31 research outputs found
New experimental limits on neutron - mirror neutron oscillations in the presence of mirror magnetic field
Present probes do not exclude that the neutron () oscillation into mirror
neutron (), a sterile state exactly degenerate in mass with the neutron,
can be a very fast process, in fact faster than the neutron decay itself. This
process is sensitive to the magnetic field. Namely, if the mirror magnetic
field exists at the Earth, oscillation probability can be
suppressed or resonantly amplified by the applied magnetic field ,
depending on its strength and on the angle between and
. We present the results of ultra-cold neutron storage measurements
aiming to check the anomalies observed in previous experiments which could be a
signal for oscillation in the presence of mirror magnetic field ~G. Analyzing the experimental data on neutron loses, we obtain a new lower
limit on oscillation time s (95 % C.L.) for any
between 0.08 and 0.17 G, and s (95 % C.L.)
for any in the interval () G
Neutron lifetime measurements using gravitationally trapped ultracold neutrons
Our experiment using gravitationally trapped ultracold neutrons (UCN) to
measure the neutron lifetime is reviewed. Ultracold neutrons were trapped in a
material bottle covered with perfluoropolyether. The neutron lifetime was
deduced from comparison of UCN losses in the traps with different
surface-to-volume ratios. The precise value of the neutron lifetime is of
fundamental importance to particle physics and cosmology. In this experiment,
the UCN storage time is brought closer to the neutron lifetime than in any
experiments before:the probability of UCN losses from the trap was only 1% of
that for neutron beta decay. The neutron lifetime
obtained,878.5+/-0.7stat+/-0.3sys s, is the most accurate experimental
measurement to date.Comment: 38 pages, 19 figures,changed conten
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
New Neutron Lifetime Measurements with the Big Gravitational Trap and Review of Neutron Lifetime Data
Neutron lifetime is one of the most important physical constants which determines parameters of the weak interaction and predictions of primordial nucleosynthesis theory. In our experiment we measure the storage time of UCN in the material trap coated with a hydrogen-free fluorine-containing polymer (Fomblin grease UT-18). The stability of this coating to multiple thermal cycles between 80 K and 300 K was tested. The achieved storage time is only 1.5% less than free neutron lifetime. Using additional surface, which can be plunged into the trap to change the collision frequency of UCN with walls, we calculate free neutron lifetime by extrapolation to zero collision frequency. The result of the measurements with this new experimental setup i
Experimental search for long-range forces in neutron scattering via a gravitational spectrometer
© 2014 American Physical Society, https://dx.doi.org/10.1103/physrevc.89.044002In this work we introduce a method of measuring low-energy scattering cross section with a gravitational spectrometer. In this method we add atoms (i.e., He) to the gravitational spectrometer filled with a target gas of ultracold neutrons (UCN). We search for long-range forces between atoms and UCN by measuring transfer of a small recoil energy similar to 10(-7) eV using the gravitational spectrometer. As a result of this search we set new constraints on the strength of long-range forces within the range of the effective radius of interaction of 10(-7)-10(-4) cm.Russian Foundation for Basic Research (Projects No. 08-02-01052a, No. 10-02-00217a, and No. 10-02-00224a)Ministry of Education and Science of the Russian Federation (Contracts No. 02.740.11.0532 and No. 14.740.11.0083