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 $\lambda$ by using a ferromagnetic sample with a dimension $l$, the sensitivity of the graviton-magnon detector reaches spectral densities, around $5.4 \times 10^{-22} \times (\frac{l}{\lambda /2\pi})^{-2} \ [{\rm Hz}^{-1/2}]$at 14 GHz and$8.6 \times 10^{-21} \times (\frac{l}{\lambda /2\pi})^{-2} \ [{\rm Hz}^{-1/2}]$ 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($\mu$-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 $\rm {}^{3}He$(n,p(573 keV))$\rm {}^{3}H(191 keV)$ reaction is about 1.2 cm, and that both particles have large energy losses ($\rm > 200 keV/cm$) in 1 atm Ar+$\rm C_{2}H_{6}(10$+${}^{3}$He($< 1$). 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 $18^\circ$ and $35^\circ$, 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($\mu$-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 $\mu$-PIC, with the detection area of 10$\times$10 cm${}^{2}$ and 65536 anode electrodes of 400 $\mu$m pitch. We achieved the gas gain of over 10000 without any other multipliers. With the pipe-line readout system specially developed for the $\mu$-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 $\mu$-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

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.

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($\rm CF_4$) 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

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