XMASS

The XMASS detector is a large single phase liquid Xenon scintillator.After its feasibility had been studied using a 100 kg size prototype detector, an 800 kg size detector is being built for dark matter search with the sensitivity of $10^{-45} {\rm cm}^2$ region in spin-independent cross section. The results of R\&D study for 800 kg detector, especially ultra low background technologies, and the prospects of the experiment are described.Comment: 6 pages, 7 figures, for the proceedings of the 1st International Workshop towards the Giant Liquid Argon Charge Imaging Experiment (GLA2010, will be published in Journal of Physics, Conference Series (Editors: T. Hasegawa and A. Rubbia)

Sacral Stress Fracture following the Bone Union of Lumbar Spondylolysis

While 22 articles have reported on sacral stress fractures, it is a rare injury and its etiology is not well known. We present the case of a 16-year-old male who presented with low back pain in 2015. He was a high school soccer player with a previous history of a bilateral L5 lumbar spondylolysis in 2014. The patient refrained from soccer and wore a brace for six months. Two months after restarting soccer, he again complained of low back pain. After 1 year, a lumbar spine computed tomography revealed the bone union of the spondylolysis. At his first visit to our hospital, his general and neurological conditions were normal and laboratory data were within the normal range. Sacral coronal magnetic resonance imaging (MRI) of the left sacral ala revealed an oblique lineal signal void surrounding bone marrow edema. Based on his symptoms, sports history, and MRI, he was diagnosed with a sacral stress fracture. He again refrained from soccer; his low back pain soon improved, and, after 1 year, the abnormal signal change had disappeared on sacral MRI. Recurrent low back pain case caused by a sacral stress fracture occurring after the bone union of lumbar spondylolysis is uncommon

Direction-sensitive dark matter search results in a surface laboratory

We developed a three-dimensional gaseous tracking device and performed a direction-sensitive dark matter search in a surface laboratory. By using 150 Torr carbon-tetrafluoride (CF_4 gas), we obtained a sky map drawn with the recoil directions of the carbon and fluorine nuclei, and set the first limit on the spin-dependent WIMP (Weakly Interacting Massive Particles)-proton cross section by a direction-sensitive method. Thus, we showed that a WIMP-search experiment with a gaseous tracking device can actually set limits. Furthermore, we demonstrated that this method will potentially play a certain role in revealing the nature of dark matter when a low-background large-volume detector is developed.Comment: 9 figures, accepted for publication in Phys. Lett.