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Electron-Transport Task Force report on studying the feasibility of electron stopping experiments MIT This model 1 MeV e C. K. Li for the Task Force Annual Meeting of FSC Laboratory for Laser Energetics 26-27 January, 2006 Can we do a cold-matter stopping experiment that tests the validity of the new CELSA model? • The motivation for such a test is, in part, that the new model, with blooming and straggling, predicts different energy deposition than the traditional uniform model • There is no obvious quantitative path to such a verification. The new model, with blooming and straggling, predicts different energy deposition than the traditional uniform model 60.0 Uniform model 40.0 Density (g/cm3) r rb = 1 μm This model 20.0 0.0 3.00 2.00 300 1-MeV e dE 1.00 (keV/μm3) 0.60 rb = 5 μm 0.00 0.40 0 0 5 10 15 Distance (mm) 20 25 rb = 10 μm 0.20 0.00 0.15 0.10 rb = 20 μm 0.05 0.00 0 5 10 15 20 Penetration (μm) 25 Qualitative similarities exist between new model and cold matter stopping, as reflected in the strong Z dependence 1 MeV electrons g/cm2 0.5 DT (Z=1) Be (Z=4) Cu (Z=29) ΣB 0 ΣR ρ<x> 0 0.7 0 g/cm2 ρR g/cm2 g/cm2 0.7 Quantitative differences exist between the new model and cold matter stopping dE/rs (MeV cm 2/g) DT plasma, 10 eV, 0.25 g/cm3 B-S Pseudo-DT 0.25 g/cm3 40 30 20 10 0.01 0.1 1 Electron Energy (MeV) 10 Electron penetration in plasmas is lower than in solids by ~30% DT Plasma, 10 eV, 0.25 g/cm3 DT Plasma, 5 keV, 0.25 g/cm3 Pseudo-Solid DT, 0.2225 g/cm3 0 (g/cm 2) 10 350 μm DT ice -1 10 r<X> -2 10 NIF Direct Drive -3 DT 10 350 μm -4 10 10 100 1000 Energy (keV) 10000 1.7 mm Consideration of a cold matter stopping experiment for testing the CELSA model • Would we be able to convincingly demonstrate that a proof of cold matter stopping, beyond that which already exists in the literature, would unambiguously prove the veracity of the CELSA model? • Given that the literature and work on electron stopping in cold matter is so extensive and exhaustive, is there any experiment that we could do, or lead for the ETTF or the FSC, that would extend our understanding, in a fundamental way, of straggling and blooming processes in cold matter? There are no straightforward quantitative collections between electron stopping in cold matters and in plasmas Stopping in cold matter Stopping in plasma Excitation/Ionization Free electron Bremsstrahlung Pair production Free electron Bremsstrahlung Pair production Plasma oscillation Scatterings Scatterings Quantum effects Strong coupled Screening effects --- Thomas-Fermi Density effect Quantum effects Strong/weak coupled Screening effects --- Debye ....... ....... • While there are many common elements, NON counterpart physics exist • Even for common elements, the level and scale are different Can we do a cold-matter stopping experiment that tests the validity of the new CELSA model? • The motivation for such a test is, in part, that the new model, with blooming and straggling, predicts different energy deposition than the traditional uniform model • There is no obvious quantitative path to such a verification. ITS codes used and validated I/I0 10 Energy (MeV) Schonland/Varder ITS Scaled EXP B-S Geant4 1 R Distance 0.1 10 100 1000 Range in Al (mg/cm 2) Scaled=mean 10000 R0