H.E. Wegner

Supercollimation of Negative Ion Beams with Apertures

A technique for producing highly collimated beams of negative ions using apertures is discussed. The application of the method produced a 30 μ diam H− beam with an angular divergence of 1.5 mdeg. The results of a study of the small angle scattering of protons from a carbon are presented. Other possible applications are outlined.

Tandem injected relativistic heavy ion facility at Brookhaven, present and future

Abstract The Brookhaven Tandem Facility has recently been joined to the Alternating Gradient Synchrotron (AGS) by means of an ∼ 680 in long heavy ion transfer line. The design and construction of this line are described as well as the tandem and AGS modifications which made it possible to initiate a relativistic heavy ion research program. Operational experience and performance during the first 14.6 GeV/amu 16 O and 28 Si runs are reviewed. At present the facility is capable of accelerating ions up to mass ∼ 32. Future developments are described which will lead to the acceleration of heavier ions up to gold, and hopefully to the construction of a relativistic heavy ion collider for the entire mass range at center of mass energies up to 250 GeV per nucleon pair.

Charge changing cross sections of relativistic uranium

We report equilibrium charge state distributions of uranium at energies of 962 MeV/nucleon, 437 MeV/nucleon and 200 MeV/nucleon in low Z and high Z targets and the cross sections for U/sup 92 +/ reversible U/sup 91 +/ and U/sup 91 +/ reversible U/sup 90 +/ at 962 MeV/nucleon and 437 MeV/nucleon. Equilibrium thickness Cu targets produce approx. = 5% bare U/sup 92 +/ at 200 MeV/nucleon and 85% U/sup 92 +/ at 962 MeV/nucleon. 7 references, 5 figures.

Comparative Performance Study of Heavy Ion Injector Systems for High Energy Synchrotrons

Abstract The increased particle current demands on both ion source and injection facility by a heavy-ion synchrotron collider are analyzed. Also, the existing injector arrangement and performance for most of the worlds fixed-target heavy-ion synchrotrons are compared. At the present time, the Drookhaven relativistic heavy-ion collider (RHIC) requirements for the heaviest ions can be met by an injector with a front end consisting of a negative ion source and electrostatic tandem Van de Graaff accelerator. For the heaviest ions, considerable research and development is necessary on both ECR and EBIS high-charge state ion sources before required particle currents can be met.

A phoswich array for relativistic heavy ion collisions

Abstract A phoswich array consisting of 42 ΔE − E scintillator telescopes is described. The array was used for the measurement of charged pions, protons, deuterons and tritons produced near target rapidity in relativistic collisions of 14.6 A GeV/ c 28 Si nuclei with targets ranging in mass from aluminum to gold. The present paper describes the array, its operation and performance, its response to protons, deuterons and tritons, and the means by which the detector has been calibrated. Intrinsic energy resolutions on the order of 2–3% have been obtained.

Multiple ionization and capture in relativistic heavy-ion atom collisions

Abstract We show that in relativistic heavy-ion collisions the independent electron model can be used to predict cross sections for multiple inner-shell ionization and capture in a single collision. Charge distributions of 82- to 200-MeV/amu Xe and 105- to 955-MeV/amu U ion beams emerging from thin solid targets were used to obtain single- and multiple-electron stripping and capture cross sections. The probabilities of stripping electrons from the K, L, or M shells were calculated using the semiclassical approximation and Dirac hydrogenic wave functions. For capture, a simplified model for electron capture was used. The data generally agree with theory.