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At the CERN Large Hadron Collider (LHC), among the different systems exploiting Synchrotron Radiation (SR) for beam diagnostics, interferometry is under study as a non-invasive technique for measuring absolute beam transverse sizes. Extensive numerical simulations, recently completed for characterising the spatial coherence of the LHC SR source, facilitated the optimisation of the LHC interferometer design and the existing prototype system tested in the past has been refurbished to include the new simulation findings. This contribution describes the simulation specificity and then focuses on first measurements performed at the beginning of the LHC run 3. Such experiments allowed to obtain a first validation of the expected system performance at the injection energy of 450 GeV. A complete benchmark of the simulations will be carried out in 2022 as soon as the LHC will reach its top energy of 6.8 TeV., Proceedings of the 11th International Beam Instrumentation Conference, IBIC2022, Kraków, Poland

In the framework of the LHC Injectors Upgrade (LIU) project, the Super Proton Synchrotron (SPS) accelerator at CERN is undergoing a profound upgrade including a new high-energy beam dump. The new Target Internal Dump Vertical Graphite (TIDVG#5) is designed to withstand an average dumped beam power as high as 235 kW to cope with the increased intensity and brightness of the LIU beams whose energies in the SPS range from 14 to 450 GeV. Considering such highly demanding specifications, the constant monitoring of the device���s status and the characteristics of the beams that are dumped to it is of utmost importance to guarantee an efficient operation with little or no limitations. While the former is ensured with several internal temperature sensors, a Beam Observation system based on a scintillating screen and a digital camera is installed to extract the profile of the beam dumped in TIDVG#5 for post mortem analysis. This paper describes the overall system that uses the BTV images to contribute to the safe and efficient operation of the SPS Beam Dump System (SBDS) and hence the accelerator., Proceedings of the 18th International Conference on Accelerator and Large Experimental Physics Control Systems, ICALEPCS2021, Shanghai, China

The Beam Rate of Neutrals (BRAN) is a monitor that provides a relative luminosity measurement for the four LHC experiments. BRANs are used during operations as a tool to find and optimise collision and to cross-check experiments luminosity monitors. While each LHC experiments is equipped with BRANs, in this contribution we will focus on the new monitors installed for ATLAS and CMS that will replace the current ageing gas chambers during LHC run 3. These will also serve as as prototypes for the future High Luminosity LHC monitors that will need to sustain an even higher collision rate. A description of the BRAN as well as the first results obtained during the LHC Run 3 start-up will be presented., Proceedings of the 11th International Beam Instrumentation Conference, IBIC2022, Kraków, Poland

As part of the LHC injector Upgrade (LIU), the CERN SPS is now equipped with a new Beam Dumping System (SBDS) designed to cope with the high power beams foreseen for the High Luminosity LHC (HL-LHC) era. Before reaching the dump, the proton beam (from 26 to 450 GeV) is vertically kicked and then diluted passing through a series of horizontal and vertical bumps. This prevents the dump damage, by reducing the power density per surface unit. The quality of each dump event must be recorded and verified and all parameters of the SBDS are logged and analysed from the so-called Post-Mortem dataset. An essential part of the verification is performed by a beam imaging system based on a Chromox screen imaged on a digital camera. The desired availability level (100%, to protect the dump) and the harsh radiation environment made the design extremely challenging. For example, it implied the need for a 17 m long optical line made of high-quality optical elements, a special camera shielding (to minimise single event upsets) and a generally careful design accounting for maintenance aspects, mainly related to expected high activation levels. After giving an overview of the whole imaging system design with details on the chosen layout and hardware, this paper will discuss the DAQ and SW architecture, including the automatic, on-line, image selection for validating every dump event. This will be complemented with experimental results demonstrating the performance and reliability achieved so far., Proceedings of the 10th International Beam Instrumentation Conference, IBIC2021, Pohang, Rep. of Korea

The extensive array of beam instrumentation with which the LHC is equipped has played a major role in its commissioning, rapid intensity ramp-up and safe and reliable operation. Much of this equipment will need consolidation by the time the LHC enters the High-Luminosity (HL) era, while the upgrade itself brings a number of new challenges. The installation of a completely new final focus system in the two high-luminosity LHC insertions implies the development of new beam position monitors to equip the upgraded quadrupole magnets. As well as replacing the 10 current beam position monitors, six additional beam position monitors will be added per interaction region, to further improve beam control at the collision point.

Many of the beam image systems at CERN are located in high radiation environments. In order to cope with this issue, VIDICON cameras are presently used but their production has been nowadays discontinued worldwide. The development of an alternative beam imaging system is described here, based on radiation tolerant optical fibre bundles. Such an optical line relays the image of a scintillating screen to a standard CMOS camera, located away from the high radiation zone. A prototype system based on a 10m long bundle with 10⁴ fibres has been tested in the TT2 transfer line at CERN. The light transmission is rather low, but is compensated by the sensitivity of the CMOS camera. The system had a field of view of 60 mm and a spatial resolution of ~1 mm. The radiation hardness of such a fiber bundle was tested at the IRMA-CEA facility in Saclay, France. The bundle was irradiated at a rate of 3.6 kGy/h for 8 consecutive day. The total integrated dose achieved was ~700 kGy, which corresponds to about ten years of operation at the beam imaging station with the highest radiation dose at CERN. While the light transmission was reduced by 50%, this is still adequate to provide acceptable images., Proceedings of the 10th Int. Particle Accelerator Conf., IPAC2019, Melbourne, Australia

Run 2 of the CERN Large Hadron Collider (LHC) was successfully completed on 10th December 2018, achieving largely all goals set in terms of luminosity production. Following the first two-year long shutdown and the re-commissioning in 2015 at 6.5 TeV, the beam performance was increased to reach a peak luminosity of more than twice the design value and a colliding beam time ratio of 50%. This was accomplished thanks to the increased beam brightness from the injector chain, the high machine availability and the performance enhancements made in the LHC for which some methods and tools, foreseen for the High Luminosity LHC (HL-LHC) were tested and deployed operationally. This contribution provides an overview of the operational aspects, main limitations and achievements for the proton Run 2., Proceedings of the 10th Int. Particle Accelerator Conf., IPAC2019, Melbourne, Australia

The Beam Gas Vertex detector (BGV) is an innovative beam profile monitor being developed as part of the High Luminosity LHC (HL-LHC) project at CERN. The goal is to continually measure the transverse beam size by reconstructing beam-gas interaction vertices using high precision tracking detectors. To confirm the feasibility of such a device, a demonstrator based on eight modules of scintillating fiber detectors has been constructed, installed in the LHC and operated for the past 3 years. It will be shown that using the BGV the average transverse beam size can be obtained with a statistical accuracy of better than 5µm (for a gaussian beam with a σ of 200µm). This precision is obtained with an integration time of less than one minute. In addition, the BGV measures the size of individual bunches with a statistical accuracy of better than 5% within 5 minutes. The results obtained from all the data gathered over the past 3 years will be presented and compared to measurements from other beam profile monitors. Some ideas for improvements for the final HL-LHC instrument will also be discussed., Proceedings of the 10th Int. Particle Accelerator Conf., IPAC2019, Melbourne, Australia

Recurrent beam dumps significantly perturbed the operation of the CERN LHC in the summer months of 2017, especially in August. These unexpected beam dumps were triggered by fast beam losses that built up in the cryogenic beam vacuum at the half-cell 16 left of LHC-IP2 and were detected either at that location but mainly in the collimation insertions. This contribution details the experimental observables (beam losses, coherent instabilities, heat load to cryogenic system, vacuum signals), the extent of the understanding of the beam loss and instability mechanisms and the mitigation steps and new settings that allowed recovering the luminosity performance of the LHC for the rest of the Run., Proceedings of the 9th Int. Particle Accelerator Conf., IPAC2018, Vancouver, BC, Canada

The availability of the LHC machine was adversely affected in 2017 by tens of beam aborts provoked by frequent loss events in one standard arc cell (16L2). In most of the cases, the dumps were triggered by concurrently developing fast beam instabilities leading to particle losses in the betatron cleaning insertion. Many of the events started with a distinct sub-millisecond loss peak comparable to regular dust particle events, which have been observed along all the LHC since the start-up. In contrast to regular dust events, persistent losses developed in cell 16L2 after the initial peaks which can possibly be explained by a phase transition of macroparticles to the gas phase. In this paper, we summarize the observed loss characteristics such as spatial loss pattern and time profiles measured by Beam Loss Monitors (ionization chambers). Based on the measurements, we estimate the energy deposition in macroparticles and reconstruct proton loss rates as well as the gas densities after the phase transition. Differences between regular dust events and events in 16L2 are highlighted and the ability to induce magnet quenches is discussed., Proceedings of the 9th Int. Particle Accelerator Conf., IPAC2018, Vancouver, BC, Canada

The Beam Gas Vertex (BGV) monitor is being developed as part of the High Luminosity LHC project with the aim of providing measurements with less than 5% error on the beam size with an integration time of 5 minutes. It will be the only instrument capable of non-invasive beam size measurement throughout the LHC acceleration cycle with high intensity physics beams. A prototype BGV monitor has been installed in the LHC since 2016. Particles emerging from beam-gas interactions are recorded by 2 planes of scintillating fibre detectors. Based on vertex reconstruction of the detected tracks, this monitor allows non-invasive measurement of beam profiles with bunch-by-bunch resolution. A dedicated computer farm performs track reconstruction and event analysis on-line so that real-time beam profile measurements can be provided. Data taken in 2016 and 2017 will be presented that demonstrate the power of the method., Proceedings of the 6th Int. Beam Instrumentation Conf., IBIC2017, Grand Rapids, MI, USA

During 2017, the Large Hadron Collider LHC delivered luminosity for different physics configuration in addtion to the nominal 6.5 TeV proton-proton run. About 18.5 days were dedicated to commission and to deliver special physics to the experiments. Condifurations with large beta-star of 19 m and 24 m were prepared for luminosity calibration with Van de Meer scans. A proton-proton run at 2.51 TeV took place during the last weeks of November to provide reference data for the heavy ion (Pb-Pb, p-Pb) collisions at the same equivalent nucleon energy . A very short (0.5 days) but effective ion run was scheduled where the LHC saw the first Xe beams collissions and delivered around 3 ub-1 to ATLAS and CMS. The run ended with a low event pile-up run at 6.5TeV. This contribution summarizes the operational aspects and delivered targets for the different configurations., Proceedings of the 9th Int. Particle Accelerator Conf., IPAC2018, Vancouver, BC, Canada

The Beam Synchrotron Radiation Telescope (BSRT) is routinely used for estimating the transverse beam size, pro'le and emittance in the LHC; quantities playing a crucial role in the optimisation of the luminosity levels required by the experiments. During the 2017 LHC run, the intensi'ed analog cameras used by this system to image the beam have been replaced by GigE digital cameras coupled to image intensi'ers. Preliminary tests revealed that the typically used sub-image rectangles of 128×128 pixels can be acquired at rates of up to 400 frames per second, more than 10 times faster than the previous acquisition rate. To address the increase in CPU workload for the image processing, new VME CPU cards (Intel 4 core/2.5GHz/8GB RAM) are envisaged to be installed (replacing the previous Intel Core 2 Duo/1.5GHz/1GB RAM). This paper focuses on the software changes proposed in order to take advantage of the multi-core capabilities of the new CPU for parallel computations. It will describe how beam profile calculations can be pipe-lined through a thread pool while ensuring that the CPU keeps up with the increased data rate. To conclude, an analysis of the system performance will be presented., Proceedings of the 16th Int. Conf. on Accelerator and Large Experimental Control Systems, ICALEPCS2017, Barcelona, Spain

In May 2017, the CERN Large Hadron Collider (LHC) restarted operations at 6.5 TeV using the Achromatic Telescopic Squeeze (ATS) scheme with a target beta-star of 40 cm in ATLAS and CMS. The number of bunches was progressively increased to a maximum of 2556 with emittances of 2.5 um. In August, several machine parameters had to be re-tuned to mitigate beam loss induced instabilities and maintain a steady increase of the instantaneous luminosity. The use of a novel beam type and filling pattern produced in the injectors, allowed filling the machine with very low emittance beam (1.5 um) achieving an equivalent luminosity with 1868 bunches. In September, the beta-star was further lowered to 30 cm (using, for the first time, the telescopic technique of the ATS) and the bunch intensity pushed to 1.25·10¹¹ protons. In the last 3 months of 2017, the LHC produced more than 500 pb-1 of integrated luminosity per day, delivering to each of the high luminosity experiments 50.6 fb-1, 10% above the 2017 target. A general overview of the operational aspects of the 2017 proton run will be presented., Proceedings of the 9th Int. Particle Accelerator Conf., IPAC2018, Vancouver, BC, Canada

This note summarises the measurements and observations performed during the LHC Machine Development concerning the injection and emittance preservation studies with BCMS beam.

A test coronagraph for the observation of beam halo has been installed in the Synchrotron radiation monitor line LHCB2 in 2015. This coronagraph is commissioned with LHC operation at 450GeV (injection energy). After some optical testing of the coronagraph with visible Synchrotron radiation in B2, we try to observe artificially-made beam halo. The beam halo of 10⁻³ order of magnitude against the beam core is excited by the kicker of the transverse damper. We have succeeded to observe a diffraction noise free image of beam halo. The effect of beam collimator is also observed. Reduction of beam halo intensity was found nicely proportional to the simultaneously-recorded beam loss., Proceedings of the 8th Int. Particle Accelerator Conf., IPAC2017, Copenhagen, Denmark

The CERN Large Hadron Collider is equipped with two Beam Synchrotron Radiation (BSR) systems, one per beam, used to monitor the transverse distribution of the beam, its longitudinal distribution and the abort gap population. During the 2015-2016 winter shut-down period, one of the two BSR systems was equipped with a prototype beam halo monitor, based on the coronagraph technique, classically used in astrophysics telescopes to measure the sun corona. The system design, as well as its optics, was inherited from the coronagraph used in the KEK Photon Factory with some modifications made in order to satisfy the LHC BSR source constraints. This project is in the framework of the HL-LHC project, for which there is the requirement to monitor the beam halo at the level of 10⁻⁶ of the core intensity. This first prototype has been designed as a demonstrator system aimed at resolving a halo-core contrast in the 10-3 to 10-4 range. After discussing the design of the LHC coronagraph and its technical implementation, this contribution presents the result of the first tests with beam and the planned system upgrades for 2017., Proceedings of the 5th Int. Beam Instrumentation Conf., IBIC2016, Barcelona, Spain

LHC operation restarted in 2015 after the first Long Shutdown, planning for a 4-year long run until the end of 2018 (called Run 2). The beam energy was fixed at 6.5 TeV. The year 2015 was dedicated to establishing operation at the high energy and with 25 ns beams, in order to prepare production for the following three years. The year 2016 was the first one dedicated to production, and it turned out to be a record-breaking year, in which the goals in both peak and integrated luminosities with proton-proton beams were achieved and surpassed. This paper revisits 2015 and 2016, shortly highlighting the main facts in the timelines, recalling the parameters that characterized luminosity production, and sketching the main limitations and the main highlights of results for selected topics, including a particular focus on the beam physics issues., Proceedings of the North American Particle Accelerator Conf., NAPAC2016, Chicago, IL, USA

The High Intensity and Energy (HIE) upgrade to the on-line isotope separation facility (ISOLDE) facility at CERN is currently in the process of being commissioned. The very tight space available between the superconducting acceleration cavities and a challenging specification led to the design of a compact 'diagnostic box' with a number of insertable instruments on a common vacuum chamber. The box was conceived in partnership with the engineering firm AVS and produced as a completed assembly in industry. 14 diagnostic boxes have been installed and are now operational. This paper will describe the design, the construction and first results from operation of these HIE ISOLDE diagnostic boxes., Proceedings of the 5th Int. Beam Instrumentation Conf., IBIC2016, Barcelona, Spain

During the long LHC shutdown 2013-2014, both the LHC and its injector chain underwent significant upgrades. The most important changes concerned increasing the maximum LHC beam energy from 4TeV to 6.5TeV and reducing the transverse emittance of the beam from the LHC injectors. These upgrades pose challenges to the measurement of the transverse beam size via Synchrotron Radiation (SR) imaging, as the radiation parameters approach the diffraction limit. Optical SR interferometry, widely used in synchrotron light facilities, was considered as an alternative method to measure the 150 'm rms beam size at top energy as it allows measurements below the diffraction limit. A system based on this technique was therefore implemented in the LHC, for the first time on a proton machine. This paper describes the design of the LHC interferometer and its two SR sources (a superconducting undulator at low energy and a bending dipole at high energy), along with the expected performance in terms of beam size measurement as compared to the imaging system. The world's first proton beam interferogram measured at the LHC will be shown and plans to make this an operational monitor will be presented., Proceedings of the 5th Int. Beam Instrumentation Conf., IBIC2016, Barcelona, Spain

During the LHC long shut down in 2014, the transverse beam size diagnostics based on synchrotron radiation was upgraded in order to cope with the increase of the LHC beam energy to 6.5 TeV. The wavelength used for imaging was shifted to near ultra-violet to reduce the contribution of diffraction to the system resolution, while in parallel, a new diagnostic system based on double slit interferometry was installed to measure the beam size by studying the spatial coherence of the emitted synchrotron radiation. This method has never been implemented before in a proton machine. A Hartmann mask was also installed to identify possible wavefront distortions that could affect the system accuracy. This paper will focus on the comparison of visible and the near ultra-violet imaging and on the first experience with interferometry., Proceedings of the 7th Int. Particle Accelerator Conf., IPAC2016, Busan, Korea

During LHC Run 1 significant transverse emittance growth through the LHC cycle was observed. Measurements indicated most of the blow-up to occur during the injection plateau and the ramp. Intra beam scattering was one of the main drivers of emittance growth. However, finding a good wire scanner working point was difficult. Photomultiplier saturation added uncertainty on all measurements. A large discrepancy between emittances from wire scanners and luminosity was discovered but not solved. During Long Shutdown 1 the wire scanner system was upgraded with new photomultipliers. In April 2015 the LHC re-started with collision energy of 6.5 TeV per beam. This paper presents the first transverse emittance measurements through the LHC Run 2 cycle with low beam intensity. Comparisons with data from the synchrotron light monitors and the LHC experiments will be discussed and results summarized. In addition, a thorough study of wire scanner photomultiplier saturation will be presented. Finally, the emittance growth results will be compared to intra beam scattering simulations., Proceedings of the 4th International Beam Instrumentation Conference, IBIC2015, Melbourne, Australia

In the LHC, the beam halo due to higher beam energy and intensities will increase the impact on LHC machine protection and on luminosity performance. Measurement of the beam halo distribution is therefore important for understanding and controlling the beam halo. A coronagraph was designed for the observation of the beam halo population. A new optical design of the coronagraph is made for the halo observation in the LHC. For convenience of masking the core image, we need a large transverse magnification. For this purpose, a telephoto lens arrangement is applied to the adjective lens to extend the focal length to obtain a large transverse magnification. The result of diffraction analysis, the contrast is estimated better than 10⁶. Since the beam halo is estimated to 10⁴ -10⁵ of the core intensity, the coronagraph is estimated to have enough contrast for the observation of beam halo distribution at LHC. This paper describes the detail study of the coronagraph for the LHC for the observation of transverse profile of the beam halo with a contrast down to a level of 10⁻⁶ compared to the peak intensity of the beam core., Proceedings of the 4th International Beam Instrumentation Conference, IBIC2015, Melbourne, Australia

Interactions of high-energy beam particles with residual gas offer a unique opportunity to measure the beam profile in a non-intrusive fashion. Such a method was successfully pioneered* at the LHCb experiment using a silicon microstrip vertex detector. During the recent Large Hadron Collider shutdown at CERN, a demonstrator Beam-Gas Vertexing system based on eight scintillating-fibre modules was designed**, constructed and installed on Ring 2 to be operated as a pure beam diagnostics device. The detector signals are read out and collected with LHCb-type front-end electronics and a DAQ system consisting of a CPU farm. Tracks and vertices will be reconstructed to obtain a beam profile in real time. Here, first commissioning results are reported. The advantages and potential for future applications of this technique are discussed., Proceedings of the 7th Int. Particle Accelerator Conf., IPAC2016, Busan, Korea

For the High Luminosity upgrade the β* in IR1 and IR5 will be further reduced compared to the current LHC. As the β* decreases the β-functions in the inner triplet (IT) increase resulting in a higher sensitivity of the HL-LHC to ground motion in the IT region or to increases of the low frequency noise. Noise can in general lead to emittance growth and higher halo population and diffusion rate. However, it is usually assumed in the literature that only frequencies close to the betatron frequencies and sidebands have an effect on the emittance and tail population. To test this theory, an MD was carried out to observe if also low frequency noise can lead to emittance growth and stronger halo population and diffusion.

A laser-based profile monitor has been designed for commissioning of CERN's LINAC4 accelerator at 50 MeV and 100 MeV, as part of the development of a non-destructive profile and emittance monitor foreseen for the final 160 MeV beam. The system is based on a low power laser which is scanned through the H⁻ beam. Electrons, which are photo-detached from the ions by the laser, are deflected by a steerer magnet and measured by a diamond detector. The custom designed diamond detector is tailored to minimize the disturbance due to the electromagnetic field of the passing main beam. The laser source will be installed in the LINAC4 Klystron gallery located 75 m away from the profile station and an optical fiber will transport the laser to the tunnel. The laser propagation for different pulse length and peak power values was characterized with laboratory tests with such a long fiber. In this paper we describe the overall design, focusing on key elements such as the fiber-based laser transport and the electron detection with the diamond detector., Proceedings of the 4th International Beam Instrumentation Conference, IBIC2015, Melbourne, Australia

The AWAKE project at CERN is planned to study proton driven plasma wakefield acceleration. The proton beam from the SPS will be used in order to drive wakefields in a 10 m long Rb plasma cell. In the first phase of this experiment, scheduled in 2016, the self-modulation of the proton beam in the plasma will be studied in detail, while in the second phase an external electron beam will be injected into the plasma wakefield to probe the acceleration process. The installation of AWAKE in the former CNGS experimental area and the required optics flexibility define the tight boundary conditions to be fulfilled by the electron beam line design. The transport of low energy (10-20 MeV) bunches of 1.25·10⁹ electrons and the synchronous copropagation with much higher intensity proton bunches (3E11) determines several technological and operational challenges for the magnets and the beam diagnostics. The current status of the electron line layout and the associated equipments are presented in this paper., Proceedings of the 6th Int. Particle Accelerator Conf., IPAC2015, Richmond, VA, USA

Linac 4 presently under construction at CERN is designed to replace the existing 50 MeV Linac 2 in the LHC injector chain and will accelerate the beam of high current negative hydrogen ions to 160 MeV. During the commissioning a laserwire emittance scanner has been installed allowing noninvasive measuring of the emittance at 3 MeV and 12 MeV setups. A low power infrared fibre coupled laser was focused in the interaction region down to ~150 um and collided with the ion beam neutralising negative ions. At each transverse laser position with respect to the ion beam the angular distribution of the neutral particle beamlets was recorded by scanning a diamond detector across the beamlet at a certain distance from the IP while the main beam of the H⁻ ions was deflected using dipole magnet installed upstream the detector. Measuring the profile of the beamlet by scanning the laser across the beam allows to directly measure the transverse phase-space distribution and reconstruct the transverse beam emittance. In this report we will describe the analysis of the data collected during the 3 MeV and 12 MeV operation of the Linac 4. We will discuss the hardware status and future plans., Proceedings of the 6th Int. Particle Accelerator Conf., IPAC2015, Richmond, VA, USA

The extensive array of beam instrumentation with which the LHC is equipped, has played a major role in its commissioning, rapid intensity ramp-up and safe and reliable operation. High Luminosity LHC (HL-LHC) brings with it a number of new challenges in terms of instrumentation that will be discussed in this contribution. The beam loss system will need significant upgrades in order to be able to cope with the demands of HL-LHC, with cryogenic beam loss monitors under investigation for deployment in the new inner triplet magnets to distinguish between primary beam losses and collision debris. Radiation tolerant integrated circuits are also being developed to allow the front-end electronics to sit much closer to the detector. Upgrades to other existing systems are also envisaged; including the beam position measurement system in the interaction regions and the addition of a halo measurement capability to synchrotron light diagnostics. Additionally, several new diagnostic systems are under investigation, such as very high bandwidth pick-ups and a streak camera installation, both able to perform intra-bunch measurements of transverse position on a turn by turn basis., Proceedings of the 6th Int. Particle Accelerator Conf., IPAC2015, Richmond, VA, USA

The CERN PS Booster recombination lines (BT) will be upgraded following the extraction energy increase foreseen in 2018 and meant to reduce the direct space-charge tune shift in the PS injection for the future HL-LHC beams. Henceforth the main line elements, recombination septa, quadrupoles and dipoles must be scaled up to this energy. An increase in the beam rigidity by a factor 1.3 would require the same factor in the field integral of the septa, ∫Bdl, in order to bend the same angle and preserve the present recombination geometry, which is one of the main upgrade constraints. This paper describes the new optics, in particular in the new and longer septa. In addition we consider the upgrade of the so called BTM line that brings the beam to the external dump and where emittance measurements are taken thanks to three pairs of grids. The new proposed optics has also the advantage to simplify the design of the new dipoles. Here we study this new optics and the issues related to the emittance measurement at the new higher energy.

The Beam Gas Vertex detector (BGV) is an innovative beam profile monitor based on the reconstruction of beam-gas interaction vertices which is being developed as part of the High Luminosity LHC project. Tracks are identified using several planes of scintillating fibres, located outside the beam vacuum chamber and perpendicular to the beam axis. The gas pressure in the interaction volume is adjusted such as to provide an adequate trigger rate, without disturbing the beam. A BGV demonstrator monitoring one of the two LHC beams was fully installed and commissioned in 2016. First data and beam size measurements show that the complete detector and data acquisition system is operating as expected. The BGV operating parameters are now being optimised and the reconstruction algorithms developed to produce accurate and fast reconstruction on a CPU farm in order to provide real time beam profile measurements to the LHC operators., Proceedings of the 8th Int. Particle Accelerator Conf., IPAC2017, Copenhagen, Denmark

At the Large Hadron Collider (LHC) at CERN, synchrotron radiation (SR) is used to continuously monitor the transverse properties of the beams. Unfortunately the machine and beam parameters are such that the useful radiation emitted inside a separation dipole, chosen as source, is diffraction limited affecting heavily the accuracy of the measurement. In order to deconvolve the diffraction effects from the acquired beam images and in order to design an alternative monitor based on a double slit interferometer an extensive study of the synchrotron light source and of the optical propagation has been made. This study is based on simulations combining together several existing tools: SRW for the source, ZEMAX for the transport and MATLAB for the "glue" and analysis of the results. The resulting tool is very powerful and can be easily adapted to other synchrotron radiation problems. In this paper the simulation package and the way it is used will be described as well as the results obtained for the LHC and SPS cases., Proceedings of the 5th Int. Particle Accelerator Conf., IPAC2014, Dresden, Germany

The CERN LINAC4 beam commissioning at 3 and 12 MeV was completed in 2014. A novel system for measuring the transverse beam profile and emittance, based on low power laser stripping and H⁰ detection using a diamond detector, was successfully tested at these two energies. The measurement results agree with the operational slit-grid method within a few percent in terms of both transverse profile and emittance. After describing the general system setup, this remarkable achievement is discussed in detail together with the present limitations, which will be addressed in order to design a laser based emittance monitor for the LINAC4 top energy of 160 MeV.

The HIE-ISOLDE project aims at increasing the energy of the radioactive beams (RIB) of REX-ISOLDE from the present 3 MeV/u up to 10 MeV/u for A/q up to 4.5. This will be accomplished by means of a new superconducting linac, based on independently phased quarter wave resonators using the Nb sputtering on copper technology, and working at 101.28 MHz. The focusing elements are superconducting solenoids providing 13.5 T2m field integral. These active elements are contained in a common vacuum cryostat. The presentation will cover the status of advancement of the HIE-ISOLDE linac technical systems. The performance of the superconducting elements will be presented, together with the assembly work of the cryomodule in clean room and the planned qualification tests in the horizontal test facility at CERN

Beam profile monitoring of low intensity keV ion and antiproton beams remains a challenging task. A Sec- ondary electron Emission Monitor (SEM) has been de- signed to measure profiles of beams with intensities below 107 and energies as low as 20 keV. The monitor is based on a two stage microchannel plate (MCP) and a phosphor screen facing a CCD camera. Its modular design allows two different operational setups. In this contribution we present the design of a prototype and discuss results from measurements with antiprotons at the AEgIS experiment at CERN. This is then used for a characterization of the monitor with regard to its possible future use at different facilities.

We propose a new segmented beam dump to be installed in thespectrometer line at the end of the CTF3 linac. The device will allowfor time-resolved energy distribution measurements in a single shotand would therefore be a useful tool in tuning the accelerator. CLIC

LINAC4 is the first step in the upgrade of the injector chain for the LHC and will accelerate H⁻ ions to 160 MeV. The ion source has initially been installed in a laboratory setup where its commissioning started at the end of 2009. A slit-grid system is used to monitor the transverse emittance at the exit of the source. Measurement results have been compared to analytical and numerical predictions of the system performance, addressing the system resolution, accuracy and sensitivity. This information has been used to improve the design of a new slit-grid system required for commissioning the linac at higher energies., Proceedings of the 1st International Particle Accelerator Conference, IPAC2010, Kyoto, Japan

The LHC beam dump system relies on extraction kickers that need 3 microseconds to rise up to their nominal field. As a consequence, particles crossing the kickers during this rise time will not be dumped properly. The proton population during this time should remain below quench and damage limits at all times. A specific monitor has been designed to measure the particle population in this gap. It is based on the detection of Synchrotron radiation using a gated photomultiplier. Since the quench and damage limits change with the beam energy, the acceptable population in the abort gap and the settings of the monitor must be adapted accordingly. This paper presents the design of the monitor, the calibration procedure and the detector performance with beam., Proceedings of the 1st International Particle Accelerator Conference, IPAC2010, Kyoto, Japan

As part of the CERN LHC injector chain upgrade, LINAC4 will accelerate H⁻ ions from 45 keV to 160 MeV. A movable diagnostics test bench will be used to measure the beam parameters during the different construction stages (at 45 keV, 3 MeV and 12 MeV) at first in a laboratory setup and later in the LINAC4 tunnel. Given the beam properties at 3 and 12 MeV, the existing slit-grid system developed for the measurement of the transverse emittance at the source (45 keV) cannot be reused at these higher energies. At 3MeV and above the energy deposition would damage the steel slit in a single LINAC4 pulse. For this reason a new slit has been designed following detailed analytical and numerical simulations for different materials and geometries. The energy deposition patterns as simulated by FLUKA for the different cases are presented in detail. In addition, the choice of SEM grid wires for achieving the required measurement accuracy in terms of material, diameter and spacing, are discussed., Proceedings of the 1st International Particle Accelerator Conference, IPAC2010, Kyoto, Japan

On the Large Hadron Collider (LHC), the continuous monitoring of the transverse sizes of the beams relies on the use of synchrotron radiation and intensified video cameras. Depending on the beam energy different synchrotron light sources must be used. A dedicated superconducting undulator has been built for low beam energies (450 GeV to 3 TeV), while edge and centre radiation from a beam separation dipole magnet are used respectively for intermediate and high energies (up to 7 TeV). The emitted visible photons are collected using a retractable mirror, which sends the light into an optical system adapted for acquisition using intensified CCD cameras. This paper presents the performance of the imaging system in terms of spatial resolution, and comments on the light intensity obtained and the cross calibration performed with the wire scanners. Upgrades and future plans are also discussed., Proceedings of the 1st International Particle Accelerator Conference, IPAC2010, Kyoto, Japan

A set of different beam instruments have been developed and installed on LHC to provide transverse profile monitoring. Imaging systems using intercepting screens are currently used in the transfer lines from SPS, in the dump lines and in the LHC injection regions. Betatron matching oscillations would be investigated using Optical Transition Radiation screens and fast framing cameras, installed in Point 4. Wire scanners, provide high-resolution profile measurements from injection to top beam energies, but they cannot handle the full beam intensity. Thus, for continuous beam imaging as well as abort gap monitoring, synchrotron light monitors have been developed and installed. This paper gives a brief description of the different systems and presents the first results obtained during the beam commissioning in 2009.

In future high intensity, high energy accelerators particle losses must be minimized as activation of the vacuum chambers or other components makes maintenance and upgrade work time consuming and costly. It is imperative to have a clear understanding of the mechanisms that can lead to halo formation, and to have the possibility to test available theoretical models with an adequate experimental setup. Measurements based on optical transition radiation (OTR) provide an interesting opportunity for analyzing the transverse beam profile due to the fast time response and very good linearity of the signal with respect to the beam intensity. On the other hand, the dynamic range of typical acquisition systems as they are used in the CLIC test facility (CTF3) is typically limited and must be improved before these systems can be applied to halo measurements. One possibility for high dynamic range measurements is an innovative camera system based on charge injection device (CID) technology. With possible future measurements in CTF3 in mind, comparative measurements performed with this innovative camera system, a standard CCD camera and a step-by-step measurement technique based on a small photomultiplier are summarized with emphasis

This specification, drawn up by the instrumentation specification board 2, describes the requirements concerning orbit and trajectory measurements in the PS machine. The orbit measurement and the trajectory measurement are both indispensable in order to be able to guarantee the correct beam quality for beams like LHC, the future Grand Sasso beam, the nTOF beam and surely the combined operation of the nTOF beam and the East Area beam.

In high intensity accelerators, the knowledge of the beam halo distribution and its generation mechanisms are important issues. In order to study these phenomena, dedicated beam diagnostics must be foreseen. In circular machines, beam halo is monitored by using scrapers and beam loss detectors. In the framework of the CLIC project, a beam halo monitor is currently under development. The proposed device is based on an imaging system and a masking technique, which suppresses the core of the beam to allow direct observation of the halo. A first test was performed on the CLIC Test Facility 3 in 2003. We discuss the performances and the limitations of this technique pointing out our plans for future developments.

The development of segmented beam profile monitors, like wire grids, segmented photo tubes etc., require the optimisation of several detector parameters like; the size of the active area, the number of channels and the integration time. The influence of some of these parameters can be calculated by means of montecarlo simulations. In this paper the influence of these parameters on the measurement error is investigated by mean of numerical simulations.