45 research outputs found
Tokyo Axion Helioscope
The idea of a magnetic axion helioscope was first proposed by Pierre Sikivie
in 1983. Tokyo axion helioscope was built exploiting its detection principle
with a dedicated cryogen-free superconducting magnet and PIN photodiodes for
x-ray detectors. Solar axions, if exist, would be converted into x-ray photons
in the magnetic field. Conversion is coherently enhanced even for massive
axions by filling the conversion region with helium gas. Its start up, search
results so far and prospects are presented.Comment: 5 pages, 3 figures, AXIONS 201
Measurement of the Polarization Parameters for the π-p→π°n Charge Exchange Scattering in the Momentum Region between 1.965 and 2.960 GeV/c
Hidden photon CDM search at Tokyo
We report on a search for hidden photon cold dark matter (HP CDM) using a
novel technique with a dish antenna. We constructed two independent apparatus:
one is aiming at the detection of the HP with a mass of which
employs optical instruments, and the other is for a mass of
utilizing a commercially available parabolic
antenna facing on a plane reflector. From the result of the measurements, we
found no evidence for the existence of HP CDM and set upper limits on the
photon-HP mixing parameter .Comment: Contributed to the 11th Patras Workshop on Axions, WIMPs and WISPs,
Zaragoza, June 22 to 26, 201
Direct search for solar axions by using strong magnetic field and X-ray detectors
We have searched for axions which could be produced in the solar core by
exploiting their conversion to X rays in a strong laboratory magnetic field.
The signature of the solar axion is an increase in the rate of the X rays
detected in a magnetic helioscope when the sun is within its acceptance.
From the absence of such a signal we set a 95% confidence level limit on the
axion coupling to two photons GeV, provided the axion mass eV. The limit on the
coupling is factor 4.5 more stringent than the recent experimental result. This
is the first experiment whose sensitivity to is higher than
the limit constrained by the solar age consideration.Comment: 11 pages, REVTeX, 4 eps figures included, submitted to PL
A liquid-helium cooled large-area silicon PIN photodiode x-ray detector
An x-ray detector using a liquid-helium cooled large-area silicon PIN
photodiode has been developed along with a tailor-made charge sensitive
preamplifier whose first-stage JFET has been cooled. The operating temperature
of the JFET has been varied separately and optimized. The x- and -ray
energy spectra for an \nuc{241}{Am} source have been measured with the
photodiode operated at 13 K. An energy resolution of 1.60 keV (FWHM) has been
obtained for 60-keV rays and 1.30 keV (FWHM) for the pulser. The
energy threshold could be set as low as 3 keV. It has been shown that a silicon
PIN photodiode serves as a low-cost excellent x-ray detector which covers large
area at 13 K.Comment: 6 pages, and 3 figures, Elsevier macros elsart.sty and elsart12.sty
are neede
Sensitive germanium thermistors for cryogenic thermal detector of Tokyo dark matter search programme
Sensitive n-type and p-type germanium thermistors were fabricated by the melt
doping technique and by the neutron transmutation doping (NTD) technique,
respectively, aiming at a use for the cryogenic thermal detector, or bolometer
of Tokyo dark matter search programme. We report on the measurements of the
sensitivities of these thermistors. In particular, the p-type thermistors are
sensitive enough to scale up our existing prototype LiF bolometer and realize a
multiple array of the bolometers with the total absorber mass of about 1\,kg.Comment: 14 pages, revtex, with 4 postscript figures appended (uuencoded
Trace Element Analysis of Potassium by Resonance Ionization Mass Spectrometry
A simple resonance ionization mass spectrometer is built with a Quadrupole
Mass Spectrometer (QMS) and two laser diodes aiming at trace analysis of
potassium. The overall detection efficiency is estimated comparing the yields
of resonance ionization and electron-impact ionization in the same QMS. A clear
discrimination of , and is demonstrated
with a help of isotope shifts of the atomic levels.Comment: 14 pages, 9 figures, submitted to JJA
Measurements of anisotropic scintillation efficiency for carbon recoils in a stilbene crystal for dark matter detection
It is known that scintillation efficiency of organic single crystals depends
on the direction of nuclear recoils relative to crystallographic axes. This
property could be applied to the directional WIMP dark matter detector.
The scintillation efficiency of carbon recoils in a stilbene crystal was
measured for recoil energies of 30 keV to 1 MeV using neutrons from
Li(p,n)Be and Cf. Anisotropic response was confirmed in low
energy regions. The variation of the scintillation efficiency was about 7 %,
that could detect the possible dark matter signal.Comment: 12 pages, 6 figures, to be published in Physics Letters