In this paper, the measurements of vertical and horizontal aperture which are available for stable beam motion in Indus-2 at beam energy 2.5 GeV using movable beam scrapers are presented. These beam scrapers are installed in one of the long straight sections in the ring. With the movement of beam scrapers towards the beam centre, the beam lifetime is measured. The beam lifetime data obtained from the movement of vertical and horizontal beam scrapers are analyzed. The contribution of beam loss due to beam-gas scattering (vacuum lifetime) and electron-electron scattering within a beam bunch (Touschek lifetime) is separated from the measured beam lifetime at different positions of the beam scrapers. Vertical and horizontal beam sizes at scrapers location are estimated from the scraper movement towards the beam centre in quantum lifetime limit and their values closely agree with measured value obtained using X-ray diagnostic beamline.
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http://dx.doi.org/10.1063/1.4833395 | DOI Listing |
PLoS One
April 2024
Laboratory of Archaeology of Africa & Anthropology (ARCAN), University of Geneva, Genève, Switzerland.
The understanding of cultural dynamics at work at the end of the Final Pleistocene in West Africa suffers from a significant lack of excavated and dated sites, particularly in the Sahelian and Sudanian ecozones. While the Later Stone Age shows varied behavioral developments in different parts of the continent, the chrono-cultural framework of this period remains largely unknown in West Africa. We report on archaeological, geomorphological, and chronological research on two Final Pleistocene Later Stone Age sites in the Falémé Valley, eastern Senegal.
View Article and Find Full Text PDFMed Phys
July 2023
Department of Radiation Oncology, Mayo Clinic, Rochester, Minnesota, USA.
Background And Purpose: Proton therapy is a key modality used in the treatment of ocular melanoma. Traditionally ocular sites are treated using a dedicated eyeline with a passively scattered proton beam and a brass aperture. This work aims to design and characterize a beam-collimating aperture to treat ocular targets with a gantry-based spot scanning proton beam.
View Article and Find Full Text PDFDue to the existence of the expanding beam portion in the positive branch confocal unstable resonator, the laser passes through the intracavity deformable mirror (DM) twice with different apertures, which makes it complicated to calculate the required compensation surface of the DM. In this paper, an adaptive compensation method for intracavity aberrations based on reconstruction matrix optimization is proposed to solve this problem. A collimated probe laser of 976 nm and a Shack-Hartmann wavefront sensor (SHWFS) are introduced from the outside of the resonator to detect intracavity aberrations.
View Article and Find Full Text PDFRadiat Oncol
August 2016
Department of Transdisciplinary Studies, Program in Biomedical Radiation Sciences, Seoul National University Graduate School of Convergence Science and Technology, Seoul, 151-742, Korea.
Background: For breast cancer patients who require electron boost energies between 6 and 9 MeV, an energy degraders (ED) in the 9 MeV beamline was specially designed and manufactured to increase the skin dose of 6 MeV and to reduce the penetration depth of 9 MeV beams.
Methods: We used Monte Carlo (MC) techniques as a guide in the design of ED for use with linear accelerators. In order to satisfy percent depth dose (PDD) characteristics and dose profile uniformity in water, the shape and thickness of Lucite® ED in the 9 MeV beamline was iteratively optimized and then manufactured.
Purpose: The aims of this study were to investigate the best two of five common methods of collecting autologous bone (preliminary study [PS]) and to test clinically the effects of autografts harvested using a trephine bur or bone scraper for sinus augmentation surgery (main study [MS]).
Materials And Methods: In the PS, five autograft samples from five patients (n = 25) were harvested with a bone scraper, round bur, piezoelectric device, implant bur, and trephine bur and were processed for histomorphometric analysis. In the MS, sinus augmentation was performed on 20 patients using bovine-derived bone substitute and autograft collected with a trephine bur (group A, n = 10) or collected with a bone scraper (group B, n = 10).
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