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Neutrons and other heavy particles in cosmic radiation of the stratosphere
NOTES FROM THE BARTOL RESEARCH FOUNDATION. N E U T R O N S A N D O T H E R HEAVY P A R T I C L E S I N COSMIC R A D I A T I O N OF T H E S T R A T O S P H E R E . * BY L. H. R U M B A U G H and G. L. L O C H E R .
The apparatus, which was also carried on the second National Geographic U. S. Army Air Corps Stratosphere flight, was designed to test for the presence of radiations of various kinds--in particular, alpha particles, protons, and neutrons-in the incoming radiation. Specially prepared photographic plates shielded, of course, from light, were exposed to the cosmic radiation. A portion of the area was left free for the purpose of recording any heavy ionizing cosmic-ray particles that might occur in the upper atmosphere, without regard to their origin. Portions of the plates were covered with paraffin to record possible cosmic-ray neutrons which would manifest themselves by the ejection of recoil protons. Other portions of the plates were covered with elements of various types in which cosmic-rays might produce nuclear disintegrations with the accompaniment of heavy particles, such as alpha particles and protons. In all cases, the intent was to seek for the final heavy particle radiations in the emulsion of the photographic film by microscopic examination. The results are shown in detail in the original publication (National Geographic Society Contributed Technical Papers, Stratosphere Series, No. 2), and it will suffice to say that the only entities of the kind stated which revealed themselves were neutrons, and an upper limit to the neutron flux was fixed at o.2 neutrons per square centimeter per second. The further conclusion reached is to the effect that at the altitude reached by the balloon, neutrons constitute a considerable * Condensed from a paper published in full in the National Geographic Society Contributed Technical Papers, Stratosphere Series No. 2, pp. 32-36 (1936) . 414
March, '939.]
ThE
415
BARTOL RESEARCH FOUNDATION.
fraction of the cosmic radiation in number, though n o t in energy.
T H E SOLUTION OF V 2 ¢ - (x/c~)O~o/Ot~ = -
a.*
BY
W. F. G. SWANN.
P e r h a p s some apology seems necessary for giving a new m e t h o d of arriving at the solution of the a b o v e equation whose solution is so well known. However, it is the experience of the writer t h a t the usual forms of solution have in t h e m certain elements which a p p e a r s o m e w h a t artificial to m a n y physicists; and, for this reason a solution which proceeds in a straightforward m a n n e r m a y be of service? Starting then with the equation (I/c2)Oz~/Ot 2 = -
O2~/Ox 2 + O2¢/Oy 2 + O2~/Oz ~- -
a,
(I)
r = t~=r/c,
(2)
we m a k e the transformation = x,
~ = y,
where r 2 ~ x 2 + O
~ = z,
p = r,
y2 _~_ Z'.. W e then find, immediately,
0:3:: I ( O r )
O
O
c
a~-
a~ ~ = r c o r - o ~ T
ax-a~
Ox
x O
0
~ 0
.~cOr ....
Analogous results hold for O/Oy and O/Oz, so t h a t 3
3 ~= }
Ox
O}
a --
Oz
pc Or '
a ....
O~
O Oy
~a =7
-
-
-
-
pc Or
;
also
OTtO On pc Or '
a/at
(3)
= a/0r.
* Reprinted from the American Physics Teacher, 5, 27 (I937). 1 The solution usually given is that of G. Kirchhoff, Berl. Sitz., 641 (1882). Another proof has been given by Max Mason, Phys. Rev., 15, 312 (192o). The proof now given was developed by the writer for use in his classes on electrodynamics. As it is on the point of being submitted for publication, another proof following different lines has made its appearance: see S. Ballantine, J. Frank. Inst. 22x, 469 (1936).
The apparatus, which was also carried on the second National Geographic U. S. Army Air Corps Stratosphere flight, was designed to test for the presence of radiations of various kinds--in particular, alpha particles, protons, and neutrons-in the incoming radiation. Specially prepared photographic plates shielded, of course, from light, were exposed to the cosmic radiation. A portion of the area was left free for the purpose of recording any heavy ionizing cosmic-ray particles that might occur in the upper atmosphere, without regard to their origin. Portions of the plates were covered with paraffin to record possible cosmic-ray neutrons which would manifest themselves by the ejection of recoil protons. Other portions of the plates were covered with elements of various types in which cosmic-rays might produce nuclear disintegrations with the accompaniment of heavy particles, such as alpha particles and protons. In all cases, the intent was to seek for the final heavy particle radiations in the emulsion of the photographic film by microscopic examination. The results are shown in detail in the original publication (National Geographic Society Contributed Technical Papers, Stratosphere Series, No. 2), and it will suffice to say that the only entities of the kind stated which revealed themselves were neutrons, and an upper limit to the neutron flux was fixed at o.2 neutrons per square centimeter per second. The further conclusion reached is to the effect that at the altitude reached by the balloon, neutrons constitute a considerable * Condensed from a paper published in full in the National Geographic Society Contributed Technical Papers, Stratosphere Series No. 2, pp. 32-36 (1936) . 414
March, '939.]
ThE
415
BARTOL RESEARCH FOUNDATION.
fraction of the cosmic radiation in number, though n o t in energy.
T H E SOLUTION OF V 2 ¢ - (x/c~)O~o/Ot~ = -
a.*
BY
W. F. G. SWANN.
P e r h a p s some apology seems necessary for giving a new m e t h o d of arriving at the solution of the a b o v e equation whose solution is so well known. However, it is the experience of the writer t h a t the usual forms of solution have in t h e m certain elements which a p p e a r s o m e w h a t artificial to m a n y physicists; and, for this reason a solution which proceeds in a straightforward m a n n e r m a y be of service? Starting then with the equation (I/c2)Oz~/Ot 2 = -
O2~/Ox 2 + O2¢/Oy 2 + O2~/Oz ~- -
a,
(I)
r = t~=r/c,
(2)
we m a k e the transformation = x,
~ = y,
where r 2 ~ x 2 + O
~ = z,
p = r,
y2 _~_ Z'.. W e then find, immediately,
0:3:: I ( O r )
O
O
c
a~-
a~ ~ = r c o r - o ~ T
ax-a~
Ox
x O
0
~ 0
.~cOr ....
Analogous results hold for O/Oy and O/Oz, so t h a t 3
3 ~= }
Ox
O}
a --
Oz
pc Or '
a ....
O~
O Oy
~a =7
-
-
-
-
pc Or
;
also
OTtO On pc Or '
a/at
(3)
= a/0r.
* Reprinted from the American Physics Teacher, 5, 27 (I937). 1 The solution usually given is that of G. Kirchhoff, Berl. Sitz., 641 (1882). Another proof has been given by Max Mason, Phys. Rev., 15, 312 (192o). The proof now given was developed by the writer for use in his classes on electrodynamics. As it is on the point of being submitted for publication, another proof following different lines has made its appearance: see S. Ballantine, J. Frank. Inst. 22x, 469 (1936).