57 research outputs found
A boron-coated CCD camera for direct detection of Ultracold Neutrons (UCN)
A new boron-coated CCD camera is described for direct detection of ultracold
neutrons (UCN) through the capture reactions B
(n,0)Li (6%) and B(n,1)Li (94%).
The experiments, which extend earlier works using a boron-coated ZnS:Ag
scintillator, are based on direct detections of the neutron-capture byproducts
in silicon. The high position resolution, energy resolution and particle ID
performance of a scientific CCD allows for observation and identification of
all the byproducts , Li and (electron recoils). A
signal-to-noise improvement on the order of 10 over the indirect method has
been achieved. Sub-pixel position resolution of a few microns is demonstrated.
The technology can also be used to build UCN detectors with an area on the
order of 1 m. The combination of micrometer scale spatial resolution, few
electrons ionization thresholds and large area paves the way to new research
avenues including quantum physics of UCN and high-resolution neutron imaging
and spectroscopy.Comment: 10 pages, 8 figure
Status of the UCNÏ„ experiment
The neutron is the simplest nuclear system that can be used to probe the structure of the weak interaction and search for physics beyond the standard model. Measurements of neutron lifetime and β-decay correlation coefficients with precisions of 0.02% and 0.1%, respectively, would allow for stringent constraints on new physics. The UCNτ experiment uses an asymmetric magneto-gravitational UCN trap with in situ counting of surviving neutrons to measure the neutron lifetime, τ_n = 877.7s (0.7s)_(stat) (+0.4/−0.2s)_(sys). We discuss the recent result from UCNτ, the status of ongoing data collection and analysis, and the path toward a 0.25 s measurement of the neutron lifetime with UCNτ
A multilayer surface detector for ultracold neutrons
A multilayer surface detector for ultracold neutrons (UCNs) is described. The
top B layer is exposed to the vacuum chamber and directly captures UCNs.
The ZnS:Ag layer beneath the B layer is a few microns thick, which is
sufficient to detect the charged particles from the B(n,)Li
neutron-capture reaction, while thin enough so that ample light due to
and Li escapes for detection by photomultiplier tubes. One-hundred-nm thick
B layer gives high UCN detection efficiency, as determined by the mean
UCN kinetic energy, detector materials and others. Low background, including
negligible sensitivity to ambient neutrons, has also been verified through
pulse-shape analysis and comparisons with other existing He and B
detectors. This type of detector has been configured in different ways for UCN
flux monitoring, development of UCN guides and neutron lifetime research.Comment: 21 pages, 10 figure
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