118633745
Type II Radio Emission and Solar Particle Observations
The 28 October 2003 flare gave us the unique opportunity to compare the acceleration time of high-energy protons with the escaping time of those particles which have been measured onboard spacecraft and by neutron monitors network as GLE event. High-energy emission time scale and shock wave height and velocity time dependencies were also studied.
119107919
GAMMA-RAY BURST LUMINOSITY RELATIONS: TWO-DIMENSIONAL VERSUS THREE-DIMENSIONAL CORRELATIONS
The large scatters of luminosity relations of gamma-ray bursts (GRBs) have been one of the most important reasons that prevent the extensive applications of GRBs in cosmology. In this paper, we extend the two-dimensional (2D) luminosity relations with tau(lag), V, E(peak), and tau(RT) as the luminosity indicators to three dimensions (3D) using the same set of luminosity indicators to explore the possibility of decreasing the intrinsic scatters. We find that, for the 3D luminosity relations between the luminosity and an energy scale (E(peak)) and a timescale (tau(lag) or tau(RT)), their intrinsic scatters are considerably smaller than those of corresponding 2D luminosity relations. Enlightened by the result and the definition of the luminosity (energy released in units of time), we discussed possible reasons behind this result, which may give us helpful suggestions on seeking more precise luminosity relations for GRBs in the future.
117246893
Standardization, Distance, Host Galaxy Extinction of Type Ia Supernova and Hubble Diagram from the Flux Ratio Method
In this paper we generalize the flux ratio method Bailey et al. (2009) to the case of two luminosity indicators and search the optimal luminosity-flux ratio relations on a set of spectra whose phases are around not only the date of bright light but also other time. With these relations, a new method is proposed to constrain the host galaxy extinction of SN Ia and its distance. It is first applied to the low redshift supernovas and then to the high redshift ones. The results of the low redshift supernovas indicate that the flux ratio method can indeed give well constraint on the host galaxy extinction parameter E(B-V), but weaker constraints on R_{V}. The high redshift supernova spectra are processed by the same method as the low redshift ones besides some differences due to their high redshift. Among 16 high redshift supernovas, 15 are fitted very well except 03D1gt. Based on these distances, Hubble diagram is drew and the contents of the Universe are analyzed. It supports an acceleration behavior in the late Universe. Therefore, the flux ratio method can give constraints on the host galaxy extinction and supernova distance independently. We believe, through further studies, it may provide a precise tool to probe the acceleration of the Universe than before.
119271545
New constraints on anisotropic rotation of CMB polarization
The coupling of a scalar field to electromagnetic field via the Chern-Simons term will rotate the polarization directions of the cosmic microwave background radiation. The rotation angle which relies on the distribution of the scalar field on the CMB sky is direction dependent. Such anisotropies will give rise to new distortions to the power spectra of CMB polarization and it can be used to probe the detailed physics of the scalar field. In this paper we use the updated observational data to constrain the anisotropic rotation angle in a model independent way. We find that the dominant effect of the anisotropic rotation on CMB comes from its variance and it is constrained tightly by the current data.
195862381
Study of GEM characteristics for application in a MicroTPC
The Gas Electron Multiplier (GEM) may provide a convenient method for obtaining significant electron multiplication over large detector areas. An important potential application of the GEM is for readout of microTPCs. We are conducting a study of a multi-GEM structure with particular emphasis on the following characteristics: gain uniformity/stability, ion feedback and position readout. In particular, we present the first experimental results of interpolating anode pad readout. Initial results provide encouragement that the GEM application in microTPCs may be realized.
195841173
Investigation Of Chevron Cathode Pads For Position Encoding In Very High Rate, Gas Proportional Chambers
2492346
The linearity performance of a two-dimensional, X-ray proportional chamber with 0.58 mm anode wire spacing
A method of construction of multiwire chambers has been developed which yields X-ray images with very small non-linearity, in particular that due to anode wire modulation. The technique requires an absorption region in the detector, with the anode and upper cathode wires, which are parallel to one another, in registration with each other. Studies show that the strength of the electric field in the drift region determines the degree of anode wire modulation and, under specific conditions, modulation is halved in period and significantly reduced in amplitude. New interpolating cathodes have been developed to read out position in the other axis, along the anode wire direction. Position resolution in both axes-between 100-150 /spl mu/m FWHM has been achieved. Two-dimensional images of small objects have been taken which show unprecedented linearity. >
56431570
Results of the NASA Space Radiation Laboratory Beam Studies Program at BNL
The NASA Space Radiation Laboratory (NSRL) was constructed in collaboration with NASA for the purpose of performing radiation effect studies for the NASA space program. The NSRL makes use of heavy ions in the range of 0.05 to 3 GeV/n slow extracted from BNL’s AGS Booster. The purpose of the NSRL Beam Studies Program is to develop a clear understanding of the beams delivered to the facility, to fully characterize those beams, and to develop new capabilities in the interest of understanding the radiation environment in space. In this report we will describe the first results from this program.
26771610
A Novel 2-D Position Sensitive Silicon Detector With Micron Resolution for Heavy Ion Tracking
A new 2-D position sensitive silicon detector for tracking of energetic heavy ions is under development in a program to study the radiation effect within a single human cell. The detector is based on a concept of interleaved pixel electrodes arranged in a projective 2-D strip readout (stripixel). A fine position resolution in the sub-micron range can be achieved by determining the centroid of the charge collected on pixel electrodes with a granularity in the range of 10 mum. Beam test results with 1 GeV/n Fe ions have demonstrated an rms position resolution of about 0.5 mum with a 30 mum pixel pitch