Nuclear Resonant Scattering (NRS) and its Applications ...
Transcript of Nuclear Resonant Scattering (NRS) and its Applications ...
Nuclear Resonant Scattering (NRS)and its Applications using pulsed SR
Feb 28, 2005Dr. Zhang Xiaowei
Why Nuclear Scattering usingSynchrotron Radiation?
1) Obtain an ultra-monochromatic x-ray beam:a frontier of energy resolution
2) Develop some new experimental techniques: inelastic, quasi-elastic x-ray scattering
3) Develop new possibility of traditional Mössbauerspectroscopy4) Develop applications of ultra-
monochromatic x-ray beam: x-ray wavelengthstandard
γ-ray vs. synchrotron radiation
ideallyΔE~100µeVEnergytunability
ideallydifficultPulsed radiation
ideallypoor or difficultPolarization
>1051Relativebrilliance
10-3~10-2eV10-8eVEnergybandwidth
SRγ-ray
Overcome a huge S/N
forbiddenallowedlySpecialized
opticaldevice
E1M1, E2Polarizationdependence
Prompt responseTime-delayedresponse
Time gateddetection
Noise (Electricscattering)
Signal (Nuclearscattering)technique
Ultra-monochromatic x-raybeam can only be obtainedfrom a nuclear system insolid, can not be obtainedfrom any electric systems.
Resolution power ofdiffraction lattice is limited byerror of Δd/d.
Nature of nuclei frequencyresonance in x-ray range(Mössbauer resonance) is akey technique of Ultra-monochromatic x-ray beam.
To separate nuclear resonantsignal from electric scattering,the difference in behavior ofpulse response is utilized.
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filter/tuner
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Dopplar shift
multilayer,grating
Scale of energy resolution
crystal diffraction
high-resolution
NaI detector
principle and operation in ElectromagneticWaves Spectroscopy
wave length (m)
frequency (Hz)
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(1MHz)109
(1GHz)1012
(1THz)1015
(1PHz)1018
(1EHz)1021
c = !!, k = 2" / !, # = 2"!
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(1mm)10-9
(1nm)10-12
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LF MF HF VHF UHF SHF EHF
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(1µm)
1eV 1keV 1MeV
x-ray $-ray
Wave: A(t)exp(i(#t-k•r))P
band-pass filter, an electronic instrumentation
cavity resonator monochromatordispersion material, grating, crystal lattice
continuous or pulsed wave
# k"!#!! !
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Unified point of view on spectroscopy of electromagnetic wave:Spectrometer operates on ω in long wavelength range, operates on k(= ω /c) in high frequency range.
Frequency tuning in radio-wave band!"#$%&'(
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y(t) = g(t – !)x(!)d!
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InputOutput
Instrument
Mathematical description
t-space
ω-space
Spectrometer for light or x-ray
3-dimensional view of light source
Y1(!)Y
2(k) = G
1(!)G
2(k)X
1(!)X
2(k)
Y(!, k) = G1(!)G
2(k) X(!, k)
Y (!, k) = G(!, k)X(!, k)
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Pulsed wave
Point source
Continuous wave
Finite extension source
Pulsed wave я Point source
Continuous wave я Finite extension source
Study of resonant system essentially needs a short pulsed wave я δ function response
Few bunches э High-brilliance in time domain
Correlations between NRS in energydomain and time domain
NRS Amplitudef(!, k)F(t, k)
Fourier transform
"-ray
!f(!, k)
pulsed SR
F(t, k) !
NRS Amplitude
NR time spectraNR energy absorption spectra
optical theorem
#"!#$%&
#"!#$%&k/4$ Im(f)
power spectrum
Fourier transform Energy difference of hyperfine levels
Theoretical level
Experimental level
Nuclear resonant absorptionspectra in energy domain(Mössbauer spectra)
Nuclear resonant responsefor short x-ray pulse(Quantum beats)
Fourier transformation ofquantum beats (Powerspectra, energy differencebetween energy levels)
Comparing nuclear resonance in 3 worlds
Develop a new experimental technique
configuration of inelastic scattering using NRS
high-resolution monochromator
sample containing NR element
detect time-delayed NRS signal
!
high-resolution monochromator
sample
detector
detector
detector
detector
Foil containing NRS element
monochromator
analyzer
standard configuration of inelastic scattering
detector
sample
First result of inelastic NRS
Develop new applications of traditionalexperimental technique
Control x-ray penetration depth
conclusion• 1) not a simple short bunch, but high-brilliant
short pulse• 2) NRS technique brings us a new energy
resolution frontier in x-ray region• 3) NRS technique combines with pulsed SR let us
be able to do something new where the traditionalMössbauer spectroscopy can not do