低能量阈高纯锗探测器用于暗物质探测实验研究

一个位于韩国江原道襄阳郡地下实验室的暗物质WIMP探测实验中, 采用了低能量阈高纯锗探测器, 带有碘化铯晶体反符合探测器作为主动屏蔽体. 整个系统设置和能量标定已经完成, 并且已经积累了约155d的本底数据. 还应用外置伽玛源和中子源进行了实验, 以判断本底的来源. 介绍了数据的分析和初步结果, 并给出了实验诱人的前景.     

非重子冷暗物质粒子的研究进展

暗物质问题目前已受到物理学界的高度关注，因为这一课题的研究和进展，将直接影响到粒子物理、天体物理和宇宙学的发展方向。当前世界上已有一些大的实验组正在开展这方面的研究工作，并已取得了一定的结果；文章重点介绍两个重要的探测实验，即中意合作DAMA组（Dark Matter Group)100kg Nal（Tl）探测器阵列实验和美国的CDMS（Cold Dark Matter Search）实验组的低温探测器实验。详细介绍了DAMA实验的物理分析方法及其实验结果，并同CDMS实验结果进行了相应的比较。     

Constraining WIMP magnetic moment from CDMS II experiment

We consider a degenerate or a nearly degenerate dark matter sector where a sizable magnetic moment of a (almost) Dirac type neutral dark matter candidate N is anticipated. Then, due to soft photon exchange, the cross-section in direct detection of N   can be enhanced at low Q²$Q^2$ region. We discuss the implication of this type of models in view of the recent CDMS II report.     

The spacetime associated with galactic dark matter halos

We show how an adequate post-Newtonian generalization can be obtained for Newtonian dark matter halos associated with an empiric density profile. Applying this approach to halos that follow from the well known numerical simulations of Navarro, Frenk and White (NFW), we derive all dynamical variables and show that NFW halos approximately follow an ideal gas type of equation of state which fits very well to a polytropic relation in the region outside the core. This fact suggests that outer regions of NFW halos might be related to equilibrium states in the non-extensive Statistical Mechanics formalism proposed by Tsallis.     

Particle asymmetries in the early universe

The total lepton asymmetry l=∑_fl_f in our universe is only poorly constrained by theories and experiments. It might be orders of magnitudes larger than the observed baryon asymmetry b?O(10⁻¹⁰), |l|/b≤O(10⁹). We found that the dynamics of the cosmic QCD transition changes for large asymmetries. Predictions for asymmetries in a single flavour l_f allow even larger values. We find that asymmetries of l_f≤O(1) in single or two flavours may change the relic abundance of WIMPs. However, large lepton and large individual lepton flavour asymmetries influence significantly the dynamics of the early universe between the electroweak phase transition and the onset of neutrino oscillations.     

Final results of the EDELWEISS-II WIMP search using a 4-kg array of cryogenic germanium detectors with interleaved electrodes

The EDELWEISS-II Collaboration has completed a direct search for WIMP dark matter with an array of ten 400-g cryogenic germanium detectors in operation at the Laboratoire Souterrain de Modane. The combined use of thermal phonon sensors and charge collection electrodes with an interleaved geometry enables the efficient rejection of γ-induced radioactivity as well as near-surface interactions. A total effective exposure of 384 kg d has been achieved, mostly coming from fourteen months of continuous operation. Five nuclear recoil candidates are observed above 20 keV, while the estimated background is 3.0 events. The result is interpreted in terms of limits on the cross-section of spin-independent interactions of WIMPs and nucleons. A cross-section of 4.4×¹⁰−8 pb is excluded at 90%CL for a WIMP mass of 85 GeV. New constraints are also set on models where the WIMP-nucleon scattering is inelastic.     

WIMP dark matter in gauge-mediated SUSY breaking models and its phenomenology

We propose an extended version of the gauge-mediated SUSY breaking models where extra SUL₍₂₎$\mathit{SU}{(2)}_L$ doublets and singlet field are introduced. These fields are assumed to be parity-odd under an additional matter parity. In this model, the lightest parity-odd particle among them would be dark matter in the Universe. In this Letter, we discuss direct detection of the dark matter and the collider signatures of the model.     

First underground results with NEWAGE-0.3a direction-sensitive dark matter detector

A direction-sensitive dark matter search experiment at Kamioka underground laboratory with the NEWAGE-0.3a detector was performed. The NEWAGE-0.3a detector is a gaseous micro-time-projection chamber filled with CF₄ gas at 152 Torr. The fiducial volume and target mass are 20×25×31 cm³$20\times 25\times 31{\text{cm}}^3$ and 0.0115 kg, respectively. With an exposure of 0.524 kg days, improved spin-dependent weakly interacting massive particle (WIMP)-proton cross section limits by a direction-sensitive method were achieved including a new record of 5400 pb for 150 GeV/c²$/c^2$ WIMPs. We studied the remaining background and found that ambient γ-rays contributed about one-fifth of the remaining background and radioactive contaminants inside the gas chamber contributed the rest.     

暗物质的直接实验探测

暗物质研究是21世纪粒子物理、天体物理和宇宙学最重要的前沿科学课题之一.暗物质被天文学中的引力效应所观察到,但对它的存在和认识仍旧是个谜.文章主要论述了对弱作用大质量暗物质粒子(WIMP)直接探测的基本原理、各种直接探测技术、当前的实验进展和发展方向.最后给出了最近的实验物理结果.