arXiv subjects

Makoto Minowa

Publications and source records attributed to Makoto Minowa.

13 recordsLinked to original sources

arXiv2020

GroundBIRD : A CMB polarization experiment with MKID arrays

GroundBIRD is a ground-based experiment for the precise observation of the polarization of the cosmic microwave background (CMB). To achieve high sensitivity at large angular scale, we adopt three features in this experiment: fast rotation scanning, microwave kinetic inductance detector (MKID) and cold optics. The rotation scanning strategy has the advantage to suppress $1/f$ noise. It also provides a large sky coverage of 40\%, which corresponds to the large angular scales of $l \sim 6$. This allows us to constrain the tensor-to-scalar ratio by using low $l$ B-mode spectrum. The focal plane consists of 7 MKID arrays for two target frequencies, 145 GHz and 220 GHz band. There are 161 pixels in total, of which 138 are for 144 GHz and 23 are for 220 GHz. This array is currently under development and the prototype will soon be evaluated in telescope. The GroundBIRD telescope will observe the CMB at the Teide observatory. The telescope was moved from Japan to Tenerife and is now under test. We present the status and plan of the GroundBIRD experiment.

astro-ph.IM↗

arXiv2020

Search for hidden-photon cold dark matter using a K-band cryogenic receiver

We search for hidden-photon cold dark matter (HP-CDM) using a spectroscopic system in a K-band frequency range. Our system comprises a planar metal plate and cryogenic receiver. This is the first time a cryogenic receiver has been used in the search for HP-CDM. Such use helps reduce thermal noise. We recorded data for 9.3 hours using an effective aperture area of 14.8 cm$^2$. No signal was found in the data. We set upper limits for the parameter of mixing between the photon and HP-CDM in the mass range from 115.79 to 115.85 $μ$eV, $χ< 1.8$-$4.3 \times 10^{-10}$, at a 95% confidence level. This is the most stringent upper limit obtained to date in the considered mass range.

hep-ex↗

arXiv2015

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 $\sim\,\rm{eV}$ which employs optical instruments, and the other is for a mass of $\sim5\times10^{-5}\, \rm{eV}$ 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 $χ$.

hep-ex↗

arXiv2013

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.

hep-ex↗

arXiv2012

A mobile antineutrino detector with plastic scintillators

We propose a new type segmented antineutrino detector made of plastic scintillators for the nuclear safeguard application. A small prototype was built and tested to measure background events. A satisfactory unmanned field operation of the detector system was demonstrated. Besides, a detailed Monte Carlo simulation code was developed to estimate the antineutrino detection efficiency of the detector.

physics.ins-det↗

arXiv2010

Development of a Compact Resonance Ionization Mass Spectrometer for Trace Element Analysis of Potassium

A compact resonance ionization mass spectrometer is developed using two laser diodes and a quadrupole mass spectrometer to perform trace element analysis of potassium. With the help of a narrow linewidth of the laser diode, the isotope shifts of $^{40}{\rm K}$ and $^{41}{\rm K}$ of the 405 nm line with respect to $^{39}{\rm K}$, corresponding to the transition of $4\,^2$S$_{1/2}\rightarrow$ $5\,^2$P$^\circ_{1/2}$, are measured to be $207\pm13$ MHz and $451\pm10$ MHz, respectively, by comparing them to the known hyperfine splitting widths of the $4\,^2{\rm S}_{1/2}$ ground state of each potassium isotope. The overall detection efficiency of an order of $\sim10^{-6}$ in our setup indicates the availability of RIMS to the analysis of the trace metal impurities on or in a certain material such as the contamination assessment of semiconductor wafers.

physics.atom-ph↗

arXiv2010

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.

astro-ph.IM↗

arXiv2008

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 $^{39}\rm K$, $^{40}\rm K$ and $^{41}\rm K$ is demonstrated with a help of isotope shifts of the atomic levels.

physics.atom-ph↗

arXiv1998

The Tokyo Axion Helioscope Experiment

A preliminary result of the solar axion search experiment at the University of Tokyo is presented. We searched for axions which could be produced in the solar core by exploiting the axion helioscope. The helioscope consists of a superconducting magnet with field strength of 4 Tesla over 2.3 meters. From the absence of the axion signal we set a 95 % confidence level upper limit on the axion coupling to two photons $g_{aγγ} < 6.0 \times 10^{-10} GeV^{-1}$ for the axion mass $m_a < 0.03$ eV. This is the first solar axion search experiment whose sensitivity to $g_{aγγ}$ exceeds the limit inferred from the solar age consideration.

hep-ex↗

arXiv1998

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 $g_{aγγ}\equiv 1/M < 6.0\times 10^{-10}$ GeV$^{-1}$, provided the axion mass $m_a<0.03$ 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 $g_{aγγ}$ is higher than the limit constrained by the solar age consideration.

hep-ex↗

arXiv1997

First Results of Tokyo Dark Matter Search with a Lithium Fluoride Bolometer

The First results of the Tokyo dark matter search programme using a 21-g lithium fluoride bolometer are presented. The background spectrum was measured in the surface laboratory. We derive an exclusion plot for the spin-dependently coupled Weakly Interacting Massive Particles (WIMPs) cross section.

hep-ex↗

arXiv1995

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.

hep-ex↗

arXiv1995

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 $γ$-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 $γ$ 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.

hep-ex↗