Kerstin Sonnabend, IKP, TU Darmstadt S-DALINAC - Nuclear Astrophysics Nuclear Astrophysics at the...

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

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