Fast data acquisition system of a non-destructive profile monitor for a synchrotron beam by using a microchannel plate with multi-anodes

Abstract

A microchannel plate (MCP) is a good sensor for the head of a non-destructive profile monitor (NDPM) in a synchrotron ring. The gain of the sensor can be controlled from 1 to 104 by adjusting the bias voltage on the MCP. If the gain of the MCP is not sufficient for observing a polarized beam with an intensity which is about one thousandth of the normal beam intensity, two MCPs in series (tandem type) should be used for the sensor. The conventional type of NDPM takes data by moving an MCP with a narrow window from the end of the beam size to the other end during many acceleration periods. Therefore, the measured beam profile is the average of the beam dynamics over many acceleration periods, and data taking requires a long time. The fast NDPM data acquisition system introduced in this article can obtain a beam profile from injection into a synchrotron to extraction only for one acceleration period. The head of the NDPM is a large rectangular MCP having multi-anodes of a strip line. Each anode has an independent electric system for data taking into a computer. In a parallel data acquisition system, such as this monitor system, the calibration of the whole gain of each channel from the MCP to the analog-to-digital converter (ADC) is the most important. In our system, this is done by longitudinally rotating the MCP by 90° (i.e., the direction of the anode strips is set perpendicular to the beam direction).