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Table 784. Calculated Mass Absorption Coefficients

Table 784. Calculated Mass Absorption Coefficients

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T A B L E 784.-CALCULATED



MA SS A B SOR PTION C O E F F I C I E N T S (concluded)



K series



::



0



2

7



C:



Material



,010



.020



,040



.080



.15



,1269

,1364

.1411

.1466

,1492

.1570

.1587

.1661

.1685

.1785

2 0 13

2508

2575

2878

,2973

,3049

.3210

.3320

.3406

.3612



.3873

.4680

.497 1

S581

.5950

.6397

.6606

.7190

7332

.7959

,9689

1.3152

1.3614

1.5647

1.6253

1.6759

1.7806

1.8491

1.8609

1.9814



1.8412

2.3331

2.5023

2.8718

3.0958

3.3434

3.4660

3.7952

3.8080

4.1654

5.0766

6.7235

6.9253

7.7673

8.0105

8.1957



,1052

.1170

.1151

.I201

.1133



.1337



.1643

,1819

-1747

.-.

..

.1806

.l708



42 Molybdenum

46 Palladium

47 Silver

50 Tin

52 Tellurium

53 Iodine

54 Xenon

56 Barium

58 Cerium

60 Neodymium

65 Terbium

73 Tantalum

74 Tungsten

78 Platinum

79 Gold

80 Mercury

82 Lead

83 Bismuth

90 Thorium

92 Uranium



.0505



.0500

.0505

.0490

.0475

.0488

,0481

.0478

.0486

.0490

.0485

.0488

.0488

.0490

.0493

.0493

.0492

.0496

.0488

.0490



.0740

.0743

.0755

.0743

.0728

.0752

.0746

.0750

.0762

.0778

.0798

.0858

.0865

.0903

.0917

.0925

.0944

.O% 1

.0964

.0992



Air



.0570

.0634

.0624

,0651

.a614



.0793

.0882

.0869

.OW6

,0854



Water

Nylon

Polyethylene

Polystyrene



.I486



.1457

.I517

.1431



2 5



7.4923

9.4481

10.110

1 1.493

12.287

13.207

13.621

14.743

14.536

15.620



.40



.80



1.50



2.50



4.00



6.00



26.879

32.893

34.886

38,467

40.150



8.5986



2123

2321



-2084



.2097

.1999



.3561

.3801

2921

2733

.2666



1.5759

1.6341

.9573

.7506

.7788



9.1109

9.4547

5.0960

3.7066

3.9958



40.027

42.061

22.460

16.155

17.358



154.59

166.08

89.240

64.330

69.209



534.90

291.00

211.31

277.40



706



T A B L E S 785-793.-FISSION



Artificial disintegration is generally considered in two parts : the first when

the bombarded atom suffers a change not greater than the loss (or gain) of an

alpha particle, and the second when the change in the bombarded atom is much

greater-the bombarded atom being at times split into two nearly equal parts.

This latter is called fission : the former, artificial disintegration. Fission was at

first brought about by bombardment with neutrons but it can be caused by

bombardment by almost any particle with the proper energy (see Table 726).

This effect can be produced in a number of isotopes of the heavier atoms such

as Np, U, Pa, Th, Pb, Sn, Eu, and Ni. Some other atoms such as Bi, Rb, TI,

Hg, Au, Pt, W, and many others show no fission; at least if such an effect

exists it is less than 1/1000 that of Th. There are a great many products of

fission as shown by a paper by scientists of the Plutonium

One

example of fission is

92U235

$- on1+ 4oZr97 52Te137

+ on1 + on1

There is a considerable release of energy when fission takes place. Complete

data are not available but such as are available give values of about 200 Mev

per fission per atom of the heavier elements. (See Table 790.) It is also to

be noted that there are two neutrons given as a result of the above reaction ;

thus, it is self-sustaining.



+



Journ. Amer. Chem. SOC.,vol. 68, p. 2411, 1946.



"O



T A B L E 785.-FISSION

Target substance



02u=6



Compound nucleus .................. ozU2"

Threshold energy for fast neutron fission, in Mev.. ....................

0

Energy released per fission, in Mev.. . 200

Energy of fission neutrons, in Mev.. . <3.5_

(Ave 1)

Average number of neutrons released

per fission .......................

2.3

(2 to 3.5)

Average number of neutrons released

1.4

per thermal neutron absorbed, q.. ..

For reference, see footnote 226,



I).



s&?

i:

s E'



-



o o ThZs2

mThm

u1Pa2p

s1Paw3

slPaw

.LJs2um



dJ=



5.402.22 Mev

1.10-f.05

-1



<6.9

-8

5.18-C.27

5.3 12.25




mPuz^p

e3Pu240



0



I

I



g.2



25



V



THRESHOLDS



*



-



c"l



*'



%

;



gz

22



V



n

n



P



d



s4Pu2'0



.oc



0

.

.



Threshold energy

exciting

forfission



5.08*.15 Mev

1.0 2 . 1



y



Y

Y



Estimated to be same as for w U ' ~



V



2



O C



Threshold energy

for

exciting fission



*



667.



T A B L E 786.-FISSION

V



DATA




<6.9

-8

5.31rt.27




%.z



V

2



;



Y



n

slow n



P



d

Y



slow n



slow n

~



Revised by J. L. Rhodes, University of Pennsylvania. For reference, see footnote 226, p. 667.



SMITHSONIAN PHYSICAL TABLES



u3



t e



M5



$2



707

T A B L E 787.-ESTIMATED

V A L U E S O F THE N E U T R O N B I N D I N G E N E R G Y

O F T H E DIVI'DING N U C L E U S *

Compound

nucleus



Neutron

binding energy



Neutron

binding energy



6.2 Mev

5.2

6.4

5.4

6.5

5.4

6.4



5.2 Mev

6.1

5.1

-6.3

-5.3

-5.4

-6.4



* For reference, see footnote 226,



p. 667.



T A B L E 788.-THE



C R I T I C A L E N E R G Y FOR F I S S I O N



*



The experimental values of the critical energy for fission of a number of isotopes have

been determined by Koch, McElhinney, and Gasteiger *" who give the following photo'fission threshold energies. (The work of Shoupp and Hill '" on the fast neutron fission

energies for Thza2and U" was used for the values given for ThW and UwO.)

Compound

nucleus



E.



wTh"2 . . 5.402.22 Mev

wThm .. 6.3

=Urn ... 5.18a.27



Compound

nucleus



Compound

nucleus



Ec



ozU235. . . 5.312.25 Mev

92uws . . . 5.082.15



muw0. . . 6.1



E.



MPum . . 5.312.27



MeV



Prepared by J. L. Rhodes, University of Pennsylvania.

Phys. Rev., vol. 77* p. 329, 1950.

Phys. Rev., voI. 75, p. 785, 1949.



211



242



T A B L E 789.-HALF-LIVES



F OR S P O N T A N E O U S F I S S I O N '"



These half-lives are calculated on the basis of a half-life of 10l6 years for Urn

Element



Z



Half-life



10l6years



, . . . . . 1.4X10"

. . . . . 7.62 loi3



.....

.....



6.8 x 10"

7.7x 1014



A



. . ...

MPurj0 .. . . .

W P u z m .. . ..

05AmU3 . . . .

osAmZ'l ' . . . .

MPU'"



Half-life



8.0x 10'' years

1.3X10"

1.6X1011

6.6x 10"

1.4X1010



Z'STurner, Rev. Mod. Phys., vol. 17, p. 292, 1945.



T A B L E 790.-THE



E N E R G Y R E L E A S E D B Y F I S SION O N D I V I S I O N O F SOME

ATOMS I N T O E Q U A L P A R T S *



Original



2WNia1

~OSn"'

eaEr'a'

aPbm

B2UZ3"



Two products



,,Si". 31

Mn", SU



-11 Mev

10

94



4,Nb103,104

4,,Pd11u,



For reference, see footnote 226, p. 667.



SMITHSONIAN PHYSICAL TABLES



Energy released

on division



120

200



Energy released

in subsequent

beta decay



2 Mev

12

13

32

31



708



T A B L E 791.-FISSION



PRODUCTS O F L O N G H A L F - L I F E



*



-u



E.5



z



,Ex uy

g5

'h



9



s6"



9.4 yr .74

19 d

1.82

55 d

1.5

25 y r

.65

62 h r 2.35

61 d

1.6

65 d

1.0

35 d

.15

90 hr I.T.

67 hr 1.5

41 d

.67

1.0 yr -.03

7.5 d 1.0

43 d

1.7

43 d

1.7

130 d

1.3

2.7 yr .7



'Revised by J.



?e



.-



E.5



::

2 2

b



z$-



...

Xu

25



-5



.92

.77



...



.75

.55



none

none



...



.5

.39

.6



E.5



-



.-;:



m"



2



z'



2"



.24

.00016

4.6



93 hr

90 d

32 d

77 hr

8 d

5.3 d

13 d

37 yr

12.8 d

30 d

275 d

13.8 d

11 d

3.7 yr

2 yr

15.4 d



1.2

I.T.



.-



...

5.9

6.4



...

...



6.2

3.7



.5



.018



.oms



.0008



...



x u

mc



.8



1.05

.6

.35

1.0

.90

.23

.2

2.4



m

$.



M

;

Gal



2:



v

C uf



x c

m

u



ClC



a'-



...



.72



...

...



I.T.



.28

687

.35

.28



0

.*



22



L



r:



ClC



1.08



2.

zg

E.9

.-



0

u



v uO

G



none



:>



$2



+3



3



none

none

none

none



.-.u



0



,033

.19

3.6

2.8

6



.22

.37



,085



1.2

.008

.75 -6

.53

6.1

.2

5.7

none

5.3

6

none

2.6

.58

2.6

none

.03

.084

.013

2.0



.02



L. Rhodes, University of Pennsylvania. For reference, see footnote 226, p. 667.



T A B L E 792.-CROSS



SECTIONS O F F I S S I O N A B L E N U C L E I FOR N E U T R O N S

(IN U N I T S OF

cm2) *

Cross section for energy ranges



Target

substance



szu=

MUrn



Ordinary uranium



Process



fission

scattering

fission

scattering

absorption

(resonance)

fission

scattering

absorption

(resonance)

fission

scattering

fission

scattering

absorption

fission

scattering

fission

scattering



Thermal



420+100



Resonance



Fast



30



2.4

6



t



.5



6

0



3 (ave)

17

3



.2 (ave)

17

5000



')assumed same as for wlUz"

0

0



17

8.3

0

17

0

17



6



.5



0



17



.1

6



0

17

0

17



3

6

.3



..



..



6



For reference, see footnote 226 p. 667.

t Most of the scattering of fast 'neutrons is inelastic scattering, resulting in large energy, losses (as

much as 90 percent).

$ T h e resonance peak for Urn occurs at approximately 5 ev and IS taken to

have an effective width of 0.16.



SMITHSONIAN PHYSICAL TABLES



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