A. Penzo

Measurement of the spin correlation parameter A00kk for pp elastic scattering in the energy range 0.72–1.1 GeV

The spin correlation parameter A00kk (pp) has been measured in the angular region 45°<θCM<90° at 0.719, 0.834, 0.874, 0.934, 0.995 and 1.095 GeV using the SATURNE II polarized proton beam incident on a polarized target. The parameters A00nn(pp and A00sk(pp) were measured at 0.874 in the same angular region.

Measurement of the total cross section difference ΔαL(pp) in the energy range from 0.52 to 2.8 GeV

Abstract The total cross section difference ΔαL(pp) for proton-proton scattering with beam and target polarized longitudinally parallel and antiparallel, respectively, has been measured using the polarized proton beam from SATURNE II and a frozen spin polarized proton target. The beam polarization was reversed from pulse to pulse, and at each energy ΔαL was measured for both signs of target polarization. The data below 800 MeV confirm the previously observed structures. The cross section difference is found to change by 8.0 ± 0.5 mb between 520 MeV and 760 MeV. At the higher energies the results show no indication for similar structures or for a change of the sign of ΔαL.

Measurement of the spin correlation parameter Aoonn for pp elastic scattering in the energy range from 0.83 to 1.1 GeV

Abstract The spin correlation parameter A oonn (pp) and the analyzing power A oono (pp) have been measured in the angular region 45° θ CM

Measurement of np and pp asymmetry with an accelerated polarized deuteron beam from 725 to 1000 MeV per nucleon

Abstract The accelerated polarized deuteron beam of Saturn II was used to measure the analyzing power for np elastic scattering at five energies. The left-right asymmetries e = (L + R)/(L + R) for np and for pp elastic scattering were measured simultaneously by CH2− carbon subtraction using one of the beam-line polarimeters. The analyzing power A00n0(np) is given by the ratio enpd/eppd multiplied by the known analyzing power for pp elastic scattering. Experimental evidence is consistent with the underlying assumption that in the kinetmatic region of the experiment the ratio of the np to pp analyzing powers for scattering of quasifree nucleons in deuterons is the same as for scattering of free neutrons and protons, respectively.

Analysing power for quasi-elastic pp scattering in carbon and for elastic pp scattering on free protons

SummaryThe ratio of the analysing powers for quasi-elastic pp scattering in carbon and for elastic scattering on free protons was measured fromT = 0.52 to 2.8 GeV by scattering of the SATURNE II polarized proton beam on carbon and CH2. It was found to have a maximum at about 0.8 GeV. The energy dependence for quasielastic scattering on carbon had not been measured before above 1 GeV. The observed effect was not expected from simple models.

Polarization in backward elastic π+p scattering at 2.0, 3.5 and 4.0 GeV/c

Data on polarization in backward elastic π+p scattering at 2.0, 3.5 and 4.0 GeV/c are presented. The data at 2.0 GeV/c are compared with the result of a recent phase-shift analysis. Our data at 3.5 and 4.0 GeV/c, and existing data above 3 GeV/c, show no significant energy dependence of the polarization over the measured u-range. A comparison with Regge models and with results from amplitude analysis is made.

Determination of proton beam polarization at high energies by measurements after deceleration

Abstract We are investigating a new method to determine the polarization of proton beams accelerated to high energies by measurements after deceleration to low energies, where simple and precise techniques can be used based on the large and well known analyzing power of pp elastic scattering. The polarized proton beam of SATURNE II was accelerated to 520 MeV and its polarization was measured by extracting the beam onto the Nue5f8N beam line polarimeter.The beam was then accelerated to 800 MeV, decelerated to 520 MeV and again extracted. The loss in polarization is due to crossing twice the intrinsic depolarizing resonance γG = 3 at 631 MeV with adiabatic spin flip, once during acceleration and once during deceleration. The depolarization was intentionally increased by partially correcting the resonance, thus making the adiabatic flip less complete. The correction was introduced either at the rise or at the descent. The final polarization was the same in both cases showing that the depolarization was, as expected, the same during acceleration and deceleration. Another measurement was performed between 880 and 1200 MeV crossing successively two intrinsic resonances γG = ν z at ⋍900 Mev and γG = 4 at 1145 MeV. Here the polarization at 1200 MeV was measured directly and is compared to the value calculated from the measurements at 880 MeV before accelerating to 1200 MeV and after decelerating from 1200 MeV, assuming symmetric depolarization. The measured and the calculated values agree with ΔPB = 0.03 at P B ⋍ 0.75 .

Analysing power of reaction p↑C ⇒p′X from 0.52 to 2.8 GeV

SummaryThe emission of charged particles in proton-carbon interactions results from several different reactions: elastic or inelastic coherent scattering off the nucleus and elastic or inelastic scattering on quasi-free protons or neutrons. The polarized-beam asymmetry for the reaction p↑C ⇒- p′X involving all of these channels was measured at several laboratory angles between 11.6° and 73° at 20 energies from 0.52 to 2.8 GeV.

MEASUREMENT OF n-p AND p-p ASYMMETRY WITH ACCELERATED POLARIZED DEUTERON BEAM

The analyzing power for n-p e l a s t i c scat ter ing a t 725 MeV was determined by measuring the r a t io of n-p to p-p analyzing powers with 1450 MeV polarized deuterons from SATURNE I I and using the p-p analyzing power as r e ference. The nucleon polar izat ion in deuterons determined from the asymmetry 6p p agrees well with the value expected from d i rec t measurement of the deuteron beam vector polar iza t ion . We have determined the analyzing power for n-p e l a s t i c scat ter ing by measuring simultaneously p-p and n-p scat ter ing with quasi-free neutrons and protons in the SATURNE I I polarized deuteron beam incident on the NN beam l i n e polarimeter. The analyzing power Aoo l io(n-p) i s obtained d i rec t ly by multiplying the measured r a t i o e<L / 6 * by the known analyzing power AQOn0(p-p)• The method takes advantage of the fact that protons and neutrons in polarized deuterons have the same polar iza t ions . The r e s u l t ing systematic uncer ta in t ies of Ao o n o(n-p) are essen t ia l ly only those due to the uncertainty on A (p-p) . J oono r r The measurements presented here were carried out with the 1450 MeV polarized deuteron beam and are compared with those obtained with the 725 MeV polarized proton beam. F i r s t we have studied the counting r a t e s (Fig. 1) and asymmetries (Fig. 2) as funct ion of A 9 r e c = & 9COni , • Here 8 i s the angular posit ion of the recoi l arm and 9 c o n j # i s the conjugate angle for p-p e l a s t i c scat ter ing with respect to the forward arm posit ion a t 20.9° . Elas t ic p-p (n-p) scat ter ing of quasi free protons (neutrons) are shown in F ig . l b ( c ) . We observe prac t ica l ly no difference in the width of the peaks corresponding to scat ter ing on hydrogen. The counting ra tes from the carbon target a re essen t ia l ly the same for free and quasi-free incident protons but the hydrogen effect for quasi-free protons i s only about 2/3 of that for free proton beam. The r e l a t i ve ra tes of hydrogen and carbon events for quasi-free protons and quasi-free neutrons re f lec t the efficiency of 4 to 5 per cent of the neutron de tec tors . The measured asymmetries for two opposite beam polar izat ions are shown in Fig. 2 . The Figure shows also the asymmetries 6pn , 6fL, and £JL for scat ter ing on free target protons, calculated from the normalized CH2 C difference. In measurements Résumé Le pouvoir danalyse pour la diffusion n-p é las t ique à 725 MeV a été déterminé d après la mesure du rapport des pouvoirs danalyse n-p et p-p avec un faisceau de 1450 MeV de deutons polar isés ex t ra i t de SATURNE I I et en u t i l i s a n t l e pouvoir d analyse p-p comme base. La polar isa t ion des nucléons dans l e s deutons déterminée à pa r t i r de l asymétr ie p-p est en bon accord avec la valeur obtenue d après l a mesure d i rec te de la polar isa t ion vec to r i e l l e du faisceau de deutons . Article published online by EDP Sciences and available at http://dx.doi.org/10.1051/jphyscol:1985256 C2-464 JOURNAL DE PHYSIQUE with incident proton beam, one expects E t o be a constant throughout t h e e n t i r e width of t h e hydrogen peak. This i s i n fag! observed within e r r o r s (Fig. 2a) . The da ta fir both quasi-free incident protons and neutrons a r e cons i s ten t with independence on A0 only a t Aerec > 0 , whereas a t Aerec < 0 , €gp is strongly decreasing. For etdecthe s t a t i s t i c a l e r r o r s i n t h i s region a r e l a r g e and do not a l low t o draw any conclusion. Fig . 1 Counting r a t e s from CH2 and C t a r g e t f o r + and beam pola r iza t ion s t a t e a s a funct ion of t h e backward arm posi t ion. AQreC = 0 is t h e conjugate pos i t ion f o r e l a s t i c p-p s c a t t e r i n g . The forward arm is a t 20.9 l ab . a ) proton beam b) and c) deuteron beam a ) and b) two charged p a r t i c l e s detected c ) forward neutron and backward charged p a r t i c l e Fig. 2a,b,c Asymmetries ca lcu la ted from t h e da ta shown i n Figures l a , l b and l c , respec t ive ly . The d i f f e r e n t behaviour of tpp and ed a t AQreC < 0 could be due t o con t r ibu t ions t o the hydrogen e f f e c t from reac t ions o!Rers than p-p e l a s t i c s c a t t e r i n g (e.g. pp d T+) . The r e s u l t s of t h e measurements with deuteron beam of 1450 MeV a t t h r e e d i f f e r e n t forward angles with t h e r e c o i l protons a t Aerec = 0 a r e given in Table 1. The column 6 g ives t h e measured r a t i o €ip / tip . Using a t each angle t h e known va lues of t h e analyzing power Aoono(p-p) shown i n column 7 we obta in t h e analyzing powers Aoono(n-p) column 8 shown i n Fig. 3 together with t h e data from LAMPF (obtained with unpolarized neutron beam and polarized proton t a r g e t ) . Our r e s u l t s agree well with t h e LAMPF measurements and con£ i r m t h e i r abso lu te normalization. Rom t h e measured asmmetries ed and t h e h o r n analyzing power Aoono (p-p) ,we caleuPP d Table 1 Resul t s f o r t h e r a t i o E : ~ / L p and f o r t h e analyzing power Aoo,(n-p) . The l a s t column shows t h e beam nucleon po!arization deduced from these measurements.