1. 23.10.2008 | Institut für Kernphysik | Project C2 | Anna Maria Heilmann | 1 Construction of a Neutron Ball for Exclusive Electron Scattering Experiments at the S-DALINAC* A.M. Heilmann, M. Chernykh, P. von Neumann-Cosel, A. Richter SFB 634  Motivation  Experimental setup  Experiments  Results  Summary and outlook *Supported by the DFG within SFB 634

2. 23.10.2008 | Institut für Kernphysik | Project C2 | Anna Maria Heilmann | 2 Motivation Isoscalar Giant Dipole Resonance Measurements  exclusive electron coincidence measurements (e,e'n)  almost background-free spectra  supression of the radiative tail  veto detector with a large solid angle S.Strauch, Dissertation, TU Darmstadt (1998)

3. 23.10.2008 | Institut für Kernphysik | Project C2 | Anna Maria Heilmann | 3 Requirements for the Neutron Ball  fast detector response  high neutron efficiency  n/  -discrimination  compact geometry  secondary: energy resolution

4. 23.10.2008 | Institut für Kernphysik | Project C2 | Anna Maria Heilmann | 4 Construction of the Neutron Ball  13 liquid scintillators of the type Bircon BC501A for neutron detection  solid angle of about 1.3 π (for 20 cm)

5. 23.10.2008 | Institut für Kernphysik | Project C2 | Anna Maria Heilmann | 5 Test of the Neutron Ball n/  -Discrimination  AmBe neutron source  zero crossing method

6. 23.10.2008 | Institut für Kernphysik | Project C2 | Anna Maria Heilmann | 6 Test of the Neutron Ball Pulse-Height Calibration measurement: (1) background (2) monoenergetic  sources analysis: (1) dead-time correction (2) background subtraction (3) unfolding starting from high energies

7. 23.10.2008 | Institut für Kernphysik | Project C2 | Anna Maria Heilmann | 7 Test of the Neutron Ball Unfolding of Measured Spectra procedure:  pulse-height simulation NRESP  folding with detector resolution  fit to measured spectra results:  energy dependent detector resolution  position of the compton edge  pulse-height calibration

8. 23.10.2008 | Institut für Kernphysik | Project C2 | Anna Maria Heilmann | 8 Summary design and construction finished tests performed n/  -discrimination pulse-height calibration

9. 23.10.2008 | Institut für Kernphysik | Project C2 | Anna Maria Heilmann | 9 Fission Chamber Preparation for Efficiency Determination with 252 Cf

10. 23.10.2008 | Institut für Kernphysik | Project C2 | Anna Maria Heilmann | 10 Outlook  efficiency determination with 252 Cf (1) ToF method (2) single detectors (3) whole setup (4) simulations  first measurements with heavy nuclei SFB 634