696 research outputs found
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
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
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
Evaluation of Psychometric and Linguistic Properties of the Italian Adolescent Pain Assessment Scales: A Systematic Review
Introduction: Adolescents’ pain experiences
are complex and multidimensional, and evaluating
pain only from a sensory and affective
point of view may be in many instances limiting
and inadequate; this is the reason why it is
of paramount importance to identify the tools
which can better assess the pain experienced by
young patients. A person-oriented approach is
highly encouraged, as it may better investigate
the cognitive and behavioral development typical
of this age group. The aim of this review
paper is to describe the available tools which are
able to adequately assess pain intensity in adolescents,
in particular those validated in Italian.
Methods: We conducted a systematic review
using four databases: CINAHL, PsycINFO,
PubMed and Cochrane, and selected all the
articles published between January 1970 and
November 2017. We selected all the papers
reporting the validation process of pain assessment
tools specifically tailored for adolescent
patients (age range 10–18 years) and based on
psychometric and linguistic parameters, and
focused especially on the tools available in
Italian and able to measure acute and chronic
pain.
Results: The results of our investigation have
revealed the existence of 40 eligible tools, 17 of
which are monodimensional and the remaining
23 multidimensional, more specifically tailored
to assess both acute and chronic pain. Some of
the instruments (26) were self-reports while
others were classified as behavioral (13) and/or
mixed. Only one tool turned out to be suitable
for fragile adolescents, while six adopted a
person-oriented approach that better emphasized
the cognitive and behavioral process typical
of the adolescent population. None of them
has ever been validated in Italian.
Conclusion: Valid and reliable psychometric
tools specifically organized to provide a cultural
and linguistic evaluation of the patient are
indeed the most recommended instruments to
assess the intensity of the pain experienced by
the patient, as they may provide useful information to implement a health policy
aimed at identifying the best assistance
programs
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
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