A nuclear-frequency modulation spectrometer for Moessbauer studies

Thesis/Dissertation · Fri Jan 01 04:00:00 EST 1988

OSTI ID:7005564

Reittinger, P W

In this work a spectrometer was constructed which measured the resonant absorption of {gamma}-radiation by a ferromagnetic as a function of the frequency of a time varying magnetic field to which the absorber was exposed. This Nuclear Frequency Modulation Spectrometer (NFMS) was used to study the Moessbauer isotope {sup 57}Fe in ferromagnetic and paramagnetic foils. Also developed was a fast multi-channel scaler, which extended the capabilities of the NFMS to the measurement of the lifetime of the phenomenon induced in the absorber by the fields. The instrument's operation was based upon the observed fact that a ferromagnetic {gamma}-ray absorber exhibited a frequency dependent hyperfine structure when it interacted with a radio-frequency field. Sideband transitions were found to be displaced from their unperturbed parents by integral multiples of the frequency of the applied field. This inherent tunability of the absorption cross section was then limited by the stability and resolution with which a signal frequency was selected. By contrast, the tunability of a conventional Moessbauer spectrometer is limited by the stability and reproducibility with which a mechanical motion can be generated. With this instrument, very precise measurements of sideband linewidths and nuclear isomer shifts between sources and absorbers were obtained. It was discovered that the sideband linewidths measured with the NFMS were as much as 30% narrower than those measured with a conventional Moessbauer spectrometer. Additionally, there was structure in the NFM spectra of a paramagnetic stainless steel with defies a classical description.

• Research Organization: Texas Univ., Dallas, TX (USA)
• OSTI ID: 7005564
• Country of Publication: United States
• Language: English

Related Subjects

440000* -- Instrumentation
440103 -- Radiation Instrumentation-- Nuclear Spectroscopic Instrumentation
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY
47 OTHER INSTRUMENTATION
CONSTRUCTION
DATA
EVEN-ODD NUCLEI
EXPERIMENTAL DATA
GAMMA SPECTROMETERS
INFORMATION
INTERMEDIATE MASS NUCLEI
IRON 57
IRON ISOTOPES
ISOTOPES
MEASURING INSTRUMENTS
MEASURING METHODS
MOESSBAUER SPECTROMETERS
NUCLEAR PROPERTIES
NUCLEI
NUMERICAL DATA
SPECTROMETERS
STABLE ISOTOPES