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
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. >
137007144
Front-end ASIC for a GEM based time projection chamber
A time projection chamber for experiments with the laser electron gamma source is being developed. It is composed of a can and a single-ended, dual-stage gas electron multiplier, with associated anode plane pixellated into about 8000 pads. The front-end electronics must provide energy, timing, and address information from those pads involved in measuring each track. For center of gravity determination this information must be sampled from the above-threshold pad and from the two adjacent ones. An efficient scheme for readout of the /spl ap/8000 front-end channels between each measurement cycle is also required. A 32-channel front-end application-specific integrated circuit has been developed to serve this detector. Fabricated in 0.25 /spl mu/m CMOS technology, it dissipates 41 mW. Each channel implements a low noise charge preamplifier with continuous reset of new concept, shaping amplifier with bandgap referenced baseline stabilizer, single threshold discriminator, dual-phase peak detector, timing detector, and logic for neighbor enabling. The readout process is based on token passing and flag.
117514206
MWPC with highly segmented cathode pad readout
Experiments being conducted with high energy heavy ion beams at Brookhaven National Laboratory and at CERN have shown the importance of developing position sensitive detectors capable of handling events with high multiplicity in environments of high track density as will also be the case in future high luminosity colliders like SSC and RHIC. In addition, these detectors are required to have a dynamic range wide enough to detect minimum ionizing particles and heavy ions like oxygen or silicon. We present here a description of work being done on a prototype of such a detector at BNL. Results from a similar counter are also presented in this Conference. The ''pad chamber'' is a detector with a cathode area subdivided into a very large number of pixel-like elements such that a charged particle traversing the detector at normal incidence leaves an induced charge on a few localized pads. The pads are interconnected by a resistive strip, and readout amplifiers are connected to the resistive strip at appropriate, carefully determined spacings. The pattern of tracks in a multi-hit event is easily recognized, and a centroid-finding readout system allows position determination to a small fraction of the basic cell size. 5 refs., 9 figs.
109473699
Gas proportional detectors with interpolating cathode pad readout for high track multiplicities
New techniques for position encoding in very high rate particle and photon detectors will be required in experiments planned for future particle accelerators such as the Superconducting Super Collider and new, high intensity, synchrotron sources. Studies of two interpolating cathode ``pad`` readout systems are described in this thesis. They are well suited for high multiplicity, two dimensional unambiguous position sensitive detection of minimum ionizing particles and heavy ions as well as detection of x-rays at high counting rates. One of the readout systems uses subdivided rows of pads interconnected by resistive strips as the cathode of a multiwire proportional chamber (MWPC). A position resolution of less than 100 {mu}m rms, for 5.4 keV x-rays, and differential non-linearity of 12% have been achieved. Low mass ({approximately}0.6% of a radiation length) detector construction techniques have been developed. The second readout system uses rows of chevron shaped cathode pads to perform geometrical charge division. Position resolution (FWHM) of about 1% of the readout spacing and differential non-linearity of 10% for 5.4 keV x-rays have been achieved. A review of other interpolating methods is included. Low mass cathode construction techniques are described. In conclusion, applications and future developments are discussed. 54 refs.
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.