Shift-register Coincidence Electronics System for Thermal Neutron Counters

Shift-register Coincidence Electronics System for Thermal Neutron Counters
Author:
Publisher:
Total Pages:
Release: 1980
Genre:
ISBN:

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An improved shift-register, coincidence-counting logic circuit, developed for use with thermal neutron well counters, is described in detail. A distinguishing feature of the circuit is its ability to operate usefully at neutron counting rates of several hundred kHz. A portable electronics package incorporating the new coincidence logic and support circuits is also described.

Handbook of Radioactivity Analysis

Handbook of Radioactivity Analysis
Author: Michael F. L'Annunziata
Publisher: Academic Press
Total Pages: 1420
Release: 2012-08-16
Genre: Medical
ISBN: 0123848733

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Authoritative reference providing the principles, practical techniques, and procedures for the accurate measurement of radioactivity.

International Plutonium Control Act--H.R. 2403

International Plutonium Control Act--H.R. 2403
Author: United States. Congress. House. Committee on Foreign Affairs
Publisher:
Total Pages: 344
Release: 1990
Genre: National security
ISBN:

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Energy Research Abstracts

Energy Research Abstracts
Author:
Publisher:
Total Pages: 806
Release: 1992
Genre: Power resources
ISBN:

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Optimal Gate-width Setting for Passive Neutrons Multiplicity Counting

Optimal Gate-width Setting for Passive Neutrons Multiplicity Counting
Author:
Publisher:
Total Pages:
Release: 2010
Genre:
ISBN:

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When setting up a passive neutron coincidence counter it is natural to ask what coincidence gate settings should be used to optimize the counting precision. If the gate width is too short then signal is lost and the precision is compromised because in a given period only a few coincidence events will be observed. On the other hand if the gate is too large the signal will be maximized but it will also be compromised by the high level of random pile-up or Accidental coincidence events which must be subtracted. In the case of shift register electronics connected to an assay chamber with an exponential dieaway profile operating in the regime where the Accidentals rate dominates the Reals coincidence rate but where dead-time is not a concern, simple arguments allow one to show that the relative precision on the net Reals rate is minimized when the coincidence gate is set to about 1.2 times the lie dieaway time of the system. In this work we show that making the same assumptions it is easy to show that the relative precision on the Triples rates is also at a minimum when the relative precision of the Doubles (or Reals) is at a minimum. Although the analysis is straightforward to our knowledge such a discussion has not been documented in the literature before. Actual measurement systems do not always behave in the ideal we choose to model them. Fortunately however the variation in the relative precision as a function of gate width is rather flat for traditional safeguards counters and so the performance is somewhat forgiving of the exact choice. The derivation further serves to delineate the important parameters which determine the relative counting precision of the Doubles and Triples rates under the regime considered. To illustrate the similarities and differences we consider the relative standard deviation that might be anticipated for a passive correlation count of an axial section of a spent nuclear fuel assembly under practically achievable conditions.

INIS Atomindeks

INIS Atomindeks
Author:
Publisher:
Total Pages: 1360
Release: 1987
Genre: Nuclear energy
ISBN:

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Portable Shift Register

Portable Shift Register
Author:
Publisher:
Total Pages: 8
Release: 1994
Genre:
ISBN:

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An electronics package for a small, battery-operated, self-contained, neutron coincidence counter based on a portable shift-register (PSR) has been developed. The counter was developed for applications not adequately addressed by commercial packages, including in-plant measurements to demonstrate compliance with regulations (domestic and international), in-plant process control, and in-field measurements (environmental monitoring or safeguards). Our package's features, which address these applications, include the following: Small size for portability and ease of installation;battery or mains operation; a built-in battery to power the unit and a typical detector such as a small sample counter, for over 6 h if power lines are bad or noisy, if there is a temporary absence of power, or if portability is desired; complete support, including bias, for standard neutron detectors; a powerful communications package to easily facilitate robust external control over a serial port; and a C-library to simplify creating external control programs in computers or other controllers. Whereas the PSR specifically addresses the applications mentioned above, it also performs all the measurements made by previous electronics packages for neutron coincidence counters developed at Los Alamos and commercialized. The PSR electronics package, exclusive of carrying handle, is 8 by 10 by 20 cm; it contains the circuit boards, battery, and bias supply and weighs less than 2 kg. This instrument package is the second in an emerging family of portable measurement instruments being developed; the first was the Miniature and Modular Multichannel Analyzer (M[sup 3]CA). The PSR makes extensive use of hardware and software developed for the M[sup 3]CA; like the M[sup 3]CA, it is intended primarily for use with an external controller interfaced over a serial channel.

The Effect of Deadtime and Electronic Transients on the Predelay Bias in Neutron Coincidence Counting

The Effect of Deadtime and Electronic Transients on the Predelay Bias in Neutron Coincidence Counting
Author:
Publisher:
Total Pages: 8
Release: 2016
Genre:
ISBN:

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In neutron coincidence counting using the shift register autocorrelation technique, a predelay is inserted before the opening of the (R+A)-gate. Operationally the purpose of the predelay is to ensure that the (R+A)- and A-gates have matched effectiveness, otherwise a bias will result when the difference between the gates is used to calculate the accidentals corrected net reals coincidence rate. The necessity for the predelay was established experimentally in the early practical development and deployment of the coincidence counting method. The choice of predelay for a given detection system is usually made experimentally, but even today long standing traditional values (e.g., 4.5 μs) are often used. This, at least in part, reflects the fact that a deep understanding of why a finite predelay setting is needed and how to control the underlying influences has not been fully worked out. We attempt, in this paper, to gain some insight into the problem. One aspect we consider is the slowing down, thermalization, and diffusion of neutrons in the detector moderator. The other is the influence of deadtime and electronic transients. These may be classified as non-ideal detector behaviors because they are not included in the conventional model used to interpret measurement data. From improved understanding of the effect of deadtime and electronic transients on the predelay bias in neutron coincidence counting, the performance of both future and current coincidence counters may be improved.