Physik mit Neutronen allgemein 2.1 Neutronen-Streuung 2.3 Angewandte Neutronenphysik

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Physik mit Neutronen allgemein 2.1
Neutronen-Streuung2.3 Angewandte Neutronenphysik
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2.1 Neutronen-Streuung (starke WW magn. WW)
1. elastische Streuung
Bragg Impulsübertrag reziproker
Gittervektor ?kn G , ?En 0
Pulver Diffraktometer, Debye Scherrer
? vom Reaktor
Monochromator ?
Probe ?
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ToF-Diffraktometer an gepulster Spallationsquelle
The General Materials Diffractometer at the ISIS
pulsed neutron source to study the structure of
disordered materials and crystalline powders.
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NEUTRONEN SEHEN SEHR GUT LEICHTE ATOME
im Ggs. zu Röntgen
Physisorption von Heptan auf Kristall Oberflächen
Debye Scherrer Aufnahme Thermodiffractometrie
einer Monolage, 2.4 Å
"The two-dimensional structure of the heptane
monolayer could be solved."
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NEUTRONEN SEHEN EINZELNE ISOTOPE
D2O Anfärbung "Kontrast-Variation"
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NEUTRONEN SEHEN MAGNETISMUS
T lt TC Antiferromagnet T gt TC Paramagnet
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Spin density map
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Spintronik
Giant magneto-resistance effect
NEUTRONEN-REFLEKTOMETRIE n-Streu-Intensität als
Fkt. von Einfalls- und Ausfallswinkel Experiment
Theorie
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NEUTRONEN SEHEN MOLEKULARE BEWEGUNGEN
2. inelastische Streuung
z.B. Phononen
Transverse optical mode for diatomic chain
Transverse acoustical mode for diatomic chain
q, qh/?
En kT meV Anregungsenergie FK ? Å
Gitterkonstante FK ?kn G q , ?En h?
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Neutronen-Spektrometer schematisch
En'
?En h?
?kn Gq
En
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Neutronen-Spektrometer real
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dynamics of carbon nanotubes
phonon dispersion relations and phonon density of
states for single walled carbon nanotubes, 101 nm
length.
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NEUTRONEN SEHEN SEHR LANGSAME BEWEGUNGEN
S(Q,t) in highly entangled polyethylene melts
Illustration of de Gennes reptation concept,
restricting motion within a tube.
S(Q,t) vs. t for various Q. Red lines fit of
the reptation model. Blue lines fit using the
model of des Cloizeaux. The tube diameter found
is 46.0 0.1 Å.
n-Spinecho Spektrometer n-Rückstreu Spetrometer
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Rotations-Tunneln von Methan CH4

• Methane is the simplest organic molecule.
• Tunnelling spectrum of 1.5 CH4 in CD4

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r-process
2.2 Kernphysik mit Neutronen
S. Paul primord. Elemente
How are the heavy elements formed?
Breeding in red giants (slow 's-process') GAMS
?-Spektrometer Super-Nova explosions (rapid
'r-process') LOHENGRIN Spaltprod. Spektr.
Super-Novae refuse to explode on the computer.
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Parity non-conservation of bulk matter
PNC transmission
polarized neutrons
"isotropic" material
unpolarized neutron beam
PNC. Asym.
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PNC spin rotation
?PNC Im(C) 10 4 rad/cm
'neutron-optical activity'
PNC Spin Rot
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PNC fission asymmetry
a 10 4
light fission product
polarized neutron beam
fissible material
heavy fission product
Wu-experiment with 'mesoscopic' objects
PNC Fission
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Neutron Interferometer
Neutronenoptische Experimente
A three blade neutron interferometer, machined
from a single crystal silicon ingot. ? A
monoenergetic neutron beam is split by the first
blade and recombined in the third blade. ? If a
sample is introduced in one of the paths, a phase
difference in the wave function is produced, and
interference between the recombined beams causes
count rate shifts of opposite sign in the two
detectors. ?
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NEUTRONEN SIND DURCHDRINGEND
2.2 Angewandte Neutronenphysik
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