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A new activity 52 Ti
Volume25B. number 1
PHYSICS
LETTERS
14. L.Eisenbud. Thesis (1948) Princeton University. M. L.Goldberger and K.M.Watson. Collision theory (John Wiley and Sons. Inc. New York, 1964).
A NEW
24 July 1967
15. A. Dar, Nucl. Phys. 55 (1964) 305 and references therein. 16. R.J.Slobodrian, Nuovo Cimento 40 (1965) 443.
ACTIVITY
52Ti
H. MORINAGA, K. M1-YANO, K. F U J I K A W A , Department of Physics. University of Tokyo, Bunkyo-ku, Tokyo, Japan R. CHIBA, K. E B I S A W A , Department of Physics, Tokyo Institute of Technology, Ookayama, Megro-ku. Tokyo. Japan and N. KAWAI
Nippon Atomic Industry Group Co.. Kawasaki, Japan Received 6 June 1967
A new/3- activity is discovered with a half-life of 1.7 ± 0.1 min which is ascribed to 52Ti, formed through the 50Ti(t.p)52Ti reaction. Two T rays in coincidence, with E T = 125 and 17 keV, are observed. The fiend--point is 1.8 MeV. B e c a u s e of a l a c k of c o n v e n i e n t t r a c e r n u c l i d e s of t i t a n i u m t h e r e h a s b e e n s o m e i n t e r e s t in f i n d ing the p r e v i o u s l y unknown a c t i v i t y of 52Ti, which c o u l d be f o r m e d t h r o u g h the (t, p) r e a c t i o n on 50Ti, o r t h r o u g h a s p a l l a t i o n r e a c t i o n , and c o u l d h a v e a f a i r l y long l i f e t i m e . We h a v e d i s c o v e r e d an a c t i v i t y , which h a s , u n f o r t u n a t e l y , the u n e x p e c t e d l y s h o r t h a l f - l i f e of 1.7 m i n ; the s h o r t n e s s , h o w e v e r , is i n t e r e s t i n g f r o m a n u c l e a r - s t r u c t u r e point of v i e w . T h i s s e a r c h w a s m o t i v a t e d by the r e c e n t d i s c o v e r y of a v e r y l o w - l y i n g 1 + s t a t e in 52V, the d a u g h t e r n u c l i d e [1]. T h e 1 + s t a t e is not one of the l o w e s t c o n f i g u r a t i o n s . T h i s s t a t e was m i s s e d in p r e v i o u s s t u d i e s of 52V t h r o u g h the 51V(d, p) r e a c t i o n [2]. We h a v e b o m b a r d e d both m e t a l l i c s a m p l e s of n a t u r a l t i t a n i u m and o x i d e s a m p l e s of e n r i c h e d 50Ti with a 3 MeV t r i t o n b e a m f r o m the e l e c t r o s t a t i c a c c e l e r a t o r of the Nippon A t o m i c I n d u s t r y G r o u p Co. T h e a c t i v i t y was sought by t r a c i n g the p o s s i b l e 125 keV and 17 keV T r a y s w h i c h should d e - e x c i t e the 1 + s t a t e . F i v e d o m i n a n t p e a k s w e r e s e e n at e n e r g i e s of 125, 141, 320, 511 and 1434 keV. F i g . 1 s h o w s the y - r a y s p e c t r u m a r o u n d the e n e r g y of 125 keV, t a k e n with a 2 c m 3 Ge(Li) d e t e c t o r . T h e 125 keV 22
d e c a y e d with a h a l f - l i f e of 1.7 m i n . T h e 141 keV p e a k d e c a y e d with a h a l f - l i f e s h o r t e r than 1 m i n . T h i s p e a k can p o s s i b l y be a s s i g n e d to the 20 s i s o m e r of 46Sc, the p r o d u c t of 47Ti (t, a ) . T h e 320 and 1 434 keV p e a k s w e r e a s s i g n e d to 51Ti and 52V, r e s p e c t i v e l y . F i g . 2 s h o w s the d e c a y c u r v e of the 125 keV peak. T h e h a l f - l i f e of 52Ti was d e t e r m i n e d a s 1.7 ± 0.1 m i n . A l o w - e n e r g y T - r a y s p e c t r u m was taken with a thin NaI c r y s t a l with a b e r y l l i u m window. A p e a k at an e n e r g y of 17 keV was o b s e r v e d . T h i s p e a k d e c a y e d with a s i m i l a r h a l f - l i f e as the 125 keV peak. T h e fl s p e c t r u m was o b s e r v e d with an a n t h r a c e n e c r y s t a l which was g a t e d with the 125 keV V r a y . An e n d - p o i n t e n e r g y w a s found of 1.8 MeV which w a s in good a g r e e m e n t with the e x p e c t e d v a l u e a s c o m p u t e d f r o m the g r o u n d - s t a t e Q v a l u e of the 5 0 T i ( t , p ) r e a c t i o n [3]. T h e 17 keV l i n e was c o i n c i d e n t with the 125 keV l i n e (as d e t e r m i n e d with a s l o w c o i n c i d e n c e s y s t e m , 2~-= 0.9 s). No o t h e r a p p r e c i a b l e T r a y s with about 1.7 m i n h a l f - l i f e w e r e o b s e r v e d . T h e l o g f t v a l u e of the 1.8 MeV b e t a t r a n s i t i o n is e s t i m a t e d to be 4.0. T h i s l o g f t v a l u e is s u r p r i s ingly low in v i e w of the p o s s i b l e c o n f i g u r a t i o n s f o r the p a r e n t and d a u g h t e r n u c l i d e s . T h e p r i m a r y
Volume25B. number 1
PHYSICS
I0'L
LETTERS
24 July 1967
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Fig. 1. G a m m a - r a y s p e c t r a taken with a 2 cm 3 Oe(Li) detector at 22 s ( s m a l l e r dots), at 170 s (triangles). and at 695 s ( l a r g e r dots) a f t e r the end of a 90 s bomb a r d m e n t of a m e t a l l i c natural titanium target. c o n f i g u r a t i o n w o u l d b e [f½(p)]2 [ p , ( n ) ] 2 f o r t h e g r o u n d - s t a t e of 52Ti a n d L~_~[fz(P)]~P~(n) f o r t h e 1 + s t a t e of 52V, a n d t h u s t h e / 3 : - d e d a ~ / w o u l d b e f i r s t forbidden. The allowed transition can occur bet w e e n [f~(p)]2 p~(p) p~(n) f o r t h e 1 + s t a t e in 52V a n d [f~(p)]2 [p~(~)]2 f o r t h e g r o u n d s t a t e of 5 2 T i , o r bet~veen [f~(p)]3 f_~(n) a n d [f~(p)]2 [f~(n)]2. T h e r e a r e m a n y o~h~r s e c o n d a r y c o n f i g u r a t i o n s f o r t h e b e t a d e c a y . T h e f a c t t h a t l o g f t = 4.0, w h i c h i s a l m o s t t h e l o w e s t o b s e r v e d v a l u e in t h i s r e g i o n , s u g g e s t s t h a t t h e r e i s a k i n d of s i m i l a r i ty b e t w e e n t h e 0 + g r o u n d s t a t e of 52Ti a n d t h e 1 + s t a t e in 52V, a n d t h e r e w o u l d b e a c o n s t r u c t i v e p h a s e r e l a t i o n a m o n g v a r i o u s b e t a a m p l i t u d e s in these secondary configurations. This presumpt i o n , t o g e t h e r w i t h t h e f a c t t h a t t h e 1+ s t a t e a p -
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15 (MIN)
Fig. 2. Decay curve of the 125 keV ~ ray. p e a r s to low, s e e m s t o l e a d u s to t h e c o n c l u s i o n t h a t t h e 1+ s t a t e h a s a v e r y s p e c i a l p r o p e r t y l i k e t h e g r o u n d s t a t e of t h e e v e n - e v e n n u c l e u s . We have already encountered a similar situat i o n in t h e c a s e of t h e d e c a y of 5 0 C a [4].
References 1. P , V a n Assche, U . G r u b e r , B . P . M a i e r , H.R.Koch and W.B.Schult, Nucl. Phys. 79 (1966) 565; P. Carlos, R. Samama and A.Audias, Nucl. Phys. A93 (1967) 631. 2. J.H. B j e r r e g a a r d , P. F. Dahl, O. Hansen and G . S i denius, Nucl. Fhys. 51 (1964) 641. J. Catal~, A. Garcfa, J. M. Bolta, S. Hinds, H. M a r chant and A. E. F o r e s t , Nucl. Phys. 74 (1965) 1. 3. D. Williams, J. Knight and W. Leland, Phys. L e t t e r s 22 (1966) 162. 4. Y. Shida, M. Ishihara, K. Miyano, H. Morinaga and R.Chiba, Phys. L e t t e r s 13 (1964) 59.
23
PHYSICS
LETTERS
14. L.Eisenbud. Thesis (1948) Princeton University. M. L.Goldberger and K.M.Watson. Collision theory (John Wiley and Sons. Inc. New York, 1964).
A NEW
24 July 1967
15. A. Dar, Nucl. Phys. 55 (1964) 305 and references therein. 16. R.J.Slobodrian, Nuovo Cimento 40 (1965) 443.
ACTIVITY
52Ti
H. MORINAGA, K. M1-YANO, K. F U J I K A W A , Department of Physics. University of Tokyo, Bunkyo-ku, Tokyo, Japan R. CHIBA, K. E B I S A W A , Department of Physics, Tokyo Institute of Technology, Ookayama, Megro-ku. Tokyo. Japan and N. KAWAI
Nippon Atomic Industry Group Co.. Kawasaki, Japan Received 6 June 1967
A new/3- activity is discovered with a half-life of 1.7 ± 0.1 min which is ascribed to 52Ti, formed through the 50Ti(t.p)52Ti reaction. Two T rays in coincidence, with E T = 125 and 17 keV, are observed. The fiend--point is 1.8 MeV. B e c a u s e of a l a c k of c o n v e n i e n t t r a c e r n u c l i d e s of t i t a n i u m t h e r e h a s b e e n s o m e i n t e r e s t in f i n d ing the p r e v i o u s l y unknown a c t i v i t y of 52Ti, which c o u l d be f o r m e d t h r o u g h the (t, p) r e a c t i o n on 50Ti, o r t h r o u g h a s p a l l a t i o n r e a c t i o n , and c o u l d h a v e a f a i r l y long l i f e t i m e . We h a v e d i s c o v e r e d an a c t i v i t y , which h a s , u n f o r t u n a t e l y , the u n e x p e c t e d l y s h o r t h a l f - l i f e of 1.7 m i n ; the s h o r t n e s s , h o w e v e r , is i n t e r e s t i n g f r o m a n u c l e a r - s t r u c t u r e point of v i e w . T h i s s e a r c h w a s m o t i v a t e d by the r e c e n t d i s c o v e r y of a v e r y l o w - l y i n g 1 + s t a t e in 52V, the d a u g h t e r n u c l i d e [1]. T h e 1 + s t a t e is not one of the l o w e s t c o n f i g u r a t i o n s . T h i s s t a t e was m i s s e d in p r e v i o u s s t u d i e s of 52V t h r o u g h the 51V(d, p) r e a c t i o n [2]. We h a v e b o m b a r d e d both m e t a l l i c s a m p l e s of n a t u r a l t i t a n i u m and o x i d e s a m p l e s of e n r i c h e d 50Ti with a 3 MeV t r i t o n b e a m f r o m the e l e c t r o s t a t i c a c c e l e r a t o r of the Nippon A t o m i c I n d u s t r y G r o u p Co. T h e a c t i v i t y was sought by t r a c i n g the p o s s i b l e 125 keV and 17 keV T r a y s w h i c h should d e - e x c i t e the 1 + s t a t e . F i v e d o m i n a n t p e a k s w e r e s e e n at e n e r g i e s of 125, 141, 320, 511 and 1434 keV. F i g . 1 s h o w s the y - r a y s p e c t r u m a r o u n d the e n e r g y of 125 keV, t a k e n with a 2 c m 3 Ge(Li) d e t e c t o r . T h e 125 keV 22
d e c a y e d with a h a l f - l i f e of 1.7 m i n . T h e 141 keV p e a k d e c a y e d with a h a l f - l i f e s h o r t e r than 1 m i n . T h i s p e a k can p o s s i b l y be a s s i g n e d to the 20 s i s o m e r of 46Sc, the p r o d u c t of 47Ti (t, a ) . T h e 320 and 1 434 keV p e a k s w e r e a s s i g n e d to 51Ti and 52V, r e s p e c t i v e l y . F i g . 2 s h o w s the d e c a y c u r v e of the 125 keV peak. T h e h a l f - l i f e of 52Ti was d e t e r m i n e d a s 1.7 ± 0.1 m i n . A l o w - e n e r g y T - r a y s p e c t r u m was taken with a thin NaI c r y s t a l with a b e r y l l i u m window. A p e a k at an e n e r g y of 17 keV was o b s e r v e d . T h i s p e a k d e c a y e d with a s i m i l a r h a l f - l i f e as the 125 keV peak. T h e fl s p e c t r u m was o b s e r v e d with an a n t h r a c e n e c r y s t a l which was g a t e d with the 125 keV V r a y . An e n d - p o i n t e n e r g y w a s found of 1.8 MeV which w a s in good a g r e e m e n t with the e x p e c t e d v a l u e a s c o m p u t e d f r o m the g r o u n d - s t a t e Q v a l u e of the 5 0 T i ( t , p ) r e a c t i o n [3]. T h e 17 keV l i n e was c o i n c i d e n t with the 125 keV l i n e (as d e t e r m i n e d with a s l o w c o i n c i d e n c e s y s t e m , 2~-= 0.9 s). No o t h e r a p p r e c i a b l e T r a y s with about 1.7 m i n h a l f - l i f e w e r e o b s e r v e d . T h e l o g f t v a l u e of the 1.8 MeV b e t a t r a n s i t i o n is e s t i m a t e d to be 4.0. T h i s l o g f t v a l u e is s u r p r i s ingly low in v i e w of the p o s s i b l e c o n f i g u r a t i o n s f o r the p a r e n t and d a u g h t e r n u c l i d e s . T h e p r i m a r y
Volume25B. number 1
PHYSICS
I0'L
LETTERS
24 July 1967
125;0V
/
~
141keV
W I--
~10 Z
F-Z ~)
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50
I00 CHANNEL
Io
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150 NUMBER
Fig. 1. G a m m a - r a y s p e c t r a taken with a 2 cm 3 Oe(Li) detector at 22 s ( s m a l l e r dots), at 170 s (triangles). and at 695 s ( l a r g e r dots) a f t e r the end of a 90 s bomb a r d m e n t of a m e t a l l i c natural titanium target. c o n f i g u r a t i o n w o u l d b e [f½(p)]2 [ p , ( n ) ] 2 f o r t h e g r o u n d - s t a t e of 52Ti a n d L~_~[fz(P)]~P~(n) f o r t h e 1 + s t a t e of 52V, a n d t h u s t h e / 3 : - d e d a ~ / w o u l d b e f i r s t forbidden. The allowed transition can occur bet w e e n [f~(p)]2 p~(p) p~(n) f o r t h e 1 + s t a t e in 52V a n d [f~(p)]2 [p~(~)]2 f o r t h e g r o u n d s t a t e of 5 2 T i , o r bet~veen [f~(p)]3 f_~(n) a n d [f~(p)]2 [f~(n)]2. T h e r e a r e m a n y o~h~r s e c o n d a r y c o n f i g u r a t i o n s f o r t h e b e t a d e c a y . T h e f a c t t h a t l o g f t = 4.0, w h i c h i s a l m o s t t h e l o w e s t o b s e r v e d v a l u e in t h i s r e g i o n , s u g g e s t s t h a t t h e r e i s a k i n d of s i m i l a r i ty b e t w e e n t h e 0 + g r o u n d s t a t e of 52Ti a n d t h e 1 + s t a t e in 52V, a n d t h e r e w o u l d b e a c o n s t r u c t i v e p h a s e r e l a t i o n a m o n g v a r i o u s b e t a a m p l i t u d e s in these secondary configurations. This presumpt i o n , t o g e t h e r w i t h t h e f a c t t h a t t h e 1+ s t a t e a p -
I0 0
I
I
5
I0 TIME
'
%
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15 (MIN)
Fig. 2. Decay curve of the 125 keV ~ ray. p e a r s to low, s e e m s t o l e a d u s to t h e c o n c l u s i o n t h a t t h e 1+ s t a t e h a s a v e r y s p e c i a l p r o p e r t y l i k e t h e g r o u n d s t a t e of t h e e v e n - e v e n n u c l e u s . We have already encountered a similar situat i o n in t h e c a s e of t h e d e c a y of 5 0 C a [4].
References 1. P , V a n Assche, U . G r u b e r , B . P . M a i e r , H.R.Koch and W.B.Schult, Nucl. Phys. 79 (1966) 565; P. Carlos, R. Samama and A.Audias, Nucl. Phys. A93 (1967) 631. 2. J.H. B j e r r e g a a r d , P. F. Dahl, O. Hansen and G . S i denius, Nucl. Fhys. 51 (1964) 641. J. Catal~, A. Garcfa, J. M. Bolta, S. Hinds, H. M a r chant and A. E. F o r e s t , Nucl. Phys. 74 (1965) 1. 3. D. Williams, J. Knight and W. Leland, Phys. L e t t e r s 22 (1966) 162. 4. Y. Shida, M. Ishihara, K. Miyano, H. Morinaga and R.Chiba, Phys. L e t t e r s 13 (1964) 59.
23