We have developed a real‐time system to monitor high‐energy cosmic rays for use in space weather forecasting and specification. Neutron monitors and muon detectors are used for our system, making it ...possible to observe cosmic rays with dual energy range observations. In large solar energetic particle (SEP) events, the ground level enhancement (GLE) can provide the earliest alert for the onset of the SEP event. The loss cone precursor anisotropy predicts the arrival of interplanetary shocks and the associated interplanetary coronal mass ejections (ICMEs), while the occurrence of bidirectional cosmic ray streaming indicates that Earth is within a large ICME. This article describes a set of real‐time Web displays that clearly show the appearance of the GLE, loss cone precursor, and other space weather phenomena related to cosmic rays.
We analyze a loss cone anisotropy observed by a ground‐based muon hodoscope at Mt. Norikura in Japan for 7 hours preceding the arrival of an interplanetary shock at Earth on October 28, 2003. Best ...fitting a model to the observed anisotropy suggests that the loss cone in this event has a rather broad pitch‐angle distribution with a half‐width about 50° from the IMF. According to numerical simulations of high‐energy particle transport across the shock, this implies that the shock is a “quasi‐parallel” shock in which the angle between the magnetic field and the shock normal is only 6°. It is also suggested that the lead‐time of this precursor is almost independent of the rigidity and about 4 hour at both 30 GV for muon detectors and 10 GV for neutron monitors.
The amplitude of the Compton-Getting (CG) anisotropy contains the power-law index of the cosmic-ray energy spectrum. Based on this relation and using the Tibet air shower array data, we measure the ...cosmic-ray spectral index to be -3.03 plus or minus 0.55 sub(stat) plus or minus <0.62 sub(syst) between 6 and 40 TeV, consistent with -2.7 from direct energy spectrum measurements. Potentially, this CG anisotropy analysis can be utilized to confirm the astrophysical origin of the "knee" against models for nonstandard hadronic interactions in the atmosphere.
We have analyzed the yearly averaged sidereal daily variations in the count rates of 46 underground muon telescopes by fitting Gaussian functions to the data. These functions represent the loss cone ...and tail‐in anisotropies of the sidereal anisotropies model proposed by Nagashima et al. l995a, b. The underground muon telescopes cover the median rigidity range 143–1400 GV and the viewing latitude range 73°N–76°S. From the Gaussian amplitudes and positions we have confirmed that the tail‐in anisotropy is more prominent in the southern hemisphere with its reference axis located at declination (δ) ∼14°S and right ascension (α) ∼4.7 sidereal hours. The tail‐in anisotropy is asymmetric about its reference axis, and the observed time of maximum intensity depends on the viewing latitude of the underground muon telescopes. We also find that the declination of the reference axis may be related to the rigidity of the cosmic rays. We show that the loss cone anisotropy is symmetric and has a reference axis located on the celestial equator (δ ∼ 0°) and α ∼ 13 sidereal hours. We have used the parameters of the Gaussian fits to devise an empirical model of the sidereal anisotropies. The model implies that the above characteristics of the anisotropies can explain the observed north‐south asymmetry in the amplitude of the sidereal diurnal variation. Furthermore, we find that the anisotropies should cause the phase of the sidereal semidiurnal variation of cosmic rays to be observed at later times from the northern hemisphere compared to observations from the southern hemisphere. We present these results and discuss them in relation to current models of the heliosphere.
We investigated seasonal variations in the soil microbial biomass N content (MBN) and the soil neutral sugar composition from April 1995 to September 1996 in cattle-grazed pasture in a Japanese ...Andisol. MBN showed seasonal variation, gradually increasing from April to August, and decreasing rapidly by the end of August when soil moisture content decreased. Soil inorganic-N increased after fertilization and cattle pasturage. Seasonal variations in seven types of neutral sugar-C contents in the soil were observed. However, the trends in seasonal variation for sugars derived from plant materials were different from one another and from those derived from microbial products. Seasonal variation trends in soil neutral sugar-C were similar to that of MBN, with a sharp decrease in midsummer and a subsequent increase in autumn probably due to dence pasture plant growth. Furthermore, galactose-C (Gal), rhamnose-C (Rham) and ribose-C (Rib) that originated mainly from microbes showed positive correlations with MBN, but the other forms of soil neutral sugar-C did not. It was concluded that the composition of the soil organic matter accumulated in grassland varied seasonally, and that these seasonal variations can be investigated by MBN or by soil neutral sugar composition.
A minor population of blood cells deficient of glycosylphosphatidylinositol (GPI)–anchored membrane proteins is often detected in patients with aplastic anemia (AA), though the clinical significance ...of such paroxysmal nocturnal hemoglobinuria (PNH)–type cells remains unclear. To clarify this issue, we studied 164 patients with myelodysplastic syndrome (MDS) for the presence of CD55−CD59− granulocytes and red blood cells using sensitive flow cytometry. Among the different subgroups of MDS, a significant increase (ie, at least 0.003%) of PNH-type cells was detected in 21 of 119 patients with refractory anemia (RA); this frequency (17.6%) of RA patients with increased PNH-type cells (PNH+ patients) was much lower than what we previously reported (52.0%) for AA patients. PNH+ RA patients had distinct clinical features compared with RA patients without increased PNH-type cells (PNH− patients), such as less pronounced morphologic abnormality of blood cells, more severe thrombocytopenia, lower rates of karyotypic abnormality (4.8% vs 32.8%) and of progression to acute leukemia (0% vs 6.2%), higher probability of response to cyclosporine therapy (77.8% vs 0%), and higher incidence of HLA-DR15 (90.5% vs 18.5%). These data indicate that the presence of a minor population of PNH-type cells suggests a benign type of bone marrow failure, probably caused by an immunologic mechanism. To choose an appropriate therapy, peripheral blood should be tested using sensitive flow cytometry for the presence of PNH-type cells in all patients with bone marrow failure before treatment.
The energy spectrum of cosmic rays around the knee measured by Tibet air-shower experiment is summarized and its characteristic features are discussed under two possible scenarios. The result of ...Tibet experiment measured over wide range of 1014 -1017 eV with high statistics provided details of the knee at the energy around 4×1015 eV. The study of the chemical composition based on measurements of proton and helium spectra obtained from air-shower core detection indicates the dominance of heavy nuclei around the knee. Such feature can be explained either by contribution of nearby sources with source composition dominated by heavy nuclei or by nonlinear effect in diffusive shock acceleration mechanism.
We present an updated all-particle energy spectrum of primary cosmic rays in a wide range from image to image eV using image events collected from 2000 November through 2004 October by the Tibet-III ...air-shower array located 4300 m above sea level (an atmospheric depth of 606 g cm(-2)). The size spectrum exhibits a sharp knee at a corresponding primary energy around 4 PeV. This work uses increased statistics and new simulation calculations for the analysis. We discuss our extensive Monte Carlo calculations and the model dependencies involved in the final result, assuming interaction models QGSJET01c and SIBYLL2.1, and heavy dominant (HD) and proton dominant (PD) primary composition models. Pure proton and pure iron primary models are also examined as extreme cases. A detector simulation was also performed to improve our accuracy in determining the size of the air showers and the energy of the primary particle. We confirmed that the all-particle energy spectra obtained under various plausible model parameters are not significantly different from each other, which was the expected result given the characteristics of the experiment at high altitude, where the air showers of the primary energy around the knee reach near-maximum development, with their features dominated by electromagnetic components, leading to a weak dependence on the interaction model or the primary mass. This is the highest statistical and the best systematics-controlled measurement covering the widest energy range around the knee energy region.
Issue Title: The Multi-Messenger Approach to High-Energy Gamma-Ray Sources: Third Workshop on the Nature of Unidentified High-Energy Sources We propose to build a large water-Cherenkov-type ...muon-detector array (Tibet MD array) around the 37000 m^sup 2^ Tibet air shower array (Tibet AS array) already constructed at 4300 m above sea level in Tibet, China. Each muon detector is a waterproof concrete pool, 6 m wide × 6 m long × 1.5 m deep in size, equipped with a 20 inch-in-diameter PMT. The Tibet MD array consists of 240 muon detectors set up 2.5 m underground. Its total effective area will be 8640 m^sup 2^ for muon detection. The Tibet MD array will significantly improve gamma-ray sensitivity of the Tibet AS array in the 100 TeV region (10-1000 TeV) by means of gamma/hadron separation based on counting the number of muons accompanying an air shower. The Tibet AS+MD array will have the sensitivity to gamma rays in the 100 TeV region by an order of magnitude better than any other previous existing detectors in the world. PUBLICATION ABSTRACT
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