A Time pickup system for monitoring cyclotron beam bursts

Okumura, Susumu; Fukuda, Mitsuhiro; Ishibori, Ikuo; Arakawa, Kazuo

We have developed a time pickup system for monitoring the beam bursts from a cyclotron. The time pickup can measure the phase and the width of the beam bursts by detecting secondary electrons emitted from a foil or a wire target inserted into the beam with time resolutions around 200 ps FWHM (full width at half maximum) in spite of its simple structure. Using the foil and the wire targets appropriately, monitoring the bursts of variety of beams can be achieved. In addition, by adjusting the position of the target, enough detection rate of the beam burst is obtained with minimized interference with the beam. The present investigation shows that it is needed to adjust the collection voltage of the time pickup according to the purposes: the optimum collection voltages for high resolution measurement are in the range from -0.5 to -1.0 kV and those for high efficiency measurement are not less than -4.0 kV.