1,249 research outputs found
Tokyo Axion Helioscope
A new search result of the Tokyo axion helioscope is presented. The axion
helioscope consists of a dedicated cryogen-free 4T superconducting magnet with
an effective length of 2.3 m and PIN photodiodes as x-ray detectors. Solar
axions, if exist, would be converted into X-ray photons through the inverse
Primakoff process in the magnetic field. Conversion is coherently enhanced even
for massive axions by filling the conversion region with helium gas. The
present third phase measurement sets a new limit of
g_{a\gamma\gamma}<(5.6--13.4)\times10^{-10} GeV^{-1} for the axion mass of
0.84<m_a<1.0 eV at 95% confidence level.Comment: 4th Patras Workshop on Axions, WIMPs and WISP
Search for Hidden photons with Sumico
We searched for solar hidden photons in the visible photon energy range using
a hidden photon detector add-on attached to Sumico. It consists of a parabolic
mirror of dia. 0.5m and f=1m installed in a vacuum chamber, and a low noise
photomultiplier tube at the focal point. No evidence for the existence of
hidden photons was found in the latest measurement giving a new limit on the
photon-hidden photon mixing parameter in the hidden photon mass range
0.001-1eV.Comment: 6 pages. Contributed to the 9th Patras Workshop on Axions, WIMPs and
WISPs, Mainz, June 24-28, 201
Development of new additive for grain refinement of austenitic stainless steel
The synthetic vanadinites (Pb(x)Ca(10-x))(VO4)6F2delta, 1 < x < 9, adopt a P6(3)/m apatite structure with 9.7590 (1) < or = a < or = 10.1179 (1) A and 7.0434 (3) < or = c < or = 7.4021 (1) A. The partitioning of calcium and lead over the AI(4f) and AII(6h) positions is nonstoichiometric with lead preferentially entering the larger AII site. High-resolution electron microscopy showed that samples annealed for 10 h at 1073 K are in disequilibrium with calcium- and lead-rich microdomains co-existing at unit-cell scales. For (Pb5Ca5)(VO4)6F2delta, sintering in excess of 2 weeks is required for the metals to order macroscopically. As annealing progresses, c/a, the partitioning coefficient kPb(AI/AII) and the AIO6 metaprism twist angle (phi) adjust cooperatively to enlarge the apatite channel, and thereby accommodate higher lead content. These results demonstrate that phi is a sensitive measure of disequilibrium and a useful device for monitoring changes in apatite topology as a function of composition
EAS development curve at energy of 10(16) - 10(18) eV measured by optical Cerenkov light
The data of optical Cerenkov light from extensive air shower observed at the core distance more than 1 Km at Akeno are reexamined. Applying the new simulated results, the shower development curves for the individual events were constructed. For the showers of 10 to 17th power eV the average depth at the shower maximum is determined to be 660 + or - 40 gcm/2. The shower curve of average development is found to be well described by a Gaisser-Hillas shower development function with above shower maximum depth
Arrival directions of cosmic rays of E .4 EeV
The anisotropy of cosmic rays observed by the Utah Fly's Eye detector has been studied. Emphasis has been placed on examining distributions of events in galactic coordinates. No statistically significant departure from isotropy has been observed for energies greater than 0.4 EeV (1 EeV = 10 to the 18th power eV). Results of the standard harmonic analysis in right ascension are also presented
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