Measuring instrument analyzes mechanical vibrations in transducers at amplitudes in the range of a few to 100 angstroms. This instrument utilizes the Mossbauer effect, the phenomenon of the recoil-free emission and resonant absorption of nuclear gamma rays in solids

Roughton, N. A.

English

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September 1967	 Brief 67-10339 
NASA TECH BRIEF 
NASA Tech Briefs are issued to summarize specific innovations derived from the U.S. space program, 
to encourage their commercial application. Copies are available to the public at 15 cents each 
from the Clearinghouse for Federal Scientific and Technical Information, Springfield, Virginia 22151. 
Vibration Analysis Utilizing Mossbauer Effect 
1 Mc	 S2 
Time 
Generator
[Pulse	 Scaler	 Timer	 Scaler Amplifier 1.101 Height	 H I I Analyzer  
.
rays emitted by the source, is connected through the 
amplifiers to a pulse height analyzer. The output of 
the analyzer is connected to scaler I. The output of 
the ac gate is connected through contacts b-c of switch 
51 to both scalers, which are connected to timers. 
However, neither timer is operative during ac gate 
operation. The time base generator is connected 
through an amplifier and contacts b-c of switch S2 
during ac gate operation to scaler 2 to obtain a time 
base count measure. The total time during which 
scaler 2 is actuated by the gate pulse may be accurately 
determined in terms of the number of timing pulses 
counted by scaler 2. Thus, the number of counts per 
unit of time received by scaler 1 through the pulse 
height analyzer may be accurately measured. 
The source used was cobalt-57 diffused into a pal- 
ladium matrix. The 14.4 keV gamma ray, which ex- 
hibits Mossbauer behavior, arises from the first 
excited state of iron-57, the daughter product of 
-	 -	
-	 (continued overleaf) 
This document was prepared under the sponsorship of the National	 Government assumes any liability resulting from the use of the 
Aeronautics and Space Administration. Neither the United States 	 information contained in this document, or warrants that such use 
Government nor any person acting on behalf of the United States 	 will be free from privately owned rights. 
An instrument has been designed for the measure-
ment of mechanical vibrations in transducers at ampli-
tudes in the range of a few to 100 angstroms. Vibra-
tion measurements in this amplitude range cannot be 
accomplished by ordinary optical means. This instr.u-
ment utilizes the Mossbauer effect, the phenomenon 
of the recoil-free emission and resonant absorption of 
nuclear gamma rays in solids, which was discovered by 
Rudolf L. Mossbauer in 1957. 
The instrumental setup, shown in the diagram, 
includes a Mossbauer gamma ray source fixed to a 
drive unit consisting of a piezoelectric transducer, a 
standard collimator, a gamma ray absorber, and a 
detector. The detector is preferably a cleaved thal-
lium-activated sodium iodide crystal with a 1 mil 
beryllium window mounted on a standard photomul-
tiplier tube. The drive unit is energized by a standard 
audio oscillator, which is also connected to the ac gate 
control system. The detector, responsive to the gamma
https://ntrs.nasa.gov/search.jsp?R=19670000339 2020-03-11T21:05:18+00:00Z
cobalt-57. When the absorber is composed of unex-
cited iron-57 in palladium, full resonance absorption 
can occur; i.e., maximum absorption occurs for zero 
relative velocity between source and absorber. If the 
absorbing iron-57 is diffused in stainless steel, partial 
resonance occurs; i.e., the ground state of the absorber 
is shifted with respect to the ground state of the 
source. For this case (partial resonance), the zero 
velocity count corresponds to some point intermediate 
to resonance absorption and nonresonance absorp-
tion. If the absorbing iron is in a chemical compound, 
e.g., FeSO4.7H20 in which the iron nucleus resides 
in a local electric field, the excited state is split into 
two components. In this case two absorption maxima 
are found at proper relative velocities (quadrupole 
split resonance). If the absorber is composed of raw 
iron, the nucleus is influenced by the presence of a 
local magnetic field, thereby splitting the excited state 
into four components and the ground state into two 
components. This case results in six resonance absorp-
tion lines due to the Zeeman effect. The instrument 
utilizes these phenomena for analyzing vibration. A 
theoretical method for utilizing each case was estab-
lished and experimentally verified. 
Note: 
A discussion of this development is given in "The 
Mossbauer Effect and Its Application to Measuring 
Technology", by Helmut G. Lackner, NASA SP-132, 
for sale by the U.S. Government Printing Office, 
Washington, D.C. 20402; price $1.00. Inquiries may 
also be directed to: 
Technology Utilization Officer 
Marshall Space Flight Center 
Huntsville, Alabama 35812 
Reference: B67-10339 
Patent status: 
No patent action is contemplated by NASA. 
Source: Norbert A. Roughton 
(MFS-1 1974)
is 
S 
Brief 67-10339	 Category 01


Vibration analysis utilizing Mossbauer effect

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