  "Neutron Optics and Physics (NOP/ BL05)" at MLF in J-PARC is a beamline for
studies of fundamental physics. The beamline is divided into three branches so
that different experiments can be performed in parallel. These beam branches
are being used to develop a variety of new projects. We are developing an
experimental project to measure the neutron lifetime with total uncertainty of
1 s (0.1%). The neutron lifetime is an important parameter in elementary
particle and astrophysics. Thus far, the neutron lifetime has been measured by
several groups; however, different values are obtained from different
measurement methods. This experiment is using a method with different sources
of systematic uncertainty than measurements conducted to date. We are also
developing a source of pulsed ultra-cold neutrons (UCNs) produced from a
Doppler shifter are available at the unpolarized beam branch. We are developing
a time focusing device for UCNs, a so called "rebuncher", which can increase
UCN density from a pulsed UCN source. At the low divergence beam branch, an
experiment to search an unknown intermediate force with nanometer range is
performed by measuring the angular dependence of neutron scattering by noble
gases. Finally the beamline is also used for the research and development of
optical elements and detectors. For example, a position sensitive neutron
detector that uses emulsion to achieve sub-micrometer resolution is currently
under development. We have succeeded in detecting cold and ultra-cold neutrons
using the emulsion detector.
