Search

Ionising radiation has been used for over a century for peaceful purposes, revolutionising health care and promoting well-being through its application in industry, science, and medicine. For almost as long, the International Commission on Radiological Protection (ICRP) has promoted understanding of health and environmental risks of ionising radiation and developed a protection system that enables the safe use of ionising radiation in justified and beneficial practices, providing protection from all sources of radiation. However, we are concerned that a shortage of investment in training, education, research, and infrastructure seen in many sectors and countries may compromise society’s ability to properly manage radiation risks, leading to unjustified exposure to or unwarranted fear of radiation, impacting the physical, mental, and social well-being of our peoples. This could unduly limit the potential for research and development in new radiation technologies (healthcare, energy, and the environment) for beneficial purposes. ICRP therefore calls for action to strengthen expertise in radiological protection worldwide through: (1) National governments and funding agencies strengthening resources for radiological protection research allocated by governments and international organisations, (2) National research laboratories and other institutions launching and sustaining long-term research programmes, (3) Universities developing undergraduate and graduate university programmes and making students aware of job opportunities in radiation-related fields, (4) Using plain language when interacting with the public and decision makers about radiological protection, and (5) Fostering general awareness of proper uses of radiation and radiological protection through education and training of information multipliers. The draft call was discussed with international organisations in formal relations with ICRP in October 2022 at the European Radiation Protection Week in Estoril, Portugal, and the final call announced at the 6th International Symposium on the System of Radiological Protection of ICRP in November 2022 in Vancouver, Canada.

Incorporation of bone seeking alpha-emitting radionuclides such as 241Am are of special concern, due to the potential of alpha particles to damage the extremely radiation-sensitive bone marrow. In the case of an internal contamination with 241Am, direct in vivo measurements using Gamma-detectors are typically used to quantify the incorporated activity. Such detectors need to be calibrated with an anatomical phantom, for example of the skull, of known 241Am activity that reproduces the anatomy of the measured individual as closely as possible. Any difference in anatomy and material composition between phantom and individual will bias the estimation of the incorporated activity. Consequently, in this work the impact of the most important anatomical parameters on detection efficiency of one of the germanium detectors of the Helmholtz Center Munich (HMGU) partial body counter were systematically studied. For that a detailed model of the germanium detector was implemented in the Monte Carlo codes GEANT4 and MCNPX. To simulate the detector efficiency, various skull voxel phantoms were used. By changing the phantom dimensions and geometry the impact of parameters such as shape and size of the skull, thickness of tissue covering the skull bone, distribution of 241Am across the scull and within the skull bone matrix, on the detector efficiency was studied. Approaches to correct for these parameters were specifically developed for three physical skull phantoms for which Voxel phantoms were available: Case 102 USTUR phantom, Max-06 phantom, BfS phantom. Based on the impact of each parameter, correction factors for an ‘individual-specific’ calibration were calculated and applied to a real 241Am contamination case reported in 2014. It was found that the incorporated 241Am activity measured with the HMGU partial body counter was about twice as large as that estimated when using the BfS skull phantom without applying any correction factor for person-specific parameters. It is concluded that the approach developed in the present study should in the future be applied routinely for skull phantom measurements, because it allows for a considerably improved reconstruction of incorporated 241Am using partial body counters.

La Commission internationale de protection radiologique (CIPR) a initié un examen et une révision du système de radioprotection afin de mettre à jour les recommandations générales de 2007 dans la Publication 103 de la CIPR. Il s’agit du début d’un processus de plusieurs années qui nécessite une collaboration ouverte et transparente avec les organismes et les personnes du monde entier. Bien que le système soit robuste et efficace, il convient de l’adapter à l’évolution des connaissances scientifiques et de la société afin de demeurer adapté aux besoins. Le présent document vise à encourager les discussions sur les domaines du système qui pourraient bénéficier le plus d’un examen, et à engager des initiatives de collaboration. Le renforcement de la clarté et de la cohérence constitue une priorité. Plus le degré de compréhension du système est élevé, plus il est possible de l’appliquer efficacement, ce qui se traduit par une amélioration de la protection et une harmonisation accrue. De nombreux domaines pourraient faire l’objet d’un examen, notamment : la classification des effets, avec un accent particulier sur les réactions tissulaires ; la reformulation du détriment radiologique, qui pourrait inclure les maladies non cancéreuses ; la réévaluation de la relation entre le détriment et la dose efficace, et la possibilité de définir des détriments pour les hommes et les femmes et différentes classes d’âge ; la variation de la réponse individuelle à l’exposition aux rayonnements ; les effets héréditaires ; les effets et risques pour le biote non humain et les écosystèmes. Certains des concepts de base sont également examinés, notamment le cadre permettant de réunir la protection des personnes et de l’environnement, les améliorations progressives des principes fondamentaux de justification et d’optimisation, une approche plus large de la protection des personnes et la clarification des situations d’exposition introduites en 2007. En outre, la CIPR envisage de déterminer dans quels cas l’incorporation explicite des fondements éthiques dans le système présenterait un avantage, comment mieux refléter l’importance des échanges et de l’implication des parties prenantes, et de donner des conseils supplémentaires sur l’éducation et la formation. La CIPR invite à répondre à ces questions et à d’autres liées à l’examen du système de radioprotection.

Recent studies suggest that every year worldwide about a million patients might be exposed to doses of the order of 100 mGy of low-LET radiation, due to recurrent application of radioimaging procedures. This paper presents a synthesis of recent epidemiological evidence on radiation-related cancer risks from low-LET radiation doses of this magnitude. Evidence from pooled analyses and meta-analyses also involving epidemiological studies that, individually, do not find statistically significant radiation-related cancer risks is reviewed, and evidence from additional and more recent epidemiological studies of radiation exposures indicating excess cancer risks is also summarized. Cohorts discussed in the present paper include Japanese atomic bomb survivors, nuclear workers, patients exposed for medical purposes, and populations exposed environmentally to natural background radiation or radioactive contamination. Taken together, the overall evidence summarized here is based on studies including several million individuals, many of them followed-up for more than half a century. In summary, substantial evidence was found from epidemiological studies of exposed groups of humans that ionizing radiation causes cancer at acute and protracted doses above 100 mGy, and growing evidence for doses below 100 mGy. The significant radiation-related solid cancer risks observed at doses of several 100 mGy of protracted exposures (observed, for example, among nuclear workers) demonstrate that doses accumulated over many years at low dose rates do cause stochastic health effects. On this basis, it can be concluded that doses of the order of 100 mGy from recurrent application of medical imaging procedures involving ionizing radiation are of concern, from the viewpoint of radiological protection.

In this study, the Geant4 Monte Carlo toolkit was used to simulate energy spectra of neutrons from secondary cosmic radiation at mountain altitudes for the Environmental Research Station "Schneefernerhaus" at the Zugspitze mountain, Germany (2660 m a.s.l.) and for Sphinx astronomical observatory at the Jungfraujoch, Switzerland (3585 m a.s.l.). Simulations were performed with different intra-nuclear cascade models available in Geant4, and the results were compared with those of measurements that had been performed at both locations by means of an Extended-Range Bonner Sphere Spectrometer. Measurement conditions were quite different for both locations - at Schneefernerhaus the measurements had been performed on the flank of a hill in March 2018 with much snow, while at Jungfraujoch the measurements had been performed on top of a steep local hill in September 2018 with much less snow. Despite these differences, agreement between measurement and simulation was reasonable at both locations, especially at neutron energies greater than 20 MeV where the (unknown) hydrogen content of the environment did not influence the neutron fluence much (i.e., results from simulations were 6-22% lower than those from the measurements for the Schneefernerhaus, and were 22-29% lower for Jungfraujoch, depending on intra-nuclear model used in the simulations). The agreement was less favorable for lower energies, where environmental hydrogen (e.g., snow cover, soil moisture) is known to influence the shape of the neutron energy spectrum, because the real conditions of the snow accumulation close to the location of the measurements were not known and, therefore, a detailed description of the real hydrogen environment in the simulations was not possible. When the results simulated using different intra-nuclear cascade models were compared with each other, agreement was found within +/- 5%, +/- 15%, +/- 20%, and +/- 20%, for cascade, evaporation, epithermal and thermal neutrons, respectively. While the latter results are consistent with those of simulations and measurements at the CERN EU High-Energy Reference Field (CERF) facility published recently, a detailed sensitivity analysis of the influence of environmental hydrogen on neutron energy spectra is required before a final quantitative comparison of measurements and simulations can be made. This sensitivity analysis is presently under way. It is concluded that simulation of energy spectra of neutrons from secondary cosmic rays close to the atmosphere-lithosphere interface, validated by the spectrometer measurements, showed differences of less than 30%, for neutron energies greater than 20 MeV, whatever intra-nuclear cascade model was used in the simulations.

Since 2012, the European Radiation Dosimetry Group (EURADOS) has developed its Strategic Research Agenda (SRA), which contributes to the identification of future research needs in radiation dosimetry in Europe. Continued scientific developments in this field necessitate regular updates and, consequently, this paper summarises the latest revision of the SRA, with input regarding the state of the art and vision for the future contributed by EURADOS Working Groups and through a stakeholder workshop. Five visions define key issues in dosimetry research that are considered important over at least the next decade. They include scientific objectives and developments in (i) updated fundamental dose concepts and quantities, (ii) improved radiation risk estimates deduced from epidemiological cohorts, (iii) efficient dose assessment for radiological emergencies, (iv) integrated personalised dosimetry in medical applications and (v) improved radiation protection of workers and the public. This SRA will be used as a guideline for future activities of EURADOS Working Groups but can also be used as guidance for research in radiation dosimetry by the wider community. It will also be used as input for a general European research roadmap for radiation protection, following similar previous contributions to the European Joint Programme for the Integration of Radiation Protection Research, under the Horizon 2020 programme (CONCERT). The full version of the SRA is available as a EURADOS report (www.eurados.org).

Purpose: To simulate secondary neutron radiation fields that had been measured at different relative positions during phantom irradiation inside a scanning proton therapy gantry treatment room. Further, to identify origin, energy distribution, and angular emission of the secondary neutrons as a function of proton beam energy. Methods: The FLUKA Monte Carlo code was used to model the relevant parts of the treatment room in a scanned pencil beam proton therapy gantry including shielding walls, floor, major metallic gantry-components, patient table, and a homogeneous PMMA target. The proton beams were modeled based on experimental beam ranges in water and spot shapes in air. Neutron energy spectra were simulated at 0°, 45°, 90° and 135° relative to the beam axis at 2 m distance from isocenter for monoenergetic 11 × 11 cm2 fields from 200 MeV, 140 MeV, 75 MeV initial proton beams, as well as for 118 MeV protons with a 5 cm thick PMMA range shifter. The total neutron spectra were scored for these four positions and proton energies. FLUKA neutron spectra simulations were crosschecked with Geant4 simulations using initial proton beam properties from FLUKA-generated phase spaces. Additionally, the room-components generating secondary neutrons in the room and their contributions to the total spectrum were identified and quantified. Results: FLUKA and Geant4 simulated neutron spectra showed good general agreement with published measurements in the whole simulated neutron energy range of 10−10 to 103 MeV. As in previous studies, high-energy (E ≥ 19.6 MeV) neutrons from the phantom are most prevalent along 0°, while thermalized (1 meV ≤ E < 0.4 eV) and fast (100 keV ≤ E < 19.4 MeV) neutrons dominate the spectra in the lateral and backscatter direction. The iron of the large bending magnet and its counterweight mounted on the gantry were identified as the most determinant sources of secondary fast-neutrons, which have been lacking in simplified room simulations. Conclusions: The results helped disentangle the origin of secondary neutrons and their dominant contributions and were strengthened by the fact that a cross comparison was made using two independent Monte Carlo codes. The complexity of such room model can in future be limited using the result. They may further be generalized in that they can be used for an assessment of neutron fields, possibly even at facilities where detailed neutron measurements and simulations cannot be performed. They may also help to design future proton therapy facilities and to reduce unwanted radiation doses from secondary neutrons to patients.

Incorporation of bone seeking alpha-emitting radionuclides such as

The International Commission on Radiological Protection (ICRP) has embarked on a process to review and revise the current System of Radiological Protection (‘the System’). To stimulate discussion, the ICRP published two open-access articles: one on aspects of the System that might require review, and another on research that might improve the scientific foundation of the System. Building on these articles, the ICRP organized a Workshop on the Future of Radiological Protection as an opportunity to engage in the review and revision of the System. This digital workshop took place from 14 October–3 November 2021 and included 20 live-streamed and 43 on-demand presentations. Approximately 1500 individuals from 100 countries participated. Based on the subjects covered by the presentations, this summary is organized into four broad areas: the scientific basis, concepts and application of the System; and the role of the ICRP. Some of the key topics that emerged included the following: classification of radiation-induced effects; adverse outcome pathway methodologies; better understanding of the dose–response relationship; holistic and reasonable approaches to optimization of protection; radiological protection of the environment; ethical basis of the System; clarity, consistency and communication of the System; application of the System in medicine and application of the principles of justification and optimization of protection.

In neutron fields including neutron energies above 20 MeV a conventional neutron dosimeter is not suitable for measurements of neutron personal dose equivalent, Hp(10), over the whole energy range. Therefore, for such fields an electronic neutron dosimeter has been developed recently at Helmholtz Zentrum Munchen (HMGU). In general, neutron dose measurements performed with this dosimeter at neutron energies below 2 MeV show an accuracy of about 30% [1]. Here we report the use of this dosimeter at the CERN-EU high-energy Reference Field (CERF) facility in Geneva, Switzerland. At this facility the available neutron fields include neutrons with energies below, but also above 20 MeV. In the present paper, personal dose equivalent (Hp(10)) values obtained with the ELectronic neutron DOsimeter (ELDO) are compared to neutron personal dose equivalent (Hp(10)) values obtained with the HMGU extended-range Bonner Sphere Spectrometer, and to reference values from FLUKA Monte Carlo simulations provided by CERF. It is shown that for continuous neutron spectra as those at CERF behind concrete shielding or secondary neutrons from cosmic rays, the dosimeter results are satisfactory for radiation protection purposes. However, in neutron fields including neutrons above about 7 MeV, where the major neutron dose contribution is from neutrons between 10 keV and several MeV (like those at CERF behind iron shielding), the doses provided by ELDO might be too small and care must be taken in interpreting the results.

Recently, two independent electronic dosimeters for individual monitoring have been developed at the Helmholtz Center Munich, Germany, one for photons and one for neutrons. Calibration of these dosimeters was performed using mono-energetic neutrons (energy range: 144 keV–14.8 MeV) and photons (12 keV–1.3 MeV), and the resulting calibration curves were compared to Monte Carlo simulations using the GEANT4 tool kit. In the present paper, an integrated dosimeter prototype is described which combines both dosimeters and therefore allows measurement of total dose in mixed neutron/photon radiation fields. It is demonstrated that the neutron channel of the combined dosimeter is insensitive to photons, while the photon channel is insensitive to neutrons. The prototype was tested in the field of an Am-Be neutron source which also includes a photon component. When the Am-Be neutron source was shielded by 9 mm lead, the combined dosimeter indicated a dose rate of 122.6 ± 1.0 μSv/h from neutrons and 7.3 ± 0.1 μSv/h from photons. In contrast, when the Am-Be neutron source was not shielded by lead, the combined dosimeter indicated a dose rate of 125.8 ± 1.0 μSv/h from neutrons and 65.9 ± 0.1 μSv/h from photons indicating a significant contribution from photons to total dose. In a second experiment when the Am-Be neutron source was closer to the combined dosimeter and a 137Cs source was added, a neutron dose rate of 421 ± 20 μSv/h and a photon dose rate of 849 ± 6 μSv/h was obtained. It is concluded that this instrument can be used in mixed photon-neutron fields with doses and dose rates typical for radiation protection purposes.

The European Radiation Dosimetry Group (EURADOS) is a network of organizations and scientists promoting research and development in the dosimetry of ionizing radiation, contributing to harmonization in dosimetry practice across Europe, and offering education and training in areas relevant for dosimetry. As a registered non-profit association under German law, EURADOS is currently running eight active working groups (WGs): WG2 on “Harmonization of Individual Monitoring”, WG3 on “Environmental Dosimetry”, WG6 on “Computational Dosimetry”, WG7 on “Internal Dosimetry”, WG9 on “Dosimetry in Radiotherapy”, WG10 on “Retrospective Dosimetry”, WG11 on “Dosimetry in High-Energy Radiation Fields”, and WG12 on “Dosimetry in Medical Imaging”. This paper presents recent scientific results obtained within these working groups, and additionally highlights the role of EURADOS as an organization which contributes to the development of a systematic strategy of radiation protection research in Europe.

In the present paper Geant4 Monte Carlo simulations of the CERN-EU high-energy Reference Field (CERF) facility in Geneva, Switzerland, are presented. At this facility a neutron field with a broad energy distribution from thermal energies up to GeV is available. To validate the simulated neutron fluences, the CERF neutron energy distribution was also measured with an extended range Bonner Sphere Spectrometer. Both measurements and simulations are compared against the official CERF reference distributions that were calculated with the Monte Carlo code FLUKA. It turned out that the differences between the total neutron fluences simulated with Geant4 and those measured were less than 41%, depending on the measurement position. While the total fluences simulated with the Geant4 Binary INC model (QGSP_BIC_HP) and the corresponding FLUKA reference values were up to 41% lower than those measured, the total fluences simulated with the Geant4 Bertini INC model (QGSP_BERT_HP) overestimated (up to 27%) the experimental results. As compared to the measured ambient dose equivalent H*(10), similar differences were observed with H*(10) values higher by about 29% for the Geant4 Bertini INC simulations and lower by about 48% for the Geant4 Binary INC and FLUKA simulations.

In this study, we present proof of concept for an x-ray detector. The hybrid device consists of a synthetic single crystal diamond in mechanical contact with a piezoelectric lithium niobate surface acoustic wave (SAW) delay line. Upon x-ray irradiation, the diamond crystal experiences a change in conductivity, which, in turn, very sensitively influences the SAW transmission on the delay line. This change in SAW attenuation is directly used to monitor the x-ray beam intensity. The SAW attenuation shows a monotonic variation with dose rate D in the studied range between 100 and 1800 μGy/s. While the response time leaves room for further improvement, the SAW detection principle offers the unique possibility for wireless remote powering and sensing.

A new electronic radon/thoron monitor employing semiconductor detectors based on a passive diffusion chamber design has been recently developed at the Helmholtz Zentrum Munchen (HMGU). This device allows for acquisition of alpha particle energy spectra, in order to distinguish alpha particles originating from radon and radon progeny decays, as well as those originating from thoron and its progeny decays. A Monte-Carlo application is described which uses the Geant4 toolkit to simulate these alpha particle spectra. Reasonable agreement between measured and simulated spectra were obtained for both 220 Rn and 222 Rn , in the energy range between 1 and 10 MeV. Measured calibration factors could be reproduced by the simulation, given the uncertainties involved in the measurement and simulation. The simulated alpha particle spectra can now be used to interpret spectra measured in mixed radon/thoron atmospheres. The results agreed well with measurements performed in both radon and thoron gas environments. It is concluded that the developed simulation allows for an accurate prediction of calibration factors and alpha particle energy spectra.

International audience; Since the early 1980s, the European Radiation Dosimetry Group (EURADOS) has been maintaining a network of institutions interested in the dosimetry of ionising radiation. As of 2017, this network includes more than 70 institutions (research centres, dosimetry services, university institutes, etc.), and the EURADOS database lists more than 500 scientists who contribute to the EURADOS mission, which is to promote research and technical development in dosimetry and its implementation into practice, and to contribute to harmonisation of dosimetry in Europe and its conformance with international practices. The EURADOS working programme is organised into eight working groups dealing with environmental, computational, internal, and retrospective dosimetry; dosimetry in medical imaging; dosimetry in radiotherapy; dosimetry in high-energy radiation fields; and harmonisation of individual monitoring. Results are published as freely available EURADOS reports and in the peer-reviewed scientific literature. Moreover, EURADOS organises winter schools and training courses on various aspects relevant for radiation dosimetry, and formulates the strategic research needs in dosimetry important for Europe. This paper gives an overview on the most important EURADOS activities. More details can be found at www.eurados.org. © 2018, The International Society for Prosthetics and Orthotics.

The aim of the International Commission on Radiological Protection (ICRP) is to protect humans against cancer and other diseases and effects associated with exposure to ionising radiation, and also to protect the environment, without unduly limiting the beneficial use of ionising radiation. As of the second half of 2017, four committees are contributing to the overall mission of ICRP, including Committee 1 (Radiation Effects). The role of Committee 1 includes consideration of the risks and mechanisms of induction of cancer and heritable disease; discussion of the risks, severity, and mechanisms of induction of tissue/organ damage and developmental defects; and review of the effects of ionising radiation on non-human biota at population level. This paper gives an overview of the recent activities of Committee 1, and discusses the focus of its active task groups.

Detailed characterization and classification of precipitation is an important task in atmospheric research. Line scanning 2-D video disdrometer devices are well established for rain observations. The two orthogonal views taken of each hydrometeor passing the sensitive area of the instrument qualify these devices especially for detailed characterization of nonsymmetric solid hydrometeors. However, in case of solid precipitation, problems related to the matching algorithm have to be considered and the user must be aware of the limited spatial resolution when size and shape descriptors are analyzed. Clarifying the potential of 2-D video disdrometers in deriving size, velocity and shape parameters from single recorded pictures is the aim of this work. The need of implementing a matching algorithm suitable for mixed- and solid-phase precipitation is highlighted as an essential step in data evaluation. For this purpose simple reproducible experiments with solid steel spheres and irregularly shaped Styrofoam particles are conducted. Self-consistency of shape parameter measurements is tested in 38 cases of real snowfall. As a result, it was found that reliable size and shape characterization with a relative standard deviation of less than 5 % is only possible for particles larger than 1 mm. For particles between 0.5 and 1.0 mm the relative standard deviation can grow up to 22 % for the volume, 17 % for size parameters and 14 % for shape descriptors. Testing the adapted matching algorithm with a reproducible experiment with Styrofoam particles, a mismatch probability of less than 3 % was found. For shape parameter measurements in case of real solid-phase precipitation, the 2-DVD shows self-consistent behavior.

For complete assessment of inhalation doses of radon and its progeny inside the three main ancient Egyptian tombs in Saqqara, seasonal radon concentrations have been measured by using a new electronic device that allows for measurement of real-time-resolved radon concentrations. Measurements were complemented by very fast measurements of thoron concentrations, which turned out to be low. Based on these measurements, annual residence time inside these tombs and the newest International Commission on Radiological Protection-recommended radon dose conversion coefficients or seasonal effective doses were calculated. The results indicate that workers receive highest annual effective doses of up to 140 mSv, which exceeds the annual limit of 20 mSv, whereas lower values up to 15 mSv are received by guides. In contrast, much lower doses were obtained for one-time visitors of the investigated tombs. The obtained results are somewhat different but still consistent with those previously obtained by means of fixed passive dose meters at some of the investigated places. This indicates that reasonable estimates of the effective dose of radon can be also obtained from short-term radon measurements carried out only twice a year (summer and winter season). Increasing the ventilation, minimizing the working times, etc., are highly recommended to reduce the annual effective dose. (C) 2018 Korean Nuclear Society, Published by Elsevier Korea LLC.

MELODI is the European platform dedicated to low-dose radiation risk research. From 7 October through 10 October 2013 the Fifth MELODI Workshop took place in Brussels, Belgium. The workshop offered the opportunity to 221 unique participants originating from 22 countries worldwide to update their knowledge and discuss radiation research issues through 118 oral and 44 poster presentations. In addition, the MELODI 2013 workshop was reaching out to the broader radiation protection community, rather than only the low-dose community, with contributions from the fields of radioecology, emergency and recovery preparedness, and dosimetry. In this review, we summarise the major scientific conclusions of the workshop, which are important to keep the MELODI strategic research agenda up-to-date and which will serve to establish a joint radiation protection research roadmap for the future.

Bonner Spheres Spectrometry in its high-energy extended version is an established method to quantify neutrons at a wide energy range from several meV up to more than 1 GeV. In order to allow for quantitative measurements, the responses of the various spheres used in a Bonner Sphere Spectrometer (BSS) are usually simulated by Monte Carlo (MC) codes over the neutron energy range of interest. Because above 20 MeV experimental cross section data are scarce, intra-nuclear cascade (INC) and evaporation models are applied in these MC codes. It was suspected that this lack of data above 20 MeV may translate to differences in simulated BSS response functions depending on the MC code and nuclear models used, which in turn may add to the uncertainty involved in Bonner Sphere Spectrometry, in particular for neutron energies above 20 MeV. In order to investigate this issue in a systematic way, EURADOS (European Radiation Dosimetry Group) initiated an exercise where six groups having experience in neutron transport calculations with the MC codes (MCNP, MCNPX, FLUKA, PHITS, MARS, or GEANT4) calculated the responses of a bare 3 He proportional counter, a 3 He proportional counter embedded in the middle of a 9 inch polyethylene sphere, and a 3 He proportional counter centred in a 9 inch polyethylene sphere containing a lead shell, at neutron energies of 1, 10, 100, and 1000 MeV. In general, calculated responses agreed very well for neutron energies below 20 MeV, whatever MC code used. At higher energies, however, certain differences were observed among the different calculations, which may mainly be attributed to the application of different INC models and their parameters. It was found that up to 1 GeV most of the results ranged between calculations previously published that were obtained with MCNP/LAHET using the Bertini INC model and GEANT4 using the Binary and Bertini INC models. These results indicate that use of different MC codes and INC models for the calculation of BSS response functions may result in an uncertainty of unfolded neutron fluences above 20 MeV of about 20%.

Background and purpose: Systematic investigation of the energy and angular dependence of secondary neutron fluence energy distributions and ambient dose equivalents values (H*(10)) inside a pencil beam scanning proton therapy treatment room using a gantry. Materials and methods: Neutron fluence energy distributions were measured with an extended-range Bonner sphere spectrometer featuring 3 He proportional counters, at four positions at 0 degrees, 45 degrees, 90 degrees, and 135 degrees with respect to beam direction and at a distance of 2 m from the isocenter. The energy distribution of secondary neutrons was investigated for initial proton beam energies of 75 MeV, 140 MeV, and 200 MeV, respectively, using a 2D scanned irradiation field of 11 x 11 cm(2) delivered to a 30 x 30 x 30 cm(3) PMMA phantom. Additional measurements were performed at a proton energy of 118 MeV including a 5 cm range-shifter (PMMA), yielding a Bragg peak position similar to that of 75 MeV protons. Results: Ambient dose equivalent values from 0.3 mu Sv/Gy (75 MeV;90 degrees) to 24 mu Sv/Gy (200 MeV;0 degrees) were measured inside the treatment room at a distance of 2 m from the isocenter. H*(10) values were lower (by factors of up to 7.2 (at 45 degrees)) at 75 MeV compared to those at 118 MeV with the 5 cm range-shifter. At 0 degrees and 45 degrees, an evaporation peak was found in the measured neutron fluence energy distributions, at neutron energies around MeV, which contributes about 50% to total H*(10) values, for all investigated proton beam energies. Conclusions: This study showed a pronounced increase of secondary neutron H*(10) values inside the proton treatment room with increasing proton energy without beam modifiers. For example, in beam direction this increase was about a factor of 50 when protons of 75 MeV and 200 MeV were compared. The existence of a peak of secondary neutrons in the MeV region was demonstrated in beam direction (0 degrees). This peak is due to evaporation neutrons produced in the existing surrounding materials such as those used for the gantry. Therefore, any simulation of the secondary neutrons within a proton treatment room must take these materials into account. In addition, the results obtained here show that the use of a range-shifter increases the production of secondary neutrons inside the treatment room. Using a range-shifter, the higher neutron doses observed mainly result from the higher incident proton energy (118 MeV instead of 75 MeV when no range-shifter was used), due to higher neutron production cross-sections. (C) 2017 American Association of Physicists in Medicine

In 2007, a Bonner spheres spectrometer (BSS) was installed in Ny-Alesund, Spitsbergen, at about 79°N. The spectrometer allows continuous measurement of the spectral fluence rate distribution of secondary neutrons from cosmic radiation in absolute terms. In this way, the system complements a neutron monitor (NM) that was installed in 2005, in Barentsburg, Spitsbergen, at about 78°N. To compare the readings of both systems, the NM response functions to neutrons and protons were calculated by means of the GEANT4 code, in the energy range between 10 meV and 100 GeV, and between 40 MeV and 10 GeV, respectively, using different intra-nuclear cascade (INC) models at energies above 20 MeV. Sample spectral fluence distributions as measured by means of the BSS system for neutrons in November and December 2007 were used and folded with the calculated GEANT4 NM response. The resulting calculated NM count rates were then compared to those actually measured by the NM system and a reasonable agreement between 7% and 43% was obtained, depending on the nuclear models used in the GEANT4 calculations and the assumed 10 B enrichment of the NM counters used to detect the neutrons.

The neutron field at the FRM II neutron therapy was characterised by means of a Bonner sphere spectrometer. Inside the therapy room and the adjacent radiography room, gold foils were used in the center of the moderating polyethylene (PE) spheres of the spectrometer, to detect the moderated neutrons. The measured neutron spectra are dominated – as expected – by neutrons with an energy of about 1 MeV. The spectra were in quantitative agreement with those calculated by means of the MCNP code, by Breitkreutz and co-workers. Outside the therapy room, 3 He proportional counters were used to detect the neutrons moderated by the PE spheres of the spectrometer. Here, the spectra were much softer and included thermal neutrons as major component. Based on these neutron spectra, the neutron ambient dose equivalent rate H ˙ ∗ ( 10 ) was calculated. The resulting H ˙ ∗ ( 10 ) values were between 0.92 and 1.68 μSv/h, depending on the position outside the shielding. These values were in close agreement to the one measured by means of the AMIRA tissue-equivalent proportional counter. It is concluded that the neutron spectra at the neutron therapy facility at the new FRM II research reactor at Garching, Germany, are now well characterised.

United States Transuranium and Uranium Registries (USTUR) Case 0102 was the first whole-body donation to the USTUR (1979), of a worker affected by a substantial accidental 241Am intake(1). Half of this man’s skeleton, encased in tissue-quivalent plastic, provides a unique human ‘phantom’ for calibrating in vivo counting systems. In this case, the 241Am skeletal activity was measured 25 y after the intake. Approximately 82 % of the 241Am remaining in the body was found in the bones and teeth. The241Am activity concentration throughout the skeleton (in all types of bone) was fairly uniform(2). A protocol has been proposed by a group of in vivo laboratories from Europe [CIEMAT-Spain, IRSN-France and Helmholtz Zentrum Mu¨nchen (HMGU)-Germany] and Canada (HML) participating in this DOS/USTUR intercomparison. The focus areas for the study included: (1) the efficiency pattern along the leg phantom using Germanium detectors (experimental and computational), (2) the comparison of Monte Carlo (MC) results with experimental values in counting efficiency data and (3) the inflence of americium distribution in the bone material (volume or surface).

Since many decades, Bonner sphere spectrometers (BSSs) are routinely used for assessment of neutron spectra over a wide energy range from some meV to GeV. Typically, a spectrometer consists of a neutron detector sensitive to thermal neutrons located inside moderating polyethylene (PE) spheres of various sizes. Based on the response functions of the detector/sphere systems that must be calculated by Monte Carlo codes, an unfolding procedure is applied to deduce the present neutron spectrum from the count rates of the detectors. To start the unfolding procedure, a guess spectrum is required that includes some prior information on the physics of the investigated neutron spectrum, and that is iteratively modified to match the measured count rates. For the present investigation, a BSS-system consisting of an 3 He proportional counter and seventeen spheres containing PE or a combination of PE and lead is used. The system is used for example to measure secondary neutrons from cosmic radiation at mountain altitudes, or from high-energy accelerators outside the radiation shielding. A systematic study was performed to quantify the influence of the chosen guess spectrum and the number of iteration steps on the unfolded neutron spectrum, and on integral quantities deduced such as total neutron fluence or ambient dose equivalent. It turned out that none of these changes resulted in dose quantities that were more than a few percent different to those deduced when the optimised start spectrum was used. Similarly, use of the two different response matrices available for our BSS system provided similar values for the ambient dose equivalent.

Histological and histochemical studies on the salivary glands of the simuliidsB. erythrocephala and O. ornata. The salivary glands of the bloodsucking females of Boophthora erythrocephala and Odagmia ornata ornata differ in size and structure markedly from those of the nectar eating males. In the males there is only that part present which in shape, histology and histochemistry corresponds to the accessory gland in the females. The main gland of the females is regarded as a specialisation in relation with bloodfeeding. Three cell types were observed: accessory gland cells, main gland cells, and small main gland cells (these are confined to the region where the main gland enters the accessory gland). Zusammenfassung Die Speicheldrusen der blutsaugenden ♀♀ von Boophthora erythrocephala und Odagmia ornata ornata unterscheiden sich in Grose und Bau deutlich von denen der blutenbesuchenden ♂♂. Bei den Mannchen ist nur der der Nebendruse der Weibchen entsprechende Teil vorhanden. Diese beiden Drusen gleichen sich nicht nur in Grose und Form, sondern auch in ihrer Histologie, Ultrastruktur und Histochemie. Die Hauptdruse der ♀♀ wird als Spezialisierung im Zusammenhang mit dem Blutsaugen angesehen. 3 Zelltypen wurden beobachtet: Nebendrusenzellen, Hauptdrusenzellen und kleine Hauptdrusenzellen (diese kommen nur im Eintrittsbereich der Hauptdruse in die Nebendruse vor).

Field studies on egg-depositing in several Simuliids with special reference to Simulium argyreatum Meig. (Dipt. Simuliidae). The ways of egg-depositing so far known in middle european Simuliids are compared. The correlation between egg-depositing behavior, selective search for suitable locations and the resulting susceptibility of the developing egg towards variations of the water level is indicated. On the egg-deposition of Wilhelmia lineata at low water levels further observations are reported. The egg-deposition of Simulium sublacustre and Simulium argyreatum is described. The resistance of the eggs against desiccation and low temperature, the autogeny of females during the first cycle, their fertility and an abbreviated oogenesis enable Simulium argyreatum to develop successfully at high rate on overflow-devices and water outlets of ponds. Finally some technical suggestions concerning the use of traps in autecological and demecological studies are made. Zusammenfassung Die bisher festgestellten Formen der Eiablage mitteleuropaischer Simuliiden werden mitein-ander verglichen. Der Zusammenhang zwischen Eiablageverhalten, Aufsuchen bestimmter Eiablageplatze und der dadurch bedingten unterschiedlichen Gefahrdung der Eigelege ein-zelner Arten durch Pegelschwankungen wird verdeutlicht. Die Eiablage von Wilhelmia lineata bei niedrigem Wasserstand in Erganzung fruherer Beobachtungen sowie die Eiablage von Simulium sublacustre und von Simulium argyreatum werden beschrieben. Die Wider-standsfahigkeit der Eier gegenuber Trockenfallen und Kalte, die Autogenie der Mucken-weibchen im ersten Zyklus, ihre Fertilitat und die verkurzte Oogenese ermoglichen Simulium argyreatum die Uberlaufe und Teichauslaufe mit samtlichen praimaginalen Stadien dicht zu besetzen und den dort gegebenen, zum Teil fur sie ungunstigen Umweltfaktoren zu widerstehen. Abschliesend werden einige methodische Uberlegungen zur Analyse des Funktionskreises der Eiablage im Hinblick auf den Einsatz von Attrappen bei autokolo-gischen und demokologischen Analysen angestellt.

Further investigations on the potential natality of several simuliid species (Simuliidae, Dipt.) There is a linear correlation between body size and potential natality. Imagines, hatching after being kept in the laboratory for a longer period show a significantly reduced potential natality. This has to be considered in future analyses of potential natality in simuliids. The potential natality shows as identical annual rhythms in Boophthora erythrocephala, Wilhelmia lineata, Odagmia ornata and Simulium sublacustre. There are however differences in the starting point, which is to a certain extent species dependent and modifiable by local environmental factors. Zusammenfassung In erganzenden Untersuchungen zur potentiellen Natalitat verschiedener Simuliidenarten wurden folgende Ergebnisse erzielt: 1. Zwischen der Korpergrose und der potentiellen Natalitaẗ besteht ein linearer Zusammenhang. 2. Imagines, die erst nach langerem Aufenthalt im Labor schlupfen, weisen eine signifikant verringerte potentielle Natalitat auf. Dies mus kunftig bei derartigen Analysen uber die potentielle Natalitat von Kriebelmucken berucksichtigt werden. 3. Im Jahresrhythmus ist Boophthora erythrocephala, Wilhelmia lineata, Odagmia ornata und Simulium sublacustre ein gleichsinniger Kurvenverlauf der potentiellen Natalitat gemeinsam. Verschieden ist die Ausgangsbasis, die bis zu einem gewissen Grade artspezifisch determiniert ist und durch lokale Umwelteinflusse modifiziert wird.

Weevils (Araucariini, Cossoninae, Col.) on Araucaria araucana (Mol.) Koch in Chile with a breeding biology similar to bark beetles (Scolytoidea) Contrary to the majority of weevils the imagines of Araucarius major, A. minor, A. medius, A. chilensis penetrate into the phloem to lay their eggs like those of the bark beetles. Araucarius major and A. minor are even building galleries where the eggs were deposed. The first-mentioned species formes typical eggniches. The imagines of the Araucariini stay relatively long together with their eggs within the phloem. The breeding biological behavior of A. minor is not precisely determined. This species can lay eggs without building galleries too. The Araucarius species of the Araucaria araucana combine characters of Scolytidae and Curculionidae not only in their morphology but also in their breeding biology. Morphology, breeding biology, disjunct geographical distribution and their occurrence on phylogenetic relative old trees are evident for a phylogenetic relativ primitive tribus within the Rhynchophora. As far as known these Araucarius species are essentially concerned in the decomposition of outmoded Araucaria trees which are upset by wind or forest fire. In spite of an inproper trespass on the Araucaria forests of Chile by men and an intense infection (expecially observed by A. minor). A penetration of these beetles into the phloem of uninjured Araucaria trees was not observed. Zusammenfassung Die Imagines der Araucariini der Araucaria araucana zeigen im Gegensatz zur Mehrzahl der Curculioniden ein den Scolytiden ahnliches brutbiologisches Verhalten, indem sie in das Phloem eindringen, um dort Eier abzulegen. Araucarius major und A. minor fertigen sogar Muttergange an. A. major legt die Eier in Nischen ab. Die Imagines der Araucarius-Arten leben im Phloem mit der Brut relativ lange zusammen. Das brutbiologische Verhalten von A. minor ist nicht streng fixiert, da diese Art die Eier auch ohne Muttergange abzulegen vermag. Nicht nur morphologisch, sondern auch brutbiologisch besitzen die Araucarius-Arten aus der Araucaria araucana einen mosaikartigen Charakter. Morphologie, Brutbiologie, die Bindung an stammesgeschichtlich relativ alte Baumarten sowie ihre disjunkte geographische Verbreitung sprechen fur einen phylogenetisch relativ ursprunglichen Tribus innerhalb der Rhynchophora. Soweit bekannt ist, sind die Araucarius-Arten im wesentlichen am Abbau uberalterter, vom Wind geworfener und durch Waldbrand gescha-digter Araukarien beteiligt. Trotz unsachgemaser Eingriffe des Menschen in die Arau-karienwalder Chiles und der vor allem bei A. minor zu beobachtenden hohen Individuen-dichte, konnte ein Eindringen der Auraucariini in vollig gesunde Araukarien nicht beobachtet werden.

Studies on the quantitative analysis of the intensity of egg-depositing in Simuliidae (Diptera) The intensity of extended egg-depositing in Simuliids can be measured quantitatively with photography and planimetry. This was found by the permanent observation of the sampling sites and of unrecorded, dark coloured egg, as well as the development of the intensity of egg-depositing in comparable sampling sites. The method is described, beginning with the selection of the sampling sites and the collection of samples, the determination of the index of egg numbers of different Simuliid species differs in the mode of egg-depositing, in the position of eggs within the egg-deposit and in size and shape of the eggs. The use of this new method for studies of the dynamic of abundance and dispersion is discussed. Zusammenfassung Es wird uber die ersten Erfahrungen berichtet, die mit der Fotografie und Planimetrie bei der quantitativen Erfassung der Eiablageintensitat von Simuliiden mit weitgehend flachiger Eiablage gemacht wurden. Die neue Methode wird von der Festlegung der Probenabschnitte, der Probenaufnahme uber die Bestimmung des Eizahlindex bis zur Auswertung der Erhebungen beschrieben. Je nach Art der Eiablage, Position der Eier im Gelege sowie Grose und Form der Eier ist der Eizahlindex einzelner Simuliidenarten verschieden. Die fortlaufende Kontrolle der Probenabschnitte, der Kurvenverlauf der Eiablageintensitat in den vergleichbaren Einheiten sowie das Fehlen in der Embryogenese weit fortgeschrittener, dunkel gefarbter, nicht erfaster Eier bzw. Gelege beweisen die weitgehend vollstandige Registrierung der Eiablageplatze sowie der einzelnen Gelege. Auf die Weiterentwicklung und die Bedeutung von Fotografie und Planimetrie fur abundanz- und dispersionsdynamische Studien wird kurz hingewiesen.

On the population dynamics of Boophthora erythrocephala de Geer. The variation of the water level of a flowing water like the Aller has also in the autumn an influence on the developmet of eggs and on the dispersion of egg-laying places of Boophthora erythrocephala. When the water falls the eggs on the bank vegetation (e. g. Phalaris arundinacea) dry out and die. If the eggs are layed on aquatic plants, which keep in or near the water line even at a low water level like Potamogeton nodosus the first instar larvae can easily reach the currents. If the water in too high Boophthora cannot lay eggs on aquatic plants. If in such places there is no suitable bank-vegetation in the waterline the black flies are forced to find egg-laying places in different regions of the river. This leads to a shift of the local dispersion but does not change the abundance of the whole population in a larger area. The daily rate of destruction of eggs caused by desiccation or the lack of suitable egg-laying places caused by too high water levels was calculated for habitats with bank vegetation only, with aquatic plants only and with both types of vegetations. In regions with rich vegetation as well as the number of individuals on or near the banks the disturbance during egg-laying or egg development are normally fewest. They are less pronounced in autumn than in spring. Zusammenfassung Die Wasserstandsschwankungen eines Fliesgewassers wie der Aller beeinflussen auch im Herbst die Entwicklung der Eigelege und die Dispersion der Eiablageplatze von Boophthora erythrocephala. Bei sinkendem Pegel fallen die Eigelege auf den Uferpflanzen (z. B. Phalaris arundinacea) trocken und sterben ab (vgl. Fruhjahr, Ruhm 1969). Auf den aquatischen Pflanzen (z. B. Potamogeton nodosus), die den Wasserstandsschwankungen weitgehend folgen, bleiben sie an bzw. in der Wasserlinie, so das die Erstlarven ohne weiteres die Stromung erreichen konnen. Bei uberflutung kann Boophthora auf die aquatischen Pflanzen keine Eier ablegen. Die Mucken sind gezwungen, geeignete Eiablageplatze in anderen Abschnitten des Fliesgewassers aufzusuchen, falls auch Uferpflanzen an bzw. in der Wasserlinie fehlen. Auf diese Weise andert sich nur lokal die Dispersion der Eiablageplatze, nicht aber die Abundanz der gesamten Population innerhalb eines groseren Bereiches. Der tagliche Ausfall der Eigelege durch Vertrocknen bzw. der tagliche Ausfall der Eiablageplatze infolge uberflutung wurde nach einer schon fruher angegebenen Methode (Ruhm 1969) fur die Bereiche nur mit Uferpflanzen, nur mit aquatischen Pflanzen sowie mit Uferpflanzen und aquatischen Pflanzen ermittelt. In Bereichen mit einem differenzierten und relativ arten- sowie individuenreichen Pflanzenbestand am Ufer und in Ufernahe waren die Storungen der Eientwicklung bzw. der Eiablage am geringsten. Insgesamt waren sie im Herbst geringer als im Fruhjahr.

Zusammenfassung Von den an Saugern blutsaugenden Simuliidenarten des Aller-Leine-Gebie-tes verursacht nur Boophtbora erytbrocepbala in groserem Ausmase Er-krankungen und Todesfalle bei den Weidetieren. Im Kreis Celle verendeten 1966 mehr als 60 Rinder. Boophthora erythrocephala besiedelt vorzugsweise kleine, mittelgrose und grose Flusse der Tiefebene in Ost-, Mittel- und auch Westeuropa. Dagegen bevorzugt der Odagmia ornata-Komplex die Bache. Die Eiablage von Boophthora erythrocephala ist an den Bewuchs, die Pegelschwankungen und Stromungsverhaltnisse kleiner bis groser Tiefland-flusse weitgehend angepast. Die Eier konnen nur an Pflanzen abgelegt wer-den, die nahezu waagerecht an bzw. in der Wasserlinie liegen und benetzt werden. Das Verhalten bei der Eiablage sowie einzelne Faktoren, die die Ei-ablageplatze bestimmen, werden aufgezeigt. Der Einflus des Pflanzen-bewuchses der Uferregion und der ufernahen Bezirke sowie der des Pegel-standes werden eingehend erlautert. Die Pegelschwankungen beeinflussen, je nach ihrem zeitlichen Auftreten, auch die Entwicklung von Boophthora erythrocephala mehr oder minder stark.

First finding of Simulium sublacustre Davies 1966 in Central Europe. A contribution to the Simuliid fauna in the Aller-Leine-area. Simulium reptans, S. argyreatum, and S. sublacustre have been identified for the first time in the Aller-Leine-area. It is the first finding of S. sublacustre in Central Europe. The habitats are briefly described. The taxonomy of S. sublacruste is discussed, and the main taxonomic characteristics of the female are described. Zusammenfassung Simulium reptans, S. argyreatum und S. sublacustre werden erstmals fur das Aller-Leine-Gebiet nachgewiesen. Fur S. sublacustre ist es der Erstnachweis in Mitteleuropa. Die Fundorte werden kurz beschrieben. Auf die Taxonomie von S. sublacustre wird hingewiesen. Die wichtigsten taxonomischen Merkmale des Weibchens werden beschrieben.

Zusammenfassung Die Weiterentwicklung der Altlarven und Puppen von Boophthora erythrocephala wird vor allem durch den Einflus der Wassertemperaturen verlangsamt bzw. gehemmt, so das diese Stadien akkumuliert werden. Das Massenschlupfen der Imagines aus den akkumulier-ten Puppen setzt ein, wenn sich die Luft- und Wassertemperaturen rasch uber 10° C er-hohen. Im Durchschnitt der Jahre (1904-1966) ist dies im Aller-Leine-Gebiet zwischen dem 15. 4. und 20. 4. der Fall. Gunstige Witterungsbedingungen (z. B. feucht-warme Witterung) losen nach ein bis zwei Tagen einen Massenangriff auf die Weidetiere aus. Der Massenangriff unterbleibt, wenn beispielsweise relativ niedrige Lufttemperaturen oder Regen die Aktivitat der Mucken hemmen. In diesem Falle ist der Anflug verteilt. Auch durch das Anflugverhalten der Mucken kann es in Abhangigkeit vom Witterungsverlauf zu einer weiteren Akkumulation, vor allem in den Spatnachmittags- und Abendstunden, kommen. Bei einer hohen Imaginaldichte lost gerade dieser AkkumulationsefFekt Erkran-kungen und Todesfalle an Weidetieren aus.

on the desiccation of simuliid eggs (diptera, simuliidae) Because of the danger of desiccation due to emergence from water, the development of eggs to the point of hatching of first stage larvae depends on the type of deposite produced by females. with the eggs being laid on a substrate in the vicinity of the water surface the factors which came into play during emergence and which can influence development, can be classified according humidity, phase of embryonic development, substrate as well as those of the coincidence of time and place. Zusammenfassung Die Weiterentwicklung der Eigelege bis zum Schlupfen der Erstlarven ist je nach Art der Eiablage beim Trockenfallen unterschiedlich stark gefahrdet. Die Faktoren, die beim Trockenfallen der Gelege, die auf ein Substrat im Bereich des Wasserspiegels abgelegt werden, wirksam sind und die Entwicklung beeinflussen, werden nach Feuchtefaktor, Embryogenesephasen, Substrat sowie raumlich-zeitlicher Koinzidenz aufgeschlusselt. Wie in den Laborversuchen von Imhof und Smith (1979) mit Gelegen der nearktischen Simulium verecundum und S. vittatum unter konstanten Bedingungen konnte auch in Freilandversuchen unter naturlichen Verhaltnissen mit Gelegen von Boophthora erythrocephala und Simulium rostratum dieselbe Tendenz in der Fahigkeit, Trockenfallen zu uberstehen, nachgewiesen werden. Zu Beginn der Embryogenese uberstehen die Eier bei plotzlichem Trockenfallen eine langere Austrocknung. In der Augenfleckphase sind sie relativ widerstandsfahig, gegen Ende der Entwicklung nimmt ihre Widerstandsfahigkeit wieder ab. Die Bedeutung der zeitlichen Einklinkung der Eiablage der Weibchen in die Zeit vor Sonnenuntergang, durch die vor allem die Gefahrdung der Eier durch Austrocknung gemindert wird, wird ebenso wie die der widerstandsfahigen Augenfleckphase diapausierender Eier (z. B. Simulium nolleri) zur Uberbruckung besonders ungunstiger Milieubedingungen hervorgehoben. Auf die Notwendigkeit u. a. durch mikroklimatische Messungen die Analyse noch zu verbessern, wird hingewiesen.

Investigations on arrival of preimaginal stages of blackflies on artificial substrates Dependence of density of preimaginal stages on position, shape and duration of exposure of artificial substrates is investigated. Density on narrow stripes is higher than on wide ones. The strength of influence of the position of the substrates depends on the nature of parts of the running waters. The density of preimaginal stages within a limited period increases with the duration of exposure. Zusammenfassung Die auf kunstlichen Substraten erreichten Individuendichten der praimaginalen Stadien von Boophthora erythrocephala zeigten eine Abhangigkeit vom Profil des Fliesgewassers an der betreffenden Stelle bzw. von den daraus resultierenden Stromungsverhaltnissen. Eine Standardisierung der Form der kunstlichen Substrate ist notwendig, um vergleichbare Werte zu erhalten. Insbesondere ist die Wahl einer einheitlichen Breite von Bedeutung, da diese den grosten Einflus auf die Dichte ausubt. Die Expositionsdauer hat einen entscheidenden Einflus auf die Anzahl der Larven und Puppen, die sich auf den kunstlichen Substraten ansiedeln. Nur innerhalb einer begrenzten Zeitspanne nimmt mit langer werdender Expositionszeit die Dichte zu.

Zusammenfassung Die Wasserstandsschwankungen eines Fliesgewassers beeinflussen wahrend der ersten Generation im Fruhjahr die Mortalitat der Eigelege von Booph-thora erytbrocephala wegen ihres Eiablageverhaltens und des Angebotes an potentiellen Eiablageplatzen stark. Mit Hilfe einer speziellen Auswertungsmethode kann die tagliche Eimortalitat bestimmt werden. Das Ausmas der Beeinflussung bzw. des Ausfalles an Gelegen andert sich im Fruhjahr mit stark wechselndem Witterungscharakter von Jahr zu Jahr erheblich. Dies durfte mit ein Grund dafur sein, das B. erythrocephala im Untersuchungsgebiet in verschieden grosen Intervallen, oft erst nach Jahrzehnten, die Individuendichte erreicht, die eine unabdingbare Voraussetzung fur Schadfalle ist. Die Gelegeform, die zwischen Boopbtbora erythrocephala und dem Odagmia ornata-Komplex sehr verschieden ist, beeinflust nach Laborversuchen und Beobachtungen im Freiland die Schlupfperiode und Schlupfverteilung der Erstlarven. Die Schlupfperiode ist bei Boophthora erythrocephala wesentlich kurzer als beim Odagmia ornata-Komplex. Auf die Bedeutung der Dauer der Schlupfperiode und auf die Bedeutung der Schlupf Verteilung der Erstlarven fur die Populationsdynamik der betreffenden Arten und die daraus sich ergebende mehr oder minder grose Gefahrlichkeit als Schaderreger an Weidetieren wird hingewiesen.

Zusammenfassung Im Aller-Leine-Gebiet kommen zehn verschiedene Simuliidenarten bzw. Artenkomplexe vor. Funf Arten, namlich Boophthora erythrocephala, Odagmia ornata, Wilhelmia salopiensis, Wilhelmia equina und Simulium morsitans greifen die Weidetiere an. Boophthora erythrocephala sticht wahrend der ersten Flugwochen auch den Menschen. Die Schwerpunkte des Vorkommens liegen bei den einzelnen Arten verschieden. Einige Arten wie Odagmia ornata leben vorwiegend in den Bachen, andere wie Boophthora erythrocephala und die Wilhelmia-Arten in den mittelgrosen bis grosen Flussen. Nur Boophthora erythrocephala verursacht durch Stiche Erkrankungen und Todesfalle bei den Weidetieren. Boophthora erythrocephala kommt in der Leine nur noch relativ selten vor, wahrend sie in der Aller sehr haufig ist. Innerhalb des Untersuchungsgebietes lassen sich zur Zeit der permanente, der temporare und ephemere Herd unterscheiden. Die Schaden traten 1966 nur im engeren Bereich der permanenten Herde wahrend der ersten 14 Flugtage im April/Mai auf. Die Untersuchungen wurden durch eine Sachbeihilfe der Deutschen Forschungsgemeinschaft (Bad Godesberg) unterstutzt. Die Angaben uber das Schadauftreten von Kriebelmucken im Jahre 1966 erhielt ich von Herrn Regierungsveterinarrat Dr. U. FRITZE (Celle). Wertvolle Auskunfte erteilten mir die Wasser- und Schiffahrtsdirektion in Hannover und das Wasser- und Schiffahrtsamt in Celle. Hierfur sage ich meinen herzlichen Dank. Ebenso danke ich den Mitarbeitern des Institutes, Frl. v. SAMSON, Herrn HuNERBEIN und Herrn WOLFHAGEN.

Zusammenfassung 1 Die beiden neuen Nematodenarten Filenchus prelli n. sp. und Tylaphelenchus grosmannae n. sp. werden beschrieben. 2 Filenchus prelli n. sp. und Tylaphelenchus grosmannae n. sp. sind an Hylurgonotus brunneus Schedl (Col., Scolytidae) gebunden. Die juvenilen Weibchen bzw. die Dauerlarven werden unter einer auf dem Absturz haftenden Kotplatte verschleppt. 3 Die Vergesellschaftung mit Hylurgonotus brunneus wird erleichtert bzw. gebahnt durch: a. das brutbiologische Verhalten des Hylurgonotus brunneus b. die Konsistenz des Kotes, den der Transportwirt produziert c. die Form und Struktur der Elytren e. die Morphologie und Verhaltensweise der aufwandernden Entwicklungsstadien der Nematodenarten.

Investigations on the potential natality of various mammalophilic blackflies with special reference to Boophthora erythrocephala De Geer. The potential natality in the different generations of Boophthora erythrocephala showed a considerable variation during the course of the year. The natality was found highest in spring and lowest in July. The increase in autumn did not reach the values observed in spring. The climax in spring was also observed in Odagmia ornata ornata and Wilhelmia lineata. For Boophthora erythrocephala the rate of potential natality varied within different sites of a given running-water-system and from one of these water system to the other. The degree of this fluctuation appears to be different at different parts of the running water. Under special local conditions the potential natality of one population of Boophthora erythrocephala decreased continuously. This was in contrast to other populations of the same area. There was a higher real natality after the uptake of cattle blood than after the uptake of rabbit blood. With increasing physiological age that is with an increasing number of gonotrophic cycles the real and the potential natality decreased. The potential natality was not directly correlated with the body size of the female black flies. Boophthora-populations in which relatively big individuals prevailed did not show a significantly higher potential natality than populations of relatively small Simuliids. In one case the body size increased where as the potential natality decreased. Finally the factors which could possibly influence or govern potential natality are discussed. Zusammenfassung Die potentielle Natalitat von Boophthora erythrocephala schwankte innerhalb eines Jahres zwischen den verschiedenen Generationen relativ stark. Im Fruhjahr war sie am hochsten, im Juli am niedrigsten. Gegen den Herbst nahm die potentielle Natalitat, ohne die Werte der ersten Generation im Fruhjahr zu erreichen, wieder zu. Auch die potentielle Natalitat von Odagmia ornata ornata und Wilhelmia lineata lag im Fruhjahr am hochsten. Innerhalb eines Fliesgewassersystems zeigten die Boophthora-Populationen an verschiedenen Stellen eine zum Teil sehr unterschiedliche potentielle Natalitat, wie dies auch zwischen verschiedenen Systemen beoachtet werden konnte. Die potentielle Natalitat fluktuierte an ein- und derselben Stelle von Jahr zu Jahr. Offenbar fluktuiert sie an den einzelnen Abschnitten auf einem verschieden hohen Niveau. Unter besonderen lokalen Bedingungen nahm die potentielle Natalitat einer Boophthora-Population im Gegensatz zu den benachbarten Populationen fortlaufend ab. Die reale Natalitat war nach der Aufnahme von Rinderblut groser als nach der von Kaninchenblut. Mit zunehmendem physiologischen Alter bzw. mit Zunahme der Anzahl gonotrophischer Zyklen nahmen potentielle und reale Natalitat ab. Die potentielle Natalitat ist nicht unmittelbar von der Korpergrose der weiblichen Mucken abhangig. In einem Falle nahm die Korpergrose zu, wahrend die potentielle Natalitat abnahm. Abschliesend werden einige Uberlegungen zur Analyse des Faktorenkomplexes, der diese potentielle Natalitat beeinflussen bzw. steuern konnte, angestellt.

Neutron transport calculations are needed in many fields of radiation protection and medical physics. Neutron transport is often simulated with a Monte Carlo code, which allows the calculation of neutron dose distributions in different geometries, for example in voxel phantoms. So far little information is available about neutron transport below 15 MeV in tissue-like matter performed with the Monte Carlo code GEANT4. Therefore, we compared GEANT4 results of the ambient dose equivalent for neutron energies from 10 meV to 15 MeV with MCNP results and values published in ICRU 57. The GEANT4 code was found to be appropriate to calculate neutron and photon dose at energies below 15 MeV correctly. Furthermore, a method how to include a dose-assessment factor into the calculation was developed and tested.

The European Commission has funded within its 6th Framework Programme a three-year project (2005–2007) called CONRAD, COordinated Network for RAdiation Dosimetry. The organizational framework for this project was provided by the European radiation Dosimetry Group EURADOS. Work Package 6 of CONRAD dealt with “complex mixed radiation fields at workplaces” and in this context it organised a benchmark exercise, which included both measurements and calculations, in a stray radiation field at a high-energy particle accelerator at GSI, Germany. The aim was to intercompare the response of several types of active detectors and passive dosemeters in a well-characterised workplace field. The Monte Carlo simulations of the radiation field and the experimental determination of the neutron spectra with various Bonner Sphere Spectrometers are discussed in Rollet et al. (2008) and in Wiegel et al. (2008). This paper focuses on the intercomparison of the response of the dosemeters in terms of ambient dose equivalent. The paper describes in detail the detectors employed in the experiment, followed by a discussion of the results. A comparison is also made with the H*(10) values predicted by the Monte Carlo simulations and those measured by the BSS systems.