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Topic: Prompt neutron

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	Neutron
		Three time intervals are involved: (a) the time it takes a fast neutron to slow down to thermal energy, (b) the time the now thermal neutron exists prior to absorption in fuel, and (c) the time required for a fissionable nucleus to emit a fast neutron after neutron absorption.
		Again, three time intervals are involved: (a) the time it takes a fast neutron to slow down to thermal energy, (b) the time the thermal neutron exists prior to absorption, and (c) the average time from neutron absorption to neutron emission by the six precursor groups.
		A prompt neutron generation time is the sum of the amount of time it takes a fast neutron to thermalize, the amount of time the neutron exists as a thermal neutron before it is absorbed, and the amount of time between a fissionable nuclide absorbing a neutron and fission neutrons being released.
	www.tpub.com /doenuclearphys/nuclearphysics48.htm (798 words)

	SDV Nuclear Glossary (Site not responding. Last check: 2007-10-14)
		Delayed neutrons account for approximately 0.75% of the neutron output from fission and this is an important aspect of controlling the increase in energy output of reactors.
		Absorption of a neutron by an atomic nucleus.
		Neutrons in one generation that are successfully moderated and that induce further fission reactions produce a new generation of neutrons.
	glossary.dataenabled.com /sdvglossary_neutrons.html (874 words)

	Large sample Prompt-Gamma Neutron Activation Analysis (Site not responding. Last check: 2007-10-14)
		Neutron activation analysis can now be applied to samples of kilogram scale without a priori knowledge of the sample’s composition.
		One of these neutron beams will be available for prompt gamma NAA which will have an end-point location at 25-30 m distance from the reactorcore.
		In the large sample PGNAA project, correction methods are being developed for neutron and gamma-ray self attenuation and a design is being made for the facility itself.
	www.iri.tudelft.nl /~rc/fmr/pgnaa_abs.html (459 words)

	Budapest Neutron Centre - PGAA - Prompt Gamma Activation Analysis Station (Site not responding. Last check: 2007-10-14)
		The prompt gamma activation analysis (PGAA) facility serves for non-destructive analysis of elemental composition by observing neutron-capture prompt gamma rays.
		When a nucleus captures a neutron, the binding energy of the neutron is emitted promptly in the form of gamma radiation.
		The neutron beam intensity of this facility is average, but its low background conditions are unique in the world.
	www.bnc.hu /modules.php?name=News&file=article&sid=4 (1682 words)

	Food & Nutrition Information
		Its detection specifies the neutrons in a given solid angle and, by appropriately gating the gamma detector, the resulting gamma ray spectrum is derived predominantly from neutron reactions within the defined volume of the sample.
		The detector was shielded from direct neutrons by housing it in a 5 cm thick lead cave with an outer, 15 cm thick, layer of wax and borated polystyrene.
		Prompt gamma rays of interest from the fast neutron reactions: C; 4.43 MeV, N; 7.03, 5.1, 5.03 and 4.46 MeV and O; 7.12, 6.92, 6.13 and 4.43 MeV.
	www.healthyeatingclub.com /APJCN/Volume4/vol4.1/mitral.htm (1808 words)

	Nuclear Engineering Teaching Laboratory - Prompt Gamma Activation Analysis
		Neutron capture prompt gamma activation analysis (PGAA) is a rapid, nondestructive, instrumental, nuclear technique which is used for trace and major component analysis of various elements.
		In association with the Neutron Activation Analysis (NAA), we have the capability of measuring the concentration of almost all elements.
		Nearly every neutron capture yields gamma rays that are potentially usable for analysis of the capturing element.
	www.me.utexas.edu /~netl/PromptGammaActivationAnalysis.htm (431 words)

	Axel Mohr: Diploma Thesis (Site not responding. Last check: 2007-10-14)
		High-resolution neutron diffraction has in the last years become an important engineering tool to make absolute and accurate measurements of three-dimensional residual stress fields non-destructively within metallic, ceramic and composite co,ponents.The high penetration of neutrons allows the measurement of lattice plane distances by coherent Bragg scattering Within the grains of polycrystalline engineering materials.
		Neutron TOF spectrometry has certain advantages in so far, as the relevant information about many different crystal planes comes from a fixed scattering volume and therefore a definition of the three-dimensional strain tensor.
		Prompt neutron capture can also be used to determine the presence of hydrogen within welds [2].
	www.geomar.de /~amohr/home_dir/dipl.html (1395 words)

	NCNR thermal neutron prompt gamma facility
		A new thermal neutron P G A A instrument became operational in 2001, replacing the original thermal neutron P G A A instrument that was built in the late 1970's.
		This was achieved by filtering the neutron beam to decrease the fast neutron and low energy gamma-ray components of the beam, designing the new facility components and support structure to minimize neutron capture gamma-rays, and installing an improved detection system.
		With the reduction in fast neutrons, the amount of hydrogenous shielding required to slow and capture the fast neutrons was reduced as compared with that needed in the old facility.
	www.ncnr.nist.gov /AnnualReport/FY2002_html/pages/thermal.htm (1044 words)

	prompt neutron -- Encyclopædia Britannica
		When the protons and neutrons in a nucleus of an atom are in a suitable ratio to each other, the nucleus shows no tendency to change, and the atom retains its chemical character.
		Composed of tightly packed neutrons, this type of star has a density many times greater than that of the sun but a diameter of only about 12 to 30 miles.
		A neutron star can be thought of as a gigantic atomic nucleus held together by its own gravity.
	www.britannica.com /eb/article?tocId=9061538 (924 words)

	REACTOR PERIODS AND REACTIVITY (Site not responding. Last check: 2007-10-14)
		Fundamentally, the neutron lifetime may be divided into two parts: (a) slowing down time, which is the mean time required for fission neutrons to slow to thermal energies and, (b) diffusion time, which is the average time that thermal neutrons will diffuse before absorption.
		Delayed neutrons are a small fraction of all neutrons in the reactor core.
		As positive reactivity is added to the critical reactor, the effects, in terms of time response and generation time, for prompt neutrons is enhanced and the effects for delayed neutrons are diminished.
	nucleus.wpi.edu /Reactor/Labs/L-rho.html (627 words)

	Prompt and Delayed Neutrons Summary
		Prompt neutrons are released directly from fission within 10 seconds of the
		neutron to the emission of the delayed neutron in the next generation.
		absorbing a neutron and fission neutrons being released.
	www.tpub.com /content/doe/h1019v1/css/h1019v1_136.htm (272 words)

	Prompt neutrons in fission (from nuclear fission) -- Encyclopædia Britannica
		The phenomenology of fission > Prompt neutrons in fission
		More results on "Prompt neutrons in fission (from nuclear fission)" when you join.
		The fission fragments are highly unstable because of their abnormally large number of neutrons compared with protons; consequently they...
	www.britannica.com /eb/article?tocId=48312 (936 words)

	Neutron Physics Division
		The general purpose of this project is the study, by means of neutron diffraction techniques, of the structure of the Omega phase in quenched Zr-Nb alloys, and the Omega - Beta mixtures in metastable equilibrium which are present in thermally treated alloys.
		Neutron moderation in media heterogeneously poisoned with a suitable neutron absorber is studied through extensive experimental research, and by means of numerical simulation.
		To obtain structural information from Neutron Scattering data of liquid and amorphous systems, it is imperative the evaluation of corrections due to multiple scattering and inelasticity, in order to extract the elastic coherent component in the observed spectra.
	www.cab.cnea.gov.ar /cab/ingNuclear/neutrones.html (1145 words)

	RP Mod 4 Section 1 Page 1
		There are several types of neutron sources in a reactor in operation.
		Prompt neutron production figures for 1000 fissions run as shown in Table-1.
		In reactor physics, we are interested in the average number of neutrons produced per fission.
	www.iaea.org /ns/nusafe/tutors/reactorphysics/module4/learningmaterial/section1p1.htm (117 words)

	[P] TERMS & DEFINITIONS IN NUCLEAR CHEMISTRY
		PHOTONEUTRON A neutron which is ejected from a nucleus as a consequence of the absorption of a photon.
		PROMPT GAMMA A gamma ray which is emitted from an excited state of a nucleus immediately upon formation of that excited state by a previous decay step or reaction.
		PULSED NEUTRONS Neutrons of transient high flux density produced in certain reactors when control rods are removed.
	www.radiochemistry.org /nomenclature/p.htm (1616 words)

	[No title] (Site not responding. Last check: 2007-10-14)
		We are installing neutron focusing devices to a thermal neutron beam line at JRR-3 (Japan Research Reactor No.3) for neutron beta decay measurement and neutron capture prompt gamma-ray analysis.
		A neutron beam is focused at a small sample for the trace element analysis by the prompt gamma-ray analysis.
		The neutron beam increased in flux by the focusing devices is also used for the neutron beta decay measurement to measure the electron-neutrino angular-correlation coefficient (little a-parameter) and verify the unitarity of CKM matrix.
	www.ill.fr /Events/SEMINAR/COLIII03Mar2005.html (221 words)

	Nat' Academies Press, Status of the Dosimetry for the Radiation Effects Research Foundation (DS86) (2001)
		The revised delayed neutron contribution to activation should be considered in comparing calculated and measured thermal activation.
		The DS86-calculated thermal and epithermal neutron fluences vary by as much as about 25–50% as the altitude increases from 1 m to 25 m (see Chapter 3).
		Kaul and Egbert (1989) estimate a CV of about 15% for both Hiroshima and Nagasaki for the uncertainty in the neutron kerma due to uncertainty in the new cross sections (see Chapter 4).
	www.nap.edu /books/0309075599/html/82.html (753 words)

	1984 Annual Symposium Paper D (Site not responding. Last check: 2007-10-14)
		From the laboratory trials, the best calibration accuracies (1 s) were 3% and 4% Mn for the activation analysis and prompt neutron-gamma techniques respectively with samples varying in grade from 7% to 50% Mn.
		The calibration accuracies obtained in similarly mineralized media at the mine, in dry shallow (15 m deep) boreholes of 150 mm diameter, were also about 4% Mn for the prompt neutron-gamma method, both for the entire mine and for the individual deposits at the mine.
		For logging based on neutron activation analysis, the calibration accuracy was less than 3.5% Mn in one area of the mine.
	www.spwla.org /library_info/abstract/sympo/1980/1984PaperD.html (233 words)

	[No title] (Site not responding. Last check: 2007-10-14)
		Directly (prompt) after absorption of the neutrons photons are emitted.
		These are (i) the absorption of neutrons, (ii) the scattering of neutrons and (iii) the absorption of photons.
		For each position in the sample the specified effects are studied separately with Monte Carlo simulations.Finally the correction methods are combined in a method for LS PGNAA.
	www.library.tudelft.nl /dissertations/2940/f_161812_true_EN.html (178 words)

	RP Mod 4 Section 2 Page 1
		When fission ceases, the emission of prompt neutrons also automatically ceases, but (some) fission fragments continue to emit neutrons via radioactive decay.
		The neutron emitted is a prompt neutron, but it occurs some time after the original fission, since the Br must decay first.
		Table-2 displays the characteristics of the delayed neutrons in thermal fission.
	www.iaea.org /ns/nusafe/tutors/reactorphysics/module4/learningmaterial/section2p1.htm (128 words)

	Department of Nuclear Engineering: Reports to the President 2001-2002
		Neutron capture therapy for cancer research, directed by Professor Otto K. Harling, continued for the 15th year with strong support from federal agencies.
		This beam is a high intensity thermal neutron beam to be used for small animal irradiations and clinical studies of skin cancer therapy.
		Fast neutron radiography is a potential method for non-destructive examination of large dense structures; which are not accessible to other techniques.
	web.mit.edu /annualreports/pres02/08.07.html (6279 words)

	ExploStudy, Final Report, 17/2/2001
		Thermal neutrons are a special type of slow neutrons, whose kinetic energy distribution is in equilibrium with their surrounding (with a typical energy of 0.025 eV at room temperature).
		Concerning possible thermal neutron sources, the D-T generator is far from optimal for (pure) TNA as the 14 MeV neutrons are difficult to shield and produce quite some background.
		The fast neutrons thus produced are therefore also defined as "tagged" (by the associated particle), in time as well as in direction, which can lead to a significant reduction in background signal.
	diwww.epfl.ch /lami/detec/explostudy.html (11227 words)

	[No title] (Site not responding. Last check: 2007-10-14)
		A neutron of weight 1 and energy 5 Mev has several elastic events followed by an n,g event (Q for n,g is 6.1 Mev), all in the detector - a count of 1 in the energy bin containing 11.1 (5 + Q) Mev.
		A neutron of weight 1 and energy 5 Mev has several elastic events followed by an n,g event (Q for n,g is 6.1 Mev), all in the detector, the photons escape without losing any energy in the detector - a count of 1 in the energy bin containing 5 Mev.
		If a neutron's energy exceeds the database high energy limit, then the corresponding XS values (integrated cross section, energy distribution, etc.) are taken to be those at the high energy limit.
	www-phys.llnl.gov /N_Div/COG/COGUsersNotes.txt (11361 words)

	Instinct Training Ltd. - Nuclear Plant Theory - Neutron Kinetics
		The purpose of this title is to give a qualitative understanding of reactor behaviour using simplified assumptions on neutron kinetics.
		Sketch the graphs of neutron flux against time for a subcritical, critical and supercritical reactor.
		Understand the term Prompt Neutron Lifetime and its application to a graphite moderated reactor.
	www.instinct-training.co.uk /nuclear/na.htm (194 words)

	KFKI AEKI (Site not responding. Last check: 2007-10-14)
		Three research institutes of the Hungarian Academy of Sciences set up the Budapest Neutron Centre (BNC) for the utilisation of the reactor in the field of basic research.
		The cold neutron source (CNS) has been working continually throughout the year-- although initially it was not running optimally.
		In 2000, BNC organised a workshop on applications of neutron scattering in chemistry, archaeology and biology.
	www.kfki.hu /~aekihp/reports2001/bnc.htm (281 words)

	Nukes Nuclear bombs Missile Defense ICBMs (Site not responding. Last check: 2007-10-14)
		A thermonuclear device designed to yield up to 80% of its energy in the form of high-energy neutrons (ordinary nuclear weapons produce most of their energy as blast and heat).
		Prompt or immediate radiation is enhanced by reducing the fission yield relative to the fusion yield (ie.
		This fusion reaction releases up to six times as many neutrons as an equivalent pure fission or fission-fusion-fission device, and these have an energy level of some 14 billion electron volts.
	www.danshistory.com /nuke.shtml (5640 words)

	[No title] (Site not responding. Last check: 2007-10-14)
		J.K. Shultis and D.S. McGregor, "Efficiencies of Coated and Perforated Semiconductor Neutron Detectors," submitted to IEEE Trans.
		D.S. McGregor and J.K. Shultis, "Spectral Identification of Thin-Film-Coated and Solid-Form Semiconductor Neutron Detectors," Nuclear Instruments and Methods, A517, 180--188, 2004.
		R.E. Faw and J.K. Shultis "Photon and Neutron Dose Conversion Functions," Ch.
	ww2.mne.ksu.edu /~jks/resume.htm (1414 words)

	[No title]
		An element is identified by the number of protons in its nucleus, while varying numbers of neutrons indicate different atomic isotopes (nuclides) of the same element (review delayed gamma theory).
		As in delayed gamma activation, incoming neutrons combine with an atom, in this case nitrogen, to form a nuclide of the same element.
		Once the neutron source is removed, the gamma signal from the nitrogen ceases.
	www.bcm.edu /bodycomplab/pgtheorypage.htm (147 words)

	ARS \| Publication request: Estimation of Background Interference in Prompt-Gamma Neutron Activation Using Mcnp
		Interpretive Summary: Prompt-gamma neutron activation (PGNA) is a method of measuring the total amount of nitrogen in a person's body, which is converted into protein, giving an idea of the proportion of lean tissue as a health-related yardstick.
		Technical Abstract: Prompt-gamma neutron activation (PGNA) is used to measure total-body nitrogen (TBN) and hydrogen (TBH) in humans.
		The magnitude of this interference is difficult to ascertain directly, since the absence of a subject on the scanner alters the conditions for neutron scattering and thermalization.
	www.ars.usda.gov /research/publications/publications.htm?SEQ_NO_115=111869 (464 words)

	Abstract: DEVELOPMENT OF ADVANCED NEUTRON INDUCED PROMPT GAMMA-RAY ANALYSIS SYSTEM FOR SURVEY OF ANTI-PERSONNEL MINES (Site not responding. Last check: 2007-10-14)
		Since explosives used in APM are rich in nitrogen(N) content, neutron capture reaction of N, resulting in the emission of 10.8 MeV ?-rays, is used for its detection.
		The neutron source developed is a Cockcroft Walton type accelerator, of which size is 180mm in diameter and 450mm in length, utilizing deuterium-deuterium reactions producing 2.8 MeV neutrons at maximum.
		By adopting an RF heating helical plasma ion, the neutron intensity would be reached up to 3×108 n/s in time average.
	www.ndt.net /abstract/wcndt2004/664.htm (212 words)

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