THE FIRST ACCELERATION TEST OF POLARIZED PROTONS IN KEK PS BOOSTER

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THE FIRST ACCELERATION TEST OF POLARIZED PROTONS IN KEK PS BOOSTER

S. Hiramatsu, H. Sato, T. Toyama, D. Arakawa, A. Ando, Y. Mori, A. Takagi, Z. Igarashi, K. Ikegami, H. Sakamoto, et al.

To cite this version:

S. Hiramatsu, H. Sato, T. Toyama, D. Arakawa, A. Ando, et al.. THE FIRST ACCELERATION

TEST OF POLARIZED PROTONS IN KEK PS BOOSTER. Journal de Physique Colloques, 1985,

46 (C2), pp.C2-529-C2-534. �10.1051/jphyscol:1985267�. �jpa-00224585�

JOURNAL DE PHYSIQUE

Colloque C2, supplément au n02, Tome 46, février 1985 page C2-529

THE F I R S T ACCELERATION TEST OF POLARIZED PROTONS I N KEK PS BOOSTER

S, Hiramatsu, H. S a t o , T. ~ o ~ a m a ' . D. Arakawa. A. Ando. Y . Mori, A. Takagi, Z . I g a r a s h i , K . Ikegami, H. sakamoto* and K. 1mai**

National Laboratory for High Energy Physics, Oho-machi, Tsukuba-gun, Ibaraki-ken, 305, Japan

* ~ s u k u b a University, Sakura-mura, Niihari-gun, Ibaraki-ken, 305, Japan

** Kyoto University, Sakyo-ku, 606, Japan

RESUME - La d é p o l a r i s a t i o n du f a i s c e a u de p r o t o n s p o l a r i s e s dans l e b o o s t e r

de ::?eV a é t é i n v e s t i g u é e comme p r e m i è r e é t a ? e p o u r l ' a c c é l é r a t i o n de p r o t o n s p o l a r i s é s au s y n c h r o t r o n d u KEK. La p o l a r i s a t i o n d u f a i s c e a u a é t é mesurée dans l a l i g n e de t r a n s p o r t de 20 YeV du l i n a c au b o o s t e r e t dans 1 'anneau p r i n c i p a l à 1 'é n e r g i e d ' i n j e c t i o n de 500 MeV. On garde e n v i r o n 40%

de l a p o l a r i s a t i o n du f a i s c e a u du l i n a c dans l ' a n n e a u p r i n c i p a l .

ABSTRACT - D e p o l a r i z a t i o n o f t h e p o l a r i z e d p r o t o n beam a c c e l e r a t e d i n t h e 500 MeV b o o s t e r was i n v e s t i g a t e d as t h e f i r s t s t e p o f p o l a r i z e d p r o t o n a c c e l e r a - t i o n i n t h e KEK p r o t o n s y n c h r o t r o n . Beam p o l a r i z a t i o n was measured i n t h e 20 MeV beam t r a n s p o r t l i n e f r o m t h e l i n a c t o t h e b o o s t e r and i n t h e main r i n g a t t h e i n j e c t i o n energy o f 500 MeV. About 40 % o f t h e l i n a c beam p o l a r i z a t i o n was k e p t i n t h e main r i n g .

INTRODUCTION

The p r o j e c t o f p o l a r i z e d p r o t o n a c c e l e r a t i o n i n t h e KEK 12 GeV p r o t o n synchro- t r o n (PS) began i n t h e f i s c a l y e a r 1980. A f t e r t h e c o n s t r u c t i o n s o f 750 keV pre- a c c e l e r a t o r and t h e 750 keV beam t r a n s p o r t l i n e f o r t h e p o l a r i z e d H- beam, t h e f i r s t a c c e l e r a t i o n t e s t was performed i n 1983 and d e p o l a r i z a t i o n i n he 500 MeV b o o s t e r s y n c h r o t r o n was i n v e - i g a t e d as t h e f i r s t s t e p o f t h i s program. 1 f

The p o l a r i z e d H beam i s produced i n t h e h i g h c u r r e n t p o l a r i z e d H- i o n source b y a 25harge-exchange r e a c t i o n w i t h Na v a p o r w h i c h i s o p t i c a l l y pumped b y dye l a - sers. The p o l a r i z e d H- beam i s c o n v e r t e d t o t h e p o l a r i z e d p r o t o n beam i n t h e b o o s t e r by a charge-exchange i n j e c t i o n t h r o u g h a t h i n carbon t a r g e t o f 120 vg/cm2 f o r t h e e l e c t r o n s t r i p p i n g . The p o l a r i z e d p r o t o n beam i s a c c e l e r a t e d up t o 500 MeV i n t h e b o o s t e r and t h e n i n j e c t e d i n t o t h e main r i n g .

P o l a r i z a t i o n o f t h e p o l a r i z e d p r o t o n beam d e p o l a r i z e s d u r i n g a c c e l e r a t i o n i n a s y n c h r o t r o n by c r o s s i n g d e p o l a r i z i n g resonances. I n t h e 500 MeV b o o s t e r o f t h e KEK PS, two s t r o n g depol a r i z i n g resonances must b.e c r o s s e d d u r i n g a c c e l e r a t i o n f r o m 20 MeV t o 500 MeV. I t i s d i f f i c u l t t o measure t h e d e p o l a r i z a t i o n o f each d e p o l a r i z i n g resonance i n d e p e n d e n t l y i n t h e b o o s t e r because t h e b o o s t e r i s r a p i d c y c l i n g synchro- t r o n o f 20 Hz and t h e a c c e l e r a t e d beam i s s h a r p l y bunched (severa) t e n s nsec). Thus beam p o l a r i z a t i o n was measured a t 20 MeV i n t h e beam l i n e f r o m t h e l i n a c t o t h e b o o s t e r and a t 500 MeV i n t h e main r i n g by u s i n g t h e c o a s t i n g beam f o r t h e i n v e s - t i g a t i o n o f d e p o l a r i z a t i o n i n t h e b o o s t e r . One o f two s t r o n g d e p o l a r i z i n g reso- nances i n t h e b o o s t e r i s i m p e r f e c t i o n resonance due t o v e r t i c a l c l o s e d o r b i t d i s - t o r t i o n (COD) and t h e o t h e r i s i n t r i n s i c resonance due t o v e r t i c a l b e t a t r o n o s c i l - l a t i o n . I n o r d e r t o i n v e s t i g a t e t h e s e resonances, t h e f a s t r o t a r y beam s c r a p e r w h i c h reduces t h e v e r t i c a l beam s i z e t o any s i z e a t any energy d u r i n g a c c e l e r a t i o n and t h e p u l s e d v e r t i c a l d e f l e c t i o n magnet which generates t h e maximum v e r t i c a l COD o f about 7 mm (rms) were i n s t a l l e d i n t h e b o o s t e r .

+Gn l e a v e from Department of Physics, Nagoya U n i v e r s i t y , Chikusa-ku, Nagoya, 464, Japan

Article published online by EDP Sciences and available at http://dx.doi.org/10.1051/jphyscol:1985267

C2-530 JOURNAL DE PHYSIQUE

DEPOLARIZING RESONANCES I N THE BOOSTER

00th t h e booster and t h e main r i n g o f KEK PS a r e s t r o n g f o c u s i n g synchrotrons and t h e r e f o r e s t r o n g d e p o l a r i z i n g resonances a r e expected d u r i n g a c c e l e r a t i o n . Such d e p o l a r i z i n g resonances occur a t t h e resonance c o n d i t i o n s o f yG = nN+ v f o r i n - t r i n s i c resonance and yG = n f o r i m p e r f e c t i o n resonance. Where y i s ~ o r e n t f i f a c t o r , i s v e r t i c a l b e t a t r o n o s c i l l a t i o n frequency, N i s t h e s u p e r p e r i o d i c i t y o f t h e

2 -

machine, n i s an i n t e g e r and G = g/2 n e p o l a r i z a t i o n o f t h e beam a f t e r c r o s s i n g a d e p o l a r i z i n g resonance i s g i v e n by 3 k 4 )

where Po i s t h e i n i t i a l p o l a r i z a t i o n b e f o r e c r o s s i n g t h e resonance, c i s the r e - sonance s t r e n g t h and a i s t h e c r o s s i n g speed f o r t h e resonance. The resonance s t r e n g t h . i s p r o p o r t i o n a l t o t h e amplitude o f v e r t i c a l b e t a t r o n o s c i l l a t i o n f o r i n - t r i n s i c resonance and i s p r o p o r t i o n a l t o v e r t i c a l COD f o r i m p e r f e c t i o n resonance.

D e p o l a r i z a t i o n i s small f o r small c 2 / a as i n t h e case o f weak resonance o r r a p i d resonance crossing. On t h e o t h e r hand p o l a r i z a t i o n f l i p s f o r l a r g e a. ^Therefore

small d e p o l a r i z a t i o n i s a l s o expected by s p i n - f l i p i n c r o s s i n g t h e s t r o n g d e p o l a r i z - i n g resonance (P - Po f o r e 2 / a >> 1).

imperfecl l

I

'ion

9 9 % spin f l i ~

' ^{i l m m )} 10% depol.

- ____----_--_-____ - - --.

F i g . 1 Strengths o f d e p o l a r i z i n g resonances i n t h e booster.

I n t h e booster o f KEK PS, two s t r o n g d e p o l a r i z i n g resonances, one i n t r i n s i c

resonance (yG = v ) a t about 260 MeV and one i m p e r f e c t i o n resonance (yG = 2) a t 108

MeV, must be crosSed d u r i n g a c c e l e r a t i o n . F i g u r e 1 shows t h e c a l c u l a t e d resonance

strengths o f s t r o n g d e p o l a r i z i n g resonances. 1 ) The maximum amplitude o f v e r t i c a l

b e t a t r o n o s c i l l a t i o n corresponding t o t h e maximum v e r t i c a l acceptance o f 49 II mm

mrad a t 20 MeV and a d i a b a t i c damping o f t h e b e t a t r o n o s c i l l a t i o n are assumed i n t h i s

c a l c u l a t i o n . The s t r e n g t h o f i n t r i n s i c resonance i s so s t r o n g t h a t t h e s p i n f l i p s

almost compl e t e l y i n passing through the resonance. The i m p e r f e c t i o n resonance i s

c a l c u l a t e d f o r t h e v e r t i c a l COD o f 1 mm (rms) and 5 mm (rms), r e s p e c t i v e l y . Large

d e p o l a r i z a t i o n i s expected even i f COD i s c o r r e c t e d t o l e s s t h a n 1 mm. On t h e o t h e r

hand s p i n - f l i p seems t o be f e a s i b l e i f COD i s l a r g e r than 5 mm. The synchrotron

o s c i l l a t i o n w i l l a l s o a f f e c t t h e beam p o l a r i z a t i o n i n t h e resonance c r o s s i n g by

s p i n - f l i p because t h e c r o s s i n g time across t h e resonance w i d t h (ay = 7.02 E/G) i s

l o n g e r than the p e r i o d o f synchrotron o s c i l l ' a t i o n . The a c c e l e r a t i n g RF v o l t a g e

should be reduced i n o r d e r t o a v o i d d e p o l a r i z a t i o n by synchrotron o s c i l l a t i o n i n

t h i s scheme o f resonance crossing.

POLARIMETERS

P o l a r i z a t i o n o f t h e p o l a r i z e d p r o t o n beam i s measured a t 20 MeV beam 1 in e and a t t h e main r i n g . P o l a r i z a t i o n o f t h e l i n a c beam i s measured by t h e 20 MeV p o l a r i - m e t e r which i s p l a c e d i n t h e s c a t t e r i n g chamber o f 655 mm i n d i a m e t e r i n s t a l l e d i n t h e 20 MeV beam l i n e f r o m t h e l i n a c t o t h e b o o s t e r . The l e f t - r i g h t asymmetry o f e l a s t i c s c a t t e r i n g e v e n t s a t a l a b o r a t o r y a n g l e o f 90" f r o m p r o t o n - c a r b o n s c a t t e r i n g i s measured by u s i n g a carbon f i b e r t a r g e t o f 100 um i n d i a m e t e r . The d e t e c t o r con- s i s t s o f a p a i r o f 1500 um s u r f a c e b a r r i e r SSD's and a p a i r o f d o u b l e s l i t s w i t h 5 mm d i a m e t e r h o l e s as shown i n F i g , 2. The d i s t a n c e between t h e t a r g e t and SSD i s 235 mm.

SLlT i 5mm dia.) 1 5 0 0 p m SURFACE BARRIER

BEAM PIPE

\

s c A n E k N G TARGE*

CHAMBER CARBON FIBER

1 6 5 5 m m dia.) (lOOpm dia. )

F i g . 2 20 MeV p o l a r i m e t e r .

An i n t e r n a 1 p o l a r i m e t e r ( t h e main r i n g p o l a r i m e t e r ) i s i n s t a l l e d i n t h e l o n g s t r a i g h t s e c t i o n I I - E F o f t h e main r i n g t o measure t h e a b s o l u t e p o l a r i z a t i o n o f c i r c u l a t i n g beam. It c o n s i s t s o f a p o l y e t h y l e n e s t r i n g t a r g e t o f 150 pm i n d i a m e t e r and t h e f o r w a r d and backward s c i n t i l l a t i o n c o u n t e r t e l e s c o p e s . The p o l a r i z a t i o n i s measured f r o m t h e asymmetry o f p r o t o n - p r o t o n e l a s t i c s c a t t e r i n g . F i g u r e 3 i s t h e schematic o f t h e main r i n g p o l a r i m e t e r . The s c a t t e r e d e v e n t s a r e d e t e c t e d by two f o r w a r d c o u n t e r t e l e s c o p e s and two backward t e l e s c o p e s . The e l a s t i c e v e n t i s i d e n t i f i e d b y t h e c o i n c i d e n c e o f t h e f o r w a r d s c a t t e r e d p r o t o n and t h e backward one.

The d e t e c t i o n a n g l e and t h e d i s t a n c e between s c i n t i l l a t o r s and t h e t a r g e t a r e ad- j u s t e d t o measure t h e asymmetry a t t h e momentum t r a n s f e r o f t = - 0.15 ( G ~ V I C ) ~ f o r t h e energy range f r o m 500 MeV t o 7 GeV. The c o p l a n a r i t y o f s c a t t e r e d and r e c o i l p r o t o n s i s checked t o s e p a r a t e t h e p r o t o n - p r o t o n e l a s t i c s c a t t e r i n g f r o m p r o t o n - carbon r e a c t i o n s i n t h e p o l y e t h y l e n e t a r g e t .

The beam p o l a r i z a t i o n was measured i n t h e main r i n g w i t h t h e c o a s t i n g beam a t 500 MeV. The c o p l a n a r i t y measurement shows t h a t t h e e l a s t i c e v e n t s a r e c l e a r l y observed and t h e background r a t e i s l e s s t h a n a few p e r c e n t s a t 500 MeV. The beam p o l a r i z a t i o n i n t h e main r i n g i s measured i n a few minutes w i t h t h e s t a t i s t i c a l a c c u r a c y o f ; 2 %. The asymmetry o f t h e p o l a r i m e t e r measured by t h e u n p o l a r i z e d beam i s l e s s t h a n 0.2 %. The d e t a i l s o f t h e main r i n g p o l a r i m e t e r i s r e p o r t e d i n r e f e r e n c e 5.

INTENSITY OF POLARIZED PROTON BEAM

D e p o l a r i z a t i o n i n t h e b o o s t e r s y n c h r o t r o n was s t u d i e d as t h e f i r s t s t e p o f p o l a r i z e d p r o t o n a c c e l e r a t i o n i n t h e KEK PS. The i n t e n s i t i e s o f p o l a r i z e d p r o t o n beam a t t h e v a r i o u s stages o f t h e a c c e l e r a t o r were

ION SOURCE (H?, 750 keV) 5 - 10 uA ( p u l s e d u r a t i o n 75 p s e c ) , L INAC ( H + , 20MeV) 0.5 - 1 P A ,

BOOSTER (P +, 500 MeV) 1 - ^{3 x} 108 p r o t o n s l b u n c h , MAIN RING (P +, 500 MeV) 1 - 2 x 108 p r o t o n s l b u n c h .

S i n c e t h e s t u d y was j u s t a f t e r summer l o n g shutdown, we had many t r o u b l e s i n t h e

machine o p e r a t i o n and t h e beam i n t e n s i t y a f t e r t h e l i n a c was remarkably l o w e r t h a n

t h e expected one.

JOURNAL DE PHYSIQUE

O - 50 IOOcm

bockward orrn

proton bearn -

Fig. 3 Main r i n g polarimeter.

EFFECT OF RF VOLTAGE ON BEAM POLARIZATION

The main purpose o f t h e f i r s t a c c e l e r a t i o n t e s t was t o i n v e s t i g a t e d e p o l a r i z a - t i o n i n t h e booster. We had n o t i t i s t a l l e d any equipment t o reduce t h e depolariza- t i o n i n t h e booster because s p i n - f l i p i s expected f o r two s t r o n g resonances.

I n o r d e r t o i n v e s t i g a t e t h e e f f e c t o f synchrotron o s c i l l a t i o n , dependence o f beam p o l a r i z a t i o n on t h e a c c e l e r a t i n g RF v o l t a g e was r o u g h l y checked. Beam p o l a r - i z a t i o n depolarized almost compl e t e l y a f t e r a c c e l e r a t i o n i n t h e booster a t t h e ac- c e l e r a t i n g RF v o l t a g e f o r t h e normal RF operation. The RF v o l t a g e a t t h e resonance o f y G = v was about 20 kV (peak) i n t h i s RF operation. To i n v e s t i g a t e t h e e f f e c t o f acceler%ting RF v o l t a g e on t h i s resonance, t h e RF v o l t a g e was reduced t o about 9 kV a t t h i s resonance as shown i n Fig. 4. Beam p o l a r i z a t i o n o f about 12 % was ob- t a i n e d w i t h t h i s RF operation. Almost same p o l a r i z a t i o n was obtained f o r t h e RF v o l t a g e p a t t e r n as shown i n Fig. 5 i n which t h e RF v o l t a g e d u r i n g a c c e l e r a t i o n was reduced such as t h e RF bucket h e i g h t decreased t o 112 - 113 o f t h e RF bucket h e i g h t i n t h e normal RF operation. The r e d u c t i o n of l o n g i t u d i n a l acceptance by these RF operations caused beam l o s s o f 30 - 50 % i n t h e booster. The p o l a r i z a t i o n s o f t h e p o l a r i z e d beam a t 20 MeV and 500 MeV were

LINAC P(LINAC, 20MeV) = 47 r 6 - 56 1 8 % , MR P(MR, 500 MeV) = 12 + 2 - 15 + 2 %.

About 25 % o f t h e l i n a c beam p o l a r i z a t i o n was kept i n t h e main r i n g a t 500 MeV by reducing t h e a c c e l e r a t i n g RF v o l t a g e o f t h e booster:

P(MR, 500 MeV)/P(LINAC, 20 MeV) a 25 %.

RESULTS OF POLARIZATION MEASUREMENTS

I n order t o i n v e s t i g a t e t h e resonance s t r e n g t h , t h e dependences o f t h e beam p o l a r i z a t i o n on v e r t i c a l beam s i z e and on v e r t i c a l COD i n t h e booster were measured.

F i g u r e 6 i s t h e dependence o f t h e p o l a r i z a t i o n on v e r t i c a l beam size. Beam s i z e was

v a r i e d by using t h e f a s t r o t a r y beam scraper which scraped t h e beam b e f o r e c r o s s i n g

t h e i n t r i n s i c resonance (yG = v ). P o s i t i v e p o l a r i z a t i o n i n t h i s f i g u r e i n d i c a t e s

t h a t beam p o l a r i z a t i o n f l i p p e d t 6 i c e by c r o s s i n g two s t r o n g resonances. T h i s r e s u l t

shows t h a t s p i n i s f l i p p e d by passing through t h i s resonance u n t i l t h e v e r t i c a l beam

emittance decreases t o about 1/100 o f the usual one. Thus t h e s t r e n g t h o f i n t r i n s i c

s p i n resonance i s s t r o n g enough f o r t h e resonance c r o s s i n g by s p i n - f l i p . I f v e r t i -

c a l beam s i z e i s blowed up t o 1.5 - 2 times by t h e RF knock-out method o r so,

s p i n - f l i p becomes more complete.

F i g . 4 The a c c e l e r a t i n g RF v o l t a g e o f F i g . 5 The RF v o l t a g e f o r a c c e l e r a t i o n t h e b o o s t e r . The RF v o l t a g e i s reduced of p o l a r i z e d p r o t o n s . The RF v o l t a g e i s a b o u t 9 kV a t t h e resonance o f yG = vZ. reduced d u r i n g a c c e l e r a t i o n and i s about H o r i z o n t a l s c a l e i s 2 m s e c l d i v . 10 kV a t t h e resonance o f yG = v

z '

- 5

,

1, , , , , ,

8 6 4 2 0

VERTICAL BEAM SIZE (mm) H L BEAM

( ^SCRAPER POSITION FROM

BEAM CENTER ^CENTER

VERTICAL DEFLECTOR (DIPOLE M G . ) CURRENT i A

F i g . 6 Dependence o f beam p o l a r i z a t i o n F i g . 7 Dependence o f beam p o l a r i z a - a t 500 MeV on t h e v e r t i c a l beam s i z e i n t i o n a t 500 MeV on t h e e x c i t a t i o n c u r - t h e b o o s t e r . r e n t o f t h e v e r t i c a l d e f l e c t i o n magnet

i n t h e b o o s t e r .

F i g u r e 7 shows t h e measured p o l a r i z a t i o n vs. t h e e x c i t a t i o n c u r r e n t o f t h e v e r - t i c a l d e f l e c t i o n magnet which produces v e r t i c a l COD. When t h e e x c i t a t i o n c u r r e n t was n e g a t i v e , p o l a r i z a t i o n was f l i p p e d by p a s s i n g t h r o u g h t h e i m p e r f e c t i o n reso- nance. On t h e o t h e r hand p o l a r i z a t i o n was k e p t w i t h o u t s p i n - f l i p i n p a s s i n g t h r o u g h t h i s resonance a t t h e e x c i t a t i o n c u r r e n t o f 169 A. The measured p o l a r i z a t i o n i n t h e main r i n g i s n e g a t i v e a t t h i s c u r r e n t because s p i n i s f l i p p e d by i n t r i n s i c resonance o n l y . T h i s r e s u l t shows t h a t v e r t i c a l COD i n t h e b o o s t e r i s l a r g e enough t o pass t h r o u g h i m p e r f e c t i o n resonance by s p i n - f l i p w i t h o u t t h e e x c i t a t i o n o f t h e v e r t i c a l d e f l e c t i o n magnet. A t t h e e x c i t a t i o n c u r r e n t o f 169 A, t h e i m p e r f e c t i o n resonance (yG = 2) became t o be weak s i n c e t h e second harmonic o f v e r t i c a l COD was reduced by t h i s magnet.

The measurement shows t h a t s p i n was a l m o s t c o m p l e t e l y f l i p p e d by two s t r o n g

resonances ( y G = 2, y G = v ) as expected f r o m t h e c a l c u l a t i o n . What i s t h e o t h e r

cause o f d e p o l a r i z a t i o n i n f h e b o o s t e r ? We aimed t o i n v e s t i g a t e thi\)yG = 5 - u

resonance a t a b o u t 450 MeV due t o t h e symmetry b r e a k i n g o f t h e machine. Toward t h 6

C2-534 JOURNAL DE PHYSIQUE

t o p energy t h e c r o s s i n g speed f o r t h i s resonance decreases since t h e magnet f i e l d o f t h e booster v a r i e s s i n u s o i d a l l y . Thus i n o r d e r t o increase t h e c r o s s i n g speed f o r t h i s resonance, t h e resonance energy was decreased by changing v w i t h the e x c i t a - t i o n o f a c o r r e c t i o n quadrupole magnet. F i g u r e 8 shows t h e depen8ence o f t h e p o l a r - i z a t i o n on t h e e x c i t a t i o n o f t h e c o r r e c t i o n quadrupole magnet. Beam p o l a r i z a t i o n increased by about 1.5 times a t t h e e x c i t a t i o n c u r r e n t o f 60 A. The c r o s s i n g speed f o r t h i s resonance increases about 10 % a t t h i s c u r r e n t . P o l a r i z a t i o n i n t h i s f i g u r e i s r e l a t i v e l y low because t h e Na vapor was trapped i n t h e p o l a r i z e d i o n source by sudden s t o p o f e l e c t r i c power caused from an earthquake. I f we had no such accident, p o l a r i z a t i o n would reach 20 - ^{25 %.} This r e s u l t shows t h a t about 40

% o f t h e l i n a c beam p o l a r i z a t i o n i s k e p t i n t h e main r i n g by t h i s small change o f v That i s ,

z '

P(MR, 500 MeV)/P(LINAC, 20 MeV) . i . 40 %.

O

O 20 40 60 80 100 QUADRUPOLE MAG. CURRENT ( A )

Fig. 8 Oependence o f beam p o l a r i z a t i o n on t h e e x c i t a t i o n c u r r e n t o f t h e c o r r e c t i o n quadrupole magnet.

D e p o l a r i z a t i o n by o t h e r weak s p i n resonances a r e n o t so l a r g e because t h e sextupole f i e l d , which was a p p l i e d by a small c o r r e c t i o n sextupole magnet, was n o t e f f e c t i v e f o r d e p o l a r i z a t i o n . I t i s expected t h a t t h e weak resonance due t o t h e symmetry breaking o f t h e machine causes l a r g e d e p o l a r i z a t i o n . Such d e p o l a r i z a t i o n i n t h e booster w i l l be solved by tune jump u s i n g t h e pulsed quadrupole magnets which w i l l be i n s t a l l e d i n 1984.

ACKNOWLEDGEMENTS

The authors wish t o acknowledge Professors S. Suwa, T. Nishikawa, T. Kamei, S.

Fukumoto and A. Masaike f o r t h e i r support t o t h i s work. Very h e l p f u l assistances o f Mr. T. Kawakubo, Dr. J. K i s h i r o and Mr. H. Yamaguchi w i t h t h e c o l l a b o r a t i o n i n p r e p a r i n g t h i s work and t h e s t a f f o f KEK PS w i t h the machine o p e r a t i o n a r e g r a t e f u l - l y acknowledged. Special thanks a r e due t o Dr. T.K. Khoe and Mr. K. Yokoya f o r t h e valuable discussions about d e p o l a r i z a t i o n i n KEK PS and Dr. N. Tamura f o r h i s h e l p f u l suggestions f o r t h e design o f t h e main r i n g polarimeter.

REFERENCES

1) S. Hiramatsu e t a l . , KEK 83-28, 1984.

2) Y. Mori e t a l . , Nucl. Instrum. and Methods, 220 (1984) 264; and Proc. o f t h e 3 r d Symp. on t h e Production and N e u t r a l i z a t i o n of t h e Negative Hydrogen Ions and Beams, BNL, 1983 (KEK P r e p r i n t 83-28, 1984).

3) M. F r o i s s a r t e t al., Nucl. Instrum. and Methods, 7 (1960) 297.

E. Grorud e t a l . , IEEE Trans. on Nucl. Sci. NS-26 (1979) 3209.

E.D. Courant e t a l . , BNL Report, BNL 51270, 1980.

4) E. Grorud e t a l . , Proc. o f the 5 t h I n t . Symp. on High Energy Spin Physics, BNL, 1982 (AIP Conf. Proc., No.95, 1982, p.407).

5) H. Sato e t a l . , KEK 83-27, 1984.