The Ionization Balance of the Atmosphere

390 101 2MB

English Pages 47

Report DMCA / Copyright

DOWNLOAD FILE

Polecaj historie

The Ionization Balance of the Atmosphere

Citation preview

"i

r

THE IONIZATION BALANCE OF THE ATMOSPHERE

$0

- l i -A

r

FORDHAM UNIVERSITY GRADUATE SCHOOL

A p r il 2 7 ,

This dissertation prepared under my direction by R n g e r P . V an cou r.

entitled

THE 10N1ZAT1 ON _B_AMNCE OF THE ATMOSPHERE

has been accepted in partial fulfilment of the requirements for the

Degree of

D octor o f P h ilo so p h y

JA 9 .1 ? Ees s (Faculty A dviser)

L

19.51

THE IONIZATION BALANCE OF THE ATMOSPHERE

by

ROGER P . VANCOUR B .S ., Holy D ross C o lle g e , *43 M .S ., B oston C o lle g e , *47

DISSERTATION SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY IN THE DEPARTMENT OF PHYSICS AT FORDHAM UNIVERSITY

NEW YORK 1950

ProQuest N um ber: 10992945

All rights reserved INFORMATION TO ALL USERS The quality of this reproduction is d e p e n d e n t upon the quality of the copy subm itted. In the unlikely e v e n t that the a u thor did not send a c o m p le te m anuscript and there are missing pages, these will be noted. Also, if m aterial had to be rem oved, a n o te will ind ica te the deletion.

uest ProQuest 10992945 Published by ProQuest LLC(2018). C opyright of the Dissertation is held by the Author. All rights reserved. This work is protected against unauthorized copying under Title 17, United States C o d e M icroform Edition © ProQuest LLC. ProQuest LLC. 789 East Eisenhower Parkway P.O. Box 1346 Ann Arbor, Ml 4 8 1 0 6 - 1346

iii "i

r

TABLE OF CONTENTS Page

............................

LIST OF FIGURES.

.............

ACMOl/ffiEDCMENTS I. II . III. IT .

V.

V I. V II. V III.

INTRODUCTION

L

v vi

.............

1

DESCRIPTION OF APPARATUS.. . . ............

3

INTENSITY OF COSMIC RADIATION AND THE RESIDUAL IONIZATION IN BRASS CHAMBERS......

7

DETERMINATION OF THE TRUE VALUE OF THE IONIZATION BY COSMIC RAYS IN THE FREE ATMOSPHERE, WITHOUT S E C O N D A R IE S ............

17

APPROXIMATE DETERMINATION OF THE "AIR RADIATION” (IONIZATION BY GAMMA RAYS FROM THE RADIOACTIVE SUBSTANCES IN THE ATMOS* PHERE) . . . ...........

21

THE IONIZATION PRODUCED BY RADON, THORON AND THEIR DECAY PRODUCTS IN THE ATMOSPHERE.

25

THE IONIZATION BALANCE,............................................

33

SUMMARY........................................

35

BIBLIOGRAPHY

....................

iv

.

LIST OF TABLES. .............. .............................................................

37

J

iv

r

LIST OF TABLES

T able

Page

I ,. Dim ension o f th e f o u r c h a m b e r s ......... ................ II. III. IV . V.

Cosmic ra y i n t e n s i t i e s ( s e a l e v e l , o u td o o rs) i n b r a s s cham bers ( w a ll 2 .5 mm. t h i c k ) .............. D iffe re n c e o f i o n i z a t i o n o b s e r v e d ..

............

3 12 22

Radon e q u i v a l e n t . ..................

29

F r a c tio n x (Rn + decay p r o d u c t s ) .........

31

V

r

LIST OF FIGURES F ig u re

Page

1.

C i r c u it diagram o f a p p a r a t u s . . , . . ........ ............

6

2.

E x tr a p o la tio n o f r e s i d u a l io n i z a t i o n from m easurem ents o f th e f o u r c h a m b e r s ...................

10

R e s id u a l i o n i z a t i o n v s . r a d iu s o f th e i o n i z a t i on ch am b ers.................................

11

3*

4 a . I o n iz a tio n by cosm ic r a y s v s . p r e s s u r e - in a i r ( o u td o o r e x p e r im e n ts ) ................................ ...

15

4 b . I o n iz a tio n by cosm ic r a y s v s . p r e s s u r e ( i n ­ door e x p e r im e n ts ) ...

15

5.

E x tr a p o la tio n o f i o n i z a t i o n by cosm ic r a y s i n th e f r e e atm osphere .............

18

i

r

AOKETOWLEDGBMMTS

The a u th o r w ish es to e x p re s s h i s g r a t i t u d e to D r. V. F . H ess f o r h i s i n s p i r a t i o n a l g u id a n c e .

L

-I

1

r

I . INTRODUCTION

W ith in th e l a s t two d e c a d e s , e x te n s iv e r e s e a r c h o f th e v a r i a t i o n s o f cosm ic ra y i n t e n s i t y w ith tim e , geom agnetic l a t i t u d e , b a ro m e tric p r e s s u r e , te m p e ra tu re and a l t i t u d e h a s been c a r r i e d o u t .

However, we have in c o m p le te know ledge o f

th e i o n i z a t i o n b a la n c e o f th e a tm o sp h e re .

Over th e o c e a n s,

cosm ic r a d i a t i o n i s p r a c t i c a l l y th e o n ly i o n iz in g agency and o v er th e c o n t in e n t s , th e i o n i z a t i o n o b serv ed i s due m ostly t o th e r a d io a c tiv e s u b s ta n c e s i n th e ground and i n th e a i r .

The v a r i a t i o n s o f io n i z a t i o n o v er th e ocean a re

d u e, p r i n c i p a l l y t o v a r i a t i o n s o f te m p e ra tu re i n th e lo w er atm osphere and o f b a ro m e tric p r e s s u r e .

A lso , f l u c t u a t i o n s

o f cosm ic ra y i n t e n s i t y w ith tim e and w ith geom agnetic l a ­ t i t u d e have b een fo u n d . The a b s o lu te i n t e n s i t y o f cosm ic r a d i a t i o n a t s e a l e v e l r e p o r te d by d i f f e r e n t a u th o rs v a r ie s w ith in wide lim its .

These v a lu e s a re o b ta in e d in i o n i z a t i o n cham bers

f i l l e d w ith a i r and re d u c e d to norm al te m p e ra tu re and p re ssu re .

At geom agnetic l a t i t u d e s beyond th e 11knee M, th e

r e p o r te d v a lu e s ran g e from 1 .8 t o 2 .8 I f o r u n s h ie ld e d i o n i z a t i o n cham bers ( t,I H d e n o te s th e number o f io n p a i r s 3 produced i n a i r p e r cm. , p e r s e c . ) . From th e I n t e n s i t y v s . a l t i t u d e c u rv e , K o lh o e r s te r o b ta in e d a v a lu e o f 2 .8 I . 1 I n H o lla n d , J . Clay and P . H. Clay , u s in g u n sc re e n e d a p L

_]

2

r

“i p a r a t u s , found 1 .6 3 I f o r a chamber f i l l e d w ith a i r a t a t o m osph eric p r e s s u r e and 15 C. Many a u th o rs d id n o t ta k e i n ­ t o a c c o u n t th e in c r e a s e o f i o n i z a t i o n by s e c o n d a rie s p roduced i n th e w a lls o f th e cham ber.

I t i s b e lie v e d t h a t th e a d d i­

t i o n a l io n p ro d u c tio n by s e c o n d a r ie s i n a t h i n - w a lle d b r a s s chamber i s s m a ll, p erh ap s o n ly a few p e r c e n t o f th e t o t a l e ffe c t. The d is c r e p a n c ie s betw een th e r e s u l t s o f v a r io u s au­ t h o r s c o u ld l a r g e l y be due to th e f a c t t h a t e f f e c t s o f l o c a l gamma-rays were n o t d e te rm in e d a c c u r a te ly enough.

I n some

c a s e s , th e r e s i d u a l i o n i z a t i o n w hich i s due t o r a d io a c tiv e im p u r it ie s i n th e w a lls o f th e chamber was o v e r- o r u n d e r­ e s tim a te d ; i n o th e r c a s e s , th e r e d u c tio n o f o b serv ed io n ­ i z a t i o n i n h ig h p r e s s u r e i n a i r may n o t be s u f f i c i e n t l y a c c u r a te and, f i n a l l y , e r r o r s i n th e d e te r m in a tio n o f sm a ll c a p a c ita n c e s o f some in s tru m e n ts o r a la c k o f s a t u r a t i o n i n th e i o n i z a t i o n cham bers may have b een q u ite l a r g e .

L

_J

r

I I . DESCRIPTION*OF APPARATUS

F our i o n i z a t i o n cham bers o f c y l i n d r i c a l sh a p e, made o f y e llo w b r a s s w ith a w a ll th ic k n e s s o f 2 .5 mm., were u se d in c o n ju n c tio n With th e i o n i z a t i o n m e te r d e v is e d by 0 . G ish, 2

K. 1 . Sherman and V, F . H ess . c a lly s im ila r.

The cham bers a re g e o m e tri­

(The h e ig h t i s e q u a l t o tw ic e th e d ia m e te r

o f th e cham b er).

A ll f o u r cham bers a re a i r t i g h t and can

be e v a c u a te d o r f i l l e d w ith any gas th ro u g h a Hoke n e e d le v a lv e . TABU! I . D im ensions o f th e F our Chambers. Chamber

I II III IV

Volume (W l cm-? 43680 13173 4888 1645

I n n e r S u rfa c e (AsrlOr2***) cm2 7070 3243 1674 811

R adius (v)

cm 1 5 .0 1 0 .1 6 7 .3 0 5 .0 8

%

0.1618 0.2462 0.3 4 2 5 0.4930

The ir o n house h a s f o u r w a lls c o n s tr u c te d o f ir o n b lo c k s 10cm. t h i c k .

The to p and bottom o f th e ir o n h o u se

c o n s i s t s o f ir o n s h e e ts b u i l t 16 s h e e ts t h i c k t o g iv e an appro x im ate th ic k n e s s o f 10cm.

The f r o n t w a ll o f th e ir o n

house h a s an o p en in g th ro u g h w hich one can view th e e l e c t ­ ro m e te r.

When th e i o n i z a t i o n chamber i s p la c e d i n th e ir o n

h o u se , th e t o t a l i o n i z a t i o n o b serv ed i s due t o th e r e s i d u a l io n i z a t i o n o f th e chamber and cosm ic r a y s s in c e th e w a lls o f th e ir o n house a r e t h i e k enough to a b so rb p r a c t i c a l l y L

_l

p

*1

a l l gam m a-rays. The in n e r e l e c t r o d e o f e a ch chamber i s a m b e r-in s u la te d

and i s d i r e c t l y co n n ected t o th e f i b e r system o f a Lindemann e le c tr o m e te r w hich i s mounted i n a hou sin g *

The h o u sin g i s

c o n s tr u c te d so t h a t i t f i t s e x a c tly t o th e to p o f each chamber w hich a r e s e t i n a v e r t i c a l p o s i t i o n .

The guard

r i n g o f ea ch chamber and th e e le c tr o m e te r h o u s in g a r e con­ n e c te d w ith a b a t t e r y s u p p ly in g 135 v o l t s .

The c e n te r p o in t

o f th e q u a d ra n t b a t t e r y i s k e p t a t t h i s same p o t e n t i a l .

A

n e e d le c o n ta c to r i s u se d t o co n n e ct o r d is c o n n e c t th e f i b e r system from th e 135 v o l t b a t t e r y .

When th e e le c tr o m e te r

n e e d le and th e in n e r e l e c t r o d e a r e co n n ected to t h i s 135 v o l t su p p ly by th e n e e d le c o n t a c t o r , th e e le c tr o m e te r n e e d le i s a t i t s z e ro p o s i t i o n . a t ground p o t e n t i a l .

The w a ll of each chamber i s k e p t

When th e c o n ta c to r i s w ithdraw n, th e

e le c tr o m e te r n e e d le b e g in s t o f l o a t and th e r a t e of i t s movement i s p r o p o r tio n a l t o th e i o n i z a t i o n c u r r e n t flo w in g betw een th e d is c h a r g in g in n e r e l e c t r o d e and th e grounded w a ll cham ber. I n th e e x p e rim e n ts t o be d is c u s s e d , th e fln u ll-m e th o d n was u s e d .

In t h i s m ethod, a 3 - v o l t a u x i l i a r y b a t t e r y w ith

a p o te n tio m e te r and a p r e c i s i o n v o ltm e te r w ith a 3 - v o l t ran g e was u s e d .

Thus, we were a b le to add any v o lta g e from

0 t o - 3 v o I ts t o th e 1 3 5 - v o lt sweep v o lta g e w hich in d u ced an o p p o s ite ch arg e on th e f i b e r system to keep th e e le c tr o m e te r n e e d le c lo s e to th e ze ro p o s i t i o n .

S in ce th e in n e r e l e c t r o d e

r

xs k e p t p r a c t i c a l l y a t z e ro p o t e n t i a l , i n s u l a t i o n le a k a g e i s a c t u a l l y a v o id e d .

-j

T his co m p en satin g v o lta g e i s re a d a t th e

end o f a m easurem ent and th e le n g th o f tim e f o r th e m easure­ ment i s r e c o r d e d .

T h is co m p en satin g v o lta g e d iv id e d by th e

tim e in se co n d s and m u lt ip lie d by a c a r e f u l l y d e te rm in e d r e d u c tio n f a c t o r g iv e s th e i o n i z a t i o n , q , e x p re s s e d i n io n 3 p a i r s p e r cm p e r s e c . The c a p a c ita n c e s and in d u c tio n c o e f f i c i e n t s o f a l l f o u r cham bers w ith th e e le c tr o m e te r were d e te rm in e d i n 1948 by means o f a Wulf v a r ia b le c o n d e n se r c a l i b r a t e d w ith a G-. E . c a p a c ita n c e b rid g e i n th e d e p a rtm e n t o f T e r r e s t r i a l Magne­ tis m and C arn eg ie I n s t i t u t e o f W ashington, D. C.

— (v )—

conPS*SAriw*/ c/'««m/V

CALlBRATioV c i/fc u ir

HOas*A/e-

sr/tMfl

B3= 3.0* /33* r3* 9wa

C H fiM B ta

•Fig. 1 , C i r c u it diagram o f a p p a r a tu s .

I I I . INTENSITT OF COSMIC RADIATION AND THE RESIDUAL IONIZA* TION IN BRASS CHAMBERS

The i o n i z a t i o n o f th e atm osphere a t s e a l e v e l , o v e r la n d , i s produced "by th e a lp h a , b e t a and gamma r a y s from th e r a d i o a c t i v e p ro d u c ts i n th e s o i l and in th e atm o sp h ere, and, t o a l e s s e r e x t e n t , by cosm ic r a d i a t i o n .

I f th is

i o n i z a t i o n i s m easured i n a h e r m e tic a lly s e a le d v e s s e l f i l l e d w ith a gas f r e e o f ra d o n , th e t o t a l i o n i z a t i o n i s due t o : (1 ) o c c a s io n a l a lp h a r a y s from r a d io a c tiv e im p u ri­ t i e s i n th e m e ta l o f th e cham ber, nam ely, r e s i d u a l i o n i z a ­ t i o n , qQ, ( 2 ) gamma r a y s from th e r a d io a c tiv e s u b s ta n c e s i n th e s o i l ,

(3 ) gamma r a y s from th e r a d i o a c t i v e decay

p ro d u c ts o f ra d o n , th o ro n and a c tin o n i n th e atm o sp h ere, q^ aiid (4 ) cosm ic r a y s , q ^ . q - ^ » '» *• = i^r i* f=- lpPi A/ = 11 - 1p - 4pp=- pp v

r

r

#

r* Lf



(5)

where q d e n o te s th e t o t a l i o n i z a t i o n o b serv ed a t th e p r e s ­ su re p . d ire c tly .

I t i s more a c c u r a te to o b ta in d ^ /d p from th e graph F ig . 4 ( a ) shows two sample c u rv e s o b ta in e d o u t­

d o o rs w ith a i r i n th e cham ber.

Curve I c o rre sp o n d s to th e

case when th e ir o n house was c l oosedv s e d ^ -th t h aa t i s , 10 cm. Fe

F ig . 4 a.

© N> •M

[