An automatic target monitoring method based on photographs taken by a CMOS photo-camera has been developed for the MEG II detector. The technique could be adapted for other fixed-target experiments requiring good knowledge of their target position to avoid biases and systematic errors in measuring the trajectories of the outcoming particles. A CMOS-based, high resolution, high radiation tolerant, and high magnetic field resistant photo-camera was mounted inside the MEG II detector at the Paul Scherrer Institute (Switzerland). MEG II is used to search for lepton flavor violation in muon decays. The photogrammetric method's challenges, affecting measurements of low momentum particles' tracks, are the high magnetic field of the spectrometer, high radiation levels, tight space constraints, and the need to limit the material budget in the tracking volume. The camera is focused on the dot pattern drawn on the thin MEG II target, about 1 m away from the detector endcaps where the photo-camera is placed. Target movements and deformations are monitored by comparing images of the dots taken at various times during the measurement. The images are acquired with a Raspberry board and analyzed using custom software. Global alignment to the spectrometer is guaranteed by corner cubes placed on the target support. As a result, the target monitoring fulfills the needs of the experiment.

Cavoto G., Chiarello G., Hildebrandt M., Hofer A., Ieki K., Meucci M., et al. (2021). A photogrammetric method for target monitoring inside the MEG II detector. REVIEW OF SCIENTIFIC INSTRUMENTS, 92(4) [10.1063/5.0034842].

A photogrammetric method for target monitoring inside the MEG II detector

Chiarello G.;
2021-04-01

Abstract

An automatic target monitoring method based on photographs taken by a CMOS photo-camera has been developed for the MEG II detector. The technique could be adapted for other fixed-target experiments requiring good knowledge of their target position to avoid biases and systematic errors in measuring the trajectories of the outcoming particles. A CMOS-based, high resolution, high radiation tolerant, and high magnetic field resistant photo-camera was mounted inside the MEG II detector at the Paul Scherrer Institute (Switzerland). MEG II is used to search for lepton flavor violation in muon decays. The photogrammetric method's challenges, affecting measurements of low momentum particles' tracks, are the high magnetic field of the spectrometer, high radiation levels, tight space constraints, and the need to limit the material budget in the tracking volume. The camera is focused on the dot pattern drawn on the thin MEG II target, about 1 m away from the detector endcaps where the photo-camera is placed. Target movements and deformations are monitored by comparing images of the dots taken at various times during the measurement. The images are acquired with a Raspberry board and analyzed using custom software. Global alignment to the spectrometer is guaranteed by corner cubes placed on the target support. As a result, the target monitoring fulfills the needs of the experiment.
1-apr-2021
Settore ING-INF/01 - Elettronica
https://arxiv.org/pdf/2010.11576.pdf
Cavoto G., Chiarello G., Hildebrandt M., Hofer A., Ieki K., Meucci M., et al. (2021). A photogrammetric method for target monitoring inside the MEG II detector. REVIEW OF SCIENTIFIC INSTRUMENTS, 92(4) [10.1063/5.0034842].
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/10447/618915
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