483 research outputs found
A new method of alpha ray measurement using a Quadrupole Mass Spectrometer
We propose a new method of alpha()-ray measurement that detects
helium atoms with a Quadrupole Mass Spectrometer(QMS). A demonstration is
undertaken with a plastic-covered Am -emitting source to detect
-rays stopped in the capsule. We successfully detect helium atoms that
diffuse out of the capsule by accumulating them for one to 20 hours in a closed
chamber. The detected amount is found to be proportional to the accumulation
time. Our method is applicable to probe -emitting radioactivity in bulk
material.Comment: 8 pages, 6 figure
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
An x-ray detector using PIN photodiodes for the axion helioscope
An x-ray detector for a solar axion search was developed. The detector is
operated at 60K in a cryostat of a superconducting magnet. Special care was
paid to microphonic noise immunity and mechanical structure against thermal
contraction. The detector consists of an array of PIN photodiodes and tailor
made preamplifiers. The size of each PIN photodiode is $11\times 11\times 0.5\
{\rm mm^3}$ and 16 pieces are used for the detector. The detector consists of
two parts, the front-end part being operated at a temperature of 60K and the
main part in room temperature. Under these circumstances, the detector achieved
1.0 keV resolution in FWHM, 2.5 keV threshold and 6\times 10^{-5} counts
sec^{-1} keV^{-1} cm^{-2} background level.Comment: 8 pages, 5 figures, submitted to Nucl. Instr. Meth.
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