ADC chamber

Fig. 2 The steps in the process of thin-layer chromatography that have been instrumentalized and automated to a large degree in the recent past. PMD = Programmed Multiple Development, AMD = Automated Multiple Development, DC-Mat or ADC = Automatic Development Chamber.

More recent chromatogram chambers - e.g. the AMD system (Fig. 11) - only possess a small observation window and this can, if necessary, be covered with a black cloth. Development in the DC-Mat (Fig. 12) or the ADC (Fig. 13) automatic development chambers is carried out entirely in the dark. 

Figure 12.4. Block diagram of a modem NMR spectrometer. These systems use superconducting magnets that are based on a solenoid of a suitable alloy (e.g., niobium/titanium or niobium/tin) immersed in a dewar of liquid helium. The extremely low temperature of the magnet itself (4.2 K) is well insulated from the sample chamber in the center of the magnet bore. The probe in which the sample is housed usually incorporates accurate temperature control over the range typically of 4 to 40°C for biological samples. The rf coil in the probe is connected in turn to a preamplifier, receiver circuitry, analog-to-digital converter (ADC), and a computer for data collection.

The chamber type is noted N for normal chamber (or DT-N for double-trough chamber, CAMAG), H for horizontal chamber (e.g. 5x5 cm, DESAGA), DC-MAT for automatic development chamber (Baron), ADC for automatic developing chamber (CAMAG), etc. 

Commercially available systems integrate in a single unit the high-voltage power supply, amplifier, analog-to-digital converter (ADC) and multichannel analyzer with the counting chamber, detector, and preamplifier, as shown in Fig. 8.8. 

Similar Automatic Developing Chambers (ADC) for either 20 X 10 or 20 X 20 cm plates are available from Camag. The ADC was used to separate saturated and unsaturated oligogalacturonic acids by multiple development with 1-propanol-water mixtures on silica gel 60 plates (Dongowski, 1997). 

With the increasing number of channels of electronic readout required for these detectors, Fastbus modules have proven to be an economical and reliable solution. The beam-defining microstrips, veto scintillators and the calorimeter blocks are all read out in Fastbus ADC s. In addition, the readout of the drift chambers is now done with Fastbus TDC s which have operated reliably during this year s runs. 

For the recently completed E788 experiment (see section IV), one FASTBUS crate was used. The crate contained 320 channels of fast single-hit TDC s, 384 channels of ADC s, and 384 channels of multi-hit TDC s, all provided by CMU. (CMU also provided half of the required constant fraction discriminators.) Most out-of-beam detectors were instrumented in FASTBUS, while the in-beam hodoscopes, all drift chambers, and a few auxiliary detectors were based in CAMAC. 

For the H-particle searches, nearly all signals will be processed through three FASTBUS crates. The only elements not planned for FASTBUS processing are those for which FASTBUS modules are either not yet available or not cost effective, The H-purticle experiment has about 700 channels of ADCs, 700 channels of single-hit TDC information, and another 2000 channels of multi-hit TDC information (mainly for drift chamber data). CMU will provide nearly one-third of the necessary FASTBUS modules. 

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