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A deep-penetration shielding experiment was performed at the CERN High-energy AcceleRator Mixed-field (CHARM) facility. The protons (24 GeV/c) were injected into a 50-cm-thick copper target and the...

Measurement of total ionizing dose in a radiation field is efficiently carried out by ionisation chambers. The paper details the design of a mixed-signal ASIC for the front-end electronics of ionisation chambers. A single chip solution for ultra-low current measurement is designed by combining the current processing analog section realized using low leakage thick gate transistors and the data handling digital section implemented using fast thin gate transistors. The design succeeds in limiting the cross coupling between the two circuit domains using deep n-wells and guard rings. The ASIC fabricated in 130 nm technology attains a wide dynamic range of −7 fA to −20μA with maximum error in measurement less than ±4 %. The ASIC occupies an area of 3.52 mm 2 and has a total power consumption of 17.4 mW. The femtoampere range input leakage current of the ASIC contributed primarily by the ESD diodes was found to be varying exponentially with temperature. Dose rate measurements from 5 μ Sv/h to 7.4 Sv/h is demonstrated by interfacing the ASIC to an ionisation chamber.

A measurement of high-energy neutron streaming was performed through a maze at the CERN (Conseil Européen pour la Recherche Nucléaire) High-energy AcceleRator Mixed-field (CHARM) facility. The protons of 24 GeV/c were injected onto a 50-cm-thick copper target and the released neutrons were streamed through a maze with several corridor-legs horizontally designed with the shield walls in the facility. Streaming neutrons were measured by using aluminum activation detectors placed at 10 locations in the maze. From the radionuclide production rate in the activation detectors, the attenuation profile along the maze was obtained for the reaction of 27Al(n,α)24Na. Monte Carlo simulations performed with two codes, the Particle and Heavy Ion Transport System (PHITS) and CERN FLUktuierende KAskade (FLUKA), gave good agreements with the measurements within a factor of 1.7 for the production rates ranging over more than 3 orders of magnitude.

To devise an activation technique for characterizing mixed radiation fields, secondary particles from a copper target irradiated by 24 GeV/c protons were measured at the CERN High-energy AcceleRator Mixed field facility (CHARM). Activation detector sets consisting of aluminum, niobium, indium, and bismuth, were placed at 30 cm from the target at angles of 15° to 160° with respect to the beam axis. The nuclides generated in these detectors due to irradiation by secondary particles were analyzed by γ -ray spectrometry, and the angular distributions of the production rates were obtained. The results of Monte Carlo calculations using FLUKA code was compared with the experimental results. The calculated results well agreed with the measured data at all angles. The influence of competitive reactions on the measured data were also evaluated by FLUKA. The following nuclear reactions, with low affectivity by competitive reactions, were identified as promising tools for characterizing mixed radiation fields: the 115In( n , n ′ ) 115 m In reaction for detecting neutrons emitted by the evaporation process, the 93Nb( γ , n ) 92 m Nb reaction for verifying the photon distribution generated by neutral-pion decay ( π 0 → 2 γ ), and the 209Bi( p , 4 n )206Po reaction, which detects secondary protons.

Maintenance activities and operations of high-energy particle accelerators can lead to the collection of radioactive equipment as well as waste materials. In order to ensure their proper classification as radioactive or non-radioactive, one has to quantify the activities of radionuclides produced. According to the regulatory requirements in Switzerland, these activities need to be compared with nuclide-specific clearance limits. In particular, a new set of clearance limits was introduced by the Swiss authorities in January 2018, leading to more conservative values for a number of relevant radionuclides. We describe in this paper a new methodology based on dose-rate measurements to classify potentially radioactive objects at the exit of the CERN accelerator complex. This methodology concerns the specific material compositions typically found at CERN and takes into account the latest clearance limits introduced by the Swiss authorities.

The CERN High-Energy AcceleRator Mixed field (CHARM) facility provides a secondary particle field, produced by irradiating a thick target with 24 GeV/c protons supplied by the proton synchrotron. In order to investigate the thermalization process of secondary neutrons in the CHARM facility, we measured the thermal neutrons using the gold foil activation method. Bare and Cd-covered gold foils were placed at 35 positions to deduce the thermal neutron distribution in the CHARM facility. The 197Au(n, γ )198Au reaction rates and thermal neutron fluxes measured in this study were compared with the Monte Carlo simulation codes, PHITS, FLUKA, and MARS. The comparison between the measured and simulated values gives an agreement better than a factor of two. Besides, we investigated the simple empirical formula to estimate a thermal neutron flux in the accelerator room, ϕ th = CQ / S , where Q is the neutron source intensity and S is the total surface area of a room. The coefficient C estimated in this study did not significantly depend on the incident proton beam energy.

The reproduction of neutron fluence derived by the unfolding method was confirmed by simulating an experiment at Cern High energy AcceleRator Mixed field facility (CHARM). Fluences on an NE213 scintillator located at positions surrounded with shields were calculated using PHITS. A neutron light output spectrum and response matrix were calculated according to the calculated fluence. Furthermore, response matrices with simple distributions of neutron incident position and direction on the scintillator were also prepared because a response matrix with guessed distributions is used in measurements. In spite of using response matrices with different distributions, the unfolded fluence agreed with each other, unless the distribution was focused on a position. The agreement of the fluences enables us to measure the fluence at various positions even though the distributions are experimentally unknown. Finally, experimental fluences were obtained under the same conditions, and were compared with the simulation results.

To establish a methodology for neutron spectrum measurement at the CERN High energy AcceleRator Mixed field facility (CHARM), neutron spectra were measured using an NE213 scintillator on top of the CHARM roof shielding where is the CERN Shielding Benchmark Facility (CSBF). The spectra were derived as fluences into the scintillator by the unfolding method using an iterative Bayesian algorithm. The methodology was verified based on the agreement of two spectra measured for different positions and directions of incident neutrons by changing the detector orientation. Since the spectra on the roof-top were obtained within a reasonable beam-time, this methodology is suitable for measuring the spectrum when there is less shielding material. Thus, experimental data for neutron transition can be obtained as a function of shielding thickness using this facility.

The CERN High Energy AcceleRator Mixed field facility (CHARM) is located in the CERN Proton Synchrotron (PS) East Experimental Area. The facility receives a pulsed proton beam from the CERN PS with a beam momentum of 24 GeV/c with 5 ⋅ 10 11 protons per pulse with a pulse length of 350 ms and with a maximum average beam intensity of 6.7 ⋅ 10 10 p/s that then impacts on the CHARM target. The shielding of the CHARM facility also includes the CERN Shielding Benchmark Facility (CSBF) situated laterally above the target. This facility consists of 80 cm of cast iron and 360 cm of concrete with barite concrete in some places. Activation samples of bismuth and aluminium were placed in the CSBF and in the CHARM access corridor in July 2015. Monte Carlo simulations with the FLUKA code have been performed to estimate the specific production yields for these samples. The results estimated by FLUKA Monte Carlo simulations are compared to activation measurements of these samples. The comparison between FLUKA simulations and the measured values from γ -spectrometry gives an agreement better than a factor of 2.

In this study, experimental measurements were performed on the spectra of neutrons which penetrate concrete and steel of various thicknesses values when a proton beam of 24 GeV/c was incident on a copper target at the CHARM facility in the East Hall of the CERN Proton Synchrotron (PS) The thicknesses of concrete and steel ranged up to 360 cm and 80 cm, respectively. To measure the neutron spectra, an NE213 scintillator was positioned on the top roof of the shielding structure as the neutron detector. The light output distributions of the detector were converted into the neutron energy spectra using the unfolding method with a calculated response matrix after removing the γ -ray and charged particle events by pulse-shape discrimination and veto counter signals, respectively. The neutron spectra were in agreement with the results obtained using the Monte Carlo simulation code, PHITS, within a factor of 1.4 except for the case of steel 80 cm. The attenuation profiles for concrete and steel were consistent with previous foil activation results within the respective uncertainties.

The Review summarizes much of particle physics and cosmology. Using data from previous editions, plus 2,143 new measurements from 709 papers, we list, evaluate, and average measured properties of gauge bosons and the recently discovered Higgs boson, leptons, quarks, mesons, and baryons. We summarize searches for hypothetical particles such as supersymmetric particles, heavy bosons, axions, dark photons, etc. Particle properties and search limits are listed in Summary Tables. We give numerous tables, figures, formulae, and reviews of topics such as Higgs Boson Physics, Supersymmetry, Grand Unified Theories, Neutrino Mixing, Dark Energy, Dark Matter, Cosmology, Particle Detectors, Colliders, Probability and Statistics. Among the 120 reviews are many that are new or heavily revised, including a new review on Machine Learning, and one on Spectroscopy of Light Meson Resonances. The Review is divided into two volumes. Volume 1 includes the Summary Tables and 97 review articles. Volume 2 consists of the Particle Listings and contains also 23 reviews that address specific aspects of the data presented in the Listings. The complete Review (both volumes) is published online on the website of the Particle Data Group (pdg.lbl.gov) and in a journal. Volume 1 is available in print as the PDG Book. A Particle Physics Booklet with the Summary Tables and essential tables, figures, and equations from selected review articles is available in print, as a web version optimized for use on phones, and as an Android app., United States Department of Energy (DOE) DE-AC02-05CH11231, government of Japan (Ministry of Education, Culture, Sports, Science and Technology), Istituto Nazionale di Fisica Nucleare (INFN), Physical Society of Japan (JPS), European Laboratory for Particle Physics (CERN), United States Department of Energy (DOE)

The CERN High energy AcceleRator Mixed field (CHARM) facility is situated in the CERN Proton Synchrotron (PS) East Experimental Area. The facility receives a pulsed proton beam from the CERN PS with a beam momentum of 24 GeV/c with 5centerdot10¹¹ protons per pulse with a pulse length of 350 ms and with a maximum average beam intensity of 6.7centerdot10¹⁰ protons per second. The extracted proton beam impacts on a cylindrical copper target. The shielding of the CHARM facility includes the CERN Shielding Benchmark Facility (CSBF) situated laterally above the target that allows deep shielding penetration benchmark studies of various shielding materials. This facility has been significantly upgraded during the extended technical stop at the beginning of 2016. It consists now of 40 cm of cast iron shielding, a 200 cm long removable sample holder concrete block with 3 inserts for activation samples, a material test location that is used for the measurement of the attenuation length for different shielding materials as well as for sample activation at different thicknesses of the shielding materials. Activation samples of bismuth, aluminium and indium were placed in the CSBF in September 2016 to characterize the upgraded version of the CSBF. Monte Carlo simulations with the FLUKA code have been performed to estimate the specific production yields of bismuth isotopes (²⁰⁶ Bi, ²⁰⁵ Bi, ²⁰⁴ Bi, ²⁰³ Bi, ²⁰² Bi, ²⁰¹ Bi) from ²⁰⁹ Bi, ²⁴ Na from ²⁷ Al and ¹¹⁵ m I from ¹¹⁵ I for these samples. The production yields estimated by FLUKA Monte Carlo simulations are compared to the production yields obtained from γ-spectroscopy measurements of the samples taking the beam intensity profile into account. The agreement between FLUKA predictions and γ-spectroscopy measurements for the production yields is at a level of a factor of 2., 4th International Workshop on Accelerator Radiation Induced Activation (ARIA 2017), 22–24 May 2017, Lund, Sweden

The capabilities and physics models implemented inside the FLUKA code are briefly described, with emphasis on hadronic interaction. Examples of the performances of the code are presented including basic (thin target) and complex benchmarks, and radiation detector specific applications. In particular the ability of FLUKA in describing existing calorimeter performances and in predicting those of future ones, as well as the use of the code for neutron and mixed field radiation detectors will be demonstrated with several examples.

Radiation monitoring at high energy proton accelerators poses a considerable challenge due to the complexity of the encountered stray radiation fields. These environments comprise a wide variety of different particle types and span from fractions of electron-volts up to several terra electron-volts. As a consequence the use of Monte Carlo simulation programs like FLUKA is indispensable to obtain appropriate field-specific calibration factors. At many locations of the LHC a large contribution to the particle fluence is expected to originate from high-energy neutrons and thus, benchmark experiments with mono-energetic neutron beams are of high importance to verify the aforementioned detector response calculations. This paper summarizes the results of a series of benchmark experiments with quasi mono-energetic neutrons of 100, 140, 200, 250 and 392 MeV that have been carried out at RCNP - Osaka University, during several campaigns between 2006 and 2014.

Samples of copper, aluminium and stainless steel with well-characterized elemental compositions were irradiated in the stray radiation field created by a 2.5 GeV electron beam hitting a copper dump. After the irradiation the induced activity in the samples was analysed with gamma-ray spectrometry. The beam intensity monitoring with a current transformer was verified in an additional study by irradiating gold-foils stacked in between copper blocks and by analysing the production of Au for which detailed experimental cross section data exist. All results were finally compared to the predictions obtained with the FLUKA Monte-Carlo code. Excellent agreement between measurement and simulation within a few percent was obtained for the gold-foils irradiation confirming the accuracy of the beam monitoring. The benchmark of the FLUKA results with the data of the material samples showed good agreement, for many nuclides within 30%.

CERN, the European Organization for Nuclear Research, upgraded its operational dosimetry system in March 2013 to be prepared for the first Long Shutdown of CERN's facilities. The new system allows the immediate and automatic checking and recording of the dosimetry data before and after interventions in radiation areas. To facilitate the analysis of the data in context of CERN's approach to As Low As Reasonably Achievable (ALARA), this new system is interfaced to the Intervention Management Planning and Coordination Tool (IMPACT). IMPACT is a web-based application widely used in all CERN's accelerators and their associated technical infrastructures for the planning, the coordination and the approval of interventions (work permit principle). The coupling of the operational dosimetry database with the IMPACT repository allows a direct and almost immediate comparison of the actual dose with the estimations, in addition to enabling the configuration of alarm levels in the dosemeter in function of the intervention to be performed.

The FHT-762 WENDI-II is a commercially available wide range neutron rem counter which uses a 3 He counter tube inside a polyethylene moderator. To increase the response above 10 MeV of kinetic neutron energy, a layer of tungsten powder is implemented into the moderator shell. For the purpose of the characterization of the response, a detailed model of the detector was developed and implemented for FLUKA Monte Carlo simulations. In common practice Monte Carlo simulations are used to calculate the neutron fluence inside the active volume of the detector. The resulting fluence is then folded offline with the reaction rate of the 3 He(n,p) 3 H reaction to yield the proton–triton production rate. Consequently this approach does not consider geometrical effects like wall effects, where one or both reaction products leave the active volume of the detector without triggering a count. This work introduces a two-step simulation method which can be used to determine the detector's response, including geometrical effects, directly, using Monte Carlo simulations. A “first step” simulation identifies the 3 He(n,p) 3 H reaction inside the active volume of the 3 He counter tube and records its position. In the “second step” simulation the tritons and protons are started in accordance with the kinematics of the 3 He(n,p) 3 H reaction from the previously recorded positions and a correction factor for geometrical effects is determined. The three dimensional Monte Carlo model of the detector as well as the two-step simulation method were evaluated and tested in the well-defined fields of an 241 Am–Be(α,n) source as well as in the field of a 252 Cf source. Results were compared with measurements performed by Gutermuth et al. [1] at GSI with an 241 Am–Be(α,n) source as well as with measurements performed by the manufacturer in the field of a 252 Cf source. Both simulation results show very good agreement with the respective measurements. After validating the method, the response values in terms of counts per unit fluence were calculated for 95 different incident neutron energies between 1 meV and 5 GeV.

Particle accelerators and their surroundings are locations of residual radioactivity production that is induced by the interaction of high-energy particles with matter. This paper gives an overview of the principles of activation caused at proton accelerators, which are the main machines operated at Conseil Européen pour la Recherche Nucléaire. It describes the parameters defining radio-nuclide production caused by beam losses. The second part of the paper concentrates on the analytic calculation of activation and the Monte Carlo approach as it is implemented in the FLUKA code. Techniques used to obtain, on the one hand, estimates of radioactivity in Becquerel and, on the other hand, residual dose rates caused by the activated material are discussed. The last part of the paper focuses on experiments that allow for benchmarking FLUKA activation calculations and on simulations used to predict activation in and around high-energy proton machines. In that respect, the paper addresses the residual dose rate that will be induced by proton-proton collisions at an energy of two times 7 TeV in and around the Compact Muon Solenoid (CMS) detector. Besides activation of solid materials, the air activation expected in the CMS cavern caused by this beam operation is also discussed.

Samples of different solid materials as well as of water and soil were exposed to the stray radiation field created by a 28.5-GeV electron beam hitting a copper dump. After irradiation, specific activities and residual dose rates were measured at different cooling times from 1 h up to several months. Furthermore, the irradiation experiment was simulated with the FLUKA Monte Carlo code. The calculations included a detailed identification of interaction processes creating the different nuclides. First comparisons of experimental data on specific activities and FLUKA results indicate underestimation by FLUKA at irradiation locations laterally to the target, while the agreement seems reasonable downstream of it. The irradiation experiment, the current status of the data analysis, and a preliminary comparison with FLUKA results are presented.

In the framework of activation calculation of accelerator components with Monte Carlo methods, an unsolved problem is to take spallation products of trace elements and impurities in a bulk material into account. Due to the low probability of spallation reactions with these elements, a large number of primary particles are necessary to obtain some information about their spallation products, which is far from being converged. A new algorithm of treating high energy reactions has been implemented into MCNPX 2.5.0 to overcome these deficiencies. With this algorithm spallation reactions on all constituents of a material will be performed at each high energy interaction. This leads to the production of spallation products from all elements in a material. We will present examples on how this new methodology influences the outcome of activation calculations.

The FLUKA code is used to simulate the residual dose rates around a typical beam absorber considering various scenarios. The latter include carbon, copper, and tungsten as jaw materials, different beam energies, protons, and lead ion beams as well as different irradiation and cooling times. Using the dose rate maximum close to the absorber surface, the study investigates the cooling time dependence for the different scenarios. It is found to be similar for all jaw materials and beam energies. The dose rate scales with energy as E 0.83 and with the number of nucleons when comparing proton beam with lead ions. After a sufficiently long cooling time, a few radionuclides produced in the steel tank, such as 56 Co, 58 Co, 48 V, and 54 Mn, dominate the dose rate. The study can be easily extended to other materials or irradiation scenarios and can be applied to first evaluations of given accelerator design options.

Operating a high-energy accelerator like the Large Hadron Collider (LHC) requires a state-of-the-art monitoring system for radiation protection. In the vicinity of the accelerator as well as in the accessible areas behind thick shielding, a unique mixed radiation environment is encountered that consists of different particle types with energies ranging from fractions of electron volt up to several giga-electron-volts. Consequently, the correct assessment of ambient dose equivalent poses a challenging task and requires appropriate field-specific calibration methods, in particular as no adequate calibration sources exist. This circumstance motivated the development of a more accurate field calibration method for the LHC, based on benchmarked FLUKA Monte Carlo simulations. The method of obtaining such field calibration coefficients for IG5 high-pressure ionization chambers is exemplified in a case study for the LHCb experiment. Comparing these factors to calibration source―based values shows over- or underestimation of the actual dose by the source-based coefficient, depending on the location of the monitor.

In the course of the design of the CERN Large Hadron Collider collimation regions as well as of other locations where important beam losses are expected and that contain critical accelerator elements, the FLUKA Monte Carlo code is extensively used. The field of applications spans from energy deposition calculations, studies of material damage, and detector studies to shielding design and activation studies. Using the design of the passive absorbers as an example, this paper illustrates the simulation approach, defines involved critical quantities, and confronts the need for simplified and detailed simulations.

Radiation monitoring during operation of CERN’s high-energy accelerators in general, and the Large Hadron Collider and its experiments in particular, poses a major challenge due to the stray radiat...

Neutron energy spectra were measured behind the lateral shield of the CERF (CERN-EU High Energy Reference Field) facility at CERN with a 120 GeV/c positive hadron beam (a mixture of mainly protons and pions) on a cylindrical copper target (7-cm diameter by 50-cm long). An NE213 organic liquid scintillator (12.7-cm diameter by 12.7-cm long) was located at various longitudinal positions behind shields of 80- and 160-cm thick concrete and 40-cm thick iron. The measurement locations cover an angular range with respect to the beam axis between 13 and 133°. Neutron energy spectra in the energy range between 32 MeV and 380 MeV were obtained by unfolding the measured pulse height spectra with the detector response functions which have been verified in the neutron energy range up to 380 MeV in separate experiments. Since the source term and experimental geometry in this experiment are well characterized and simple and results are given in the form of energy spectra, these experimental results are very useful as benchmark data to check the accuracies of simulation codes and nuclear data. Monte Carlo simulations of the experimental set up were performed with the FLUKA, MARS and PHITS codes. Simulated spectra for the 80-cm thick concrete often agree within the experimental uncertainties. On the other hand, for the 160-cm thick concrete and iron shield differences are generally larger than the experimental uncertainties, yet within a factor of 2. Based on source term simulations, observed discrepancies among simulations of spectra outside the shield can be partially explained by differences in the high-energy hadron production in the copper target.

Radiation protection dosimetry in radiation fields behind the shielding of high-energy accelerators such as CERN is a challenging task and the quantitative understanding of the detector response used for dosimetry is essential. Measurements with ionisation chambers are a standard method to determine absorbed dose (in the detector material). For applications in mixed radiation fields, ionisation chambers are often also calibrated in terms of ambient dose equivalent at conventional reference radiation fields. The response of a given ionisation chamber to the various particle types of a complex high-energy radiation field in terms of ambient dose equivalent depends of course on the materials used for the construction and the chamber gas used. This paper will present results of computational studies simulating the exposure of high-pressure ionisation chambers filled with different types of gases to the radiation field at CERN's CERN-EU high-energy reference field facility. At this facility complex high-energy radiation fields, similar to those produced by cosmic rays at flight altitudes, are produced. The particle fluence and spectra calculated with FLUKA Monte Carlo simulations have been benchmarked in several measurements. The results can be used to optimise the response of ionisation chambers for the measurement of ambient dose equivalent in high-energy mixed radiation fields.

FLUKA is a Monte-Carlo code able to simulate interaction and transport of hadrons, heavy ions and electromagnetic particles from few keV (or thermal neutron) to cosmic ray energies in whichever material. The highest priority in the design and development of the code has always been the implementation and improvement of sound and modern physical models. A summary of the FLUKA physical models is given, while recent developments are described in detail: among the others, extensions of the intermediate energy hadronic interaction generator, refinements in photon cross sections and interaction models, analytical on-line evolution of radio-activation and remnant dose. In particular, new developments in the nucleus–nucleus interaction models are discussed. Comparisons with experimental data and examples of applications of relevance for space radiation are also provided.

2nd European Advanced Accelerator Concepts Workshop, EAAC2015, La Biodola, Isola d'Elba, Italy, 13 Sep 2015 - 19 Sep 2015 ; Nuclear instruments & methods in physics research / A 829, 3 - 16(2016). doi:10.1016/j.nima.2015.12.050, This paper describes the conceptual steps in reaching the design of the AWAKE experiment currently under construction at CERN. We start with an introduction to plasma wakefield acceleration and the motivation for using proton drivers. We then describe the self-modulation instability – a key to an early realization of the concept. This is then followed by the historical development of the experimental design, where the critical issues that arose and their solutions are described. We conclude with the design of the experiment as it is being realized at CERN and some words on the future outlook. A summary of the AWAKE design and construction status as presented in this conference is given in Gschwendtner et al., Published by North-Holland Publ. Co., Amsterdam

The European Laboratory for Particle Physics (CERN) has been operating accelerators for high-energy physics both on Swiss and French territory for over 50 years. Due to the interaction of the particle beams with matter, the accelerator components and the surroundings become activated and shall be treated as radioactive waste once the end of their operational lifetime is reached. For disposal towards the final repositories the radioactive waste legislation of both CERN Host-States requires the knowledge of the radionuclide inventory. This paper discusses the studies that are carried out at CERN for the characterization of the metallic radioactive waste produced every year in the several high-energy accelerators. The radionuclide inventory as well as the specific activity of radioactive waste originating from accelerators varies depending on the accelerated beam, on the location of the material with respect to the beam losses and the decay time already elapsed. The approach proposed at CERN is based on an estimate of the specific activity per radionuclide with the Monte-Carlo code FLUKA, by simulating the radiation environment to which the radioactive waste was exposed during its operational lifetime. This method has been validated for the CERN ISOLDE facility by both γ-spectrometry and Monte-Carlo simulation of the target. The use of this method in those cases where the irradiation conditions are not known with sufficient precision requires careful extrapolation based on additional dose-rate and gamma-spectrometry measurements.

Samples of different materials, consisting of major elements with masses up to the one of copper, were exposed to the stray radiation field created by a 120 GeV hadron beam in a copper target. The induced specific activities of radionuclides, as measured with gamma spectrometry, then served as benchmark of the FLUKA Monte Carlo code. A careful analysis of the experimental data as well as of the reactions leading to the various isotopes in the simulation demonstrated that FLUKA is capable of predicting individual isotopes with an uncertainty of less than 20–30% in most cases. Due to the universal nature of the high energy interaction models the results also serve as indirect validation of FLUKA predictions for target materials, reactions and isotopes not covered by this study.

The management of activated water in the Large Hadron Collider (LHC) at CERN is a key concern for radiation protection. For this reason, the induced radioactivity of the different water circuits is calculated using the Monte-Carlo (MC) code FLUKA. The results lead to the definition of procedures to be taken into account during the repair and maintenance of the machine, as well as to measures being necessary for a release of water into the environment. In order to assess the validity of the applied methods, a benchmark experiment was carried out at the CERN-EU High Energy Reference Field (CERF) facility, where a hadron beam (120 GeV) is impinging on a copper target. Four samples of water, as used at the LHC, and different in their chemical compositions, were irradiated near the copper target. In addition to the tritium activity measured with a liquid scintillation counter, the samples were also analyzed using gamma spectroscopy in order to determine the activity of the gamma emitting isotopes such as Be 7 and Na 24 . While for the latter an excellent agreement between simulation and measurement was found, for the calculation of tritium a correction factor is derived to be applied for future LHC calculations in which the activity is calculated by direct scoring of produced nuclei. A simplified geometry representing the LHC Arc sections is then used to evaluate the different calculation methods with FLUKA. By comparing these methods and by taking into account the benchmark results, a strategy for the environmental calculations can be defined.

Neutron energy spectra were measured behind the lateral shield of the CERF (CERN-EU High Energy Reference Field) facility at CERN with a 120 GeV/c positive hadron beam (mainly a mixture of protons and pions) on a cylindrical copper target (7-cm diameter by 50-cm long). NE213 organic liquid scintillator (12.7-cm diameter by 12.7-cm long) was located at various longitudinal positions behind shields of 80- and 160-cm thick concrete and 40-cm thick iron. Neutron energy spectra in the energy range between 12 MeV and 380 MeV were obtained by unfolding the measured pulse height spectra with the detector response functions which have been experimentally verified in the neutron energy range up to 380 MeV in separate experiments. The corresponding MARS15 Monte Carlo simulations generally gave good agreements with the experimental energy spectra. © 2001 Elsevier Science. All rights reserved

The LHC will require an extremely powerful and unprecedented collimation system. As approximately 30% of the LHC beam is lost in the cleaning insertions, these will become some of the most radioactive locations around the entire LHC ring. Thus, remanent dose rates to be expected during later repair or maintenance interventions must be considered in the design phase itself. As a consequence, the beam cleaning insertions form a unique test bed for a recently developed approach to calculate remanent dose rates. A set of simulations, different in complexity, is used in order to evaluate methods for the estimation of remanent dose rates. The scope, as well as the restrictions, of the omega-factor method are shown and compared with the explicit simulation approach. The latter is then used to calculate remanent dose rates in the beam cleaning insertions. Furthermore, a detailed example for maintenance dose planning is given.

A new method to estimate remanent dose rates, to be used with the Monte Carlo code FLUKA, was benchmarked against measurements from an experiment that was performed at the CERN-EU high-energy reference field facility. An extensive collection of samples of different materials were placed downstream of, and laterally to, a copper target, intercepting a positively charged mixed hadron beam with a momentum of 120 GeV c(-1). Emphasis was put on the reduction of uncertainties by taking measures such as careful monitoring of the irradiation parameters, using different instruments to measure dose rates, adopting detailed elemental analyses of the irradiated materials and making detailed simulations of the irradiation experiment. The measured and calculated dose rates are in good agreement.

Samples of materials which will be used in the LHC machine for shielding and construction components were irradiated in the stray radiation field of the CERN-EU high-energy reference field facility. After irradiation, the specific activities induced in the various samples were analysed with a high-precision gamma spectrometer at various cooling times, allowing identification of isotopes with a wide range of half-lives. Furthermore, the irradiation experiment was simulated in detail with the FLUKA Monte Carlo code. A comparison of measured and calculated specific activities shows good agreement, supporting the use of FLUKA for estimating the level of induced activity in the LHC.

The FLUKA Monte Carlo transport code is widely used for fundamental research, radioprotection and dosimetry, hybrid nuclear energy system and cosmic ray calculations. The validity of its physical models has been benchmarked against a variety of experimental data over a wide range of energies, ranging from accelerator data to cosmic ray showers in the earth atmosphere. The code is presently undergoing several developments in order to better fit the needs of space applications. The generation of particle spectra according to up-to-date cosmic ray data as well as the effect of the solar and geomagnetic modulation have been implemented and already successfully applied to a variety of problems. The implementation of suitable models for heavy ion nuclear interactions has reached an operational stage. At medium/high energy FLUKA is using the DPMJET model. The major task of incorporating heavy ion interactions from a few GeV/n down to the threshold for inelastic collisions is also progressing and promising results have been obtained using a modified version of the RQMD-2.4 code. This interim solution is now fully operational, while waiting for the development of new models based on the FLUKA hadron-nucleus interaction code, a newly developed QMD code, and the implementation of the Boltzmann master equation theory for low energy ion interactions. c2004 COSPAR. Published by Elsevier Ltd. All rights reserved.

Energy spectra of high-energy neutrons and neutron time-of-flight spectra were calculated for the setup of experiment T-454 performed with a NE213 liquid scintillator at the Final Focus Test Beam (FFTB) facility at the Stanford Linear Accelerator Center. The neutrons were created by the interaction a 28.7 GeV electron beam in the aluminum beam dump of the FFTB which is housed inside a thick steel and concrete shielding. In order to determine the attenuation length of high-energy neutrons additional concrete shielding of various thicknesses was placed outside the existing shielding. The calculations were performed using the FLUKA interaction and transport code. The energy and time-of-flight were recorded for the location of the detector allowing a detailed comparison with the experimental data. A generally good description of the data is achieved adding confidence to the use of FLUKA for the design of shielding for high-energy electron accelerators.

Neutron energy and time-of-flight spectra were measured behind the lateral shield of the electron beam dump at the Final Focus Test Beam (FFTB) facility at the Stanford Linear Accelerator Center. The neutrons were produced by a 28.7 GeV electron beam hitting the aluminum beam dump of the FFTB which is housed inside a thick steel and concrete shield. The measurements were performed using a NE213 organic liquid scintillator behind different thicknesses of the concrete shield of 274 cm, 335 cm, and 396 cm, respectively. The neutron energy spectra between 6 and 800 MeV were obtained by unfolding the measured pulse height spectrum with the detector response function. The attenuation length of neutrons in concrete was then derived. The spectra of neutron time-of-flight between beam on dump and neutron detection by NE213 were also measured. The corresponding experimental results were simulated with the FLUKA Monte Carlo code. The experimental results show good agreement with the simulated results.

The capabilities and physics model implemented inside the FLUKA code are briefly described, with emphasis on hadronic interaction. Examples of the performances of the code are presented including basic (thin target) and complex benchmarks, and radiation detector specific applications. In particular the ability of FLUKA in describing existing calorimeter performances and in predicting those of future ones, as well as the use of the code for neutron and mixed field radiation detectors will be demonstrated with several examples.

The implementation of three-dimensional geometries for the simulation of radiation transport problems is a very time-consuming task. Each particle transport code supplies its own scripting language and syntax for creating the geometries. All of them are based on the Constructive Solid Geometry scheme requiring textual description. This makes the creation a tedious and error-prone task, which is especially hard to master for novice users. The Monte Carlo code FLUKA comes with built-in support for creating two-dimensional cross-sections through the geometry and FLUKACAD, a custom-built converter to the commercial Computer Aided Design package AutoCAD, exists for 3D visualization. For other codes, like MCNPX, a couple of different tools are available, but they are often specifically tailored to the particle transport code and its approach used for implementing geometries. Complex constructive solid modeling usually requires very fast and expensive special purpose hardware, which is not widely available. In this paper SimpleGeo is presented, which is an implementation of a generic versatile interactive geometry modeler using off-the-shelf hardware. It is running on Windows, with a Linux version currently under preparation. This paper describes its functionality, which allows for rapid interactive visualization as well as generation of three-dimensional geometries, and also discusses critical issues regarding common CAD systems.

The multi-purpose particle interaction and transport code FLUKA is integral part of all radiation protection studies for the design and operation of the Large Hadron Collider (LHC) at CERN. It is one of the very few codes available for this type of calculations which is capable to calculate in one and the same simulation proton-proton and heavy ion collisions at LHC energies as well as the entire hadronic and electromagnetic particle cascade initiated by secondary particles in detectors and beam-line components from TeV energies down to energies of thermal neutrons. The present paper reviews these capabilities of FLUKA in giving details of relevant physics models along with examples of radiation protection studies for the LHC such as shielding studies for underground areas occupied by personnel during LHC operation and the simulation of induced radioactivity around beam loss points. Integral part of the FLUKA development is a careful benchmarking of specific models as well as the code performance in complex, real life applications which is demonstrated with examples of studies relevant to radiation protection at the LHC.

FLUKA is a general purpose Monte Carlo code capable of handling all radiation components from thermal energies (for neutrons) or 1 keV (for all other particles) to cosmic ray energies and can be applied in many different fields. Presently the code is maintained on Linux. The validity of the physical models implemented in FLUKA has been benchmarked against a variety of experimental data over a wide energy range, from accelerator data to cosmic ray showers in the Earth atmosphere. FLUKA is widely used for studies related both to basic research and to applications in particle accelerators, radiation protection and dosimetry, including the specific issue of radiation damage in space missions, radiobiology (including radiotherapy) and cosmic ray calculations. After a short description of the main features that make FLUKA valuable for these topics, the present paper summarizes some of the recent applications of the FLUKA Monte Carlo code in the nuclear as well high energy physics. In particular it addresses such topics as accelerator related applications.

The assessment of radiation damage to electronics is a complex process and requires a detailed description of the full particle energy spectra, as well as a clear characterization of the quantities used to predict radiation damage. FLUKA, a multi-purpose particle interaction and transport code, is capable of calculating proton-proton and heavy ion collisions at LHC energies and beyond. It correctly describes the entire hadronic and electromagnetic particle cascade initiated by secondary particles from TeV energies down to thermal neutrons, and provides direct scoring capabilities essential to estimate in detail the possible risk of radiation damage to electronics. This paper presents the FLUKA capabilities for applications related to radiation damage to electronics, providing benchmarking examples and showing the practical applications of FLUKA at CERN facilities such as CNGS and LHC. Related applications range from the study of device effects, the detailed characterization of the radiation field and radiation monitor calibration, to the input requirements for important mitigation studies including shielding, relocation or other options.

A Cerium Fluoride crystal produced during early R&D studies for calorimetry at the CERN Large Hadron Collider was exposed to a 24 GeV/c proton fluence Phi_p=(2.78 +- 0.20) x 10EE13 cm-2 and, after one year of measurements tracking its recovery, to a fluence Phi_p=(2.12 +- 0.15) x 10EE14 cm-2. Results on proton-induced damage to the crystal and its spontaneous recovery after both irradiations are presented here, along with some new, complementary data on proton-damage in Lead Tungstate. A comparison with FLUKA Monte Carlo simulation results is performed and a qualitative understanding of high-energy damage mechanism is attempted., Submitted to Elsevier Science on May 6th, 2010; 11 pages, 8 figures

To understand baryon stopping we analyse new RHIC and Fermilab data within the framework of the multichain Monte Carlo DPMJET-III. The present consideration is restricted to to hadron-hadron and d-Au collisions., 10 pages, 19 figures. The paper is expanded in a mayor way to include more data

The monitoring of ambient doses at work places around high-energy accelerators is a challenging task due the complexity of the mixed stray radiation fields encountered. At CERN, mainly Centronics IG5 high-pressure ionisation chambers are used to monitor radiation exposure in mixed fields. The monitors are calibrated in the operational quantity ambient dose equivalent H*(10) using standard, source-generated photon- and neutron fields. However, the relationship between ionisation chamber reading and ambient dose equivalent in a mixed high-energy radiation field can only be assessed if the spectral response to every component and the field composition is known. Therefore, comprehensive studies were performed at the CERN-EU high-energy reference field facility where the spectral fluence for each particle type has been assessed with Monte Carlo simulations. Moreover, studies have been performed in an accessible controlled radiation area in the vicinity of a beam loss point of CERN's proton synchrotron. The comparison of measurements and calculations has shown reasonable agreement for most exposure conditions. The results indicate that conventionally calibrated ionisation chambers can give satisfactory response in terms of ambient dose equivalent in stray radiation fields at high-energy accelerators in many cases. These studies are one step towards establishing a method of ‘field calibration’ of radiation protection instruments in which Monte Carlo simulations will be used to establish a correct correlation between the response of specific detectors to a given high-energy radiation field.