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The Large Hadron Collider (LHC) at the European Organization for Nuclear Research (CERN) is the world’s largest and most powerful particle accelerator colliding beams of protons and lead ions at energies up to 7 TeV and 2.76 TeV, respectively. ALICE is one of the detector experiments optimised for heavy-ion collisions. A fixed-target experiment in ALICE is considered to collide a portion of the beam halo, split using a bent crystal, with an internal target placed a few meters upstream of the detector. Fixed-target collisions offer many physics opportunities related to hadronic matter and the quark-gluon plasma to extend the research potential of the CERN accelerator complex. Production of physics events depends on the particle flux on target. The machine layout for the fixed-target experiment is being developed to provide a flux of particles on a target high enough to exploit the full capabilities of the ALICE detector acquisition system. In this paper, we discuss a method of increasing the system’s performance by applying a local modification of optics to set the crystal at the optimal betatron phase., Proceedings of the 13th International Particle Accelerator Conference, IPAC2022, Bangkok, Thailand

The High Intensity Muon Beams (HIMB) project at the Paul Scherrer Institute (PSI) will provide muon intensities of the order of 1e10 muons/s for particle physics and material science experiments, two orders of magnitude higher than the state of the art, which is currently available also at PSI. In particle transport simulations for the HIMB, we use G4beamline with measured pi+ cross-sections and with variance reduction. We also use the codes COSY INFINITY, TRANSPORT, and TURTLE for some studies. We perform asynchronous Bayesian optimisation of the beamlines on a computing cluster using G4beamline and the optimisation package DeepHyper. We performed numerous studies for the design of the HIMB, and we produced various results, including the muon transmission, beam phase space, polarisation, and momentum spectrum., Proceedings of the 13th International Particle Accelerator Conference, IPAC2022, Bangkok, Thailand

A Physics Beyond Colliders (PBC) initiative was recently established at CERN to exploit the full scientific potential of its accelerator complex and scientific infrastructure to tackle fundamental open questions in particle physics through experiments complementary to those in current and future colliders. This initiative brings together similar studies to optimize resources globally in order to reach a common goal and promote scientific development efficiently. In this work, we present the work performed by the Conventional Beam Working Group (CBWG) and specifically from the Neutrino Beams (NB) subgroup. The subgroup currently deals with two novel neutrino-tagged beams projects, ENUBET and NUTAG, as well as with a more classic, low energy, beamline dedicated to hadron cross-sections for neutrino beams with the NA61 experiment already installed in the H₂ beamline of the CERN North Area. This contribution will detail the advances made with these three projects as well as their status and future plans., Proceedings of the 13th International Particle Accelerator Conference, IPAC2022, Bangkok, Thailand

Modern particle accelerator projects, such as MYRRHA, have very high stability and/or reliability requirements. To meet those, it is necessary to optimize or develop new methods for the control systems. One of the difficulties lies in the relatively long computation time of current beam dynamics codes. In this context, the very low computation time of neural network is of great attraction. However, a neural network has to be trained in order to be of any use. The training of a beam dynamic predictor uses a large dataset (experimental or simulated) that represents the dynamics over the parameter space of interest. Therefore, choosing the right training dataset is crucial for the quality of the neural network predictions. In this work, a study on the sampling choice for the training data is performed to train a neural network to predict the transmission of a beam through a low energy beam transport line and a Radiofrequency Quadrupole. We show and discuss the results obtained on training data set to model the IPHI and MYRRHA injectors., Proceedings of the 10th Int. Particle Accelerator Conf., IPAC2019, Melbourne, Australia

Dark current is particularly relevant during operation in high-gradient linear accelerators. Resulting from the capture of field emitted electrons, dark current produces additional radiation that needs to be accounted for in experiments. In this paper, an analysis of dark current is presented for four accelerating structures that were tested and conditioned in CERN’s X-band test facility for CLIC. The dependence on power, and therefore on accelerating gradient, of the dark current signals is presented. The Fowler-Nordheim equation for field emission seems to be in accordance with the experimental data. Moreover, the analysis shows that the current intensity decreases as a function of time due to conditioning, but discrete jumps in the dark current signals are present, probably caused by breakdown events that change the emitters’ location and intensity., Proceedings of the 10th Int. Particle Accelerator Conf., IPAC2019, Melbourne, Australia

Low proton beam intensities (0.1-40 nA) are used for medical treatment of tumours at the PROSCAN facility in Paul Scherrer Institut (PSI). A cavity resonator using four quadrants operating in a dipole mode resonance has been developed to measure beam positions at these low intensities. The TM110 resonance frequency of 145.7 MHz is matched to the second harmonic of the beam pulse repetition rate (i.e.72.85 MHz). HFSS (High Frequency Structural Simulator) provides the BPM geometry and important parameters such as pickup position; dielectric dimensions etc. Comparison of test bench measurement and simulation provides good agreement. The measured position and signal sensitivity are limited by the noise, so that a position signal can be derived at beam intensities of at least 10 nA . We will discuss potential methods to increase the sensitivity. The dipole cavity resonator can be a promising candidate as a non-invasive position di-agnostic at the low proton beam intensities used in pro-ton therapy, Proceedings of the 10th Int. Particle Accelerator Conf., IPAC2019, Melbourne, Australia

The 2.0 GeV, 5 MW proton linac for the European Spallation Source, ESS, will have the capacity to accelerate additional pulses and send them to a neutrino target, providing an excellent opportunity to produce an unprecedented high performance neutrino beam, the ESS neutrino Super Beam, ESSnuSB, to measure, with precision, the CP violating phase at the 2nd oscillation maximum. In order to comply with the acceptance of the target and horn systems that will form the neutrino super beam, the long pulses from the linac must be compressed by about three orders of magnitude with minimal particle loss, something that will be achieved through multi-turn charge-exchange injection in an accumulator ring. This ring will accommodate over 2·10¹⁴ protons, which means that several design challenges are encountered. Strong space charge forces, low-loss injection with phase space painting, efficient collimation, a reliable charge stripping system, and e-p instabilities are some of the important aspects central to the design work. This paper presents the status of the accumulator ring design, with multi-particle simulations of the injections procedure.

The FCC-hh (Future Hadron-Hadron Circular Collider) is one of the options considered for the next generation accelerator in high-energy physics as recommended by the European Strategy Group. The latest changes brought to the lattice of the FCC-hh collider are commented: impact of the new intra-beam distance, efforts to increase the beam stay clear in the dispersion suppressors, tuning procedures, and updates on the insertions.

The discovery of oscillations and the latest progress in neutrino physics will make possible to observe for the first time a possible CP violation at the level of leptons. This will help to understand the disappearance of antimatter in the Universe. The ESSnuSB* project proposes to use the proton linac of the ESS currently under construction to produce a very intense neutrino Super Beam, in parallel with the spallation neutron production. The ESS linac is expected to deliver 5 MW average power, 2 GeV proton beam, with a rate of 14 Hz and pulse duration of 2.86 ms. By doubling the pulse rate, 5 MW power more can be provided for the production of the neutrino beam. In order to shorten the proton pulse duration to few μs requested by the neutrino facility, an accumulation ring is needed, imposing the use and acceleration of H⁻ instead of protons in the linac. The neutrino facility also needs a separate target station with a different design than the one of the neutron facility. On top of the target, a hadron magnetic collecting device is needed in order to focus the emerging hadrons from the target and obtain an intense neutrino beam directed towards the neutrino detector.

High gradient rf photo-injectors have been a key development to enable several applications of high quality electron beams. They allow the generation of beams with very high peak current and low transverse emittance, satisfying the tight demands for free-electron lasers, energy recovery linacs, Compton/Thomson sources and high-energy linear colliders. In the paper we present the design of a new full C-band RF photo-injector recently developed in the framework of the XLS-Compact Light design study and of the EuPRAXIA@SPARC_LAB proposal. It allows to reach extremely good beam performances in terms of beam emittance (at the level of few hundreds nm), energy spread and peak current. The photo-injector is based on a very high gradient (>200 MV/m) ultra-fast (RF pulses 200 ns) C-band RF gun, followed by two C band TW structures. Different types of couplers for the 1.6 cell RF gun have been considered and also a new compact low pulsed heating coupler working on the TM020 mode on the full cell has been proposed. In the paper we report the design criteria of the gun, the powering system, and the results of the beam dynamics simulations. We also discuss the case of 1 kHz repetition rate., Proceedings of the 10th Int. Particle Accelerator Conf., IPAC2019, Melbourne, Australia

For more than 20 years Cryogenic Current Comparators (CCC) are used to measure the current of charged particle beams with low intensity (nA-range). The device was first established at GSI in Darmstadt and was improved over the past two decades by the cooperation of institutes in Jena, GSI and CERN. The improved versions differ in material parameters and electronics to increase the resolution and in dimensions in order to meet the requirements of the respective application. The device allows non-destructive measurements of the charged particle beam current. The azimuthal magnetic field which is generated by the beam current is detected by low temperature Superconducting Quantum Interference Device (SQUID) current sensors. A complex shaped superconductor cooled down to 4.2 K is used as magnetic shielding and a high permeability core serves as flux concentrator. Three versions of the CCC shall be presented in this work: (1) GSI-Pb-CCC which was running at GSI Darmstadt in a transfer line, (2) CERN-Nb-CCC currently installed in the Antiproton Decelerator at CERN and (3) GSI-Nb-CCC-XD which will be operating in the CRYRING at GSI 2019. Noise, signal and drift measurements were performed in the Cryo-Detector Lab at the University of Jena., Proceedings of the 10th Int. Particle Accelerator Conf., IPAC2019, Melbourne, Australia

EuroCirCol is a conceptual design study of a Future Circular Collider (FCC-hh) which aims to expand the current energy and luminosity frontiers that the LHC has established. The vacuum chamber of this 50 TeV, 100 km collider, will have to cope with unprecedented levels of synchrotron radiation power for proton colliders, dealing simultaneously with a tighter magnet aperture. Since the high radiation power and photon flux will release large amounts of gas into the system, the difficulty to keep a low level of residual gas density increases considerably compared with the LHC. This article presents a study of the beam induced vacuum effects for the FCC-hh novel conditions, the different phenomena which, owing to the presence of the beam, have an impact on the vacuum level of the accelerator. To achieve this, a novel beam screen has been proposed, featuring specific mitigating measures aimed at dealing with the beam induced effects. It is concluded that thanks to the new beam screen design, the vacuum level in the FCC-hh shall be adequate, allowing to reach the molecular density requirement of better than 10¹⁵ H₂/m3 with baseline beam parameters within the first months of conditioning., Proceedings of the 10th Int. Particle Accelerator Conf., IPAC2019, Melbourne, Australia

After CERN’s Long Shutdown 2 (LS2) the Extra Low Energy Antiproton (ELENA) ring will begin providing extremely low energy (100 keV) antiproton beams to the antimatter experiments in the AD hall. To allow for simultaneous operation and guarantee maximum efficiency, all transfer lines will be based on electrostatic optics and short pulse (∼100 ns) deflectors. Currently, only a limited number of simulation codes allow a realistic representation of these elements, limiting the capabilities for beam quality optimization. In this contribution methods for modelling realistic electrostatic optical elements and perform 3D tracking studies through these are presented. A combination of finite element methods and experimental measurements are used along with a modified version of the G4Beamline and BMAD codes. Multi-objective optimization techniques are then applied to optimize beam transfer and beam quality at various points along the transfer lines., Proceedings of the 10th Int. Particle Accelerator Conf., IPAC2019, Melbourne, Australia

The ESSνSB project, recently granted by the EU H₂020 programme for a 4-year design study, proposes to use the protons produced by the linac (2 GeV, 5 MW) of the European Spallation Source (ESS) currently in construction in Lund (Sweden) to deliver a neutrino super beam. It follows the studies made by the FP7 Design Study EUROν[1] (2008-2012), regarding future neutrino facilities. The primary proton beam line completing the linear accelerator will consist of one or several accumulator rings and a proton beam switchyard. The secondary beam line producing neutrinos will consist of a four-horn/target station, a decay tunnel and a beam dump. A challenging component of this project is the enormous target heat-load generated by the 5 MW proton beam. In order to reduce this heat-load there will be four targets, which will be hit in sequence by the compressed proton pulses, thereby reducing the beam power on each target to 1.25 MW. Following the EUROν studies, a packed bed of titanium spheres cooled with helium gas has become the baseline design for a Super Beam based on a 2-5 GeV proton beam with a power of up to 1 MW per target, with other targets being considered for comparison. The hadron collection will be performed by four hadron collectors (magnetic horns), one for each target. Each of these target/hadron-collector assemblies will receive proton pulses three times more frequently than in present projects, and by an average beam power of 1.25 MW, which is twice as high as in present neutrino projects. The feasibility of the target/horn station for the ESSνSB project is discussed here.

Proton computed tomography aims to increase the accuracy of proton treatment planning by directly measuring proton stopping power. This imaging technique requires a proton beam of 330 MeV incident kinetic energy for adult patients. Employing superconducting technology in the beam delivery system allows it to be of comparable size to a conventional proton therapy gantry. A superconducting bending magnet design for a proton computed tomography gantry is proposed in this paper. The 30 deg, 3.9 T canted-cosine-theta dipole wound with NbTi wires is used to steer 330 MeV protons in an isocentric beam delivery system which rotates around the patient. Two methods of magnetic field shielding are compared in the context of proton therapy facility requirements; traditional passive shielding with an iron yoke placed around the magnet and an active shielding option utilising extra layers of the superconducting coil., Proceedings of the 10th Int. Particle Accelerator Conf., IPAC2019, Melbourne, Australia

The Future Circular Collider (FCC-hh) is being designed as a 100 km ring that should collide 50 TeV proton beams. At 8.3 GJ, its stored beam energy will be a factor 28 higher than what has been achieved in the Large Hadron Collider, which has the highest stored beam energy among the colliders built so far. This puts unprecedented demands on the control of beam losses and collimation, since even a tiny beam loss risks quenching superconducting magnets. We present in this article the design of the FCC-hh collimation system and study the beam cleaning through simulations of tracking, energy deposition, and thermo-mechanical response. We investigate the collimation performance for design beam loss scenarios and potential bottlenecks are highlighted.

There is a matter-antimatter asymmetry observed in the universe that can not be explained by the Standard Model of particle physics. To resolve that problem additional CP violating phenomena are needed. A candidate for an additional CP violating phenomenon is a non-vanishing Electric Dipole Moment (EDM) of subatomic particles. Since permanent EDMs violate parity and time reversal symmetries, they also violate CP if the CPT-theorem holds. The Jülich Electric Dipole moment Investigation (JEDI) Collaboration works on a direct measurement of the electric dipole moment (EDM) of protons and deuterons using a storage ring. The JEDI experiment requires a small beam orbit RMS in order to measure the EDM. Therefore an ongoing upgrade of the Cooler Syncrotron (COSY) is done in order to improve the precision of the beam position. One of part of this upgrade is to determine the magnetic center of the quadrupoles with respect to the beam position monitors. This can be done with the so called beam-based alignment method. The first results of the beam-based alignment measurement performed in February 2019 will be presented., Proceedings of the 10th Int. Particle Accelerator Conf., IPAC2019, Melbourne, Australia

The FCC-hh (Future Hadron-Hadron Circular Collider) is one of the options considered for the next generation accelerator in high-energy physics as recommended by the European Strategy Group. The evaluation of the various magnets mechanical error and field error tolerances in the arc sections of FCC-hh, as well as an estimation of the required correctors strengths, are important aspects of the collider design. In this study the mechanical tolerances, dipole and quadrupole field error tolerances for the arc sections of FCC-hh are evaluated. The consolidated correction schemes of the linear coupling (with skew quadrupoles) and of the beam tunes (with normal quadrupoles) are presented. The integration of the different ring insertions (interaction region, collimation, injection, etc) is also discussed.

The CompactLight project is currently developing the design of a next generation hard X-ray FEL facility, based on high-gradient X-band (12 GHz) structures, bright electron photo-injectors, and compact short period undulators. However, to improve the brightness limitations due to the non-linear energy spread of the electron bunches, a K-band (36 GHz) linearizer is being considered to provide a harmonic compensation during the bunch compression. In this paper, we analyze the feasibility of such linearizer., Proceedings of the 10th Int. Particle Accelerator Conf., IPAC2019, Melbourne, Australia

The European Spallation Source (ESS), currently under construction in Lund, Sweden, is the world’s most powerful neutron spallation source, with an average power of 5 MW at 2.0 GeV. In the ESS neutrino Super Beam Project (ESSnuSB) it is proposed to utilise this powerful accelerator as a proton driver for a neutrino beam that will be sent to a large underground Cherenkov detector in Garpenberg, mid-Sweden. In this paper we discuss the required modifications of the ESS linac to reach an additional 5 MW beam power for neutrino production in parallel to the spallation neutron production., Proceedings of the 10th Int. Particle Accelerator Conf., IPAC2019, Melbourne, Australia