Stop rate

Figure 5.7 Depth dependence of cosmogenic 3He in a drilled core in Haleakala volcano. The diagram shows a very large deviation from an exponential depth dependence (i.e., mean absorption free path / = 165gcnT2) below 170gcnT2. The curve that yields a better fit to the experimental points is a combination of a simple exponential and the effect of muon-produced 3He via 6Li(n, a)3H. The dashed line is the assumed depth dependence of the muon stopping rate. After Kurz (1986).

We now have the opportunity to perform a laser resonance experiment to measure the Lamb shift in muonic hydrogen. Taking into account the muon stop rate, entrance detector efficiency, long-lived metastable 2S population, laser transition probability, solid angles and detection efficiency of the X-ray detector we estimate our event rate on resonance to be 9 events per hour. 

The setup shown in Fig. 2.13 is often complemented by passive delay lines in the detector and reference channels, by rate meters that display the start and stop rates, and by a suitable computer interface for data readout. 

Fig. 5.60 Pulse-by-pulse multiplexing (left) and pulse group multiplexing (right). Pulse-bypulse multiplexing reduces the effective TAC stop rate in proportion to the number of lasers multiplexed...

In praetiee the distortion can be minimised in the same way as classic pile-up, i.e. by maximising the signal repetition rate, or, more exactly, maximising the TAG stop rate. The signal repetition rate should be as high as possible, and the setup should avoid frequency division in the reference channel and pulse-by-pulse multiplexing with a common stop pulse (see Sect. 5.5.8, page 117). 

Sulphuric acid method. Place 20 g. of commercial cycZohexanol and 0-6 ml. of concentrated sulphuric acid in a 150 or 200 ml. round-bottomed or bolt head flask, add 2-3 chips of porous porcelain, and mix well. Fit the flask with a fractionating column, a Liebig condenser, adapter and filter flask receiver as in Section 111,10 (1). Heat the flask in an air bath (Fig. II, 5, 3) at such a rate that the temperature at the top of the column does not rise above 90° alternatively, an oil bath, heated to a temperature of 130-140°, may be used. Stop the distillation when only a small residue remains and the odour of sulphur dioxide is apparent. Transfer the distillate to a small separatory funnel. 

This acid mixture may be prepared (compare Section 11,49, 1) by placing 120 g. (37-5 ml.) of bromine and 130 g. of crushed ice in a 500 ml. flask, cooling the latter in ice, and passing sulphur dioxide (from a siphon of the liquefied gas) into the bromine layer at such a rate that the gas is completely absorb. The flask is shaken occasionally, and the flow of gas is stopped inunediately the red colour due to free bromine has disappeared the mixture will then have a yellow colour. The resulting acid mixture is equivalent to 260 g. of 48 per cent, hydrobromio acid to which 75 g. of concentrated sulphuric acid have been added it need not be dis. tilled for the preparation of n-butyl bromide. 

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