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  2. Radiocarbon dating - Wikipedia

    en.wikipedia.org/wiki/Radiocarbon_dating

    C, which are used to calculate Fm, the "fraction modern". This is defined as the ratio between the 14 C / 12 C ratio in the sample and the 14 C / 12 C ratio in modern carbon, which is in turn defined as the 14 C / 12 C ratio that would have been measured in 1950 had there been no fossil fuel effect. [73]

  3. Radiocarbon calibration - Wikipedia

    en.wikipedia.org/wiki/Radiocarbon_calibration

    Radiocarbon dating measurements produce ages in "radiocarbon years", which must be converted to calendar ages by a process called calibration.Calibration is needed because the atmospheric 14

  4. Calculation of radiocarbon dates - Wikipedia

    en.wikipedia.org/wiki/Calculation_of_radiocarbon...

    Activity levels, after being normalized to δ 13 C of -25‰, can be divided by this in order to calculate the "radiocarbon age". But as part of their methodology both beta counting and AMS measure standard samples containing carbon of a known activity, and the activity of the sample is divided by the activity of the standard. [8]

  5. Bomb pulse - Wikipedia

    en.wikipedia.org/wiki/Bomb_pulse

    Given radioactive decay (14 C's half-life is about 5,730 years), the relative amount of 14 C left in the dead organism can be used to calculate how long ago it died. Bomb pulse dating should be considered a special form of carbon dating.

  6. Radiocarbon dating considerations - Wikipedia

    en.wikipedia.org/wiki/Radiocarbon_dating...

    A polarity excursion, which can be either global or local, is a shorter-lived version of a geomagnetic reversal. A local excursion would not significantly affect 14C production. During either a geomagnetic reversal or a global polarity excursion, 14 C production increases during the period when the geomagnetic field is weak. It is fairly ...

  7. Carbon-14 - Wikipedia

    en.wikipedia.org/wiki/Carbon-14

    Carbon-14, C-14, 14 C or radiocarbon, is a radioactive isotope of carbon with an atomic nucleus containing 6 protons and 8 neutrons.Its presence in organic matter is the basis of the radiocarbon dating method pioneered by Willard Libby and colleagues (1949) to date archaeological, geological and hydrogeological samples.

  8. HP calculators - Wikipedia

    en.wikipedia.org/wiki/HP_calculators

    Smaller programmable model with programs up to 49 steps. Version HP-25C was first calculator with "continuous memory". HP-27S: 1988 The first HP pocket calculator to use algebraic notation only rather than RPN. It was a "do all" calculator that included algebraic solver like the HP-18C, statistical, probability and time/value of money ...

  9. Curta - Wikipedia

    en.wikipedia.org/wiki/Curta

    A partially disassembled Curta calculator, showing the digit slides and the stepped drum behind them Curta Type I calculator, top view Curta Type I calculator, bottom view. The Curta is a hand-held mechanical calculator designed by Curt Herzstark. [1] It is known for its extremely compact design: a small cylinder that fits in the palm of the hand.