Date

Polarization transfer in quasifree (p, n) reactions at 495 MeV

Chen, X.Y. ; Taddeucci, T.N. ; McClelland, J.B. ; et al.
Phys.Rev.C 47 (1993) 2159, 1993.
Inspire Record 369336 DOI 10.17182/hepdata.26026

A complete set of polarization-transfer observables has been measured for quasifree (p→,n→) reactions on H2, C12, and Ca40 at a bombarding energy of 495 MeV and a laboratory scattering angle of 18°. The data span an energy-loss range from 0 to 160 MeV, with a corresponding momentum transfer range of qc.m.=1.7–1.9 fm−1. The laboratory observables are used to construct partial cross sections proportional to the nonspin response and three orthogonal spin responses. These results are compared to the transverse spin response measured in deep inelastic electron scattering and to nuclear responses based on the random phase approximation. The polarization observables for all three targets are remarkably similar and reveal no evidence for an enhancement of the spin-longitudinal nuclear response relative to the spin-transverse response. These results suggest the need for substantial modifications to the standard form assumed for the residual particle-hole interaction.

3 data tables

No description provided.

No description provided.

No description provided.


Measurement of the polarization of tau leptons produced in Z decays

The ALEPH collaboration Decamp, D. ; Deschizeaux, B. ; Goy, C. ; et al.
Phys.Lett.B 265 (1991) 430-444, 1991.
Inspire Record 316781 DOI 10.17182/hepdata.29377

The polarization of τ leptons produced in the reaction e + e − → τ + τ − at the Z resonance has been measured using the τ decay modes e ν e ν τ , μν μ ν τ , πν τ , ϱν τ , and a 1 ν τ . The mean value obtained is P τ = −0.152±0.045, indicating that parity is violated in the neutral current process e + e − → τ + τ − . The result corresponds to a ratio of a neutral current vector and axial vector coupling constants of the τ lepton g V τ (M 2 Z ) g A τ (M 2 Z ) = 0.076±0.023 and a value of the electroweak mixing parameter sin 2 θ w ( M 2 Z ) = 0.2302 ± 0.0058.

2 data tables

Results are for both TAU+ and TAU- decay. Final combined result contains statistical and systematic errors added in quadrature.

No description provided.


Large $\chi_F$ Spin Asymmetry in $\pi^0$ Production by 200 GeV Polarized Protons

The E581 & E704 collaborations Adams, D.L. ; Akchurin, N. ; Belikov, N.I. ; et al.
Z.Phys.C 56 (1992) 181-184, 1992.
Inspire Record 314230 DOI 10.17182/hepdata.14557

The spin asymmetryAN for inclusive π0 production by 200-GeV transversely-polarized protons on a liquid hydrogen target has been measured at Fermilab over a wide range ofxF, with 0.5<pT<2 GeV/c. AtxF>0.3, the asymmetry rises with increasingxF and reaches a value ofAN=0.15±0.03 in the region 0.6<xF<0.8. This result provides new input regarding the question of the internal spin structure of transversely-polarized protons.

5 data tables

No description provided.

False asymmetry calculated for events with average beam polarization of zero.

No description provided.

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High precision measurement of A in large P(T)**2 spin polarized 24-GeV/c proton proton elastic scattering

Crabb, D.G. ; Kaufman, W.A. ; Krisch, A.D. ; et al.
Phys.Rev.Lett. 65 (1990) 3241-3244, 1990.
Inspire Record 299843 DOI 10.17182/hepdata.19939

We measured the analyzing power A out to P⊥2=7.1 (GeV/c)2 with high precision by scattering a 24-GeV/c unpolarized proton beam from the new University of Michigan polarized proton target; the target’s 1-W cooling power allowed a beam intensity of more than 2×1011 protons per pulse. This high beam intensity together with the unexpectedly high average target polarization of about 85% allowed unusually accurate measurements of A at large P⊥2. These precise data confirmed that the one-spin parameter A is nonzero and indeed quite large at high P⊥2; most theoretical models predict that A should go to zero.

1 data table

Errors quoted contain both statistical and systematic uncertainties.


Analyzing Power Measurement in Inclusive $\pi^0$ Production at High $\chi_F$

Bonner, B.E. ; Buchanan, J.A. ; Carey, D.C. ; et al.
Phys.Rev.Lett. 61 (1988) 1918, 1988.
Inspire Record 269386 DOI 10.17182/hepdata.2928

The analyzing power AN in inclusive π0 production has been measured with use of the new 185-GeV/c Fermilab polarized proton beam. We obtain the value AN=0.10±0.03 for π0's in the kinematic region 0.2<xF<0.8 and 0.3<pT<1.2 GeV/c. In certain models of particle production this suggests that the spin of the proton is carried by its valence quarks.

7 data tables

No description provided.

No description provided.

Individual polarisation measurements.

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The Acceleration of Polarized Protons to 22-{GeV}/$c$ and the Measurement of Spin Spin Effects in $p$ (Polarized) + $p$ (Polarized) $\to p + p$

Khiari, F.Z. ; Cameron, P.R. ; Court, G.R. ; et al.
Phys.Rev.D 39 (1989) 45, 1989.
Inspire Record 262472 DOI 10.17182/hepdata.23245

Accelerating polarized protons to 22 GeV/c at the Brookhaven Alternating Gradient Synchro- tron required both extensive hardware modifications and a difficult commissioning process. We had to overcome 45 strong depolarizing resonances to maintain polarization up to 22 GeV/c in this strong-focusing synchrotron. At 18.5 GeV/c we measured the analyzing power A and the spin-spin correlation parameter Ann in large- P⊥2 proton-proton elastic scattering, using the polarized proton beam and a polarized proton target. We also obtained a high-precision measurement of A at P⊥2=0.3 (GeV/c)2 at 13.3 GeV/c. At 18.5 GeV/c we found that Ann=(-2±16)% at P⊥2=4.7 (GeV/c)2, where it was about 60% near 12 GeV at the Argonne Zero Gradient Synchrotron. This sharp change suggests that spin-spin forces may have a strong and unexpected energy dependence at high P⊥2.

3 data tables

No description provided.

2.2 GeV point taken from Brown et al., PR D31(85) 3017.

No description provided.


Measurement of Spin Effects in $p$ (Polarized) $p$ (Polarized) $\to p p$ at 18.5-{GeV}/$c$

Crabb, D.G. ; Gialas, I. ; Krisch, A.D. ; et al.
Phys.Rev.Lett. 60 (1988) 2351, 1988.
Inspire Record 261135 DOI 10.17182/hepdata.20096

We measured the analyzing power A and the spin-spin correlation parameter Ann in medium-P⊥2 proton-proton elastic scattering, using a polarized-proton target and the 18.5-GeV/c Brookhaven Alternating-Gradient Synchrotron polarized-proton beam. We found sharp dips in both A and Ann, which occur at different P⊥2 values. The unexpected sharp structure in the spin-spin force occurs near P⊥2=2.3 (GeV/c)2 where the elastic cross section has no apparent structure.

1 data table

Errors contain both statistics and systematics.


Energy Dependence of Spin Effects in $p$ (Polarized) $p$ (Polarized) $\to p p$

Court, G.R. ; Crabb, D.G. ; Gialas, I. ; et al.
Phys.Rev.Lett. 57 (1986) 507, 1986.
Inspire Record 229812 DOI 10.17182/hepdata.20190

We measured the analyzing power A and the spin-spin correlation parameter Ann, in large-P⊥2 proton-proton elastic scattering, using a polarized-proton target and the polarized-proton beam at the Brookhaven Alternating-Gradient Synchrotron. We also used our polarimeter to measure A at small P⊥2 at 13 GeV with good precision and found some deviation from the expected 1Plab behavior. At 18.5 GeV/c we found Ann=(−2±16)% at P⊥2=4.7 (GeV/c)2. Comparison with lower-energy data from the Argonne Zero-Gradient Synchrotron shows a sharp and surprising energy dependence for Ann at large P⊥2.

3 data tables

POL is error weighted average of polarized beam and target measurements.

POL is error-weighted average of polarized beam and target measurements.

POL is error-weighted average of polarized beam and target measurement.


Measurement of the Analyzing Power for $p p$ (Polarized) $\to p p$ at $p^-$transverse**2 = 6.5-{GeV}/$c^2$

Cameron, P.R. ; Crabb, D.G. ; DeMuth, G.E. ; et al.
Phys.Rev.D 32 (1985) 3070, 1985.
Inspire Record 216507 DOI 10.17182/hepdata.23543

The spin analyzing power A in 28-GeV/c proton-proton elastic scattering was measured at P⊥2=6.5 (GeV/c)2 using a polarized proton target and a high-intensity unpolarized proton beam at the Brookhaven National Laboratory Alternating Gradient Synchrotron. The result of (24±8)% confirms that the analyzing power is large and rising in the large-P⊥2 region.

1 data table

No description provided.


MEASUREMENT OF P (POLARIZED) P (POLARIZED) ---> P P WITH A 16.5-GEV/C POLARIZED PROTON BEAM

Brown, K.A. ; Bruni, R.J. ; Cameron, P.R. ; et al.
Phys.Rev.D 31 (1985) 3017-3020, 1985.
Inspire Record 220234 DOI 10.17182/hepdata.23579

Using the new Brookhaven Alternating Gradient Synchrotron polarized proton beam and our polarized proton target, we measured the spin-spin correlation parameter Ann in 16.5-GeV/c proton-proton elastic scattering. We found an Ann of (6.1±3.0)% at P⊥2=2.2 (GeV/c)2. We also measured the analyzing power A in two independent ways, providing a good test of possible experimental errors. Comparing our new data with 12-GeV Argonne Zero Gradient Synchrotron data shows no evidence for strong energy dependence in Ann in this medium-P⊥2 region.

1 data table

ERROR CONTAINS BOTH SYSTEMATIC AND STATISTICAL UNCERTAINTY.