Beam Dynamics Studies for the CLIC Main Linac

The implications of long-range wakefields on the beam quality are investigated through a detailed beam dynamics study. Injection offsets are considered and the resulting emittance dilution recorded, including systematic sources of error. These simulations have been conducted for damped and detuned structures (DDS) and for waveguide damped structures-both for the CLIC collider.Comment: 3 pages, 6 figures, IPAC1

Design Study of the CLIC Injector and Booster Linacs with the 2007 Beam Parameters

This note presents new particle tracking studies in the CLIC Injector and Booster Linacs, which accelerate both electrons and positrons, respectively from 200 MeV to 2.42 GeV, prior to their injection into the pre-damping rings, and from 2.42 to 9 GeV, before their transport to the main accelerating linacs

Alignment of the CLIC BDS

Aligning the CLIC Beam Delivery System faces two major challenges, the tight tolerances for the emittance preservation and its strong non-linear beam dynamics. For these reasons conventional beam-based alignment techniques, like dispersion free steering, are only partially successful and need to be followed by optimization algorithms based on other observables, like beam sizes

Bunch Compressor for Beam-Based Alignment

Misalignments in the main linac of future linear colliders can lead to significant emittance growth. Beam-based alignment algorithms, such as Dispersion Free Steering (DFS), are necessary to mitigate these effects. We study how to use the Bunch Compressor to create the off-energy beams necessary for DFS and discuss the effectiveness of this method

Beam Dynamics Studies in the CLIC Injector Linac

The CLIC Injector Linac has to accelerate both electron and positron main beams from 200 MeV up to 2.42 GeV prior to their injection into the pre-damping rings. Its 26 accelerating structures operate at 1.5 GHz, with a loaded gradient of 17 MV/m. A FODO lattice that wraps the accelerating structures at the beginning of the linac, followed by a succession of triplet lattices between the accelerating structures, is proposed. The large normalized transverse emittance (9200 mm.mrad rms), bunch length (5mmrms) and energy spread (7 MeV rms) of the e+ beam set constraints on the linac, in order to reach acceptable characteristics at 2.42 GeV for the injection into the predamping ring. The use of a bunch compressor at the linac entrance is an option in order to achieve good performance in both the longitudinal and transverse phase spaces. Tracking studies of both electron and positron beams in the linac have been performed and are presented

Benchmarking of the Placet and Dimad tracking codes using the CLIC Post-Collision line

In this benchmarking study, two contemporary codes, DIMAD and PLACET, are compared. We consider the 20 mrad post-collision line of the Compact Linear Collider (CLIC) and perform tracking studies of heavily disrupted post-collision electron beams. We successfully find that the two codes provide an equivalent description of the beam transport from the interaction point to the final dump

A primary electron beam facility at CERN

This paper describes the concept of a primary electron beam facility at CERN, to be used for dark gauge force and light dark matter searches. The electron beam is produced in three stages: A Linac accelerates electrons from a photo-cathode up to 3.5 GeV. This beam is injected into the Super Proton Synchrotron, SPS, and accelerated up to a maximum energy of 16 GeV. Finally, the accelerated beam is slowly extracted to an experiment, possibly followed by a fast dump of the remaining electrons to another beamline. The beam parameters are optimized using the requirements of the Light Dark Matter eXperiment (LDMX) as benchmark.Comment: 3 pages, 3 figure

Long-term safety and efficacy of selective laser trabeculoplasty as primary therapy for the treatment of pseudoexfoliation glaucoma compared with primary open-angle glaucoma

Tarek A Shazly1,2, Jan Smith3, Mark A Latina41Ophthalmology Department, Massachusetts Eye and Ear Infirmary, Harvard Medical School, Boston, MA, USA; 2Ophthalmology, Assiut University Hospital, Assiut, Egypt; 3Oslo Eye Institute, Oslo, Norway; 4Reading Health Center, Reading, MA, USAPurpose: To investigate the safety and efficacy of selective laser trabeculoplasty (SLT) to reduce intraocular pressure (IOP) in patients with pseudoexfoliation glaucoma (PXFG) compared with primary open-angle glaucoma (POAG).Design: Non-randomized, prospective, clinical trial.Methods: Nineteen eyes of 13 patients with POAG and 18 eyes of 13 patients with PXFG were treated with SLT. Patients were followed without antiglaucoma medications until additional medical, laser, or surgical intervention was initiated, at which time they were considered failures, had withdrawn from the study, or underwent a second SLT.Results: The POAG and PXFG eyes showed similar reductions of IOP over the 49 months of follow-up. At 30 months of follow-up the POAG group showed a mean IOP of 17.6 ± 2.8 mmHg and a mean IOP reduction of 5.7 ± 2.1 mmHg; the PXFG group showed a mean IOP of 18.3 ± 4.7 and a mean IOP reduction of 5.3 ± 3.0 mmHg. Four eyes in the PXFG group and three eyes in the POAG group failed by 30 months. The cumulative probability of success was 74% for the PXFG group and 77% for the POAG group. Four PXFG eyes underwent a second SLT after 30 months of follow-up with a final IOP of 17.6 ± 2.8 mmHg. There were no serious adverse events.Conclusion: SLT is a safe and effective method to lower IOP in patients with PXFG as initial glaucoma therapy. Both groups showed similar IOP reductions and failure rates.Keywords: glaucoma, selective laser trabeculoplasty, primary open angle glaucoma, pseudoexfoliation glaucoma, intraocular pressure, laser, trabecular meshwor

CLIC Main beam dynamics in the ring to main LINAC transport

Prior to acceleration in the main linac, the particle beams created in the centrally located injector have to be transported to the outer ends of the CLIC site. This transport should not only preserve the beam quality but also shape, characterize and tune the phase space distribution to match the requirements at the entrance of the main linac. Hence, the performance of the transport downstream of the damping rings up to the main linac, the so called RTML, is crucial for the overall performance of CLIC. We discuss the different parts of the RTML and the occurring beam dynamics challenges. Their status is outlined and results of beam dynamics simulations are presented

Feedback Studies

Dynamic imperfections in future linear colliders can lead to a significant luminosity loss. We discuss different orbit feedback strategies in the main linac that can mitigate the emittance dilution and compare their efficiency. We also address the impact of ground motion in the beam delivery system and the potential cures