Novel Bunch Length Diagnostic

Bunches of charged particle are created by all accelerators due to the nature of the acceleration process. The temporal bunch length is a fundamental accelerator parameter that determines how the accelerator is performing and how it can be optimized, e.g. to make useful radiation. Bunch length is difficult to measure especially as the beam pulses become very short, e.g. microns or less. We have developed a new method to measure the average bunch length over a very wide range of sizes that is simple, easy to implement and less costly than other techniques. In Phase I we propose to validate this method experimentally. We propose to experimentally test and validate our new diagnostic on two electron beam accelerators with much different energies and bunch lengths and compare our results to standard diagnostic techniques. The technique we are developing requires imaging the spatial and angular distributions of coherent radiation generated by the charged particle (e.g. electron) bunch as it passes through a hole or through a foil. Before making our measurements, we will first estimate using computer simulations the ranges of beam parameters (e.g. the energy and the range of bunch lengths) that are expected for a particular accelerator, in order to design our experimental imaging system. We will then image the radiation, analyze the data to produce the bunch length and compare our results to other available diagnostics in order to validate our new method. There are over 30,000 accelerators in the world. All of these machines require a complement of diagnostics to operate and optimize their performance. A successful validation of the technique we are developing could lead to a commercial product that would be useful to a large number of accelerators with energies in the range of 10 to 12,000 million electron volts. These machines are used for a great variety of scientific and practical applications, e.g. drivers for x-ray free electron lasers, nuclear physics research, medical therapies and materials processing to name only a few.