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Submitted on 1 Jan 1973
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PRELIMINARY OBSERVATION OF HIGH TRANSVERSE MOMENTUM PARTICLE
PRODUCTION AT NAL (P. 455)
J. Cronin
To cite this version:
J. Cronin. PRELIMINARY OBSERVATION OF HIGH TRANSVERSE MOMENTUM PARTICLE PRODUCTION AT NAL (P. 455). Journal de Physique Colloques, 1973, 34 (C1), pp.C1-418-C1-420.
�10.1051/jphyscol:1973159�. �jpa-00215239�
J.iV. CRONIN
PRELIMINARY OBSERVATION OF HIGH TRANSVERSE MOMENTUM PARTICLE PRODUCTION AT NAL (P. 455)
J . W . CRONIN CHICAGO
We have measured a t NAL t h e y i e l d s of p a r t i c l e s produced a s a f u n c t i o n o f t r a n s v e r s e momentum i n p r o t o n - n u c l e u s c o l l i s i o n s . The o b s e r v a t i o n s were made i n t h e r e g i o n o f 90' i n t h e c e n t e r o f mass s y s t e m o f t h e i n c i d e n t p r o t o n and a s i n g l e n u c l e o n a t r e s t . We r e p o r t h e r e p r e l i m i n a r y r e s u l t s from a t u n g s t e n t a r - g e t bombarded by 200 and 300 GeV p r o t o n s .
F i g u r e 1 shows a schematic view of t h e a p p a r a t u s . We o b s e r v e p a r t i c l e s produced i n t h e l a b o r a t o r y a t a f i x e d a n g l e o f 77 mrad w i t h r e s p e c t t o t h e i n c i d e n t beam d i r e c t i o n . T h i s a n g l e c o r r e s p o n d s t o 77' and 88' r e s p e c t i v e l y f o r r e l a t i v i s t i c p a r t i c l e s i n t h e nucleon-nucleon c e n t e r o f mass system. The p a r t i c l e s a r e observed i n a s p e c t r o m e t e r which employs quadru- p o l e f o c u s i n g and two s u c c e s i v e magnetic d e f l e c t i o n s . P a r t i c l e s were i d e n t i f i e d by t h e downstream Cerenkov c o u n t e r . The s o l i d a n g l e o f t h e s p e c t r o m e t e r was AQ = 17 p t e r . The momentum a c c e p t a n c e was
Ap/p = 0 . 1 . We used s c i n t i l l a t i o n hodoscopes t o measure t h e momentum o f a n i n d i v i d u a l e v e n t w i t h a s t a n d a r d d e v i a t i o n of 1 %. More i m p o r t a n t l y we used t h e hodoscopes t o r e c o n s t r u c t t h e p o s i t i o n of e a c h e v e n t a t t h e t a r g e t w i t h a s t a n d a r d d e v i a t i o n of 1 cm h o r i z o n t a l l y and 2 nun v e r t i c a l l y . At h i g h t r a n s v e r s e momentum t h i s check was e s s e n t i a l t o e l i m i n a t e back- ground.
We reduced t h e d a t a t o e q u i v a l e n t c r o s s - s e c t i o n s on n u c l e o n s by t h e f o l l o w i n g formula :
where f i s t h e f r a c t i o n o f i n c i d e n t p r o t o n s t h a t i n t e r a c t , pL i s t h e observed l a b o r a t o r y momentum, and u i s t h e p r o t o n n u c l e o n c r o s s - s e c t i o n which
P
w e t a k e t o b e 40 mb. The f r a c t i o n f was computed t o b e 0.4 f o r a 5 cm long t u n g s t e n t a r g e t .
Vstlcdly quadrupoles
, r s n m t
Hadron c a l a i m e t s
qwdrupokl
F i g . 1.- NAL experiment 100 a p p a r a t u s .
Article published online by EDP Sciences and available at http://dx.doi.org/10.1051/jphyscol:1973159
HIGH TRANSVERSE MOMENTUM AT NAL C1-419
F i g u r e s 2 and 3 show t h e measured c r o s s - s e c t i o n s a s a f u n c t i o n o f t r a n s v e r s e momentum f o r n e g a t i v e and p o s i t i v e p i o n s .
F i g . 2 F i g . 3
F i g u r e s 4 and 5 show t h e measured r a t i o s o f Some a u x i l i a r y measurements w e r e made on b e r y l l i u m
', K-, P and P w i t h r e s p e c t t o p i o n s f o r t h e two and t i t a n i u m t o e s t a b l i s h t h a t none of t h e i m p o r t a n t n e r g i e s . f e a t u r e s d i s p l a y e d by t u n g s t e n w e r e d e p e n d e n t on
a t o m i c number.
p + W -, X + onything 300 GeV
0.01
0 1 2 3 4 5 6 7
P, (GeV/c)
F i g . 4
C1-420 J.W. CRONIN
The data show s e v e r a l important f e a t u r e s . (2) The K / n r a t i o s vary slowly with increasing (1) There i s an energy dependence of the cross-sec- transverse momentum, while P/ 'n and :/ < decrease
t i o n which grows stronger a s the transverse momentum with increasing transverse momentum.
increases. This i s i n q u a l i t a t i v e agreement with the (3) The r a t i o s p/nt and a r e strongly energy work of the Saclay-Strasbourg group [ I ] and t h e CERN- dependent.
~olumbia-Rockefeller group [2 ] a t the ISR.
REFERENCES
11 1 BANNER (M.) e t a l . , Phys. L e t t e r s (1973) 537 [2 1 B ~ ~ S S E R (F.W.) e t a l . , Paper no 204 (Submitted t o t h i s conference.
