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

S. Lecanuet, X. Fléchard, P. Alfaurt, P. Ascher, D. Atanasov, B. Blank, L. Daudin, H. DePreaumont, M. Gerbaux, J. Giovinazzo, S. Grévy, G. Guignard, J. Ha, C. Knapen, S. Lechner, A. Lépine, J. Lory, J. Perronnel, M. Pomorski, M. Roche, C. Roumegou, N. Severijns, Y. Son, S. Vanlangendonck, M. Versteegen, D. Zakoucky

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, ã$_{βν}$, with an uncertainty of 0.1%.

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

Abstract

We present the development and characterization of a compact low-energy ion beam diagnostic for the WISArD (Weak Interaction Studies with 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, ã, with an uncertainty of 0.1%.
Paper Structure (13 sections, 8 equations, 14 figures, 1 table)

This paper contains 13 sections, 8 equations, 14 figures, 1 table.

Table of Contents

  1. Introduction
  2. MCP detector design
  3. Choice of the position sensitive anode and MCP assembly
  4. Mechanical design
  5. Detector read-out
  6. Characterization with stable beam
  7. Event selection
  8. Image reconstruction and position calibration
  9. Detector resolution and performances
  10. Effect of the magnetic field
  11. $\mathrm{^{32}Ar}$ beam profile measurement
  12. Beam profile extraction
  13. Summary and conclusions

Figures (14)

  • Figure 1: CAD view of the WISArD detection setup with the radioactive beam in fluorescent green implanted on the catcher. The MCP has been integrated at the bottom of the tower (here in out position). See Ref. Dinko_2023 for further details.
  • Figure 2: Bottom view of the WISArD experimental tower with the MCP position out (a) and in (b). The catcher foil stopping the beam during data taking is held by the white PEEK ring at the center of the tower. The calibration mask geometry is the 2024 version.
  • Figure 3: Exploded view of the MCP detector assembly. See text for details.
  • Figure 4: Picture of the front (a) and back (b) side of the detector with the 2024 mask geoemtry.
  • Figure 5: MCP detector electronic read-out, see text for details.
  • ...and 9 more figures