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Radioactivity induced in ruthenium by neutrons
lPhysica IV, n o 11
D e c e m b e r I937
LETTER TO THE EDITOR Radioactivity induced in ruthenium by neutrons Natuurkundig Laboratorium der Rijks-Universiteit te Groningen S e v e r a l p e r i o d s h a v e b e e n o b t a i n e d in R u o n n e u t r o n a n d d e u t e r o n bomhardment. Kurtschatow, Nemenow and Selinow~) f o u n d t h e f o l l o w i n g p e r i o d s p r o d u c e d b y slow n e u t r o n s : 40 sec, 100 sec, 11 h, a n d 76 h, w i t h i n t e n s i t i e s h a v i n g t h e r a t i o of 100 : 100 : I0 : 40. Livingood2) o b s e r v e d p e r i o d s of 4 h , 3 9 h , 11 d a y s a n d 46 d a y s b y d e u t e r o n b o m b a r d m e n t . F r o m t h e f a c t t h a t t h e i n t e n s i t i e s of 40 sec a n d 100 sec w e r e i d e n t i c a l K u r t s c h a t o w concludes that there takes p l a c e a t w o s t e p r e a c t i o n als follows: R u T M (n, y) - + R u 105 (40 sec) --~ R h 105 (100 sec) - + P d 1~ T h i s c o n c l u s i o n c a n n o t b e r i g h t . C a l c u l a t i o n s h o w s t h a t t h e e l e m e n t s of a c h a i n reactioal w i t h 40 sec a n d 100 sec p e r i o d s m u s t h a v e e x t r a p o l a t e d i n t e n s i t i e s w h i c h are in t h e r a t i o of 1 : 5 a n d n o t 1 : 1. To clear u p t h i s m a t t e r we h a v e i r r a d i a t e d v e r y p u r e lZu ( f u r n i s h e d b y H e r a e u s ) w i t h n e u t r o n s of a P h i l i p s n e u t r o n g e n e r a t o r , h a v i n g a n i n t e n sity equivalent to a b o u t 2 g r a d i u m + beryllium. On b o m b a r d i n g with slow n e u t r o n s we f o u n d p e r i o d s of 45 sec, 4 min, 4 h a n d 22 h, t h e r e l a t i v e s a t u r a t i o n i n t e n s i t i e s b e i n g a b o u t 100, 10, B0 a n d 200. N o t r a c e of a n y l o n g e r p e r i o d c o u l d be o b s e r v e d . T h e p e r i o d s of 45 sec a n d 4 rain o b v i o u s l y m u s t be i d e n t i f i e d w i t h t h e well k n o w n R h p e r i o d s of 44 sec a n d 3.9 mill a n d are d u e t o a s m a l l c o n t a m i n a t i o n of o u r R u b y R h . S i n c e t h e s h o r t p e r i o d s of K u r t s c h a t o w (40 sec a n d 100 sec) are m u c h s t r o n g e r t h a n ours as c o m p a r e d w i t h t h e l o n g p e r i o d s , we c o n c l u d e t h a t t h e y t o o are t o be a t t r i b u t e d t o s o m e i m p u r i t y , m o s t p r o b a b l y R h . T h e i n v e s t i g a t i o n s are b e i n g c o n t i n u e d in o r d e r t o f i n d t h e p o s s i b l e c h a i n r e a c t i o n R u T M --~ R u ~~ --~ R h ~~ - + P d ~~ w h i c h c a n v e r y p r o b a b l y be c a u s e d b y slow n e u t r o n b o m b a r d m e n t . J. V E L D K A M P . H. D E V R I E S . Received December ll, 1937.
1) 2)
Kurtschatow, Nemenow and Selinow, C.R. :~01), 2162, 1935. Livirigood, Phys. Rev..~0, 425, 1936. - -
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D e c e m b e r I937
LETTER TO THE EDITOR Radioactivity induced in ruthenium by neutrons Natuurkundig Laboratorium der Rijks-Universiteit te Groningen S e v e r a l p e r i o d s h a v e b e e n o b t a i n e d in R u o n n e u t r o n a n d d e u t e r o n bomhardment. Kurtschatow, Nemenow and Selinow~) f o u n d t h e f o l l o w i n g p e r i o d s p r o d u c e d b y slow n e u t r o n s : 40 sec, 100 sec, 11 h, a n d 76 h, w i t h i n t e n s i t i e s h a v i n g t h e r a t i o of 100 : 100 : I0 : 40. Livingood2) o b s e r v e d p e r i o d s of 4 h , 3 9 h , 11 d a y s a n d 46 d a y s b y d e u t e r o n b o m b a r d m e n t . F r o m t h e f a c t t h a t t h e i n t e n s i t i e s of 40 sec a n d 100 sec w e r e i d e n t i c a l K u r t s c h a t o w concludes that there takes p l a c e a t w o s t e p r e a c t i o n als follows: R u T M (n, y) - + R u 105 (40 sec) --~ R h 105 (100 sec) - + P d 1~ T h i s c o n c l u s i o n c a n n o t b e r i g h t . C a l c u l a t i o n s h o w s t h a t t h e e l e m e n t s of a c h a i n reactioal w i t h 40 sec a n d 100 sec p e r i o d s m u s t h a v e e x t r a p o l a t e d i n t e n s i t i e s w h i c h are in t h e r a t i o of 1 : 5 a n d n o t 1 : 1. To clear u p t h i s m a t t e r we h a v e i r r a d i a t e d v e r y p u r e lZu ( f u r n i s h e d b y H e r a e u s ) w i t h n e u t r o n s of a P h i l i p s n e u t r o n g e n e r a t o r , h a v i n g a n i n t e n sity equivalent to a b o u t 2 g r a d i u m + beryllium. On b o m b a r d i n g with slow n e u t r o n s we f o u n d p e r i o d s of 45 sec, 4 min, 4 h a n d 22 h, t h e r e l a t i v e s a t u r a t i o n i n t e n s i t i e s b e i n g a b o u t 100, 10, B0 a n d 200. N o t r a c e of a n y l o n g e r p e r i o d c o u l d be o b s e r v e d . T h e p e r i o d s of 45 sec a n d 4 rain o b v i o u s l y m u s t be i d e n t i f i e d w i t h t h e well k n o w n R h p e r i o d s of 44 sec a n d 3.9 mill a n d are d u e t o a s m a l l c o n t a m i n a t i o n of o u r R u b y R h . S i n c e t h e s h o r t p e r i o d s of K u r t s c h a t o w (40 sec a n d 100 sec) are m u c h s t r o n g e r t h a n ours as c o m p a r e d w i t h t h e l o n g p e r i o d s , we c o n c l u d e t h a t t h e y t o o are t o be a t t r i b u t e d t o s o m e i m p u r i t y , m o s t p r o b a b l y R h . T h e i n v e s t i g a t i o n s are b e i n g c o n t i n u e d in o r d e r t o f i n d t h e p o s s i b l e c h a i n r e a c t i o n R u T M --~ R u ~~ --~ R h ~~ - + P d ~~ w h i c h c a n v e r y p r o b a b l y be c a u s e d b y slow n e u t r o n b o m b a r d m e n t . J. V E L D K A M P . H. D E V R I E S . Received December ll, 1937.
1) 2)
Kurtschatow, Nemenow and Selinow, C.R. :~01), 2162, 1935. Livirigood, Phys. Rev..~0, 425, 1936. - -
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