322
14.
ARTIFICIAL TRANSMUTATION
»
‘
disintegrations) the half-period is a characteristic of the
ter.
The positron -emitter was identied by chemical means,
18
"
'
despite the exceedingly small number of atoms available. To do
,
this, stable elements near aluminum were added to an active
sample. Then, upon
chemical separation, a comparatively small
number of atoms of the positron emitter and a large number of
fg
atoms of et stable isotope of the same element were precipitated together. The positrons, in this case, were found to be emitted by
the phosphorus deposit and not by other precipitates. The reac—
tion may, therefore, be written as
13A127 + 2He4 ——> 15P3°* + on1
—-> 14Sî30 + +1e.
(14—15)
'
The asterisk is,used to denote a radioactive substance, in this case
“radiophosphorus.”
'
Many radioactive substances have been articially produced
by irradiation of the elements with energetic alpha particles,
deuterons, protons and neutrons. In some cases the ej ected particle
is a positron and in others it is a negative electron. Examples will
be given later in this chapter. For collected results see reference 19.
Negative electrons are emitted from elements whose atomic weight
is greater than that of the stable isotope. The opposite is true when
positronS ate emitted.
'
Gamma rays are frequently emitted during articial radioactive
disintegrations. They decrease in intensity at the same rate as
that of the accompanying electron emission and, consequently, are
not c0nfuSed with the gamma rays emitted during the primary
nuclear transmutation.
It is assunied that when a radioactive
isotope diSintegrates With the emission of an electron, the nal
be left in an excited state fr0m which it shifts into
…
_
groundstate With the emission of gamma rays.
_
,
Aglvenradioactive isôtope has a characteristic half—life and
with a
energydlstrlbutionHence astudyoftïhe,electronemission Wh1Ch
f@“OWsanuclear reactmnservesasa vaiuabie indicator mthe
dlSCŒVefedbYetectmgthesubsequentelectronactiv1ty
measure@fthnumbef0ffeSIduainucleiproduced , t
14.
ARTIFICIAL TRANSMUTATION
»
‘
disintegrations) the half-period is a characteristic of the
ter.
The positron -emitter was identied by chemical means,
18
"
'
despite the exceedingly small number of atoms available. To do
,
this, stable elements near aluminum were added to an active
sample. Then, upon
chemical separation, a comparatively small
number of atoms of the positron emitter and a large number of
fg
atoms of et stable isotope of the same element were precipitated together. The positrons, in this case, were found to be emitted by
the phosphorus deposit and not by other precipitates. The reac—
tion may, therefore, be written as
13A127 + 2He4 ——> 15P3°* + on1
—-> 14Sî30 + +1e.
(14—15)
'
The asterisk is,used to denote a radioactive substance, in this case
“radiophosphorus.”
'
Many radioactive substances have been articially produced
by irradiation of the elements with energetic alpha particles,
deuterons, protons and neutrons. In some cases the ej ected particle
is a positron and in others it is a negative electron. Examples will
be given later in this chapter. For collected results see reference 19.
Negative electrons are emitted from elements whose atomic weight
is greater than that of the stable isotope. The opposite is true when
positronS ate emitted.
'
Gamma rays are frequently emitted during articial radioactive
disintegrations. They decrease in intensity at the same rate as
that of the accompanying electron emission and, consequently, are
not c0nfuSed with the gamma rays emitted during the primary
nuclear transmutation.
It is assunied that when a radioactive
isotope diSintegrates With the emission of an electron, the nal
be left in an excited state fr0m which it shifts into
…
_
groundstate With the emission of gamma rays.
_
,
Aglvenradioactive isôtope has a characteristic half—life and
with a
energydlstrlbutionHence astudyoftïhe,electronemission Wh1Ch
f@“OWsanuclear reactmnservesasa vaiuabie indicator mthe
dlSCŒVefedbYetectmgthesubsequentelectronactiv1ty
measure@fthnumbef0ffeSIduainucleiproduced , t