1,324 research outputs found
Development of an electron density probe Final report, 22 Jun. 1964 - 22 Mar. 1965
Electron density probes to perform measurements in flow fields at high altitude
A solenoidal electron spectrometer for a precision measurement of the neutron -asymmetry with ultracold neutrons
We describe an electron spectrometer designed for a precision measurement of
the neutron -asymmetry with spin-polarized ultracold neutrons. The
spectrometer consists of a 1.0-Tesla solenoidal field with two identical
multiwire proportional chamber and plastic scintillator electron detector
packages situated within 0.6-Tesla field-expansion regions. Select results from
performance studies of the spectrometer with calibration sources are reported.Comment: 30 pages, 19 figures, 1 table, submitted to NIM
Measurement of the neutron lifetime using a gravitational trap and a low-temperature Fomblin coating
We present a new value for the neutron lifetime of 878.5 +- 0.7 stat. +- 0.3
syst. This result differs from the world average value (885.7 +- 0.8 s) by 6.5
standard deviations and by 5.6 standard deviations from the previous most
precise result. However, this new value for the neutron lifetime together with
a beta-asymmetry in neutron decay, Ao, of -0.1189(7) is in a good agreement
with the Standard Model.Comment: 11 pages, 9 figures; extended content with some correction
The influence of the chameleon field potential on transition frequencies of gravitationally bound quantum states of ultra-cold neutrons
We calculate the chameleon field potential for ultracold neutrons, bouncing
on top of one or between two neutron mirrors in the gravitational field of the
Earth. For the resulting non--linear equations of motion we give approximate
analytical solutions and compare them with exact numerical ones for which we
propose the analytical fit. The obtained solutions may be used for the
quantitative analysis of contributions of a chameleon field to the transition
frequencies of quantum states of ultra-cold neutrons bound in the gravitational
field of the Earth.Comment: 11 pages, 4 figure
Three channel model of meson-meson scattering and scalar meson spectroscopy
New solutions on the scalar -- isoscalar phase shifts are analysed
together with previous results using a separable potential model of
three coupled channels (, and an effective
system). Model parameters are fitted to two sets of solutions obtained in a
recent analysis of the CERN-Cracow-Munich measurements of the reaction on a polarized target. A relatively
narrow (90 -- 180 MeV) scalar resonance is found, in contrast
to a much broader ( MeV) state emerging from the analysis
of previous unpolarized target data.Comment: 10 Latex pages + 6 postscript figure
Measuring the proton spectrum in neutron decay - latest results with aSPECT
The retardation spectrometer aSPECT was built to measure the shape of the
proton spectrum in free neutron decay with high precision. This allows us to
determine the antineutrino electron angular correlation coefficient a. We aim
for a precision more than one order of magnitude better than the present best
value, which is Delta_a /a = 5%.
In a recent beam time performed at the Institut Laue-Langevin during April /
May 2008 we reached a statistical accuracy of about 2% per 24 hours measurement
time. Several systematic effects were investigated experimentally. We expect
the total relative uncertainty to be well below 5%.Comment: Accepted for publication in the Conference Proceedings of the
International Workshop on Particle Physics with Slow Neutrons 2008 held at
the ILL, France. To be published in Nuclear Instruments and Methods in
Physics Research, Section
eta, eta-prime -> pi^+ pi^- gamma with coupled channels
The decays eta, eta-prime -> pi^+ pi^- gamma are investigated within an
approach that combines one-loop chiral perturbation theory with a coupled
channel Bethe-Salpeter equation which satisfies unitarity constraints and
generates vector mesons dynamically from composite states of two pseudoscalar
mesons. It is furthermore shown that the inclusion of the eta-prime as a
dynamical degree of freedom does not renormalize the Wess-Zumino-Witten term.Comment: 21 pages, 11 figure
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