Amplifier and Preamplifier

TMC 256-channel analyzer with 212 pulse neutron logic AID linear amplifier and preamplifier BF3 detector. 

The pump lasers were designed and built at LLNL. Two laser cavity configurations are employed. Two "L" shaped cavities run at the full system repetition rate of 26 kHz, producing 40-50 W per laser. They pump the DM0 and preamplifier dye cells. Four "Z" cavity lasers run at 13 kHz, each producing between 60-80 W. They are interleaved in the power amplifier dye cell to produce an effective 26 kHz repetition rate. Flashlamps were used to pump the frequency-doubled YAG lasers as diode-pumps were much more expensive at the time the Keck LGS was designed. In addition, high wavefront quality is not required... 

Adjustable Workbench (PAW) instrument assembly. The SH shown in Figs. 3.15 and 3.16 contains the electromechanical transducer (mounted in the center), the main and reference Co/Rh sources, multilayered radiation shields, detectors and their preamplifiers and main (linear) amplifiers, and a contact plate and sensor. The contact plate and contact sensor are used in conjunction with the IDD to apply a small preload when it places the SH holding it firmly against the target. The electronics board contains power supplies/conditioners, the dedicated CPU, different kinds of memory, firmware, and associated circuitry for instrument control and data processing. The SH of the miniaturized Mossbauer spectrometer MIMOS II has the dimensions (5 x 5.5 x 9.5) cm and weighs only ca. 400 g. Both 14.4 keV y-rays and 6.4 keV Fe X-rays are detected simultaneously by four Si-PIN diodes. The mass of the electronics board is about 90 g [36],... 

The molecular sensitivities of the first and second generations of the bDNA assays were limited by nonspecific hybridization between the amplification probes and other nucleic acids. Short regions of hybridization between any of the probes constituting the amplification system, (preamplifier, amplifier, and labeled probe) and any nontarget nucleic acid sequence leads to amplification of the background signal. Capture probes, capture extenders, and sample nucleic acid are all sources of this background hybridization (Collins et al 1997). 

Fig. 13. Three types of optical amplifier as distinguished by their location in a network (a) Postamplifier (booster), (b) in-line amplifier, and (c) optical preamplifier. (From. /. Aitgfc)...

The optical source is a diode laser and fiber-emitter and fiber-detector coupling is accomplished using standard optical fiber connectors. The detector is a PIN photodiode connected to a transimpedance preamplifier and the signal is amplified and filtered using a lock-in amplifier that also tunes the modulation frequency of the laser source. The analytical signal is collected and treated by a PC. 

Fig. 14.6. Three-dimensional view of the Teramobile. (L) Laser system Ti Sa oscillator and its Nd YAG pump laser LI), stretcher (L2), regenerative amplifier, multipass preamplifier (L3) and their Nd YAG pump laser (LJ,) Multipass main amplifier (L5) pumped by two Nd YAG units (L6) Compressor (L7). (5), Beam expanding system (C), Power supplies D), Lidar detection system [14]...

In general, the detectors are combined with a preamplifier, an amplifier and a multichannel analyser, in which the pulses are sorted according to their pulse heights. Frequently, the multichannel analyser is operated by a computer and a program for peak search, peak net area calculation, energy calibration and radionuclide identification. 

X-ray spectrometry is generally carried out with Si(Li) detectors. The set-up is similar to that applied to y-ray spectrometry with i-Ge or Ge(Li) detectors cooling of the detector in a cryostat, operation in combination with a preamplifier, an amplifier and a multichannel analyser. The energy resolution is very good, as already mentioned in section 7.6, and makes it possible to distinguish the characteristic X rays of neighbouring elements. Some X-ray emitters that may be used for calibration purposes are listed in Table 7.6. 

The microvolt NMR signal generated in the coil requires amplification prior to detection and digitisation. The first stage is typically 20-30 dB amplification, using a preamplifier whose most important characteristic is the noise figure (NF). This is essentially a measure of the noise added to the signal by the amplifier, and is defined by,... 

In addition to the sample concentration and specific parameters related to the pulse sequence being used, the spectral signal-to-noise ratio (SNR) depends on various components of the spectrometer hardware, in particular the sensitivity of the probe and preamplifier. The SNR can be related to the temperature of the receiver coil ( Tq), its resistance (Rc), the temperature of the sample (Tg), the resistance added to the coil by the sample (i s), and the noise temperature of the amplifier (TA) by the following equation 7... 

Multiwire position readout systems have been used for a number of years with proportional counter detectors (67, 68). Adaptations of this method have proved very successful in imaging applications with MCP s (1, 69-71). A typical arrangement (Figure 10) is described by Knapp (69) and consists of two planes of closely spaced wires. Each wire is 0.1 mm in diameter and individual wires are spaced at 0.2 mm intervals with a gap on the order of the wire spacing between the two planes. The wires in the two planes run orthogonal to each other to permit determination of both the x and y coordinates of an event. Resistors interconnect the wires in each plane and preamplifiers are connected to every eighth wire. Thus, a readout system of 130 + 130 wires, for example, requires 16 + 16 amplifiers. Electron clouds emerging from... 

The gamma ray scintillation spectrometer (Fig. 1) consisted of two single channel analyzers coupled to a common sodium iodide well detector, preamplifier, amplifier and scalers. By setting each analyzer for the appropriate energy the two isotopes were determined. 

Schematic diagrams of the instrumentation for the ANL capacitive flowmeter are given in Fig. 6.20. A 100-kHz sine-wave oscillator, with stable frequency and amplitude controls, was used to pulse the drive electrode. Each sensing electrode was connected to a current-to-voltage converter preamplifier. The preamplifier outputs were bandpass filtered at 100 kHz 5 Hz and amplitude-demodulated. The demodulated signals were amplified and DC-coupled to a first-order low-pass filter to give density signals.

A basic counting system for activation analysis consists of a detector [Ge or Si(Li)], electronics (i.e., preamplifier, amplifier), and a multichannel analyzer (MCA). Modern MCAs do much more than record the data. They are minicomputers or are connected to computers that store and analyze the recorded data. Examples are the ADCAM architecture offered by EG G ORTEC and the Genie-ESP VAX-based Data Acquistion and Analysis System offered by Canberra. 

Because of the high speed of the biased amplifier and the ADC in a TCSPC board, the photon pulses delivered to the ADC need not be broader than 50 to 100 ns. Therefore an extremely high preamplifier gain is not required, and AC coupling can be avoided. The setup can therefore be used up to a count rate of several 10 pulses per second. Examples for pulse height distributions recorded this way are shown in Fig. 6.13, page 227. 

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