R e p o r t e r :

G i l l i a n M a e L .

R e s u l l a r

I V – B o h r

Topic Outline* D e f i n i t i

o n (Wh a t

i s

T r a n s m u t

a t i o n )

* H i s t o r y

* A l c h e m y

* M o d e r n

T r a n s m u

t a t i o n

* T y p e s

* H o w d o e s

i t w o r k ?

(T r a n s m u t

a t i o n )

* T r a n s m u t

a t i o n i n

t h e

U n i v e r s e

What the FACT?!Transmutation

* N u c l e a r

T r a n s mu t a t i o n : (n o u n )

t h e c o n v e r s i o n o f

o n e e l e m e n t o r

n u c l i d e i n t o

a n o t h e r e i t h e r

n a t u r a l l y o r

a r t i f i c i a l l y .

* A n u c l e a r r e a c t i o n

(i n w h i c h a n o u t s i d e

p a r t i c l e r e a c t s

History: Alchemy -> Transmutation (Timeline)

* The term t r a n s m u t a t i o n dates

back to a l c h e m y .

* P h i l o s o p h e r ’s S t o n e ->

c h r y s o p o e i a (t h e transformation

of base metals i n t o g o l d ).

* F a l s e a s s u m p t i o n s o f

t u r n i n g b a s i c m e t a l s

i n t o g o l d .

History: Alchemy -> Transmutation (Timeline)

* B y t h e 1720s , t h e r e w e r e

n o l o n g e r a n y

r e s p e c t a b l e f i g u r e s

p u r s u i n g t h e p h y s i c a l

t r a n s m u t a t i o n o f

s u b s t a n c e s i n t o g o l d .

* A n t o i n e L a v o i s i e r :

* 18t h c e n t u r y

* r e p l a c e d the alchemical theory of

elements w i t h t h e m o d e r nt h e o r y o f c h e m i c a l

e l e m e n t s .

History: Alchemy -> Transmutation (Timeline)

* F r e d e r i c k S o d d y +

E r n e s t R u t h e r f o r d

* 1901

* D i s c o v e r e d t h a t

r a d i o a c t i v e

t h o r i u m was converting itself

into radium i n 1901

* D i s c o v e r y o f

n u c l e a r f i s s i o n a n d

f u s i o n

* (20t h c e n t u r y )

Artificial Transmutation

* M a y o c c u r i n

m a c h i n e r y t h a t h a s

e n o u g h e n e r g y t o

c a u s e c h a n g e s i n t h e

n u c l e a r s t r u c t u r e

o f t h e e l e m e n t s .

* M a c h i n e s t h a t c a n

c a u s e a r t i f i c i a l

t r a n s m u t a t i o n

i n c l u d e p a r t i c l e

a c c e l e r a t o r s

Artificial Transmutation

* Conventional fission power reactors also

cause artificial transmutation, not from the

power of the machine, but by exposing

elements to neutrons produced by a fission

from an artificially

produced n u c l e a r c h a i nr e a c t i o n .

* A r t i f i c i a l n u c l e a r

t r a n s m u t a t i o n h a s

b e e n c o n s i d e r e d a s a

p o s s i b l e m e c h a n i s m

f o r r e d u c i n g t h e

Natural Transmutation

* R e s p o n s i b l e f o r t h e

c r e a t i o n o f a l l t h e

c h e m i c a l e l e m e n t s

w e o b s e r v e

n a t u r a l l y .

* One type of natural transmutation

observable in the present occurs when

certain radioactive elements p r e s e n ti n n a t u r e

s p o n t a n e o u s l y d e c a y

b y a p r o c e s s t h a t

How?* N a t u r a l , o r

s p o n t a n e o u s , t r a n s m u

t a t i o n o c c u r s i n

u n s t a b l e , r a d i o a c t i v

e e l e m e n t s , w h i c h

d e c a y i n t o a s e r i e s

o f o t h e r e l e m e n t s

u n t i l a s t a b l e

e l e m e n t i s f o r m e d .

* A r t i f i c i a l , o r

i n d u c e d , t r a n s m u t a t i

o n o c c u r s w h e n a t o m s

How?

* M o s t n u c l e a r

r e a c t i o n s i n v o l v e

a r t i f i c i a l l y

t r a n s m u t i n g

e l e m e n t s , a l t h o u g h

s u c h r e a c t i o n s a r e

u s u a l l y r e f e r r e d t o

b y t e r m s d e n o t i n g

t h e s p e c i f i c n a t u r e

o f t h e p r o c e s s

(f i s s i o n , f u s i o n , i r r

How?

* P a r t i c l e a c c e l e r a t o r s

m a y b e u s e d t o b o m b a r d

e l e m e n t s w i t h a l p h a

p a r t i c l e s (t w o p r o t o n s

a n d t w o

n e u t r o n s ), d e u t e r o n s

(o n e p r o t o n a n d o n e

n e u t r o n ), o r n u c l e i o f

a t o m s o f e l e m e n t s s u c h

a s c a r b o n o r b o r o n . I n

t h e s e c a s e s , s o m e o r a l l

o f t h e p r o t o n s i n t h e

b o m b a r d i n g p a r t i c l e s

How?

* I n a n u c l e a r

r e a c t o r , t h e t a r g e t

n u c l e u s i s

b o m b a r d e d w i t h

n e u t r o n s , c a u s i n g

t h e n u c l e i t o

f i s s i o n (s p l i t ) o r

m e r e l y t o b e c o m e

r a d i o a c t i v e . (T h e

r a d i o a c t i v e n u c l e i

t h e n t r a n s m u t e

Transmutation in the Universe

* T h e B i g B a n g =

t h o u g h t to the be the origin of

the hydrogen (including

all d e u t e r i u m ) a n dh e l i u m i n t h e

u n i v e r s e .

* T h e Big Bang also produced small

amounts of lithium, beryllium and

perhaps b o r o n . M o r el i t h i u m , b e r y l l i u m

a n d b o r o n w e r e

Transmutation in the Universe

* The Solar System i s t h o u g h t t oh a v e c o n d e n s e d

a p p r o x i m a t e l y 4.6

b i l l i o n y e a r s b e f o r e

t h e p r e s e n t , f r o m a

c l o u d o f h y d r o g e n a n d

h e l i u m c o n t a i n i n g

h e a v i e r e l e m e n t s i n

d u s t g r a i n s f o r m e d

p r e v i o u s l y b y a l a r g e

n u m b e r o f s u c h s t a r s .

Transmutation in the Universe

* Most natural transmutation on the Earth today

is mediated by c o s m i c r a y s

a n d by the radioactive decay of

radioactive primordial nuclides l e f to v e r f r o m t h e i n i t i a l

f o r m a t i o n o f t h e

s o l a r s y s t e m (s u c h a s

p o t a s s i u m -40, u r a n i u m

a n d t h o r i u m ), p l u s t h e

r a d i o a c t i v e d e c a y o f

p r o d u c t s o f t h e s e

n u c l i d e s