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| MOPMR024 | A Versatile Beam Loss Monitoring System for CLIC | 286 |
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| The design of a potential CLIC beam loss monitoring (BLM) system presents multiple challenges. To successfully cover the 48 km of beamline, ionisation chambers and optical fibre BLMs are under investigation. The former fulfils all CLIC requirements but would need more than 40000 monitors to protect the whole facility. For the latter, the capability of reconstructing the original loss position with a multi-bunch beam pulse and multiple loss locations still needs to be quantified. Two main sources of background for beam loss measurements are identified for CLIC. The two-beam accelerator scheme introduces so-called crosstalk, i.e. detection of losses originating in one beam line by the monitors protecting the other. Moreover, electrons emitted from the inner surface of RF cavities and boosted by the high RF gradients may produce signals in neighbouring BLMs, limiting their ability to detect real beam losses. This contribution presents the results of dedicated experiments performed in the CLIC Test Facility to quantify the position resolution of optical fibre BLMs in a multi-bunch, multi-loss scenario as well as the sensitivity limitations due to crosstalk and electron field emission. | ||
| DOI • | reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMR024 | |
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| MOPMR043 | Optical System Design for The ESS Proton Beam and Target Diagnostics | 347 |
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Funding: Science and Technology Facilities Council The high power and low emittance of the European Spallation Source (ESS) proton beam require a robust protection strategy for the spallation target and its surroundings. For this, the beam will be imaged on passing through scintillator screens coating both the proton beam window (PBW) on exit from the accelerator, and the entry window to the target (TW). Light from the screens must be transported to remote cameras through a 4m high shielding plug of limited aperture. At the same time, the optical path must not compromise the integrity of the shield against neutrons and interaction products. We present the theory underlying the design of the reflective optics for efficient transmission of high-quality images to provide the desired level of protection to the machine, and describe its implementation in the Zemax software tool, as well as the predicted imaging performance. We also consider how the requirements of environment (thermal and radiation), initial alignment and ongoing maintenance for the optical system will be met. Finally we comment on the applicability of optics of this type for diagnostic systems in similar situations at other neutron sources and elsewhere. |
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| DOI • | reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMR043 | |
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| MOPMR044 | Optimization of Particle Accelerators (oPAC) | 350 |
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Funding: This project has received funding from the European Union's Seventh Framework Programme for research, technological development and demonstration under grant agreement no 289485. The optimization of the performance of any particle accelerator critically depends on an in-depth understanding of the beam dynamics, powerful simulation tools and beam diagnostics, as well as a control and data acquisition system that links all the above. The oPAC consortium has carried out collaborative research into these areas, with the aim to optimize the performance of present and future accelerators that lie at the heart of many research infrastructures. The network brought together research centers, universities, and industry partners to jointly train 23 researchers in this interdisciplinary field. This contribution presents selected research highlights from the network's scientific work packages: results from beam dynamics simulations into upgrade scenarios for the LHC and the 3rd generation light sources ALBA and SOLEIL; use of a cryogenic current comparator for low intensity ion beams; advanced beam loss monitors operating in cryogenic environments; and a laser-wire beam profile monitor for H− beams. Finally, it discusses how an open source control system based on a relational database using a dynamic library loader can help enhance overall facility operation. |
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| DOI • | reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMR044 | |
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| MOPMR045 | High Resolution and Dynamic Range Characterisation of Beam Imaging Systems | 354 |
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Funding: Work supported by the EU under grant agreement 624890 and the STFC Cockcroft Institute core grant ST/G008248/1. Any imaging system requires the use of various optical components to transfer the light from the source, e.g. optical radiation generated by a charged particle beam, to the sensor. The impact of the transfer optics on the image resolution is often not well known. To improve this situation, the point spread function (PSF) of the optical system must be measured, preferably, with high dynamic range. For this purpose we have created an intense, small (~ 1 μm) point source using a high quality laser and special focusing optics; and introduced a digital micro-mirror array in the optical system to substantially increase its dynamic range. The PSFs of optical systems that are currently being developed for high resolution, high dynamic range beam imaging using optical transition and diffraction radiation are measured and compared to Zemax simulations. The goal of these studies is to systematically understand and mitigate any ill effects on the PSF due to aberrations, diffraction and misalignment of the components of the imaging system. We present the results of our measurements and simulations. |
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| DOI • | reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMR045 | |
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| MOPMR046 | Characterizing Supersonic Gas Jet-based Beam Profile Monitors | 357 |
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Funding: Work supported by EU under contracts 215080 and 289191, Helmholtz Association (VH-NG-328) and STFC under the Cockcroft Institute core grant ST/G008248/1. The next generation of high power, high intensity accelerators requires non-invasive diagnostics, particularly beam profile monitors. Residual gas-based diagnostics such as ionization beam profile or beam induced fluorescence monitors have been used to replace commonly used scintillating screens. At the Cockcroft Institute an alternative technique using a supersonic gas jet, shaped into a 45o curtain screen, was developed. It has already demonstrated its superior performance in terms of resolution and signal-to-noise ratio in comparison with residual gas monitors in experimental studies. The performance of this type of monitor depends on the achievable jet homogeneity and quality. Using a movable vacuum gauge as a scanner, the dynamic characteristics of the jet are studied. In this paper we also give an analysis of the resolution for this monitor in detail from the theory and ion drift simulation. |
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| DOI • | reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMR046 | |
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| MOPMR048 | Emittance Measurements and Operation Optimization for ECR Ion Sources | 361 |
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Funding: RIKEN IPA scheme and Cockcroft Institute Core Grant Electron Cyclotron Resonance (ECR) ion sources supply a broad range of ions for post acceleration in cyclotrons. Here, an effort to improve the beam transfer from RIKEN's 18 GHz ECR ion source to the Low Energy Beam Transfer (LEBT) line and an optimization of the performance of the ion source is presented. Simulation studies have shown that less than 20% of the beam is currently transferred. The first goal is to measure the transverse beam emittance in real time. The emittance monitor designed and fabricated for this purpose utilizes a pepper pot plate followed by a transparent scintillator and a CMOS camera for image capture. The second goal is to find the optimal operating point of the ion source by sweeping parameters such as RF power, vacuum pressure, extraction electrode position and voltage. To this extent, modifications of the ion source took place, as well as a measurement of the magnetic field inside the ion source. In this contribution the results of the emittance and other operating parameters measurements, as well as the design details of the emittance monitor are presented |
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| DOI • | reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMR048 | |
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| TUPOY026 | Optimization of Medical Accelerators | 1966 |
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Funding: This project has received funding from the European Union's Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No 675265. The Optimization of Medical Accelerators (OMA) is the aim of a new European Training Network. OMA joins universities, research centers and clinical facilities with industry partners to address the challenges in: treatment facility design and optimization; numerical simulations for the development of advanced treatment schemes; and beam imaging and treatment monitoring. Projects include: compact accelerators for proton beam energy boosting and gantry design; strategies for improving Monte Carlo codes for medical applications and treatment planning; and advanced diagnostics for online beam monitoring. The latter involves RF-based measurements of ultra-low charges and new encoding methodologies for ultra-fast 3D surface scanning. This contribution presents an overview of the network's research program and highlights the various challenges across the three scientific work packages. It also summarizes the network-wide training program consisting of schools, topical workshops and conferences that will be open to the wider medical and accelerator communities. |
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| DOI • | reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPOY026 | |
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| TUPOY027 | Beam Dynamics Studies into Grating-based Dielectric Laser-driven Accelerators | 1970 |
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Funding: Work supported by the EU under grant agreement 289191 and the STFC under the Cockcroft Institute core grant ST/G008248/1. Dielectric laser-driven accelerators (DLAs) based on gratings confine an electromagnetic field induced by a drive laser into a narrow vacuum channel where electrons travel and are accelerated. This can provide an alternative acceleration technology compared to conventional rf cavity accelerators. Due to the achievable high acceleration gradient of up to several GV/m this could pave the way for future ultra-short and low costμaccelerators. This contribution presents detailed beam dynamics simulations for multi-period double grating structures. Using the computer code VSim and realistic beam distributions, the achievable acceleration gradient and final beam quality in terms of emittance and energy spread are discussed. The results are then used for an overall optimization of the accelerating structure. |
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| DOI • | reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPOY027 | |
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| WEPOR052 | Emittance Measurements in Low Energy Storage Rings | 2788 |
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Funding: Work supported by the EU under grant agreement 624854 and the STFC Cockcroft Institute Core Grant No. ST/G008248/1. The development of the next generation of ultra-low energy antiproton and ion facilities requires precise information about the beam emittance to guarantee optimum performance. In the Extra-Low ENergy Antiproton storage ring (ELENA) the transverse emittances will be measured by scraping. However, this diagnostic measurements faces several challenges: non-zero dispersion and systematic errors due to diffusion processes, such as intra-beam scattering, and the speed of the scraper with respect to the beam revolution frequency. In addition, the beam distribution will likely be non-Gaussian. Here, we present algorithms to efficiently address the emittance reconstruction in presence of the above effects, and present simulation results for the case of ELENA. We also discuss the feasibility of using alternative non-invasive techniques for profile and emittance measurements. |
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| DOI • | reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPOR052 | |
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| THPMY042 | Laser Applications at Accelerators | 3751 |
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Funding: This project has received funding from the European Union's Seventh Framework Programme for research, technological development and demonstration under grant agreement no 289191. The LA3NET consortium has developed advanced laser applications for particle accelerators within an international research and training network. It brought together research centers, universities, and industry partners to carry out collaborative research into all the above areas and jointly train the next generation of researchers. This contribution presents selected research highlights from the LA3NET network. It shows how enhanced ionization schemes can provide better ion beams for radioactive beam facilities, and how RF photo injectors can produce high brightness electron beams. It also presents results from studies into ultra-compact, fiber optics-based electron accelerators and new radiation sources based on laser accelerated beams. Finally, it summarizes how electro-optical techniques, laser velocimeters, and laser emittance meters can all help characterize beams with better time and spatial resolution in non-invasive ways. |
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| DOI • | reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPMY042 | |
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| MOPMR039 | Review of Emittance Diagnostics for Space Charge Dominated Beams for AWAKE e- Injector | 337 |
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Funding: This work is supported by the Cockcroft Institute Core Grant and STFC. For a low energy, high intensity beam, total beam emittance is dominated by defocusing space charge force. This is most commonly observed in photo-injectors. In this low energy regime, emittance measurement techniques such as quadrupole scans fail as they consider the beam size only depends on optical functions. The pepper-pot method is used for 2D emittance measurements in a single shot manner. In order to measure the beam emittance in space charge dominated regime by quadrupole scans, space charge term should be carefully incorporated into the transfer matrices. On the other hand, methods such as divergence interferometry via optical transition radiation (OTRI), phase space tomography using 1D projections of quadrupole scans can be suitably applied for such conditions. In this paper, the design of a versatile pepper-pot system for AWAKE experiment at CERN is presented for a wide range of bunch charges from 0.1 to 1nC where the space charge force increases significantly. In addition, other aforementioned methods and respective algorithms are introduced as alternative methods. |
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| DOI • | reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMR039 | |
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