Nuclear Structure Physics at the Darmstadt superconducting electron linear accelerator S-DALINAC

1. Nuclear Structure Physics at the Darmstadt superconducting electron linear acceleratorS-DALINAC N. Pietralla and K. Sonnabendfor the SFB 634 Workshop on European Small-Scale Accelerator Facilities Aghios Nikolaos, Crete, Greece September 7th to 8th, 2007 supported by the DFG under grant No. SFB 634

2. Accelerator hall of the S-DALINAC HIPS – electron energies from 2 to 130 MeV available – cw and pulsed beam operation possible – source for polarized electron beams under construction

3. HIPS – High-intensity photon setup – continuous-energy bremsstrahlung – 2 MeV ≤ Emax ≤ 11 MeV – photon intensities: 106 keV-1s-1cm-2 – two target positions for simultanuous (g,g‘) experiments – up to four HPGe detectors partly passively shielded partly segmented

4. HIPS – High-intensity photon setup 11B 1- 1- 11B

5. Experimental hall of the S-DALINAC taggersystem NEPTUN – High-resolution tagger

6. NEPTUN – High-resolution tagger magnet 1 m coincidence focal plane radiator experiment Energy range: 6 MeV ≤ Eg ≤ 20 MeV Energy resolution: DE = 25 keV @ 10 MeV Energy window: ≈ 3 MeV Photon intensity: ≈ 104 keV-1s-1 Photon energy: Eg = Ei - Ee

7. NEPTUN – High-resolution tagger – untagged photon spectrum – tagged photon spectrum:Eg = 10 MeV – simulation of detector response

8. Experimental hall of the S-DALINAC LINTOTT LINTOTT – High-resolution spectrometer

9. LINTOTT – High-resolution spectrometer energy range:18 MeV ≤ Ee ≤ 120 MeV detectorsystem deflection angle:169.6º ± 0.1º scatteredelectrons detector system:96 silicon strip detectors electrons scatteringchamber energy resolution:DE/E ≈ 1  10-4 data rate: up to 100 kHz

10. LINTOTT – High-resolution spectrometer 0.2 94Mo(e,e’) counts / mC 0.1 0.0 0 1 2 3 4 excitation energy / MeV – far-off yrast spectroscopy possible (up to observed) •  symmetric quadrupole phonon •  symmetric octupole phonon •  mixed-symmetry state – very good energy resolution (see ground-state) – ideal method to study one-phonon modes O.Burda et al., PRL 99 (2007) 092503

11. LINTOTT – High-resolution spectrometer Planned experimental program • Determination of excitation strengths and form factorsof low-spin excitations • – mixed-symmetry states in mass regions A = 90 and 130 • – intrinsic structures in shape-phase transitional nuclei • – investigation of new electric dipole modes (besides IVGDR) • form factors of PDR states in N = 82 isotones and 208Pb • find evidence for purely transverse E1 mode below GDR

12. Experimental hall of the S-DALINAC QCLAM QCLAM – Large acceptance spectrometer

13. QCLAM – Large-acceptance spectrometer Planned experimental program • – (e,e‘x) coincidence experiments for the investigation of new electric dipole modes (besides IVGDR) • form factors of PDR states in N = 82 isotones and 208Pb • find evidence for purely transverse E1 mode below GDR • – excitation and decay of ISGDR in 58Ni, 90Zr, 140Ce, and 208Pb • – experiments on a-cluster states in light N = Z nuclei • – (e,e‘g) coincidence measurements using Ge detectors

14. Experimental hall of the S-DALINAC NEPTUN HIPS QCLAM LINTOTT

15. Photon scattering - Nuclear Resonance Fluorescence HPGe target electrons radiatortarget electrons bremsstrahlung intensity intensity HPGe energy energy U. Kneissl, N. Pietralla, A. Zilges,J. Phys. G 32 (2006) R217