This work was supported by the National Science Foundation Grant NSF PHY 81-14339 and by Indiana Universit

Alford, W.P.

Boyd, R.N.

Foster, C.C.

Jeppesen, R.G.

Krofcheck, D.

Lind, D.A.

Sugarbaker, E.

Taddeucci, T.N.

Ullman, J.L.

Zafiratos, C.D.

English

IUScholarWorks

EXPLORATORY MEASUREMENTS OF THE ( 3 ~ e , n )  REACTION AT MEDIUM ENERGIES 
C.D. Zaf i r a tos ,  D.A. Lind, J.L. Ullman, and R.G. Jeppesen 
Univers i ty  of Colorado, Boulder, Colorado 80309 
E. Sugarbaker, R.N. Boyd, and D. Krofcheck 
Ohio S t a t e  Univers i ty ,  Columbus, Ohio 43212 
T. N. Taddeucci 
Ohio Univers i ty ,  Athens, Ohio 45701 
C.C. Foster  
Indiana Univers i ty  Cyclotron F a c i l i t y ,  Bloomington, Indiana 47405 
W.P. Alford 
Univers i ty  of Western Ontario,  London, Ontario,  Canada 
About nine  s h i f t s  of beam time were a l loca ted  t o  o v e r a l l  neutron re so lu t ion  was about 1.8 ns y ie ld ing  
run preliminary observat ions  of the  ( 3 ~ e ,  n )  r eac t ion  an energy reso lu t ion  of about 1 MeV. This was 
f o r  t a r g e t s  of 9 ~ e ,  12c, 2 4 ~ g ,  and 9 0 ~ r .  adequate f o r  an i n i t i a l  survey. The 9 ~ e ( 3 ~ e , n ) 1 1 ~  
Time-of-flight hu t s  a t  0" and 24" were instrumented so r eac t ion  a t  25 and 33 M e V  is s t rong  and q u i t e  adequate 
t h a t  angular d i s t r i b u t i o n s  could be taken from 0" t o  f o r  checking d e t e c t o r s  and e lec t ron ics .  At 80 MeV the  
48" where needed. Detector check-out and e f f i c i e n c y  y ie ld  was very small  compared t o  the  continuum 
measurements were done f i r s t  with the  ' ~ i  (p ,n)  r eac t ion  neutrons. 2~ gave s i g n i f i c a n t  y i e l d  i n d i c a t i n g  a 
a t  80 MeV. number of s t rong  s t a t e s  which appear a t  a l l  angles  out  
The exploratory inves t iga t ion  was motivated by the  t o  48". Angular d i s t r i b u t i o n s  a r e  not yet  a v a i l a b l e  t o  
l a r g e  number of high-lying s t a t e s  seen i n  our work a t  make comparisons wi th  known L t r ans fe r s .  2 4 ~ g  gave a 
25 MeV on s -p  s h e l l  nuc le i  and the  p red ic t ion  of very weak y i e l d  of d i s c r e t e  s t a t e s  a t  4.8 and 7.1 MeV 
Brogl ia  and ~ e s l  of the  ex i s t ence  of high-lying pa i r ing  while 9 0 ~ r  showed no y i e l d  from d i s c r e t e  groups. 
v i b r a t i o n s  involving coherent par t ic le-hole  p a i r s  These da ta  a r e  i n  the  process of ana lys i s  so  no 
ac ross  closed s h e l l s .  For poss ibly  d i f f e r e n t  reasons q u a n t i t a t i v e  r e s u l t s  a r e  avai lable .  At 80 MeV the 
n e i t h e r  the  ( 3 ~ e , n )  r eac t ion  a t  lower energies  nor the  r e so lu t ion  near t h e  ground s t a t e  was about 1 MeV while 
( p , t )  r eac t ion  have revealed the  ex i s t ence  of t h i s  a t  the  25 MeV energy it is about 0.3 t o  0.5 MeV and 
a d d i t i o n a l  s t rength.  Even though the  LEO s e l e c t i v i t y  inc reases  q u i t e  r ap id ly  wi th  e x c i t a t i o n  energy. Hence 
of the ( 3 ~ e , n )  r eac t ion  a t  lower energies  may not be d i s c r e t e  s t a t e s  should show up we l l  above the  continuum 
re ta ined  a t  80 MeV, a l a r g e  range of e x c i t a t i o n  energy a s  they do a t  25 MeV. However a t  80 MeV the y i e l d s  a r e  
should a l s o  be a v a i l a b l e  before the  low energy neutron much smal ler  than expected. Thus quest ions  of the  
emission overwhelms the  y i e l d  from d i s c r e t e  s t a t e s .  As reac t ion  mechanism and t h e  s t rong  energy dependence a r e  
pointed out by Kunz e t  a l e 2 ,  t h e  ca lcu la t ions  of the  ra ised.  However, b e t t e r  energy reso lu t ion  must be 
energy dependence of t h e  two nucleon t r a n s f e r  r eac t ions  achieved t o  i n t e r p r e t  adequately these  and f u t u r e  
us ing the  f i n i t e  range method have f a i l e d .  This experiments. 
experiment was designed t o  address t h a t  quest ion a s  
1)  R.A. Brogl ia  and D.R. Bes, Phys. Lett .  e, 129 
well .  (1977). 
The IUCF Cyclotron provided up t o  200 na average 2) P.D. Kunz, J.S. Vaagen, J.M. Bang, and 
B.S. Nilsson, Phys. Lett .  112B, 5 (1982). 
cu r ren t  i n  pulses  about 0.8 ns wide every 200 ns. The 
127  


Exploratory Measurements of the (3-He,n) Reaction at Medium Energies

https://scholarworks.iu.edu/dspace/bitstream/2022/2718/1/iucf_1982_127.pdf

Exploratory Measurements of the (3-He,n) Reaction at Medium Energies

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