{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,13]],"date-time":"2026-10-13T13:46:52Z","timestamp":1791899212734,"version":"4.3.4"},"reference-count":20,"publisher":"AIP Publishing","issue":"10","license":[{"start":{"date-parts":[[2026,10,13]],"date-time":"2026-10-13T00:00:00Z","timestamp":1791849600000},"content-version":"vor","delay-in-days":12,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Eni SpA"},{"name":"MIT UROP Program"},{"name":"MIT FUSars Program"}],"content-domain":{"domain":["pubs.aip.org"],"crossmark-restriction":true},"short-container-title":[],"published-print":{"date-parts":[[2026,10,1]]},"abstract":"<jats:p>In nuclear fusion reactors, deuterium and tritium are fused together. Most reactions produce a 4He ion and a 14\u00a0MeV neutron, while about 2 \u00d7 10\u22125 of them produce a 5He ion and a gamma photon. One of the most important measurements from a fusion reactor is the total fusion power, which can be measured using the 14\u00a0MeV neutrons or the gamma-rays. Using both provides two independent measurements, which is valuable for researchers and regulators. Facilities such as JET use scintillators such as LaBr3 to measure gamma-ray emission, but such detectors could struggle with background on high-power reactors such as SPARC and ITER. We propose that a magnetic electron recoil gamma-ray spectrometer (MERGS) can make gamma-ray measurements in these high-background environments. MERGS will consist of a foil that converts photons to electrons via Compton scattering, a magnetic electron-optic system that focuses and disperses the electron beam, and a detector array that counts the electrons and uses their positions to infer their energy. A conceptual design framework of MERGS is presented, along with three numerically optimized electron-optic geometries for three different resolution requirements. Simulations are presented showing that each presented design can meet its requirements. This shows that MERGS can measure the gamma-ray emission spectrum more effectively than scintillators for a variety of price points, enabling improved measurements of fusion power as well as the study of fast ion physics via other nuclear reactions.<\/jats:p>","DOI":"10.1063\/5.0350449","type":"journal-article","created":{"date-parts":[[2026,10,13]],"date-time":"2026-10-13T12:57:02Z","timestamp":1791896222000},"update-policy":"https:\/\/doi.org\/10.1063\/aip-crossmark-policy-page","source":"Crossref","is-referenced-by-count":0,"title":["Conceptual design of the electron-optics of the magnetic electron recoil gamma-ray spectrometer"],"prefix":"10.1063","volume":"97","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-7076-5891","authenticated-orcid":false,"given":"J. 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