A passive neutron dosemeter (PND) for high-energy accelerators is described. The slide of the DVGN-01 personal dosemeter, which is placed at the center of a polyethylene moderator, is used as a thermal-neutron detector. The moderator includes a lead insert, which increases the sensitivity of the dosemeter to high-energy neutrons, and a cadmium filter. Optimization calculations of the dosemeter design parameters have been performed with respect to the energy dependence of the response in the range from the thermal energy to 1 GeV. The results of the calculations are in good agreement with the experimental data obtained in low-energy neutron reference fields. Comparative measurements using the PND and a low-energy passive dosemeter have been performed in the neutron fields outside the shield of the 70-GeV U-70 proton accelerator at the Institute for High Energy Physics.

New neutron reference fields, based on a 239Pu–Be source, intended for increasing the accuracy of measurements of neutron dosimeters and radiometers in the IHEP accelerator complex are described. A Bonner SB-RSU-01 spectrometer was used to measure the spectra of the neutron reference fields. The BON95 code was used to reconstruct the spectra; the initial spectra for the iteration procedure were determined by parameterization or by a calculation using the FAN15 code. Good agreement was obtained between the neutron spectra and the integral characteristics of the reference fields reconstructed by the two methods.

A method of modeling the transport of electrons and positrons with energies 1 keV–10 MeV implemented in the FAN15 code is described. The code takes account of multiple Coulomb scattering, fl uctuations of ionization losses, formation of δ-electrons, and Bremsstrahlung and x-ray photons. The EEDL and EADL evaluated data libraries are used in the calculations of Bremsstrahlung and emission of x-ray photons upon relaxation of ionized atoms. The computational results are compared with the experimental data on the energy, angular, and dose distributions of 0.5–10 MeV electrons in different absorbers.

The FAN15 software for the transfer of low-energy photons and neutrons is described. The constants base for modeling the interaction of the particles with matter is based on modern evaluated data libraries. The computational results obtained with FAN15 show good agreement with experimental and other computational data. This software can be used as a stand-alone code or a low-energy block for the HADRON high-energy hadron transfer code.

The algorithms and basic equations of a novel evaporation model that have been implemented in the program package EVAP15 are detailed. The level density of an excited nucleus is described by the composite Gilbert–Cameron formula with parameter values as suggested by the IAEA working group RIPL-3. Special attention is paid to the cross sections of inverse reactions and, in particular, to those for the interactions of low-energy neutrons with nuclei and for crossing of the Coulomb barrier by low-energy charged particles. The model predictions are compared with a large volume of experimental data on the spectra of particles emitted in the reactions ( n , xn ), ( n , xp ), and ( n , xα ) induced by neutrons with energy near 14 MeV and on the four spectra for the reaction ( p , xp ) induced by 62-MeV protons.

Different versions of the design of a neutron dosemeter for high energy accelerators based on a fast scintillation lithium glass detector of thermal neutrons are considered. The detector is placed at the center of a polyethylene moderator shaped as a sphere, a cylinder, or a truncated cylinder with a lead insert used to increase the dosemeter sensitivity to neutrons with energies above 20 MeV. Calculations of the design parameters have been performed to optimize the angular and energy dependences of the response at energies ranging from the thermal energy to 1 GeV. The best results have been obtained for dosemeter versions comprising a boron filter along with the lead insert. In this case, the instrument has the lowest mass. The dosemeter has been developed for use in the radiation monitoring systems of the IHEP U-70 accelerator complex and other accelerators. It can also be used outside shields of reactors and other low-energy facilities.

A mathematical model of a detector has been constructed using the comparison of calculated and experimental values of the photon detection efficiency of a gamma-spectrometer based on a high-purity germanium detector. The method and program for calculating the correction for coincidences in low-activity measurements for radionuclides with complex decay schemes have been created. This study makes it possible to calculate the photon detection efficiency in the cases, where the working standards for the considered measurement conditions are absent, and to take the correction of the experimental data for the cascade summation into account.

The bismuth activation cross sections were calculated within the scope of the generalized cascade model in the 15- to 1000-MeV range of neutron energies. These data were used in comparison with two experiments performed at the Institute for High Energy Physics and Rutherford Appleton Laboratory and in unfolding of high-energy neutron spectra from results of measurements. The equilibrium shape of the cascade peak in high-energy neutron spectra outside thick shields was confirmed.

The technique and results of measurements performed of the neutron spectrum behind the top shielding of the U-70 experimental hall using a Bonner spectrometer based on indium and carbon activation detectors are presented. The integral characteristics of the neutron field are presented; such a field could be useful in various areas of dosimetry, radiation physics, and radiobiology, in assuring radiological safety during flights in airplanes and in space, as well as in the study of malfunctions induced in microelectronics by high-energy neutrons.

Total nucleon reaction cross sections with nuclei are necessary as input data for various applications, such as transport calculations or prediction of different radiation effects. Nevertheless, experimental data until now are rather scarce and contradictory whereas reliable theoretical models are absent. The optical model of nuclear reactions, most often used for the calculation of reaction cross sections, cannot be applied for extrapolation into the regions where no experimental data exist, due to the large number of free parameters in the phenomenological optical potential. This paper presents the calculations of nucleon reaction cross sections in the frame of the new generalised cascade model. The model includes the self-consistent description of the nucleon density and potential in nuclei, accurate consideration of the refraction process by the mean field, non-locality of the nuclear interaction and reduction of the nucleon-nucleon interaction cross sections in dense nuclear matter. The results of the calculations show overall good agreement with available experimental data in wide ranges of nuclei and nucleon energies from 10 MeV to 10 GeV without free model parameters. The present model may be a good base for the creation of global systematics of total nucleon reaction cross sections.

A new model of single event upsets (SEUs), created in memory cells by heavy ions and high energy hadrons, has been developed. The model takes into account the spatial distribution of charge collection efficiency over the cell area not considered in previous approaches. Three-dimensional calculations made by the HADRON code have shown good agreement with experimental data for the energy dependence of proton SEU cross sections, sensitive depths and other SEU observables. The model is promising for prediction of SEU rates for memory chips exposed in space and in high-energy experiments as well as for the development of a high-energy neutron dosemeter based on the SEU effect.

This work is devoted to the calculation of responses as functions of neutron energy for a paired set of Andersson–Braun rem counters, which is commercially available. Different Monte Carlo codes such as MCNP, LAHET, HADRON and MCNPX were applied in the calculations. The study extended to frontal, lateral and isotropic neutron incidence. For an estimation of the contribution of charged high-energy particles to the reading, the responses to protons and pions were also determined. The results obtained give good bases for the practical use of the new instrument in high-energy neutron fields.

A recent version of the high-energy transport code HADRON is described in part of the hadron event generator. The improved cascade-exciton model was extensively tested by the experimental data for double differential cross sections for the (N,xN′)-reactions. Good agreement with experiment in wide ranges of nucleon energies and target nuclei confirms reliability of the new physical model. Ways for further improvements are discussed.

High-energy spectra of neutrons, protons and pions behind the top shielding of CERN-CEC reference field facility have been calculated using the MARS’95 and HADRON Monte Carlo transport codes. The results are in good agreement with experimental data and FLUKA simulations.

This paper describes a neutron spectrometry experiment at the summit of the mountain Zugspitze. The measured spectral neutron fluence rate is compared with results of particle transport calculations of cosmic primaries and secondaries down to the depth of 700 g.cm-2 in the atmosphere. The results may serve as a basis for the estimation of neutron exposure to air crews and other persons flying frequently.

Calculations of the ambient dose equivalent conversion factors for neutron energies from 20 MeV to 5 GeV have been performed using the Monte Carlo high energy transport code HADRON. The kerma approximation extended to the high energy region was applied in the calculations. The results obtained are compared with the previous data for an infinite slab 30 cm thick as well as with the recent calculations for the ICRU sphere. The influence of the phantom shape and dimension is expected to be fairly unimportant for high energy radiations. The discrepancies in dose equivalent data are explained mainly by incorrect quality factors of secondary charged particles used in earlier calculations. Another conclusion is that the ambient dose equivalent H*(10) satisfies the requirement of conservativity for high energy radiations in practical cases of radiation fields outside shields.