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| MOPEA025 | Closed Orbit Correction in the High Field Lattice of ILSF Storage Ring | storage-ring, lattice, dipole, sextupole | 127 |
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| In the high intensity storage rings, there are many sources of errors which lead to closed orbit distortion (COD). To study effect of errors on closed orbit and to find optimum arrangement of beam position monitors (BPMs) and strength of corrector magnets, different types of expected misalignments and field errors were imposed randomly in the high field lattice of ILSF storage ring. This paper gives the results of closed orbit correction in the ILSF ring and stipulates the strength of correctors. | |||
| MOPME006 | The New Orbit Correction System at ELSA | polarization, electron, acceleration, extraction | 479 |
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| ELSA is a fast ramping stretcher ring currently supplying polarized electrons with energies up to 2.4 GeV. To preserve the degree of polarization, the vertical orbit needs to be continuously corrected during beam acceleration. The acceleration is usually performed within 300 ms, with a maximum ramping speed of 6 GeV/s. We aim to achieve a vertical rms deviation not exceeding 50 μm all along the fast energy ramp. In the near future we plan to accelerate polarized electrons up to 3.2 GeV. Therefore, both the power supplies and the corrector magnets have been currently upgraded: first, new power supplies working with a pulsed transistor H-Bridge were developed and successfully installed. Additionally, the existing vertical corrector magnets will now be replaced by newly developed ones. In our contribution, we will present the new correction hardware supplemented by the beam position monitors and their readout electronics. | |||
| MOPWO087 | Parameter Estimation of the Exponentially Damped Sinusoid for Noisy Signals | neutron, damping, feedback, synchrotron | 1079 |
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Funding: ORNL/SNS is managed by UT-Battelle, LLC, for the U.S. Department of Energy under contract DE-AC05-00OR22725 The damped sinusoid equation is a common model for many scientific processes involving damped periodic signals. Here we present two methods for estimating the damped sinusoid parameters for noisy signals. Both methods are based upon an exact, closed form solution to fit the parameters for signals without noise, and they estimate the parameters for the noisy signals by the statistical maximum likelihood criterion. The first method relies on an optimizer to minimize the mean square signal error. The second method estimates the parameters by direct calculation and is suitable when the signal noise is small and the frequencies are sufficiently far from the integer and half integer values. |
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| TUPME028 | RF Orbit Separation for CPT-Test Experiment at VEPP-4M | electron, positron, betatron, beam-beam-effects | 1634 |
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Funding: This work was supported by the Ministry of Education and Science of the Russian federation and the Russian Foundation for Basis Research (grant 11-02-01422-a) In a special program of experiments which is under development in a background regime at the VEPP-4M storage ring we set an aim to realize a potential possibility to make the CPT invariance test with the accuracy better than 10-8. The test will be based on a precise comparison of the spin precession frequencies of simultaneously stored electrons and positrons. To exclude the presence of static electric fields increasing a systematic error we have developed and tested a special RF system driven at the half revolution frequency to subsitute for the electrostatic orbit separation system. The latter is needed for the electron and positron orbit separation at the parasitic interaction point where the beam-beam effects drastically cut the beam currents. |
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| TUPWO006 | Orbit Correction System at the Collector Ring | sextupole, quadrupole, optics, dipole | 1886 |
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| The CR is dedicated ring for cooling of hot beam coming either from the antiproton separator or SFRS. It is anticipated that the understanding and control of the beam orbits will be important for achieving low beam losses. We describe our plans for measuring and correcting the COD of the CR. The closed orbit of the CR, which is distorted due to magnets misalignments, can reduce the ring acceptance by factor of 2, if a special correction system is not applied. The system, which is developed for the CR should be periodically or manually invoked to correct the global closed orbit and used to adjust the orbit position at some point using local bump. BPM and corrector magnets, which are planned to be used at the CR, are described in this paper. SVD method is used to obtain the corrector strength or corrector factors in global or local orbit correction. | |||
| TUPWO048 | Understanding the Tune, Coupling, and Chromaticity Dependence of the LHC on Landau Octupole Powering | octupole, coupling, alignment, simulation | 1976 |
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| During the 2012 LHC run there were several observations of unexpectedly large shifts to the tune, chromaticity, and coupling which were correlated with changes in the powering of Landau octupoles (MO). Understanding the chromaticity dependence is of particular importance given it's influence on instabilities. This paper summarizes the observations and our attempts to-date to understand the relationship between Q, Q', c- and the MO powering. | |||
| TUPWO054 | Recent Results from the EMMA Experiment | acceleration, simulation, betatron, synchrotron | 1988 |
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| EMMA (Electron Model for Many Applications) is a prototype non-scaling electron FFAG hosted at Daresbury Laboratory. After a recent demonstration of acceleration in the serpentine channel, the injected EMMA beam was further studied. This entails the continuation of the exploration of the large transverse and longitudinal acceptance and the effects of slower integer tune crossing on the betatron amplitude. A single closed orbit correction that is effective at multiple momenta (and hence over a significant range in tune space) was implemented. A comparison with a detailed model based on measured field maps, and the experimental mapping of the machine by relating the initial and final phase space coordinates was also done. These recent results together with more practical improvements such as injection orbit matching with real-time monitoring of the coordinates in the transverse phase space will be reported in this paper. | |||
| TUPWO056 | Modelling of the EMMA ns-FFAG Ring using GPT | space-charge, simulation, electron, injection | 1994 |
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| EMMA (Electron Machine with Many Applications) is a prototype non-scaling Fixed-Field Alternating Gradient (ns-FFAG) accelerator whose construction at Daresbury Laboratory, UK, was completed in the autumn of 2010. The energy recovery linac ALICE serves as an injector for the EMMA ring, within an effective energy range of 10 to 20 MeV. The ring is composed of 42 cells, each containing one focusing and one defocusing quadrupole. Acceleration over many turns of the EMMA machine has recently been confirmed. In some cases the bunch will traverse upwards of 100 turns, at which point the effects of space-charge may be significant. It is therefore necessary to model the electron beam transport in the ring using a code capable of both calculating the effect of and compensating for space-charge. Therefore the General Particle Tracer (GPT) code has been used. A range of injection beam parameters have been modelled for comparison with experimental results and those of other codes. The simulated effects of space-charge on the tune shift of the machine are also compared with those expected from theory. | |||
| WEPEA003 | Dipole Fringe Field Effects in the ThomX Ring | dipole, quadrupole, sextupole, betatron | 2504 |
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| Thom-X is a 50 MeV compact ring based on the Compton back-scattering which is being built in LAL, France. With a very short bend radius of 0.352 m, the nonlinear effects of the dipole fringe fields become critical to the beam dynamic . This paper compares the modelings of the dipole fringe field using four popular codes: MadX, Elegant, BETA, and Tracy3, and then discuss the proper model to have consistent results between the analytical calculation and the symplectic tracking of the Thom-X ring. | |||
| WEPEA056 | Design and Beam Measurements of Modified Fast Extraction Schemes in the CERN PS for Installing a Dummy Septum to Mitigate Ring Irradiation | extraction, septum, kicker, emittance | 2633 |
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| The proposed Multi-Turn Extraction (MTE) for the CERN PS allows to reduce the overall extraction losses for high intensity beams. The required longitudinal structure of the proton beam induces unavoidable beam losses at the magnetic extraction septum. The installation of a dummy septum with an appropriate shielding has been proposed to localise losses and to shadow the magnetic septum. Such a device, located in the extraction region, imposes tight constraints on the available beam aperture. Modified extraction schemes have been proposed and in this paper they will be presented and discussed in detail together with the measured performance. | |||
| THPEA040 | Design of a Magnetic Bump Tail Scraping System for the CERN SPS | injection, beam-losses, extraction, radiation | 3228 |
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| The LHC injectors are being upgraded to meet the demanding beam specification required for High Luminosity LHC (HL-LHC) operation. In order to reduce the beam losses which can trigger the sensitive LHC beam loss interlocks during the SPS-to-LHC beam injection process, it is important that the beam tails are properly scraped away in the SPS. The current SPS tail cleaning system relies on a moveable scraper blade, with the positioning of the scraper adjusted over time according to the orbit variations of the SPS. A new robust beam tail cleaning system has been designed which will use a fixed scraper block towards which the beam will be moved by a local magnetic orbit bump. The design proposal is presented, together with the related beam dynamics studies and results from machine studies with beam. | |||