Precise and Automated Measurement of Ferroelectric Hysteresis Loop

Precise hysteresis loops of ferroelectric crystal have been deduced from the switching current caused by application of triangular field. The contributions of conduction and capacity of the crystal were subtracted from the current, and the pure ferroelectric polarization was obtained from the integration of remaining current. All the procedure was performed by the use of personal computer. Not only the parameters of hysteresis loop (spontaneous polarization P_s, coercive field E_c, bias field E_b) but also the dielectric constant ε_r were automatically obtained in a wide frequency range. The temperature dependence of P_s of triglycine sulfate in a wide temperature range was investigated.誘電体の中には外部から電場を印加しなくても誘電分極を生じるものがある。この分極は自発分極P_sと呼ばれているが，この自発分極がその方向と逆向きの外部電場を印加することによって反転できるものを強誘電体という。強誘電体に外部電場E を印加すると，自発分極が反転可能なために，分極Pの特性は非線形な履歴曲線（ヒステリシスループ，P-Eプロット）を描く。この曲線から強誘電体の性質を表す様々なパラメーター（自発分極P_s，抗電場Ec，内部バイアス電場E_bなど）が得られる。この曲線は一般にSawyerTower回路を用いて測定されるが，その場合には，伝導度や容量による寄与が加わっていて純粋な分極反転だけを表す履歴曲線を正確に測定することが困難である。また，その回路では低周波測定は実際には非常に困難である。そこで印加電場Eに対する反転電流Iの履歴曲線（J-Eプロット）からの測定を試みた。この曲線から前記の余分な寄与をコンピューターにより自動的に取り除くことによって，より正確に強誘電体の履歴曲線を描くことが可能であるからである。また，この測定法では，低周波測定が可能であるので，抗電場が大きくなる低温での測定も可能である。この報告では，強誘電体の一つである硫酸グリシン（略して，TGS）を試料として用い，そのI-E履歴曲線による測定法によって自発分極の温度依存性を広範囲にわたって詳しく調べたので，その結果を報告する

Perturbative calculation of improvement coefficients to O(g2a) for bilinear quark operators in lattice QCD

We calculate the O(g2a) mixing coefficients of bilinear quark operators in lattice QCD using a standard perturbative evaluation of on-shell Green’s functions. Our results for the plaquette gluon action are in agreement with those previously obtained with the Schrödinger functional method. The coefficients are also calculated for a class of improved gluon actions having six-link terms

Charm quark system at the physical point of 2+1 flavor lattice QCD

We investigate the charm quark system using the relativistic heavy quark action on 2+1 flavor PACS-CS configurations previously generated on $32^3 \times 64$ lattice. The dynamical up-down and strange quark masses are set to the physical values by using the technique of reweighting to shift the quark hopping parameters from the values employed in the configuration generation. At the physical point, the lattice spacing equals $a^{-1}=2.194(10)$ GeV and the spatial extent $L=2.88(1)$ fm. The charm quark mass is determined by the spin-averaged mass of the 1S charmonium state, from which we obtain m_{\rm charm}^{\msbar}(\mu = m_{\rm charm}^{\msbar}) = 1.260(1)(6)(35) GeV, where the errors are due to our statistics, scale determination and renormalization factor. An additional systematic error from the heavy quark is of order $\alpha_s^2 f(m_Q a)(a \Lambda_{QCD})$, which is estimated to be a percent level if the factor $f(m_Q a)$ analytic in $m_Q a$ is of order unity. Our results for the charmed and charmed-strange meson decay constants are $f_D=226(6)(1)(5)$ MeV, $f_{D_s}=257(2)(1)(5)$ MeV, again up to the heavy quark errors of order $\alpha_s^2 f(m_Q a)(a \Lambda_{QCD})$. Combined with the CLEO values for the leptonic decay widths, these values yield $|V_{cd}| = 0.205(6)(1)(5)(9)$, $|V_{cs}| = 1.00(1)(1)(3)(3)$, where the last error is on account of the experimental uncertainty of the decay widths.Comment: 16 pages, 12 figure

バーミヤーン遺跡における環境調査（1）―外部環境と石窟内の温湿度環境―

Outdoor environment influences the microclimate of caves and the condition of mural paintings. However, sufficient meteorological observation has not been made in the Bamiyan area. In order to monitor basic weather elements (air temperature, relative humidity, wind speed and its direction, solar radiation, amount of rain fall and depth of snow) of the Bamiyan site, an automatic weather station was installed on the rooftop of the Bamiyan Centre for Cultural Heritage Conservation. Furthermore, the microclimates in the caves are being monitored. Air temperature and relative humidity in Caves I, K3, M and N (a), and moisture content in the walls of Caves I and N (a) are being measured. Obtained data indicate that the conditions in Caves I and N (a) received a strong impact from outdoor conditions since these caves had openings to outside. The diurnal range of the outdoor temperature was 15ºC, and that in Cave I was 10ºC whilst that in Cave N (a) was 6ºC. This difference between the data of Caves I and N (a) could be due to the size of the openings to outside. Cave M was closed by a wooden door and brick wall. The data showed that its interior condition was quite stable. The temperature was around 15ºC without any daily fluctuations. This condition might be favourable for the state of conservation of the mural paintings

ρ\rho Meson Decay in 2+1 Flavor Lattice QCD

We perform a lattice QCD study of the $\rho$ meson decay from the $N_f=2+1$ full QCD configurations generated with a renormalization group improved gauge action and a non-perturbatively $O(a)$-improved Wilson fermion action. The resonance parameters, the effective $\rho\to\pi\pi$ coupling constant and the resonance mass, are estimated from the $P$-wave scattering phase shift for the isospin I=1 two-pion system. The finite size formulas are employed to calculate the phase shift from the energy on the lattice. Our calculations are carried out at two quark masses, $m_\pi=410\,{\rm MeV}$ ($m_\pi/m_\rho=0.46$) and $m_\pi=300\,{\rm MeV}$ ($m_\pi/m_\rho=0.35$), on a $32^3\times 64$ ($La=2.9\,{\rm fm}$) lattice at the lattice spacing $a=0.091\,{\rm fm}$. We compare our results at these two quark masses with those given in the previous works using $N_f=2$ full QCD configurations and the experiment.Comment: LaTeX2e, 24 pages, 9 eps figures, uses revtex4 and graphicx, published in PR

塔里木沙漠公路防护林土壤微生物生物量与土壤环境因子的关系

为探讨极端干旱区风沙土土壤微生物与土壤环境因子的作用规律,采用相关分析法研究了塔里木沙漠公路防护林地土壤微生物生物量与理化因子和酶活性的关系.结果表明:土壤容重和粒径减小(R0.85)时,防护林地中土壤微生物数量和生物量有增大趋势,由容重与微生物量的相关性主导;土壤养分含量与土壤微生物数量和生物量呈正相关,主要由速效养分和放线菌、微生物生物量C、P的相关性所致;土壤酶活性与土壤微生物数量和生物量的相关性差异较大,R在0.51～0.91,主要取决于蔗糖酶、磷酸酶与放线菌、微生物量C的相关;土壤盐分增加不利于土壤微生物生物量的积累(R0.63).实践中应为干旱区林地土壤微生物营造良好的土体,促进土壤物质循环