We report the first measurements of the total cross section of the reaction K{sup -}p{yields}{sigma}{sup 0}{gamma} at eight beam momenta from 514 to 750 MeV/c. The data were obtained at the Alternating Gradient Synchrotron (AGS) at Brookhaven National Laboratory using the Crystal Ball detector consisting of 672 NaI crystals. All charged particles were vetoed by a barrel of plastic scintillators, resulting in a study of only the neutral decays of the {sigma}{sup 0}. The prompt photon and the photons from the decay products of {sigma}{sup 0} were detected for each reconstructed event; the neutron was also detected in a small fraction of the events.

The reaction K(-)p ->Sigma(0)pi(0)-> neutrals was studied with the Crystal Ball detector at the BNL Alternating Gradient Synchrotron for beam momenta between 514 and 750 MeV/c. The photons from Sigma(0) and pi(0) decays were detected, as well as the neutron in a small fraction of the events. The differential cross section and the Sigma(0) polarization are reported at eight momenta and nearly the full angular range. Total cross sections are derived from Legendre polynomial fits to the data. The measurements presented are of considerably higher precision than previous results.

The knowledge of the fluorescence emission as a function of atmospheric parameters is essential for the detection of extensive air showers with the fluorescence technique. In this paper, we summarize AIRFLY published measurements of the pressure dependence of the fluorescence yield. The spectral distribution of the fluorescent light between 280 and 429nm has been measured with high resolution. Relative intensities of 34 spectral lines have been determined. The pressure dependence of 25 lines was measured in terms of quenching reference pressures pλ′ in air. This set of AIRFLY measurements yields the most comprehensive parametrization of the pressure dependence of the fluorescent spectrum.

One of the goals of the AIRFLY (AIR FLuorescence Yield) experiment is to measure the absolute fluorescence yield induced by electrons in air to better than 10% precision. We introduce a new technique for measurement of the absolute fluorescence yield of the 337nm line that has the advantage of reducing the systematic uncertainty due to the detector calibration. The principle is to compare the measured fluorescence yield to a well known process—the Cherenkov emission. Preliminary measurements taken in the BFT (Beam Test Facility) in Frascati, Italy with 350MeV electrons are presented. Beam tests in the Argonne Wakefield Accelerator at the Argonne National Laboratory, USA with 14MeV electrons have also shown that this technique can be applied at lower energies.

The fluorescence detection of ultra high energy cosmic rays requires a detailed knowledge of the fluorescence light emission from nitrogen molecules over a wide range of atmospheric parameters, corresponding to altitudes typical of the cosmic ray shower development in the atmosphere. We have studied the temperature and humidity dependence of the fluorescence light spectrum excited by MeV electrons in air. Results for the 313.6, 337.1, 353.7 and 391.4 nm bands are reported in this paper. We found that the temperature and humidity dependence of the quenching process changes the fluorescence yield by a sizeable amount (up to 20% for the temperature dependence in the 391.4 nm band) and its effect must be included for a precise estimation of the energy of ultra high energy cosmic rays.

In the fluorescence detection of ultra high energy (≳1018eV) cosmic rays, the number of emitted fluorescence photons is assumed to be proportional to the energy deposited in air by shower particles. We have performed measurements of the fluorescence yield in atmospheric gases excited by electrons over energies ranging from keV to hundreds of MeV in several accelerators. We found that within the measured energy ranges the proportionality holds at the level of few %.

The fluorescence detection of ultra high energy (> 10^18 eV) cosmic rays requires a detailed knowledge of the fluorescence light emission from nitrogen molecules, which are excited by the cosmic ray shower particles along their path in the atmosphere. We have made a precise measurement of the fluorescence light spectrum excited by MeV electrons in dry air. We measured the relative intensities of 34 fluorescence bands in the wavelength range from 284 to 429 nm with a high resolution spectrograph. The pressure dependence of the fluorescence spectrum was also measured from a few hPa up to atmospheric pressure. Relative intensities and collisional quenching reference pressures for bands due to transitions from a common upper level were found in agreement with theoretical expectations. The presence of argon in air was found to have a negligible effect on the fluorescence yield. We estimated that the systematic uncertainty on the cosmic ray shower energy due to the pressure dependence of the fluorescence spectrum is reduced to a level of 1% by the AIRFLY results presented in this paper.

A polarized proton beam extracted from SATURNE II and the Saclay polarized proton target were used to determine the spin correlation parameter Aoosk and the rescattering observablesK os″ so; Dos″ok, Nos″sn, andN onsk at 1.80 and 2.10 GeV. The beam polarization was oriented perpendicular to the beam direction in the horizontal scattering plane and the target polarization was directed either along the vertical axis or longitudinally. Left-right and up-down asymmetries in the second scattering were measured. A check for the beam optimization with the beam and target polarizations oriented vertically provided other observables, of which results forD onon andK onno at 1.80, 1.85, 2.04, and 2.10 GeV are listed here. The new data at 2.10 GeV suggest a smooth energy dependence of spin triplet scattering amplitudes at fixed angles in the vicinity of this energy.

The analyzing powers of pi(+) and pi(-) were measured using an incident 22-GeV/c transversely polarized proton beam at the Brookhaven Alternating Gradient Synchrotron. A magnetic spectrometer measured pi(+/-) inclusive asymmetries on a hydrogen and a carbon target. An elastic polarimeter with a CH2 target measured pp elastic-scattering asymmetries to determine the beam polarization using published data for the pp elastic analyzing power. Using the beam polarization determined from the elastic polarimeter and asymmetries from the inclusive spectrometer, analyzing powers A(N) for pi(+/-) were determined in the x(F) and p(T) ranges (0.45-0.8) and (0.3-1.2 GeV/c), respectively. The analyzing power results are similar in both sign and character to other measurements at 200 and 11.7 GeV/c, confirming the expectation that high-energy pion inclusive analyzing powers remain large and relatively energy independent. This suggests that pion inclusive polarimetry may be a suitable method for measuring future beam polarizations at BNL RHIC or DESY HERA. Analyzing powers of pi(+) and pi(-) produced on hydrogen and carbon targets are the same. Various models to explain inclusive analyzing powers are also discussed.

Measurements at 18 beam kinetic energies between 1975 and 2795 MeV and at 795 MeV are reported for the pp elastic scattering spin correlation parameter A(00nn) = (N.N,0,0)= C-NN=A(NN). The c.m. angular range is typically 60 degrees -100 degrees. These results are compared to previous data from Saturne II and other accelerators. A search for energy-dependent structure at fixed c.m. angles is performed. Comparisons are made to phase shift analysis and theoretical model predictions of this spin observable.

Method and results of the beam polarization measurements are presented. The measurements were carried out at the proton polarized beam of Saturne-II accelerator as well as at the JINR (Dubna) synchrophasotron vector polarized deuteron beam. The analysis of the elastic (quasi-elastic) pp-scattering polarization is used as a method of the polarization measurements. The energy range of the measurement is 1.0≤ T p ≤2.8 GeV for polarized proton and 1.66≤ T d ≤7.3 GeV for polarized deuteron beams.

Measurements at 18 beam kinetic energies between 1975 and 2795 MeV and at 795 MeV are reported for the pp elastic-scattering single spin parameter Aooon=Aoono=AN=P. The c.m. angular range is typically 60–100°. These results are compared to previous data from Saturne II and other accelerators. A search for energy-dependent structure at fixed c.m. angles is performed, but no rapid changes are observed.Received 1 June 1999DOI:https://doi.org/10.1103/PhysRevC.60.054002©1999 American Physical Society

A polarized proton beam from SATURNE II, the Saclay polarized targets with \(^6\)Li compounds, and an unpolarized \(\mathrm{CH}_2\) target were used to measure spin-dependent observables for protons scattered on bound nucleons. The beam and target polarizations were oriented vertically. The analyzing power \(A_{\mathrm{oono}}\) and the depolarization \(D_{\mathrm{nono}}\) were determined at seven energies between 1.1 and 2.4 GeV. The spin correlation parameter \(A_{\mathrm{oonn}}\) was measured at only 1.1 and 1.6 GeV. Measurements with the \(\mathrm{CH}_2\) target at 1.1 GeV provided \(A_{\mathrm{oono}}\) data for scattering of polarized protons on neutrons in carbon. The quasi-elastic observables are compared with previous elastic scattering measurements and at 1.1 GeV with predictions of phase shift analyses.

A polarized proton beam extracted from SATURNE II, the Saclay polarized target with \(^6\)Li compounds, and a \(\mathrm{CH}_2\) target were used to measure elastic and quasi-elastic pp spin-dependent observables in the angular region \(60^{\circ} < \theta_{\mathrm{CM}} < 105^{\circ}\). The beam and/or target polarizations were oriented vertically. Accurate pp data for the analyzing power \(A_{\mathrm{oono}}\), spin-correlation parameter \(A_{\mathrm{oonn}}\), and the polarization transfer \(K_{\mathrm{onno}}\) were measured at 1.1 GeV. The observables \(A_{\mathrm{oono}}\) and \(K_{\mathrm{onno}}\) were determined at six other energies between 1.6 and 2.4 GeV. At 1.6 GeV, \(A_{\mathrm{oonn}}\) was also obtained. The individual contributions from H, \(^6\)Li, and \(^6\)LiD were deduced. The \(\mathrm{CH}_2\) target provided \(A_{\mathrm{oono}}(\mathrm{pp})\) results on free hydrogen and on protons in carbon. The elastic and quasi-elastic observables are compared with existing data and with phase-shift analysis predictions.

Experimental results are presented for the pp elastic-scattering single spin observable A(oono)=A(ooon)=A(N) =P, or the analyzing power, at 19 beam kinetic energies between 1795 and 2235 MeV. The typical c.m. angular range is 60-100 degrees. The measurements were performed at Saturne II with a vertically polarized beam and target (transverse to the beam direction and scattering plane), a magnetic spectrometer and a recoil detector, both instrumented with multiwire proportional chambers, and beam polarimeters. [S0556-2813(99)03610-9].