Nikitin, V A

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I N V I T E D T A L K S p - p A N D p-tf SCATTERING AT SMALL ANGLES IN THE RANGE OF 8 - 7 0 GeV V. A. Nikitin The present repor t is based on papers [ 1 , 2, 3] s u b m i t t e d to this conference. Measurements of the elast ic sca t te r ing differential cross sect ion in the range of smal l four m o m e n t u m transfers , i . e. in the range of the interference of the nu­clear and Coulomb sca t t e r ing a m p l i t u d e , enable to de te rmine the va lue and sign of the real pa r t of the e las t ic sca t te r ing a m p l i t u d e . The dispersion re la t ion and Regge pole theor ies as well as the quas i -po ten t ia l model theory give some pre­dic t ions for the real pa r t of t he sca t te r ing a m p l i t u d e . Therefore i t is of great im­por tance to check some of these predic t ions expe r imen ta l ly . The exper imen t was performed at the Serpukhov accelerator . A hydrogen supersonic gas jet was used as a t a rge t . An in te rna l pro ton beam passed th rough the ta rge t m a n y t imes dur ing an in te rva l of 300 msec. The wid th of the ta rge t was about 3 cm. The exper imen ta l a r rangement as well as m a n y de ta i l s of the method used in th is exper iment were previously described [4—7] . The sca t te r ing angles of recoil par t ic les and the i r energies were measured by the sys tem of semi­conductor de tec tors . The inc iden t pro ton energy was de termined by the formula for i t s dependence on the magne t i c field of the accelerator . The proton energy increases a t ~ 6 GeV dur ing the working in te rva l of the jet ta rge t ( ~ 300 msec). The a d v a n t a g e of the hydrogen jet ta rge t can be seen in Fig . 1 . Here are plot­ted two spec t ra of recoil p ro tons , one obta ined in th i s exper iment and the other — in our previous exper iment wi th a th in polye thylene target [4] . A s p e c t r u m of recoil deuterons can be seen in Fig . 2. I t was obta ined using a deu te r ium gas jet t a rge t . 12* 3 5 5 F i g . 1 . T h e s p e c t r u m of reco i l p r o t o n s reg i s t ered b y t h e s e m i c o n d u c t o r d e t e c t o r s from t h e t h i n p o l y e t h y l e n e t a r g e t a) a n d h y d r o g e n jet t a r g e t b); c); d) are t h e b a c k g r o u n d s p e c t r a , r e s p e c t i v e l y . / i s t h e n u m b e r of the a m p l i t u d e c h a n n e l . F i g . 2 . T h e s p e c t r u m of reco i l d e u t e r o n s F i g . 3 . T h e d i f f eren t ia l cross s e c t i o n s of the p~p o b t a i n e d from the d e u t e r o n jet targe t a t e l a s t i c s c a t t e r i n g a t 70 GeV. t = 0 . 0 4 2 (GeVI cf. 356 F i g . 5 . T h e r a t i o a of t h e r e a l a n d i m a g i n a r y p a r t s of t h e p-p e l a s t i c f o r w a r d s c a t t e r i n g a m p l i t u d e p l o t t e d a g a i n s t t h e l a b o r a t o r y m o m e n t u m of t h e i n c i d e n t p r o t o n . T h e d o t t e d l i n e s s h o w t h e p o s s i b l e u n c e r t a i n t y i n t h e p r e s e n t e x p e r i m e n t a l d a t a d u e t o t h e error i n t h e u s e d v a l u e of t h e t o t a l p-p c r o s s s e c t i o n ± 1 mb. T h e s y s t e m a t i c errors of t h e d a t a [ 1 4 ] are a l s o i n d i c a t e d b y t h e d o t t e d l i n e s . T h e o r e t i c a l c u r v e s : d i s p e r s i o n r e l a t i o n s [ 9 ] . R e g g e p o l e s . E x p e r i m e n t a l d a t a o n a [ 1 4 ] i s t a k e n i n t o a c c o u n t t h e s a m e . D a t a o n a d o n o t t a k e n i n t o a c c o u n t [ 3 ] . F i g . 6 . T h e r a t i o a of t h e r e a l a n d i m a g i n a r y p a r t s of t h e p-d e l a s t i c f o r w a r d s c a t t e r i n g a m p l i ­t u d e p l o t t e d a g a i n s t t h e l a b o r a t o r y m o m e n t u m of t h e i n c i d e n t p r o t o n . T h e t h e o r e t i c a l d i s p e r s i o n c u r v e f r o m [ 1 0 ] i s g i v e n h e r e . A N . D a l -k h a z h a v e t a l . [ 1 7 ] . • I . M . G e s h -k o v e t a l . [ 1 9 ] , # p r e s e n t d a t a . 357 F i g . 4 , T h e d i f f e r e n t i a l c r o s s s e c t i ­o n s of t h e p-d e l a s t i c s c a t t e r i n g v a t 3 4 GeV. The differential cross sections of the p-p and p-d elastic scat ter ing were measured in the small range of the four momentum transfers of 0.001 <C \t \ <Z < 0.080 (GeV j cf. The differential cross sections of the p~p and p-d elastic scat ter ing in the region of the interference between the Goulomb and nuclear scat ter ing ampl i tude at 70 GeV and 34 GeV are shown in Figs. 3 and 4, respectively. The real par t of the p-p and p-d elastic scat ter ing ampl i tude was determined using the well known Bethe formula wi thout spin dependent terms: is the imaginary par t of the p—p elastic scat ter ing is the real par t of th is ampl i tude ; bj is the slope parameter; where ampl i tude ; is the Goulomb scattering ampl i tude; is the formfae-tor of the nucléon; is the scat te­ring angle in the c. m. s,; a is the nucléon radius; pc and k are the momentum and wave number of the proton in the c. m. s. The to ta l cross section, which determines the optical point (dG/dt09t, is calculated according to the extrapola t ion formula [14, 16, 18] . c0 = 38.25 mb; ct = 16.02 mb; n = 0.99. The parameters c and a were determi­ned using the least-square fit to the exper imental da ta . The uncer ta in ty in the quant i t ies (da/dt)opt and bj was taken into account. The parameter e, which gives absolute normal izat ion of the differential cross sections, was determined with a typical error of 2 — 4 % . The values of app and apd are plot ted versus in­cident proton energies for the p-p and p-d elastic scat ter ing, respectively (Figs. 5 and 6). The dispersion relat ion calculat ions [9—10] as well as the experimental da ta of other papers [11—16] are also shown. The calculat ion of app is presented in the paper [3] submit ted to th i s confe­rence. The summat ion of Regge-type diagrams was performed. Many-par­t icle vertices were evaluated tak ing into account experimental data on pion pro­duct ion. The result is shown in Fig. 5. The paper [2] by Ghernev et aL is devoted to measurements of the p-p and p-d elastic differential cross section in the region of 0.01 < | t \ < 0 . 1 2 (GeV/cf. Some emulsion cameras were exposed at the Serpukhov accelerator for these pur­poses. An internal film target was used. The ins ta l la t ion was the same as in [1, 4, 15, 171. The slope parameter involving in formula (1) is presented: 6™ = at the incident energy of at the incident energy of 70 GeV. The new value of bpp is in good ag­reement wi th the previous one 14J. I t is interest ing to compare the new value of bpd with the old one at 10 GeV [17]: a shrinkage ot the p-d scat ter ing dii iraction cone. The results of th is paper are only a par t of our exper imental da ta . The hand­l ing of remaining results is continuing. D I S C U S S I O N T e r - M a r t i r o s y a n : T h e o r e t i c a l c u r v e s for t h e e n e r g y d e p e n d e n c e of O t 0 t were o b t a i n e d c o n s i d e r i n g t h e R e g g e po le c o n t r i b u t i o n ( P , P \ GO, p , A2) and a l l re la ted b r a n c h e s . T h e effect of i n c r e a s i n g the branch 3 5 8 c o n t r i b u t i o n d u e t o t h e s h o w e r p r o d u c t i o n in t h e i n t e r m e d i a t e s t a t e s w a s t a k e n i n t o a c c o u n t . T h e n u m b e r of t h e p a r a m e t e r s c h o s e n i s t h e s a m e t h a t i n t h e R e g g e p o l e m o d e l a s t h e b r a n c h c o n t r i b u t i o n w a s c a l c u l a t e d o n t h e b a s i s of t h e e x p e r i m e n t a l d a t a o n t h e p a r t i c l e p r o d u c t i o n , p r o c e s s e s . T h e a t t e m p t s w e r e m a d e t o s h i f t t h e c u r v e s for cxtot i*1 t h e h i g h e n e r g y r e g i o n as far u p w a r d s as p o s s i b l e , b u t t h e y s h o w e d r e s i s t a n c e . W e fa i l ed t o d e s c r i b e t h e p r e v i o u s d a t a o b t a i n e d b y t h e S e r p u k h o v — C E R N g r o u p b u t , n e v e r t h e l e s s , s u b m i t t e d t h e w o r k t o t h e c o n f e r e n c e . H o w e v e r , t h e n e w d o t s for jt"~p g i v e n b y t h e S e r p u k h o v g r o u p h a v e s h i f t e d d o w n a n d t h e c o m p a r i ­s o n w i t h t h e m (carr ied o u t here i n K i e v ) s h o w e d g o o d a g r e e m e n t . I s h o u l d a l s o n o t e t h a t t h e R e g g e p a r a m e t e r s c o n t r i b u t i n g t o t h e c u r v e s for a t o t h a v e r e a s o ­n a b l e v a l u e s a n d w e l l d e s c r i b e a l l k n o w n d a t a o n 3t±iV, ^ ± N a n d NN e l a s t i c s c a t t e r i n g as w e l l do as ( R e A / I m A)t=o* t h e c u r v e — , p o l a r i z a t i o n a n d t h e d a t a o n c h a r g e e x c h a n g e r e a c t i o n s . CLJ* B a d a l y a n : W h a t i s t h e m a x i m u m d e n s i t y of t h e h y d r o g e n jet y o u o b t a i n e d ? N i k i t i n : T h e m a x i m u m d e n s i t y of t h e h y d r o g e n je t w a s 1 0 ~ 7 — „ a n d i t s d i a m e t e r e q u a l s 3 cm. R E F E R E R C E S 1 . V . D . B a r t e n e v e t a l . , p a p e r l a — 1 . 2 . K h . M. C h e r n e v e t a l . , p a p e r l a — 3 6 . 3 . V . L . L i s i n e t a l . , p a p e r l i a — 8 , K . G. B o r e s k o v e t a l . , p a p e r l i a — 9 . 4 . G. B e z n o g i k h e t a l . , Y a d e r n a y a F i s i k a 10, 1 2 1 2 (1969) ; P r e p r i n t J I N R E l — 4 6 2 8 (1969) ; G. G. B e z n o g i k h e t a l . , P h y s . L e t t . 30B, 2 7 4 (1969) . 5. V . A . N i k i t i n e t a l . S o v . P h y s . J E T P 46 , 1 6 0 8 ( 1 9 6 4 ) . 6 . L . S. Z o 1 i n e t a l . , C r y o g e n i c s , J u n e 1 9 6 8 , 1 4 3 . 7 . G. I . Z a b i y a k i n e t a l . , P r e p r i n t J I N R 1 3 — 3 3 9 7 (1967) . 8 . H . B e t h e . A n n . of P h y s . 3 , 190 (1958) . 9 . P . S ô d i n g . P h y s . L e t t . 8 , 2 8 5 (1964) . 1 0 . U . S. V e r n o v . Y a d e r n a y a F i s i k a ( U S S R ) 3 , 877 ( 1 9 6 6 ) . 1 1 . E . L o h r m a n e t a l . P h y s . L e t t . 13, 7 8 (1964) . 1 2 . G. B , a r o n i e t a l . N u o v o C i m . 3 8 , 95 (1965) . 1 3 . A . E . T a y 1 o r e t a l . P h y s . L e t t . 14, 5 4 (1965) . 1 4 . K . J . F o l e y e t a l . P h y s . R e v . L e t t . 19, 8 5 7 (1967) . 1 5 . L . F . K i r i 1 1 o v a e t a l . S o v . P h y s . J E T P 50 , 76 ( 1 9 6 6 ) . 1 6 . G. B e 1 1 e 1 1 i n i e t a l . P h y s . L e t t . 14, 1 6 4 (1965) ; P h y s . L e t t . 19, 7 0 5 ( 1 9 6 6 ) . 1 7 . N . D a 1 k h a z h a v e t a l . Y a d e r n a y a F i s i k a 8 , 3 4 2 (1968) ( U S S R ) . 1 8 . G. B i a 1 k o w s k i , S . P o k o r s k i . N u o v o C i m . 57A, 2 1 9 (1968) . 1 9 . I . M. G e s h k o v e t a l . P r e p r i n t J I N R P I — 4 8 9 4 (1970) . 

p-p and p-d scattering at small angles in the range of 8 - 70 GeV

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