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The Type A standard uncertainty in Monte Carlo (MC) dose calculations is usually determined using the "history by history" method. Its applicability is based on the assumption that the central limit theorem (CLT) can be applied such that the dispersion of repeated calculations can be modeled by a Normal distribution. The justification for this assumption, however, is not obvious. The concept of stochastic quantities used in the field of microdosimetry offers an alternative approach to assess uncertainty. This leads to a new and simple expression.The value of the MC determined absorbed dose is considered a random variable which is comparable to the stochastic quantity specific energy, z. This quantity plays an important role in microdosimetry and in the definition of the quantity absorbed dose, D. One of the main features of z is that it is itself the product of two other random variables, specifically of the mean dose contribution in a 'single event' and of the mean number of such events. The term 'single event' signifies the sum of energies imparted by all correlated particles to the matter in a given volume. The similarity between the MC calculated absorbed dose and the specific energy is used to establish the 'event by event' method for the determination of the uncertainty. MC dose calculations were performed to test and compare both methods.It is shown that the dispersion of values obtained by MC dose calculations indeed depend on the product of the mean absorbed dose per event, and the number of events. Applying methods to obtain the variance of a product of two random variables, a simple formula for the assessment of uncertainties is obtained which is slightly different from the 'history by history' method. Interestingly, both formulas yield indistinguishable results. This finding is attributed to the large number of histories used in MC simulations. Due on the fact that the values of a MC calculated absorbed dose are the product of two approximately Normal distributions it can be demonstrated that the resulting product is also approximately normally distributed.The event by event approach appears to be more suitable than the history by history approach because it takes into account the randomness of the number of events involved in MC dose calculations. Under the condition of large numbers of histories, however, both approaches lead to the same simple expression for the determination of uncertainty in MC dose calculations. It is suggested to replace the formula currently used by the new expression. Finally, it turned out that the concept and ideas that were developed in the field of microdosimetry already 50 years ago can be usefully applied also in MC calculations.

Summary Potentially prolific petroleum systems remain hidden beneath igneous, high-impedance, and strongly attenuating flood basalt cover off the west coast of India. The highly heterogeneous and rugose basalt significantly inhibits the imaging and structural delineation of deeper plays. This case study demonstrates that, even with legacy marine streamer surveys, an appropriate workflow of combining suitable advanced technologies can help to overcome the long-standing challenges of sub-basalt imaging. The reprocessed data show clear uplift in the sub-basalt imaging and the inversion results validate the quality of the new data in relation to the well logs.

The first normal pressure (or stress) difference is directly computed from the local values of the pressure tensor components in molecular dynamics simulations of planar Poiseuille flow for a low molecular weight polymeric fluid. The resulting zero shear rate normal pressure difference agrees very well with the value computed using homogeneous shear simulations and the SLLOD algorithm, and less well with the result of the Coleman-Markowitz equation evaluated at equilibrium. This resolves doubts about the effects of homogeneous thermostats in homogeneous nonequilibrium molecular dynamics simulations.

ICRP Publication 116 on 'Conversion coefficients for radiological protection quantities for external radiation exposures', provides fluence-to-dose conversion coefficients for organ-absorbed doses and effective dose for various types of external exposures (ICRP 2010 ICRP Publication 116). The publication supersedes the ICRP Publication 74 (ICRP 1996 ICRP Publication 74, ICRU 1998 ICRU Report 57), including new particle types and expanding the energy ranges considered. The coefficients were calculated using the ICRP/ICRU computational phantoms (ICRP 2009 ICRP Publication 110) representing the reference adult male and reference adult female (ICRP 2002 ICRP Publication 89), together with a variety of Monte Carlo codes simulating the radiation transport in the body. Idealized whole-body irradiation from unidirectional and rotational parallel beams as well as isotropic irradiation was considered for a large variety of incident radiations and energy ranges. Comparison of the effective doses with operational quantities revealed that the latter quantities continue to provide a good approximation of effective dose for photons, neutrons and electrons for the 'conventional' energy ranges considered previously (ICRP 1996, ICRU 1998), but not at the higher energies of ICRP Publication 116.

Modern radiation protection is based on the principles of justification, limitation, and optimisation. Assessment of radiation risks for individuals or groups of individuals is, however, not a primary objective of radiological protection. The implementation of the principles of limitation and optimisation requires an appropriate quantification of radiation exposure. The International Commission on Radiological Protection (ICRP) has introduced effective dose as the principal radiological protection quantity to be used for setting and controlling dose limits for stochastic effects in the regulatory context, and for the practical implementation of the optimisation principle. Effective dose is the tissue weighted sum of radiation weighted organ and tissue doses of a reference person from exposure to external irradiations and internal emitters. The specific normalised values of tissue weighting factors are defined by ICRP for individual tissues, and used as an approximate age- and sex-averaged representation of the relative contribution of each tissue to the radiation detriment of stochastic effects from whole-body low-linear energy transfer irradiations. The rounded values of tissue and radiation weighting factors are chosen by ICRP on the basis of available scientific data from radiation epidemiology and radiation biology, and they are therefore subject to adjustment as new scientific information becomes available. Effective dose is a single, risk-related dosimetric quantity, used prospectively for planning and optimisation purposes, and retrospectively for demonstrating compliance with dose limits and constraints. In practical radiation protection, it has proven to be extremely useful.

Practical implementation of the International Commission on Radiological Protection's (ICRP) system of protection requires the availability of appropriate methods and data. The work of Committee 2 is concerned with the development of reference data and methods for the assessment of internal and external radiation exposure of workers and members of the public. This involves the development of reference biokinetic and dosimetric models, reference anatomical models of the human body, and reference anatomical and physiological data. Following ICRP's 2007 Recommendations, Committee 2 has focused on the provision of new reference dose coefficients for external and internal exposure. As well as specifying changes to the radiation and tissue weighting factors used in the calculation of protection quantities, the 2007 Recommendations introduced the use of reference anatomical phantoms based on medical imaging data, requiring explicit sex averaging of male and female organ-equivalent doses in the calculation of effective dose. In preparation for the calculation of new dose coefficients, Committee 2 and its task groups have provided updated nuclear decay data (ICRP Publication 107) and adult reference computational phantoms (ICRP Publication 110). New dose coefficients for external exposures of workers are complete (ICRP Publication 116), and work is in progress on a series of reports on internal dose coefficients to workers from inhaled and ingested radionuclides. Reference phantoms for children will also be provided and used in the calculation of dose coefficients for public exposures. Committee 2 also has task groups on exposures to radiation in space and on the use of effective dose.

Most research has investigated the seat-to-head transmissibility during single-axis excitations. Associations between head accelerations and discomfort or effects on vision were reported. Possible differences between the seat-to-head transmissibility determined during different vibration magnitudes with a variable number of excitation axes have not been systematically examined. An experimental study was performed with 8 male subjects sitting on a rigid seat with hands on a support. They were exposed to random whole-body vibration (E1=0.45 ms(-2), E2=0.90 ms(-2), and E3=1.80 ms(-2)) to single- and three-axis vibration. All translational and rotational seat-to-head transmissibilities were calculated. The effects of the factors vibration magnitude and number of axes on the peak modulus and frequency of the seat-to-head transmissibilities were tested. In general the head motions follow constant pattern. These pattern of head motions comprise a combination of rotational and translational shares of transmissions, i.e. the curves show a dependence on the factors 'vibration magnitude' and 'number of vibration axes'. Mechanical properties of the soft tissue, relative motions of body parts, and muscle reactions were supposed to cause the nonlinearities of the head. Future research should consider effects of multi-axis vibration, if conclusions shall be drawn for the evaluation of possible health effects and model validations.

The extent of intraspinal forces under whole-body vibration (WBV) depends on several factors like multiple excitations of different body parts, stature and posture. The effects of these forces are determined by individual tolerances. Hence, there is no direct and simple relationship between WBV and health risk of the lumbar spine. The current evaluation methods with respect to health cover only part of the WBV input to the human body and do not consider all associated factors. A set of 50 finite element (FE) models was developed, based on human anatomy and adapted to different typical postures of European drivers and their anthropometric parameters. Three-dimensional matrices of transfer functions simulate these models and permit a practicable routine computation by a Matlab program with graphical user interface to predict intraspinal compressive and shear forces caused by WBV-input in x-, y- and z-directions at the seat, backrest, feet and hands, measured on mobile machinery. The effects of posture and stature on predicted WBV-related internal loads are demonstrated, for example, of numerous WBV-measurements under field conditions. The predicted static and vibration-related peak-to-peak dynamic compressive forces are processed with a method of risk assessment based on cumulative fatigue failure and implemented as a Matlab-program. The resulting risk factors of the new assessment method are compared with existing evaluation procedures of ISO 2631-1 and ISO 2631-5. They reveal significant differences.

Modelling the response of the human body to occupational whole-body vibration provides the possibility of predicting the forces acting on the disc and/or endplates of lumbar vertebrae. Due to the complex structure of the human body, complex dynamic models based on human anatomy are required to adequately reflect the dynamic properties of the body. Based on experimental results the influence of posture and stature on the biodynamic behaviour of human subjects is described. To reflect the biodynamic response of different occupational groups of workers exposed to whole-body vibration, an existing model was adapted to five typical different postures and 10 representative statures registered of European drivers of heavy machines. The resulting 50 models were tested with white noise signals in three directions as input to the four interfaces buttock, back, feet, and hands. The results of the static and dynamic shares of the predicted spinal forces at six spinal levels show strong influences of the factors stature and posture. Calculated risk factors to estimate a probability of injuries reflect the influence of these factors. Based on these findings one frequency weighting curve for the assessment of vibration exposure is not sufficient to meet the variability of risks caused by different statures and postures. Relevance to Industry The results of the predicted spinal stress and possible health risk can be a basis to improve and to extend the range of measures of prevention, cab and seat design, or vibration isolation of seats. The measures should fit the wide range of spinal stress experienced by different percentile groups and different postures.

Imaging below shallow gas bodies is one geophysical challenge encountered in offshore Southeast Asia basins. There are two key components in addressing this challenge: 1) the derivation of an accurate, high-resolution, geologically consistent velocity model and 2) compensating for the loss in signal strength and frequency bandwidth due to absorption of the signal as it propagates through the gas bodies. In this study, we present the application of FWI and Q tomography to a shallow-water, shallow-gas dataset from offshore Southeast Asia. We demonstrate the successful ability of FWI and Q tomography to resolve the low P-wave velocities and high attenuation of shallow gas bodies and subsequently compensate for the complex kinematics and absorption during depth migration.

Imaging below shallow gas bodies is one geophysical challenge encountered in offshore Southeast Asia basins. There are two key components in addressing this challenge: 1) the derivation of an accurate, high-resolution, geologically consistent velocity model and 2) compensating for the loss in signal strength and frequency bandwidth due to absorption of the signal as it propagates through the gas bodies. In this study, we present the application of FWI and Q tomography to a shallow-water, shallow-gas dataset from offshore Southeast Asia. We demonstrate the successful ability of FWI and Q tomography to resolve the low P-wave velocities and high attenuation of shallow gas bodies and subsequently compensate for the complex kinematics and absorption during depth migration.

During the past decade, marine seismic acquisition evolved from narrow-azimuth (NAZ) to wide-azimuth (WAZ) geometries toward the latest offering of long-offset full-azimuth (FAZ) surveys. This advance in acquisition design is mainly driven by the demands of improved illumination in complex areas such as Gulf of Mexico (GOM) subsalt environments. Despite these acquisition and processing improvements, marine data still suffers from the ghost effect of free-surface reflections and resulting in constructive and destructive interference between the up- and down-going wavefields. If uncorrected, the ghost significantly reduces the bandwidth and distorts the phase of the recorded data and prevents us from producing a broadband image. Fortunately, the ghost effect is straightforward to simulate and, therefore, to correct, either prior to or during two-way wave equation inversion and imaging. Optimal use of this improved data, two-way wave equation algorithms such as reverse time migration (RTM) and full waveform inversion (FWI) are required. Their high-fidelity nature enables them to honor complex velocity fields with the accuracy required, particularly for migrating long-offset data, and as a result, for producing satisfactory model refinements and images when other methods fail. Finally, even with the best acquisition and imaging algorithms, RTM images can be further improved by post-imaging enhancements using vector image partitions (VIPs). We demonstrate an efficient workflow to maximize the power of broadband acquisition by applying velocity model building with FWI, imaging with RTM compensation for ghost effects in both steps, and outputting partial images for further optimization.

Seats with horizontal suspensions can help to reduce detrimental effects of whole-body vibration (WBV) on health, comfort and performance. Two seats were used to examine the effect of body mass and WBV-magnitude on the transmission of WBV from the seat base to the cushion. Both seats have suspension in the x-direction while Seat 2 has suspension also in the y-direction. Twelve subjects with a body mass ranging from 59.0 to 97.3 kg volunteered for the study. A set of anthropometric characteristics was acquired. Three magnitudes of WBV were used with a truck-like signal (Seat 1, 0.3–0.59 m s−2 wd-weighted rms values at the seat base, x-direction) and a tractor-like signal (Seat 2, 0.55–1.09 m s−2 wd-weighted rms values at the seat base, x-direction, 0.52–1.07 m s−2 wd-weighted rms values, y-direction). The magnitude of WBV had a significant effect on the transmissibility characterized by SEAT-values. A significant influence of the body mass on SEAT-values was found for the y-direction only. Other anthropometric characteristics proved to be more important for the prediction of SEAT values by multiple regressions. There was no significant correlation of SEAT-values, x-direction, with the body mass. Other anthropometric characteristics enabled a satisfactory prediction of SEAT values also for x-direction in several cases. Tests with only two subjects of extreme body mass are not suited to obtain comparable and representative results required for a comparison of different seats with a suspension in the x-direction. The effect of the WBV-magnitude on the WBV-transmissibility should be considered with the design, testing and application of suspended seats.

Data of the impedance and/or the apparent mass of the sitting human body during the exposure to whole-body vibration in z -direction using rigid seats were standardized in the ISO 5982. These data are available as target functions for model developments. Models developed on this data basis should also apply to driver seats with a soft seat and backrest cushion, although the qualitative different contact conditions were neglected. Due to insufficient technical prerequisites, the determination of forces at the interface between subject and soft seat was impossible until very recently. Results of studies during static conditions showed clear differences in the pressure distributions between the rigid and the soft contact areas. In this experimental study pressure distributions on a seat cushion were measured during whole-body vibration in z -direction (random signal in the frequency range between 0.3 and 20 Hz, vibration magnitudes 0.25, 0.8, and 1.6 m s −2 unweighted root mean square measured at the seat base) with a sampling rate of 32 m s. The apparent masses were calculated by the forces derived from the pressure distributions and accelerations measured at one point of the seat cushion near the buttocks. The moduli of the apparent masses derived for the soft seat were clearly lower than those determined for a rigid seat. These apparent masses showed a similar dependence on the vibration magnitude as the apparent mass functions derived in the usual way for rigid seats. Factors that could explain differences between the apparent mass functions derived for the soft and rigid seat were discussed and evaluated. The data of this study indicate the possibility and necessity to consider the contact conditions at the interface when deriving target functions for the model development. Recommendations for technical improvements and further experimental studies with driver seats were derived.

The stray radiation field outside the shielding of high-energy accelerators comprises neutrons, photons and charged particles with a wide range of energies. Often, accelerators operate by accelerating and ejecting short pulses of particles, creating an analogue, pulsed radiation field. The pulses can be as short as 10 micros with high instantaneous fluence rates and dose rates. Measurements of average dose equivalent (rate) for radiation protection purposes in these fields present a challenge for instrumentation. The performance of three instruments (i.e. a recombination chamber, the Sievert Instrument and a HANDI-TEPC) measuring total dose equivalent is compared in a high-energy reference radiation field (CERF) and a strongly pulsed, high-energy radiation field at the CERN proton synchrotron (PS).

WBV-exposures are often linked with forced postures as prolonged sitting, bent forward sitting, or sitting without a backrest. No quantitative data are available to describe the exposure–effect relationships for different conditions of seating, posture, and the biological variability of workers. Experiments and subsequent predictions of forces acting within the spine during WBV can help to improve the assessment of the health risk. An experimental study was performed with 39 male subjects sitting on a suspension seat with or with no backrest contact. They were exposed to random whole-body vibration with a weighted r.m.s. value of 0·6 m/s2 at a relaxed or a forward bending posture. A two-dimensional finite element model was used for the calculation of the internal spinal load. The model simulates the human response on a suspension driver seat. Individual exposure conditions were considered by including the transfer functions between the seat cushion and the seat base as well as between the backrest and the seat base for the calculation of the vibration input to the buttocks and to the back respectively. The average peak seat transmissibility was higher for the seat with the backrest, but the peak seat-to-head transmissibility was higher for the seat without the backrest for both postures. The peak transmissibilities between the accelerations at the seat base and the compressive forces at L5/S1 were highest for the seat without the backrest during the bending posture. Various biological effects can result from identical exposures combined with different backrest contact and postures. The backrest contact and posture conditions should not be neglected in the assessment of health risk caused by whole-body vibration.

The present study aimed to (1) employ the method for evaluation of vibration containing multiple shocks according to ISO/CD 2631-5:2014 (Model 1) and DIN SPEC 45697:2012 in a cohort of 537 professional drivers, (2) deliver the results for a re-analysis of epidemiological data obtained in the VIBRISKS study, (3) clarify the extent to which vibration acceleration and individual variables influence risk values, such as the daily compressive dose S(ed) and the risk factor R, and (4) compare the results with in vivo measurements and those obtained in previous studies with similar models. The risk factor R was influenced by the acceleration, lifetime exposure duration, sitting posture, age at the start of exposure and body mass/body mass index in order of decreasing effect. Age and annual and daily exposure duration had only a marginal effect. The daily compressive dose S(ed) and the risk factor R showed weak linear association with the daily vibration exposure A(8) and the vibration dose value VDV. The study revealed high shear forces in the lumbar spine.In a re-analysis of an epidemiological study of professional drivers, a software tool available with standards DIN SPEC 45697:2012 and ISO/CD 2631–5:2014 Model 1 was used to calculate the risk to the lumbar spine in terms of daily compressive dose S(ed) and risk factor R. The tool was found to be suitable for risk assessment in a large cohort.

Purpose – To investigate the relationships between low back symptoms and alternative measures of external dose and internal spinal dose in professional drivers exposed to whole body vibration (WBV). Methods – The occurrence of low back symptoms were investigated in a cohort of 537 drivers over a two-year follow up period. Low back pain (LBP), individual characteristics, and work-related risk factors were investigated with a structured questionnaire. Exposure to WBV was evaluated by means of measures of external dose (daily vibration exposure in terms of either equivalent continuous acceleration over an eight-hour period (A(8)) or vibration dose value according to the EU Directive on mechanical vibration) and measures of internal lumbar load (daily compressive dose Sed and risk factor R according to ISO/CD 2631-5 2014). Results – In the drivers’ cohort, the cumulative incidence of 12-month low back outcomes was 16.8% for LBP, 9.3% for chronic LBP, and 21.8% for sciatic pain. The measures of internal spinal load were better predictors of the occurrence of low back symptoms than the measures of daily vibration exposure. A two-fold increase in the risk estimates for low back outcomes was found in the upper quartile of the R factor (0.41-0.72 units) compared to the lower one (0.07-0.19 units). Conclusions – In this prospective cohort study, measures of internal spinal dose performed better than measures of daily vibration exposure (external dose) for the prediction of low back outcomes in professional drivers. The ISO boundary values of the risk factor R for low and high probabilities of adverse health effects on the lumbar spine tend to underestimate the health risk in professional drivers.

Measurements with high-rate two-dimensional imaging gaseous detectors require an adequate data acquisition system which allows to handle and store the detector information. For this purpose, a transient recorder system has been developed and tested at the University of Siegen. In contrast to many today’s systems there is no memory needed to store information which is redundant and not used for the final image reconstruction. Some current applications and measurements of the transient recorder system will be presented. It results that high rates up to 100 MHz can be processed without dead time loss at short time scale. However, also the problem of handling the massive data flux in the backend electronics needs to be addressed. Currently the avarage data acquisition time is limited e.g. by the PCI Bus to typically 1–2 MHz/4 Bytes. Another limitation is the global trigger which has been applied to the system. To solve these problems, some basic ideas about local asynchronous and parallel readout for applications in pixel detectors with big sensitive areas are discussed.

The operators of earth moving machinery are often exposed to a low frequency vibration environment caused by the movement of vehicles over uneven ground and the task carried out. The seat constitutes the least state of suspension before the driver. The efficiency of attenuation under consideration of the best design practice today is the basis for the revision of ISO 7096 for the testing seats for earth moving machinery. This standard requires the participation of two subjects with different body masses (52–55 kg; 98–103 kg). The aim of the study was to investigate (1) the extent and the influence of individual variability and posture change on the result of seat tests, and (2) the possibility of deducing representative results for the user population. 37 male subjects took part in the experimental investigations. They were exposed in three postures for 67 s to three acceleration signals in a vertical direction corresponding to the spectral classes (EM2, EM5, EM6) in ISO/DIS 7096 on two commercial suspension seats. The vertical accelerations were measured at the seat basis and at the interface between seat cushion and subject. The results of the analysis of variance show a significant influence of exposure, type of seat, and interactions exposure-by-posture, exposure-by-type of seat, and posture-by type of seat on the SEAT factor. Simple and multiple regression analyses were applied in order to test the predictability of the seat factor (SEAT) by anthropometric variables. The conclusions were drawn that the seat testing could be improved by (1) selecting subjects according to the 5th and 95th percentile masses of the population of vehicle or machinery users for which the seat is intended (ISO 10326), instead of fixed masses (ISO 7096), (2) considering other anthropometric parameters for the selection like the body height and body mass supported by the seat, and (3) the inclusion of several subjects near the 50th percentile in order to assess the variability of the SEAT factor.

The bremsstrahlung process in the domain of strong Coulomb fields has been investigated for and Ar target electrons colliding with He-like uranium ions at . The differential cross sections for bremsstrahlung were measured at laboratory observation angles of , , and . Substantial discrepancies were found between the experimental cross sections and the first-order Born approximation calculations. The reported data provide a new testing ground for non-perturbative treatment of the coupling between radiation and matter in the presence of strong fields.

In high-energy atomic collisions between bare high-Z projectiles and low-Z target atoms, an electron may be captured radiatively into an excited projectile state which subsequently decays by x-ray emission. This process is the inverse of two-photon{endash}one-electron ionization, in which the first photon resonantly excites an electron from the hydrogenic 1s{sub 1/2} ground state and a second photon ionizes the excited electron. We present an experimental and theoretical study of the angular distribution of the Ly-{alpha}{sub 1} (2p{sub 3/2}{r_arrow}1s{sub 1/2} ) x rays following radiative electron capture. From the observed anisotropic emission pattern a significant alignment of the intermediate 2p{sub 3/2} state is deduced. {copyright} {ital 1997} {ital The American Physical Society}

Whereas neutral 187Re has a half-life of ≈ 4 · 1010 yr, one expects for fully stripped 187Re75+ a half-life of < 100 yr, as it can decay into bound electronic states of the first excited state of the daughter isotope, 187Os75+. The latter decay occurs in hot stellar plasmas and must therefore be known if one wishes to infer from the 187Re187Os ratio found in meteorites the age of the material in our solar system. This decay was measured for the first time in an experiment performed at the heavy ion storage ring ESR of GSI. 187Re75+ ions were produced by stripping in a thick copper target after acceleration to 350 MeV per nucleon in the heavy ion synchrotron SIS. Up to 1.7 · 108 ions were stored in the ESR ring at a time. After different storage times (up to 5h), the hydrogen-like decay products were stripped in an internal argon gas jet target. The number of stripped 187Os76+ ions was determined in two independent experiments. In the first one the osmium ions were counted in a microstrip gas counter. In the second experiment, the 187Os76+ ions were still circulating in the storage ring and their number was determined non-destructively by Schottky spectroscopy. In both cases, a separation of the beta decay products from nuclear fragments produced either in the rest gas or the internal target was possible. One can safely exclude that a major fraction of the 187Os ions were produced by n-p exchange reactions. Rates for stripping in the gas jet and the relevant particle loss rates were determined independently.

The deceleration capabilities of the ESR have been used for the first time in a dedicated ground state QED experiment conducted at the gasjet target of the ring. By decelerating bare uranium ions from 358 MeV/u down to energies of as low as 49 MeV/u, X-ray spectra have been obtained which provide an abundant yield of characteristic X-ray transitions. The experiment demonstrates that, by choosing the appropriate beam energy and gasjet target, almost all excited projectile states can be selectively populated. Moreover, the experiment provides the first data for beam lifetimes of stored decelerated high-Z ions. Such data are essential for the design of future experiments dealing with decelerated ion beams far below 50 MeV/u.

Accelerations, a , in z - and x -directions were measured on the skin over spinous processes L 3 and L 4 in three subjects during sinusoidal whole-body vibration (WBV) at 4·5 and 8 Hz and 1·5 and 3·0 ms −2 r.m.s. A method for the prediction of bone accelerations was applied using measurements on the skin. Relative accelerations were calculated by subtracting a L4 from a L3 . The phase relations between relative accelerations in the z -direction indicating compression and the absolute maximum a z of L 4 exhibited marked between-subject variability. One subject was selected for a detailed analysis in the time domain of head, shoulder and upper trunk accelerations, and for comparison with an invasive study. Bidimensional acceleration data confirmed the suggestion that relative motions in the z -direction are combined with angular motions. The results indicate complex internal loads with coupled bending, compression and shear forces.

We observed the bound-state ${\ensuremath{\beta}}^{\ensuremath{-}}$ decay of fully ionized ${}^{187}$Re nuclei circulating in a storage ring. With two independent methods the time dependent growth of hydrogenlike ${}^{187}$Os ions has been measured and a half-life of $32.9\ifmmode\pm\else\textpm\fi{}2.0\mathrm{yr}$ for bare ${}^{187}$Re nuclei could be determined, to be compared with 42 Gyr for neutral ${}^{187}$Re atoms. With the resulting $\mathrm{log}\mathrm{ft}$ value of $7.87\ifmmode\pm\else\textpm\fi{}0.03$ the half-life of ${}^{187}$Re ions in any ionization state can be calculated. Thus one can correct the ${}^{187}$Re${\ensuremath{-}}^{187}$Os galactic chronometer calibration, by taking account of the ${\ensuremath{\beta}}^{\ensuremath{-}}$ decay enhancement in stellar interiors, which will lead to a more accurate estimate of the galactic age.

X-rays are emitted with the radiative recombination of free electrons in an electron cooler of a heavyion storage ring. Due to a small width of the X-ray lines, an observation angle close to 0° and an accurate determination of the ion velocity, the ground-state Lambshift of hydrogenlike uranium (470 ± 16) eV could be measured to an accuracy of 3.4%. A re-evaluation of a measurement of the 1s 1/2 Lambshift in hydrogenlike gold gave a new value of (202.3 ± 7.9) eV as compared to the former value of (212 ± 15) eV. The results are in excellent agreement with QED calculations and are more precise than any other measurements previously reported for a high-Z, hydrogenlike ion.

By decelerating highly-charged, very heavy ions to low energies in the storage and cooler ring, ESR, a new brilliant source for projectile x-rays has been obtained. In a first precision spectroscopy experiment up to 2·107 stored bare U92+ ions have been decelerated down to 49 MeV/u before detecting the characteristic projectile x-rays associated with one-electron capture at the ESR gas target. The Lyman, Balmer and Paschen series are distinctly observed for hydrogenic U91+ ions.

Central to the application of the system of protection recommended by the International Commission on Radiological Protection (ICRP) are the physical quantity, absorbed dose, and the protection quantities, equivalent and effective dose. These protection quantities are used to set dose limits, constraints and reference levels and to test compliance in the various activities of occupational and public exposure. They are also used in the assessment of doses from medical procedures. Effective dose in particular has proved to be a very valuable quantity that allows the summation of doses from external radiation and internal doses from different radionuclides in a single risk-related value. However, while it is possible to measure external radiation exposures and estimate internal exposures down to very low levels of dose, the associated risks, principally of cancer, are much less certain. Equivalent and effective doses are calculated using simplifying assumptions to apply to reference workers and members of the public for the purpose of control of exposures. Risks to individuals or specific population groups should be calculated not using these quantities but using best scientific information. The purpose of this note is to provide a short and readily accessible account of the purpose of the ICRP dosimetric quantities, how they are calculated, how they should be used, and how they relate to risk estimation.

The x-ray spectra induced by spontaneous capture of free cooling electrons into bare and hydrogenlike heavy ions have been observed. Au78+, Au79+ and U91+ ions were stored in the storage ring ESR at velocities between 60% and 65% of the velocity of light and the x rays were measured in coincidence with stored particles having captured one electron in the electron cooler. The lines observed can be attributed to the direct transition of cooling electrons into theK shell of the projectile and to the characteristicL →K transitions. The latter are mainly induced by capture into higher shells and subsequent cascade transitions. The measurements are compared to detailed calculations within the framework of presently available theories. Although the relative structure of the measured spectra is in fair agreement with the theoretical prediction, the total charge-changing rate in the electron cooler is about a factor of three smaller than expected.

High-LET radiation therapy using fast neutrons is being applied regularly at several centres worldwide and in the future, other types of radiation qualities, such as protons and heavier ions and boron neutron capture therapy (BNCT) are likely to be used. The neutron beams used are of considerably varying energy and thus considerable variations in the relative biological effectiveness (RBE) have been found. At present, no generally accepted method exists for the quantitative specification of these differences in radiation quality for clinical purposes. This is in clear discrepancy with the accuracy requirements in clinical dosimetry. An approach is presented which is based on a single parameter radiation quality characterization determined in combined microdosimetric and radiobiological experiments. It is shown that the method can meet the accuracy requirements of clinical dosimetry and that it is applicable within a concept of formalized procedure of clinical practice and experience ('clinical RBE').

La microdosimetrie determine les distributions des depots d'energie a l'echelle microscopique et tente de les interpreter comme l'impact du rayonnement dans une «cible» biologique. En comparant l'efficacite biologique des rayonnements, a partir d'hypotheses simples et des donnees radiobiologiques, elle apporte des solutions pratiques au probleme pose par la qualite du rayonnement en radioprotection et en radiotherapie sous la forme de modeles phenomenologiques. En visant la comprehension de l'action du rayonnement sur les structures biologiques, la nature de la «cible», l'interaction du rayonnement et les phenomenes biochimiques intracellulaires sont discutes

Spontaneous capture of free cooling electrons by bare high-Z ions leads to the emission of X rays which have been observed for the first time. The distinctive features of this X-ray source for precision spectroscopy of high-Z few-electron systems are demonstrated. They enabled a determination of the 1s Lamb shift of hydrogen-like Au78+ (212±15 eV) to an accuracy of 7%. This is more precise than any other measurement previously reported for a very heavy ion.