Large dynamic range beam profile measurements

Large dynamic range (peak/noise>10⁵) beam profile measurements are routinely performed in the Hall-B beamline at Jefferson Lab. These measurements are made with a 1 to 10 nA electron beam current with energies between 1 to 6 GeV. The electron beam scatters off of a thin (25 μm) W or Fe wire and the scattered particle/shower is detected via scintillation or Cerenkov light several meters downstream of the wire. This light is converted to an electrical pulse via photomultiplier tubes (PMT). The PMT readout and wire motion are controlled and synchronized by VME electronics. This report describes results on increasing the dynamic range by using multiple wires of varying diameters. Profile measurements with this large dynamic range can be of use for machines with very large beam currents (e.g. energy recovering linacs) where any fractional beam loss represents a significant amount of beam power.