nuclear structure physics at the darmstadt superconducting electron linear accelerator s-dalinac

Kerstin Sonnabend, IKP, TU Darmstadt S-DALINAC: Nuclear Structure Physics

Nuclear Structure Physics at the Darmstadt superconducting electron linear accelerator

S-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


Accelerator hall of the S-DALINAC

– electron energies from 2 to 130 MeV available– cw and pulsed beam operation possible– source for polarized electron beams under construction

HIPS


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 (,‘) experiments

– up to four HPGe detectors partly passively shielded partly segmented


HIPS – High-intensity photon setup

11B

11B

1-

1-


Experimental hall of the S-DALINAC

NEPTUN – High-resolution tagger

taggersystem



Energy range: 6 MeV ≤ E ≤ 20 MeV

Energy resolution:E = 25 keV @ 10 MeV

Energy window: ≈ 3 MeV

Photon intensity: ≈ 104 keV-1s-1

1 m

Photon energy: E = Ei - Ee

focal plane

radiator

magnet

coincidence

experiment



– untagged photon spectrum

– tagged photon spectrum: E = 10 MeV

– simulation of detector response



LINTOTT – High-resolution spectrometer

LINTOTT



scatteringchamber

electrons

energy range:18 MeV ≤ Ee ≤ 120 MeV

scatteredelectrons

deflection angle:169.6º ± 0.1º

energy resolution:E/E ≈ 1 10-4

data rate: up to 100 kHz

detectorsystem

detector system:96 silicon strip detectors



94Mo(e,e’)

excitation energy / MeV0 1 2 3 4

coun

ts /

C

0.0

0.1

0.2

O.Burda et al., PRL 99 (2007) 092503

– very good energy resolution (see ground-state)

– ideal method to study one-phonon modes

– far-off yrast spectroscopy possible (up to observed)

€

214+

symmetric octupole phonon

€

31−

symmetric quadrupole phonon

€

21+

mixed-symmetry state

€

23+



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



QCLAM – Large acceptance spectrometer

QCLAM


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 -cluster states in light N = Z nuclei

– (e,e‘) coincidence measurements using Ge detectors



QCLAM

LINTOTT

NEPTUN

HIPS


Photon scattering - Nuclear Resonance Fluorescence

energy

inte

nsi

ty

electrons

electrons

radiatortarget

target

energy

inte

nsi

ty

bremsstrahlung

HPGe

HPGe

U. Kneissl, N. Pietralla, A. Zilges,J. Phys. G 32 (2006) R217

nuclear structure physics at the darmstadt superconducting electron linear accelerator s-dalinac

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