Nuclear Astrophysics at the Darmstadt superconducting electron linear accelerator S-DALINAC

Kerstin Sonnabend, IKP, TU Darmstadt S-DALINAC - Nuclear Astrophysics

Nuclear Astrophysics at the Darmstadt superconducting electron linear accelerator

S-DALINAC

Kerstin Sonnabend

ESF Workshop onThe future of stable beams in Nuclear Astrophysics

Athens, Greece

December 14th to 15th, 2007

supported by the DFG under grant No. SFB 634


Contents

S-DALINAC at TU Darmstadt

Photoactivation experiments

– HIPS – High-intensity photon setup

– LCS – Laboratory for counting & spectroscopy

– NEPTUN – High-resolution photon tagger

Electron-scattering experiments

– QCLAM – Large-acceptance spectrometer


S-DALINAC at TU Darmstadt

injector: two 20-cell Nb cavities, up to 11 MeV

main linac: eight 20-cell Nb cavities, up to 40 MeV per circle

first recirculation second recirculation beam extraction

– 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

electrons

Emax

0 ≤ E ≤ Emax

0 ≤ E ≤ Emax

n

Au/Re - target

n

11B - target

N ≈ 105 / (keV s cm2)

≈ 300 · N

collimator

radiator

Activation with continuous-energy bremsstrahlung

K. Sonnabend et al., Astroph. J. 583 (2003) 506K. Vogt et al., Nucl. Phys. A707 (2002) 241


LCS – Laboratory for counting and spectroscopy

– three low-energy photon spectrometers (LEPS)

– four 30% and 40% HPGe detectors

– setups with passive Cu and/or Pb shielding

Pb

Pb

Cu

Cu

LEPS LEPS

Pb Pb

Pb

HPGe

– complementation with x-ray detectors and electron counters

Determination of activation yield with -spectroscopy


LCS – Laboratory for counting and spectroscopy

Sample decay spectra: LEPS versus HPGe



Activation yield Y measured offline

– Use of naturally composed targets (e.g. 196Hg, 198Hg, 199mHg, 200Hg)

– Activate targets simultaneously (e.g. Zr, Re, Ir, and Au)

– Measure weak branchings (e.g. 185W: T1/2 = 75 d, E=125 keV, I≈10-4)

method perfectly suited for systematic studies

Restrictions of activation method

– Appropriate lifetime of product nucleus

– Appropriate transitions during decay of product nucleus

Accelerator Mass Spectrometry (AMS)

– No direct cross section measurements

Use quasi-monoenergetic photon beams, e.g. AIST, Japan

Use tagged photons, e.g. NEPTUN @ S-DALINAC



NEPTUN – High-resolution photon tagger

taggersystem

NEPTUN

5 m



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

electrons

photons



Recent data from test experiment

PPSEDE



Recent data from test experiment

DE SE PP

FWHM ≈ 50 keV

≈ 250 keV



High-resolution cross section measurements

detectorarray

NEPTUN

5 m



– 14 liquid scintillator neutron detectors

– 8 additional 10B enriched liquid scintillator detectors

– high-resolution cross section measurements

– determination of angular momentum of neutrons

– (,p) and (,) in preparation

Determine (,n) cross sections with 100 keV ≤ En ≤ 10 MeV



(e,e‘x) experiments of astrophysical interest

QCLAM

5 m


QCLAM – Large-acceptance spectrometer

– scattering chamber

– quadrupole magnet

– clamshell dipole magnet (deflection angle: 120°)

– three multiwire drift chambers

– plastic scintillation and plexiglas Cherenkov counters


– momentum resolution: p/p = 2 10-4

– solid angle acceptance: 35 msr

– max. central momentum: 200 MeV/c

– momentum acceptance: ±10%




– momentum resolution: p/p = 2 10-4

– solid angle acceptance: 6.4 msr

– max. central momentum: 95 MeV/c

– momentum acceptance: -5% to +8%

Electron scattering at 180° deflection angle



Recent results on M1 deuteron break-up

– high energy resolution and high selectivity of M1 states

– precision test of modern theoretical models

– prediction of p(n,)d cross section at Big Bang energies



Role of neutrino-induced reactions

– properties of pre-collapse core– supernova shock revival– explosive nucleosynthesis

– high resolution (e,e‘) data M1 strength distribution GT0 from shell-model calc. -nucleus cross section

Shell-Modeltotal

Orbital

Spin

52CrS-DALINAC

excitation energy / MeV

K. Langanke et al., PRL 93 (2004) 202501

B(M

1) /

N

B(M

1) /

N

Neutrino Energy / MeV

/ 10

-42

cm2

50Ti

52Cr

54Fe


– production mechanism of 9Be and 10,11B not clear

spallation of 12C by neutrinos

– branching ratios of 12C(e,e‘x)

detection and discrimination of p, d, t, 3He and 4He

E-E-telescopes, TOF and/or PSD

– electro-weak theory

extract (,‘) cross sections


Nucleosynthesis of 9Be and 10B


Experimental hall of the S-DALINAC

QCLAM

NEPTUN

HIPS

Setups for experiments on Nuclear Astrophysics


Many thanks to…

Technische Universität Darmstadt:M. Fritzsche, E. Gehrmann, J. Glorius, J. Hasper,

K. Lindenberg, S. Müller, N. Pietralla,A. Sauerwein, D. Savran, L. Schnorrenberger,

and the QCLAM group

Universität zu Köln:M. Büssing, J. Endres, M. Elvers, and A. Zilges

Roberto Gallino, Torino, Italy

Franz Käppeler, Karlsruhe, Germany

Karlheinz Langanke, Darmstadt, Germany

Alberto Mengoni, Vienna, Austria

Thomas Rauscher, Basel, Switzerland

Nuclear Astrophysics at the Darmstadt superconducting electron linear accelerator S-DALINAC

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