High-precision beam profile measurement with a microchannel-plate detector in the high magnetic field of the WISArD experiment

TL;DR

This paper describes the development of a microchannel plate detector capable of high-precision beam profile measurements in strong magnetic fields, tailored for the WISArD experiment at CERN, achieving sub-millimeter accuracy.

Contribution

It introduces a novel image reconstruction method for a resistive anode MCP detector and demonstrates its effectiveness in high magnetic field environments.

Findings

Achieves sub-millimeter beam profile accuracy.

Maintains performance in 4 T magnetic field.

Meets the precision needs for beta-neutrino correlation measurement.

Abstract

We present the development and characterization of a compact low-energy ion beam diagnostic for the WISArD (Weak Interaction Studies with $\mathrm{^{32}Ar}$ Decay) experiment at ISOLDE/CERN. The microchannel plate (MCP) detector, which is configured in a Z-stack and has a resistive position sensitive anode, was tested with both stable and radioactive beams. This work focuses on the image reconstruction method, which corrects the pincushion distortion inherent to the square-shaped resistive anode, and investigates the influence of the magnetic field on the detector performance. Our results demonstrate that the detector achieves beam profile measurements with sub-millimeter accuracy, while coping with the spatial and high-magnetic field (4 T) constraints of the experiment. These capabilities meet the precision requirements of the WISArD experiment for extracting the modified beta-neutrino angular correlation coefficient, \~a$_{\beta\nu}$, with an uncertainty of 0.1%.