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The high energy Monte Carlo codes MARS and FLUKA are compared as applied to calculations of neutron spectra in the atmosphere resulting from interactions of primary galactic cosmic rays (GCR) with the nuclei in the atmosphere. The calculational strategies of either code are discussed. The primary galactic spectrum at the top of the atmosphere and the model used for the atmosphere are presented in detail. MARS is used to calculate neutron energy spectra which before had been calculated with FLUKA and measured with Bonner spheres. The comparison shows acceptable agreement. Therefore, MARS is used to provide new data for the analysis of dosimetric measurements at flight altitudes. The new data encompass calculated angular distributions and energy spectra of neutrons, protons, photons and pions for the geographical position of Braunschweig and the Zugspitze. In addition, the influence of aluminium layers on these spectra is studied. These new data are expected to provide valuable support in the analysis of dosimetric measurements at flight altitudes. Throughout the paper, emphasis is placed on the discussion of the main sources of variance for these calculations.

new rem counter with a response tailored to match the shape of H*(10)/Φ as defined by ICRU and ICRP has been developed recently in the frame of a Technology Transfer Project of the Research Centre Karlsruhe with the industrial partner EG&G Berthold, Wildbad. In this paper, a carefully established, consistent fluence and ambient dose equivalent response function is provided for this detector as well as the effective response calculated for more than 500 neutron spectra from a catalogue.

One of the major problems encountered in dose assessment for neutron radiation protection derives from the imperfect dose equivalent response of the devices used for monitoring. To investigate the performance of such devices in realistic neutron fields and to optimise calibration procedures, knowledge of both the prevalent spectral fluences and the energy response of the dosemeters is required. To facilitate this and similar studies, a database has been developed comprising a catalogue of neutron spectra and energy-dependent response functions together with a software package to manipulate the data in the catalogue. The range of data, features of the programs, and examples for radiation protection applications are described.

A mathematical formalism for evaluating a multi-sensor dosemeter is presented. The formalism is tested for a personal dosemeter in a series of neutron spectra taken from a catalogue and an example for estimating the uncertainties is given.

The response of practicable neutron dosemeters for routine use generally does not match the conversion function from fluence for radiation protection quantities such as the ambient dose equivalent. As a consequence, significant errors may be encountered when monitoring in a neutron energy spectrum different from that in which the dosemeter was calibrated, which is almost inevitably the case. A database of neutron energy spectra, detector response functions, and dosimetric conversion factors has been developed, and has been used to investigate the extent of this problem. The paper examines various ways of improving dosemeter response by 'ranking' spectra and deriving correction factors based upon this ordering. In the case of area monitoring, a combination of two responses (e.g. a rem meter and TEPC) may serve to improve the measurement of dose equivalent.

Quality factors and fluence-to-ambient and fluence-to-personal-dose equivalent conversion factors for neutrons have been recalculated for neutrons with energies ranging from thermal to 20 MeV. The new calculations are based on the recommendations given in ICRU Publication 60 for the quality factor and on stopping power data for protons and alpha particles as recommended in the ICRU Report 49

The use of appropriate phantoms for the calibration of individual neutron monitors is necessary, as the shape and the material of the phantom significantly influence the reading of such monitors. The International Commission on Radiation Units and Measurements (ICRU) considers the ICRU sphere to be suitable. This in practice may be questionable. A systematic numerical study of the influence of various phantoms on the readings of thermoluminescent detectors (TLDs) and etched track detectors (TEDs) has been performed. Elliptical cylinders consisting of ICRU soft tissue or polyethylene and resembling the trunk of an exposed person, with or without a cavity simulating the lung volume, have been compared with the ICRU sphere. In certain irradiation situations the readings of dosemeters exposed on elliptical cylindrical phantoms can be appreciably higher than on the ICRU sphere. If fast neutrons cannot be neglected, it may be necessary to use an anthropomorphic calibration phantom for both albedo dosemeters and etched track detectors.