The lifetime of the neutron is one of the key physical quantities used to determine the weak interaction parameters and to test predictions of the theory of primary nucleosynthesis. The lifetime of ...the neutron has been measured in the reported experiment by the method of storing neutrons in a material trap with a gravitational valve. Fomblin grease UT-18 hydrogen-free fluorine polymer has been used as coating. The resistance of the coating to repeated cooling down to 80 K combined with heating up to 300 K has been studied. The probability of losses in the trap is as small as 1.5% of the neutron decay probability. The lifetime of the neutron τ
n
= (881.5 ± 0.7
stat
± 0.6
syst
)s obtained at the new step is in good agreement with a commonly accepted value of (880.2 ± 1.0) s presented by the Particle Data Group.
A new measurement of the neutron lifetime, carried out with the aid of a large gravitational spectrometer made in Petersburg Institute of Nuclear Physics (PNPI) is presented: τn = 881.5 ± 0.7 ± 0.6 ...s. In our experiment the measurement of neutron lifetime is carried out using the method of storing ultracold neutrons in a material trap with gravitational barrier. Further improvement of the obtained result can be achieved at the helium temperatures. Here we present our neutron lifetime result, modified installation scheme and the first results of cryogenic tests are discussed.
Ultracold-neutron infrastructure for the PNPI/ILL neutron EDM experiment Serebrov, A.P.; Geltenbort, P.; Shoka, I.V. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
12/2009, Letnik:
611, Številka:
2
Journal Article
Recenzirano
A PNPI/ILL experiment to measure the neutron electric dipole moment (EDM) is currently being prepared at the facility PF2 for ultracold neutrons (UCN) at the Institut Laue-Langevin in Grenoble. To ...enable an improvement of sensitivity, one of PF2's beam positions has been equipped with new components for UCN transport, polarization and beam characterization, comprised of a superconducting solenoid-polarizer with magnetic field 4
T, a neutron guide system with diameter 136
mm prepared in replica technology, and a novel beam chopper for time-of-flight analysis. The whole EDM apparatus is set up on a non-magnetic platform. The total flux of polarized UCN with velocities less than 6.8
m/s along the guide axis is 1.5×10
5
n/s, corresponding to a flux density of 10
3
cm
−2
s
−1. The density of polarized UCN at the experimental position is about 5
cm
−3, which shall lead to an EDM measurement with a counting statistical accuracy of 1.5×10
−26
ecm during 200 days of operation at PF2.
Currently the most accurate measurements of neutron lifetime are being performed at the Petersburg Nuclear Physics Institute with ultracold neutrons (UCNs) stored in a gravitational trap. A modified ...setup with a large gravitational trap and cooling to 10–15 K is presented. The results of measurements of temperature dependence of UCN losses in collisions with walls, which were coated with a perfluorinated grease (Fomblin UT 18), at 300–77 K, are detailed. The probable heat inflow to the trap is estimated, and the feasibility of cooling to indicated temperatures in experiments with the modified setup is demonstrated.
We report a new measurement of the neutron electric dipole moment with the PNPI EDM spectrometer using the ultracold neutron source PF2 at the research reactor of the ILL. Its first results can be ...interpreted as a limit on the neutron electric dipole moment of |
d
n
| < 5.5 × 10
−26
e cm (90% confidence level).
A research program aimed at studying fundamental interactions by means of ultracold and polarized cold neutrons at the GEK-4-4′ channel of the PIK reactor is presented. The apparatus to be used ...includes a source of cold neutrons in the heavy-water reflector of the reactor, a source of ultracold neutrons based on superfluid helium and installed in a cold-neutron beam extracted from the GEK-4 channel, and a number of experimental facilities in neutron beams. An experiment devoted to searches for the neutron electric dipole moment and an experiment aimed at a measurement the neutron lifetime with the aid of a large gravitational trap are planned to be performed in a beam of ultracold neutrons. An experiment devoted to measuring neutron-decay asymmetries with the aid of a superconducting solenoid is planned in a beam of cold polarized neutrons from the GEK-4′ channel. The second ultracold-neutron source and an experiment aimed at measuring the neutron lifetime with the aid of a magnetic trap are planned in the neutron-guide system of the GEK-3 channel. In the realms of neutrino physics, an experiment intended for sterile-neutrino searches is designed. The state of affairs around the preparation of the experimental equipment for this program is discussed.
In this work, the double chamber magnetic resonance spectrometer of the Petersburg Nuclear Physics Institute (PNPI) designed to measure the neutron electric dipole moment (EDM) is briefly described. ...A method for long storage of polarized ultracold neutrons in a resonance space with a superposed electric field collinear to the leading magnetic field is used. The results of the measurements carried out on the ILL reactor (Grenoble, France) are interpreted as the upper limit of the value of neutron EDM |d
n
| < 5.5 × 10
–26
e
cm at the 90% confidence level.
The paper reports the results of an experiment on searching for the neutron electric dipole moment (EDM), performed on the ILL reactor (Grenoble, France). The double-chamber magnetic resonance ...spectrometer (Petersburg Nuclear Physics Institute (PNPI)) with prolonged holding of ultra cold neutrons has been used. Sources of possible systematic errors are analyzed, and their influence on the measurement results is estimated. The ways and prospects of increasing accuracy of the experiment are discussed.
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