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An Inductive Pick-Up (IPU) senses the azimuthal distribution of the beam image current. Its construction is similar to a wall current monitor, but the pick-up inner wall is divided into electrodes, each of which forms the primary winding of a toroidal transformer. The beam image current component flowing along each electrode is transformed to a sec...
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An Inductive Pick-Up (IPU) senses the azimuthal distribution of the beam image current. Its construction is similar to a wall current monitor, but the pick-up inner wall is divided into electrodes, each of which forms the primary winding of a toroidal transformer. The beam image current component flowing along each electrode is transformed into a s...
Citations
... Devices using a similar beam-coupling method were realised in the past [12][13][14] but they were all designed for measuring the transverse beam position at relatively low frequencies. The WCT developed by the authors is optimised for the precise measurement of the intensity of the LHC short bunches. ...
The Large Hadron Collider (LHC) stores two high-energy counter-rotating particle beams consisting of multiple bunches of a nanosecond length. Precise knowledge of the number of particles within each bunch, known as the bunch intensity, is crucial for physicists and accelerator operators. From the very beginning of the LHC operation, bunch intensity was measured by four commercial fast beam current transformers (FBCTs) coupling to the beam current. However, the FBCTs exhibited several shortcomings which degraded the measurement accuracy below the required level. A new sensor, the wall current transformer (WCT), has been developed to overcome the FBCT limitations. The WCT consists of eight small radio frequency (RF) current transformers distributed radially around the accelerator’s vacuum chamber. Each transformer couples to a fraction of the image current induced on the vacuum chamber by the passing particle beam. A network of RF combiners sums the outputs of all transformers to produce a single signal which, after integration, is proportional to the bunch intensity. In laboratory tests and during beam measurements, the WCT performance was demonstrated to convincingly exceed that of the FBCT. All originally installed FBCTs were replaced by four WCTs, which have been serving as the LHC reference bunch intensity sensors since 2016.
... These are solutions that aim to measure the beam properties with minimal disturbance, ensuring that monitoring can take place without disrupting the beam. Examples of non-destructive detectors include inductive pick-ups, which use coils located around the beam pipe to measure magnetic field variations and determine the beam's position and intensity [10], and Secondary-Emission Monitors (SEM's) [11]. SEM's rely on the emission of low-energy electrons that is produced when charged particles strike a metal surface. ...
A two-dimensional beam monitoring detector named π2 has been developed and tested at the Bern University Hospital, using an 18 MeV proton beam provided by a medical cyclotron. This non-destructive device utilises a scintillating compound (P47 phosphor) coated onto a thin aluminium foil that is angled at 45∘ with respect to the beam axis. The scintillating light produced when the beam passes through the foil is captured by a CMOS camera, resulting in a two-dimensional image of the beam profile. Custom software is then used to analyse the image and extract valuable information about the beam’s position, shape, and intensity. The focus of the experimental work was on characterising the performance of the π2 with the 18 MeV proton beam. The linearity of the detector’s output signal was evaluated for proton fluxes ranging from 2·1010cm−2·s−1 to 5·1011cm−2·s−1. Furthermore, the beam profiles measured with the π2 were found to be consistent with reference measurements obtained using alternative beam monitors. Additionally, the experiments also involved studying the beam scattering caused by the foil and scintillating layer. Finally, in a long-term radiation test, the detector demonstrated a stable response up to an integrated proton flux of 3·1015cm−2. The π2 is currently being used at the Bern cyclotron for monitoring beams in the development of new methods for medical radioisotope production and for radiation hardness studies. The π2 has potential applications in several fields that involve the use of accelerated ions, such as cancer particle therapy, medical radioisotope production and radiation hardness studies.
... Charge calibration was performed against the Bergoz ICTs installed, and position calibration was performed using adjacent BTV screens. The BPMs were originally designed for use in the CTF3 drive beam [28], and their electronics were modified to work at the relatively low charges available on CLEAR. Currently they are not sensitive to short bunch trains, so further optimisation will be explored. ...
The CERN Linear Electron Accelerator for Research (CLEAR) at CERN has been operating since 2017 as a dedicated user facility providing beams for a varied range of experiments. CLEAR consists of a 20 m long linear accelerator (linac), able to produce beams from a Cs 2 Te photocath-ode and accelerate them to energies of between 60 MeV and 220 MeV. Following the linac, an experimental beamline is located, in which irradiation tests, wake-field and impedance studies, plasma-lens experiments, beam-diagnostics development , and terahertz (THz) emission studies, are performed. In this paper, we present recent upgrades to the entire beam-line, as well as the design of future upgrades, such as a dogleg section connecting to an additional proposed experimental beamline. The gain in performance due to these upgrades is presented with a full range of available beam properties documented.
... Inductive pickups, which are used for broadband bunch observations, to measure beam image current are limited by parasitic inductances at low frequencies for instance at the Drive Beam Linac of the Third CLIC Test Facility (CTF3 DBL) at CERN [16]. Wall Current Monitors (WCM) [17], due to their broadband capability, will have a higher thermal noise level which will limit their sensitivity to measure low beam currents of 0.1-10nA in the PROSCAN beamlines. ...
At PSI (Paul Scherrer Institute), Switzerland, a superconducting cyclotron called "COMET" delivers proton beam of 250 MeV pulsed at 72.85 MHz for proton radiation therapy. Measuring proton beam currents (0.1-10nA) is of crucial importance for the treatment safety and is usually performed with invasive monitors such as ionisation chambers (ICs) which degrade the beam quality. A new non-invasive beam current monitor working on the principle of electromagnetic resonance is built to replace ICs in order to preserve the beam quality delivered. The fundamental resonance frequency of the resonator is tuned to 145.7 MHz, which is the second harmonic of the pulse rate, so it provides signals proportional to beam current. The cavity resonator installed in the beamline of the COMET is designed to measure beam currents for the energy range 238-70 MeV. Good agreement is reached between expected and measured resonator response over the energy range of interest. The resonator can deliver beam current information down to 0.15 nA for a measurement integration time of 1 s. The cavity resonator might be applied serving as a safety monitor to trigger interlocks within the existing domain of proton radiation therapy. Low beam currents limit the abilities to detect sufficiently, however, with the potential implementation of FLASH proton therapy, the application of cavity resonator as an online beam-monitoring device is feasible.
... The source and injector will be reusing the existing CLEAR facility along with its current beam instrumentation. The latter will benefit from the most recent development in beam instrumentation performed on CLEAR for low beam charge using inductive BPMs [29]. The beam position monitors along the X-band linac will be based on RF cavities also developed for the CLIC main linac [30]. ...
... Fourteen new inductive beam position monitors [29] are required to measure the beam trajectory through the transfer line, with two new Optical Transition Radiation Beam TeleVision (OTR-BTV) systems [31] foreseen to measure the average beam size at the beginning and the end of the transfer line. ...
The design of a primary electron beam facility at CERN is described. It re-enables the SPS as an electron accelerator, and leverages the development invested in CLIC technology for its injector and as accelerator R&D infrastructure. The facility would be relevant for several of the key priorities in the 2020 update of the European Strategy for Particle Physics, such as an electron-positron(e-p) Higgs factory, accelerator R&D, dark sector physics, and neutrino physics. In addition, it could serve experiments in nuclear physics. The electron beam delivered by this facility would provide access to light dark matter production significantly beyond the targets predicted by a thermal dark matter origin, and for natures of dark matter particles that are not accessible by direct detection experiments. It would also enable electro-nuclear measurements crucial for precise modelling the energy dependence of neutrino-nucleus interactions, which is needed to precisely measure neutrino oscillations as a function of energy. The implementation of the facility is the natural next step in the development of X-band high-gradient acceleration technology, a key technology for compact and cost-effective electron/positron linacs. It would also become the only facility with multi-GeV drive bunches and truly independent electron witness bunches for plasma wakefield acceleration. The facility would be used for the development and studies of a large number of components and phenomena for a future e-p Higgs and electroweak factory as the first stage of a next circular collider at CERN, and its cavities in the SPS would be the same type as foreseen for such a future collider. The operation of the SPS with electrons would train a new generation of scientists. The facility could be made operational in about five years and would operate in parallel and without interference with Run 4 at the LHC.
... Ce courant de retour est l'image du courant du faisceau. • Les collecteurs capacitifs [42] ou inductifs [43] qui permettent de mesurer le courant (ou la position) d'un faisceau suite a son interaction avec des conducteurs cylindriques placées dans le tube de propagation. • Les transformateurs de courant [44] qui convertissent le champ propre du faisceau en un courant mesurable. ...
Une des applications des faisceaux intenses d’électrons relativistes est la caractérisation de matériaux soumis à leur irradiation. L’étude des chocs en résultant permet de développer et de valider les équations d’états de ces matériaux. Au CEA/CESTA nousdisposons de deux générateurs qui seront décrits et utilisés dans cette thèse. CESAR est un générateur produisant un faisceau d’électrons de 800 keV, 300 kA, sur une durée de 60 ns. En raison du fort courant, le faisceau est transporté dans 1 mbar d’air puis il est focalisé grâce à un champ magnétique externe. Le temps de fonctionnement de CESAR est divisé en deux parties : la caractérisation du faisceau émis et l’étude de matériaux soumis à des chocs par le dépôt d’énergie des électrons. Pour simuler le comportement du matériau cible pendant l’expérience, nous utilisons deux codes de calculs. Le premier, Diane, calcule le dépôt d’énergie des électrons dans la cible. Le second, Hésione, utilise les résultats de Diane pour simuler l’hydrodynamique de cette dernière qui est associée au dépôt d’énergie. Pour initialiser les calculs, nous utilisons les résultats des expériences de caractérisation du faisceau (énergie cinétique des électrons, courant et homogénéité du faisceau). Dans le cas de CESAR à haute fluence (700 cal/cm2), nous montrerons que l’énergie des électrons doit diminuer durant leur transport dans le gaz pour restituer correctement les expériences par les simulations. En parallèle, nous utilisons le générateur RKA pour étudier la physique de l’interaction d’un faisceau d’électrons (500 keV, de 3 à 30 kA, 100 ns) de basse fluences (quelques cal/cm2) avec un gaz, ceci en collaboration avec le laboratoire américain "Sandia National Laboratories". Le faisceau produit, très reproductible, est transporté dans de l’argon à une pression variable et il a été caractérisé finement dans ce travail de thèse. Les résultats des expériences seront comparés aux prévisions des codes de calculs CALDER (CEA-DAM) et EMPIRE (SNL) afin de valider ces derniers.
... Moreover, a few diagnostic taken from the now discontinued Drive Beam lines have been adapted and installed to fit the CLEAR beam specifications. This includes a high bandwidth Wall Current Monitor (WCM), two Drive Beam Inductive BPMs48 and a wave guide pickup (BPRW) for non-destructive bunch length measurements49 .The following CLIC Test area consists of the existing CLIC Two Beam Module (about 3 m long) on which a CLIC accelerating structure and three CLIC cavity BPM (BPC 660, BPC 670 and BPC 680) prototypes plus one older BPM (BPC 690) prototype are installed allowing the continuation of Wake Field Monitor (WFM)50 , and BPMs 51 studies. The transverse position of the three new prototype CLIC cavity BPMs and of the CLIC structure is remotely adjustable to allow for precise relative positioning. ...
In this thesis, the beam dynamics, namely the normalized emittance, energy and energy spread at LINAC exit of SIRIUS are studied. The interest is mainly assessed if the beam parameters meet the necessary requirement for its proper injection into the Booster. In the Single-Bunch mode, an energy of 147.8 ± 0.2 MeV was obtained with energy spread percentage of 0.18 ± 0.01 %, normalized emittance of 53.855 ± 0.007 mm.mrad for the horizontal plane and 51.07 ± 0.02 mm.mrad for the vertical plane. In the Multi-Bunch mode, energy of 147.6 ± 0.2 MeV with energy spread percentage 0.41 ± 0.02 %, normalized emittance 50.747 ± 0.005 mm.mrad in the horizontal plane and 61.567 ± 0.007 mm.mrad in the vertical plane were obtained. These data were input in a simulation to determine the quadrupole strength in the transport line magnets. Experimentally, this magnet configuration creates a stable electron beam transport towards the Booster. On the other hand, the new Basler digital system installed at CLEAR was tested and to measure its efficiency, beam emittance and Twiss parameters were assessed by comparing the results of the Basler digital system with the results of the traditional BTV system. The new digital system provides better results regarding the quality and resolution of the images obtained. It also shows a smaller standard error of the mean beam size, which led to a lower error in the emittance and Twiss parameters calculation. In addition, Monte Carlo was used to propagate the errors. In general, the Basler results closely resemble those of BTV system, especially in quadrupole current ranges near and equidistant to the minimum point of the parabola obtained after the quadrupole scan. In the horizontal plane, beam size values for current ranges far from the minimum point tend to create slightly different parabolas in both cameras leading to different results. In the vertical plane, this issue was not observed. The main culprit seems to be a bad alignment in the physical installation of the Basler system. In the horizontal plane, a normalized emittance of 16.96 ± 0.01 mm.mrad and 13.843 ± 0.004 mm.mrad and in the vertical plane were obtained for the BTV camera. On the other hand, a normalized emittance of 16.94 ± 0.01 mm.mrad in the horizontal plane and 13.94 ± 0.01 mm.mrad in the vertical plane for the Basler system were obtained. All these calculation were done with a beam energy of 200 MeV.
... These monitors make direct use of the image current flowing on the wall of the vacuum chamber. A ceramic gap is used to force the image current through external resistors, in the case of the resistive (wall current) monitor, or through metallic rods fitted with transformers in the case of the inductive pick-up [122]. The position is calculated by comparing the output from suitably placed resistors or rods. ...
Magnets are at the core of both circular and linear accelerators. The main function of a magnet is to guide the charged particle beam by virtue of the Lorentz force, given by the following expression:where q is the electrical charge of the particle, v its velocity, and B the magnetic field induction. The trajectory of a particle in the field depends hence on the particle velocity and on the space distribution of the field. The simplest case is that of a uniform magnetic field with a single component and velocity v normal to it, in which case the particle trajectory is a circle. A uniform field has thus a pure bending effect on a charged particle, and the magnet that generates it is generally referred to as a dipole.
... For the purpose of the experiment we measured current with the beam position monitors (BPM) installed right next to the delay loop as well as in the transfer lines (TL), combiner ring, TBL and TBM, see Figs. 10 and 11. Details on various monitor designs used in CTF3 can be found in [20][21][22]. ...
The Compact Linear Collider (CLIC) is a study for an electron–positron machine aiming at accelerating and colliding particles at the next energy frontier. The CLIC concept is based on the novel two-beam acceleration scheme, where a high-current low-energy drive beam generates RF in series of power extraction and transfer structures accelerating the low-current main beam. To compensate for the transient beam-loading and meet the energy spread specification requirements for the main linac, the RF pulse shape must be carefully optimized. This was recently modelled by varying the drive beam phase switch times in the sub-harmonic buncher so that, when combined, the drive beam modulation translates into the required voltage modulation of the accelerating pulse. In this paper, the control over the RF pulse shape with the phase switches, that is crucial for the success of the developed compensation model, is studied. The results on the experimental verification of this control method are presented and a good agreement with the numerical predictions is demonstrated. Implications for the CLIC beam-loading compensation model are also discussed.
... Presently, it host a chamber for Optical (Diffraction) Transition Radiation Interferometry (OTRI/OTDRI) studies [26]. Moreover, a few diagnostic taken from the now discontinued Drive Beam lines have been adapted and installed to fit the CLEAR beam specifications [27][28][29]; This includes a High Bandwidth Wall Current Monitor (WCM) [30], two Drive Beam Inductive BPMs [31] and a wave guide pickup (BPRW) for non-destructive bunch length measurements [32]. ...
The conversion of the CALIFES beamline of CTF3 into the "CERN Linear Electron Accelerator for Research" (CLEAR) facility was approved in December 2016. The primary focus for CLEAR is general accelerator R&D and component studies for existing and possible future accelerator applications. This includes studies for high gradient acceleration methods, e.g. for CLIC and plasma technology, and prototyping and validation of accelerator components, e.g. for the HL-LHC upgrade. The facility also provides irradiation test capabilities for characterisation of electronic components and for medical applications. A description of the facility with details on the achievable beam parameters, and the status and plans are presented.
