328
14.
ARTIFICIAL TRANSMUTATION
-
neutron were found, (2) a neutron was ejected leaving berylliumeight and (3) a proton was ejected leaving radio—active lithium—
eight which became beryllium-eight after the emission of a negative
electron.
Thus, a variety of reactions are possible when a given target is
bombarded by particles of one kind. As illustrated by the case
-
tr0n emission is greatest, that of proton emission is next and that
of alpha emission is least. The neutron emission may be 100,000
times as probable as the other two.
,
Many transmutations have been produced With targets of the
heavy as well as of the light elements. The residual nuclei are
‘
_
stable in certain cases and radioactive in others.
A positron
is emitted in the reaction
‘
6C12 + 1H2 ——> 7N13* + On1 : 7N13* —-> 6C13 + +1€ (14—26)
whereas the bo”mbardment of sodium With deuterons gives
11N323 + 1H2 +> 11Na24* + 1H1 !
_
'
11Na24* ——> 12Mg24 + _16 + 7(14—27)
_
The negative electrons (__e) have a maximum of energy of 3 Mev
and the gamma rays (fy) have an energy of at least 3 Mev (pene—
’
trating). The half-life of the radio—sodium (Na24*) is approximately fteen hours. One microampere of deuteron current at
1.75 MeV can give thirty million transmutations into radio-sodium
_
É
each second.
This material may be used in medical applications
instead of natural radio-active substances.
‘
_
The excited states of a residual nucleus are the same, irrespec—
'
_
tive of the method of production of the nucleus. For example, the.
carbon nucleus 6C12 in the transmutation
'
7N14 + 1H2 -—> (;C12 + 2H64
(14—28) ,
.
has an excitation energy
=
El —- EO : 13.2 — 8.9 = 4.3 MeV.
Ï
In the reaction _
,
_
,
,
=‘4Be9 + 2He4 ——> ($C-12 + (ml + 'y,
6C12
rays whose three components have energies Of
_
2-7) 4-2_and 6.7 Mev.
The value 4.2 is in good agreement with 4.3 ..
_
the preceding reaction.
.
_
,
’
14.
ARTIFICIAL TRANSMUTATION
-
neutron were found, (2) a neutron was ejected leaving berylliumeight and (3) a proton was ejected leaving radio—active lithium—
eight which became beryllium-eight after the emission of a negative
electron.
Thus, a variety of reactions are possible when a given target is
bombarded by particles of one kind. As illustrated by the case
-
tr0n emission is greatest, that of proton emission is next and that
of alpha emission is least. The neutron emission may be 100,000
times as probable as the other two.
,
Many transmutations have been produced With targets of the
heavy as well as of the light elements. The residual nuclei are
‘
_
stable in certain cases and radioactive in others.
A positron
is emitted in the reaction
‘
6C12 + 1H2 ——> 7N13* + On1 : 7N13* —-> 6C13 + +1€ (14—26)
whereas the bo”mbardment of sodium With deuterons gives
11N323 + 1H2 +> 11Na24* + 1H1 !
_
'
11Na24* ——> 12Mg24 + _16 + 7(14—27)
_
The negative electrons (__e) have a maximum of energy of 3 Mev
and the gamma rays (fy) have an energy of at least 3 Mev (pene—
’
trating). The half-life of the radio—sodium (Na24*) is approximately fteen hours. One microampere of deuteron current at
1.75 MeV can give thirty million transmutations into radio-sodium
_
É
each second.
This material may be used in medical applications
instead of natural radio-active substances.
‘
_
The excited states of a residual nucleus are the same, irrespec—
'
_
tive of the method of production of the nucleus. For example, the.
carbon nucleus 6C12 in the transmutation
'
7N14 + 1H2 -—> (;C12 + 2H64
(14—28) ,
.
has an excitation energy
=
El —- EO : 13.2 — 8.9 = 4.3 MeV.
Ï
In the reaction _
,
_
,
,
=‘4Be9 + 2He4 ——> ($C-12 + (ml + 'y,
6C12
rays whose three components have energies Of
_
2-7) 4-2_and 6.7 Mev.
The value 4.2 is in good agreement with 4.3 ..
_
the preceding reaction.
.
_
,
’