title: Impact of x-ray dose on track formation and data analysis for CR-39-based proton diagnostics.
abstract: The nuclear track detector CR-39 is used extensively for charged particle diagnosis, in particular proton spectroscopy, at inertial confinement fusion facilities. These detectors can absorb x-ray doses from the experiments in the order of 1-100 Gy, the effects of which are not accounted for in the previous detector calibrations. X-ray dose absorbed in the CR-39 has previously been shown to affect the track size of alpha particles in the detector, primarily due to a measured reduction in the material bulk etch rate [Rojas-Herrera et al., Rev. Sci. Instrum. 86, 033501 (2015)]. Similar to the previous findings for alpha particles, protons with energies in the range 0.5-9.1 MeV are shown to produce tracks that are systematically smaller as a function of the absorbed x-ray dose in the CR-39. The reduction of track size due to x-ray dose is found to diminish with time between exposure and etching if the CR-39 is stored at ambient temperature, and complete recovery is observed after two weeks. The impact of this effect on the analysis of data from existing CR-39-based proton diagnostics on OMEGA and the National Ignition Facility is evaluated and best practices are proposed for cases in which the effect of x rays is significant.
authors.affiliation: Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
authors.forename: H G
authors.initials: HG
authors.lastname: Rinderknecht
authors.affiliation: Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
authors.forename: J
authors.initials: J
authors.lastname: Rojas-Herrera
authors.affiliation: Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
authors.forename: A B
authors.initials: AB
authors.lastname: Zylstra
authors.affiliation: Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
authors.forename: J A
authors.initials: JA
authors.lastname: Frenje
authors.affiliation: Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
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authors.initials: M
authors.lastname: Gatu Johnson
authors.affiliation: Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
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authors.initials: H
authors.lastname: Sio
authors.affiliation: Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
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authors.initials: N
authors.lastname: Sinenian
authors.affiliation: Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
authors.forename: M J
authors.initials: MJ
authors.lastname: Rosenberg
authors.affiliation: Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
authors.forename: C K
authors.initials: CK
authors.lastname: Li
authors.affiliation: Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
authors.forename: F H
authors.initials: FH
authors.lastname: Séguin
authors.affiliation: Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
authors.forename: R D
authors.initials: RD
authors.lastname: Petrasso
authors.affiliation: State University of New York at Geneseo, Geneseo, New York 14454, USA.
authors.forename: T
authors.initials: T
authors.lastname: Filkins
authors.affiliation: Rochester Institute of Technology, Rochester, New York 14623, USA.
authors.forename: Jeffrey A
authors.initials: JA
authors.lastname: Steidle
authors.affiliation: State University of New York at Geneseo, Geneseo, New York 14454, USA.
authors.forename: Jessica A
authors.initials: JA
authors.lastname: Steidle
authors.affiliation: State University of New York at Geneseo, Geneseo, New York 14454, USA.
authors.forename: N
authors.initials: N
authors.lastname: Traynor
authors.affiliation: State University of New York at Geneseo, Geneseo, New York 14454, USA.
authors.forename: C
authors.initials: C
authors.lastname: Freeman