Akademik

A device that counts, usually scintillations.

- automated differential leukocyte c. an instrument using digital imaging or cytochemical techniques to differentiate leukocytes.

- electronic cell c. an automatic blood cell c. in which cells passing through an aperture alter resistance and are counted as voltage pulses, or in which cells passing through a flow cell deflect light; some types of c. are capable of multiple simultaneous measurements on each blood sample; e.g., leukocyte count, red cell count, hemoglobin, hematocrit, and red cell indices.

- Geiger-Müller c. an instrument for measuring radioactivity by counting the emission of radioactive particles; it consists of a metallic cylinder, negatively charged, in a tube containing a fine, positively charged wire at its center; radiations produce ionization of the gas molecules between the cylinder and the wire and result in an electrical discharge independent of the energy of the impinging particle or ray.

- proportional c. a Geiger-Müller c. operating in the voltage range and under conditions in which pulse height is proportional to the energy of the particles or rays being counted, thus making discrimination between particles or rays of different energies possible.

- scintillation c. an instrument used for the detection of radioactivity; the radiation is absorbed by a scintillator (a crystal or a compound, such as POPOP, in solution) which results in minute flashes of light that are detected by a photocathode. The resultant electron emission is amplified by a photomultiplier and an amplifier. SYN: scintillometer, spinthariscope.

- well c. a scintillation crystal shaped with a central hole to receive a small sample, plus associated detector and electronics.

- whole-body c. shielding and instrumentation, usually involving more than one detector, designed to evaluate the total-body burden of various gamma-emitting nuclides.

count·er 'kau̇nt-ər n a level surface over which transactions are conducted or food is served or on which goods are displayed or work is conducted <a lunch \counter> - over the counter without a prescription <drugs available over the counter>

counter n one that counts esp a device for indicating a number or amount see GEIGER COUNTER