Problems associated with the production of monoenergetic neutrons using the NPL 3.5 MV van de Graaf accelerator and their solution
Abstract
Contamination of either the accelerator and the associated beam-line system or the neutron-producing target in van de Graaff generators are discussed, and examples determined using the time-of-flight technique are presented. Recommendations which minimize and stabilize the contributions to the overall neutron field due to neutrons produced by ion-beam interactions with these contaminants are made. A method for eliminating these effects based upon the use of two identical, or nearly identical target disks, a foreground one containing the primary target material and a background one containing none of this material is described. To normalize measurements obtained with the two targets to each other prior to subtraction, a current integrator is used as a monitor. Recommendations which maintain the neutron yield per microcoulomb of incident ion-beam current stable in the short and the long term are presented. Examples of the stability that can be achieved are given, together with background corrected time-of-flight data which demonstrate the usefulness of the methods and recommendations.
- Publication:
-
Unknown
- Pub Date:
- December 1986
- Bibcode:
- 1986papm.rept.....H
- Keywords:
-
- Neutron Beams;
- Neutron Emission;
- Neutron Physics;
- Van De Graaff Accelerators;
- Experiment Design;
- Particle Accelerator Targets;
- Time Of Flight Spectrometers;
- Atomic and Molecular Physics