Concept

Per cent mille

A per cent mille or pcm is one one-thousandth of a percent. It can be thought of as a "milli-percent". It is commonly used in epidemiology, and in nuclear reactor engineering as a unit of reactivity. Statistics of crime rates, mortality and disease prevalence in a population are often given in "per 100 000". In nuclear reactor engineering, a per cent mille is equal to one-thousandth of a percent of the reactivity, denoted by Greek lowercase letter rho. Reactivity is a dimensionless unit representing a departure from criticality, calculated by: where keff denotes the effective multiplication factor for the reaction. Therefore, one pcm is equal to: This unit is commonly used in the operation of light-water reactor sites because reactivity values tend to be small, so measuring in pcm allows reactivity to be expressed using whole numbers.

Official source

https://en.wikipedia.org/wiki/Per_cent_mille

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Related publications (2)

Identification of nano-phases: relative merit of local analysis techniques (HRTEM, nanodiffraction, EDS/EELS)

Philippe Buffat

Information for phase identification may be gathered in the electron transmission microscope with spatial resolution down to the nanometre scale. Energy dispersive X-ray and electron energy loss spectrometries are based on inelastic electron/sample interaction. They have the advantage to give a direct knowledge of the chemical nature of the atoms under the electron probe, sometimes also with valence and bonding, but concentrations are mean values over all atoms in the excited volume that may be insufficient

2004

Identification of nano-phases: relative merit of local analysis techniques (HRTEM, nanodiffraction, EDS/EELS)

Philippe Buffat

Information for phase identification may be gathered in the electron transmission microscope with spatial resolution down to the nanometre scale. Energy dispersive X-ray and electron energy loss spectrometries are based on inelastic electronsample interaction. They have the advantage to give a direct knowledge of the chemical nature of the atoms under the electron probe, sometimes also with valence and bonding, but concentrations are mean values over all atoms in the volume excited that may be insufficient

European Microscopy Society2004

Related people (1)

Philippe Buffat

Born in Lausanne (Switzerland) in 1942. EPUL physics engineer diploma in 1967 and EPFL PhD in physics in 1976. From 1966 he studies at the Experimental Physics Laboratory (Prof. J.P. Borel) the physical properties peculiar to the very small size metal crystals and gets a PhD degree for his thesis "Abaissement de la température de fusion de petits cristaux d'or par effet de taille thermodynamique" (Lowering of the melting temperature of small gold crystals by thermodynamic size effect). In 1971, he starts to develop an electron microscopy facility available to all EPFL students and researchers (nowadays Centre Interdisciplinaire de Microscopie Electronique CIME) that he manages till 2007. In parallel he teaches the principles of electron microscopy and the Experimental methods of physics at the Physics/Basic Sciences School (SB). In addition, he trains a large part of the facility users. Honorary professor BS/EPFL he carries-out a free-lance research at CIME and in collaboration with the Institute of Crystallography of the Russian Academy of Sciences (ICRAS, Moscow) and the International Centre of Electron Microscopy for Material Science (IC-EM AGH Krakow) This activity covers all the techniques related to transmission and scanning electron microscopy applied to materials science and solid-state physics. His interest is directed towards the structure of nanocrystals, their size effects and behavior under strong electron irradiation, the phase transitions in perovskites, the characterization of nanophases, multilayer and interface structures of crystalline materials and bioceramics. More recently a large research part has moved to understanding/pointing-out the adequacy between the limits of the instruments and their interpretation means in regard of their use in a multiusers facility with a large turnover and a wide range of materials/structures. He is past-president (2006-2007) of the Société Française des Microscopies (Sfµ), honorary member of the Sfµ and of the Swiss Society of Optics and Microscopy (SSOM).

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Official source

https://en.wikipedia.org/wiki/Per_cent_mille

About this result

Related publications (2)

Identification of nano-phases: relative merit of local analysis techniques (HRTEM, nanodiffraction, EDS/EELS)

Philippe Buffat

2004

Identification of nano-phases: relative merit of local analysis techniques (HRTEM, nanodiffraction, EDS/EELS)

Philippe Buffat

Information for phase identification may be gathered in the electron transmission microscope with spatial resolution down to the nanometre scale. Energy dispersive X-ray and electron energy loss spectrometries are based on inelastic electronsample interaction. They have the advantage to give a direct knowledge of the chemical nature of the atoms under the electron probe, sometimes also with valence and bonding, but concentrations are mean values over all atoms in the volume excited that may be insufficient

European Microscopy Society2004

Related people (1)

Philippe Buffat

Related concepts (3)

Percentage point

A percentage point or percent point is the unit for the arithmetic difference between two percentages. For example, moving up from 40 percent to 44 percent is an increase of 4 percentage points (although it is a 10-percent increase in the quantity being measured, if the total amount remains the same). In written text, the unit (the percentage point) is usually either written out, or abbreviated as pp or p.p. to avoid confusion with percentage increase or decrease in the actual quantity.

Per mille

Per mille () is parts per thousand. Other recognised spellings include per mil, per mill, permil, permill, or permille. The associated sign is written , which looks like a per cent sign with an extra zero or o in the divisor. Major dictionaries do not agree on the spelling and some dictionaries, such as Macmillan, do not even contain an entry. One common usage is blood alcohol content, which is usually expressed as a percentage in English-speaking countries. Per mille should not be confused with parts per million (ppm).

Percentage

In mathematics, a percentage () is a number or ratio expressed as a fraction of 100. It is often denoted using the percent sign (%), although the abbreviations pct., pct, and sometimes pc are also used. A percentage is a dimensionless number (pure number), primarily used for expressing proportions, but percent is nonetheless a unit of measurement in its orthography and usage. For example, 45% (read as "forty-five per cent") is equal to the fraction 45/100, the ratio 45:55 (or 45:100 when comparing to the total rather than the other portion), or 0.