1,059 research outputs found
Statistical Uncertainty in Quantitative Neutron Radiography
We demonstrate a novel procedure to calibrate neutron detection systems
commonly used in standard neutron radiography. This calibration allows
determining the uncertainties due to Poisson-like neutron counting statistics
for each individual pixel of a radiographic image. The obtained statistical
errors are necessary in order to perform a correct quantitative analysis. This
fast and convenient method is applied to data measured at the cold neutron
radiography facility ICON at the Paul Scherrer Institute. Moreover, from the
results the effective neutron flux at the beam line is determined
Spatial confinement of muonium atoms
We report the achievement of spatial confinement of muonium atoms (the bound
state of a positive muon and an electron). Muonium emitted into vacuum from
mesoporous silica reflects between two SiO confining surfaces separated by
1 mm. From the data, one can extract that the reflection probability on the
confining surfaces kept at 100 K is about 90% and the reflection process is
well described by a cosine law. This technique enables new experiments with
this exotic atomic system and is a very important step towards a measurement of
the 1S-2S transition frequency using continuous wave laser spectroscopy.Comment: 5 pages, 6 figure
Inequalities for nucleon generalized parton distributions with helicity flip
Several positivity bounds are derived for generalized parton distributions
(GPDs) with helicity flip.Comment: 20 page
Measurement of the Michel Parameter xi" in Polarized Muon Decay and Implications on Exotic Couplings of the Leptonic Weak Interaction
The Michel parameter xi" has been determined from a measurement of the
longitudinal polarization of positrons emitted in the decay of polarized and
depolarized muons. The result, xi" = 0.981 +- 0.045stat +- 0.003syst, is
consistent with the Standard Model prediction of unity, and provides an order
of magnitude improvement in the relative precision of this parameter. This
value sets new constraints on exotic couplings beyond the dominant V-A
description of the leptonic weak interaction.Comment: 15 pages, 16 figures, 3 tables; submitted to Phys. Rev.
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