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This paper presents the design on the Cornell Electron Storage Ring (CESR) of an experimental set-up to meas-ure incoherent Diffraction Cherenkov Radiation (DChR) produced in a 2 cm long SiO2 radiator by a 2.1 GeV elec-tron beam. The electron beam is circulating at a distance of few mm from the edge of the radiator and the DChR photon output power is expected to be significantly higher than the diffraction radiation power emitted from a metal-lic slit of similar aperture. The radiator design and the detection set-up are presented in detail together with sim-ulations describing the expected properties of the emitted DChR in terms of light intensity and spectral bandwidth. Finally, potential applications of DChR are discussed., Proceedings of the 8th Int. Particle Accelerator Conf., IPAC2017, Copenhagen, Denmark

Beam observation systems, based on charged particles passing through a light emitting screen, are widely used and often crucial for the operation of particle accelerators as well as experimental beamlines. The AWAKE experiment, currently under construction at CERN, requires a detailed understanding of screen sensitivity and the associated accuracy of the beam size measurement. We present the measurement of relative light yield and screen resolution of seven different materials (Chromox, YAG, Alumina, Titanium, Aluminium, Aluminium and Silver coated Silicon). The Chromox and YAG samples were additionally measured with different thicknesses. The measurements were performed at the CERN's HiRadMat test facility with 440 GeV/c protons, a beam similar to the one foreseen for AWAKE. The experiment was performed in an air environment., Proceedings of the 5th Int. Beam Instrumentation Conf., IBIC2016, Barcelona, Spain

Optical systems are used to transfer light in beam diagnostics for a variety of imaging applications. The effect of the point spread function (PSF) of these optical systems on the resulting measurements is often approximated or misunderstood. It is imperative that the optical PSF is independently characterised, as this can severely impede the attainable resolution of a diagnostic measurement. A high quality laser and specially chosen optics have been used to generate an intense optical point source in order to accomplish such a characterisation. The point source was used to measure the PSFs of various electron-beam imaging systems. These systems incorporate a digital micro-mirror array, which was used to produce very high (>105) dynamic range images. The PSF was measured at each intermediary image plane of the optical system; enabling the origin of any perturbations to the PSF to be isolated and potentially mitigated. One of the characterised systems has been used for optical transition radiation (OTR) measurements of an electron beam at KEK-ATF2 (Tsukuba, Japan)., Proceedings of the 5th Int. Beam Instrumentation Conf., IBIC2016, Barcelona, Spain

In this work we describe a novel beam diagnostic method based on coherence characterization of broad-spectrum bending magnet radiation through the Heterodyne Near Field Scattering (HNFS) technique. HNFS is a self-referencing technique based on the interference between the transmitted beam and the spherical waves scattered by each particle of a colloidal suspension. The resulting single-particle interferogram shows circular fringes modulated by the spatio-temporal Complex Coherence Factor (CCF) of the radiation. Superposition of a number of these patterns results in a stochastic speckle field, from which spatial and temporal coherence information of the source can be retrieved in near field conditions. Here we describe the basics of this technique, the experimental setup mounted along the hard X-ray pinhole at the ALBA synchrotron light source, and the possibility of transverse electron beam size retrieval from the spatial coherence function of the emitted dipole radiation. We also show preliminary results concerning power spectral density of visible synchrotron radiation as obtained from temporal coherence., Proceedings of the 5th Int. Beam Instrumentation Conf., IBIC2016, Barcelona, Spain

During the LHC long shut down in 2014, the transverse beam size diagnostics based on synchrotron radiation was upgraded in order to cope with the increase of the LHC beam energy to 6.5 TeV. The wavelength used for imaging was shifted to near ultra-violet to reduce the contribution of diffraction to the system resolution, while in parallel, a new diagnostic system based on double slit interferometry was installed to measure the beam size by studying the spatial coherence of the emitted synchrotron radiation. This method has never been implemented before in a proton machine. A Hartmann mask was also installed to identify possible wavefront distortions that could affect the system accuracy. This paper will focus on the comparison of visible and the near ultra-violet imaging and on the first experience with interferometry., Proceedings of the 7th Int. Particle Accelerator Conf., IPAC2016, Busan, Korea

In order to study the feasibility of Optical Transition (OTR) and Diffraction (ODR) Radiation based profile measurement for the future electron-positron linear colliders (ILC, CLIC) a new dedicated instrument is under development at CERN to be installed in KEK-ATF2 beam line in fall 2015. To optimize sensitivity to micron and sub-micron beam sizes, we plan to observe ODR/OTR in the visible-UV wavelength range, down to approximately 150 nm. ODR light will be produced by narrow (25-500 μm) slits with non-uniform reflectivity. To improve our knowledge on the complex pattern produced by ODR, a preparatory experiment is being conducted on the CTF3 CALIFES beam line (CERN). This device produces interferences between two OTR screens in the visible optical range with the possibility to control the distance between them, i.e. to probe the shadowing region. The new results of this OTR interference measurement will be presented, together with the latest results from the ODR run in CesrTA (Wilson lab-Cornell)., Proceedings of the 4th International Beam Instrumentation Conference, IBIC2015, Melbourne, Australia

Optical Transition Radiation (OTR) is emitted when a charged particle crosses the interface between two media with different dielectric properties. It has become a wide-spread method for beam profile measurements. However, there are no tools to simulate the propagation of the OTR electric field through an optical system. Simulations using ZEMAX have been performed in order to quantify optical errors, such as aberrations, diffraction, depth of field and misalignment. This paper focuses on simulations of vertically polarized OTR photons with the aim of understanding what limits the resolution of realistic beam imaging systems., Proceedings of the 5th Int. Particle Accelerator Conf., IPAC2014, Dresden, Germany

At the Large Hadron Collider (LHC) at CERN, synchrotron radiation (SR) is used to continuously monitor the transverse properties of the beams. Unfortunately the machine and beam parameters are such that the useful radiation emitted inside a separation dipole, chosen as source, is diffraction limited affecting heavily the accuracy of the measurement. In order to deconvolve the diffraction effects from the acquired beam images and in order to design an alternative monitor based on a double slit interferometer an extensive study of the synchrotron light source and of the optical propagation has been made. This study is based on simulations combining together several existing tools: SRW for the source, ZEMAX for the transport and MATLAB for the "glue" and analysis of the results. The resulting tool is very powerful and can be easily adapted to other synchrotron radiation problems. In this paper the simulation package and the way it is used will be described as well as the results obtained for the LHC and SPS cases., Proceedings of the 5th Int. Particle Accelerator Conf., IPAC2014, Dresden, Germany