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For proper environmental radiation monitoring, a method to simultaneously determine ambient dose equivalent rate and radioactivity concentration in the air by using a newly developed scintillation spectrometer, namely a CeBr3 spectrometer was investigated. The performance of the proposed method, including energy dependence, angular dependence and the linearity of the spectrometer (i.e. the dose rate dependence of its response), was verified by a series of measurements, conducted according to the procedure of inter-comparison of detectors used for early warning network performed by the European Radiation Dosimetry Group (EURADOS). Measurement results show that the proposed method is suitable for environmental radiation monitoring purposes. After thorough tests, the investigation on obtaining activity concentration in air from the pulse height spectrum of γ-ray was demonstrated in the laboratory by using a point-like sealed 133Ba source to simulate an artificial increase of ambient dose equivalent rate due to a radioactive cloud containing 131I and 133Xe. The photon fluence rate was obtained from the pulse height spectrum by using the unfolding method, and the activity concentration in air for radionuclides of interest could be estimated from the obtained photon fluence rate by applying the conversion coefficient evaluated via a Monte Carlo calculation.

Due to the need for harmonization of passive dosimetry and the requirements of the international standards in the area of environmental monitoring in radiation protection, multiple types of various passive dosimetry systems based on different ionizing radiation detection mechanisms were subjected to extensive performance testing. In the scope of the EMPIR project 16ENV04 Preparedness, the performance of 12 passive dosimetry systems was examined in radiation fields of different photon energies, angles of incidence and ambient dose equivalent rates in order to estimate their performance in the almost omni-directionally and energetically broad radiation field of the natural environment. The use of different detectors, holders, calibrations, measurement procedures and uncertainties, leads to differences in the measured data. Prior investigations and harmonization of passive dosimetry systems are necessary to achieve reliable and comparable dose measurements in Europe.

The energy dependent conversion factors from measured photon pulse height spectra to ambient dose equivalent (H*(10)) of three different detectors based on the scintillation materials CeBr_3, LaBr3 and SrI2 were simulated with the three Monte Carlo Codes, GEANT4, MCNP and PENELOPE, respectively. The performance of the detection systems, using the calculated conversion factors (fitted to response functions), is demonstrated for different scenarios ranging from laboratory conditions (i.e. a precisely defined radiation field in a calibration facility) to a free-field irradiation scenario produced by the natural radioactivity at a large lawn. With very simple geometric models of the detector systems, the response function of scintillation based dosemeters can be derived from the aforementioned Monte Carlo simulations with an accuracy of the measured doses in H*(10) of ±10% in an photon energy range from 100 keV to 3000 keV, as being typical for natural environmental gamma radiation.

The Universitat Politecnica de Catalunya (UPC), the Physikalisch-Technische Bundesanstalt (PTB) and the German Federal Office of Radiation Protection (BfS) have analysed the response of a 2”x2” (diameter x height) NaI and a 1.5”x1.5” CeBr3 scintillators, and a 1500 mm3 CZT semiconductor airborne spectrometric detectors mounted on Unmanned Aerial Vehicles (UAV) in a comparison campaign carried out in the aerial site of Mollerussa (Spain). The background count rates and H*(10) rates measured by the airborne detectors at the aerial site and with a 137Cs point source of 345 MBq have been compared at altitudes of 1.5 m, 10 m, 20 m, 40 m, 60 m and 100 m a.g.l. (above ground level). Furthermore, natural activity concentrations in soil have been calculated with different methodologies using the spectra acquired in the background flights. The airborne detectors together with the implemented calculation methodologies show in general a good agreement. The CZT detector has a significant lower efficiency than both scintillators due to the smaller size and, therefore shows poorer results. Finally, parallel flights over the 137Cs point source at 10 m, 20 m and 40 m were carried to evaluate the methods implemented by the three teams to localize point sources. The three systems were able to locate properly the source. The project 16ENV04 “Metrology for mobile detection of ionising radiation following a nuclear or radiological incident” has received funding from the EMPIR programme co-financed by the participating states and from the European Union’s Horizon 2020 research and innovation programme.

For the upgrade of existing dosimetric early warning networks in Europe spectrometric detectors based on CeBr 3 , LaBr 3 , SrI 2 , and CdZnTe are investigated as possible substitutes for the current detector generation which is mainly based on gas filled detectors. The additional information on the nuclide vector which can be derived from the spectra of γ -radiation is highly useful for an appropriate response in case of a nuclear or radiological accident. The measured γ -spectra will be converted into ambient dose equivalent H * ( 10 ) using a method where the spectrum is subdivided into multiple energy bands. For each band the conversion coefficients from count rate to dose rate is determined. The derivation of these conversion coefficients is explained in this work. Both experimental and simulative approaches are investigated using quasi-mono-energetic γ -sources and synthetic spectra from Monte-Carlo simulations to determine the conversion coefficients for each detector type. Finally, precision of the obtained characterization is checked by irradiation of the detectors in different well-known photon fields with traceable dose rates.

The responses of electronic dose rate meters were investigated in a large volume radon chamber at PTB in a wide range of radon activity concentrations. The measurements were conducted under controlled laboratory conditions and measured dose rate data are compared with Monte-Carlo simulations. Consequences concerning environmental monitoring are described. A further result is that the direct measurement of the dose rates produced by radon progeny in air is hardly possible in radon atmospheres with high activity concentrations, because the major contribution of measured dose rates is produced by radon progeny on the housing of the dose rate instruments. The latter effect largely depends on the ability of surfaces to absorb radon progeny. The Monte-Carlo simulations revealed quantitative results on the height of the single contributions to the total dose rate measured in the radon chamber. When environmental dose rate measurements are performed, the plate-out on detectors can be neglected.

Concerning ionising radiation monitoring in the environment in areas which, by normal means, are inaccessible, e.g. in contaminated areas after a nuclear or radiological incident, the use of highly mobile systems, comprising of unmanned airborne vehicles equipped with ionising radiation detector, is advised in order to protect the health and the life of first responders. As a promising candidate, the compact solid-state spectrometer based on CdZnTe is characterised by performing irradiations in the reference radionuclide radiation fields of PTB. The energydependent conversion coefficients are derived from recorded pulse-height spectra, and they enable calculation of the operational radiation protection quantity, ambient dose equivalent rate, directly from the spectrum without deconvolution. The validity of the conversion coefficients was evaluated by determining the deviation of the calculated dose rate from the reference ambient dose equivalent rate for the 226Ra radionuclide, available at the Underground Dosimetry Laboratory (UDO II) of PTB. By employing the derived conversion coefficients, the detector “linearity” (dose rate dependence of the response) was checked in the 137Cs reference fields of different ambient dose equivalent rates ranging from 25 nSv/h up to 1 µSv/h. The deviation of the calculated 226Ra dose rate from the achieved reference value was +2%

In the aftermath of a nuclear or radiological accident, an extended mapping of reliable dose rate values is of key importance for any governmental decision and countermeasures. Presently, numerous dosimetry network stations, operated by the national governments of the member states in Europe, provide such dose rate data on an hourly basis. Nevertheless, there are large areas in Europe that are not covered at all by these early warning networks and other areas that show only a low density of governmental network stations. Hence, there may be a significant lack of information in case of a nuclear or radiological emergency. As a consequence of the Fukushima Daiichi nuclear power plant accidents in 2011, a number of non-governmental radiation monitoring networks (NRMN) appeared on the internet, providing dose rate data based on stationary as well as on mobile measurements of ionizing radiation by laypersons. Especially the mobile detectors are able to cover large areas in short time. Therefore, it is of considerable importance to investigate the feasibility of using dose rate data from non-governmental networks as a complementary input to the European Radiological Data Exchange Platform (EURDEP). Within the European Metrology Program for Innovation and Research (EMPIR), the project 16ENV04 “Preparedness” has studied the metrological relevance of such non-governmental dose rate data (also called crowd-sourced radiological monitoring) in the most comprehensive way so far. Sixteen different dose rate detector systems (in general 4 of each type, plus 2 types with 2 detectors, i.e. 68 detectors in total) used in NRMN have been investigated for the reliability of their data and the corresponding networks, and their data provision to the public were analyzed. The most relevant performance parameters of dosimetry systems (detector's inherent background, energy dependence and linearity of the response as well as the response to secondary cosmic radiation, the sensitivity to small increases of the dose rate and finally the stability of the detector's indication at various climatic conditions - temperature and humidity) have been investigated for fourteen representative types of non-governmental dose rate measuring instruments. Results of this comprehensive performance study of the simple, light-weighted and cheap dose rate meters used in NRMN, and conclusions on the feasibility of using their data for governmental monitoring in case of a nuclear or radiological emergency are presented. © 2021 The Authors

One of the objectives of the EMPIR project 16ENV04 “Preparedness” is the harmonization of methodologies for the measurement of doses with passive dosimetry systems for environmental radiation monitoring in the aftermath of a nuclear or radiological event. In such cases, measurements are often performed at low radiation dose rates, close to the detection limit of the passive systems. The parameters which may affect the dosimetric results of a passive dosimetry system are analyzed and four laboratories quantitatively evaluate the uncertainties of their passive dosimetry systems. Typical uncertainties of five dosimetric systems in four European countries are compared and the main sources of uncertainty are analyzed using the results of a questionnaire compiled for this specific purpose. To compute the characteristic limits of a passive dosimetry system according to standard ISO 11929, the study of the uncertainty of the system is the first step. In this work the uncertainty budget as well as the characteristic limits (decision thresholds and detection limits) are evaluated and the limitations and strengths of a complete analysis of all parameters are presented.

As a consequence of the Chernobyl nuclear power plant accident in 1986, all European countries have installed automatic dosimetry network stations as well as air sampling systems for the monitoring of airborne radioactivity. In Europe, at present, almost 5,000 stations measure dose rate values in nearly real time. In addition, a few hundred air samplers are operated. Most of them need extended accumulation times with no real-time capability. National dose rate data are provided to the European Commission (EC) via the EUropean Radiological Data Exchange Platform (EURDEP). In case of a nuclear emergency with transboundary implications, the EC may issue momentous recommendations to EU member states based on the radiological data collected by EURDEP. These recommendations may affect millions of people and could have severe economic and sociological consequences. Therefore, the reliability of the EURDEP data is of key importance. Unfortunately, the dose rate and activity concentration data are not harmonized between the different networks. Therefore, within the framework of the European Metrology Research Programme (EMRP), 16 European institutions formed the consortium MetroERM with the aim to improve the metrological foundation of measurements and to introduce a pan-European harmonization for the collation and evaluation of radiological data in early warning network systems. In addition, a new generation of detector systems based on spectrometers capable of providing both reliable dose rate values as well as nuclide specific information in real time are in development. The MetroERM project and its first results will be presented and discussed in this article.

A new generation of dosemeters, based on the scintillators LaBr3, CeBr3 and SrI2, read out with conventional photomultipliers, to be used in the field of environmental gamma-radiation monitoring, was investigated. The main features of these new instruments and especially their outdoor performance, studied by long-term investigations under real weather conditions, are presented. The systems were tested at the reference sites for environmental radiation of the Physikalisch-Technische Bundesanstalt. The measurements are compared with that of well characterized classical dose rate reference instruments to demonstrate the suitability of new spectrometers for environmental dose rate monitoring even in adverse weather conditions. Their potential to replace the (mainly Geiger Muller based) dose rate meters operated in about 5000 European early waning network stations as well as in environmental radiation monitoring in general is shown.

After the Chernobyl nuclear power plant accident in 1986, all Member States of the European Union have installed area dose rate monitoring networks so that radiological incidents can be detected quickly. However, the different technical approaches and procedures led to inconsistencies in the area dose rate data. In the last 15 years, the working group 'Environmental Radiation Monitoring' of the European Radiation Dosimetry Group (EURADOS) has performed six pan-European intercomparison exercises for detector systems operated in national dosimetric early warning networks. These intercomparisons aimed at the harmonisation of area dose rate measurements of radiation monitoring stations in Europe. The intercomparisons revealed differences in technical properties of the dose rate monitoring systems as well as in the calibration and measuring methods that led to deviations of measured dose rate values by a factor of 5 or more under the same measuring conditions. As a result of the intercomparisons, the accuracy of dose rate measurements could be improved considerably. Further progress in metrologically correct measurements of area dose rates in the natural environment and necessary steps towards a metrologically sound pan-European system for environmental radiation monitoring will be discussed.

Background: In 1998 Baden-Wuerttemberg (BW), a federal state in southwest Germany with 10.8 million inhabitants, implemented a structured medical concept for the treatment of acute stroke. Methods: Since 2004 participation in the BW stroke database is mandatory for all hospitals in BW involved in acute stroke care. The stroke database includes all inpatients ≥18 years of age who have suffered an ischemic or hemorrhagic stroke within 7 days before hospitalization. This article presents methodological aspects and first results of the BW stroke database in the time period from 2007 to 2011. Results: Annual inclusion numbers increased continuously (29,422 vs. 35,724, p < 0.001). Median age of stroke onset was stable over time. The proportion of stroke patients ≥80 years increased from 36.9 to 38.8% (p < 0.001). Rates of patients treated in neurology departments rose from 50.7 to 60.9% (p < 0.001) and numbers of patients treated in stroke units rose from 59.1 to 68.4% (p < 0.001). Admission via emergency medical systems increased from 42.8 to 49.7% (p < 0.001) and arrival within 3 h increased from 29.8 to 34.4% (p < 0.001). Conclusion: We present results from a large, prospective and consecutive stroke patient database. This first analysis demonstrates a continuous increase of absolute and relative numbers of stroke patients who arrive within 3 h after onset, are hospitalized in neurology departments and treated in stroke units, and are aged ≥80 years.

International audience; The European Radiation Dosimetry Group (EURADOS) has been organising dosimetry intercomparisons for many years in response to an identified requirement from individual monitoring services (IMS) for independent performance tests for dosimetry systems. The participation in intercomparisons gives IMS the opportunity to show compliance with their own quality management system, compare results with other participants and develop plans for improving their dosimetry systems. In response to growing demand, EURADOS has increased the number of intercomparisons for external radiation dosimetry. Most of these fit into the programme of self-financing intercomparisons for dosemeters routinely used by IMS. This programme is being coordinated by EURADOS working group 2 (WG2). Up to now, this programme has included four intercomparisons for whole-body dosemeters in photon fields, one for extremity dosemeters in photon and beta fields, and one for whole-body dosemeters in neutron fields. Other EURADOS working groups have organised additional intercomparisons including events in 2014 for eye-lens dosemeters and passive area dosemeters for environmental monitoring. In this paper, the organisation and achievements of these intercomparisons are compared in detail focusing on the similarities and differences in their execution. © The Author 2016. Published by Oxford University Press. All rights reserved.

The German DRG system defines specialized treatments through a set of minimal requirements, the documentation of which and its assessment by external specialists of the medical service of the statutory health insurance causing frictions between rehabilitation hospitals and the medical service. It is especially problematic to make a clear distinction between nursing care and treatment. To reduce frictions and interface problems, a catalogue of acts of therapy performed by nurses was agreed for neurological early rehabilitation in Baden-Wurttemberg. This Elzach concept and catalogue describe therapeutic nursing in neurological rehabilitation and increase transparency and accountability both for providers and cost carriers.

The physical properties of alpha-Al(2)O(3):C are very similar to that of quartz, which make it an attractive dosimetric material for geological and archaeological dating applications. Storage experiments in an ultra-low-radiation underground environment (UDO at PTB) and gamma-ray spectrometry show that the optically stimulated luminescence (OSL) signal of this material does neither suffer from a significant inherent background caused by traces of radionuclides (

PTB operates an Underground laboratory for DOsimetry and spectrometry (UDO) in the Asse salt mine at a depth of 490 m below the ground. The ambient dose equivalent rate at UDO is only 2 nSv h(-1). Therefore, UDO is well suited for dosimetry at low dose rates as well as for other low-level measurements. UDO provides the only photon calibration facility worldwide for calibrations at low dose rates (comparable to those in the natural environment and even below), which are traceable to primary standards. Photon fields are generated by using radioactive sources of the following nuclides: (241)Am, (57)Co, (137)Cs, (60)Co and (226)Ra. The dose rates and mean photon energy values at the reference point of this calibration facility were calculated analytically after performing calibration measurements using a secondary standard. This procedure ensures for the traceability of the reference dose rate values to PTB's primary standards. The mean photon energy of each spectrum was calculated with respect to the different quantities air kerma and ambient dose equivalent, respectively. The assessment of the uncertainties of the basic properties of the photon calibration fields will be described.

After the Chernobyl nuclear power plant accident in 1986, followed by the Fukushima Nuclear power plant accident 25 years later, it became obvious that real-time information is required to quickly gain radiological information. As a consequence, the European countries established early warning network systems with the aim to provide an immediate warning in case of a major radiological emergency, to supply reliable information on area dose rates, contamination levels, radioactivity concentrations in air and finally to assess public exposure. This is relevant for governmental decisions on intervention measures in an emergency situation. Since different methods are used by national environmental monitoring systems to measure area dose rate values and activity concentrations, there are significant differences in the results provided by different countries. Because European and neighboring countries report area dose rate data to a central data base operated on behalf of the European Commission, the comparability of the data is crucial for its meaningful interpretation, especially in the case of a nuclear accident with transboundary implications. Only by harmonizing measuring methods and data evaluation, is the comparability of the dose rate data ensured. This publication concentrates on technical requirements and methods with the goal to effectively harmonize area dose rate monitoring data provided by automatic early warning network systems. The requirements and procedures laid down in this publication are based on studies within the MetroERM project, taking into account realistic technical approaches and tested procedures.

In 2006, the European Radiation Dosimetry (EURADOS) Working Group on Environmental Radiation Monitoring (WG3) organised a third European intercomparison of dosimetry systems operated in national early warning networks. Similar to the intercomparisons in 1999 and 2002, the main aim of this exercise was to support the process of harmonisation of area monitoring in Europe by providing the network operators with basic information on the calibration and performance of their dosimetry systems. In order to characterise these systems, their following basic parameters were investigated: the response to terrestrial and cosmic radiation, the detectors' inherent background, the response at low dose rates, the energy dependence of the response as well as the sensitivity of the detector systems to small changes of the dose rate in a natural environmental radiation field. In the 2006 EURADOS intercomparison, scientists from seven countries participated to study the characteristics of 11 detector systems. All results are presented in terms of the operational quantity ambient dose equivalent, H*(10). The advent of this quantity has caused the development of new detector systems for area monitoring. Some of these new systems participated in a EURADOS intercomparison for the first time. The results are consistently presented together with uncertainties so that statistical effects can be distinguished from real detector features, which improves the interpretation of the results. By using the results of this intercomparison, some detectors were re-calibrated. The achievable improvements concerning harmonisation in dose-rate measurements in the natural environment are discussed.

When using gamma-ray spectrometry performed deep underground, it is possible to measure 60Co activities down to 0.1 mBq in steel samples of some 100 g without any pre-concentration. It is thus still possible to measure 60Co induced by neutrons from the atomic bomb explosion in Hiroshima in pieces of steel collected at distances up to about 1200 m slant range. The results of non-destructive measurements of eight steel samples are compared with the 1986 Dose Re-Evaluation (DS86) model calculations.

Neutron activated items from the vicinity of the place where the JCO criticality accident occurred have been used to determine the fluence of neutrons around the facility and in nearby residential areas. By using underground laboratories for measuring the activation products, it is possible to extend the study to also cover radionuclides with very low activities from long-lived radionuclides. The present study describes γ-ray spectrometry measurements undertaken in a range of underground laboratories for the purpose of measuring 60 Co more than 2 years after the criticality event. The measurements show that neutron fluence determined from 60 Co activity is in agreement with previous measurements using the short-lived radionuclides 51 Cr and 59 Fe. Limits on contamination of the samples with 60 Co are evaluated and shown to not greatly affect the utility of neutron fluence determinations using 60 Co activation.

Etched track Makrofol detectors combined with Kodak BN-1 boron (n,alpha) converters were used inside a 30 cm diameter polyethylene (PE) sphere for the measurement of the neutron ambient dose equivalent. We found unexpectedly high values for the neutron dose equivalent of about 250 microSv instead of 25 microSv for 3 months' exposure in the natural environment. Results from such detectors etched in the authors' labortories revealed that the tracks could only be induced by spontaneous particle emission from the converter. This was confirmed by track diameter analysis and additional special etching of deeper detector layers. Eight surface barrier detectors were used simultaneosly for several days to measure the alpha spectra of the converters. The overall count rate in the energy range 2.5-7.5 MeV was 10 alpha particles d(-1) x cm(-2) for most of the converters and about 10 times less than this for some of them. To identify the nuclides responsible for alpha emission within the converters, gamma spectra of converters were measured for 8 days using a highly sensitive low-background gamma spectrometry system The spectra clearly indicated a small contamination (10 +/- 3 mBq) of the converter foils with 225Ra (T(1/2) = 5.7 y) typically originating from 232Th.

To investigate muon-induced nuclear reactions leading to the production of radionuclides, targets made of C9H12, SiO2 ,A l 2O3, Al, S, CaCO3, Fe, Ni, Cu, Gd, Yb and Tl were irradiated with 100 and 190 GeV muons in the NA54 experimental setup at CERN. The radionuclide concentrations were measured with accelerator mass spectrometry and Q-spectroscopy. Results are presented for the corresponding partial formation cross-sections. Several of the long-lived and short-lived radionuclides studied are also produced by fast cosmic ray muons in the atmosphere and at depths underground. Because of their importance to earth sciences investigations, calculations of the depth dependence of production rates by fast cosmic ray muons have been made. : 2002 Elsevier Science B.V. All rights reserved.

Since the Chemobyl accident many countries now operate large national networks of radiation detectors that continuously monitor radiation levels in order to give early warning of nuclear accidents having transboundary implications. The networks are used to provide data to assist in determining the action that should be implemented in that country. However, each country has its own unique system of detection. These are based either on Geiger-Miller counters, high pressure ionisation chambers, scintillation detectors, proportional counters, passive detectors or spectrometry systems; or mixtures of these detectors are used. During an accident the data produced by such systems will be exchanged between countries within the European Communities, (EC) and as required by the IAEA's Early Warning Convention between the rest of the world and Europe. It is therefore important to ensure that such data should be harmonised so that it can be accurately interpreted by other countries and by international organisations. To assist with such harmonisation an intercomparison was held during May/June 1999 at the Riso Natural Environmental Radiation Measurement Station in Denmark and at the PTB underground laboratory for dosimetry and spectrometry (UDO) in Germany. The main aim of the intercomparison was to help ensure that results reported by different countries during a nuclear accident will be consistent and comparable. It is important that during an emergency the measurements of the plume doses or contamination levels reported from network systems will not show significant increments or decrements at national boundaries that are due to inadequate calibration, or to different measurement quantities being used for different systems. Seven countries participated in the intercomparison with detectors used in their national network system as well as with other detectors being developed for future use. This report summarises the important results arising from the intercomparison.

The PTB operates an underground laboratory for dosimetry and spectrometry (UDO). It is situated at the Asse salt mine near Braunschweig, at a depth of 925 m below ground. Due to the low air kerma rate of less than 0.7 nGy.h -1 inside the laboratory, UDO is an excellent place for investigating the inherent background of radiation detectors and for providing 'background free' calibrations of highly sensitive environmental monitoring systems. The UDO laboratory has been involved in several EC-sponsored intercomparisons of environmental dose rate meters, electronic dosemeters, thermoluminescence dosemeters (TLDs) and spectrometers. The laboratory facilities and its role in the 1999 intercomparison of environmental monitors used in national networks of early warning systems, sponsored by EURADOS, are described. The experiments performed during this intercomparison gave the participants from seven countries the opportunity to determine the inherent background of their equipment as well as its linearity at very low dose rates, generated by different 137 Cs sources. In addition, the participants measured the photon energy dependence of their detector responses using collimated photon radiation fields produced by 241 Am, 57 Co, 137 Cs and 60 Co sources. The dose rates of these calibration fields are traceable to the PTB's primary standard measuring devices. Initial results of the measurements performed at UDO during this EURADOS intercomparison are presented.

A measurement of direct photon production in {sup 208}Pb+ {sup 208}Pb collisions at 158A GeV has been carried out in the CERN WA98 experiment. The invariant yield of direct photons in central collisions is extracted as a function of transverse momentum in the interval 0.5 1.5 GeV/c . The result constitutes the first observation of direct photons in ultrarelativistic heavy-ion collisions. It could be significant for diagnosis of quark-gluon-plasma formation.

In 1991, the Physikalisch-Technische Bundesanstalt established an underground laboratory for dosimetry and spectrometry (UDO) at the Asse salt mine, near Braunschweig. Due to the depth of 925 m below ground (equivalent to about 2100 m of water), the cosmic ray muon intensity in this facility is reduced by more than 5 orders of magnitude. In addition, the low specific activity of the pure rock salt and a low concentration of radon lead to an extremely low ambient dose equivalent rate of less than 1 nSv/h. The UDO facility is therefore well suited for dosimetry at very low dose rates, as well as for Ultra-Low-Background (ULB) gamma-ray spectrometry. In 1998, a coaxial low-background HPGe-detector (88% relative efficiency, FWHM 2.0 keV at 1.33 MeV) with an extended shielding (20 cm low-activity lead, 1 cm electrolytic copper, N2-flushing) was installed at UDO; the count rate per mass of germanium, integrated over the energy range from 40 to 2750 keV, was measured to be 0.012 s(-1) kg(-1). Results from test measurements and first applications are reported. The design of a ULB gamma-detector system, presently under construction, is described.

The Delta(++)-resonance production in central 158 A GeV Pb-208 + Pb-208 collisions at the CERN SPS has been studied. The Delta(++) production was estimated from the invariant mass spectrum of p pi(+)-pairs by subtracting a mixed event background. The measured Delta(++) abundance is compared with the results from other experiments at lower energies, and with a model calculation assuming thermal and chemical equilibrium. (C) 2000 Elsevier Science B.V. All rights reserved.

An event-by-event analysis of the azimuthal angular correlation with respect to the reaction plane has been carried out for K+ and pi(+) emission near mid-rapidity in 158 A . GeV Pb + Pb collisions. In semi-central collisions, K+ mesons are found to be preferentially emitted out of the reaction plane, while pi(+) mesons are emitted in the reaction plane. The results suggest that the kaon emission is influenced by in-medium potential effects in addition to collective flow effects. (C) 1999 Published by Elsevier Science B.V. All rights reserved.

Recent results of the WA98 experiment with Pb induced reactions at 158. A GeV are presented. The scaling properties of the transverse energy and the charged particle multiplicity at midrapidity with the number of participants is studied. Neutral pion spectra are compared to hydrodynamical parameterizations. The analysis of collective flow at target rapidity and at midrapidity is presented. The status of the study of direct photons and the search for isospin fluctuations is discussed.

Neutral pion production in central 158A GeV [sup 208]Pb+ [sup 208] Pb collisions has been studied in the WA98 experiment at the CERN Super Proton Synchrotron. The [pi][sup 0] transverse mass spectrum has been analyzed in terms of a thermal model with hydrodynamic expansion. The high accuracy and large kinematic coverage of the measurement allow one to limit previously noted ambiguities in the extracted freeze-out parameters. The results are shown to be sensitive to the shape of the velocity distribution at freeze-out. [copyright] [ital 1999] [ital The American Physical Society ]

The production of neutral pions in 158A GeV {sup 208}Pb+ {sup 208}Pb collisions has been studied in the WA98 experiment at the CERN Super Proton Synchrotron (SPS). Transverse momentum spectra are studied for the range 0.3{le}m{sub T}{minus}m{sub 0}{le}4.0 GeV /c . The results for central collisions are compared to various models. The centrality dependence of the neutral pion spectral shape and yield is investigated. An invariance of the spectral shape and a simple scaling of the yield with the number of participating nucleons is observed for centralities with greater than about 30thinspthinspparticipating nucleons. This is most naturally explained by assuming an equilibrated system. {copyright} {ital 1998} {ital The American Physical Society }

We present recent results obtained with the WA98 experiment at CERN SPS. The experiment consists of large acceptance hadron and photon spectrometers which allow to study many aspects of heavy ion collisions. We use event-by-event measurements of charged and neutral particle multiplicity to establish the limit on the prodution of Disoriented Chiral Condensates. We use the Plastic Ball detector together with a set of tracking chambers to study collective flow. The tracking chambers together with the excellent particle identification allow us to study the production of Δ ++ . The high resolution photon calorimeter array allows us to study inclusive photon and π 0 spectra and search for excess direct photons.

Anisotropic transverse flow has been studied with a magnetic spectrometer at midrapidity and the Plastic Ball detector at target rapidity in the WA98 experiment. Our preliminary results show the existence of directed and elliptic flow in semi-central Pb+Pb collisions. The magnitude of the directed flow is found to be significantly smaller than those observed at the AGS energies.

The restoration of chiral symmetry and its subsequent breaking through a phase transition has been predicted to create regions of Disoriented Chiral Condensates (DCC). This phenomenon has been predicted to cause anomalous fluctuations in the relative production of charged and neutral pions in high-energy hadronic and nuclear collisions. The WA98 experiment has been used to measure charged and photon multiplicities in the central region of 158 AGeV Pb+Pb collisions at the CERN SPS. In a sample of 212646 events, no clear DCC signal can be distinguished. Using a simple DCC model, we have set a 90% C.L. upper limit on the maximum DCC production allowed by the data., 20 Pages, LaTeX, uses elsart.cls, 8 eps figures included, submitted to Physics Letters B

In a precision measurement of the spectrum of ultracold neutrons as it evolves during storage in a “neutron bottle" we have observed an indication of a surprising heating by ≈ 10-10 eV, occurring during the initial several 100 s of storage. We have not found any simple explanation. The data are, however, consistent with unconventional ideas proposed previously by two of us.

Neutron multiplicities after antiproton-induced fission have been determined as a function of the total mass of the fission fragments. Pre- and postscission neutron multiplicities of the reaction {bar p}+{sup 238}U have been deduced using the moving-source parametrization of the neutron energy spectra by Maxwellian distributions. A postscission multiplicity of 6.3(6) neutrons out of 20.0(10) in total emitted neutrons in fission indicates that fission is a rather slow process. The increase of the evaporative prescission neutron multiplicity is about 80{percent} of the total increase of evaporative neutrons as a measure of excitation energy. The postscission multiplicity gets only 20{percent} of the total increase, thus indicating that the nucleus has only a moderate excitation energy at the moment of scission. The results are compared with standard cascade-evaporation calculations predicting a much lower number of evaporated prescission neutrons as the experiment shows. This is a strong indication of the importance of dissipative effects in the fission process. Application of dissipative effects like a saddle-to-scission delay time and nuclear viscosity in the model calculation describes the experimental results much better. {copyright} {ital 1997} {ital The American Physical Society}

The depth dependent in-situ production of radionuclides has been measured and calculated taking into account spallation reactions, reactions with captured negative and fast muons and background reactions. The following probabilities f ∗ of particle emission channels after μ− capture have been measured:O(μ−,νμαpxn)10Be, x = 1–3, f ∗ = (5.2 ± 0.6) × 10 −3 and S(μ−,νμαxn)26Al, x = 2–4, 6, f ∗ = (1.4 ± 0.4) × 10 −3 . From the oxygen irradiation result for 10Be and the known channel probability from silicon to 26Al, the production ratio of 26Al to 10Be after μ− capture in quartz has been deduced to be P( 26 Al ) P( 10 Be ) = 7.2 ± 1.2 . The nucleon emission probabilities after μ− capture have been determined for iron. The particle emission channel Fe(μ−,νμxn)53Mn, x = 1, 3–5 was estimated to 0.05 ± 0.02. Natural depth profiles of 26Al in quartz have been measured in Northern Bavaria up to depths of 250 m and have been compared with calculated profiles taking erosion into account. From this comparison, the erosion rate in the last million years has been obtained to be about 10–20 μm/y.

The first evidence of directed flow at 158 A GeV Pb + Pb collisions is observed using the Plastic Ball detector in WA98 experiment. The azimuthal angle of the total transverse energy, Phi(o), is determined for each event using the observed protons in the Plastic Ball. A clear azimuthal asymmetry of fragments is observed with respect to Phi(o). The degree of azimuthal asymmetry is found to be largest in mid-central collisions, which is consistent with the picture of the collective flow.The p(t) spectra of particles measured in the mid-rapidity spectrometer has been studied in conjunction with the Plastic Ball, and different p(t) slopes with respect to Phi(o) for proton and pi(+) are observed.

For measuring the quantity ambient dose equivalent, H*(10), various passive photon and neutron dosemeters have been newly developed and are used in particular for the monitoring of nuclear facilities in the radiation field of the natural ambient radiation. Since 2005, the Physikalisch-Technische Bundesanstalt (PTB) has been performing intercomparisons to study fundamental properties and the long-term behaviour of area dosemeters under real environmental conditions, i.e. the accuracy of photon and neutron measurements performed in the complex natural radiation field. Measuring bodies from four European countries were the participants, including Germany. The goal was, on the one hand, quality assurance for existing passive dosemeters and measurement procedures and, on the other hand, the experimental investigation of whether the requirements of the appropriate standards and guidelines are met in practical use.

Information on the neutron distribution in the nuclear periphery was obtained by the annihilation of stopped antiprotons and the yield of residual nuclei. The last atomic transitions of the antiproton before annihilation gives complementary results. Properties of very hot nuclei (up to 1 GeV) after annihilation of stopped antiprotons were studied by neutron emission and fission. Absolute prob­ abilities of fission induced by stopped and fast antiprotons were determined. The experimental data are compared with elaborate calculations taking into account the annihilation process, the fast cascade and pre-equilibrium emission, thermalisation, particle evaporation and fission.