电离辐照诱发面阵电荷耦合器暗信号增大试验

针对电荷耦合器件(CCD)在空间轨道环境中应用时易受到辐射损伤的影响,对面阵CCD的电离辐照损伤效应问题进行了试验研究.首先,通过开展面阵CCD60 Co γ射线电离辐照效应试验,在暗场条件下测试了面阵CCD辐照后输出信号随积分时间的变化,并拟合计算出暗信号斜率.然后,对比分析了不同偏置条件下辐照后暗信号退化的试验规律;分析了不同偏置条件下辐照后暗信号的退火恢复情况;分析了不同积分时间、不同总剂量下的暗信号不均匀性的变化规律.最后,阐述了电离辐照损伤诱发面阵CCD暗信号增大的物理机制.结果表明:面阵CCD对电离辐照损伤很敏感,在进行航天器成像系统设计时,要充分考虑CCD受电离辐照损伤带来的影响.     

Antideuteron based dark matter search with GAPS: Current progress and future prospects

The General Antiparticle Spectrometer (GAPS) is a new approach to the indirect detection of dark matter. It relies on searching for primary antideuterons produced in the annihilation of dark matter in the galactic halo. Low energy antideuterons produced through Standard Model processes, such as collisions of cosmic-rays with interstellar baryons, are greatly suppressed compared to primary antideuterons. Thus a low energy antideuteron search provides a clean signature of dark matter. In GAPS antiparticles are slowed down and captured in target atoms. The resultant exotic atom deexcites with the emission of X-rays and annihilation pions, protons and other particles. A tracking geometry allows for the detection of the X-rays and particles, providing a unique signature to identify the mass of the antiparticle. A prototype detector was successfully tested at the KEK accelerator in 2005, and a prototype GAPS balloon flight is scheduled for 2011. This will be followed by a full scale experiment on a long duration balloon from Antarctica in 2014. We discuss the status and future plans for GAPS.     

Current status and future plans for the general antiparticle spectrometer (GAPS)

We discuss current progress and future plans for the general antiparticle spectrometer experiment (GAPS). GAPS detects antideuterons through the X-rays and pions emitted during the deexcitation of exotic atoms formed when the antideuterons are slowed down and stopped in targets. GAPS provides an exceptionally sensitive means to detect cosmic-ray antideuterons. Cosmic-ray antideuterons can provide indirect evidence for the existence of dark matter in such form as neutralinos or Kaluza–Klein particles. We describe results of accelerator testing of GAPS prototypes, tentative design concepts for a flight GAPS detector, and near-term plans for flying a GAPS prototype on a balloon.     

Antideuterons as an indirect dark matter signature: Si(Li) detector development and a GAPS balloon mission

The General AntiParticle Spectrometer (GAPS) is a novel approach for indirect dark matter searches that exploits cosmic antideuterons. GAPS complements existing and planned direct dark matter searches as well as other indirect techniques, probing a different and unique region of parameter space in a variety of proposed dark matter models. The GAPS method involves capturing antiparticles into a target material with the subsequent formation of an excited exotic atom. The exotic atom decays with the emission of atomic X-rays and pions from the nuclear annihilation, which uniquely identifies the captured antiparticle. This technique has been verified through the accelerator testing at KEK in 2004 and 2005. The prototype flight is scheduled from Hokkaido, Japan in 2011, preparatory for a long duration balloon flight from the Antarctic in 2014.     

Indirect search for Dark Matter with H.E.S.S.

Observations of the Galactic center region with the H.E.S.S. telescopes have established the existence of a steady, extended source of gamma-ray emission coinciding with the position of the super massive black hole Sgr A^*. This is a remarkable finding given the expected presence of dense self-annihilating Dark Matter in the Galactic center region. The self-annihilation process is giving rise to gamma-ray production through hadronization including the production of neutral pions which decay into gamma-rays but also through (loop-suppressed) annihilation into final states of almost mono-energetic photons. We study the observed gamma-ray signal (spectrum and shape) from the Galactic center in the context of Dark Matter annihilation and indicate the prospects for further indirect Dark Matter searches with H.E.S.S.     

基于天基光学探测图像初析南大西洋异常区影响

文章针对目前在轨运行的高灵敏度探测类可见光遥感器经过南大西洋异常区（SouthAtlanticAnomaly,SAA）时出现的探测能力降低、目标无法识别等现象,通过卫星在轨获取的SAA天基探测图像研究图像中出现的异常现象机理;提出了基于CCD探测器固有暗像元区的图像特征变化开展SAA影响评估的方法,根据在轨图像暗像元区的均值和标准差、图像区的热像素及活像元等特征参数的统计分析,判断经过SAA过程中连续获取的图像中出现显著影响时的拐点,通过曲线拟合估算出该轨道高度的SAA空间分布特征和边界,依此进一步提出利用在轨天基探测图像给出测量影响该轨道高度卫星SAA区域边界的简单方法;最后,基于SAA对天基探测器件的影响分析结果和认识,给出了高灵敏度探测类卫星避免或消除SAA影响的改进措施和建议。文章采用的数据分析和评估方法为提升SAA对天基探测影响的认识,以及下一步有效开展空间碎片探测工作提供参考。     

Influence of dark matter on light propagation in solar system

We investigated the influence of dark matter on light propagation in the solar system. We assumed the spherical symmetry of spacetime and derived the approximate solution of the Einstein equation, which consists of the gravitational attractions caused by the central celestial body, i.e. the Sun, and the dark matter surrounding it. We expressed the dark matter density in the solar system in the following simple power-law form, ?(t,r)=ρ(t)(?/r)^k$?(t\text{,}r)=\rho (t)(?/r{)}^k$, where t is the coordinate time; r, the radius from the central body; ?, the normalizing factor; k, the exponent characterizing r  -dependence of dark matter density; and ρ(t)$\rho (t)$, the arbitrary function of time t. On the basis of the derived approximate solution, we focused on light propagation and obtained the additional corrections of the gravitational time delay and the relative frequency shift caused by the dark matter. As an application of our results, we considered the secular increase in the astronomical unit reported by Krasinsky and Brumberg (2004) and found that it was difficult to provide an explanation for the observed dAU/dt = 15 ± 4 m/century.     

灰色物元分析的研究

在灰色系统理论的基础上，结合物元分析概念，提出一种新方法，称春为灰色物元分析。实例分析说明评价结果与文「６」一致。     

QCD-scale modified-gravity universe

A possible gluon-condensate-induced modified-gravity model with f(R) ∝ ∣R∣^1/2 has been suggested previously. Here, a simplified version is presented using the constant flat-spacetime equilibrium value of the QCD gluon condensate and a single pressureless matter component (cold dark matter, CDM). The resulting dynamical equations of a spatially-flat and homogeneous Robertson-Walker universe are solved numerically. This simple empirical model allows, in fact, for a careful treatment of the boundary conditions and does not require a further scaling analysis as the original model did. Reliable predictions are obtained for several observable quantities of the homogeneous model universe. In addition, the estimator E_G, proposed by Zhang et al. to search for deviations from standard Einstein gravity, is calculated for linear sub-horizon matter-density perturbations. The QCD-scale modified-gravity prediction for E_G(z) differs from that of the ΛCDM model by about ±10% depending on the redshift z.     

Extrasolar solar-sail trajectories and dark matter

Hyper-thin, high-speed solar-photon sail space probes exploring the Sun?s Oort comet cloud could also be used to set an upper bound to the concentration of WIMPS (weakly interacting massive particles), one of the suggested (but unconfirmed) forms of dark matter within the vicinity of the solar system. Newton?s Shell Theorem would be applied to determine variations in apparent solar mass as the probe moves further out from the Sun. Application of this technique to the trajectories of Pioneer 10/11 reveals that the upper limit to WIMP concentration within ~60 AU of the Sun is ~0.2 Earth masses, as revealed in studies of the Pioneer Anomaly. If the published accuracy of the Pioneer acceleration measurements can be increased by an order of magnitude, probe trajectory measurements out to ~10,000 AU may confirm or falsify the hypothesis that WIMP mass within the solar vicinity is ~3X star mass. It is shown that a space-manufactured ~40-nm thick beryllium hollow-body solar sail deployed from a ~0.07 AU perihelion is a candidate spacecraft for such a mission. Possible science-team organization strategy for a ~100-year mission to ~10,000 AU is discussed.