SHADOWS [1, 2] is an intended future beam dump experiment in the CERN North Area, aiming to search for feebly interacting particles (FIPs) [3] created in 400 GeV/c proton interactions. Due to its proposed off-axis location alongside the K12 beamline [4], the SHADOWS detector can be placed potentially very close to the beam dump, enabling it to search for FIPs in unexplored parts of the parameter space. In order to guarantee good quality of a potential signal, it is crucial to reduce any backgrounds of Standard Model particles as much as possible. The dominant background downstream the beam dump is caused by muons [1]. This introduces the need of a dedicated muon sweeping system consisting of magnetised iron blocks (MIBs) to actively mitigate this background component. We present the conceptional design studies in the framework of the Conventional Beams Working Group of the Physics Beyond Colliders Initiative at CERN [5, 6].

Creating and maintaining computer readable geometries for use in Monte Carlo Radiation Transport (MCRT) simulations is an error-prone and time-consuming task. Simulating a system often requires geometry from different sources and modelling environments, including a range of MCRT codes and computer-aided design (CAD) tools. PYG4OMETRY is a Python library that enables users to rapidly create, manipulate, display, read and write Geometry Description Markup Language (GDML)-based geometry used in simulations. PYG4OMETRY provides importation of CAD files to GDML tessellated solids, conversion of GDML geometry to FLUKA and conversely from FLUKA to GDML. The implementation of PYG4OMETRY is explained in detail along with small examples. The paper concludes with a complete example using most of the PYG4OMETRY features and a discussion of extensions and future work.

Due to the advancement of proton therapy for cancer treatment, there has been a worldwide increase in the construction of treatment facilities. Therapy centres are often coupled with clinical, biological or material-science research programs. Research activities require proton beams at energies spanning an extensive range with higher beam currents and longer irradiation times than clinical conditions. Additionally, next-generation proton therapy systems are evolving towards more compact designs. In addition to the increased centres’ workloads, reducing the system in size produces a more significant number of secondary particles per unit volume and time. Therefore, the activation level of materials constituting those future proton therapy centres is expected to be higher, increasing the ambient dose and the amount of radioactive waste collected at the end of a centre’s lifetime. These operating conditions pose new challenges for the shielding design and the reduction of the concrete activation. To tackle them, we propose a novel approach to seamlessly simulate all the processes relevant for the evaluation of the concrete shielding activation using, as an illustration, the Ion Beam Applications Proteus $$^\circledR $$ One system. A realistic model of the system is developed using Beam Delivery Simulation (BDSIM), a Geant4-based particle tracking code. It allows a single model to simulate primary and secondary particle tracking in the beamline, its surroundings, and all particle-matter interactions. The code system and library database FISPACT-II allows the computation of the shielding activation by solving the rate equations using ENDF-compliant group library data for nuclear reactions, particle-induced or spontaneous fission yields, and radioactive decay. As input, FISPACT-II is provided with the secondary particle fluences scored using the BDSIM Monte Carlo simulations. This approach is applied to the proton therapy research centre of Charleroi, Belgium. Results compare the evolution of the clearance level and the long-lived nuclide concentrations throughout the facility lifetime when using regular concrete or the newly developed Low Activation Concrete (LAC). A comparison with the initial shielding dimensioning has been performed for all the shielding walls to validate the methodology and highlight the clear benefits of integrating LAC inserts in the shielding design. The effectiveness of coupling BDSIM and FISPACT-II gives a glimpse of the possibility of a complete activation study following the actual workloads of the centre, allowing a better assessment of the shielding activation level at any time of the facility lifespan.

Beam Delivery Simulation (BDSIM) is a program that simulates the passage of particles in a particle accelerator. It uses a suite of standard high energy physics codes (Geant4, ROOT and CLHEP) to create a computational model of a particle accelerator that combines accurate accelerator tracking routines with all of the physics processes of particles in Geant4. This unique combination permits radiation and detector background simulations in accelerators where both accurate tracking of all particles is required over long range or over many revolutions of a circular machine, as well as interaction with the material of the accelerator.

Hadron therapy installations are evolving towards more compact systems that require higher-quality beams for advanced treatment modalities such as proton flash and arc therapy. Therefore the accurate modelling of present and next-generation systems poses new challenges where the simulations require both magnetic beam transport and particle-matter interactions. We present a novel approach to building simulations of beam delivery systems at a level suitable for clinical applications while seamlessly providing the computation of quantities relevant for beam dose deposition, radiation protection assessment, and shielding activation determination. A realistic model of the Ion Beam Applications (IBA) Proteus® One system is developed using Beam Delivery Simulation (BDSIM), based on Geant4, that uniquely allows simulation using a single model. Its validation against measured data is discussed in detail. The first results of self-consistent simulations for beam delivery and equivalent ambient dose are presented. The results show that our approach successfully models the complex interactions between the beam transport and its interactions with the system for relevant clinical scenarios at an acceptable computational cost.

BDSIM is a program that uses a suite of high energy physics software including Geant4, CLHEP & ROOT, to seamlessly track particles through a 3dimensional accelerator model utilising the full range of particles and physics processes from Geant4. BDSIM was originally developed to simulate linear colliders such as the International Linear Collider (ILC), but has more recently been extended for application to the Large Hadron Collider (LHC), and generally to storage rings. The significant modernisation and revision of the implementation undertaken from 2013 to facilitate these simulations is presented here along with an example of the capabilities.

The Centre for the Clinical Application of Particles' Laser-hybrid Accelerator for Radiobiological Applications (LhARA) facility is being studied and requires simulation of novel accelerator components (such as the Gabor lens capture system), detector simulation and simulation of the ion beam interaction with cells. The first stage of LhARA will provide protons up to 15 MeV for in vitro studies. The second stage of LhARA will use a fixed-field accelerator to increase the energy of the particles to allow in vivo studies with protons and in vitro studies with heavier ions. BDSIM, a Geant4 based accelerator simulation tool, has been used to perform particle tracking simulations to verify the beam optics design done by BeamOptics and these show good agreement. Design parameters were defined based on an EPOCH simulation of the laser source and a series of mono-energetic input beams were generated from this by BDSIM. The tracking results show the large angular spread of the input beam (0.2 rad) can be transported with a transmission of almost 100% whilst keeping divergence at the end station very low (<0.1 mrad). The legacy of LhARA will be the demonstration of technologies that could drive a step-change in the provision of proton and light ion therapy (i.e. a laser source coupled to a Gabor lens capture and a fixed-field accelerator), and a system capable of delivering a comprehensive set of experimental data that can be used to enhance the clinical application of proton and light ion therapy.

CERN has a unique set of secondary beam lines, which deliver particles extracted from the PS and SPS accelerators after their interaction with a target material reaching energies up to 400 GeV. These beam lines provide a crucial contribution for test beam facilities, and host several fixed target experiments. A correct operation of the beam lines requires precise simulations of the beam optics and studies on the beam-matter interaction, radiation protection, beam equipment survival etc. BDSIM combines tracking studies with energy deposition and beam-matter interaction simulations within one software framework. This paper presents studies conducted on secondary beam lines with BDSIM for the beam lines T9 and T10. We report the tracking analysis and the energy deposition along the beam line. Tracking analysis validation is demonstrated via comparison to existing tracking codes.

The Compact Linear Collider (CLIC) is a TeV-scale high-luminosity linear $e^+e^-$ collider under development at CERN. Following the CLIC conceptual design published in 2012, this report provides an overview of the CLIC project, its current status, and future developments. It presents the CLIC physics potential and reports on design, technology, and implementation aspects of the accelerator and the detector. CLIC is foreseen to be built and operated in stages, at centre-of-mass energies of 380 GeV, 1.5 TeV and 3 TeV, respectively. CLIC uses a two-beam acceleration scheme, in which 12 GHz accelerating structures are powered via a high-current drive beam. For the first stage, an alternative with X-band klystron powering is also considered. CLIC accelerator optimisation, technical developments and system tests have resulted in an increased energy efficiency (power around 170 MW) for the 380 GeV stage, together with a reduced cost estimate at the level of 6 billion CHF. The detector concept has been refined using improved software tools. Significant progress has been made on detector technology developments for the tracking and calorimetry systems. A wide range of CLIC physics studies has been conducted, both through full detector simulations and parametric studies, together providing a broad overview of the CLIC physics potential. Each of the three energy stages adds cornerstones of the full CLIC physics programme, such as Higgs width and couplings, top-quark properties, Higgs self-coupling, direct searches, and many precision electroweak measurements. The interpretation of the combined results gives crucial and accurate insight into new physics, largely complementary to LHC and HL-LHC. The construction of the first CLIC energy stage could start by 2026. First beams would be available by 2035, marking the beginning of a broad CLIC physics programme spanning 25-30 years.

To fully understand the beam losses, subsequent radiation, energy deposition, backgrounds and activation in particle accelerators, a holistic approach combining a 3-D model, physics processes and accelerator tracking is required. Beam Delivery Simulation (BDSIM) is a program developed to simulate the passage of particles, both primary and secondary, in particle accelerators and calculate the energy deposited by these particles via material interactions using the Geant4 physics library. A Geant4 accelerator model is built from an optical description of a lattice by procedurally placing a set of predefined accelerator components. These generic components can be refined to an arbitrary degree of detail with the use of user-defined geometries, detectors, field maps, and more. A detailed model of the Large Hadron Collider has been created in BDSIM, validated with existing tracking codes and applied to study beam loss patterns.

Diamond Light source is a third generation synchrotron facility dedicated to producing radiation of outstanding brightness, ranging from infra-red to x-rays. The short electron bunches that are accelerated around the storage ring are susceptible to the phenomenon of microbunching instabilities when the bunch charge exceeds a threshold. The primary feature of the microbunch instabilities is the onset of bursts of radiation in the THz range. The high frequencies involved in the emissions make detection and analysis challenging. A 60-90 GHz Schottky Barrier Diode detector was installed to investigate turn by turn evolution of the instabilities.

Objective: To determine the roles of immediate pars plana vitrectomy (VIT) and systemic antibiotic treatment in the management of postoperative endophthalmitis.Design: Investigator-initiated, multicenter, randomized clinical trial.Setting: Private and university-based retina-vitreous practices.Patients: A total of 420 patients who had clinical evidence of endophthalmitis within 6 weeks after cataract surgery or secondary intraocular lens implantation.Interventions: Random assignment according to a 2 X 2 factorial design to treatment with VIT or vitreous tap or biopsy (TAP) and to treatment with or without systemic antibiotics (ceftazidime and amikacin).Main Outcome Measures: A 9-month evaluation of visual acuity assessed by an Early Treatment Diabetic Retinopathy Study acuity chart and media clarity assessed both clinically and photographically.Results: There was no difference in final visual acuity or media clarity with or without the use of systemic antibiotics. In patients whose initial visual acuity was hand motions or better, there was no difference in visual outcome whether or not an immediate VIT was performed. However, in the subgroup of patients with initial light perception-only vision, VIT produced a threefold increase in the frequency of achieving 20/40 or better acuity (33% vs 11%), approximately a twofold chance of achieving 20/100 or better acuity (56% vs 30%), and a 50% decrease in the frequency of severe visual loss (20% vs 47%) over TAP. In this group of patients, the difference between VIT and TAP was statistically significant (P < .001, log rank test for cumulative visual acuity scores) over the entire range of vision.Conclusions: Omission of systemic antibiotic treatment can reduce toxic effects, costs, and length of hospital stay. Routine immediate VIT is nor necessary in patients with better than light perception vision at presentation but is of substantial benefit for those who have light perception-only vision.