N  1. Neutron number . 2. In dosimetry, the factor designed to take into account all parameters influencing a dose equivalent , except the absorbed dose  and type and energy of the radiation . IUPAC82...

NAA  Neutron activation analysis .

NaI(Tl) DETECTOR  A scintillation crystal  made of thallium-activated sodium iodide and used as a scintillation detector .

NATURAL ISOTOPIC ABUNDANCE  See abundance, natural isotopic .

NATURAL RADIOACTIVITY  Radioactivity of naturally occurring nuclides  in materials where the isotopic abundance  of that nuclide  is natural . IUPAC82..

NCA  No carrier  added. J.

NDP  (1). Neutron diagnostic probe. (2). Neutron depth profiling.

NEGATRON  A negative beta-particle .

NEUTRINO  Any of several neutral, possibly massless particles always involved with electrons in beta-decay  nuclear transformations.

NEUTRON ACTIVATION  See activation .

NEUTRON CAPTURE  A nuclear reaction in which a neutron  is absorbed by a target nucleus producing an isotope one mass number greater in its ground or excited states.

NEUTRON DENSITY  The number of free neutrons divided by the containing volume. Partial densities may be defined for neutrons characterized by such parameters as energy and directions. IUPAC82..

NEUTRON DEPTH PROFILING  A method of charged particle activation analysis  in which deuterons of specific energy undergo (d,n) reactions in which the neutron energy spectrum is measured by time-of-flight  techniques. The energy is a measure of the deuteron's energy when the reaction occurred and therefore a probe of how deep the reacting element is in the sample. The intensity of detected neutrons is a measure of reacting element concentration. NAC.

NEUTRON DIAGNOSTIC PROBE  A device for prompt analysis that is a combination of a neutron generator , an alpha-particle counter for time-of-flight  neutron spectrometry, and a detector for inelastic gamma-ray spectroscopy.

NEUTRON EXCESS  The number of neutrons in excess of the number of protons in a nuclide .

NEUTRON FLUX  See flux density, particle .

NEUTRON GENERATOR  1.) An accelerator, usually small, of light charged ions (p, d, t) which produces a flux of neutrons through nuclear reactions in a light element target. 2.) Any device which produces neutrons.  

NEUTRON NUMBER  The number of neutrons  in a nucleus.

NEUTRONS, COLD  Neutrons  with a neutron temperature  considerably lower than normal room temperature. IUPAC82..

NEUTRONS, DELAYED  Neutrons  emitted by fission products formed by nuclear decay  (the observed delay is due to the lifetime of the preceding nuclear decay or decays.

NEUTRONS, EPICADMIUM  Neutrons  of kinetic energy greater than the effective cadmium cut-off  for neutrons.

NEUTRONS, EPITHERMAL  Neutrons  of kinetic energy greater than that of thermal agitation. The term is often restricted to energies just above thermal. IUPAC82..

NEUTRONS, FAST  Neutrons  of kinetic energy greater than some specified value. This value may vary over a wide range and will be dependent upon the application, such as reactor physics, shielding or dosimetry. IUPAC82..

NEUTRONS, FISSION  Neutrons  originating in the fission  process which have retained their original energy. IUPAC82..

NEUTRONS, INTERMEDIATE  Neutrons  of kinetic energy between the energies of slow  and fast neutrons . In reactor physics, the range might be 1 eV to 0.1 MeV. IUPAC82..

NEUTRONS, PROMPT  Neutrons  accompanying the fission  process without measurable delay. IUPAC82..

NEUTRONS, SLOW  Neutrons  of kinetic energy less than some specified value. This value may vary over a wide range and depends on the application.  In reactor physics, the value is frequently chosen to be 1 eV; in dosimetry , the effective cadmium cut-off  is used. IUPAC82..

NEUTRONS, THERMAL  Neutrons  in thermal equilibrium with the medium in which they exist. IUPAC82..

NEUTRON TEMPERATURE  The temperature assigned to a population of neutrons when this population is approximated by a Maxwellian distribution. C.

NICK TRANSLATION  Labeling procedure in which DNA is first "nicked" (broken) and a radioactive nucleotide is re-included by the action of DNA polymerase. J.  

NIM MODULE  An electronic component for nuclear instrumentation packaged in a standardized way to allow interchangability with alternative units and to provide compatibility with equivalently standardized housing and powering units (bins) called NIM bins .

NIMBIN  Standard bins for housing and supplying power to complementarily standardized electronics called nuclear instrument modules, or NIM modules .

NO CARRIER ADDED  A preparation of a radioactive isotope  which is essentially free from stable isotopes of the element in question. IUPAC94.

NONACTIVATION ANALYSIS  Methods of analysis based on the interaction of nuclear radiation or X-rays with the sample, leading to absorption and backscattering, not to activation  of the determined component. HRC.

NON-DESTRUCTIVE ACTIVATION ANALYSIS  See activation analysis.  

NON-IONIZING RADIATION  Radiation , the energy of which is insufficient to produce ions in matter. Included are microwaves, infrared light, visible light and slow neutrons. In most cases, ultraviolet radiation may be considered a non-ionizing radiation too.

NON-SPECIFIC BINDING  That portion of the tracer used in a competitive binding assay  that is found in the bound fraction, independent of the binding reaction. Also expressed as minimum binding. NM.

NRA  Nuclear reaction analysis.

NSB  See non-specific binding .

NUCLEAR ACTIVATION ANALYSIS  See activation analysis.

NUCLEAR CHEMISTRY  See chemistry, nuclear .

NUCLEAR DECAY  See decay, nuclear .

NUCLEAR EMULSION  A photographic emulsion specially prepared for the detection of nuclear particles. Such emulsions are generally thicker and contain a higher concentration of silver halide than those used for standard photography. The emulsion is usually deposited on a glass plate. NM.

NUCLEAR FISSION  See fission, nuclear .

NUCLEAR FORCE  See force, nuclear .

NUCLEAR FUSION  See fusion, nuclear .

NUCLEAR GEOLOGY  Application of nuclear science and techniques to geologic studies.

NUCLEAR ISOMERS  See isomers, nuclear .

NUCLEAR MEDICINE  A branch of medicine "taken to embrace all applications of radioactive materials in diagnosis or treatment or in medical research with the exception of the use of sealed radiation sources in radiotherapy". (World Health Organization, 1972); "the clinical and laboratory medical specialty that employs for diagnosis, therapy, and research the nuclear properties of radioactive and stable nuclides to evaluate metabolic, physiologic, and pathologic conditions of the body" (American Board of Nuclear Medicine); "devoted to the diagnosis, treatment, research, and prevention of disease by making use of unsealed radioactive sources and of the properties of stable radionuclides" (Council of Europe and the Society of Nuclear Medicine Europe). Direct therapy using accelerators is also included.

NUCLEAR MICROPROBE  A charged-particle  or ion beam  with excellent spatial resolution and used for nuclear reaction analysis . FR.

NUCLEAR MIGRATION  Transport of nuclides from their point of origin by natural processes.

NUCLEAR PARTICLE  See particle, nuclear .

NUCLEAR PHARMACEUTICALS  See radiopharmaceuticals .

NUCLEAR RADIUS  The geometrical radius of the atomic nucleus; because of the relative incompressibility of nuclear matter, it is approximately proportional to the cube root of the atomic number  of the nucleus.  

NUCLEAR REACTION  A transformation of a nucleus which occurs (i ) when another nuclear particle approaches closely enough to be influenced by the mutual attractive nuclear force between them or (ii) when affected by an electromagnetic force of sufficient strength.

NUCLEAR REACTION ANALYSIS  Charged-particle  induced nuclear reactions for determination of elements, usually depth profiling  of light elements. FR.

NUCLEAR REACTOR  See reactor, nuclear .

NUCLEAR RESONANCE BROADENING  A technique used for obtaining concentration depth profiles  by comparing resonant charged-particle capture gamma-ray yields from an unknown distribution in a sample to those yields from a known distribution of the same isotope. Frequently, the latter distribution is just the natural isotopic mixture.

NUCLEAR RESONANCE SCATTERING  Mössbauer effect .

NUCLEAR SOLID STATE TRACK DETECTOR  See solid state track detector .  

NUCLEAR SPECTROSCOPY  The measurement of the energy spectrum of particles emitted or scattered from nuclei.

NUCLEAR SPIN  See spin, nuclear .

NUCLEAR TRANSFORMATION  See transformation, nuclear .

NUCLEAR TRANSITION  See transition, nuclear .

NUCLEIDE  Nuclide  is preferred.

NUCLEON  A proton  or a neutron . IUPAC82..

NUCLEONICS  The practical applications of nuclear science and the techniques associated with these applications. NM.

NUCLEON NUMBER  Number of nucleons  in a nucleus . IUPAC82..

NUCLEOPORE FILTER  A filter with micron and submicron sized pores. The pores are of controlled and uniform size, produced by chemically etching radiation damage tracks of heavy ions with which the filters are bombarded as part of the production process.

NUCLEUS  The positively charged central portion of an atom , excluding the orbital electrons . IUPAC82..

NUCLIDE  A species of an atom  characterized by its mass number, atomic number  and nuclear energy state, provided that the mean life  in that state is long enough to be observable. IUPAC82..

NUCLIDIC MASS  The rest mass  of a nuclide  expressed in atomic mass units. IUPAC82..