M. Daum

Test of Lorentz invariance with spin precession of ultracold neutrons

A clock comparison experiment, analyzing the ratio of spin precession frequencies of stored ultracold neutrons and 199Hg atoms, is reported. No daily variation of this ratio could be found, from which is set an upper limit on the Lorentz invariance violating cosmic anisotropy field b perpendicular < 2 x 10(-20) eV (95% C.L.). This is the first limit for the free neutron. This result is also interpreted as a direct limit on the gravitational dipole moment of the neutron |gn| < 0.3 eV/c2 m from a spin-dependent interaction with the Sun. Analyzing the gravitational interaction with the Earth, based on previous data, yields a more stringent limit |gn| < 3 x 10(-4) eV/c2 m.

Towards a new measurement of the neutron electric dipole moment

The effort towards a new measurement of the neutron electric dipole moment (nEDM) at the Paul Scherrer Instituts (PSI) new high intensity source of ultracold neutrons (UCN) is described. The experimental technique relies on Ramseys method of separated oscillatory fields, using UCN in vacuum with the apparatus at ambient temperature. In the first phase, R&D towards the upgrade of the RAL/Sussex/ILL apparatus is being performed at the Institut Laue-Langevin (ILL). In the second phase the apparatus, moved from ILL to PSI, will allow an improvement in experimental sensitivity by a factor of 5. In the third phase, a new spectrometer should gain another order of magnitude in sensitivity. The improvements will be mainly due to (1) much higher UCN intensity, (2) improved magnetometry and magnetic field control, and (3) a double chamber configuration with opposite electric field directions.

Spin-dependent neutron-proton total cross section differences ΔσL and ΔσT from 140 to 590 MeV

Abstract A polarized neutron beam at PSI has been used to measure the spin-dependent neutron-proton total cross sections Δσ L and Δσ T from 140 to 590 MeV. The results are compared with recent phase-shift calculations.

Analysing power for the reaction \(\mathrm{np} \rightarrow \mathrm{pp} \pi^{-}\) and for np elastic scattering from 270 to 570 MeV

Abstract. The analysing power of the reaction

Observation of Gravitationally Induced Vertical Striation of Polarized Ultracold Neutrons by Spin-Echo Spectroscopy

{\rm n} {\rm p} \rightarrow {\rm p} {\rm p} \pi^{-}

Production of ultracold neutrons from cryogenic 2H2, O2, and C2H4 converters

for neutron energies between threshold and 570 MeV has been determined using a transversely polarised neutron beam at PSI. The reaction has been studied in a kinematically complete measurement using a time-of-flight spectrometer with large acceptance. Analysing powers have been determined as a function of the c.m. pion angle in different regions of the proton-proton invariant mass. They are compared to other data from the reactions

A prestorage method to measure neutron transmission of ultracold neutron guides

{\rm n} {\rm p} \rightarrow {\rm p} {\rm p} \pi^{-}

Search for Axionlike Dark Matter through Nuclear Spin Precession in Electric and Magnetic Fields

and

Investigation of Solid D 2 for UCN Sources

{{\rm p} {\rm p} \rightarrow {\rm p} {\rm p} \pi^{0}}

Measurements of the total cross section differences ΔσL(np) and ΔσT(np) in the energy range from 140 to 590 MeV

. The np elastic scattering analysing power was determined as a by-product of the measurements.