Energy Research Abstracts

Energy Research Abstracts
Author:
Publisher:
Total Pages: 366
Release: 1993-02
Genre: Power resources
ISBN:

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The Feynman-Y Statistic in Relation to Shift-Register Neutron Coincidence Counting

The Feynman-Y Statistic in Relation to Shift-Register Neutron Coincidence Counting
Author:
Publisher:
Total Pages:
Release: 2012
Genre:
ISBN:

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The Feynman-Y statistic is a type of autocorrelation analysis. It is defined as the excess variance-to-mean ratio, Y = VMR - 1, of the number count distribution formed by sampling a pulse train using a series of non-overlapping gates. It is a measure of the degree of correlation present on the pulse train with Y = 0 for Poisson data. In the context of neutron coincidence counting we show that the same information can be obtained from the accidentals histogram acquired using the multiplicity shift-register method, which is currently the common autocorrelation technique applied in nuclear safeguards. In the case of multiplicity shift register analysis however, overlapping gates, either triggered by the incoming pulse stream or by a periodic clock, are used. The overlap introduces additional covariance but does not alter the expectation values. In this paper we discuss, for a particular data set, the relative merit of the Feynman and shift-register methods in terms of both precision and dead time correction. Traditionally the Feynman approach is applied with a relatively long gate width compared to the dieaway time. The main reason for this is so that the gate utilization factor can be taken as unity rather than being treated as a system parameter to be determined at characterization/calibration. But because the random trigger interval gate utilization factor is slow to saturate this procedure requires a gate width many times the effective 1/e dieaway time. In the traditional approach this limits the number of gates that can be fitted into a given assay duration. We empirically show that much shorter gates, similar in width to those used in traditional shift register analysis can be used. Because the way in which the correlated information present on the pulse train is extracted is different for the moments based method of Feynman and the various shift register based approaches, the dead time losses are manifested differently for these two approaches. The resulting estimates for the dead time corrected first and second order reduced factorial moments should be independent of the method however and this allows the respective dead time formalism to be checked. We discuss how to make dead time corrections in both the shift register and the Feynman approaches.

Government Reports Annual Index

Government Reports Annual Index
Author:
Publisher:
Total Pages: 1442
Release: 1994
Genre: Research
ISBN:

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Sections 1-2. Keyword Index.--Section 3. Personal author index.--Section 4. Corporate author index.-- Section 5. Contract/grant number index, NTIS order/report number index 1-E.--Section 6. NTIS order/report number index F-Z.

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.

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.

Strategy and Methodology for Radioactive Waste Characterization

Strategy and Methodology for Radioactive Waste Characterization
Author: International Atomic Energy Agency
Publisher: IAEA
Total Pages: 188
Release: 2007
Genre: Business & Economics
ISBN:

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Over the past decade significant progress has been achieved in the development of waste characterization and control procedures and equipment as a direct response to ever-increasing requirements for quality and reliability of information on waste characteristics. Failure in control procedures at any step can have important, adverse consequences and may result in producing waste packages which are not compliant with the waste acceptance criteria for disposal, thereby adversely impacting the repository. The information and guidance included in this publication corresponds to recent achievements and reflects the optimum approaches, thereby reducing the potential for error and enhancing the quality of the end product. -- Publisher's description.

The 2030 Spike

The 2030 Spike
Author: Colin Mason
Publisher: Routledge
Total Pages: 256
Release: 2013-06-17
Genre: Law
ISBN: 1136555110

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The clock is relentlessly ticking! Our world teeters on a knife-edge between a peaceful and prosperous future for all, and a dark winter of death and destruction that threatens to smother the light of civilization. Within 30 years, in the 2030 decade, six powerful 'drivers' will converge with unprecedented force in a statistical spike that could tear humanity apart and plunge the world into a new Dark Age. Depleted fuel supplies, massive population growth, poverty, global climate change, famine, growing water shortages and international lawlessness are on a crash course with potentially catastrophic consequences. In the face of both doomsaying and denial over the state of our world, Colin Mason cuts through the rhetoric and reams of conflicting data to muster the evidence to illustrate a broad picture of the world as it is, and our possible futures. Ultimately his message is clear; we must act decisively, collectively and immediately to alter the trajectory of humanity away from catastrophe. Offering over 100 priorities for immediate action, The 2030 Spike serves as a guidebook for humanity through the treacherous minefields and wastelands ahead to a bright, peaceful and prosperous future in which all humans have the opportunity to thrive and build a better civilization. This book is powerful and essential reading for all people concerned with the future of humanity and planet earth.

14 MeV Neutrons

14 MeV Neutrons
Author: Vladivoj Valkovic
Publisher: CRC Press
Total Pages: 500
Release: 2015-08-25
Genre: Science
ISBN: 1482238012

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Despite the often difficult and time-consuming effort of performing experiments with fast (14 MeV) neutrons, these neutrons can offer special insight into nucleus and other materials because of the absence of charge. 14 MeV Neutrons: Physics and Applications explores fast neutrons in basic science and applications to problems in medicine, the envir