[en] A simulation study is presented of the shielding requirements around the inner triplets of the two high-luminosity pp-experiments (ATLAS and CMS) at the LHC. It is shown that concrete walls of 5 m thickness are needed in order to provide enough attenuation so that dose rates in occupied areas behind this shield would not exceed the design limit of 10 μSv/h. This requirement is more stringent than the thickness of 4 m required at any point around the ring to shield against full beam losses. (author)

[en] This paper describes an investigation into whether estimates of attenuation in the flat sidewalls of the tunnel for the MC main ring can be based on a simple point-source/line-of-sight model. Having seen the limitations of such a model, an alternative is proposed where the main radiation source is not the initial object struck by the beam but the plane source provided by the first interactions of secondaries from the target in the shield-wall. This is shown to have a closer relation to reality than the point-source/line-of-sight model. (author)

[en] Simulation studies of Non-Ionising Energy Loss (NIEL) in silicon exposed to various types of hadron irradiation are presented. A simulation model of migration and clustering of the produced primary defects is developed. Although there are many uncertainties in the input parameters it is shown that the model is consistent with experimental observations on standard and oxygen-enriched silicon. However, the model makes the rather dramatic prediction that NIEL scaling of leakage current and effective doping concentration can be violated significantly even in standard silicon. Although there are possible shortcomings in the model which might account for this, it is shown that at the microscopic level there is, indeed, no obvious reason for an exact NIEL scaling. Furthermore, it is argued that, contrary to common belief, even a significant violation of NIEL scaling can still be consistent with experimental data

[en] We present a new method to estimate Single Event Upsets (SEU) in a hadron accelerator environment, which is characterized by a complicated radiation spectrum. Our method is based on first principles, i.e. an explicit generation and transport of nuclear fragments and detailed accounting for energy loss by ionization. However, instead of simulating also the behaviour of the circuit, we use a Weibull fit to experimental heavy-ion SEU data in order to quantify the SEU sensitivity of the circuit. Thus, in principle, we do not need to know details about the circuit and our method is almost free of adjustable parameters - we only need a reasonable guess for the Sensitive Volume (SV) size. We show by a comparison with experimental data that our method predicts the SEU cross sections for protons rather accurately. We then indicate with an example how our method could be applied to predict SEU rates at the forthcoming LHC experiments

[en] This paper describes studies of the attenuation in a concrete shielding wall between the LHC-B detector and its counting room in the existing cavern at Point 8 of LHC with a full Monte-Carlo simulation using the FLUKA code. The calculated dose equivalent distributions for a possible shielding wall configuration, which fulfills practical requirements for the shield design in the limited space, are presented. It is also shown that there is no significant leakage of stray radiation through the vertical shaft to the surface of the earth in the simulation. (author)

[en] This paper describes the production of induced radioactivity in samples of aluminium, iron and copper exposed to high-energy hadronic radiation. The samples were irradiated in a stray radiation field generated by the interaction of 24 GeV/c protons in the beam dump of the PS IRRAD2 facility ai CERN. The specific radioactivity induced in the samples was measured by gamma spectrometry. The Monte Carlo particle transport code FLUKA was used to simulate the irradiation experiment in order to predict the production of radioactive isotopes in the samples. These predictions are compared with the experimental measurements. (author)

[en] Several examples will be given which illustrate the special features of the Monte-Carlo cascade simulation program FLUKA, used in the verification studies of shielding for the LHC. These include the use of different estimators for dose equivalent, region importance weighting with particle splitting, Russian Roulette and weight windows both at region boundaries and m secondary production at inelastic reactions and decay-length biasing in order to favour secondary particle production. (author)

[en] This article presents the radiological aspects taken into account in the construction of the LHC (Large Hadron Collider at CERN). This Accelerator will be installed in the 27 km circumference tunnel of the existing LEP (Large Electron Positron collider). The high-intensity of the circulating beams (each beam contains more than 10¹⁴ protons with an energy of 7 TeV) determines the thickness of the shielding for the main tunnel and the measures to be considered in the design of the beam absorption blocks, as well as the induced radioactivity due to the loss of protons in the main ring by inelastic scattering with residual gas in the vacuum chamber. The maximum luminosity of the collider will be 10⁹ inelastic interactions per second in each of the two main experimental devices, ATLAS and CMS. These interactions determine the shielding of the experimental zones, the induced radioactivity both in the detectors and accelerator components situated on each side of the experimental zones and, to a certain degree, the radioactivity induced in the beam collimating regions. The major environmental issues are also presented

[en] Fast wire scanners are today considered as part of standard instrumentation in high energy synchrotrons. The extension of their use to synchrotrons working at lower energies, where Coulomb scattering can be important and the transverse beam size is large, introduces new complications considering beam heating of the wire, composition of the secondary particle shower and geometrical consideration in the detection set-up. A major problem in treating these effects is that the creation of secondaries in a thin carbon wire by a energetic primary beam is difficult to describe in an analytical way. We here present new results from a full Monte Carlo simulation of this process yielding information on heat deposited in the wire, particle type and energy spectrum of secondaries and angular dependence as a function of primary beam energy. The results are used to derive limits for the use of wire scanners in low energy accelerators. (orig.)

[en] The geometry and transparency of the beam pipe is expected to be reflected in the radiation background at the LHC experiments. We compare the neutron background produced by four different beam pipe geometries. As a result of our simulation studies, we argue that a pointing conical beam pipe is an attractive choice to minimize neutron backgrounds in experiments. This fact remains true even when the horizontal vertex source distribution and the presence of a strong magnetic field are included. ((orig.))