Bragg-like curve for dark matter searches; binary gases

The directional detection of low-energy recoil ions can provide strong possibility for observation of dark matter in the Galaxy. Quenching factors for 5-200 keV recoil ions in N2, CO2, CF4 and CS2 gases are evaluated and Bragg-like curves, the electronic energy deposition as a function of the projected range, are presented. The Bragg-like curves are intended for directional search for the dark matter candidate, WIMPs, using the gas TPC. Quenching factors for very heavy ions produced in alpha-decay in dry air, N2, CO2, CF4 and CS2 are also estimated and compared with experimental values.Comment: Submitted to Rad. Phys. Chem., 18 pages, 9 figure

Babinet's principle in the Fresnel regime studied using ultrasound

The diffraction of ultrasound by a circular disk and an aperture of the same size have been investigated as a demonstration of Babinet's principle in the Fresnel regime. The amplitude and the phase of diffracted ultrasonic waves have been measured, and a graphical treatment of the results is performed by simply drawing vectors (phasors) in the complex plane. The results verify Babinet's principle. It is also found that the incident wave is indeed 90 deg behind the phase of the wave passing through on the central axis of a circular aperture. This paradox has previously been regarded as a defect of Fresnel's theory. The apparatus used is intended as a table-top instrument for the student laboratory in general science and engineering classes.Comment: Am. J. Phys. in internal rev. process, 19 pages with 7 figs., v2: change in presentatio

TV ガメン ニ オケル ジマク ジョウホウ ニ ツイテ

人間にとって映像は大量の情報を瞬時に得られるという意味で重要であるが,説明に字幕文字を入れることも多い。この場合,どのような字幕を入れることが読みやすいものになるか,検討しておくことは,商業放送のように,短時間に送り手の意図を伝達したい場合に重要である。ポスターのような減色混合画面についての検討は多いが,テレビのような加色混合画面についての研究が少ないように思われるので,読み取り時間の測定を主として,その検討を行なった。緑の背景色に対して,文字色は白とすることがよいことが判り,ポスターの場合とは異なる結果となった。また,その場合に適切な表示方法としては横書きがよく,また,文字数と読み取り時間には明らかな相関があるが,二行表示にしても一行表示と同程度の時間しかかからないので,文字数の多い場合,二行表示にした方がよい。表示位置については,左右よりも上か下にした方がよい。そして,このことはアイカメラの軌跡からも確認された

フセイ アクセス ノ コンセキ ジョウホウ オ モチイタ タイムラインガタ イベントログ カシカキノウ ノ カイハツ

企業のサービス，システムなどの情報を窃取することを目的とする攻撃に関連して，RAT（遠隔操作ツール）による攻撃被害事例などが報告されている．そして，無差別な攻撃のみならず，特定の組織や企業に対象を絞って攻撃を行う標的型攻撃の脅威が増加傾向にあり，感染原因や被害範囲を特定する手法としてデジタル・フォレンジックの重要性が高まっている．本研究では，Windowsを対象として，不正に侵入を受けたシステム上の痕跡情報から，攻撃者が行った一連の攻撃活動を可視化し，マルウェアの攻撃手順，ファイルの改ざんや攻撃者の目的を解析するログ解析支援ツールを開発している．本論文では，インシデント対応時の痕跡情報抽出作業から抽出の判断基準を定義し，ログ解析支援ツールに実装した内容について述べる．次に，平常時に記録されるログからフィルタ処理，ファイル改ざん等の不正な操作が行われた可能性の高いログを抽出して時系列に可視化するタイムライン型のイベントログ可視化機能について報告する．Several damages caused by RAT （remote access tools） have been reported in association with attacks aimed at stealing information regarding corporate services and systems. In addition to indiscriminate attacks, the threat of targeted attacks aimed at specific organizations and companies is increasing. Digital forensics has therefore become increasingly important as a method for identifying the cause of infection and the extent of damage. Hence, in this research, we developed a log analysis support tool for the Windows operating system to visualize the series of activities performed by an attacker by incorporating trace information obtained from the compromised computer system. Furthermore, the proposed log analysis support tool can analyze the malware’s attack procedure, file tampering, and the attacker’s objective. In this paper, we defined the criteria for extracting trace information while responding to various incidents and accordingly implemented them for the proposed log analysis support tool. Furthermore, we demonstrate a timeline-based event log visualization function that extracts logs having a high probability of illegal operations（such as file tampering and filtering of logs recorded at normal times）

Luminescence Response and Quenching Models for Heavy Ions of 0.5 keV to 1 GeV/n in Liquid Argon and Xenon

Biexcitonic collision kinetics with prescribed diffusion in the ion track core have been applied for scintillation response due to heavy ions in liquid argon. The quenching factors q = EL/E, where E is the ion energy and EL is the energy expended for luminescence, for 33.5 MeV/n 18O and 31.9 MeV/n 36Ar ions in liquid Ar at zero field are found to be 0.73 and 0.46, compared with measured values of 0.59 and 0.46, respectively. The quenching model is also applied for 80–200 keV Pb recoils in α-decay, background candidates in direct dark matter searches, in liquid argon. Values obtained are ~0.09. A particular feature of Birks’ law has been found and exploited in evaluating the electronic quenching factor qel in liquid Xe. The total quenching factors qT for 0.5–20 keV Xe recoils needed for weakly interacting massive particle (WIMP) searches are estimated to be ~0.12–0.14, and those for Pb recoils of 103 and 169 keV are 0.08 and 0.09, respectively. In the calculation, the nuclear quenching factor qnc = Eη/E, where Eη is the energy available for the electronic excitation, is obtained by Lindhard theory and a semi-empirical theory by Ling and Knipp. The electronic linear energy transfer plays a key role