Modelling the path length of aluminium seen by the detectors in the MIRI instrument on the JWST

A. C.H. Glasse, D. Lee, P. Samara-Ratna, G. H. Rieke

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

The MIRI instrument on the James Webb Space Telescope is equipped with detectors which are susceptible to signal disruption by the charge deposited from impacting cosmic rays. In order to quantify the degree to which the structure of MIRI will shield the detectors, we have used an opto-mechanical ray tracing approach, whereby the solid bodies in a detailed 3D model of the instrument are substituted with an absorptive glassy material. By importing this modified model into a ray tracing program (Tracepro) and then launching many rays from the detector, we have been able to generate a map of aluminium path length as a function of direction. We find that there is a minimum thickness of 2 to 3 mm over a few patches which subtend no more than 1.5 % of the sky for the worst case, imager detector. We discuss the performance of the shielding provided by the MIRI structure, concluding that this minimum thickness of aluminium is sufficient to suppress the impact of low energy protons below the level of the unavoidable flux due to high energy cosmic rays.

Original languageEnglish (US)
Title of host publicationSpace Telescopes and Instrumentation 2020
Subtitle of host publicationOptical, Infrared, and Millimeter Wave
EditorsMakenzie Lystrup, Marshall D. Perrin
PublisherSPIE
ISBN (Electronic)9781510636736
DOIs
StatePublished - 2020
EventSpace Telescopes and Instrumentation 2020: Optical, Infrared, and Millimeter Wave - Virtual, Online, United States
Duration: Dec 14 2020Dec 22 2020

Publication series

NameProceedings of SPIE - The International Society for Optical Engineering
Volume11443
ISSN (Print)0277-786X
ISSN (Electronic)1996-756X

Conference

ConferenceSpace Telescopes and Instrumentation 2020: Optical, Infrared, and Millimeter Wave
Country/TerritoryUnited States
CityVirtual, Online
Period12/14/2012/22/20

Keywords

  • Cosmic ray
  • Infrared astronomy
  • JWST
  • MIRI
  • Optical modelling
  • Solid modelling
  • Space observatory

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Computer Science Applications
  • Applied Mathematics
  • Electrical and Electronic Engineering

Fingerprint

Dive into the research topics of 'Modelling the path length of aluminium seen by the detectors in the MIRI instrument on the JWST'. Together they form a unique fingerprint.

Cite this