title: Source characterization and modeling development for monoenergetic-proton radiography experiments on OMEGA.
abstract: A monoenergetic proton source has been characterized and a modeling tool developed for proton radiography experiments at the OMEGA [T. R. Boehly et al., Opt. Comm. 133, 495 (1997)] laser facility. Multiple diagnostics were fielded to measure global isotropy levels in proton fluence and images of the proton source itself provided information on local uniformity relevant to proton radiography experiments. Global fluence uniformity was assessed by multiple yield diagnostics and deviations were calculated to be ∼16% and ∼26% of the mean for DD and D(3)He fusion protons, respectively. From individual fluence images, it was found that the angular frequencies of ≳50 rad(-1) contributed less than a few percent to local nonuniformity levels. A model was constructed using the Geant4 [S. Agostinelli et al., Nuc. Inst. Meth. A 506, 250 (2003)] framework to simulate proton radiography experiments. The simulation implements realistic source parameters and various target geometries. The model was benchmarked with the radiographs of cold-matter targets to within experimental accuracy. To validate the use of this code, the cold-matter approximation for the scattering of fusion protons in plasma is discussed using a typical laser-foil experiment as an example case. It is shown that an analytic cold-matter approximation is accurate to within ≲10% of the analytic plasma model in the example scenario.
authors: Plasma Science and Fusion Center, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, USA.
authors: M J-E
authors: MJ
authors: Manuel
authors: A B
authors: AB
authors: Zylstra
authors: H G
authors: HG
authors: Rinderknecht
authors: D T
authors: DT
authors: Casey
authors: M J
authors: MJ
authors: Rosenberg
authors: N
authors: N
authors: Sinenian
authors: C K
authors: CK
authors: Li
authors: J A
authors: JA
authors: Frenje
authors: F H
authors: FH
authors: Séguin
authors: R D
authors: RD
authors: Petrasso