Electron-Transport Task Force report on studying the feasibility of electron stopping experiments C. K. Li for the Task Force Annual Meeting of FSC Laboratory for Laser Energetics January, 2006 This model 1 MeV e MIT

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. Can we do a cold-matter stopping experiment that tests the validity of the new CELSA model?

The new model, with blooming and straggling, predicts different energy deposition than the traditional uniform model  E (keV/ μ m 3 ) r b = 1 μm r b = 10 μm r b = 20 μm r b = 5 μm Uniform model This model  Density (g/cm 3 ) Distance (  m) MeV e

Qualitative similarities exist between new model and cold matter stopping, as reflected in the strong Z dependence DT (Z=1)Be (Z=4)Cu (Z=29) ρR g/cm MeV electrons g/cm 2 ρ ΣBΣB ΣRΣR

Quantitative differences exist between the new model and cold matter stopping

Electron penetration in plasmas is lower than in solids by ~30% DT NIF Direct Drive 350 μm 1.7 mm 350 μm DT ice

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 Excitation/Ionization Free electron Bremsstrahlung Pair production Scatterings Quantum effects Strong coupled Screening effects --- Thomas-Fermi Density effect Stopping in plasma Free electron Bremsstrahlung Pair production Plasma oscillation Scatterings 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

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. Can we do a cold-matter stopping experiment that tests the validity of the new CELSA model?

ITS codes used and validated Scaled=mean I/I 0 Distance R R0R0