Beam Diagnostics Using a Vibrating Wire Monitor

Abstract

It is customary to use thin wires to scan charged particle beams in accelerator facilities all over the world. Secondary particles after scattering off the wire are measured and the intensity is proportional to how many number of particles have been penetrated through. In this paper, a new technique which is called Vibrating Wire Monitor (VWM) to scan the particle beams by wires is introduced. The principle of the VWM operation is based on the shifted frequency from its own natural oscillation frequency generated by AC drive current through the wire with a permanent magnetic field at the end of the wire. Heating quantity plays a crucial role in this case as the number of particles penetrated through the wire is proportional to a change of the frequency of the wire because of the heating. This shifted frequency can be measured and used to diagnose the beam profile after irradiation to the wire. It has not only an exceptional sensitivity and a huge dynamic range compared to any other beam diagnostic devices but also small and portable measurement system. Old types of beam profile monitors typically have weak sensitivity to measure the beam halo and weak energy beam because of its lack of wide dynamic range. The VWM also can be used in profiling and detecting Lasers, neutrons, electrons and protons regardless of the beam type. However, since the characteristic time of heat transfer limits the speed of the measurement time by VWM, another type of wire scanner method which is called Resonant Target Vibrating Wire Monitor (RT-VWM) to reduce the scanning time has been being developed. Also, due to the rapid development of science and technology including Nano science, biology, space science and accelerator, etc., Many of countries are putting their efforts to build accelerator facilities on the purpose of not only for detecting new phenomenon but also to help understanding and observing microscopic world of biology and Nano science. In this perspective of view, it is very necessary to diagnose the beam once the construction of beam facility is finished and operating. Since VWM can be used to diagnose the beam with unprecedented sensitivity regardless of beam types, it can be adopted to every beam facilities easily all over the world. Old fashioned beam diagnostic devices usually focus on the beam core region due to the lack of sensitivity on the vicinity of beam halo region. However, since it has a wide dynamic range compared to other beam diagnostic devices, it is proper to diagnose the beam quality from beam facilities around the world and to help other fields of science in the future.