J. , Bencke G.M.
Published: February 2017

The method of response interpretation for determining dose equivalents of a new multi-element thermoluminescence dosemeter in mixed photon-beta and photon-neutron fields is described. The four TL chips are LiF:Mg,Ti, each covered by its own unique filter. Experiments to determine the response of the dosemeter and to test the dose calibration algorithm were performed according to the standard established by the US Department of Energy Laboratory Accreditation Program (DOELAP). It has been shown that the dosemeter response can be used to identify the mixture type. The accuracy of the system has been proven in blind testing to be well within DOELAP tolerance limits in all test categories.
Performance Analysis of the TNO TLD Individual Monitoring Service
Authors: van Dijk J.W.E. , Julius H.W.
Published: February 2017

The purpose of this study was to analyse the performance and to establish the lowest detectable, occupational dose (LDOD) of the TNO TL dosemeter, in use for large scale routine individual monitoring since 1983. The TNO individual monitoring service uses three TLD reader systems and over 45000 TL dosemeters, designed to measure Hs(0.07) and Hp(10). Each reader system is normalised daily and each individual dosemeter is calibrated every ten readout cycles. The performance of the service is monitored by a double blind experimental set-up. A series of 10 routine dosemeters is issued every fortnight, mailed, exposed by staff not involved in the monitoring service, sent back and evaluated. The conclusion of this study is that the lowest detectable occupational dose is less than 0.04 mSv and that the integrated dose at the level of the annual dose limit is measured within 2%.
TL Dosimetry Using Bricks and Tiles for Measurement of Transient Gamma Ray Dose in Inhabited Areas
Authors: Haskell E.H. , Bailiff I.K.
Published: February 2017

The pre-dose TL technique was used to measure accrued dose in three brick samples removed from houses in a community which was formerly the site of a uranium mill. The samples were analysed using a variety of pre-dose methods, including thermal activation characteristic (both multiple activation and additive dose), the multiple activation method, modified additive dose method, modified additive dose with anneal, and additive dose method. Results reveal no significant differences between the two laboratories or between methods with the exception of the multiple activation method, which showed signs of non-linearity by one method of analysis. The additive dose method displayed the highest level of uncertainty and produced the highest dose estimates in two of the three samples. Changes in degree of sensitisation resulting from heating effects and shifts in thermal activation characteristics are examined in detail. None of the samples revealed accrued doses which were significantly higher than background dose measurements.
Miniaturised Dose Measuring System Based on an Opto-Fibre Coupled Scintillation Probe
Authors: Low H.G. , Bonatz W. , Binder W.
Published: February 2017

The design of a miniature sensor system for point measurements of dose and dose rate of ionising radiation in various phantom materials and in tissue is described. A scintillation probe was used as a sensor of maximum dimensions of 1 x 1 x 1 mm3 which was opto-fibre coupled to the measuring instrument and an analysing device. Various materials were tested as probes. Measurements were made at different qualities of ionising radiation (10 to 200 kV, 60Co, 6 MV, 42 MV and electrons of 5 to 40 MeV). Various opto-fibres were tested to investigate the optimal signal transfer.
The Use of LiF for Dosimetry in the Megagray Range and at Elevated Irradiation Temperatures
Authors: Waibel A. , Göksu H.Y. , Regulla D.F.
Published: February 2017

For the study of radiation effects in rock salt caused by highly radioactive waste in potential repository sites, it is essential that dosimetry can be carried out at high irradiation temperatures. Radiation induced colour centres in LiF crystals are shown to be appropriate for the assessment of gamma doses up to at least 50 MGy at irradiation temperatures up to 250 oC. The irradiations were performed at 50 oC, 100 oC, 150 oC, 200 oC and 250 oC under calibration conditions in a gamma cell irradiator using a specially designed oven. The effect of the irradiation temperature on the dose response and shape of optical spectra of LiF is investigated. A method is described that allows for the estimation of the irradiation temperature. The experiments are designed to be used at the HAW project in the Asse salt mine, Braunschweig, FRG.
Modern Automatic Readout Systems for Phosphate Glass Dosemeters Using UV Laser Excitation
Authors: Burgkhardt B. , Piesch E. , Vilgis M. , Ishidoya T. , Ikegami T.
Published: February 2017

The new automatic readout systems FGD-10 and FGD-20 for flat glass dosemeters using pulsed UV laser excitation are applicable in the photon energy range 15 keV - 1.3 MeV and in the dose range above 0.03 mSv. Using the automatic readout mode for vertical and horizontal scanning of the glass, both systems allow interpretation of radiation conditions in personnel monitoring. The fully automatic systems make use of a dosemeter encapsulation unlocked and opened automatically within the reader. Separate code numbers of the capsule and the glass card are registered. The reader FGD-10 (FGD-20) is capable of continuously reading out 500 dosemeters (20 dosemeters) in magazines within a readout time of 20 s (10s) per dosemeter. FGD-10 exchanges automatically high-dosed by annealed glass cards and allows data handling for 50,000 dosemeters. The microprocessor controlled evaluation technique provides intrinsic subtraction of pre-dose during readout, automatic calibration using the same dosemeter during the monitoring period, simultaneous indication of different dose quantities and interpretation of radiation quality and incidence. The fully automatic PLD systems optimised in the readout procedure and prototype-tested are expected to be reliable dosimetry systems for application in individual and environmental monitoring.
Something Old, Something New, Something Basic
Authors: Attix F.H.
Published: February 2017

'Something Old' is a photograph of the organisers of the first Conference on Luminescence Dosimetry held at Stanford University in 1965. 'Something New' is the scintillation dosimetry probe developed at the University of Wisconsin, and now available commercially for in-phantom, in vivo and stereotaxic beam applications. 'Something Basic' is an analysis of the problem of determining the average dose deposited by an electron beam in a flat dosemeter of foil, comparing various analytical approaches with Monte Carlo results.
Isothermal Decay of Glow Peaks in LiF:Mg,Cu,P
Authors: Delgado A. , Gómez Ros J.M. , Furetta C. , Bacci C.
Published: February 2017

Isothermal decay (ID) experimental data for peaks 2, 3 and 4 of LiF:Mg,Cu,P (China) are presented. For every peak the ID has been measured at different temperatures, so that the evolution of life-time with temperature has also been determined. Peaks 2 and 4 present a very simple exponential decay typical of first order kinetic processes. Peak 3 decay is more complex due to the unavoidable contribution of the intense peak 4. After the subtraction of this contribution, peak 3 decay is exponential indicating first order kinetics for this peak too. From the good linear dependence of lnt on l/T, values for the activation energy and the frequency factor for all the peaks studied have been obtained. Peak 4 parameters have shown to be very critically dependent on the cooling rate in the annealing procedure. The LiF:Mg,Cu,P decay features are discussed with regard to those of LiF:Ti,Mg (TLD-100).
Elimination of the High Temperature Glow Peak in LiF:Cu,Mg,P
Authors: Horowitz A. , Horowitz Y.S.
Published: February 2017

Previous studies have reported a significant residual signal in LiF:Cu,Mg,P (GR-200) which arises from a peak at 270 oC with an intensity of 7-50% relative to the main dosimetry peak. A method has been found to prepare LiF:Cu,Mg,P in two forms; one with a TL sensitivity 30-40 times greater than TLD-100 but with a residual signal of only 2-3% following 240 oC for 10 s readout, the other, even more optimised material (SSD-NR), with a sensitivity 15-20 times that of TLD-100 but with the 270 oC peak almost totally eliminated, leading to a residual signal of 0.25-0.5%.
Photoacoustic Spectroscopy on Differently Doped LiF Samples
Authors: Kelemen A.
Published: February 2017

Dosimetric materials used in practice generally exist in the form of powder or chips which are unsuitable for conventional optical absorption spectroscopy (OAS) measurements. Photoacoustic spectroscopy (PAS) gives information about absorption properties of opaque and powdered samples in a wide range of optical absorbance. Photoacoustic spectra of differently doped LiF samples (LiF:Cu,Mg,P from Beijing, LiF doped with Ti and different amounts of Mg, and TLD-100) were recorded at various high (>100 kGy) 60Co gamma doses in the 220-600 nm wavelength region. PA and OA spectra were compared and similarities as well as differences were found. Dependence of spectra on the Mg content and on the irradiation dose is discussed. Evaluation of the PA spectrum of LiF:Mg,Cu,P revealed no extra peaks compared with LiF:Mg,Ti.
Preparation and Characteristics of LiF:Mg,Cu,P Thermoluminescent Material
Authors: Zha Z. , Wang S. , Shen W. , Zhu J. , Cai (INVITED) G.
Published: February 2017

The preparation and characteristics of LiF:Mg,Cu,P TL material are described and recent improvements are also dealt with. The reproducibility, glow curve structure and other properties of LiF:Mg,Cu,P are dependent not only on the dopant concentration and crystallisation procedure but also on the thermal treatment programme, i.e. the temperature and the time of annealing. Usually the sensitivity (light integration) of LiF:Mg,Cu,P is influenced by the high temperature peak (250 oC). The combined annealing method (270 oC/240 oC double temperatures) can significantly reduce the higher temperature peak and therefore the TL repeatability is improved. Once the optimised preparation procedure and thermal treatment are chosen, the TL sensitivity is stable with re-use. The experimental results show that LiF:Mg,Cu,P has a promising potential in routine applications, (e.g. personal and environmental monitoring for gamma radiation) especially for ultra-low dose monitoring.
UV Emission in the TL Peaks of CaSO4:Dy; Origin and Application to High Temperature Dosimetry
Authors: Goyer D. , Lapraz D. , Iacconi P. , Portal G. , Barthe J. , Prévost H. , Gasiot J.
Published: February 2017

In order to understand better the origin of the TL UV emission in CaSO4:Dy, several factors have been studied such as the influence of the pre-annealing temperature, the Dy concentration and the effect of the dose, on two compounds, one commercially available and the other synthesised in the laboratory. A UV induced TL phototransfer is observed between 20 and 400 oC for the former. Application to high temperature dosimetry of CaSO4:Dy is discussed.
Thermoluminescence of Hydroxyapatite Doped with Copper
Authors: Fukuda Y. , Ohtaki H. , Tomita A. , Takeuchi N.
Published: February 2017

Thermoluminescence (TL) of hydroxyapatite, Ca5(PO4)3OH (abbreviated as OHAP) has been investigated by several authors, because this material is a main constituent of human bones. The samples showed two main TL peaks at about 110 and 150 oC by heating them at a rate of 20 oC.min-1 after X irradiation at RT. In order to use the TL glow peaks for dosimetry, it is desirable to intensify the 150 oC peak by the addition of activators, if possible, because the 110 oC peak is unstable under storage at RT after the irradiation. It was found that the OHAP doped with 0.03 wt% CuO showed about five times more intense a TL peak at 150 oC than the undoped one for an X irradiation of 0.465 C.kg-1, while the peak at about 110 oC decreased slightly. It was noted that a new TL peak was observed at 340 oC in OHAP:CuO. The 340 oC TL peak may also be suitable for the purpose.
Ultraviolet Response of CaF2:Tm Phosphor with Double Temperature Treatment
Authors: Hsu P.-C. , Wang C.-D. , Weng P.-S. , Li S.-H.
Published: February 2017

The effect of the pre-irradiation double temperature treatment on the CaF2:Tm phosphor was studied. The high intrinsic thermoluminescent (TL) sensitivity to ultraviolet radiation after high temperature treatment can be retained and stabilised by following with medium temperature treatment. The TL properties were investigated by analysing the TL output and glow curve. The experimental results indicate that (1) the intrinsic TL sensitivity to UV can be stabilised for a 300 oC medium temperature treatment after a 1 hour 850 oC high temperature treatment, (2) the linear response ranges are 2.0 to 103J.m-2, 7.0 to 7 x 103J.m-2 and 30 to 3.5 x 103J.m-2 with respect to 253.7, 302 and 365 nm UV, respectively, and (3) there is no TL response to visible light. However, the TL output is wavelength dependent, which limits the application of this phosphor as a personal UV dosemeter.
Optical Absorption and Thermoluminescence Studies in CaF2:Tm Crystals Irradiated at Room Temperature
Authors: Lakshmanan A.R. , Tiwari S.S.
Published: February 2017

Optical absorption (OA), thermoluminescence (TL), phototransfer and photobleaching studies on CaF2:Tm single crystals irradiated with gamma rays at 25 oC indicate that the TL peaks at 160 oC, 180 oC and 480 oC are due to hole activation (giving rise to OA bands near 310 nm) and subsequent recombination with Tm2+ (giving rise to OA bands near 400 and 600 nm) resulting in Tm3+ emission. However, the major TL peak at 280 oC could not be associated with any OA band. Results indicate that this peak could arise because of electron activation, recombination with hole and subsequent resonant energy transfer to Tm3+ ions.
Type Testing of Thin Layer Hot Pressed TLDs - Energy and Angular Response for Photons
Authors: Vermaercke P. , Lesz J. , Maes L. , Loos M.
Published: February 2017

The measurement of the ICRU quantities, the individual dose equivalent penetrating, Hp(d) and superficial, Hs(d) should be performed at well specified depths. This requirement leads to the use of thin layer detectors. As is known from the literature, the filter/detector configuration becomes simple if LiF based thermoluminescent detectors are used. Long-term stable, fully annealable at 400 oC and LiF-based thin layer TLDs, manufactured by ENDOS GmbH appear suitable for modern radiation protection dosimetry. The filter/thin layer detector configuration within the dosemeter badge has been optimised with respect to the ICRU requirements. Experimental data are reported on energy and angular response to photons for a few carefully selected filter combinations. A dosemeter badge enabling routine Hs(0.07) and Hp(10) measurements is presented.
A System for Extremity Monitoring
Authors: Tawil R.A. , Velbeck K.J. , Rotunda J.E. , Gooley R. , Moscovitch M. , Wu C.F.
Published: February 2017

The system presented consists of a reader, single and filtered multi-element configuration dosemeters, and dose algorithm. The reader is a non-contact linear gas heating medium capacity unit interfaced to an application software package that evaluates and manages generated data. The dosemeters are fabricated from elements that are 100 mg.cm-2, 40 mg.cm-2 and 20 mg.cm-2, the multi-element configurations are filtered by copper and tin. Batch uniformity, repeatability, reproducibility, detection level threshold, and angular response for these dosemeters are studied and presented. Response as a function of beta energies relative to 137Cs as well as energy discrimination capabilities are reported. The dose calculation algorithm that was developed for the various different detector configurations is presented and the accuracy of its performance in pure and mixed fields has been determined and compared with published and proposed HPSSC-ANSI Standards.
A New Individual Extremity TL Dosimetry System
Authors: Brand H.N. , Regulla D.
Published: February 2017

The industrial prototype of an individual extremity thermoluminescence (TL) dosimetry system is presented which is based on a GSF patent and has been developed by Physikalisch-Technische Werkstatten, Freiburg. The system consists of a flexible strip type TL dosemeter also serving as a ring dosemeter, and a PC controlled readout equipment. The dosemeter carries a permanent identification code and is prepared for one use. Performance tests have revealed system compliance with the dosimetric requirements of the German Standard DIN 6816.
TLD System with a Stacked Dosemeter Configuration
Authors: Holzapfel G. , Lesz J. , Sujak-Lesz. K.
Published: February 2017

A new design of TL dosemeter, developed by ENDOS, is presented. It contains two stacked individually coded, detectors of the thin LiF:Mg,Ti layer type. Preliminary measurements indicate flat responses with respect to both photon energy and angle of incidence. This holds for both skin and depth dose as recommended by ICRU.
Exposure to Neutron Radiation Commercial Flights
Authors: Apfel R.E.
Published: February 2017

Neutron radiation has been measured in several commercial flights at altitudes ranging from 8.5 to 11.0 km, and for flight duration at altitudes ranging from 1.25 to 6.5 hours. The measurement technique employed involves superheated drop compositions in a pen-like configuration (called a Neutrometer(). When neutrons interact with a superheated drop, the drop vaporises, immediately producing a 1 mm diameter bubble. The particular superheated drop composition used in the neutrometer has been shown to have a nearly dose equivalent response when calibrated with monoenergetic neutrons, and to have no sensitivity to gamma rays below 6 MeV. Bubbles produced as a result of the neutron radiation array themselves in a single line, and are easily counted. The sensitivity ranges from five to seven bubbles per 10 µSv of neutron radiation. The average rate of exposure for the several flights was approximately 0.8 to 0.9 µSv.h-1.
Thermoluminescence Response of Heavy Concrete Used in the Shielding of the CERN 600 MeV Synchrocyclotron
Authors: Kitis G. , Charalambous S. , Tuyn J.W.N.
Published: February 2017

Heavy, barytes loaded, concrete is commonly used as shielding material around high energy particle accelerators. Samples of such material were taken from the shielding wall of the CERN 600 MeV synchrocyclotron to study its thermoluminescence response and subsequently to estimate the correct order of magnitude of the dose received by the wall during the 34 years of its operation. The method shown in this paper is of interest to reconstruct the dose distribution inside, e.g. accelerator areas, for the purpose of material damage studies.
Measurement of the Stimulation Spectrum (1.2-1.7 eV) for a Specimen of Potassium Feldspar Using a Tunable Solid State Laser
Authors: Bailiff I.K.
Published: February 2017

The dating of sediments by infrared stimulated luminescence (IRSL) has attracted considerable interest, particularly in view of the simple means by which it can be measured. However, little is known of either the physical mechanisms which are associated with IRSL or the characteristics to be expected when using the technique to evaluate accrued dose in feldspar-bearing samples. The IRSL stimulation spectrum has been measured for a specimen of orthoclase which shows a single broad band at room temperature with a maximum at 1.46 eV and FWHM, 0.17 eV. The form of the stimulation spectrum was found to be substantially unchanged under various measurement conditions including: (a) elevated sample temperature during stimulation and (b) detection of IRSL in the wavelength regions of either of the two major emission bands.
Models of the g = 2.0006 ESR Signal Growth Curve in Carbonates
Authors: Cetin O. , Wieser A. , Walther R. , Özer A.M. , Fill U. , Regulla D.F.
Published: February 2017

Several mathematical equations for describing the growth curve of modern and fossil carbonate samples are discussed. The best approximation for the dose response of the g = 2.0006 ESR dating signal in aragonitic coral and shell samples was found by a combination of three single exponential saturation functions. Also the isothermal decay curves of the ESR signal proved to be best fitted by the combination of three first order decay functions. The lifetimes of the three components were obtained from an Arrhenius plot. For different species of mollusc shells the lifetime of the less stable component was found in the range 30-90 ka at 2 oC. It can be removed by heating the samples at 180 oC for a period of 2 h.
Electron and Proton Dosimetry with Custom-Developed Radiochromic Dye Films
Authors: Uribe R.M. , Vargas-Aburto C. , McLaughlin W.L. , Walker M.L. , Dick C.E.
Published: February 2017

The systematic study and identification of the mechanisms responsible for changes occurring in radiochromic dye films (RDFs) as a result of exposure to ionising radiation, requires the possibility of varying a number of parameters during their fabrication. A series of RDFs were developed with thicknesses in the range of 15 to 60 µm. The amount of dye precursor and stabilisers was varied in a systematic way. A series of unexposed films was irradiated with 1 MeV electrons and 10 MeV protons. Optical characterisation of the films was performed. Irradiations were carried out in the dose range from 0 to 440 kGy. The fabrication techniques, the irradiation procedures, and the optical characterisation of the films are described. Conclusions are presented regarding the useful dose range for the RDFs, their sensitivity to different types of radiation, and a comparison is made with other similar film dosemeters used in the materials processing industry.
Calculation of Heavy Ion Inactivation Probabilities Based on Track Structure, X Ray Sensitivity and Target Size
Authors: Scholz M. , Kraft G.
Published: February 2017

A track structure model for the calculation of inactivation probabilities of heavy ions has been developed, which is based on measurable quantities only. The model describes the following inactivation properties of heavy ion radiation: (1) the transition from shouldered to exponential survival curves, depending on the atomic number, energy and LET of the particle; (2) the LET dependence of inactivation cross sections s, including the supralinear increase for low LET particles, the plateau region between 200 and 1000 keV.µm-1 and the s LET hooks for higher LET values; (3) differences in the shape of the s LET hooks for different biological objects; (4) the shift of RBE maxima from 30 to 300 keV.µm-1 with increasing atomic number; (5) the exchanged efficiency of heavy ions in the case of mixed radiation fields (X rays combined with heavy ion irradiation).
Biological Consequences of Non-Homogeneous Energy Deposition by Ionising Radiation
Authors: Ward J.F. , Jones G.D.D. , Milligan (INVITED) J.R.
Published: February 2017

The chemically reactive species produced by ionising radiation react within 2-3 nm of their site of origin causing locally multiply damaged sites (LMDS) (such as double strand breaks (DSBs)) on cellular DNA. As the LET of the radiation increases the number of individual damages in a LMDS increase. Since initial yields of DSBs show little dependence on LET, the higher RBE associated with higher LET radiation must be associated with the cell's ability to handle the damage - the nature of the damage is important. DSB repair studies do not assess the repair fidelity, this may be assessed at the molecular level by studies of mutation types produced: correct DSB rejoining, but with an error in base sequence would show as a point mutation in an exon. Degradation at DSB termini, non-homologous recombinational repair or misrejoining of a DSB with the wrong DSB terminus would form a deletion.
Transformation Frequency of Gamma-Irradiated Plasmid DNA and the Enzymatic Double Strand Break Formation by Incubation in a Protein Extract of Escherichia Coli
Authors: Schulte-Frohlinde D. , Mark F. , Ventur Y.
Published: February 2017

It was found that incubation of ?-irradiated or DNaseI-treated plasmid DNA in a protein extract of Escherichia coli leads to enzyme-induced formation of double strand breaks (dsb) in competition with repair of precursors of these dsb. A survival curve of the plasmid DNA (as determined by transformation of E. coli was calculated on the basis of enzyme-induced dsb as well as those produced by irradiation assuming that they are lethal. The calculated D0 value was the same as that measured directly by transformation of irradiated plasmid DNA. Two models are presented that fit the experimental survival data as a function of dose. One is based on damage formation in the plasmid DNA including enzymatic conversion of single strand damage into dsb (U-model), the other is an enzymatic repair saturation model based on Michaelis-Menten kinetics. A closer inspection of the models shows that the U-model does not incorporate the observed repair saturation and the repair saturation model does not incorporate the observed higher order formation of dsb. A more valid model may be developed by combining the two models.
Nuclear and Chromatin Structures and Their Influence on the Radiosensitivity of DNA
Authors: Oleinick N.L. , Chiu (INVITED) S.-M.
Published: February 2017

Among the factors contributing to the distribution of DNA damage within irradiated mammalian cell nuclei are the interactions of DNA with nuclear proteins and the formation of multi-molecular chromatin structures. Studies on the manipulation of chromatin structures of isolated nuclei are summarised. The majority of chromatin within the nucleus of living cells is tightly compacted into nucleosomal superhelices and other higher order structures which have a limited ability to be damaged by radiation. The treatment of isolated nuclei with hypotonic buffers causes a decondensation of these structures and markedly sensitises the DNA to radiation, while retaining the majority of the chromosomal proteins. On the other hand, treatment of nuclei with hypertonic buffers strips the DNA of specific classes of nuclear proteins, destroying chromatin structure, and this procedure also enhances the sensitivity of the DNA to radiation. The various expanded chromatin structures are models for the structure of the minor fraction of DNA which is decondensed in preparation for transcription or replication. The combined results indicate that the majority of nuclear DNA is protected by histones and other nuclear proteins from radiation damage, partially as a result of the limited accessibility of the condensed structures to hydroxyl radical and partially as a result of the scavenging of radicals by the proteins. In addition to these considerations, the elevated radiosensitivity of DNA associated with the nuclear matrix may result from the site specific generation of hydroxyl radical by matrix bound metal ions.
Microdosimetric Dosemeters for Individual Monitoring Based on Semiconductor Detectors
Authors: Schröder O. , Schmitz T. , Pierschel M.
Published: February 2017

The benefit of applying microdosimetric methods to practical radiation protection has been shown with regard to area monitoring. Tissue-equivalent proportional counters are used to measure distributions of energy deposition, which allows the simultaneous determination of absorbed dose and radiation quality in mixed photon and neutron fields. Semiconductor chips are an alternative to proportional counters as active individual dosemeters as they are small in size and very robust. They can be used as microdosimetric detectors for mixed field dosimetry since in memory chips and charged coupled devices (CCD), the radiation sensitive structures have thicknesses of the order of some micrometres. Measurements were performed in a collimated fast neutron beam with commercially available static random access memory (SRAM) chips. Additional tests were performed using a 241Am source. The charge collection capabilities of a modified CCD were studied with simulation calculations. The suitability of these two kinds of silicon semiconductor devices as microdosimetric detectors is discussed.
New Devices for Individual Neutron Dosimetry
Authors: Barthe J. , Bordy J.M. , Mourgues M. , Lahaye T. , Boutruche B. , Ségur P.
Published: February 2017

This paper deals with the design and fabrication of three new dosimetric sensors to be used in personal radiation monitoring. The first two sensors, double diode and streamer chamber, are based on the same particle detection principle, the last is a multicellular tissue-equivalent proportional counter. Each dosimetric sensor has a preferential range of applications. The double diode dosemeter, called DIAC, is the least sensitive, but can be reduced to the size of an 'electronic credit card' weighing a few 10s of grams. Two versions of the streamer chamber have been developed, the first corresponding to a personal device called DINE and the second to an ambient device called DANE. These two sensors are much more sensitive than the DIAC. The last sensor, studied in the SDOS laboratory, is a multicellular proportional counter called MC-TEPC. Giving both the dose and the dose equivalent quantities, it is more suitable for a good evaluation of the radiation risk but many problems due to gas aging have to be solved.
Analysis of Radon Mitigation Techniques Used in Existing US Houses
Authors: Henschel (INVITED) D.B.
Published: February 2017

This paper reviews the full range of techniques that have been installed in existing US houses for the purpose of reducing indoor radon concentrations resulting from soil gas entry. The review addresses the performance, installation and operating costs, applicability, mechanisms, advantages, and disadvantages of each radon mitigation technique. Active soil depressurisation (ASD) techniques are the measures most widely used by mitigation contractors. ASD techniques consistently and reliably provide the highest radon reductions, at costs often competitive with the less effective alternatives. The large majority of existing US houses having elevated radon can be effectively treated using ASD. Various other techniques can be used in houses where ASD is difficult or impractical to apply, or where lesser radon reductions are acceptable. However, these other techniques are always less effective, less reliable, or less well demonstrated than ADS.
Field Trials on the Effectiveness of Radon Protection Measures in New Dwellings
Authors: Woolliscroft M. , Scivyer C. , Parkins L.
Published: February 2017

The purpose of the field trials reported here was to verify the effectiveness of radon protection measures implemented under UK Building Regulations. Measurements were carried out in a total of 423 dwellings using etched track detectors. Some of the dwellings were protected, others were not. Four factors were considered likely to affect the annual average indoor radon level: (1) The radon level of the area. (2) The type of floor construction. (3) The presence or absence of a protective membrane in the floor construction. (4) Whether the dwelling was detached or attached to other dwellings. The radon level of the area is characterised by the proportion of existing houses in the area above the action level. The type of construction is generally in situ concrete floor or block and beam floor. Houses were situated on a total of 33 sites scattered all over Devon and Cornwall in the south west of England (an area of relatively high radon levels) offering a variety of both terrain and housing types. Statistical analysis showed that the effect of the membrane in reducing the radon level was significant at the 0.1% level. The effect of the floor construction, was however only significant at the 5% level. Neither the radon level of the area in which the dwelling was situated nor whether the dwelling was detached or attached had statistically significant effects on the radon level.
Reduction of the Radon Entry Rate from Building Materials by Industrial Surface Coatings
Authors: de Jong P. , van Dijk W.
Published: February 2017

The retaining effect of over 20 different surface coatings on the free 222Rn exhalation rate has been studied. Coatings that are normally applied for decoration of walls and ceilings in homes were found to be ineffective. Reductions of up to 75% were found for other coatings studied, when applied to all sides of the test walls. If the surface coating is applied to only one side of the wall, coatings on the basis of epoxy resin and polyurethane could reduce the exhalation rate by 95% according to model calculations.
Radon Risk Mapping - A Method of Predicting Problem Areas on Geological Grounds
Authors: Kullman F.
Published: February 2017

The Swedish stipulations of a maximum radon daughter level of 200 Bq.m3 for permanently inhabited buildings, and of 70 Bq.m-3 for buildings built later than 1981, has created a need to evaluate the radon risk caused by the ground. Radon risk mapping is done both on a regional scale and a detailed scale. When mapping, the ground is classified into high, normal and low risk areas. The classification work is started by an interpretation of all available geological material from the investigated area. This is followed by field investigations including radon measurements in possible risk areas, and control of radium content by gamma spectrometry in the typical rock types and soil types of the area. Results from MRM Konsult's radon measurements show a very large increase of high radon houses within high risk areas, classified according to the above model, if compared to randomly distributed measurements.
A Fast and Accurate Radon Measurement Tool for Remedial Actions in Buildings
Authors: Soavi R.
Published: February 2017

Continuous monitoring of radon concentration is an effective and fast method for assessing radon sources in buildings. For this purpose, fast response and absence of residual contribution from previous measurements is of primary importance to cut intervention time and cost in a remedial action. An instrument is described based on a scintillation cell. Counts from the detection assembly are processed by a microprocessor-based unit in order to compensate plateout and thus shorten the detector response step down to 15 min compared to the typical 3 h. A new treatment of the cell background, added to the algorithms, cancels the detector memory of previous measurements. The instrument has the ability to characterise both high and low activity environments in rapid sequence, even with a switch off/on operation in between, with almost no influence on the measure accuracy. A discussion of the computations and results from measurements is given.
Recent Models for TL Supralinearity
Authors: Horowitz (INVITED) Y.S.
Published: February 2017

The various models proposed to explain TL supralinearity, i.e., trap and luminescent centre creation, competition, statistical 'multi-hit' processes, correlated TC-LC and track interaction are reviewed. The track interaction model, consistent with dose dependent efficiency of luminescent recombination, and created to conceptually accommodate the dependence of supralinearity on ionisation density is the preferred candidate to explain TL supralinearity and is reviewed in depth along with recent quantitative application of track structure-track interaction theory to alpha particle TL dose response curves.
Electron Spin Resonance and Thermoluminescence in Calcium Oxide Crystals
Authors: Boas J.F.
Published: February 2017

Highly coloured crystals of CaO and CaO:Mg have been studied using thermoluminescence emission spectra and electron spin resonance. The undoped CaO crystals show an intense phosphorescence at around 620 nm at room temperature and this arises from a peak in the TL curve at around 330 K. The emission arises from the process: F+ + e ® F* ® F + h? and the electron arises from the thermally activated release of electrons from Mg+ ions as well as from other traps of an unknown nature. The Mg doped CaO crystals do not exhibit the intense phosphorescence and do not show a glow curve peak at around 330 K. Rather they exhibit a glow curve peak at around 180 K with a peak emission wavelength ca 690 nm. The electron transfer processes in these crystals appear to be more complex than those in undoped CaO.
The Use of Thin Layer Vacuum Deposited Films for Integrating Radiation Dosimetry by Exo-electron Emission
Authors: Brown L.D.
Published: February 2017

Thermally stimulated exo-electron emission is a surface effect which permits the preparation of thin integrating dosemeter elements with a sensitive layer a few nanometres thick. The dosemeters described in this paper were prepared by the evaporation of lithium fluoride onto thin polyimide sheets under vacuum. These are suitable for measurements under situations involving appreciable dose gradients such as charged particle dosimetry, interface dosimetry and some microdosimetry problems. Development of an appropriate reader and early evaluation of the resulting dosimetry system are also discussed.
A New Automatic TLD Reader for Personnel Monitoring
Authors: King C.W. , Tawil R.A. , Shrader E.F.
Published: February 2017

The Model 8000 System is a high throughput, automatic TLD reader for personnel monitoring. This menu driven system is capable of reading stacked cards or holders and generates up to 4 simultaneous glow curves from a multiple-element badge. It displays these curves in colour graphics, and transmits the data for further processing. Experimental results on randomness of the system 'zero', the overall precision and the response to beta rays and neutrons are presented. Multiple dosemeter elements, when combined with different filter media, make it possible to determine mixed field dose.
A Remote Fibre-Optic Microdosimetry Reader
Authors: Braunlich P. , Jones S.C. , Tetzlaff W.
Published: February 2017

A microdosemeter probe has been developed which permits remote in vivo and, if desired, in situ measurement. It is primarily intended for application in radiotherapy. Its basic features are a microdosemeter placed in the tip of a hypodermic needle. It is heated by a short (<500 ms) pulse from a 6 watt CO2 laser. The heating pulse is coupled into an approximately 1 m long flexible KRS-5 fibre of 0.5 mm diameter. This coupler is attached to the output port of the laser. The fibre penetrates the centre of a 45 o mirror of 25 mm focal length inside a hand held device and enters a thin walled quartz tube inserted in a hypodermic needle. Both the quartz tube and the fibre terminate in the tip of the needle about 2 mm in front of a small amount of thermoluminescence dosimetry (TLD) material. The thermoluminescence, emitted from the microdosemeter in the tip of the needle, is guided by the quartz tube to the mirror and deflected towards a miniature phototube for registration. The signal is digitised and processed with a transient digitiser and a microcomputer. Preliminary performance data are reported.
Progress in Lyoluminescence Dosimetry in Aberdeen
Authors: Ettinger K.V. , Miola U.J. , Hunter C. , Temperton D.H. , Dixon S.M. , Forrester (INVITED) A.R.
Published: February 2017

Secondary alkyl radicals have been postulated as participating in the Russell-Vassilev scheme of generation of light, in lyoluminescence (LL). Using the spin-trapping technique, the presence of these radicals has been confirmed in many LL phosphors. Low energy ß emitters incorporated in co-crystallised mannose and sucrose impart a dose to the matrix, in good agreement with the expected value when calibrated with soft X ray sources. Accuracy of a few per cent is attained using glutamine dosemeters in a series of mailed intercomparisons in the industrial radiation processing dose range, by use of a heat treatment at 114 oC for 5 hours. New LL phosphors, leucine and iso-leucine have similar hydrogen content to standard muscle and thus their neutron kerma are very close to those of ICRU muscle in the energy range from a few keV to 10 MeV. These phosphors are suitable for medical application particularly when used with sensitisers.
TSEE and TL from Physically Processed Surface of Dosemeter Material
Authors: Kawanishi M. , Kikuchi R. , Yamamoto T. , Kubozoe T. , Watanabe Y. , Okabe S. , Kawamoto (INVITED) T.
Published: February 2017

With the purpose of searching for a way to discriminate with a single dosemeter between the absorbed dose in the surface region identified by TSEE or TL and that of the bulk by TL of different spectrum, Cu+ implantation into Li2B4O7 glass ceramics and Ag+, Cu+ and Mg+ implantation into LiF single crystals was carried out. The effects of ion implantation on the TSEE and the TL glow curves have been measured and are discussed.
Energy Dependence of the TSEE for Monoenergetic Electrons
Authors: Wieters C.U. , Kriegseis W. , Petel M. , Portal G. , Scharmann A.
Published: February 2017

The dependence of the TSEE from BeO thin film dosemeters on the energy of incident monoenergetic electrons in the 200 keV to 1.2 MeV range has been investigated in view of beta dosimetry applications in radioprotection. The dose response of samples covered with 7 mg.cm-2 tissue-equivalent material is not influenced by energy variations in the range between 200 and 700 keV. The sensitivities for electrons and 60Co photons are nearly the same.
A Combination of TLD Albedo and Sulphur Activation Techniques for Fast Neutron Personnel Dosimetry
Authors: Tuyn J.W.N. , Lakshmanan A.R.
Published: February 2017

A combination of a TL albedo dosemeter system consisting of a 6LiF + 7LiF pair and a sulphur pellet has been studied for fast neutron personnel monitoring in high-energy accelerator environments.
Kilogray Dosimetry with CaSO4:Dy-Teflon TL Dosemeters
Authors: Fontaine J. , Distenfeld C.H.
Published: February 2017

Thermoluminescence dosemeters routinely used for electron, photon and neutron personnel dosimetry have been used to monitor exposures up to 2000 Gy (2 x 105 rad). The system, manufactured by Teledyne Isotopes, was used to answer certain shielding questions arising in the control rod drive room of the Big Rock Point Nuclear Power Station. The useful upper exposure limit of CaSO4:Dy-Teflon has been extended by a factor of 2 to 10 over values quoted in popular references.
The Role of Standardisation in Thermoluminescence Dosimetry
Authors: Busuoli G. , Goldfinch E.P.
Published: February 2017

The historical development of international standards for dosemeters and readers by the International Standards Organisation and International Electrotechnical Commission, respectively, is traced. The likely way ahead in the development of standards for thermoluminescence dosimetry systems is also discussed.
Fading Characteristics of LiF and Li2B4O7 TLD Systems Dependent on the Ambient Temperature, the Monitoring Period and the Interval Between Irradiation and Readout
Authors: Burgkhardt B. , Piesch E.
Published: February 2017

The change in response of oven-annealed Harshaw LiF:Mg,Ti and Studsvik Li2B4O7:Mn,Si detectors has been investigated as a function of storage periods of up to 100 days at ambient temperatures of -18 oC, 25 oC, 40 oC and 70 oC. Detectors have been irradiated before storage, after storage, and at different times within the storage period of 100 days. In environmental monitoring LiF generally enables determination of field fading correction factors if control dosemeters are used.
Simultaneous Determination of Dose and Elapsed Time in Accident Dosimetry Using Thermoluminescent Materials
Authors: Furetta C. , Tuyn J.W.N. , Louis F. , Azorin J. , Driscoll C.M.H.
Published: February 2017

Information about the time which has elapsed since an external radiation exposure is useful in determining the time of occurence of an abnormal exposure in personal and accident dosimetry. This information can be obtained from certain irradiated thermoluminescence dosemeters. A computational method based on decay rates of thermoluminescence glow peaks has been used to estimate a range of suitable values of trap lifetimes of low temperature glow peaks. This provides a basis for the selection of an appropriate thermoluminescent material to assess not only the absorbed dose from a radiation exposure but also the elapsed time. The results of experimental studies have been used to obtain additional information on decay rates as a function of energy, temperature, and absorbed dose.