J.A. Jungerman

A medium-energy neutron facility

Abstract This paper describes a facility for producing variable energy neutron beams in the energy range 20 to 60 MeV using protons from the 76″ Isochronous Cyclotron at the University of California, Davis. The 7 Li(p, n) 7 Be reaction is used to produce nearly monoenergetic beams with approximately 60% of the neutrons in a well defined peak.

Production of medium-energy neutrons from proton bombardment of light elements☆

Abstract Cross sections for neutron production from targets of 2 H, 6 Li, 7 Li, 9 Be, 12 C and 27 Al have been measured at 0° for incident proton energies of approximately 30, 40 and 50 MeV. For production of a monoenergetic neutron beam in this energy region 7 Li is the best practical target. 12 C has a low neutron production cross section and is particularly useful for proton beam collimation.

Detection efficiency of a plastic scintillator for 20 to 170 MeV neutrons

Abstract The neutron detection efficiency of a plastic scintillator 30.5 cm long and 12.7 cm in dia. has been measured for neutron energies from about 10–70 MeV. These were obtained by scattering a 193 MeV neutron beam from a liquid hydrogen target. A telescope selected protons from the n-p scattering which then determined the energy and flux of neutrons in the conjugate solid angle. A known fraction of this flux was intercepted by the neutron detector and the efficiency was thus determined. For an electron threshold near 1 MeV the efficiency is nearly constant from 20–50 MeV, then it decreases slowly with increasing neutron energy. As expected thresholds two and four times larger decrease the efficiency, particularly at low energy.

Production of medium-energy neutrons from proton bombardment of light elements using revised neutron-proton differential cross sections

Abstract Previously measured (p,n) reactions at 0° on 2 H, 6 Li, 7 Li, 9 Be, 12 C and 27 Al at incident energies of approximately 30, 40 and 50 MeV have been revised using recent n-p differential cross section parametrizations. The new values show an improved overall agreement with those reported elsewhere.

A precision solenoidal beta ray spectrometer

Abstract The design and performance of a solenoidal type beta ray spectrometer is discussed. The uniform (1 in 104) magnetic field is measured and controlled by nuclear magnetic resonance of the proton. A mean take-off angle of 23.50 is employed with a scale factor D = 2 p/eB = 78.8 cm . Absolute Bϱ values are given for the E, F. I, J, L, O, P, and X lines of ThB active deposit. Resolution and transmission observed are compared with theoretical values. At resolutions of 0.050%, 0.047%, 0.028%, and 0.018%, the measured transmissions are 0.36%, 0.32% 0.11%, and 0.040% for the I line of ThB.

Fourth‐order uniform electric field from two charged rings

It is shown that an electric field uniform to fourth order can be formed by using two charged rings of equal radii separated by √6 times the ring radius. Calculations of the field distribution and the deviation from uniformity are made. The axial and radial electric fields are calculated using an expansion valid near the origin of coordinates and, more generally, by evaluation of elliptic integrals.

Production of a Uniform Magnetic Field by Means of an End‐Corrected Solenoid

Calculations and experimental technique used in producing a uniform magnetic field with an end‐corrected solenoid are discussed. The field was trimmed to be uniform to 0.01% in an axial region comprising 63% of the solenoid at a maximum field strength of 480 gauss.

A preliminary report on the 22-inch spiral ridge cyclotron at the University of California, Davis†

General features of the University of California, Davis 22-inch spiral ridge cyclotron are discussed. The accelerator has a C-magnet with a vertical gap. It is designed for service with continuous variation in particle energy using a maximum average magnetic field of 20 kilogauss. Protons can be accelerated to 12 MeV by means of a two dee radiofrequency system. In phase mode operation is planned for acceleration of deuterons and alpha-particles.

Monte Carlo calculation of d-Be neutron yields

Abstract A Monte Carlo program is described that calculates the neutron intensity from the bombardment of thick beryllium targets with deuterons of energies from 14 to 40 MeV. Calculations give neutron intensities off the deuteron beam axis as well as as on-axis. Comparisons are made with experimental thick-target yields.

Solenoid Pair for Production of a Seventh‐Order External Field

The magnetic field is calculated for a coaxial pair of solenoids having an external axial field which decreases as the inverse seventh power of the distance from the solenoid centers. The effect of finite coil thickness is discussed.