| Institut für Kernphysik | Project C2 | Inna Pysmenetska | 1 Precision Measurement of the Proton Charge Radius with Elastic Electron Scattering* SFB 634 P. von Neumann-Cosel, I. Pysmenetska, S. Rathi, A. Richter, G. Schrieder and A. Shevchenko *Supported by the DFG within SFB 634  Motivation  Experimental technique  Measured spectra  Results  Summary and Outlook

| Institut für Kernphysik | Project C2 | Inna Pysmenetska | 2 Motivation  proton radius fundamental quantity in physics important for nuclear theory  recent Lamb shift measurements as a test of QED theory limited by higher order corrections, which depend on R p

| Institut für Kernphysik | Project C2 | Inna Pysmenetska | 3 Measuring Method

| Institut für Kernphysik | Project C2 | Inna Pysmenetska | 4 Previous Results

| Institut für Kernphysik | Project C2 | Inna Pysmenetska | 5 New Idea: Detect Protons and not Electrons! q = ( fm -1 ) in a single run  avoid difficult normalization  complete angular distribution  measured simultaneously  precise definition of solid angle  Rosenbluth separation  proton detection efficiency is ~1

| Institut für Kernphysik | Project C2 | Inna Pysmenetska | 6 Problems  background  definition of absolute cross section  precise definition of beam, target and detector position  target evaporation

| Institut für Kernphysik | Project C2 | Inna Pysmenetska | 7 Experimental Setup  Beam Slits  Detector Collimators  Symmertic Detector  Spectrometer

| Institut für Kernphysik | Project C2 | Inna Pysmenetska | 8 Experimental Setup

| Institut für Kernphysik | Project C2 | Inna Pysmenetska | 9 Measured Spectra

| Institut für Kernphysik | Project C2 | Inna Pysmenetska | 10 Background at Different Angles  PSD Method ª TOF Method

| Institut für Kernphysik | Project C2 | Inna Pysmenetska | 11 Measured Spectra

| Institut für Kernphysik | Project C2 | Inna Pysmenetska | 12 Projected Spectra

| Institut für Kernphysik | Project C2 | Inna Pysmenetska | 13 Pulse Shape Discrimination Method  Pulse shape discrimination finite drift time of charge carriers  Reverse detector mounting current pulse dominated by holes A. Fazzi et al., IEEE Trans. Nucl. Sci. 51 (2004) 1049.

| Institut für Kernphysik | Project C2 | Inna Pysmenetska | 14 Test of PSD Method

| Institut für Kernphysik | Project C2 | Inna Pysmenetska | 15 Measured Energy Spectra

| Institut für Kernphysik | Project C2 | Inna Pysmenetska | 16 Measured Energy Spectra

| Institut für Kernphysik | Project C2 | Inna Pysmenetska | 17 Measured Energy Spectra

| Institut für Kernphysik | Project C2 | Inna Pysmenetska | 18 Measured Energy Spectra

| Institut für Kernphysik | Project C2 | Inna Pysmenetska | 19 Experiment Requirements

| Institut für Kernphysik | Project C2 | Inna Pysmenetska | 20 Summary & Outlook SFB 634  Status complete setup setup adjustment  Beam requirements 80 MeV pulsed beam halo free  Experiment first half 09