KEK ACTIVITIES WITH POLARIZATION PHENOMENA

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KEK ACTIVITIES WITH POLARIZATION PHENOMENA

N. Horikawa

To cite this version:

N. Horikawa. KEK ACTIVITIES WITH POLARIZATION PHENOMENA. Journal de Physique

Colloques, 1985, 46 (C2), pp.C2-411-C2-415. �10.1051/jphyscol:1985246�. �jpa-00224560�

KEK A C T I V I T I E S WITH POLARIZATION PHENOMENA

N. Horikawa

Department of Physios, Faculty of Science, Nagoya University, Nagoya 464, Japan

Résumé - Les expériences faites au KEK couvrent un vaste domaine de la phy- sique. Dans cet article, quelques résultats expérimentaux récents ainsi que les projets du KEK pour l'étude des phénomènes de polarisation dans les interactions NN et 'ÏÏN seront discutés.

Abstract - The experiments at KEK cover the wide range of physics interests.

In this paper, we introduce some experimental results concerning the polari- zation phenomena in N-N and N-N systems which have been performed in the past about two years, and also the experiments planned in the near future.

I. Introduction

The present experimental list in KEK includes some kinds of experiments in a various stages, that is, 2 theme in the running stage, 6 theme in the preparation one and nearly 20 theme in the analyzing one. Among these experiments, we would like to introduce firstly the experiments which have been performed for the past two years, and secondly the experiments which are scheduled in the near future, focusing on the polarization phenomena in N-N and N-N interactions.

I. Experiments Performed (1)

These experiments were performed by using the high momentum K-beam channel and the polarized deuteron target. As for the K

d process, the data are taken at ]?inc = 1.49 GeV/c and the preliminary result will be presented in this Symposium as a contributed paper. A-parameter for tr

d process was measured at P £

= 0.74 GeV/c in the angles between 6 ^

48° ^ 100°. Data were compared with Glauber predictions in Fig. 1, together with the data of da/dfl in the Ti

d process at Pi

=0.72 GeV/c.

Fig. 1 - The comparison with Glauber predictions. As wave function and TTN phase shifts, Hashimoto and Kanai et al. adopt Hamada-Johnston and Karlsruhe- Helsinki, Reid and Saclay types. Predictions include dibaryons.

Article published online by EDP Sciences and available at http://dx.doi.org/10.1051/jphyscol:1985246

C2-412 JOURNAL DE PHYSIQUE

The disagreement between data and predictions shows that the consistent pre- diction has not yet been obtained even in the two parameters of du/dR and A(8).

(2) Proton-Proton Scattering in the Energy Range of 0.9 2. 2.0 GeV/c/2,3/.

%ot

e OEp + ntdy ' P P + nopp9 upP + n+pn and d~(e)/dfl data for proton- proton scattering in t e energy range of 0.9

2.0 GeV/c were obtained by analyzing 220,000 pictures of lm bubble chamber. The data were compared with some analyses.

From those predictions, the following conclusions are derived.

(a) No structure for dibaryon is seen in any cross sections.

(b) The differential cross section for the elastic scattering is well reproduced by Hoshizaki's phase shift analysis+including ID and 3~3.

(c) For the inelastic processes, pp,+ ~r pn and pp + w pn proceed mainly 2 (% 80%) through intermediate states nA++ and pAO.

(dl Single pion production cross sections agree well with Verwest & Arndt analysis, and don't agree with Kijnig & Kroll. Verwest & Arndt analysis concluded no possibility of 1 = 0 dibaryon below 1.7 GeV/c. (Kb;nig & Kroll has tried a new analysis including 3 ~ 3 resonance and succeeded in the data reproduction/4/.) (3) Polarization of A" Inclusively Produced by 12 GeV/c Proton on Tungusten/5/.

The experiment was performed

at 3 production angles in the a

Fig. 2 - The PT depen- kinematical region of 0.4 2 ^{P T L o}

dence of A0 polariza- 1.6 GeV4c. The total number of

tion at 12 GeV in 2 . 4 ~ 10 A" is identified. As

comparison with higher-

seen from Fig. 2, the following $ energy data.

results are derived. 5

(a) The data are consistent

with previous one measured g

higher energies.

(b) PT dependence shows a ^-

tendency to level off for

PTL 1.0 GeV/c .

PT (GeV/C

(4) Ekperiments by Beam.

The recent experiments achieved by P are followings.

(i) PP 2 ^yX, a> nX and p X

(ii) uT(PP), a(P4). Forward do/dt(F~, Fd) _dU/dn, aabS(Pc, FA&, FCU)

do/dR(P_p + PP), du/dR(Pp + iin), d o / d n ( ~ ~

r+n-, ^du/dR(PP

K+K-) do/dR(PC

nX)

As some parts of these experiments are already published/6,7/, wereport the preliminary results now being analyzed.

(a) Forward ReallImaginary ratio for PP and Fn.

These werg measured in the incident momentum region of 350 2 Pinc 5 800 M~V/C.

The result of PP process is generally consistent with other data and the momentum dependence-is well ~redicted by the potential model as shown in Fig. 3(a). The result of Pn which is measured firstly in this energy region shows a positive sign near zero and has a tendency to decrease slowly with momentum. The potential model

fails to reproduce the data as seen in Fig. 3(b).

(b) Possible existence of a new meson resonance/8/.

The total and differential cross sections for FP+K+K- were measured at 0.39 2

Pinc (0.78 GeV/c. From a big enhancement at 490 MeV/c in UT and the special symmetrical feature in du/dR at the same momentum, a new meson resonance with following characteristics is suggested.

G +

Mass 2 ^{1935f 15 MeV,} r( ^{40 MeV, J~~ = 2++, I = 0 or 1-}

r e s p e c t i v e l y . Dashed l i n e i n PP denotes Lacombe e t a l .

IU . Experiments Planned.

A s experimental p l a n s which use t h e p o l a r i z e d beam f a c i l i t y , t h e following 3 experimental p l a n s were proposed.

(1) The Measurement of Spin C o r r e l a t i o n Parameter A,.,, a t l a r g e PT Region i n t h e pfnf ⁺ pn S c a t t e r i n g .

(2) The Measurement of Spin T r a n s f e r i n p f ~ ^-+ AI\IX Reaction.

( 3 ) The Acceleration of P o l a r i z e d Deuteron and Measurement of Physical Q u a n t i t i e s i n n f p Process Aiming a t Dibaryons i n I = 0 .

Among t h e s e experiments, only (1) theme i s accepted by PAC i n t h e l i m i t e d c o n d i t i o n t h a t t h e experiment must be r e a l l y f e a s i b l e i n c l u d i n g t h e c o n s t r u c t i o n of t h e p o l a r i z e d beam f a c i l i t y . Others a r e l e f t f o r t h e l a t e r chance. So we would l i k e t o mention about t h e (1) experiment.

Tne motivation i s following.

( i ) What behavior w i l l b e seen i n , , . A , a t l a r g e PT i n pn p r o c e s s ? Does "Anomaly"

appear i n pn, which i s observed I n pp p r o c e s s ?

( i i ) What kind of model i s p r e f e r a b l e t o t h e l a r g e PT r e g i o n i n hadron-hadron s c a t t e r i n g ?

As w e l l known, A,.,, i n pp e l a s t i c s c a t t e r i n g behaves e x t r a o r d i n a l l y a t l a r g e PT r e g i o n and some t h e o r e t i c a l models a r e proposed t o e x p l a i n i t . However, t h e g e n e r a l concensus t o t h e r e a c t i o n mechanism h a s n o t y e t been e s t a b l i s h e d . In Table I , t h e p r e d i c t i o n by s e v e r a l quark models a r e presented.

Table 1 - The prediction of Ann by quark model.

Model P-P P-n ( d ~ / d t ) " ~ / ( d o / d t ) ~ ~

Q I M A~~--AQL=-A,, A nn =-AQQ=-A ss

( F a r r a r e t a l . ) Ann(900)=1/3 Ann(900)=-0.44 a0.6 (Brodsky et al.)

Diquark spectator A =-0.22k0.22

model (Welters) nn

Q-Q scattering Ann= {I19 with color A =O

model (Chen) - 1 / 1 1 without color ""

C2-414 JOURNAL DE PHYSIQUE

The ~ l a n n e d experimental s e t up i s shown i n Fin. - 4 .

F i g . 4 - The beam l i n e and schematic l a y o u t of t h e a p p a r a t u s . To perform t h i s experiment, t h e f o l l o w i n g problems a r e expected.

( i ) Low beam i n t e n s i t y ( l o 8 pps) and small d a / d t a t Ocm= 90".

( i i ) Background e v e n t from p o l a r i z e d 'deuteron t a r g e t . ( i i i ) Neutron Fermi motion i n D and background n u c l e u s .

To overcome t h e s e problems and t o g e t a b e t t e r s t a t i s t i c a l e r r o r , one must t a k e c a r e of t h e f o l l o w i n g s u b j e c t s .

As f o r t h e ( i ) , t h e l a r g e PT, a n e u t r o n c o u n t e r w i t h h i g h e r d e t e c t i o n e f f i - ciency and t h e h i g h e r p o l a r i z a t i o n s of beam and t a r g e t a r e u s e f u l .

As f o r ( i i ) and ( i i i ) , t h e development of t h e p o l a r i z e d t a r g e t w i t h l e s s background nucl.ei and t h e p r e c i s e d e t e r m i n a t i o n of k i n e m a t i c s of e v e n t s a r e i n e v i t a b l e .

Following t h e s e requirements, we a r e now p r e p a r i n g some a p p a r a t u s , t h a t i s , ( i ) t h e p o l a r i z e d ND3 t a r g e t i n d i l u t i o n mode,

( i i ) t h e beam d e f i n i n g c o u n t e r i n t h e h i g h counting r a t e ,

( i i i ) S i - s t r i p d e t e c t o r f o r charged p a r t i c l e s around t h e t a r g e t and

( i v ) p o s i t i o n s e n s i t i v e neutron c o u n t e r c o n s i s t e d of t h e sandwich of i r o n p l a t e and t h e a r r a y o£ p l a s t i c streamer t u b e .

From t h e s i m u l a t i o n , i t i s found t h a t t h e most e f f e c t i v e method t o s e l e c t t h e r e a l event i s t o u s e t h e c o p l a n a r i t y r e l a t i o n between proton and n e u t r o n . I n Fig.

5, t h e event d i s t r i b u t i o n i n t h e coplanar plane i s shown.

F i g . 5 - Event d i s t r i b u t i o n from deuteron and n i t r o g e n a t ,= 8, 90'. 'Pg,(Pq

correspond t o azimuthal a n g l e of p r o t o n and n e u t r o n , r e s p e c t ~ v e l y . The s o l l d l i n e

means t h e c o p l a n a r i t y .

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8. Nakamura K . , Talk a t European A n t i p r o t o n Symposium, Durham, UK, 1984