In general terms, phosphor is a substance that exhibits the phenomenon of luminescence which includes phosphorescent and florescent. The former has a slow decay time of >1ms, whereas in the latter, emission decay happens over tens of nanoseconds.
Phosphors are designated by the letter P followed by a number. Phosphors are often rare-earth compounds with an activator. The activators in phosphor prolong the emission time (afterglow) or sometimes can be used to quench and shorten it’s afterglow.
The common parameters for phosphor are the wavelength of emission (in nanometers), the peak width (in nanometers @ 50% intensity) and decay time (in seconds).
A scintillator is a material that exhibits scintillation, the property of luminescence, when it’s excited by ionising radiation. Luminescent materials when struck by an incoming particle, absorb it’s energy and scintillate, by re-emitting the absorbed energy as visible photons.
A scintillator is often paired with an electronic light sensor such a photomultiplier tube (PMT), photodiode or a silicon photomultiplier to form a scintillator detector or scintillation counter.
PMTs absorb the light emitted by the scintillator and re-emit it in the form of electrons via the photoelectric effect. The multiplication of these photo-electrons results in an electrical pulse which is then analysed and yields information about the particle that struck the scintillator.
Analytical Components can design phosphor screens to match your specific needs, in line with your application.
Dielectric (Non-Conductive) substrates such as FOPs (Fibre Optic Plates), and Float glass can be coated with a conductive coating known as ITO (Indium Tin Oxide) to achieve an electrical connection between the screen and the instrument.
A layer of Aluminium can be added to our phosphor screens which can make the screen conductive and helps to focus all light towards the layer of phosphor, and its detector, thus decreasing the potential for stray photons. Usually, 3Kv accretion voltage is needed for electrons to pass through an Aluminium overlay of 50-100nm thickness.
Applications of a Phosphor Screen Scintillator include:
While Analytical Components are very experienced in working with P22G, P43, P46 & P47, we are also happy to discuss our range of phosphor types available. Coating thickness can vary greatly depending on the application, but we can offer coating thicknesses from a few microns up to a few hundred. We can supply phosphor screens with particle size ranging from 1.5um to 25um; typically smaller particle sizes are used for high-resolution screens, and larger particles are used for efficiency brightness.
Given that phosphor screens are extremely prone to damage from only the merest of touch, Analytical Components can provide screens which are coated through a process using potassium silicate, known as “waterglass” process, to improve is durability and resistance from human error.
Analytical Components can coat on a number of substrates ranging from Float and other glass types, Fibre Optic Plates (FOPS), Silicon to flexible materials such as Mylar.