The Theory of Charged Particle Energy Loss and Multiple Scattering 理论的带电粒子的能量损失和多重散射.ppt

20 Jan 2004 Oxford Seminar The Theory of Charged Particle Energy Loss and Multiple Scattering in Materials and its Application to Muons in Liquid Molecular Hydrogen ? W W M Allison, Oxford Presented at Oxford 20th January 2004 Overview Plan of talk 1. Theory of the double differential cross section Kinematics Scattering by the atom as a whole and its constituent electrons Nuclear constituent coulomb scattering 2. Data input for atomic and molecular hydrogen 3. Energy Loss and Multiple Scattering in thin H2 absorbers (ELMSA) Study of the contribution of different mechanisms 4. Energy loss and multiple scattering distribut-ions for general absorbers of H2 (ELMSB) ELMS values of RMS 1-D projected PT (MeV/c) ELMS values of RMS98 projected Pt (MeV/c) and ratio to PDG with X0 = 61.28 g cm-2 (corrected for energy loss) 105 incident muons Momentum 200MeV/c Thickness 10cm Linear plot of projected transverse momentum transfer, MeV/c 105 incident muons Momentum 200MeV/c Thickness 10cm Log plot of projected transverse momentum transfer, MeV/c 105 incident muons Momentum 200MeV/c Thickness 10cm Linear plot of energy transfer, MeV 5. Estimation of systematic uncertainties and errors 6. Correlations between the energy loss and scattering distributions Projected Pt dist. for tracks selected by energy loss decile Specific dedx dist. for tracks selected by absolute Pt Comparing first and last decile ...specific dedx and Pt correlations 1mm H2, 200MeV/c The same for higher momentum and thicker...1m H2, 20GeV/c 7. Conclusions Thomas Fermi is crazy for H. Saxon Woods certainly is. They are there for illustration. We will see whether our results are sensitive to even these batty approximations explain the multipole problem PDG lower limit of range is 1 cm of liquid Hydrogen stationary? v=c/137 in H cos term matters a little. The sin term is negligible below Q~M. the factor is ~10**-5 even at 20GeV/c. The CM momentum is quite small! Better get these things right but the