Proton Synchrotron Accelerator Research Articles

Laboratory realization of relativistic pair-plasma beams

Relativistic electron-positron plasmas are ubiquitous in extreme astrophysical environments such as black-hole and neutron-star magnetospheres, where accretion-powered jets and pulsar winds are expected to be enriched with electron-positron pairs. Their role in the dynamics of such environments is in many cases believed to be fundamental, but their behavior differs significantly from typical electron-ion plasmas due to the matter-antimatter symmetry of the charged components. So far, our experimental inability to produce large yields of positrons in quasi-neutral beams has restricted the understanding of electron-positron pair plasmas to simple numerical and analytical studies, which are rather limited. We present the first experimental results confirming the generation of high-density, quasi-neutral, relativistic electron-positron pair beams using the 440 GeV/c beam at CERN’s Super Proton Synchrotron (SPS) accelerator. Monte Carlo simulations agree well with the experimental data and show that the characteristic scales necessary for collective plasma behavior, such as the Debye length and the collisionless skin depth, are exceeded by the measured size of the produced pair beams. Our work opens up the possibility of directly probing the microphysics of pair plasmas beyond quasi-linear evolution into regimes that are challenging to simulate or measure via astronomical observations.

New physics searches using ProtoDUNE and the CERN SPS accelerator

The exquisite capabilities of liquid Argon Time Projection Chambers make them ideal to search for weakly interacting particles in Beyond the Standard Model scenarios. Given their location at CERN the ProtoDUNE detectors may be exposed to a flux of such particles, produced in the collisions of 400 GeV protons (extracted from the Super Proton Synchrotron accelerator) on a target. Here we point out the interesting possibilities that such a setup offers to search for both long-lived unstable particles (Heavy Neutral Leptons, axion-like particles, etc) and stable particles (e.g. light dark matter, or millicharged particles). Our results show that, under conservative assumptions regarding the expected luminosity, this setup has the potential to improve over present bounds for some of the scenarios considered. This could be done within a short timescale, using facilities that are already in place at CERN, and without interfering with the experimental program in the North Area at CERN.

The Use of the BIM Approach from the Conceptual Planning to the Construction Phase: The Case Study of the SHiP Experiment

The Search for Hidden Particles (SHiP) experiment is a new purpose fixed target facility proposed for the CERN Super Proton Synchrotron accelerator to search for long-lived exotic particles associated with Hidden Sectors and Dark Matter. This paper reports on the development of BIM integrated design for the SHiP experiment, applied initially to the Decay Volume, a >2000 m3 conical steel vessel under a vacuum hosting several large particle physics detector systems. A BIM methodology is used to address all the design phases of the Decay Volume of the SHiP experiment from the conceptual planning to the constructive drawings production. This proposed workflow is a basic plan to be repeated for each sub-component of the SHiP experiment in order to have a full and overall integration of the experiment. In particular, the Decay Volume’s geometrical and structural design and the simulation of its assembly process, both in factory and on site, are proposed. Moreover, the use of collaborative platforms to speed up the ideas exchange, as the basis of a highly multidisciplinary and complex project, is discussed. The complexity, multidisciplinary nature, and size of the SHiP project severely challenge design information management. The final plan to solve this issue is to have a BIM integrated design of each experiment sub-component, such as that demonstrated in this work for the Decay Volume, in order to have a full and multidisciplinary integration of the overall project.

Prospects in the search for a new light Z′ boson with the NA64μ experiment at the CERN SPS

A light ${Z}^{\ensuremath{'}}$ vector boson coupled to the second and third lepton generations through the ${L}_{\ensuremath{\mu}}\ensuremath{-}{L}_{\ensuremath{\tau}}$ current with mass below 200 MeV provides a very viable explanation in terms of new physics to the recently confirmed $(g\ensuremath{-}2{)}_{\ensuremath{\mu}}$ anomaly. This boson can be produced in the bremsstrahlung reaction $\ensuremath{\mu}N\ensuremath{\rightarrow}\ensuremath{\mu}N{Z}^{\ensuremath{'}}$ after a high energy muon beam collides with a target. $\mathrm{NA}64\ensuremath{\mu}$ is a fixed-target experiment using a 160 GeV muon beam from the CERN Super Proton Synchrotron accelerator looking for ${Z}^{\ensuremath{'}}$ production and its subsequent decays, ${Z}^{\ensuremath{'}}\ensuremath{\rightarrow}\mathrm{invisible}$. In this paper, we present the study of the $\mathrm{NA}64\ensuremath{\mu}$ sensitivity to search for such a boson. This includes a realistic beam simulation, a detailed description of the detectors and a discussion about the main potential background sources. A pilot run is scheduled in order to validate the simulation results. If those are confirmed, $\mathrm{NA}64\ensuremath{\mu}$ will be able to explore all the remaining parameter space which could provide an explanation for the $g\ensuremath{-}2$ muon anomaly in the ${L}_{\ensuremath{\mu}}\ensuremath{-}{L}_{\ensuremath{\tau}}$ model.

Probing hidden sectors with a muon beam: Total and differential cross sections for vector boson production in muon bremsstrahlung

Vector bosons, such as Dark Photon $A'$ or $Z'$, can couple to muons and be produced in the bremsstrahlung reaction $\mu^- + N \rightarrow \mu^- + N + A'(Z')$. Their possible subsequent invisible decay can be detected in fixed target experiments through missing energy/momentum signature. In such experiments, not only is the energy transfer to $A'(Z')$ important, but also the recoil muon angle $\psi_{\mu'}$. In this paper, we derive the total and the double differential cross-sections involved in this process using the phase space Weisz\"acker-Williams and improved Weisz\"acker-Williams approximations, as well as using exact-tree-level calculations. As an example, we compare the derived cross-sections and resulting signal yields in the NA64$\mu$ experiment that uses a 160 GeV muon beam at the CERN Super Proton Synchrotron accelerator. We also discuss its impact on the NA64$\mu$ expected sensitivity to explore the $(g-2)_\mu$ anomaly favoured region with a $Z'$ boson considering $10^{12}$ muons accumulated on target.

Search for light dark matter in the NA64 experiment

We review the most important models of light dark matter and discuss the NA64 experiment aimed at searching for hypothetical particles, including dark matter, in the mass range ⩽ O (1) GeV with the use of electron and muon beams at the Super Proton Synchrotron (SPS) accelerator at CERN. We consider the methods and results of searches in the NA64 and other accelerator experiments and also discuss their further prospects.

Omnidirectional Robotic Platform for Surveillance of Particle Accelerator Environments with Limited Space Areas

Intelligent robotic systems are becoming essential for inspections and measurements in harsh environments. This article presents the design of an omnidirectional robotic platform for tunnel inspection with spatial limitations. This robot was born from the need to automate the surveillance process of the Super Proton Synchrotron (SPS) accelerator of the European Organization for Nuclear Research (CERN), where there is remaining radiation. The accelerator is located within a tunnel that is divided by small doors of 400 × 200 mm dimensions, through which the robot has to cross. The designed robot brings a robotic arm, and the needed devices to carry out the inspection. Thanks to this design, the robot application may vary by replacing certain devices and tools. In addition, this paper presents the kinematic and dynamic control models for the robotic platform.

Study of energy response and resolution of the ATLAS Tile Calorimeter to hadrons of energies from 16 to 30 GeV

Three spare modules of the ATLAS Tile Calorimeter were exposed to test beams from the Super Proton Synchrotron accelerator at CERN in 2017. The detector’s measurements of the energy response and resolution to positive pions and kaons, and protons with energies ranging from 16 to 30 GeV are reported. The results have uncertainties of a few percent. They were compared to the predictions of the Geant4-based simulation program used in ATLAS to estimate the response of the detector to proton-proton events at the Large Hadron Collider. The determinations obtained using experimental and simulated data agree within the uncertainties.

The BIM-based Integrated Design of the SHiP Project Decay Volume

The Search for Hidden Particles (SHiP) experiment is a new general-purpose fixed target facility proposed at the CERN Super Proton Synchrotron accelerator to search for long- lived exotic particles associated with Hidden Sectors and Dark Matter. This paper reports on the BIM integrated design of SHiP’s decay volume, a conical steel vessel under vacuum that should host several large particle physics detector systems. The use of BIM characterized the design of the decay volume, both in the modeling and structural design phase, and in the process definition phase for the realization and implementation in the facility of the device. This procedure helps to minimize the risks of incorrect design and construction of the device during the whole process. With the automation of the virtual model and the use of interoperable software, in addition to speeding up the exchange of information, it is possible also to export the detailed information of the structural design directly to the numerical control machines for the prefabrication of the various steel modules. Then, the BIM approach to support the integrated design of the SHiP project decay volume from the conceptual planning to the construction phase is shown in this work.

The structural design of the decay volume for the Search for Hidden Particles (SHIP) project

The Search for Hidden Particles (SHiP) experiment is a new general-purpose fixed target facility proposed at the CERN Super Proton Synchrotron (SPS) accelerator to search for long-lived exotic particles associated with Hidden Sectors and Dark Matter. This paper reports on the structural design of SHiP’s decay volume, a > 2000 m3 conical vessel under vacuum that should host several large particle physics detector systems. In the field of structural and seismic engineering, the design study in a very multidisciplinary international collaboration has represented a stimulating research challenge. The goal of the design of the decay is to produce a structure as light and as slim as possible to stay within the geometrical envelop determined in the physics simulations. A complete study has been performed with all the steps from the conceptual design, including the interaction with other components and the plant systems, to the assembly procedures for the decay volume realization. The complexity of the case study has been driven by the need of finding the appropriate compromise between the physics performance, the structural aspects, the executive, constructive and operational issues, and the economical constraints. The assembly strategy, the welding techniques, and the expected construction time are discussed in view of the extremely complex installation phase. Building Integrated Model (BIM) methodology is also proposed as an essential tool to coordinate the entire process of designing and managing not only the decay volume but the entire project.

Upgrade of the ATLAS Hadronic Tile Calorimeter for the High Luminosity LHC

The ATLAS hadronic Tile Calorimeter (TileCal) will undergo major upgrades to the on- and off-detector electronics in preparation for the high luminosity programme of the LHC (HL-LHC) in 2026. The system will cope with the HL-LHC increased radiation levels and out-of-time pileup. The on-detector electronics of the upgraded system will continuously digitize and transmit all photomultiplier signals to the off-detector systems at a 40 MHz rate. The off-detector electronics will store the data in pipeline buffers, reconstruct cell energy, produce digital hadronic cell sums of various granularity and send it to the Level-0 calorimeter trigger system, finally read out selected events. The modular front-end electronics feature radiation-tolerant commercial off-the-shelf components and redundant design to minimise single points of failure. The timing, control and communication interface with the off-detector electronics is implemented with modern Field Programmable Gate Arrays (FPGAs) and high speed fibre optic links running up to 9.6 Gb/s. The TileCal upgrade program has included extensive R&D and test beam studies using the beams from the Super Proton Synchrotron (SPS) accelerator at CERN. A Demonstrator module equipped with the novel electronics for the HL-LHC upgrade and compatible with the existing ATLAS read-out chain inserted in ATLAS in August 2019 for testing in actual detector conditions. We present the status of the upgrade program, the results using muon, electron and hadron beams at various incident energies and impact angles collected in 2015-2018, combined results of Demonstrator tests and calibration runs to evaluate the readiness of the new design.

Beam tests on the ATLAS tile calorimeter demonstrator module

The Large Hadron Collider (LHC) Phase-II upgrade aims to increase the accelerator luminosity by a factor of 5–10. Due to the expected higher radiation levels and the aging of the current electronics, a new read-out system of the ATLAS experiment hadronic calorimeter (TileCal) is needed. A Demonstrator prototype of the electronics has been tested during different testbeam campaigns at the Super Proton Synchrotron (SPS) accelerator of CERN with the purpose of checking the calibration and determining the performance of the detector by exploiting the features of the interactions of different particles with matter. We present the current status and results where the Demonstrator new electronics were situated in calorimeter modules and data were collected by exposing it to beams of muons, electrons and hadrons, at various incident energies and impact angles.

Design Development for the Beam Dump Facility Target Complex at CERN

CERN has launched a study phase to evaluate the feasibility of a new high-intensity beam dump facility at the CERN Super Proton Synchrotron accelerator with the primary goal of exploring Hidden Sector models and searching for Light Dark Matter, but which also offers opportunities for other fixed target flavour physics programs such as rare tau lepton decays and tau neutrino studies. The new facility will require—among other infrastructure—a target complex in which a dense target/dump will be installed, capable of absorbing the entire energy of the beam extracted from the SPS accelerator. In theory, the target/dump could produce very weakly interacting particles, to be investigated by a suite of particle detectors to be located downstream of the target complex. As part of the study, a development design of the target complex has been produced, taking into account the handling and remote handling operations needed through the lifetime of the facility. Two different handling concepts have been studied and both resulting designs are presented.

Study of high baryon density QCD matter at J-PARC-HI

Abstract J-PARC is a Japanese proton synchrotron accelerator facility, and is under consideration of an upgrade for accelerating heavy ions. A beam rate of about 10 11 Hz is expected with the upgraded accelerator scheme, with which the QCD phase structure, hadrons under a high baryon density, and multi-strange hypernuclei can be studied. In this paper, we discuss the plan for the upgrade and the conceptual design of the detectors for several physics cases.

Performance of a tungsten–cerium fluoride sampling calorimeter in high-energy electron beam tests

A prototype for a sampling calorimeter made out of cerium fluoride crystals interleaved with tungsten plates, and read out by wavelength-shifting fibres, has been exposed to beams of electrons with energies between 20 and 150 GeV, produced by the CERN Super Proton Synchrotron accelerator complex. The performance of the prototype is presented and compared to that of a Geant4 simulation of the apparatus. Particular emphasis is given to the response uniformity across the channel front face, and to the prototype's energy resolution.

Development and test of a rectangular CERN ConFlat-type flange

Abstract Standard circular ConFlat ® (CF) flanges are widely used in industry due to their high sealing reliability after being subjected to a bakeout process. The Beam Gas Ionisation (BGI) instrument for the CERN Proton Synchrotron accelerator will require a CF-like rectangular sealing system. Although rectangular CF-type flanges with plastically deforming metal seals have been used, no published designs with validated tests for bakeout under UHV conditions are available. Existing circular CERN CF flanges were compared and a design for a rectangular CF flange was proposed. Two prototypes were manufactured along with copper gaskets. The flanges and gaskets were cleaned and prepared for extensive vacuum testing after bakeout cycles up to 350 °C. This paper summarises the design, analysis and manufacturing process and describes the testing procedures and results. Additionally, the limitations when designing a flange of any shape were explored.

Metrological Performance of a Ferrimagnetic Resonance Marker for the Field Control of the CERN Proton Synchrotron

In particle accelerators, “field markers” provide a digital trigger when the magnetic field crosses a given threshold. In this paper, the metrological characterization of a magnetic field marker, based on a ferrimagnetic resonance transducer referencing the flux sensed by a coil, is reported. The experimental results of a validation test campaign at the European Organization for Nuclear Research (CERN) to test the marker in static as well as fast ramping fields (up to 2.5 T/s) are illustrated. The repeatability of attained in the range (60 to 100) mT is very promising to increase the performance of the Proton Synchrotron accelerator at CERN.

Hadron fluence measurements with LiF-TLD sensors at the proton synchrotron accelerator at CERN

In view of the implementation of beam-monitoring sensors for CERN's Large Hadron Collider (LHC), and also in order to validate Thermoluminescence Detectors as a versatile tool to measure ionizing radiation doses in mixed fields at hadron colliders such as the LHC, chemical vapor deposition diamond sensors have been evaluated and calibrated at CERN's Proton Synchrotron accelerator. Special attention was paid to understanding whether lithiumfluoride thermoluminescence detectors are suitable as measuring devices in these radiation fields.

The response of TL lithium fluoride detectors to 24 GeV/c protons for doses ranging up to 1 MGy

A new method of thermoluminescent (TL) measurement of radiation doses ranging from micrograys up to a megagray has been recently developed at IFJ. This method is based on a newly discovered behavior of LiF:Mg,Cu,P detectors at doses exceeding 1 kGy. Significant changes in their glow-curves are observed at higher doses; of special importance is occurrence of a new, well separated peak for doses above 50 kGy, thus these detectors can be used for measurements of doses at ultra-high dose range. In order to check the glow-curve features in the high dose region for different types of LiF:Mg,Cu,P and LiF:Mg,Ti detectors after irradiation with heavy charged particles, tests at the 24 GeV/c proton beam of IRRAD1 irradiation zone at the CERN Proton Synchrotron accelerator up to 1 MGy were performed. The occurrence of the high dose peak in the glow-curve of LiF:Mg,Cu,P detectors resulting from heavy particles irradiation was confirmed. Results of this investigation are presented in this paper.

Radiation Shielding Calculations for the 3-GeV Proton Synchrotron Accelerator in the J-PARC Facility

Radiation shielding calculations for the subject of bulk shielding, duct streaming and skyshine were performed for the shielding design of the 3-GeV proton synchrotron accelerator in the J-PARC facility with both the simplified calculation methods including semi-empirical formulas and the Monte Carlo methods. Calculation results of dose rates at the boundary of radiation controlled area and the site boundary are compared with the dose limit defined in the regulation law of Japan.