Coincidence Circuit Research Articles

Formula omitted] mixing ratios and K conversion coefficients in odd-mass rotational nuclei

The E2 M1 mixing ratios and K conversion coefficients of the first two rotational transitions in 155Gd, 159Tb, 167Er, 173Yb, 175Lu, 179Hf, 181Ta, 185Re and 187Re have been measured. The mixing ratios are determined from angular distributions of gamma rays following Coulomb excitation of the second rotational level. Events belonging only to the decay by cascade of the second rotational level were selected by a coincidence circuit. The same experimental arrangement was used for determination of K conversion coefficients from X-ray and gamma intensity ratios. The agreement between the experimental values of the mixing ratios and the predictions of the rotational model is fair except in the case of 179Hf. The agreement between the experimental and theoretical values of the K conversion coefficients is good. In addition E2/M1 mixing ratios of the 99 and the 141 keV transitions in 195Pt have been determined.

Fast Timing Circuits Using Storage Diodes

A constant-charge pulse shaper has been used as the basic element in two fast timing circuits using photomultipliers. The shaper is based on storage diodes (snap-off diodes) and delivers an approximately constant charge at the output, almost independent of the input current pulse amplitude. These constant-charge pulses are delivered to a tunnel diode, which in the sub-nanosecond range is a charge sensitive device. A coincidence circuit and a time-to-amplitude converter were built and operated with a Co60 source, two plastic scintillators used with 56 AVP tubes, and a slow coincidence discriminator. With a range of 20 mA to 200 mA the coincidence slope was 0.4 nsec for half-amplitude, while the time-to-amplitude converter showed a FWHM of 0.8 nsec on a multichannel analyzer.

Decay Of Eu159

The decay scheme of Eu 159 was investigated by using beta and gamma ray scintillation spectrometers with a fast-slow coincidence circuit. The half-life of Eu 159 was measured as 19.0±0.5 min. Beta rays with end-point energies 2.57±0.05, 2.35±0.05, 1.90±0.05, 1.75±0.05, 1.50±0.05 and 1.0±0.1 MeV, and gamma rays with energies 1500, 1100, 800, 670, 220, 145, 130, 90 and 75 keV were found. On the bases of the experimental results obtained by β-γ, γ-β and γ-γ coincidence measurements, a tentative decay scheme of Eu 159 was proposed. The assignments of the excited levels were made based on the Nilsson model and the systematics in neighbouring odd-N nuclei. The systematic behaviour of low excited levels of gadolinium isotopes and N =95 isotones are discussed.

Image Converter High-Speed Photography with 10^−9–10^−14 sec Time Resolution

The rapid progress in image tube development during recent years has greatly extended the potentialitie of high-speed photography which surpassed even the highly refined oscilloscopic method in time resolution and was made able to record nonrepeated short-duration processes emitting few light quanta. The new situation in high-speed photography has arisen due to the advent of cascaded image converters which have the advantages of ultimate time resolution (down to 10−14 sec), ultimate light efficiency (single light quanta being easily recorded), and high signal-to-noise ratio due to information communication via images consisting of 105–106 resolved elements. The ultra high-speed photography technique using a fast electric field sweep of the electronic image in image converters is called the electron-optical chronography. It has been applied to study spark discharges and secondary emission electron pulses with experimental time resolutions of 10−12–10−13 sec, which greatly exceeded that of conventional streak cameras, Kerr cells, oscilloscopes, and coincidence circuits. The purpose of the present paper is to analyze the fundamental time-resolution limitations of conventional short-time research instruments, to consider the ultimate performance limits of the electron-optical chronography, to describe special image tubes for short-time research, and to review their applications in experimental physics.

An index for magnetic tape — II

In Parts I and II of this paper a method for indexing and addressing magnetic instrumentation tape was described. This communication describes two additional units, one which enables up to twelve positions to be selected automatically from the tape, and another which acts as a repeater to be used at recording stations remote from the tape recorder. By means of digital switches, coincidence circuits may be set up so that at the selected tape position either an electronic pulse or a relay contact closure is obtained-ten four-decimal-digit circuits are provided, and two seven-decimal-digit circuits. The repeater unit gives the same decimal numerical indicating tube display as the main decoding unit, and in addition, has two four digit tape position selectors.

Particle discrimination system for nuclear reaction studies

A solid state system is described which applies the logarithmic method of computing the product E × dE dx to the problem of mass discrimination of charged particles in counter telescopes. The basic conversion circuit uses the emitter-base junction of a transistor as the logarithmic element. Also described are the delay-line clipped amplifiers, zero-crossover coincidence circuits, and single channel pulse height analyzers used with the logarithmic converters.

Printed-Circuit Modular Instrumentation System

A transistorized modular instrumentation system for handling photomultiplier signals from scintillation and/or Čerenkov counters in high energy physics experiments is described. The experimenter has available a multiplicity of operations, such as coincidence determination, gating, amplitude discrimination, multiplexing, mixing, amplification, and pulse-height analysis. System design considerations emphasize direct interchangeability of modules to minimize calibration procedures. Particular emphasis has been placed on the stability and linearity of the amplifying, gating, and mixing circuits, so that 1% pulse-height resolution may be meaningfully achieved. High speed coincidence and gating circuits are available, in which ``pile-up'' effects have been minimized to allow operation at counting rates of up to 10 Mc. In experiments where manual data reduction is feasible, the outputs of the system are displayed via scalers and/or commercial pulse-height analyzers; in more complex experiments, the outputs may be further processed through a digital computer.

Raising the reliability of certain pulsed measuring-device circuits

1. The boundary test method is effective for investigating the reliability of circuits. 2. Voltage Vce can be taken as the boundary parameter for testing the reliability of coincidence and trigger circuits. 3. The optimum corrected values of circuit parameters are shown in Tables 3 and 4. It will be seen from the above Tables than an optimum voltage of −10.5 Vis required for stable operation of the trigger circuit, and of −9.5 V for the coincidence circuit. Therefore, the power-pack voltage was corrected and a dropping resistance inserted in the collector circuit of the stage. 4. It became possible by selecting optimum parameter values to extend the temperature operating range from −40 to +60‡C up to −50 to +80‡C. This raised the probability of a faultless operation of the entire system from 94 to 96%. 5. Tests have shown that the relationship between gradual and sudden failures amounted respectively to 70% and 30%. 6. The circuits which have been investigated above are of practical interest and can be used in designing equipment.

Schnelle koinzidenzstufe mit lawinentransistoren

A fast coincidence circuit using avalanche transistors is described. Excellent results can be obtained even with slow scintillators. In a fast slow coincidence assembly with 32′'Ø×2′' NaI(Tl) crystals and RCA 6810 A photomultipliers a resolving time of 1.6 nsec at nearly 100% coincidence efficiency was realized for the Co60 gamma ray cascade. The circuit is stable and reliable.

Die natürliche grenze der kurzzeitmessung mit verzögerten koinzidenzen

With a fast differential coincidence system the limit of short-time-measurements given by noise in the differential coincidence circuit and the following electronic circuitry, has been determined. The resolving time has been measured as a function of the magnitude of the input pulses for tube diodes and semiconductor diodes, additionally the temperature dependence for semiconductor diodes. The shortest resolving time was measured to be 0.5 ps.

Decay of Eu159

The decay scheme of Eu 159 was investigated by using beta and gamma ray scintillation spectrometers with a fast-slow coincidence circuit. The half-life of Eu 159 was measured as 19.0±0.5 min. Beta rays with end-point energies 2.57±0.05, 2.35±0.05, 1.90±0.05, 1.75±0.05, 1.50±0.05 and 1.0±0.1 MeV, and gamma rays with energies 1500, 1100, 800, 670, 220, 145, 130, 90 and 75 keV were found. On the bases of the experimental results obtained by β-γ, γ-β and γ-γ coincidence measurements, a tentative decay scheme of Eu 159 was proposed. The assignments of the excited levels were made based on the Nilsson model and the systematics in neighbouring odd-N nuclei. The systematic behaviour of low excited levels of gadolinium isotopes and N =95 isotones are discussed.

Determination of coincidence-circuit efficiency by varying the input signal delay

The efficiency of a twofold coincidence circuit for counting simultaneous events is considered in terms of the jitter in the relative timing of its input pulses. Two methods are suggested for analysis of empirical delayed-coincidence curves to infer coincidence efficiency. The first uses no assumptions concerning the detailed form of the jitter distribution. It requires comparison of the maximum coincidence rate with that observed at relative delays twice the resolving time on either side of the optimum. The second method assumes normal jitter distributions and employs as the determinative shape parameter the normalized derivative of the observed delayed-coincidence curve at the sides of the curve near efficiency one-half. Graphs relate this parameter to the efficiency and to the breadth of the jitter distribution. An example is used to illustrate the second method.

A time-to-pulse-height converter with simultaneous random coincidence subtraction

A coincidence circuit capable of simultaneous registration or subtraction of random coincidences is described. The coincidence circuit is based on a time-to-pulse-height converter. The design of a time-to-pulse-height converter for use with NaI(Tl) scintillation counters is given. Random coincidences are counted during the coincidence experiment proper. Systematic errors in determining the number of random coincidences are smaller than 0.5%. The resolving time of the system is 6 ns for the 0.51 MeV line of Na 22. The circuit performs satisfactorily at counting rates up to 50 000 per second.

A fast coincidence circuit using zero-crossed photomultiplier pulses

A coincidence circuit is described which may be used for accurate timing measurements in experiments involving scintillation counters. The circuit is operated by standard pulses which are generated by the crossover point of zero-crossed photomultiplier pulses. The accuracy of the timing information extracted from photomultiplier pulses with a large range of amplitude is given, together with the performance of the circuit for two large scintillation counters.

Extending a multichannel analyzer for two parameter pulse height analysis

The system described extends the utility of a 400 or 512 channel analyzer from a single parameter to a two parameter pulse height analyzer. This is done with a two parameter selector which selects the coincident events to be measured and also the memory subgroup to store them. It basically consists of a fast-slow coincidence circuit, an analog to digital converter (ADC), and four digital windows. Energies of events coincident in X and Y detectors are measured by the multichannel analyzer and ADC respectively. Four energy regions of the Y spectrum may be selected with the digital windows which sort out the X signals into the separate quadrants of the multichannel analyzer memory. Thus, the multichannel analyzer stores four X spectra each of which is in coincidence with a selected energy band in Y spectrum. Furthermore, a “live” intensity-modulated “map” of E y vs. E x (100 × 100 channels) can be displayed on an external oscilloscope. The combination of X- Y display and digital windows provides an efficient tool for making accurate, high resolution, two parameter analysis with a limited number of channels. In the non-coincidence mode the analyzer stores uncorrelated events from two detectors on a time sharing basis. The digital windows route these events to the two respective memory subgroups, as well as prevent spectral distortion due to chance coincidence.

Nanosecond multiple coincidence and anticoincidence circuit on tunnel diodes and transistors

A multi-coincidence and anticoincidence circuit made on tunnel diodes, diodes and transistors is described. The resolving time of the circuit measured with a meson beam is about 2 ns. The anticoincidence efficiency is as large as 0.9997.

Untersuchung des Vanadium-52-Zerfalls

Theγ-rays of the decay of V52 were investigated with NaJ crystals andγ-γ-cascades had been sought for by a fast-slow coincidence circuit. Threeγ-transitions of energyγ1=0,935 (0,14%),γ2=1,331 (0,9%),γ3=1,531 MeV (0,16%), respectively, in coincidence with the 1,434 MeV transition could be detected. It is concluded that there are four branches of V52β-decay:β0=2,47MeV (98,8%, logft=5,1),β1=1,53 MeV (0,14%, logft=7,0),β2=1,14 MeV (0,9%, logft=5,7),β3=0,94 MeV (0,16%, logft=6,1). Spin and parity of V52 ground level is concluded to be 3+.

Rechnungen zu den zeitlichen schwankungen von szintillationszähler-impulsen

The relation between the energy resolution and time resolution of a scintillation counter is discussed. Formulae for the approximate calculation of the resolving time are derived. Especially, coincidence circuits with double pulseshaping and those with variable threshold are considered. In both cases the influence of the fluctuations of the electron transit-time and of the amplifier cutoff frequency are essentially small and therefore neglected in the calculations. In a way this work is an extension on the work of E. Gatti and collaborators 1).

Measurement of half-lives of the 570 keV level of207Pb and 2083 keV and 2412 keV levels of140Ce

Delayed γ-γ and β-γ coincidence technique has been employed to measure the half-lives of the 570 keV level of207Pb and 2083 keV and 2412 keV levels of140Ce nuclei, which are found to be (1.8−0.5+0.2)·10−10 s, (3.3±0.4)·10−9 s and (7±3)·10−11 s, respectively. A bridge type coincidence circuit has been used as time-to-amplitude converter for these measurements. Its performance is described.

Oszillographische messung sehr kurzer auflösungszeiten

This paper presents a digital method of measuring the resolving time of coincidence circuits. To get a variable time distance between the testpulses, the feedbacks loops of two ring oscillators are made of slightly different lengths. From these oscillators the pulses are given separately on the coincidence being under test. At the output of that coincidence groups of pulses appear with a beat frequency. The envelopping shape of that group is the resolution function, which can directly be observed on the oscilloscope. With this method it is possible to follow the resolution curve in steps of less than 5 × 10−11 seconds.