Solid Angle Acceptance Research Articles

Ion Microprobe Mass Analyzer

This paper describes the development of an instrument which is analogous to an electron microprobe x-ray analyzer, whereby the electron microprobe is replaced by an ion microprobe, and the x-ray spectrometer by a mass spectrometer. A duoplasmatron is the primary ion source. The primary ion beam is mass separated to eliminate impurity ions. A probe diameter of less than 2 μ at 2×10−10 A is realized for 12-kV Ar+ ions. A new mass spectrometer was developed with the emphasis on high transmission, yet simple construction. It is stigmatic imaging, double focusing, has a mass-resolving power of 300 with a solid acceptance angle of 1.5×10−2 sr (4° half-angle) and a transmitted-energy bandwidth of 10%. It consists of an axially symmetrical electrostatic Einzel lens, a 45° spherical condenser sector, and a magnetic field with plane but inclined pole faces, which deflects the beam by 90°. No entrance slit is used. Experimental results are presented.

Design and Performance of a High Momentum, High Luminosity Spectrometer for Particle Analysis

A 90° bend n=0 magnetic spectrometer has been constructed which uses curved field boundaries to achieve second order correction of the focal properties and to make the image plane normal to the emerging particles. The spectrometer has a 112 cm radius of curvature and a maximum momentum capability of 725 MeV/c. The window frame yoke, with sloping edge profiles to minimize edge saturation, enables the focal properties to remain invariant up to 21 kG. The solid angle acceptance is 8×10−3 sr with 0.1% resolution and the maximum momentum acceptance is ±5%.

Semigraphical Solution of Focusing and Transmission of Quadrupole Lens Systems

A semigraphical method is presented for evaluating the focusing conditions and the acceptance solid angle of quadrupole lens systems. The method is illustrated for a specific triplet magnetic quadrupole system for which the predictions are confirmed experimentally.

Magnetic Lens System of Unit Magnification for High Energy Charged Particles

A magnetic lens system designed from studies made with computing machines has been built and used at the Brookhaven cosmotron. It collected pions of 1020 MeV/c mean momentum produced at a target in the external proton beam, selected a narrow momentum bandwidth from a continuous momentum spectrum, recombined the selected momenta, and refocused the pions to an image of unit magnification. The effective solid angle of acceptance was 5.04×10−3 sr and the momentum band pass width was ±30 MeV/c. The measured particle yield on 1 in.2 at the focus was 5×105 for 6×1010 internal 3BeV/c protons; 27% were positive pions and 73% were protons.

A magnetic particle spectrometer for use with a 12 MeV tandem electrostatic generator

A new double-focussing magnetic particle spectrometer, with a solid angle of acceptance of 0.007 steradians is described. The resolving power in energy is 850 for protons of up to 12 MeV; saturation effects lower this figure to 450 for protons of energy 21 MeV. Use of the spectrometer, both for measuring the yields of nuclear reactions, and as a tool for investigating the gamma decay modes of selected nuclear levels, is discussed.

A Magnetic Analyzer for Charged-Particles from Nuclear Reactions

A double-focusing magnetic spectrometer for detecting and analyzing charged particles from nuclear reactions is described. The magnetic field, varying as r−½ near an average radius of 10.5 in., extends over a semicircle yielding object and anastigmatic image positions some distance outside of the region of strong field. The acceptance solid angle is Ω=0.0061 sterad. and the momentum resolution with an 8-mm slit at the detector is R=128. The ultimate resolution determined by spherical aberration and some residual astigmatism is about 1000. Applications to the study of the energy and yield of nuclear reaction products are discussed.