O. B. van Dyck

Measurement of the p-C analyzing power between 100 and 750 MeV and the p-Be analyzing power at 780 MeV

Abstract The inclusive p-C analyzing power has been measured for laboratory scattering angles between 4° and 25°, for energies between 100 and 750 MeV. The inclusive p-Be analyzing power has been measured at 780 MeV between 4° and 28°. The experiment was performed at LAMPF using a large solid angle polarimeter. An energy dependent empirical fit to these data as well as to data from SIN and TRIUMF is presented. The data from all three facilities are in generally good agreement.

Some proton spin observables obtained in p-d elastic scattering at 500 and 800 MeV

Abstract Measurements of the spin transfer observables D NN , D SS , and D LS in p + d → p + d at 500 and 800 MeV are reported. In addition we have measured the polarization, P , and the asymmetry A y . The data were taken in the range 0.2 t c ) 2 . Comparison of the observables is made with the predictions of a relativistic multiple scattering model employing the results of a recent phase shift analysis of NN scattering data.

High Intensity Beam Profile Monitors for the LAMPF Primary Beam Lines

Two types of beam profile monitors are in use at LAMPF to measure the properties of the 800 MeV, 500 ¿A proton beam external to the linac. Both types use secondary electron emission from a wire to produce a current signal proportional to the amount of proton beam that intercepts the wire. The wire scanner system uses a pair of orthogonal wires which are passed through the beam and the harp system uses two fixed planes of parallel wires. Most of the harps are not retractable and are exposed continuously to the primary beam. The high beam intensities available lead to a number of technical problems for instruments that intercept the beam or are close to primary beam targets. The thermal, electrical, radiation-damage, and material selection problems encountered, and some solutions which have been implemented are discussed.

Measurement of H/sup 0/ excited states produced by foil stripping of 800-MeV H/sup -/ ions

Foil stripping of H/sup -/ directly to H/sup +/ is being considered for proton injection in the next generation of high-current proton storage rings. This technique can result in significant losses because excited states of H/sup 0/, which are also produced in the foil, are field stripped in the downstream bending magnets. Without due care in the injection system design, many of the resulting protons will be outside the acceptance of the storage ring and will be quickly lost. We measured the production of such H/sup 0/ excited states at the LAMPF High Resolution Atomic Beam Facility. An 800-MeV H/sup -/ beam was passed through carbon foils of thicknesses 70, 100, 200, and 300 /spl mu/g/cm/sup 2/ and the excited states were analyzed by a special magnet downstream of the foil. The magnet had a linear field gradient so that the trajectories of the outgoing protons could be used to reconstruct the field values at which the various H/sup 0/ stripped. We found that about 1% of the H/sup 0/ emerge in excited states which can be stripped to protons by ring-bending magnets.<<ETX>>

Operation of the optically pumped polarized H - ion source at LAMPF

A report is presented on the first five months of operation of the Optically Pumped Polarized Ion Source (OPPlS) for the nuclear physics research program at Los Alamos Meson Physics Facility (LAMPF). The LAMPF OPPIS is unique in using Ti:Sapphire lasers to polarize the potassium charge-exchange medium, and until recently was unique in using a superconducting magnet in the electron cyclotron resonance (ECR) source and polarizer regions. The ECR extraction electrode biasing arrangement is also unique. Typical performance was 25 mu A of peak current (measured at 750 keV) with 55% beam polarization or 15 mu A at 62%. Ion source availability was greater than 90%. Also reported on are planned improvements in preparation for research operation in May of 1991.<<ETX>>

Polarization observables for the reaction pp→ppπ0 at 800 MeV

Abstract The Wolfenstein polarization observables DNN, D SΩ and D LΩ , where Ω denotes a mixture of S and L polarization components, the induced polarization P, and the analysing power A have been measured for the reaction pp→ppπ0 at 800, 733, and 647 MeV. Comparisons are made to theoretical predictions of the model of Dubach, Kloet and Silbar.

Wide Dynamic Range Beam Profile Monitor

An economical harp multiplexer system has been developed to achieve a wide dynamic range. The harp system incorporates a pneumatically actuated harp detector with ceramic boards and carbon wires; a high-sensitivity multiplexer packaged in a double-wide NIM module; and flat, shielded ribbon cable consisting of individual twisted pairs. The system multiplexes 30 wires in each of the x and y planes simultaneously and operates with or without computer control. The system has operated in beams of 100 nA to 1 mA, 1-to 120-Hz repetition rate, with a signal-to-noise ratio of greater than 10/1.

Optical pumping of the polarized H - ion source at LAMPF

A report is presented on experiments to understand the laser optical pumping efficiency for the Optically Pumped Polarized Ion Source (OPPIS) at LAMPF. Measurements were made of ion beam polarization and current vs. laser power and potassium vapor thickness in order to understand the dependence of source performance on laser power and other parameters. Attempts to fit the data with simple scaling models to evaluate projected performance improvements are shown. The development of economical ways to make more efficient use of available laser power is described.<<ETX>>

LAMPF Primary Beam Line Protection System

An effective system for the protection of LAMPF primary beam lines has been built and installed. In three years of operations, it has prevented major damage from the effects of very high intensity (up to 600 ¿A) errant beams. The harsh environment of the target cells poses a major technical problem requiring the design of highly radiation hardened, remotely serviceable components capable of handling high thermal loads often in vacuum. After a brief discussion of general system considerations, the five major subsystems are described including design criteria, special problems encountered in implementation, operational effectiveness and planned improvements.

Measurement of DNN, DSS, DLS in pp → pp at 800 MeV

The spin transfer parameters DNN, DSS, DLS have been measured for pp elastic scattering at 800 MeV between 20° and 135° cm. These data bring the number of parameters measured at this energy to a total of 10, which is in general sufficient to determine a set of I=1 amplitudes.