A Mott polarimeter for the search of time reversal violation in the decay of free neutrons

Lorentz invariance violation in weak interaction: search for effects in beta decay of polarized neutrons

“…Being governed by the electromagnetic interactions such modulations are constrained much more stringently in other experiments. The first two effects were studied in the past in the performance tests of the experimental apparatus [11,12] and have been estimated to η ≈ 0.0012 and ε ≈ 0.005, respectively. The asymmetry of the average efficiencies of the lower and upper detector parts was calculated directly from the data: λ ≈ 0.05.…”

“…Detailed description of the design, operation and performance of the detection system can be found in Ref. [11]. The acquired experimental data contain about 3 × 10 8 electrons with fully reconstructed momenta, collected during a period of three months of data taking.…”

Readout System for Medium-Size Experiments

“…This solution is reasonably simple but very reliable method for medium-sized experiments to upgrade and expand their readout electronics without major hardware investments. The Full FERA system has been successfully implemented in a number of recent precision experiments, in some of which the configuration has been extended to include also the generic PCOS III readout system of multi-wire proportional chambers (Barnet et al 2000;Ban et al 2006;Stephan et al 2007;Stephan et al 2009). The FERA system gains on capabilities due to now available modules, like Ortec Histogramming Memory HM413, CMCamac Driver, Memory and Histogrammer CMC203 or Wiener CAMAC-to-FERA Bridge.…”

Measurement of the Transverse Polarization of Electrons Emitted in Free Neutron Decay

“…This allowed for efficient use of one of the world strongest polarized, cold neutron beams as a source of electrons from neutron decay and for application of efficient electron polarimetry based on Mott-backscattering [32]. An additional advantage of this principle is the unique signature of relatively rare Mott scattering events which made them easily distinguishable off-but also on-line from an overwhelming background of electrons accompanying this, very strong, neutron beam.…”

“…This allows scaling the "off beam" background distribu- tion such that it matches the high energy part of the "from beam" energy spectrum. For this assumption to hold, the "off beam" range has to be carefully chosen for both: the inclination angle and the extrapolated origin of the tracks at the opposite detector side [32]. These conditions have to account for the angular resolution of the MWPC, the beam density distribution and its divergence.…”