Time to amplitude converter

Fig. 3.1. Schematic diagram of a TCSPC setup. Using a fast timing device (e.g., time-to-amplitude-converter) the time is measured between the excitation pulse and the detection of a photon. By repeating this procedure many times a decay curve is measured. TAC time to amplitude convertor, MCA multi channel analyzer, PC personal computer. 

Section 6.2.2) as follows because the excited-state lifetime is generally of a few nanoseconds, a single-channel analyzer is used in conjunction with a time-to-amplitude converter to process only the photons that are detected at times longer than 1 ns after the excitation pulse. 

From the standpoint of time domain (e.g., time-correlated single photon counting) experiments the method of modelocking is not too crucial as long as the pulse jitter is modest (some picoseconds), and the pulse intensity doesn t vary too much if the time-to-amplitude converter is being started instead of stopped by the excitation pulse, it may be immaterial. From the standpoint of the frequency domain, however, the... 

The discriminator produces an output pulse with a fixed shape (generally square) and size when the input signal crosses a reference. Discriminators usually have multiple identical output signals. The logic pulses can be sent to a scaler that simply counts the number of pulses, to a count rate meter to monitor radiation rates or doses, and to a time-to-amplitude converter (TAC) to measure the relative times of arrival of two or more logic signals. 

Figure 1. Block diagram of single-photon time-correlation apparatus from Barker and Weston 11 HV, high-voltage supplies L, lamp PI, photomultiplier M, monochromator FURN, furnace C, sample cell LP, light pipe F, interference filter P2, photomultiplier AMP, amplifier DISCI, discriminator D1SC2, discriminator T-S, timer scaler DL, delay line TAC, time-to-amplitude converter BA, biased amplifier MCPHA, multichannel pulse-height analyzer TTY, teletype printer and paper-tape punch REC, strip-chart recorder.

Coleman, P.G., Griffith, T.C. and Heyland, G.R. (1974). The analysis of data obtained with time to amplitude converter and multichannel analyser systems. Appl. Phys. 5 223-230. 

Figure 3.21 Schematic showing the typical components of a time-correlated single photon counting experiment PD, photodiode TAC, time-to-amplitude converter MCA, multichannel analyzer MC, PMT, photomultiplier tube...

Fig. 5. The schematic diagram of the pulsing system and the ion beam pulse radiolysis system with an optical emission spectroscopy. PMT denotes photomultiplier tube HV, high voltage supply CFD, constant fraction discriminator TAC, time to amplitude converter and PH A, pulse height analyzer. From Ref. 36...

Figure 3.3 (a) standard positron lifetime set-up PM TUBE photomultiplier tube/ scintillator assembly CF DIFF DISC constant fraction differential discriminator DELAY delay box or fixed length of 50Q cable TAC time-to-amplitude converter MCA multichannel analyser, (b) digital version of (a) [Rytsola etal, preprint, 2001]. 

Time-correlated single photon counting A technique for the measurement of the time histogram of a sequence of photons with respect to a periodic event, e.g. a flash from a repetitive nanosecond lamp or a CW operated laser mode-locked laser). The essential part is a time-to-amplitude-converter (TAG) which transforms the arrival time between a start and a stop pulse into a voltage. Sometimes called single photon timing. 

The classical time measuring system, the combination of a Time-to-Amplitude Converter (TAG) and a Multi-Channel-Analyser (MCA) has a much longer deadtime of the order of 20 psec. 

We use single photon counting i.e. no more than one fluorescence photon is received by the photomultiplier for one excitation pulse. On receiving this photon, the cathode of the PM ejects a photoelectron which is amplified in order to produce an electric pulse at the anode. This pulse is sent to the start inject of a time to amplitude converter (TAG) at a time tj, which is compared with the time tj at which the belayed reference pulse is received by the stop input. At its output, the TAG sends a pulse whose amplitude is proportional to tj — t, to an analogic-digital... 

For the analysis in which the correlation function has to be recorded in the ns regime a typical Flanbury Brown and Twiss [18] set up. Figure 4.4 shows a confocal setup (discussed later) in combination with a beam splitter and a time to amplitude converter (TAG). Since both pathways for the emitted photons acting as start or stop for the time amplitude converter (TAG) are equivalent the correlation curves registered in a multichannel analyzer (MGA) are symmetric relative to 0 time. 

A time-to-amplitude converter (TAC) system was also employed to measure fluorescence decays without the microscope. Then, the fluorescence decay and the fluorescence lifetime were obtained precisely with the microchannel-plate photomultiplier (MCP-PM) as detection. The time resolution of the lifetime was determined, using a convolution method, to be 10ps. 

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