122338380
COSMIC RAY MUONS FROM LOW GALACTIC LATITUDE
Occasional spurious tracks are found on photographs taken during routine observations with the 40-inch heavy-liquid bubble chamber (HLBC) at the Argonne National Laboratory (Roe, Sinclair, and Vander Vilde 1964). These tracks are caused by cosmic ray muons, and are rather similar to streaks caused by meteors on photographs of the sky. The HLBC is located at Ν 41°42'03" latitude and W 87°59'24" longitude, and at an altitude of 227.38 meters above sea level. It has a field of view in the form of a strip 50° wide centered on the north-zenith-south meridian. The strip extends from horizon to horizon. As the earth turns, 87 percent of the celestial sphere passes through the field of view. The product of the cross-sectional capture area of the HLBC times its field of view is 1.7 meter2 steradian. Each picture covers the entire field of view and has a sensitive time of six milliseconds. The chamber is ex-
124504029
The search for quarks in terrestrial matter
Abstract Recent experimental searches for physical quarks stopped in terrestrial matter are reviewed and summarized.
122093024
Lorentz deformation and the jet phenomenon. II. Explanation of the nearly constant average jet transverse momentum
It is shown that the jet mechanism derivable from the Lorentz deformation picture leads to a nearly constant average jet transverse momentum. It is pointed out that this is consistent with the high-energy experimental data. It is pointed out further that this result strengthens the physical basis for the minimal time-energy uncertainty combined covariantly with Heisenberg's space-momentum uncertainty relation.
110736009
Analysis of noise characteristics for the active pixels in CMOS image sensors for X-ray imaging
Abstract CMOS image sensors have poorer performance compared to conventional charge coupled devices (CCDs). Since CMOS Active Pixel Sensors (APSs) in general have higher temporal noise, higher dark current, smaller full well charge capacitance, and lower spectral response, they cannot provide the same wide dynamic range and superior signal to noise ratio as CCDs. In view of electronic noise, the main source for the CMOS APS is the pixel, along with other signal processing blocks such as row and column decoder, analog signal processor (ASP), analog-to-digital converter (ADC), and timing and control logic circuitry. Therefore, it is important and necessary to characterize noise of the active pixels in CMOS APSs, and we performed experimental measurements and comparisons with theoretical estimations. To derive noise source of the pixels, we designed and fabricated four types of CMOS active pixels, and each pixel is composed of a photodiode and three MOS transistors. The size of these pixels is 100 μm×100 μm. The test chip was fabricated using ETRI 0.8 μm (2P/2M) standard CMOS process. It was found that the dominant noise in CMOS active pixels is shot noise during integration under normal operating conditions. And, it was also seen that epitaxial type pixels have similar noise level compared to non-epitaxial type, and the noise of diffusion type pixel is larger than for a well type pixel on the same substrate type.
116955268
Lorentz Group in Ray and Polarization Optics
While the Lorentz group serves as the basic language for Einstein's special theory of relativity, it is turning out to be the basic mathematical instrument in optical sciences, particularly in ray optics and polarization optics. The beam transfer matrix, commonly called the $ABCD$ matrix, is shown to be a two-by-two representation of the Lorentz group applicable to the three-dimensional space-time consisting of two space and one time dimensions. The Jones matrix applicable to polarization states turns out to be the two-by-two representations of the Lorentz group applicable to the four-dimensional space-time consisting of three space and one time dimensions. The four-by-four Mueller matrix applicable to the Stokes parameters as well as the Poincar\'e sphere are both shown to be the representations of the Lorentz group.
121594367
Internal space-time symmetries of particles derivable from periodic systems in optics
While modern optics is largely a physics of harmonic oscillators and two-by-two matrices, it is possible to learn about some hidden properties of the two-by-two matrix from optical systems. Since two-by-two matrices can be divided into three conjugate classes depending on their traces, optical systems force us to establish continuity from one class to another. It is noted that those three classes are equivalent to three different branches of Wigner’s little groups dictating the internal space-time symmetries massive, massless, and imaginary-mass particles. It is shown that the periodic systems in optics can also be described by the same class-based matrix algebra. The optical system allow us to make continuous, but not analytic, transitions from massiv to massless, and massless to imaginary-mass cases.
111325925
Reduction of ripple fields in DC magnet using an auxiliary winding
This paper presents a simple method to achieve 10−6 level of ripple fields in a large current DC magnet which is excited by a power supply of moderate ripple current content (10−4–10−5). A theory of the ripple field in a magnet with an auxiliary winding is derived and the conditions for ripple field reduction are obtained. When the resistance of the auxiliary circuit is much smaller than the reactance of that circuit, the ripple field bucking ratio is proportional to the quality factor of the auxiliary winding. To compare the theory with the experiment, a dipole magnet with an auxiliary winding was used. The auxiliary winding was either short-circuited or loaded with a resistor and the ripple fields were measured with a pickup coil placed in the magnet gap. When the auxiliary winding was short-circuited, a ripple field bucking ratio greater than 40 was achieved with a high output impedance power supply. This experimental result agrees well with the theory, and indicates that an auxiliary winding of a large cross-sectional area, instead of a large turn-number, is desired for an efficient ripple field reduction.