title: Note: Effect of photodiode aluminum cathode frame on spectral sensitivity in the soft x-ray energy band.
abstract: Silicon photodiodes used for soft x-ray detection typically have a thin metal electrode partially covering the active area of the photodiode, which subtly alters the spectral sensitivity of the photodiode. As a specific example, AXUV4BST photodiodes from International Radiation Detectors have a 1.0 μm thick aluminum frame covering 19% of the active area of the photodiode, which attenuates the measured x-ray signal below ~6 keV. This effect has a small systematic impact on the electron temperature calculated from measurements of soft x-ray bremsstrahlung emission from a high-temperature plasma. Although the systematic error introduced by the aluminum frame is only a few percent in typical experimental conditions on the Madison Symmetric Torus, it may be more significant for other instruments that use similar detectors.
authors.affiliation: Department of Physics, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA.
authors.forename: M B
authors.initials: MB
authors.lastname: McGarry
authors.affiliation: Consorzio RFX, Associazione Euratom-ENEA per la Fusione, Padova, Italy.
authors.forename: P
authors.initials: P
authors.lastname: Franz
authors.affiliation: Department of Physics, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA.
authors.forename: D J
authors.initials: DJ
authors.lastname: Den Hartog
authors.affiliation: Department of Physics, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA.
authors.forename: J A
authors.initials: JA
authors.lastname: Goetz
authors.affiliation: Department of Physics, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA.
authors.forename: J
authors.initials: J
authors.lastname: Johnson