Scintillation Crystals

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 absorbed energy in the form of light). Sometimes, the excited state is metastable, so the relaxation back down from the excited state to lower states is delayed (necessitating anywhere from a few nanoseconds to hours depending on the material): the process then corresponds to either one of two phenomena, depending on the type of transition and hence the wavelength of the emitted optical photon: delayed fluorescence or phosphorescence, also called after-glow.

A scintillation detector or scintillation counter is obtained when a scintillator is coupled to an electronic light sensor such as a photomultiplier tube (PMT), photodiode, or silicon photomultiplier (SiPM). PMTs absorb the light emitted by the scintillator and re-emit it in the form of electrons via the photoelectric effect. The subsequent multiplication of those electrons (sometimes called photo-electrons) results in an electrical pulse which can then be analyzed and yield meaningful information about the particle that originally struck the scintillator.

The first device which used a scintillator was built in 1903 by Sir William Crookes and used a ZnS screen. The scintillations produced by the screen were visible to the naked eye if viewed by a microscope in a darkened room; the device was known as a spinthariscope. The technique led to a number of important discoveries but was obviously tedious. Scintillators gained additional attention in 1944, when Curran and Baker replaced the naked eye measurement with the newly developed PMT. This was the birth of the modern scintillation detector.


Silicon (Si) Windows

  • Transmits wavelength range 1.2-7 μm
  • Ideal for weight sensitive applications
  • Cheaper than germanium and ZnSe

Silicon (Si) Windows manufactured from optical grade silicon are popular for the 1.2 – 7μm spectral region due to their low cost and low density. Due to its low density (half that of germanium or zinc selenide), silicon is ideal for weight sensitive applications, especially those in the MWIR thermal imaging  3 – 5μm region. Density is 2.329 g/cm3 and Knoop Hardness is 1150, making it harder and less brittle than germanium.

Materials Silicon crystals
Diameter Range ~ 300mm
Aperture >90%
Dimension Tolerance +0.0/-0.2mm
Thickness Tolerance +/-0.2mm
Surface Quality 80/50 S/D
Parallelism 1 arc minute
Chamfer 0.3-0.5mmx45degree
Coating AR/AR or DLC/AR


Scintillation Crystals

Light output (LO) is the coefficient of conversion of ionizing radiation into light energy. Having the highest LO,  NaI(Tl) crystal is the most popular scintillation material. Therefore, LO of NaI(Tl) is taken to be 100%. Light output of other scintillators is determined relative to that of NaI(Tl) (%). LO (Photon/MeV) is the number of visible photons produced in the bulk of scintillator under gamma radiation.
Scintillation Decay time is the time required for scintillation emission to decrease to e-1 of its maximum.
Energy resolution is the full width of distribution, measured at half of its maximum (FWHM), divided by the number of peak channel, and multiplied by 100. Usually Energy resolution is determined by using a 137Cs source. The above description is illustrated in Fig. 1. Energy resolution shows the ability of a detector to distinguish gamma-sources with slightly different energies, which is of great importance for gamma-spectroscopy.
Emission spectrum is the relative number of photons emitted by scintillator as a function of wavelength. The Emission spectrum is shown in Fig. 2. The intensity maximum corresponds to the Imax wavelength shown in the table. For coefficient detection of emitted photons, the maximum of PMT quantum efficiency should coincide with Imax.
Background is a quantity determined as a number of luminescent pulses emitted by radioactive substance within 1 second in the bulk of the scintillator with the weight of 1 kg.
Most scintillation crystals reveal a number of luminescent components. The main component corresponds to Decay time, however less intense and slower ones also exist. Commonly, the strength of these components is estimated by using the intensity of a scintillator’s glow, measured at specified time after the Decay time. Afterglow is the ratio of the intensity measured at this specified time (usually, after 6 ms) to the intensity of the main component measured at Decay time.

How are pixel arrays read

How is a pixel array read, such as in a LED TV, digital camera, microbolometer, etc. All of these things have an array of pixels that either transmit or receive. Each pixel must be read somehow, is this done with a multiplexer and do you need more and more multiplexers the more pixels you have. How many analog outputs does a multiplexer have? If you have a lot of pixels would you have to have multiplexers that are reading other multiplexers or just one big mulitiplexer would make more sense since your scanning an array. So then the analog outputs of the multiplexer would then connect to a micro controller and presumably the controller could tell an LED screen which scan goes in which LED pixel. So say the multiplexer scans sensor 11 and sends it back in a micro second or less the micro controller then displays that signal in the LED screen 11. So the controller would have to know the scan order to know where to display. Is this correct thinking? Are there solid state lab companies that can take a design and make a chip for you as a proto type?

FROM: physics forums

Types of scintillators

Organic crystals
Organic scintillators are aromatic hydrocarbon compounds which contain benzene ring structures interlinked in various ways. Their luminescence typically decays within a few nanoseconds.

Some organic scintillators are pure crystals. The most common types are anthracene(C14H10, decay time ≈30 ns), stilbene(C14H12, 4.5 ns decay time), and naphthalene (C10H8, few ns decay time). They are very durable, but their response is anisotropic (which spoils energy resolution when the source is not collimated), and they cannot be easily machined, nor can they be grown in large sizes; hence they are not very often used. Anthracene has the highest light output of all organic scintillators and is therefore chosen as a reference: the light outputs of other scintillators are sometimes expressed as a percent of anthracene light.

Organic liquids
These are liquid solutions of one or more organic scintillators in an organic solvent. The typical solutes are fluors such as p-terphenyl (C18H14), PBD (C20H14N2O), butyl PBD (C24H22N2O), PPO (C15H11NO), and wavelength shifter such as POPOP (C24H16N2O). The most widely used solvents are toluene, xylene, benzene, phenylcyclohexane, triethylbenzene, and decalin. Liquid scintillators are easily loaded with other additives such as wavelength shifters to match the spectral sensitivity range of a particular PMT, or 10B to increase the neutron detection efficiency of the scintillation counter itself (since 10B has a high interaction cross section with thermal neutrons). For many liquids, dissolved oxygen can act as a quenching agent and lead to reduced light output, hence the necessity to seal the solution in an oxygen-free, airtight enclosure.

Plastic scintillators
The term “plastic scintillator” typically refers to a scintillating material in which the primary fluorescent emitter, called a fluor, is suspended in the base, a solid polymer matrix. While this combination is typically accomplished through the dissolution of the fluor prior to bulk polymerization, the fluor is sometimes associated with the polymer directly, either covalently or through coordination, as is the case with many Li6 plastic scintillators. Polyethylene naphthalate has been found to exhibit scintillation by itself without any additives and is expected to replace existing plastic scintillators due to higher performance and lower price. The advantages of plastic scintillators include fairly high light output and a relatively quick signal, with a decay time of 2–4 nanoseconds, but perhaps the biggest advantage of plastic scintillators is their ability to be shaped, through the use of molds or other means, into almost any desired form with what is often a high degree of durability. Plastic scintillators are known to show light output saturation when the energy density is large (Birks’ Law).

The most common bases used in plastic scintillators are the aromatic plastics, polymers with aromatic rings as pendant groups along the polymer backbone, amongst which polyvinyltoluene (PVT) and polystyrene (PS) are the most prominent. While the base does fluoresce in the presence of ionizing radiation, its low yield and negligible transparency to its own emission make the use of fluors necessary in the construction of a practical scintillator. Aside from the aromatic plastics, the most common base is polymethylmethacrylate (PMMA), which carries two advantages over many other bases: high ultraviolet and visible light transparency and mechanical properties and higher durability with respect to brittleness. The lack of fluorescence associated with PMMA is often compensated through the addition of an aromatic co-solvent, usually naphthalene. A plastic scintillator based on PMMA in this way boasts transparency to its own radiation, helping to ensure uniform collection of light.

Other common bases include polyvinyl xylene (PVX) polymethyl, 2,4-dimethyl, 2,4,5-trimethyl styrenes, polyvinyl diphenyl, polyvinyl naphthalene, polyvinyl tetrahydronaphthalene, and copolymers of these and other bases.

Also known as luminophors, these compounds absorb the scintillation of the base and then emit at larger wavelength, effectively converting the ultraviolet radiation of the base into the more easily transferred visible light. Further increasing the attenuation length can be accomplished through the addition of a second fluor, referred to as a spectrum shifter or converter, often resulting in the emission of blue or green light.

Common fluors include polyphenyl hydrocarbons, oxazole and oxadiazole aryls, especially, n-terphenyl (PPP), 2,5-diphenyloxazole (PPO), 1,4-di-(5-phenyl-2-oxazolyl)-benzene (POPOP), 2-phenyl-5-(4-biphenylyl)-1,3,4-oxadiazole (PBD), and 2-(4’-tert-butylphenyl)-5-(4’’-biphenylyl)-1,3,4-oxadiazole (B-PBD).

Inorganic crystals
Inorganic scintillators are usually crystals grown in high temperature furnaces, for example, alkali metal halides, often with a small amount of activator impurity. The most widely used is NaI(Tl) (thallium-doped sodium iodide); its scintillation light is blue. Other inorganic alkali halide crystals are: CsI(Tl), CsI(Na), CsI(pure), CsF, KI(Tl), LiI(Eu). Some non-alkali crystals include: BaF2, CaF2(Eu), ZnS(Ag), CaWO4, CdWO4, YAG(Ce) (Y3Al5O
12(Ce)), GSO, LSO. (For more examples, see also phosphors).

Newly developed products include LaCl3(Ce), lanthanum chloride doped with cerium, as well as a cerium-doped lanthanum bromide, LaBr3(Ce). They are both very hygroscopic (i.e., damaged when exposed to moisture in the air) but offer excellent light output and energy resolution (63 photons/keV for LaBr3(Ce) versus 38 photons/keV γ for NaI(Tl)), a fast response (16 ns for LaBr3(Ce) versus 230 ns for NaI(Tl)[9]), excellent linearity, and a very stable light output over a wide range of temperatures. In addition LaBr3(Ce) offers a higher stopping power for γ rays (density of 5.08 g/cm3 versus 3.67 g/cm3 for NaI(Tl)[9]). LYSO (Lu1.8Y0.2SiO5(Ce)) has an even higher density (7.1 g/cm3, comparable to BGO), is non-hygroscopic, and has a higher light output than BGO (32 photons/keV γ), in addition to being rather fast (41 ns decay time versus 300 ns for BGO).

A disadvantage of some inorganic crystals, e.g., NaI, is their hygroscopicity, a property which requires them to be housed in an airtight container to protect them from moisture. CsI(Tl) and BaF2 are only slightly hygroscopic and do not usually need protection. CsF, NaI(Tl), LaCl3(Ce), LaBr3(Ce) are hygroscopic, while BGO, CaF2(Eu), LYSO, and YAG(Ce) are not.

Inorganic crystals can be cut to small sizes and arranged in an array configuration so as to provide position sensitivity. Such arrays are often used in medical physics or security applications to detect X-rays or γ rays: high-Z, high density materials (e.g. LYSO, BGO) are typically preferred for this type of applications.

Scintillation in inorganic crystals is typically slower than in organic ones, ranging typically from 1.48 ns for ZnO(Ga) to 9000 ns for CaWO4. Exceptions are CsF} (~5 ns), fast BaF2 (0.7 ns; the slow component is at 630 ns), as well as the newer products (LaCl3(Ce), 28 ns; LaBr3(Ce), 16 ns; LYSO, 41 ns).

Gaseous scintillators
Gaseous scintillators consist of nitrogen and the noble gases helium, argon, krypton, and xenon, with helium and xenon receiving the most attention. The scintillation process is due to the de-excitation of single atoms excited by the passage of an incoming particle. This de-excitation is very rapid (~1 ns), so the detector response is quite fast. Coating the walls of the container with a wavelength shifter is generally necessary as those gases typically emit in the ultraviolet and PMTs respond better to the visible blue-green region. In nuclear physics, gaseous detectors have been used to detect fission fragments or heavy charged particles.

The most common glass scintillators are cerium-activated lithium or boron silicates. Since both lithium and boron have large neutron cross-sections, glass detectors are particularly well suited to the detection of thermal (slow) neutrons. Lithium is more widely used than boron since it has a greater energy release on capturing a neutron and therefore greater light output. Glass scintillators are however sensitive to electrons and γ rays as well (pulse height discrimination can be used for particle identification). Being very robust, they are also well-suited to harsh environmental conditions. Their response time is ≈10 ns, their light output is however low, typically ≈30% of that of anthracene.

From Wikipedia, the free encyclopedia

DKDP (KD*P) Crystals – Potassium Dideuterium Phosphate Crystal

DKDP (KD*P) Crystals – Potassium Dideuterium Phosphate Crystal-laser component\ Nonlinear Crystals\ DKDP (KDP)

Potassium Dideuterium Phosphate (DKDP or KD*P ) are among the most widely-used commercial NLO’s crystals, characterized by good UV transmission, high damage threshold, and high birefringence, though their NLO coefficients are relatively low. They are usually used for doubling (SHG), tripling (THG) and quadrupling (FHG) of a Nd:YAG laser at the room temperature. In addition, they are also excellent electro-optic crystals with high electro-optic coefficients, makes it be widely used as electro-optical modulators, such as EO Q-switches, EO Pockels Cells, etc.


CO2 laser optics for cutting and etching signs

A line of OEM compatible replacement CO2 laser optics that come in several configurations for cutting and etching metal, plastic, or wood signs is available of Providence, Rhode Island.

ZnSe Optics for Sign-Making Lasers include configurations for 300W to 500W metal cutting lasers and others for engraving lasers with focal lengths from 2.0” to 7.5”, in 0.5” increments, for applications requiring clean, sharp detailed edges. These CO2 optics are available in 1.0” and 1.5” dia. sizes for working with metal, plastic, or wood.

In stock for 24 Hour shipment for use as field replacement optics, ZnSe Optics for Sign-Making Lasers are optimized for 10.6 microns and conform to ISO-10110 specifications for optical elements. Silicon turning mirrors with better than 99.5% reflectance and single- or dual-band coatings are also offered.

ZnSe Optics for Sign-Making Lasers are priced according to size and quantity. Price quotations are available upon request.

FROM:Laser Research Optic

Silicon wafers, substrates and specimen supports

Polished silicon is an excellent substrate for imaging experiments, nanotechnology and micro-fabrication applications. For imaging applications, it is an ideal sample substrate for small particles due to the low background signal of the highly polished surface. For biological applications silicon resembles glass, which makes it a suitable support for growing and/or mounting cells.

The silicon wafers and chips are all P-type, doped with B to provide excellent conductivity for SEM, FIB and STM applications. It is available as wafers, diced wafers or as smaller chips (pieces). The silicon wafer and chips all have a <100> orientation. Cleaving of the wafers to the desired size with a <100> orientation wafers is straight forward and simple.

Micro-Tec silicon wafer substrates from Micro to Nano are a useful flat substrate for SEM imaging of particles due to the low background and can also be used as sample substrates, micro-fabrication, substrate for thin film research or biological substrates. Micro-Tec Si wafers are packed in a wafer carrier tray for protection. The diced wafer supplied on wafer adhesive disc and packed between two plastic sheets for protection. The Si chips can be easily lift off the adhesive sheet.

Wafers and Substrates

SAW crystals and wafers, Film substrates for HTSC (high temperature super conductivity), Magnet and Ferroelectricity and semiconductor applications, crystal wafers and substrate for semiconductors and ceramic substrates are offered in Hangzhou Shalom EO. Besides the customized wafers or substrates for your special applications, a variety model of typical or standard wafers and substrates are available upon your choice in fast delivery and low cost.

A wafer, also called a slice or substrate, is a thin slice of semiconductor material, such as a crystalline silicon, used in electronics for the fabrication of integrated circuits and in photovoltaics for conventional, wafer-based solar cells. The wafer serves as the substrate for microelectronic devices built in and over the wafer and undergoes many microfabrication process steps such as doping or ion implantation, etching, deposition of various materials, and photolithographic patterning. Finally, the individual microcircuits are separated (dicing) and packaged.

Side-hole type(SC1107)

  • Low background
  • High detection efficiency

The side-hole type NaI(Tl) scintillator is a detector with a side-hole passing vertically through the axis of the cylindrical NaI(Tl) crystal.
It is housed in aluminum cases and, for measurements, light output can be obtained from an optical window mounted on one or both sides of the edges while passing the specimen through the side-hole.


  • High detection efficiency
  • Low background

Application Notes

  1. Environmental Monitoring of nuclear radiation

Nuclear radiation exist universally in our daily life environment, when the radiation intensity higher than security standard, it would be harmful or even lethal to human beings. For its excellent scintillating properties, NaI(Tl) crystals are widely used to make the detectors to monitor nuclear radiation in the industrial and daily life environment, wide field and space.

  1. Nuclear medicine

NaI(Tl) crystals are widely used in the nuclear imaging technology, such as the isotope therapeutic apparatus, Gamma ray cameras ect.. Nuclear imaging is high in sensitivity and accurate in testing results, the method is easy and secure.

  1. Industrial CT and security inspection

The NaI(Tl) are used in the metallurgy industrial to test the speed of metal liquid, to test the thickness of the steel plates, they are also used in the level sensors or switches for solid or liquids. Some security inspection instruments use the NaI(Tl) crystals to test the explosive materials.

  1. Well logging

The NaI(Tl) crystals detect the Gamma ray in the well, by the analysis of the spectrum of the detected scintillating light, the concentration and distribution of the uranium (U), potassium (K) and thorium (Th) in the stratum can be calculated, and the well can be evaluated. NaI(Tl) crystals has high light output and insensitive to temperature change, it has been the first choice for the well logging applications.

scintillators\NaI(Tl) Scintillators\Side-hole type(SC1107)

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