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In the application of semiconductor detectors, the charge-sensitive amplifier is widely used in front-end electronics. The output signal is shaped by a typical exponential decay. Depending on the feedback network, this type of front-end electronics suffers from the ballistic deficit problem, or an increased rate of pulse pile-ups. Moreover, spectroscopy applications require a correction of the pulse-height, while a shortened pulse-width is desirable for high-throughput applications. For both objectives, digital deconvolution of the exponential decay is convenient. With a general method and the signals of our custom charge-sensitive amplifier for cadmium zinc telluride detectors, we show how the transfer function of an amplifier is adapted to an infinite impulse response (IIR) filter. This paper investigates different design methods for an IIR filter in the discrete-time domain and verifies the obtained filter coefficients with respect to the equivalent continuous-time frequency response. Finally, the exponential decay is shaped to a step-like output signal that is exploited by a forward-looking pulse processing.

Cadmium zinc telluride (CdZnTe, CZT) radiation detectors are suitable for a variety of applications, due to their high spatial resolution and spectroscopic energy performance at room temperature. However, state-of-the-art detector systems require high-performance readout electronics. Though an application-specific integrated circuit (ASIC) is an adequate solution for the readout, requirements of high dynamic range and high throughput are not available in any commercial circuit. Consequently, the present study develops the analog front-end electronics with operational amplifiers for an 8x8 pixelated CZT detector. For this purpose, we modeled an electrical equivalent circuit of the CZT detector with the associated charge-sensitive amplifier (CSA). Based on a detailed network analysis, the circuit design is completed by numerical values for various features such as ballistic deficit, charge-to-voltage gain, rise time, and noise level. A verification of the performance is carried out by synthetic detector signals and a pixel detector. The experimental results with the pixel detector assembly and a 22Na radioactive source emphasize the depth dependence of the measured energy. After pulse processing with depth correction based on the fit of the weighting potential, the energy resolution is 2.2% (FWHM) for the 511 keV photopeak.

State of the art detector readout electronics require high-throughput data acquisition (DAQ) systems. In many applications, e. g. for medical imaging, the front-end electronics are set up as separate modules in a distributed DAQ. A standardized interface between the modules and a central data unit is essential. The requirements on such an interface are varied, but demand almost always a high throughput of data. Beyond this challenge, a Gigabit Ethernet interface is predestined for the broad requirements of Systems-on-a-Chip (SoC) up to large-scale DAQ systems. We have implemented an embedded protocol stack for a Field Programmable Gate Array (FPGA) capable of high-throughput data transmission and clock synchronization. A versatile stack architecture for the User Datagram Protocol (UDP) and Internet Control Message Protocol (ICMP) over Internet Protocol (IP) such as Address Resolution Protocol (ARP) as well as Precision Time Protocol (PTP) is presented. With a point-to-point connection to a host in a MicroTCA system we achieved the theoretical maximum data throughput limited by UDP both for 1000BASE-T and 1000BASE-KX links. Furthermore, we show that the random jitter of a synchronous clock over a 1000BASE-T link for a PTP application is below 60 ps.

Using methods of effective field theory, factorized expressions for arbitrary B -> X_u l nu decay distributions in the shape-function region of large hadronic energy and moderate hadronic invariant mass are derived. Large logarithms are resummed at next-to-leading order in renormalization-group improved perturbation theory. The operator product expansion is employed to relate moments of the renormalized shape function with HQET parameters such as m_b, Lambda(bar) and lambda_1 defined in a new physical subtraction scheme. An analytic expression for the asymptotic behavior of the shape function is obtained, which reveals that it is not positive definite. Explicit expressions are presented for the charged-lepton energy spectrum, the hadronic invariant mass distribution, and the spectrum in the hadronic light-cone momentum P_+ = E_H - P_H. A new method for a precision measurement of |V_{ub}| is proposed, which combines good theoretical control with high efficiency and a powerful discrimination against charm background., Comment: 51 pages, 10 figures; minor corrections, version to appear in Nuclear Physics B

Soft-collinear effective theory is used to prove factorization of the B->gamma+l+nu decay amplitude at leading power in Lambda/m_b, including a demonstration of the absence of non-valence Fock states and of the finiteness of the convolution integral in the factorization formula. Large logarithms entering the hard-scattering kernel are resummed by performing a two-step perturbative matching onto the low-energy effective theory, and by solving evolution equations derived from the renormalization properties of the leading-order B-meson light-cone distribution amplitude. As a byproduct, the evolution equation for heavy-collinear current operators in soft-collinear effective theory is derived., Comment: 20 pages, 5 figures; several references added or updated, extended discussion of the new elements of the factorization proof, typo in eq.(6) fixed; version to appear in Phys. Rev. D

The design of a drag-free satellite and its application to measuring tidal interaction of the earth and tesseral harmonics are discussed. Principle areas of discussion are: (1) the feasibility of making geophysical measurements which are not possible with conventional satellites, and (2) design of attitude and translation control systems for spinning vehicle and possible coupling of attitude and translation control for gravity stabilized vehicles.

Minimum fuel attitude control of spacecraft by Pontryagin principle and extended steepest descent method

Satellite attitude control using gyro-telescope structure driven by superconducting actuator

Aeronomy experiment satellite polar orbit, control analysis, and control simulation

Linear and nonlinear attitude control law synthesis for spinning aerospace vehicles, including analog simulation for control designs based on frequency symmetry

Deviation of path of orbiting body calculated from nominal or reference trajectory

Zero gravity satellite concept feasibility and control system design evaluation using air cushion vehicle

Calculation of path deviation of satellite from reference trajectory - perturbation theory

A purely gravitational orbit satellite