Physics of Fundamental Symmetries and Interactions-PSI2010 Neutron Bound β-Decay-BOB

The bound neutron β-decay(BOB) into a hydrogen atom and an electron antineutrino is investigated. The hyperfinestate population of the monoenergetic hydrogen atoms yields the neutrino left-handedness or a possible right-handed admixture and possible small scalar and tensor contributions to the weak force. The BOB H(2s) hyperfine states are separated with a Lamb shift spin filter. The H(2s) atoms are detected either by quenching yielding Lyman-α photons, or ionizing or charge exchanging into protons and H − , respectively. A first experiment is planned at the FRM2 high thermal neutron flux beam reactor SR6 through-going beam pipe. The neutron and γ ray background suppression with absorbing traps between SR6 and the experiment has been simulated using MCNP4 and GEANT4. The Lyman-α photon background produced by protons hitting the vacuum chamber wall was measured in a mockup setup.