First measurement of the Head-Tail directional nuclear recoil signature at energies relevant to WIMP dark matter searches
S. Burgos, E. Daw, J. Forbes, C. Ghag, M. Gold, C. Hagemann, V. A. Kudryavtsev, T. B. Lawson, D. Loomba, P. Majewski, D. Muna, A. StJ. Murphy, G. G. Nicklin, S.… 展开作者
S. Burgos, E. Daw, J. Forbes, C. Ghag, M. Gold, C. Hagemann, V. A. Kudryavtsev, T. B. Lawson, D. Loomba, P. Majewski, D. Muna, A. StJ. Murphy, G. G. Nicklin, S. M. Paling, A. Petkov, S. J. S. Plank, M. Robinson, N. Sanghi, D. P. Snowden-Ifft, N. J. C. Spooner, J. Turk, E. Tziaferi
We present first evidence for the so-called Head-Tail asymmetry signature of neutron-induced nuclear recoil tracks at energies down to 1.5 keV/amu using the 1m^3 DRIFT-IIc dark matter detector. This regime is appropriate for recoils induced by Weakly Interacting Massive Particle (WIMPs) but one where the differential ionization is poorly understood. We show that the distribution of recoil energies and directions induced here by Cf-252 neutrons matches well that expected from massive WIMPs. The results open a powerful new means of searching for a galactic signature from WIMPs.
First Results from the Cryogenic Dark Matter Search in the Soudan Underground Lab
我们报告了在苏丹地下实验室的低温暗物质搜索(CDMS)实验中寻找弱相互作用大质量粒子(WIMP)的第一个结果。四个Ge和两个Si探测器运行了52.6个生存日,提供了19.4 kg-d的Ge净曝光后,反冲能量在10- 100 keV之间的削减。仅使用校准数据进行盲分析,以定义核反冲候选物的能量阈值和选择标准。使用标准的暗物质晕和核物理学WIMP模型,这些数据为所有WIMP质量超过15 GeV的相干WIMP-核子标量截面设定了世界上最低的排斥极限,排除了中性伴子超对称模型的重要范围。在90% C. L.时,该极限曲线的最小值在WIMP质量为60 GeV时,它的体积为4 x 10^{-43} cm ^2。
Among the many experimental techniques available, those providing directional information have the potential of yielding an unambiguous observation of WIMPs even in the presence of insidious backgrounds. A measurement of the distribution of arrival direction of WIMPs can also discriminate between Galactic Dark Matter halo models. In this article, I will discuss the motivation for directional detectors and review the experimental techniques used by the various experiments. I will then describe one of them, the DMTPC detector, in more detail.
In LambdaCDM, massive satellites are dragged into the disk-plane by dynamical friction where they dissolve into a stellar thick disk and a more massive dark matter disk. The distinctive kinematics of the dark disk matches the stars that also entered in the satellites. The lower velocities of the dark disk with respect to the Earth enhances detection rates at low recoil energy. For WIMP masses > 50 GeV/c^2, the detection rate increases by up to a factor of 3 in the 5 - 20 keV recoil energy range. Comparing this with rates at higher energy will improve constraints on the WIMP mass, particularly …
Liquid xenon is an important detection medium in direct dark matter experiments, which search for low-energy nuclear recoils produced by the elastic scattering of WIMPs with quarks. The two existing measurements of the relative scintillation efficiency of nuclear recoils below 20 keV lead to inconsistent extrapolations at lower energies. This results in a different energy scale and thus sensitivity reach of liquid xenon dark matter detectors. We report a new measurement of the relative scintillation efficiency below 10 keV performed with a liquid xenon scintillation detector, optimized for max…
The ZEPLIN-III experiment in the Palmer Underground Laboratory at Boulby uses a 12kg two-phase xenon time projection chamber to search for the weakly interacting massive particles (WIMPs) that may account for the dark matter of our Galaxy. The detector measures both scintillation and ionisation produced by radiation interacting in the liquid to differentiate between the nuclear recoils expected from WIMPs and the electron recoil background signals down to ~10keV nuclear recoil energy. An analysis of 847kg.days of data acquired between February 27th 2008 and May 20th 2008 has excluded a WIMP-nu…
Limits on spin-independent WIMP-nucleon interactions from the two-tower run of the Cryogenic Dark Matter Search
我们报告了苏丹地下实验室低温暗物质搜寻(CDMS II)的新结果。两个塔,每个由6个探测器组成,运行了74.5个工作日,在切割后,锗的光谱加权曝光量为34 kg-d,硅靶的光谱加权曝光量为12 kg-d,平均反冲能量为10-100 keV,WIMP质量为60 GeV。进行了盲分析,结合了拒绝表面事件的改进技术。未观察到超过预期背景的WIMP信号。当结合我们以前的结果从苏丹,90%的C. L。对于60 GeV的WIMP质量,自旋无关的WIMP-核子截面的上限是Ge为1.6 x 10^{-43} cm ^2,Si为3 x 10^{-42} cm ^2。Ge(Si)的组合极限比我们以前的结果低2.5(10)倍,并限制了超对称模型的预测。