323 research outputs found
Probing GHz Gravitational Waves with Graviton-magnon Resonance
A novel method for extending frequency frontier in gravitational wave
observations is proposed. It is shown that gravitational waves can excite a
magnon. Thus, gravitational waves can be probed by a graviton-magnon detector
which measures resonance fluorescence of magnons. Searching for gravitational
waves with a wave length by using a ferromagnetic sample with a
dimension , the sensitivity of the graviton-magnon detector reaches spectral
densities, around $5.4 \times 10^{-22} \times (\frac{l}{\lambda /2\pi})^{-2} \
[{\rm Hz}^{-1/2}]8.6 \times 10^{-21} \times (\frac{l}{\lambda
/2\pi})^{-2} \ [{\rm Hz}^{-1/2}]$ at 8.2 GHz, respectively.Comment: 5 pages, 1 figure, minor change
Challenges for the directional dark matter direct detection
Directional methods have been considered to provide a solid proof for the
direct detection of the dark matter. Gaseous time-projection-chambers (TPCs)
are the most mature devices for directional dark matter searches although there
still exist several challenges to overcome. This paper reviews the history,
current challenges and future prospects of the gaseous TPCs for directional
dark matter searches.Comment: 12 pages, 7figures, prepared for the submission to Journal of
Advanced Instrumentation in Scienc
Performance of a micro-TPC for a time-resolved neutron PSD
We report on the performance of a micro-TPC with a micro pixel
chamber(-PIC) readout for a time-resolved neutron position-sensitive
detector(PSD). Three-dimensional tracks and the Bragg curves of protons with
energies of around 1 MeV were clearly detected by the micro-TPC. More than 95%
of gamma-rays of 511 keV were found to be discriminated by simple analysis.
Simulation studies showed that the total track length of proton and triton
emitted from the (n,p(573 keV)) reaction is
about 1.2 cm, and that both particles have large energy losses () in 1 atm Ar++He(). These values
suit the current performance of the micro-TPC, and we conclude that a
time-resolved neutron PSD with spatial resolution of sub-millimeters shall be
developed as an application of the micro-TPC.Comment: 13 pages, 10 figures, to appear in NIM
Development of an advanced Compton camera with gaseous TPC and scintillator
A prototype of the MeV gamma-ray imaging camera based on the full
reconstruction of the Compton process has been developed. This camera consists
of a micro-TPC that is a gaseous Time Projection Chamber (TPC) and
scintillation cameras. With the information of the recoil electrons and the
scattered gamma-rays, this camera detects the energy and incident direction of
each incident gamma-ray. We developed a prototype of the MeV gamma-ray camera
with a micro-TPC and a NaI(Tl) scintillator, and succeeded in reconstructing
the gamma-rays from 0.3 MeV to 1.3 MeV. Measured angular resolutions of ARM
(Angular Resolution Measure) and SPD (Scatter Plane Deviation) for 356 keV
gamma-rays were and , respectively.Comment: 4 pages, 5 figures. Proceedings of the 6th International Workshop On
Radiation Imaging Detector
Performance of the TPC with Micro Pixel Chamber Readout: micro-TPC
Micro-TPC, a time projection chamber(TPC) with micro pixel chamber(-PIC)
readout was developed for the detection of the three-dimensional fine(sub-m
illimeter) tracks of charged particles. We developed a two-dimensional position
sensitive gaseous detector, or the -PIC, with the detection area of
1010 cm and 65536 anode electrodes of 400 m pitch. We
achieved the gas gain of over 10000 without any other multipliers. With the
pipe-line readout system specially developed for the -PIC, we detected
X-rays at the rate as high as 7.7 Mcps. We attached a drift cage with an 8 cm
drift length to the -PIC and developed a micro-TPC. We measured the basic
performances of the micro-TPC and took three-dimensional tracks of electrons.
We also developed a prototype of the MeV gamma-ray imaging detector which is a
hybrid of the micro-TPC and NaI(Tl) scintillators and confirmed its concept by
reconstructing the obtained data.Comment: 6 pages 16 figures, submitted for IEEE/TNS 200
Simulation study of electron drift and gas multiplication in Micro Pixel Chamber
The physical processes of charge collection and gas multiplication of a Micro
Pixel Chamber (mu-PIC) were studied in detail using a three-dimensional
simulation. The collection efficiencies of primary electrons and gas
multiplication factors were calculated for several electrode structures. Based
on those studies, we analyzed the optimization of the electrode structure of
the mu-PIC, in order to obtain a high gas gain of more than 10^4 and a
simultaneous suppression of discharges. Consequently, we found that these
characteristics strongly depend on the substrate thickness and the anode
diameter of the mu-PIC. In addition, a gas gain of 10^5 would be expected for a
mu-PIC having a thick substrate of > 150um.Comment: 16 pages, 14 figures, Submitted to Nucl. Instr. Methods
Detecting the WIMP-wind via spin-dependent interactions
Revealing the nature of dark matter is one of the most interesting tasks in
astrophysics. Measuring the distribution of recoil angles is said to be one of
the most reliable methods to detect a positive signature of dark matter. We
focused on measurements via spin-dependent interactions, and studied the
feasibility with carbon tetrafluoride() gas, while taking into
account the performance of an existing three-dimensional tracking detector. We
consequently found that it is highly possible to detect a positive signature of
dark matter via spin-dependent interactions.Comment: 14 pages, 5 figures, submitted for Physics Letters
Direction-sensitive dark matter search results in a surface laboratory
We developed a three-dimensional gaseous tracking device and performed a
direction-sensitive dark matter search in a surface laboratory. By using 150
Torr carbon-tetrafluoride (CF_4 gas), we obtained a sky map drawn with the
recoil directions of the carbon and fluorine nuclei, and set the first limit on
the spin-dependent WIMP (Weakly Interacting Massive Particles)-proton cross
section by a direction-sensitive method. Thus, we showed that a WIMP-search
experiment with a gaseous tracking device can actually set limits. Furthermore,
we demonstrated that this method will potentially play a certain role in
revealing the nature of dark matter when a low-background large-volume detector
is developed.Comment: 9 figures, accepted for publication in Phys. Lett.
Performance of a Time-Projection-Chamber with a Large-Area Micro-Pixel-Chamber Readout
A micro time-projection-chamber (micro-TPC) with a detection volume of
23*28*31 cm^3 was developed, and its fundamental performance was examined. The
micro-TPC consists of a micro pixel chamber with a detection area of 31*31 cm^2
as a two-dimensional imaging device and a gas electron multiplier with an
effective area of 23*28 cm^2 as a pre-gas-multiplier. The micro-TPC was
operated at a gas gain of 50,000, and energy resolutions and spatial
resolutions were measured.Comment: 4 pages, 7 figures, proceedings of IWORID
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