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Internal magnetic field of iodine in iron
Volume 20, number 1
PHYSICS
INTERNAL
MAGNETIC
LETTERS
FIELD
15 January 1966
OF
IODINE
IN
IRON
H. D E W A A R D and S. A. D R E N T J E
Natuurkundig Laboratorium, University of Groningen, The Netherlands R e c e i v e d 13 D e c e m b e r 1965
Large hyperfine fields a t nuclei of non-magnetic atoms in ferro-magnetic host lattices have been reported and discussed for a number of cases [1-5]. In particular, Frankel et al. [3] have studied the behaviour of hyperfine fields versus atomic number for nuclei ranging from Ru (Z =44) to Te (Z = 52), dissolved in iron and nickel. They have found a smooth variation of the field, with a change of sign near tin (Z = 50). A part of their results for solutions in iron is shown again in fig. i, with the addition of the value for iodine reported in this letter. The hyperfine field for iodine is derived from
a measurement of the Zeeman splitting of the 27.7 keV gamma transition of 129I dissolved in iron. This transition is excited in the decay of 33 day 129Te m, which activity was obtained by irradiating an enriched 128Te sample for one month at a neutron flux of 2 × 1014 cm-2s -I. Because of the rather low specific activity (about 0.2 mCi/mg) and the high chemical reactivity of tellurium with iron it was not attempted to dissolve the activity by normal means such as diffusion or making an alloy. It is believed that
Te 129 m in Fe HOST
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F i g . 1. H y p e r f i n e f i e l d s a t n o n - m a g n e t i c n u c l e i i n a n i r o n h o s t , v e r s u s a t o m i c n u m b e r . T h e s i g n of t h e f i e l d f o r C d , I n a n d I w h i c h h a s not been m e a s u r e d directly, is derived from the general trend. The data are from r e f . 3, e x c e p t f o r t h e i o d i n e p o i n t , w h i c h i s f r o m t h e present work.
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Fig. 2. M ~ s s b a u e r absorption s p e c t r a for two different v e l o c i t y r a n g e s obtained with a s o u r c e of 129Te m in iron and a K129I a b s o r b e r , both at about 100OK.
,:
Volume 20, number 1
PHYSICS
LETTERS
15 January 1966
t
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VELOCITY (rnm /sec)
Fig. 3. Calculated absorption s p e c t r u m of 129I in a field of 106 Oe. P a r a m e t e r s used; magnetic moments
[9]: ~ = 2.617 n.m. (ground state), ~* = 2.84 n.m. (excited state), half-width of one component = 1.15mm/s (experimental value obtained with Zn129Te source and K129I absorber), source transversely magnetized. t h e s e p r o c e s s e s lead to the f o r m a t i o n of p a r a m a g n e t i c m i c r o c r y s t a l s of i r o n t e l l u r i d e s d i s p e r s e d in the iron. To avoid this as much as p o s s i b l e , the S c a n d i n a v i a n type isotope s e p a r a t o r of our Institute was u s e d to produce a s e p a r a t e d b e a m of 50 keV 129Te m ions that were shot into a 12 # thick foil of v e r y p u r e i r o n with a c a r e f u l ly c l e a n e d and etched s u r f a c e . In this way, s o u r ces of about 100 p C i w e r e obtained f r o m s e p a r a t o r r u n s l a s t i n g for about 8 hours. M b s s b a u e r s p e c t r a of such s o u r c e s were taken at a t e m p e r a t u r e of about 100OK, u s i n g a K129I single line a b s o r b e r , in a s i m p l e s t y r o f o a m c r y o s t a t v e r y s i m i l a r to one d e s c r i b e d e a r l i e r [6]. The s p e c t r o m e t e r was of the Kankeleit [7] type. Two s p e c t r a for different velocity r a n g e s a r e shown in fig. 2. The s p e c t r u m is i n t e r p r e t e d in the following way: (1) The c e n t r a l p a r t (a) r e s u l t s f r o m Te a t o m s in n o n - m a g n e t i c or weakly m a g n e t i c s u r r o u n d i n g s . T h i s p a r t shows an i n c o m p l e t e l y r e s o l v e d quadrupole s t r u c t u r e , r e s e m b l i n g that found for i r o n - t e l l u r i d e s (to be r e p o r t e d elsewhere). D e s pite the m a s s s e p a r a t i o n , the amount of 128Te in the 129Te m m a y s t i l l be high enough to cause a p a r t i a l f o r m a t i o n of t e l l u r i d e s or n o n - m a g n e t i c c l u s t e r s of Te a t o m s . A rough e s t i m a t e , b a s e d on s e p a r a t o r r e s o l u t i o n and gas p r e s s u r e n e a r the ion s o u r c e , i n d i c a t e s that a few # g / c m 2 of 128Te m a y have been deposited at the 129Tern position. Combined with data on the d i s t r i b u t i o n of the Te a t o m s in the host, d e r i v e d f r o m the t a b l e s of Domey [8], we conclude that the Te c o n c e n t r a t i o n in the m a x i m u m of the d i s t r i b u t i o n
is a few atom p e r c e n t for our b e s t s o u r c e . P a r t of this can f o r m i r o n t e l l u r i d e s or t e l l u r i u m c l u s t e r s . T h i s i n t e r p r e t a t i o n is c o n f i r m e d by the o b s e r v a t i o n that another s o u r c e , made with a lower r e s o l u t i o n of the m a s s s e p a r a t o r y i e l d s a s p e c t r u m with a f r a c t i o n a l i n t e n s i t y of the c e n t r a l p a r t (a) of the s p e c t r u m l a r g e r by a f a c t o r of about 2. The ease with which nonf e r r o m a g n e t i c i r o n - t e l l u r i u m compounds a r e f o r m e d is f u r t h e r d e m o n s t r a t e d by the fact that a f t e r heating this s o u r c e for 15 m i n to 700°C, the outer l i n e s b, c, d and e of the s p e c t r u m , to be d i s c u s s e d next, have c o m p l e t e l y d i s a p peared. (2) The two c l e a r l i n e s b and c and the two b r o a d e n e d weak l i n e s d and e r e p r e s e n t p a r t of the s p e c t r u m expected for 129I n u c l e i in a strong magnetic hyperfine field (Hint). The t e l l u r i u m a t o m s giving r i s e to this p a r t p r e s u m a b l y r e place i r o n a t o m s in the i r o n lattice. F o r c o m p a r i s o n , the c a l c u l a t e d hyperfine s p e c t r u m of the 27.7 keV t r a n s i t i o n in 129I for a field Hint = 106 Oe is shown in fig. 3. In view of the l a r g e c o n t r i b u t i o n of the c e n t r a l p a r t of the s p e c t r u m and the low i n t e n s i t y of l i n e s d and e, no l e a s t s q u a r e s fit of the c a l c u l a t e d s p e c t r u m to the m e a s u r e d points was attempted. Instead, Hint was d e t e r m i n e d f r o m the d i s t a n c e Abc of l i n e s b and c, which c o r r e s p o n d s to 0.14 ~Hin tThe a v e r a g e of t h r e e m e a s u r e m e n t s yields Hint = (1.13+0.04) x 106 Oe. This r e s u l t p r o v i d e s a smooth continuation of the t r e n d o b s e r v e d by F r a n k e l et al. [3]. A p p a r ently the effect on the field of adding e l e c t r o n s in 39
Volume 20, number 1
PHYSICS
the 5(sp) s h e l l i n c r e a s e s a s we a p p r o a c h the c l o s e d s h e l l e l e c t r o n c o n f i g u r a t i o n of xenon. A r e l e v a n t i t e m in t h i s r e s p e c t i s t h e p o s i t i v e e n e r g y s h i f t of 0.34 m m / s of the h y p e r f i n e p a t t e r n w i t h r e s p e c t to the K129I a b s o r b e r . F r o m a c o m p a r i s o n with o t h e r d a t a on the i s o m e r i c s h i f t s in 129I c o m p o u n d s [6] we l e a r n t h a t t h i s s h i f t c o r r e s p o n d s to an e f f e c t i v e n e g a t i v e c h a r g e of about - 0 . 7 5 e on t h e i o d i n e , a s s u m i n g t h a t t h e r e is no sp h y b r i d i z a t i o n . T h u s , t h e e l e c t r o n c o n f i g u r a t i o n of t h e I ion would b e t h a t of x e n o n w i t h ¼ of a p e l e c t r o n m i s s i n g . T h e i o n i c r a d i u s of s u c h an ion is about 2 ,~ and it w i l l h a r d l y f i t in the l a t t i c e . T h e r e w i l l be c o n s i d e r a b l e o v e r l a p of the 5s and 5p e l e c t r o n w a v e f u n c t i o n s w i t h t h o s e of the 3d e l e c t r o n s of t h e i r o n , l e a d i n g to a p o l a r i z a t i o n of e l e c t r o n s in the n = 5 s h e l l . T h e h y p e r f i n e f i e l d m a y be p a r t l y due to a d i r e c t c o n t a c t i n t e r a c t i o n of t h e p o l a r i z e d 5s e l e c t r o n s w i t h t h e n u c l e u s , p a r t l y to p o l a r i z a t i o n i n d u c e d in the c o r e by t h e n = 5 e l e c t r o n s . T h e f i r s t c o n t r i b u t i o n is p r o b a b l y p r e d o m i n a n t , but a u n i q u e i n t e r p r e t a t i o n a p p e a r s to b e i m p o s s i b l e at t h e m o m e n t , b e c a u s e q u a n t i t a t i v e c a l c u l a t i o n s of t h e v a r i o u s p o s s i b l e c o n t r i b u t i o n s a r e l a c k i n g [2, 5]. We s h o u l d l i k e to p o i n t out t h a t t h e s o - c a l l e d M o r i t a e x p e r i m e n t [10] on n o n - c o n s e r v a t i o n of p a r i t y s h o u l d be f e a s i b l e w i t h s o u r c e s of 129Tern in F e l i k e the o n e s d e s c r i b e d , p r o v i d e d the i n t e n s i t y of t h e a b s o r p t i o n l i n e s b and c c o u l d be in-
THE
Q VALUES
OF
THE
REACTION
LETTERS
15 January 1966
c r e a s e d to a f e w p e r c e n t , e.g. by u s i n g a l o w e r t e m p e r a t u r e and a s t i l l b e t t e r s o u r c e . We w i s h to t h a n k D r . R. M. H o u s l e y f o r h i s i n t e r e s t in t h i s w o r k and f o r u s e f u l s u g g e s t i o n s . T h i s i n v e s t i g a t i o n w a s m a d e p o s s i b l e by f i n a n c i a l support from the Foundation for Fundamental R e s e a r c h on M a t t e r (F. O. M.) s u b s i d i z e d by the Netherlands Organization for Pure Scientific R e s e a r c h (Z. W. O.). 1. p . N . Samoilov, V.V. Sklyarevskii and E. P. Sepanov, Zh. Experim. i Teor. Fiz. 36 (1959) 1944; 38 (1960) 359. 2. D.A. Shirley and G. A. Westenbarger, Phys. Rev. 138 (1965) A170. 3. R.B. Frankel, J. Huntzicker, E. Matthias, S.S. Rosenblum and D. A. Shirley, Physics Letters 15 (1965) 163. 4. M. Kontani, K. Asayama and J.Itoh, J. Phys. Soc. Japan 20 (1965) 1737. 5. A . J . F r e e m a n and R.E.Watson, in Magnetism, Ed. G. T. Rado and H. Suhl (Academic P r e s s , 1965} Vol. IIA, p.274. 6. D.W. Hafemeister, G. DePasquali and H. De Waard, Phys. Rev. 135 (1964) B1089. 7. E. Kankeleit, Rev. Sci. Instr. 35 (1964) 194. 8. B. Domey, Proc. fourth Scandinavian isotope separator symposium (Nobel Institute, Stockholm, 1963) nr. 4. 9. H. De Waard and J. Heberle, Phys. Rev. 136 (1964) B1615. 10. M.Morita, Phys. Rev. 122 (1961) 1525.
9Be(p,d)8Be
AND
8Be
~
2 4He
W. R E I C H A R T , H . H . S T A U B , H. STUSSI and F. Z A M B O N I Physik-Institut der Universit~tt Zi~rich
Received 15 December 1965
The following Q values have been measured absolutely- Q1 = 559.0 ± 1.1 keV for 9Be(p, d)SBe , Q2 92.6 * 0.8 keV for 8Be(C0 ~.
T h e f a i l u r e to f i n d a r e s o n a n c e in t h e e l a s t i c s c a t t e r i n g of a p a r t i c l e s on h e l i u m n e a r t h e a p a r t i c l e energT_ c o r r e s p o n d i n g to t h e a c c e p t e d Q v a l u e of t h e 8Be ~ 2~ r e a c t i o n , 94.7 + 0.6 k e V [1], p r o m p t e d t h e p r e s e n t r e d e t e r m i n a t i o n of t h e Q v a l u e s of the r e a c t i o n s 9Be + 1H - . 8Be + 2H + Q 1 and 8Be ~ 2 4 H e 4 Q2. Fig. 1 shows the experimental arrangement. 40
P r o t o n s a c c e l e r a t e d by an e l e c t r o s t a t i c g e n e r a t o r to a p p r o x i m a t e l y 1.66 M e V a r e d i r e c t e d on a t h i n s e l f - s u p p o r t i n g Be f o i l (50 to 100 ~ g / c m 2) m o u n t e d a c r o s s the e n t r a n c e s l i t of a 180 ° h o m o g e n e o u s - f i e l d , m a g n e t i c s p e c t r o m e t e r of 1 m d i a m e t e r [2]. T h e e n e r g i e s of the i n c i d e n t p r o t o n s and of t h e r e a c t i o n d e u t e r o n s , and the m a x i m u m e n e r g y of the ~ p a r t i c l e s w e r e m e n -
PHYSICS
INTERNAL
MAGNETIC
LETTERS
FIELD
15 January 1966
OF
IODINE
IN
IRON
H. D E W A A R D and S. A. D R E N T J E
Natuurkundig Laboratorium, University of Groningen, The Netherlands R e c e i v e d 13 D e c e m b e r 1965
Large hyperfine fields a t nuclei of non-magnetic atoms in ferro-magnetic host lattices have been reported and discussed for a number of cases [1-5]. In particular, Frankel et al. [3] have studied the behaviour of hyperfine fields versus atomic number for nuclei ranging from Ru (Z =44) to Te (Z = 52), dissolved in iron and nickel. They have found a smooth variation of the field, with a change of sign near tin (Z = 50). A part of their results for solutions in iron is shown again in fig. i, with the addition of the value for iodine reported in this letter. The hyperfine field for iodine is derived from
a measurement of the Zeeman splitting of the 27.7 keV gamma transition of 129I dissolved in iron. This transition is excited in the decay of 33 day 129Te m, which activity was obtained by irradiating an enriched 128Te sample for one month at a neutron flux of 2 × 1014 cm-2s -I. Because of the rather low specific activity (about 0.2 mCi/mg) and the high chemical reactivity of tellurium with iron it was not attempted to dissolve the activity by normal means such as diffusion or making an alloy. It is believed that
Te 129 m in Fe HOST
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F i g . 1. H y p e r f i n e f i e l d s a t n o n - m a g n e t i c n u c l e i i n a n i r o n h o s t , v e r s u s a t o m i c n u m b e r . T h e s i g n of t h e f i e l d f o r C d , I n a n d I w h i c h h a s not been m e a s u r e d directly, is derived from the general trend. The data are from r e f . 3, e x c e p t f o r t h e i o d i n e p o i n t , w h i c h i s f r o m t h e present work.
38
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Fig. 2. M ~ s s b a u e r absorption s p e c t r a for two different v e l o c i t y r a n g e s obtained with a s o u r c e of 129Te m in iron and a K129I a b s o r b e r , both at about 100OK.
,:
Volume 20, number 1
PHYSICS
LETTERS
15 January 1966
t
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d _z MAGNETIC SPLITTING 1129 H=106 Oe
-5~o
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Fig. 3. Calculated absorption s p e c t r u m of 129I in a field of 106 Oe. P a r a m e t e r s used; magnetic moments
[9]: ~ = 2.617 n.m. (ground state), ~* = 2.84 n.m. (excited state), half-width of one component = 1.15mm/s (experimental value obtained with Zn129Te source and K129I absorber), source transversely magnetized. t h e s e p r o c e s s e s lead to the f o r m a t i o n of p a r a m a g n e t i c m i c r o c r y s t a l s of i r o n t e l l u r i d e s d i s p e r s e d in the iron. To avoid this as much as p o s s i b l e , the S c a n d i n a v i a n type isotope s e p a r a t o r of our Institute was u s e d to produce a s e p a r a t e d b e a m of 50 keV 129Te m ions that were shot into a 12 # thick foil of v e r y p u r e i r o n with a c a r e f u l ly c l e a n e d and etched s u r f a c e . In this way, s o u r ces of about 100 p C i w e r e obtained f r o m s e p a r a t o r r u n s l a s t i n g for about 8 hours. M b s s b a u e r s p e c t r a of such s o u r c e s were taken at a t e m p e r a t u r e of about 100OK, u s i n g a K129I single line a b s o r b e r , in a s i m p l e s t y r o f o a m c r y o s t a t v e r y s i m i l a r to one d e s c r i b e d e a r l i e r [6]. The s p e c t r o m e t e r was of the Kankeleit [7] type. Two s p e c t r a for different velocity r a n g e s a r e shown in fig. 2. The s p e c t r u m is i n t e r p r e t e d in the following way: (1) The c e n t r a l p a r t (a) r e s u l t s f r o m Te a t o m s in n o n - m a g n e t i c or weakly m a g n e t i c s u r r o u n d i n g s . T h i s p a r t shows an i n c o m p l e t e l y r e s o l v e d quadrupole s t r u c t u r e , r e s e m b l i n g that found for i r o n - t e l l u r i d e s (to be r e p o r t e d elsewhere). D e s pite the m a s s s e p a r a t i o n , the amount of 128Te in the 129Te m m a y s t i l l be high enough to cause a p a r t i a l f o r m a t i o n of t e l l u r i d e s or n o n - m a g n e t i c c l u s t e r s of Te a t o m s . A rough e s t i m a t e , b a s e d on s e p a r a t o r r e s o l u t i o n and gas p r e s s u r e n e a r the ion s o u r c e , i n d i c a t e s that a few # g / c m 2 of 128Te m a y have been deposited at the 129Tern position. Combined with data on the d i s t r i b u t i o n of the Te a t o m s in the host, d e r i v e d f r o m the t a b l e s of Domey [8], we conclude that the Te c o n c e n t r a t i o n in the m a x i m u m of the d i s t r i b u t i o n
is a few atom p e r c e n t for our b e s t s o u r c e . P a r t of this can f o r m i r o n t e l l u r i d e s or t e l l u r i u m c l u s t e r s . T h i s i n t e r p r e t a t i o n is c o n f i r m e d by the o b s e r v a t i o n that another s o u r c e , made with a lower r e s o l u t i o n of the m a s s s e p a r a t o r y i e l d s a s p e c t r u m with a f r a c t i o n a l i n t e n s i t y of the c e n t r a l p a r t (a) of the s p e c t r u m l a r g e r by a f a c t o r of about 2. The ease with which nonf e r r o m a g n e t i c i r o n - t e l l u r i u m compounds a r e f o r m e d is f u r t h e r d e m o n s t r a t e d by the fact that a f t e r heating this s o u r c e for 15 m i n to 700°C, the outer l i n e s b, c, d and e of the s p e c t r u m , to be d i s c u s s e d next, have c o m p l e t e l y d i s a p peared. (2) The two c l e a r l i n e s b and c and the two b r o a d e n e d weak l i n e s d and e r e p r e s e n t p a r t of the s p e c t r u m expected for 129I n u c l e i in a strong magnetic hyperfine field (Hint). The t e l l u r i u m a t o m s giving r i s e to this p a r t p r e s u m a b l y r e place i r o n a t o m s in the i r o n lattice. F o r c o m p a r i s o n , the c a l c u l a t e d hyperfine s p e c t r u m of the 27.7 keV t r a n s i t i o n in 129I for a field Hint = 106 Oe is shown in fig. 3. In view of the l a r g e c o n t r i b u t i o n of the c e n t r a l p a r t of the s p e c t r u m and the low i n t e n s i t y of l i n e s d and e, no l e a s t s q u a r e s fit of the c a l c u l a t e d s p e c t r u m to the m e a s u r e d points was attempted. Instead, Hint was d e t e r m i n e d f r o m the d i s t a n c e Abc of l i n e s b and c, which c o r r e s p o n d s to 0.14 ~Hin tThe a v e r a g e of t h r e e m e a s u r e m e n t s yields Hint = (1.13+0.04) x 106 Oe. This r e s u l t p r o v i d e s a smooth continuation of the t r e n d o b s e r v e d by F r a n k e l et al. [3]. A p p a r ently the effect on the field of adding e l e c t r o n s in 39
Volume 20, number 1
PHYSICS
the 5(sp) s h e l l i n c r e a s e s a s we a p p r o a c h the c l o s e d s h e l l e l e c t r o n c o n f i g u r a t i o n of xenon. A r e l e v a n t i t e m in t h i s r e s p e c t i s t h e p o s i t i v e e n e r g y s h i f t of 0.34 m m / s of the h y p e r f i n e p a t t e r n w i t h r e s p e c t to the K129I a b s o r b e r . F r o m a c o m p a r i s o n with o t h e r d a t a on the i s o m e r i c s h i f t s in 129I c o m p o u n d s [6] we l e a r n t h a t t h i s s h i f t c o r r e s p o n d s to an e f f e c t i v e n e g a t i v e c h a r g e of about - 0 . 7 5 e on t h e i o d i n e , a s s u m i n g t h a t t h e r e is no sp h y b r i d i z a t i o n . T h u s , t h e e l e c t r o n c o n f i g u r a t i o n of t h e I ion would b e t h a t of x e n o n w i t h ¼ of a p e l e c t r o n m i s s i n g . T h e i o n i c r a d i u s of s u c h an ion is about 2 ,~ and it w i l l h a r d l y f i t in the l a t t i c e . T h e r e w i l l be c o n s i d e r a b l e o v e r l a p of the 5s and 5p e l e c t r o n w a v e f u n c t i o n s w i t h t h o s e of the 3d e l e c t r o n s of t h e i r o n , l e a d i n g to a p o l a r i z a t i o n of e l e c t r o n s in the n = 5 s h e l l . T h e h y p e r f i n e f i e l d m a y be p a r t l y due to a d i r e c t c o n t a c t i n t e r a c t i o n of t h e p o l a r i z e d 5s e l e c t r o n s w i t h t h e n u c l e u s , p a r t l y to p o l a r i z a t i o n i n d u c e d in the c o r e by t h e n = 5 e l e c t r o n s . T h e f i r s t c o n t r i b u t i o n is p r o b a b l y p r e d o m i n a n t , but a u n i q u e i n t e r p r e t a t i o n a p p e a r s to b e i m p o s s i b l e at t h e m o m e n t , b e c a u s e q u a n t i t a t i v e c a l c u l a t i o n s of t h e v a r i o u s p o s s i b l e c o n t r i b u t i o n s a r e l a c k i n g [2, 5]. We s h o u l d l i k e to p o i n t out t h a t t h e s o - c a l l e d M o r i t a e x p e r i m e n t [10] on n o n - c o n s e r v a t i o n of p a r i t y s h o u l d be f e a s i b l e w i t h s o u r c e s of 129Tern in F e l i k e the o n e s d e s c r i b e d , p r o v i d e d the i n t e n s i t y of t h e a b s o r p t i o n l i n e s b and c c o u l d be in-
THE
Q VALUES
OF
THE
REACTION
LETTERS
15 January 1966
c r e a s e d to a f e w p e r c e n t , e.g. by u s i n g a l o w e r t e m p e r a t u r e and a s t i l l b e t t e r s o u r c e . We w i s h to t h a n k D r . R. M. H o u s l e y f o r h i s i n t e r e s t in t h i s w o r k and f o r u s e f u l s u g g e s t i o n s . T h i s i n v e s t i g a t i o n w a s m a d e p o s s i b l e by f i n a n c i a l support from the Foundation for Fundamental R e s e a r c h on M a t t e r (F. O. M.) s u b s i d i z e d by the Netherlands Organization for Pure Scientific R e s e a r c h (Z. W. O.). 1. p . N . Samoilov, V.V. Sklyarevskii and E. P. Sepanov, Zh. Experim. i Teor. Fiz. 36 (1959) 1944; 38 (1960) 359. 2. D.A. Shirley and G. A. Westenbarger, Phys. Rev. 138 (1965) A170. 3. R.B. Frankel, J. Huntzicker, E. Matthias, S.S. Rosenblum and D. A. Shirley, Physics Letters 15 (1965) 163. 4. M. Kontani, K. Asayama and J.Itoh, J. Phys. Soc. Japan 20 (1965) 1737. 5. A . J . F r e e m a n and R.E.Watson, in Magnetism, Ed. G. T. Rado and H. Suhl (Academic P r e s s , 1965} Vol. IIA, p.274. 6. D.W. Hafemeister, G. DePasquali and H. De Waard, Phys. Rev. 135 (1964) B1089. 7. E. Kankeleit, Rev. Sci. Instr. 35 (1964) 194. 8. B. Domey, Proc. fourth Scandinavian isotope separator symposium (Nobel Institute, Stockholm, 1963) nr. 4. 9. H. De Waard and J. Heberle, Phys. Rev. 136 (1964) B1615. 10. M.Morita, Phys. Rev. 122 (1961) 1525.
9Be(p,d)8Be
AND
8Be
~
2 4He
W. R E I C H A R T , H . H . S T A U B , H. STUSSI and F. Z A M B O N I Physik-Institut der Universit~tt Zi~rich
Received 15 December 1965
The following Q values have been measured absolutely- Q1 = 559.0 ± 1.1 keV for 9Be(p, d)SBe , Q2 92.6 * 0.8 keV for 8Be(C0 ~.
T h e f a i l u r e to f i n d a r e s o n a n c e in t h e e l a s t i c s c a t t e r i n g of a p a r t i c l e s on h e l i u m n e a r t h e a p a r t i c l e energT_ c o r r e s p o n d i n g to t h e a c c e p t e d Q v a l u e of t h e 8Be ~ 2~ r e a c t i o n , 94.7 + 0.6 k e V [1], p r o m p t e d t h e p r e s e n t r e d e t e r m i n a t i o n of t h e Q v a l u e s of the r e a c t i o n s 9Be + 1H - . 8Be + 2H + Q 1 and 8Be ~ 2 4 H e 4 Q2. Fig. 1 shows the experimental arrangement. 40
P r o t o n s a c c e l e r a t e d by an e l e c t r o s t a t i c g e n e r a t o r to a p p r o x i m a t e l y 1.66 M e V a r e d i r e c t e d on a t h i n s e l f - s u p p o r t i n g Be f o i l (50 to 100 ~ g / c m 2) m o u n t e d a c r o s s the e n t r a n c e s l i t of a 180 ° h o m o g e n e o u s - f i e l d , m a g n e t i c s p e c t r o m e t e r of 1 m d i a m e t e r [2]. T h e e n e r g i e s of the i n c i d e n t p r o t o n s and of t h e r e a c t i o n d e u t e r o n s , and the m a x i m u m e n e r g y of the ~ p a r t i c l e s w e r e m e n -