Beam Tail Measurements using Wire Scanners at DESY

Wire scanners are used usually to measure the profile of the core of the beam. Especially at high beam currents the wire has to flip very fast through the beam, otherwise it will burn This is not true for the tails of the beam where the wire can be moved very slowly (or even stay stationary). Two effects are described which can be used to determine the tail distribution of the beam with the help of a slow wire scan. First: Counting of the scattered beam (tail) particles by scintillation counters. The rate versus the wire position will give directly the particle distribution in the tail. Second: The temperature of the wire depends on the amount of beam particle interactions with the wire. A temperature increase leads to an elongation of the wire and a dramatic change of its tension. This can be measured by the change of the natural frequency of the wire. Both methods are very sensitive and have a large dynamic range. The devices will be described and first results will be presented