A Daly detector is a gas-phase ion detector that consists of a metal "doorknob", a

scintillator A scintillator is a material that exhibits scintillation, the property of luminescence, when excited by ionizing radiation. Luminescent materials, when struck by an incoming particle, absorb its energy and scintillate (i.e. re-emit the absorbe ...

(

phosphor A phosphor is a substance that exhibits the phenomenon of luminescence; it emits light when exposed to some type of radiant energy. The term is used both for fluorescent or phosphorescent substances which glow on exposure to ultraviolet or v ...

screen) and a

photomultiplier A photomultiplier is a device that converts incident photons into an electrical signal. Kinds of photomultiplier include: * Photomultiplier tube, a vacuum tube converting incident photons into an electric signal. Photomultiplier tubes (PMTs for sh ...

.N. R. Daly
Scintillation Type Mass Spectrometer ion Detector
. ''Rev. Sci. Instrum.'' 31(3), 264–267 (1960). It was named after its inventor Norman Richard Daly. Daly detectors are typically used in

mass spectrometer Mass spectrometry (MS) is an analytical technique that is used to measure the mass-to-charge ratio of ions. The results are presented as a '' mass spectrum'', a plot of intensity as a function of the mass-to-charge ratio. Mass spectrometry is us ...

Principle of operation

Ions that hit the doorknob release secondary electrons. A high voltage (about ) between the doorknob and the scintillator accelerates the electrons onto the phosphor screen, where they are converted to photons. These photons are detected by the

. The advantage of the Daly detector is that the photomultiplier can be separated by a window, which lets the photons through from the high vacuum of the mass spectrometer, thus preventing an otherwise possible contamination and extending life span of the detector. The Daly detector also allows a higher acceleration after the field-free region of a

time-of-flight mass spectrometer Time-of-flight mass spectrometry (TOFMS) is a method of mass spectrometry in which an ion's mass-to-charge ratio is determined by a time of flight measurement. Ions are accelerated by an electric field of known strength. This acceleration resu ...

flight tube, which can improve the sensitivity for heavy ions.

Norman Richard Daly

Norman Daly was awarded 6 patents in the years 1962–1973 relating to ion detection and mass spectrometers, from his work at the

United Kingdom Atomic Energy Authority The United Kingdom Atomic Energy Authority is a UK government research organisation responsible for the development of fusion energy. It is an executive non-departmental public body of the Department for Business, Energy and Industrial Strategy ...

References

{{Mass spectrometry Mass spectrometry Measuring instruments Photochemistry Particle detectors Phosphors and scintillators