Speaker
Description
In order to improve the non- Standard Model weak interaction scalar and tensor coupling upper limits by an order of magnitude and to determine the helicity of an antineutrino combined with a low velocity charged lepton, the free neutron bound beta decay (n → H + ) (BOB) shall be measured. Thereby, monoenergetic metastable BOB H atoms (T=~326 eV) with a single hyperfine state, selected by a spin filter, generated at the center of a high flux beam reactor throughgoing beam tube (for example at the PIK reactor, Gatchina), are transformed with high efficiency (> 10%) into H- ions within an Argon cell. After extraction from the beam tube by means of a pulsed electric deflector, the H- are measured by a velocity filter based on the Bradbury Nielsen Gate technology and an MCP detector. Although the bound beta decay branching ratio is small (4·10-6), the experiment seams feasible. Necessary experimental components, as a Bradbury Nielsen (BN) gate velocity filter, a pulsed electric deflector and an electrical quadrupole doublet have been developed, built and tested using low energy proton and oxygen beams. As an application for the BN gate chopper, the secondary electron yield from protons passing thin carbon foils has been measured.
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