Radioactivity and Nuclear Reactions Applied to Astrophysics, Particle
Physics, Archeology, and the Study of Art Works 1947-67
Radioactivity applied to
archaeology and to the study of works of art
The first application of neutron activation analysis to the study of
archaeological materials was made at BNL. In some Greek terra cotta
figurines it was found that the trace impurity compositions fall into
patterns which are correlated to locations of origin and manufacture.
Ancient commerce in Roman Aretine pottery, in South Arabian pottery, and in
Mayan pottery has been traced. An extensive study of ancient glass has
revealed many facts concerning the technology of its manufacture. A number
of institutions have now adopted neutron activation techniques for work in
these areas. It was at BNL that activation autoradiography was for the first
time applied to investigations of works of art such as paintings and to
recovery of images from badly faded historic photographs. In paintings, the
different pigments give rise to radiations decaying with different
half-lives, and a sequence of autoradiographs may provide information about
layers of pigments used by the artist and about his techniques of
application.
E. V. Sayre, "Some Ancient Glass Specimens with Compositions of
Particular Archaeological Significance," BNL 879 (T-354), July 1964.
E. V. Sayre and H. N. Lechtman, "Neutron Activation Autoradiography of Oil
Paintings," Studies in Conservation 13, 161 (1968).
Lepton conservation
The neutrino capture reaction, n+ Cl37
® Ar37 + e-, was shown not
to proceed with the antineutrinos emitted by a nuclear reactor, thus
experimentally demonstrating that neutrinos and antineutrinos differ in
their interactions with nuclei. This result is one of the prime experimental
facts supporting the principle of lepton conservation.
R. Davis, "An Attempt to Observe the Capture of Reactor Neutrinos in
Chlorine-37," Proc. 1st UNESCO Conf., I, 728 (1958).
Application of radioactivity and
nuclear reactions to astrophysics
Measurements have been made of the stable and radioactive products
produced in meteorites by cosmic radiation. From these measurements and from
the high energy production cross sections for these products it is possible
to obtain information about the cosmic ray intensity. Two important
conclusions have been made: 1) the intensity of cosmic radiation has been
constant in time, that is, the average intensity over the last 400 years is
the same as the average intensity over the last 400,000 years; 2) the
intensity of the cosmic. Radiation near the earth is about 20 percent lower
than the intensity at several earth-sun distances from the sun.
The Cl36-Ar36 method used extensively for
determining accurate cosmic ray exposure ages of meteorites originated at
BNL.
The time interval which elapsed between formation of the elements and
formation of an earth capable of retaining atmosphere was deduced to be 2.7
x 108 years. This number is based on a BNL measurement of the
half-life of I129, 1.72 x 107 years, and on the
justifiable assumption that most of the Xe129 now present on
earth originated from that part of the original I129 still
remaining to decay after the earth was formed.
An experiment is underway to test the present theory of the solar energy
generation process by observation of the neutrino radiation emitted from the
sun. The method used depends upon measurement of the neutrino-capture
reaction n + Cl37
® Ar37 + e- in a detection system containing
610 tons of the chlorine-containing compound C2Cl4.
Observations show that the neutrino capture rate in the detector is at least
a factor of seven below that expected from current theory.
S. Katcoff, O. A. Schaeffer, and J. M. Hastings, "Half-Life of I129 and
the Age of the Elements," Phys. Rev. 82, 688 (1951).
O. A. Schaeffer, R. Davis Jr., R. W. Stoenner, and D. Heymann, "The Temporal
and Spatial Variation in Cosmic Rays," Proc. Intl. Conf. on Cosmic Rays,
Jaipur, India, 3, 480 (1963).
R. Davis Jr. and D. S. Harmer, "Solar Neutrino Detection by the Cl37-Ar37
Method," Proc. Informal Conf. on Experimental Neutrino Physics, CERN
65-32 (Geneva) 1965.
R. Davis Jr. and D. S. Harmer, "Solar Neutrinos," Die Umschau 2,
56 (1966).
Last Modified: June 28, 2012
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