• S. Boucher, P. Frigola, A.Y. Murokh
  RadiaBeam, Marina del Rey
• I. Jovanovic
  Purdue University, West Lafayette, Indiana
• J.B. Rosenzweig, G. Travish
  UCLA, Los Angeles, California

Funding: This work is supported by the US Defense Threat Reduction Agency SBIR contract HDTRA1-08-P-0035.

Conventional X-ray sources used for medical and industrial imaging suffer from low spectral brightness, a factor which severely limits the image quality that can be obtained. X-ray sources based on Inverse Compton Scattering (ICS) hold promise to greatly improve the brightness of X-ray sources. While ICS sources have previously been demonstrated, and have produced high-peak brightness X-rays, so far experiments have produced low average flux, which limits their use for certain important commercial applications (e.g. medical imaging). RadiaBeam Technologies is currently developing a high peak- and average-brightness ICS source, which implements a number of improvements to increase the interaction repetition rate, as well as the efficiency and stability of the ICS interaction itself. In this paper, we will describe these improvements, as well as plans for future experiments.

• S. Boucher, R.B. Agustsson, P. Frigola, A.Y. Murokh, M. Ruelas
  RadiaBeam, Marina del Rey
• F.H. O'Shea, J.B. Rosenzweig, G. Travish
  UCLA, Los Angeles, California

The fixed-field alternating-gradient (FFAG) betatron has emerged as a viable alternative to RF linacs as a source of high-energy radiation for industrial and security applications. RadiaBeam Technologies is currently developing an FFAG betatron with a novel induction core made with modern low-loss magnetic materials. The principle challenge in the project has been the design of the magnets. In this paper, we present the current status of the project, including results of the magnet design and testing.

• P. Frigola, R.B. Agustsson, S. Boucher, A.Y. Murokh
  RadiaBeam, Marina del Rey
• H. Badakov, A. Fukasawa, P. Musumeci, J.B. Rosenzweig, G. Travish
  UCLA, Los Angeles, California
• D. Cormier, T. Mahale
  NCSU, Raleigh, North Carolina
• L. Faillace
  INFN/LNF, Frascati (Roma)

Electron beam based additive fabrication techniques have been successfully applied to produce a variety of complex, fully dense, metal structures. These methods, collectively known as Solid Freeform Fabrication (SFF) are now being explored for use in radio frequency (RF) structures. SFF technology may make it possible to design and produce near-netshape copper structures for the next generation of very high duty factor, high gradient RF photoinjectors. The SFF process discussed here, Arcam Electron Beam Melting (EBM), utilizes an electron beam to melt metal powder in a layer-by-layer fashion. The additive nature of the SFF process and its ability to produce fully dense parts are explored for the fabrication of internal cooling passages in RF photoinjectors. Following an initial feasibility study of the SFF process, we have fabricated a copper photocathode, suitable as a drop-in replacement for the UCLA 1.6 cell photoinjector, with internal cooling channels using SFF. Material analysis of the prototype cathode and new designs for a high duty factor photoinjector utilizing SFF technology will be presented.

• A.Y. Murokh, R.B. Agustsson, P. Frigola
  RadiaBeam, Marina del Rey
• V. Solovyov
  BNL, Upton, Long Island, New York

Funding: DOE

A High Temperature Superconducting Dysprosium Pole Undulator (HTS-DPU) is proposed to achieve an ultra-high peak field in a very short period undulator structure. This design utilizes the unique ferromagnetic properties of dysprosium (Dy) at liquid nitrogen temperature. The fabrication of textured Dy fabricated via economic and highly reproducible process is studied experimentally with the goal to achieve sufficient magnetic anisotropy and desired field saturation level at a practical cost. In addition, utilizing the latest capabilities of the 2G HTS wire is investigated. The practical implementation of HTS-DPU would enable the development of short period insertion devices with superior performance.

• G. Andonian, S. Boucher, A.Y. Murokh, M. Ruelas
  RadiaBeam, Marina del Rey
• D. Dooley, S. Levingston, M. Stout
  Spectrum Detector, Lake Oswego, Oregon
• U. Happek
  UGA, Athens, Georgia
• G. Travish
  UCLA, Los Angeles, California

Funding: Work supported by U.S. DOE Grant Number DE-FG02-07ER84814.

The generation of high peak current, high brightness beams routinely requires compression methods (e.g. four-bend chicane), which produce coherent radiation as a by-product. The sensing of this radiation, coupled with interferometric methods, yields crucial longitudinal bunch length and bunch profile information. This paper discusses the progress of the development of a real-time terahertz interferometer used for longitudinal beam profile diagnosis.

• A.Y. Murokh
  RadiaBeam, Marina del Rey
• E. Hemsing, J.B. Rosenzweig
  UCLA, Los Angeles, California

A Coherent Optical Transition Radiation (COTR) arising from the photo-injector electron beams spontaneous microbunching at optical frequencies has been recently observed in a number of experiments. This effect can lead to an undesirable optical background for OTR beam profile measurements at these facilities. A method to resolve this problem is proposed, based on selectively suppressing the back-scattered COTR using multiple scattering in the insertion foil. An analytical treatment of COTR dependence on the angular divergence in the radiating beam is presented, and the efficacy of the approach is illustrated with the numerical examples.

• R. Tikhoplav, G. Travish
  UCLA, Los Angeles, California
• G. Andonian, A.Y. Murokh, M. Ruelas
  RadiaBeam, Marina del Rey
• T.V. Shaftan, V. Solovyov
  BNL, Upton, Long Island, New York

Funding: NSF grant # IIP-0724505

We describe our effort in the development of a low cost, wide-band detector/camera for generation of spatially resolved images of radiation beams in a multi-spectral range of wavelengths, from IR (infrared) to THz (terahertz). The detector (T-camera) utilizes a TLC (thermochromic liquid crystal) film as the sensitive element in a temperature controlled chamber and a CCD detector array and can be used as a powerful diagnostic for terahertz sources such as a synchrotron or an FEL

• M.P. Dunning, G. Andonian, A.M. Cook, E. Hemsing, A.Y. Murokh, S. Reiche, J.B. Rosenzweig, D. Schiller
  UCLA, Los Angeles, California
• M. Babzien, K. Kusche, V. Yakimenko
  BNL, Upton, Long Island, New York

Coherent radiation emitted by relativistic electron bunches traversing the edge regions of dipole magnets in a chicane bunch compressor was extracted and transported for measurement, using a dedicated terahertz beamline at the Accelerator Test Facility (ATF) at Brookhaven National Laboratory (BNL). Measurements include frequency spectrum and polarization of the radiation. The measurements are compared to predictions from QUINDI, a new simulation code developed at UCLA to model radiation emitted by charged particles in bending systems. Simulations and measurements indicate that because of interference of radiation from the two magnet edges, the edge radiation is suppressed at long wavelengths. In addition to being a source of broadband terahertz radiation, the system is also used as a non-invasive, single-shot, relative bunch length diagnostic to monitor compression in the chicane.