Collimation of the multi-MW beams in present linear collider designs is a critical issue. Graphite as a possible collimator material exhibits good mechanical properties but a rather poor electrical conductivity. The resulting resistive wakefields can potentially deteriorate the beam quality. The knowledge of strength and scalings of such wakefields is essential for the design of the collimation...

We present a direct measurement of the short-range wakefield of a series of tapered collimators. The wakefields were measured by inserting a fixed aperture in the path of the electron beam at the 1.19 GeV point of the SLAC linac. As the vertical position of the collimator is varied, the vertical deflection of the beam is measured on 29 downstream beam position monitors. A series of apertures wi...

Helical tomotherapy has been developed at the University of Wisconsin, and 'Hi-Art II' clinical machines are now commercially manufactured. At the core of each machine lies a ring-gantry-mounted short linear accelerator which generates x-rays that are collimated into a fan beam of intensity-modulated radiation by a binary multileaf, the modulation being variable with gantry angle. Patients are ...

In 2014 a new vertical flight path was installed at the neutron time-of-flight facility, n TOF, at CERN. The beam line optimization of this second experimental area (EAR2) was performed by FLUKA simulations with a detailed model of the facility, including the spallation target, neutron beam line, magnet, collimators and beam dump. The beam profile as well as neutron and gamma fluxes were calcul...

We derive formulae for the coherent and incoherent tune shift due to the nonlinear resistive-wall wake field for a single beam travelling between two parallel plates. The theoretical predictions are compared with measurements performed on an LHC prototype collimator during the 2004 SPS run. We show that the tune shift derived from the nonlinear wake field yields a better agreement with the meas...

A prototype scanning-laser fan beam optical CT scanner is reported which is capable of high resolution, large volume dosimetry with reasonable scan time. An acylindrical, asymmetric aquarium design is presented which serves to 1) generate parallel-beam scan geometry, 2) focus light towards a small acceptance angle detector, and 3) avoid interference fringe-related artifacts. Preliminary experim...

Based on the fan-beam reconstruction formula recently developed by Noo et al. [Phys. Med. Biol. 47, 2525-2546 (2002)] we develop a Feldkamp-type algorithm for the reconstruction of a volume of interest (VOI) from super-short-scan data. With either a circular or spiral scanning locus in our VOI reconstruction scheme, we first estimate fan-beam data from cone-beam data using the popular "cosine c...

Introduction: The head scatter factor (Sc) is important to measurements radiation beam and beam modeling of treatment planning systems used for advanced radiation therapy techniques. This study aimed to investigate the design of a mini-phantom to measurement variations in collimator Sc in the presence of shielding blocks for shaping the beam using different field sizes. <str...

The MInes NEutron Radiography (MINER) facility provides students and researchers at the Colorado School of Mines with the capability to perform neutron imaging at the Geological Survey TRIGA Reactor (GSTR). The current beamline consists of a 1.5 inch innerdiameter aluminum pipe routed from the reactor up to an experiment station in the reactor bay. There are several limitations associated with ...