Transverse profile tomography of a high current proton beam with a multi-wire scanner

摘要

This paper describes the measurement of the transverse, two-dimensional profile of the high current proton beam in the linac at the Tsinghua University, by tomography mapping using a rotatable multi-wire scanner. The experiment is conducted at a beam energy of 3 MeV, a peak current of up to 32 mA, a repetition frequency of 20 Hz, and a beam pulse width of $50ext{ }ext{ }ensuremath{mu}mathrm{s}$. The transverse density distribution is reconstructed utilizing the algebraic reconstruction technique (ART), by using the beam profiles measured at different rotation angles. The beam profile, measured at a fixed rotation angle, is obtained by 19 parallel carbon wires mounted on one board of the wire scanner monitor (WSM) moving along a straight line with a step increment of 0.1 mm. The results gathered from the computer tomography (CT) method could be verified by an independent profile measurement downstream of a multiple-slit aperture. This paper presents first measurement results of the high current proton beam during normal operation of the linac at the Tsinghua University. A dynamic range of $1{0}^{2}$ for the two-dimensional distribution was achieved.