The cross section for photoproduction of π0 mesons was measured at a photon energy of 3 GeV and squared four-momentum transfer (t) of -0.1 to -1.2 (GeV/c)2 using plane-polarized photons. The asymmetry was found to be consistent with +1.0 for t values above -0.4 and below -1.1. For −0.4<~t<~−1.0 there is a dip in the asymmetry and at t=−0.6 it drops to 0.55 ± 0.15. This result precludes a simple Regge model with ω0 and B; a theoretical description requires Regge cuts or an ω′ exchange.
No description provided.
MIT PREP (1967).
Measurements of the spin transfer parameters, K NN and K LL , at 500, 650 and 800 MeV are presented for the reaction p d → n pp at 0°. The data are useful input to the NN data base and indicate that the quasi-free charge exchange (CEX) reaction us a useful mechanism for producing neutrons with at least 40% polarization at energies as low as 500 MeV.
QUASI-FREE NP ELASTIC SCATTERING.
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Axis error includes +- 0.0/0.0 contribution (DUE TO QUAZIELASTIC BACKGROUND AND ERRORS IN POLARIZATION OF BEAM AND TARGET).
Axis error includes +- 0.0/0.0 contribution (DUE TO QUAZIELASTIC BACKGROUND AND ERRORS IN POLARIZATION OF BEAM AND TARGET).
Axis error includes +- 0.0/0.0 contribution (DUE TO QUAZIELASTIC BACKGROUND AND ERRORS IN POLARIZATION OF BEAM AND TARGET).
We present measurements for the baryon-exchange reaction π − p→ Λ K 0 at 5 GeV/ c over the range − u <2(GeV/ c ) 2 . The differential cross section is obtained from events produced on a liquid hydrogen target. These data are combined with events produced on a butanol polarized target and the parameters P , A , and R are then determined from an analysis of the decay angular distribution of the forward-going Λ. From our data it is possible to determine the magnitudes and the relative phase of the two invariant amplitudes A ′ and B . The consequences for the ratio B / A ′ are discussed in detail.
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THE ERRORS QUOTED IN D(SIG)/DU DO NOT INCLUDE THE ERROR ASSIGNED TO THE OVERALL U-INDEPENDENT CORRECTIONS FACTOR (4.62 +- 0.36), OR OTHER POSSIBLE NORMALIZATION ERRORS.
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As part of a program to determine proton-proton elastic-scattering amplitudes, we have measured the spin-spin correlation parameter CNN at 6 GeV/c. Measurements were made over the |t| range of 0.08 to 1.4 (GeV/c)2 using a polarized beam and a polarized target at the Argonne National Laboratory Zero Gradient Synchrotron.
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The polarization P in proton-proton elastic scattering has been measured at 3.83 GeV/ c for 0.35 ⩽ | t | ⩽ 3.0 (GeV/ c ) 2 , i.e. 29° ⩽ θ c.m. ⩽ 93°. The polarization shows a minimum at − ⋍ 1.0 ( GeV /c) 2 followed by a maximum at −⋍1.5 ( GeV /c) 2 . At the same energy the spin rotation parameter R has been measured in the interval 0.18 ⩽ | t | ⩽ 0.57 (GeV/ c ) 2 . Comparison with the results at 6.0 and 15.75 GeV/ c shows a similar t -dependence and the same average value at all three energies.
POLARIZED TARGET ASYMMETRY EQUALS RECOIL PROTON POLARIZATION BY TIME REVERSAL INVARIANCE.
'A'. 'B'. 'D'.
'A'. 'B'. 'C'. 'E'.
We have made the first measurement of the spin-spin correlation parameter CSS in pp elastic scattering at 6 GeV/c over the |t| range from 0.05 to 1.5 (GeV/c)2. The measured CSS data points are all negative, and their absolute values increase with |t|. The results are compared with some existing attempts to describe the pp scattering process.
NUMERICAL VALUES OBTAINED FROM AUTHORS. MAGNETIC FIELD ALIGNMENT AND APERTURE EFFECTS MEAN THAT QUANTITY ACTUALLY MEASURED IS 0.98 CSS + 0.02 CNN - 0.12 CSL. SEE LATER NUMBERS IN THE RECORD OF I. P. AUER ET AL., PL 70B, 475 (1977).
The differential elastic p−p scattering cross section was measured at 6 GeV/c at the Argonne Zero Gradient Synchrotron in the range p⊥2 = 0.6−1.0 (GeV/c)2 using a 65%-polarized target and a 75%-polarized extracted beam of intensity 3 × 109 protons/pulse. We simultaneously measured the polarization of the recoil proton with a well-calibrated carbon-target polarimeter. All three polarizations were measured perpendicular to the horizontal scattering plane. Our results indicate that P and T invariance are both obeyed to good precision even at large p⊥2. Parity invariance implies that the eight single-flip transversity cross sections are zero, so our data give the relative magnitudes of the eight remaining pure spin cross sections where all spins are measured. We find that the double-flip transversity cross sections are nonzero.
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The spin rotation sf R in pp and π + p elastic scattering at 45 GeV/c has been measured at the Seppukhov accelarator, for z . sfnc ; t |; ranging from 0.2 to 0.5 (GeV/) 2 . The results are presented, together with previous R measurements at lower energies. The equality of the values for R in proton-proton and pion-proton scattering, within the experimental errors, is a test of factorization of the residues in the pomeron exchange.
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The elastic cross section for proton proton scattering at 11.75 GeV/ c was measured at the Argonne ZGS using a 50% polarized target. In the range p ⊥ 2 =0.6 → 2.2 (GeV/ c ) 2 we obtained precise measurements of d σ d t(ij) for the ⇈ ⇊, and ⇅ initial spin states perpendicular to the scattering plane. We confirmed that the asymmetry parameter, A , decreases with energy in the diffraction peak, but is approximately energy-independent at large p ⊥ 2 . We found that the spin correlation parameter c nn acquires rather dramatic structure, and at large p ⊥ 2 seems to grow with energy.
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The polarized target asymmetry in the reaction γp→π°p has been measured at c.m. angles around 100° for photon energies between 0.4 and 1.0 GeV by detecting both the recoil proton and the π°. The result is compared with recent analyses.
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The spin rotation parameter R in elastic proton-proton scattering has been determined at incident momenta 6 and 16 GeV/ c in the interval from t = −0.18 (GeV/ c ) 2 to −0.54 (GeV/ c ) 2 . R pp at 16 GeV/ c is close to the val obtained for R in π − p elastic scattering at the same incident momentum. Equality of R pp ( s , t ) and R π p ( s , t ) is expected if Pomeron exchange dominates and if factorization holds. The t -dependence of R at 16 GeV/ c is consistent with weak helicity flip.
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We measured dσdt for p+p→p+p at 11.75 GeV/c using the zero-gradient synchrotron 70% polarized-proton beam and a 65% polarized-proton target. We obtained the spin-orbit asymmetry parameter A and the spin-spin correlation parameter Cm out to P⊥2=4.2 (GeV/c)2. We found that A drops smoothly towards zero, but that Cnn increases abruptly near P⊥2=3.6 (GeV/c)2, where the exp(−1.4P⊥2) component of elastic scattering becomes dominant. This suggests that large-P⊥2 "hard" elastic scattering may occur mostly when the two proton spins are parallel.
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We measured the cross section for proton-proton elastic scattering at 11.75 GeV/c using the Zero Gradient Synchrotron 52% polarized proton beam and a 60% polarized proton target. We measured dσdt(ij) in the ↑↑, ↓↓, and ↑↓ initial spin states perpendicular to the scattering plane in the range P⊥2=2.0−3.6 (GeV/c)2. We found that the asymmetry parameter A decreases smoothly with increasing P⊥2 in this range, and that the spin-spin correlation parameter Cnn may have a minimum near P⊥2=3 (GeV/c)2.
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The elastic cross section for proton proton scattering at 6 GeV c was measured using a 70% polarized beam and a 75% polarized target at the Argonne ZGS. In the range P ⊥ 2 = 0.5 → 2.0( GeV c ) 2 we obtained small error measurements for the ↑↑, ↓↓ and ↑↓ initial spin states perpendicular to the scattering plane. At P ⊥ 2 = 0.5 we also measured the recoil spin and found that the 5 different cross sections were very unequal.
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An experiment was done using an accelerated polarized proton beam and a polarized proton target. The elastic cross section for proton-proton scattering at 6.0 GeV/c and P⊥2=0.5−1.6 (GeV/c)2 was measured in the spin states ↑ ↑, ↓ ↓, and ↑ ↓ perpendicular to the scattering plane. The cross sections were found to be unequal by up to a factor of 2.
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We have measured the total cross-section difference for pp scattering in initial spin states parallel to the beam direction at beam momenta of 1.17, 1.47, 1.69, 1.97 and 2.49 GeV/ c . This measurement was done in a standard transmission experiment. A striking energy dependence is observed with a maximum difference of −16.9 mb at P lab = 1.47 GeV/ c .
PRELIMINARY RESULTS.
PRELIMINARY RESULTS.
We have remeasured the total cross section for proton-proton scattering at 2-6 GeV/c in the spin states ↑↑ and ↑↓ perpendicular to the beam direction. With the reduced errors significant differences were found between the two cross sections.
DIFFERENCE OF TOTAL CROSS SECTIONS FOR ANTIPARALLEL AND PARALLEL SPINS PERPENDICULAR TO THE BEAM DIRECTION.
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Using the polarized-beam facility at Argonne National Laboratory and a polarized proton target, simultaneous measurements of the spin parameter P and the spin correlation term CNN were made. Data were obtained and analyzed at beam momenta of 2, 3, 4, and 6 GeV/c in the momentum-transfer-squared interval 0.1≤|t|≤2.8 (GeV/c)2. A preliminary phase-shift analysis of the 2- and 3-GeV/c data is discussed and a comparison with predictions of a particular Regge-pole model at all four energies is made.
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We have measured the spin-spin correlation parameter CNN at 2, 3, 4, and 6 GeV/c over the |t| range of 0.1 to 2.0 (GeV/c)2 and have observed a striking energy and |t| dependence in CNN. Polarization data were simultaneously collected and are compared to previous results.
CNN PARAMETER MEASURED.
We have measured the difference between the pp total cross-sections for parallel and anti-parallel longitudinal spin states at beam momenta of 3 and 6 GeV/ c . These results, combined with our previous measurements, at lower momenta, are useful in clarifying a striking structure appearing at around 1.5 GeV/ c . We have also measured for the first time, the spin-spin correlation parameter C LL ( t ) in pp elastic scattering at 6 GeV/ c . We observe evidence for an exchange with A 1 -like quantum-numbers.
THE NEW DATA ON THE LONGITUDINAL CROSS SECTION DIFFERENCE, SIG(NAME=CLL) AT 3 AND 6 GEV ARE INCLUDED IN THE RECORD OF I. P. AUER ET AL., PL 67B, 113 (1977).
NOTE: HIGHER -T DATA ARE BEING ANALYSED. PUBLISHED GRAPH HAS LARGER ERRORS.
THESE NUMBERS APPEAR TO UPDATE THOSE REPORTED IN I. P. AUER ET AL., PRL 37, 1727 (76). NOTE: DATA MAY HAVE SMALLER ERROR BARS IN THE FINAL ANALYSIS.
The spin rotation parameter R has been measured at CERN, for π ± p at 6 GeV c and for π − p at 16 GeV c , with t ranging from −0.19 to −0.51 ( GeV c ) 2 . The parameter A was measured for π − p at 6 GeV c in the interval between t =−0.19 and minus;0.41 ( GeV c ) 2 . The averaged values are the following; R (+6) =−0.08±0.04, R (−6) =−0.23±0.05 and R (−16) =−0.23±0.05. The values obtained for A are close to +1.
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An experiment was done using the new accelerated polarized proton beam at the Argonne National Laboratory zero-gradient synchrotron and a polarized proton target. The total cross section for proton-proton scattering at 3.5 GeV/c was measured in the spin states ↑↑ and ↑↓ perpendicular to the beam direction. The two cross sections were found to be equal within the experimental error of ±5%.
TOTAL CROSS SECTION DIFFERENCE FOR PURE TRANSVERSE SPIN STATES.
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