Axion Dark Matter Search around 4.55 µeV with Dine-Fischler-Srednicki-Zhitnitskii Sensitivity.

We report an axion dark matter search at Dine-Fischler-Srednicki-Zhitnitskii sensitivity with the CAPP-12TB haloscope, assuming axions contribute 100% of the local dark matter density. The search excluded the axion-photon coupling g_{aγγ} down to about 6.2×10^{-16} GeV^{-1} over the axion mass range between 4.51 and 4.59 µeV at a 90% confidence level. The achieved experimental sensitivity can also exclude Kim-Shifman-Vainshtein-Zakharov axion dark matter that makes up just 13% of the local dark matter density. The CAPP-12TB haloscope will continue the search over a wide range of axion masses.

First Results from an Axion Haloscope at CAPP around 10.7 µeV.

The Center for Axion and Precision Physics Research at the Institute for Basic Science is searching for axion dark matter using ultralow temperature microwave resonators. We report the exclusion of the axion mass range 10.7126-10.7186 µeV with near Kim-Shifman-Vainshtein-Zakharov (KSVZ) coupling sensitivity and the range 10.16-11.37 µeV with about 9 times larger coupling at 90% confidence level. This is the first axion search result in these ranges. It is also the first with a resonator physical temperature of less than 40 mK.

Luminescence and spectral hole burning of Sm(2+) doped in Li(2)O-SrO-B(2)O(3) glass-ceramics.

The Sm(3+)-doped alkali strontium borate glass-ceramics were obtained by heating of the as-made glasses in air, where Sm(3+) ions were reduced to Sm(2+) ions. The XRD, optical absorption spectra and luminescence of Sm(3+) and Sm(2+) ions were investigated. The excitation spectra of the (7)F(0)-->(5)D(0) transition were measured in the region of (7)F(0)-->(5)D(1) transition, where spectral holes were burnt within two of the Stark split (5)D(1) bands. The Sm(2+) ions doped glass ceramics exhibit the persistent spectral hole burning at room temperature. The hole depth, which are burned by the DCM dye laser, are about 40% of the total intensity, respectively. It is concluded that the dominant burning mechanism is a photoionization of electron trapping at a site other than Sm(3+) ions because of the absence of an antihole around the burned hole.

Development of position sensitive radiation detectors using gas electron multipliers.

Gas electron multipliers (GEM) were introduced to develop a radiation detector which is applicable to medical imaging or luggage inspection systems at the airport or harbor. Two GEM foils were used in the amplifier, and an Ar/CO(2) mixed gas was inserted into the chamber at a mixing ratio of Ar:CO(2)=80:20. A two-dimensional X-ray image was taken with a 64-channel GEM detector from an Fe-55 radiation source. We also constructed a 256-channel GEM detector in which 4 charge sensitive preamplifiers were used in a daisy chain. With linear array type readout electrodes, we were able to realize a position sensitive radiation detector.