The Fast RICH

It would clearly be desirable for these rare i)roc( sses to hav( a gt)od hadronic particle identification system capable of performing high quality separation iq) to about 4.0 GeV/c in the forward direction. 

The Fast RICH was proposed some time ago in connection with the design of a detector for the high-luminosity symmetric B Factory at PSI [10]. The distinguishing feature of a Fast RICH is the use of fast photon detectors with j)ad readout to provide the position of the imaged Cerenkov photons. During the past f( w years, an active R S D program has been underway to imderstand the feature s of these dendees and to characterize their performance [3.  

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Figure 4.5. Schematic longitudinal view of the Fast RICH in the PEP-II detector.

Tests of a small pad chamber with vacuum-deposited Csl or CsI-f-TMAE reflective cathodes have confirmed the expected fast and stable single photon response, but tlie quantum efficiency was only about 50% of the expected value. This loss is attributed to long air exposure of the < athode pads while the wires were being strung. Chambers with reflective solid jihotocathodes developed for the Fast RICH prototype are designed to allow fast chamber assembly with minimum air exposure of the cathode. Beam tests of these chambers is expected to begin in fall 1993 [13]. 

The Fast RICH with a liquid radiator is a promising development that meets the performance requirements for a PEP-II detector rather well. R D results to date with cosmic rays and TEA photon detectors are encouraging. Additional R S D now under way should soon indicate whether the promise of this approach can be realized in practice. 

See, in partindar, the work of the FAST RICH group at CERN as discussed in R. Arnold et ai, Niicl. Instr. Meth. A314, 466 (1992) and J. Seguinot et al., NiicL Instr. Meth. A297, 133 (1990). 

Tlie primary system chosen, the Fast RICH, is ])erhaps the closest to a ch monstration of viability among the j otential systems. Wb have benefited from the extensive experience of members of the European Fast RICH Collaboration in dev( loping the conceptual design and the cost estimate. Local expc iii iice witli tin SLD CHID is, of course, particularly relevant. 

At PicArsn (Ref 19), the fast neutron activation approach for detection of expls in suitcases was extended to the activation of both nitrogen and oxygen using two 7-ray detector stations in sequence. After 14 MeV neutron irradiation, the baggage is first monitored for 6.1 MeV 7-rays from the l60(n,p),6N reaction (7.5 sec half-life), followed by measurement of the 10 min 13N. Because expls are also rich in oxygen and have characteristic ratios of N/O, it was felt that this approach would increase the probability of detection with a corresponding decrease in the false alarm rate... 

Figure 2a reveals that the conversion of RBr increases with increasing the amount of water up to the amount of water being 3 mL, then it declines. Note that the sharp increase of the conversion curves is due to the fast difiusion of RBr from the organic phase to the catalyst-rich liquid phase where only part of RBr reacts with QOAc. 

The cell walls of mycobacteria contain three structures peptidoglycan, an arabinogalactan polysaccharide and long chain hydroxy fatty acids (mycolic acids) which are all covalently linked. Additional non-covalently attached lipid components found in the wall include glycolipids, various phospholipids and waxes. The lipid-rich nature of the mycobacterial wall is responsible for the characteristic acid-fastness on staining and serves as a penetration barrier to many antibiotics. Isoniazid and ethambutol have long been known as specific antimycobacterial agents but their mechanisms of action have only recently become more clearly understood. 

In microphase-separated systems, ESR spectra may consist of a superposition of two contributions, from nitroxides in both fast and slow-tumbling regimes. Such spectra provide evidence for the presence of two types of domains with different dynamics and transition temperatures. This case was detected for a HAS-derived nitroxide radical in heterophasic polyfacrylonitrile-butadiene-styrene) (ABS) as shown in Figure 5, the fast and slow components in the ESR spectrum measured represent nitroxide radicals located in butadiene-rich (B-rich) and styrene/acrylonitrile-rich (SAN-rich) domains, respectively [40]. These two components were determined by deconvoluting the ESR spectrum of HAS-NO measured at 300 K. 

Figure 5 Dynamically slow and fast ESR spectra of HAS-NO at 300 K from the SAN-rich and B-rich regions of ABS, respectively.

Ca2+ sensing by 1 can be understood by considering a PET process originating in the Ca2+-free tetracarboxylate receptor and the linearly fused tricyclic system. The rapidity of the process may be ascribed to the low oxidation potential of the electron rich alkoxyaniline donor and to the short distance of separation between the two transfer components. The minimal separation arranged by a virtual spacer of zero carbon atoms is worthy of note. A low level of luminescence is seen owing to the fast PET. 

A fast-start capability is a key requirement for a compact fuel processor, especially crucial for specific cases such as on-board automotive application. A possible means for the fast start-up of an ATR reactor is starting by feeding to the reactor a mixture with an O2 C molar ratio typical of a rich combustion. The goal of this mode is to raise the reactor temperature quickly and simultaneously avoid catalyst oxidation. Then the reactor will move to the ATR mode through the addition of steam and by decreasing the 02 C feed ratio to the desired value. 

For increased reaction rate, the zone of reaction narrows, and in the limit, for an infinitely fast reaction, becomes a boundary surface between the A-rich and... 

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