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).

Bases
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.

Fluors
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.

Glasses
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.

Note:

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.

Features

  • 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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Infrared Dome Camera Pictures

The following snapshot pictures were taken using the Infrared Dome Camera in a section of warehouse.

This first picture was taken in our warehouse with the lights on.
IR Dome Day Mode Snapshot

The goal of the second picture was to demonstrate what this camera can do in a zero light condition. We turned all of the lights off in our headquarters warehouse (36 feet deep) and took the following image in zero light, for your consideration.

FROM:CCTV Camera Pros

Cleaning procedure for optics

Optics can be contaminated in many ways. Contamination can be kept to a minimum by returning the optics to their case or by covering the optics for protection from the outside environment. However, even with all these precautions, the optic will eventually accumulate dust, stains or some other form of contamination.
Inspection of Optical Surfaces.
During inspection, all optics must be handled in the cleanest area available (preferably a clean room or within a laminar flow bench). Proper equipment, like powder free clean room gloves or finger cots must be worn at all times to avoid grease and oils from being transferred to the optic. Lens tissue paper, dust free blowers, hemostats, cotton swabs, cotton tips, and reagent
grade acetone and methanol, will all be needed for cleaning optics. The acetone and methanol must be fairly fresh to avoid leaving any marks on the optics. Reagent Grade Isopropyl alcohol can also be used instead of acetone.
There are two ways in which an optic can be evaluated:
i.) If the optic is being used in a laser based system, contamination on the optic might cause the optic to scatter the laser light, thus reducing power and making the optic “glow”.
ii.) An optic can also be visually inspected by holding it below a bright light source and carefully viewing it at different angles. This will cause the light to scatter off the contamination enabling the viewer to see the various stains and dust particles.

Far Infrared Dome Benefits

Far Infrared Dome Benefits:
If you are looking for serious natural healing and wellness in the comfort of your home, look no further. The SOQI Dome’s advanced Japanese technology remains unsurpassed. The Far Infrared heat radiating from the Dome’s inner surface does more than warm and relax the body. Unlike regular heat, Far Infrared heat promotes healing of the body from the inside out.

Far Infrared heat benefits include increased circulation, pain relief, reduction in swelling and inflammation, serious toxin elimination (heavy metals), accelerated healing, and much more.

Far Infrared dry heat means you can remain clothed:
There is minimal to zero sweating so you can leave your clothes on, or wear loose clothing, or just your underwear. Traditional saunas heat up the air around you to a very high temperature creating ‘wet’ heat thereby causing the body to sweat profusely, whereas the Far Infrared sauna dome heat emits a gentle controlled far infrared ‘dry’ heat. Toxins are released into the blood stream and eliminated via urine and feces.

Distance is very Important:
The effects of far infrared ray, which travel in a straight line, weaken with distance, so the closer to the source of the far infrared rays your body is, the more impact they will have. The Far Infrared Dome was designed to be very close to the body for optimal health benefits.

Benefits of an Aspheric Lens

Spherical Aberration Correction
The most notable benefit of aspheric lenses is their ability to correct for spherical aberration, an optical effect which causes incident light rays to focus at different points when forming an image, creating a blur. Spherical aberration is commonly seen in spherical lenses, such as plano-convex or double-convex lens shapes, but aspheric lenses focus light to a small point, creating comparatively no blur and improving image quality. Spherical aberration is inherent in the basic shape of a spherical surface and is independent of alignment or manufacturing errors; in other words, a perfectly designed and manufactured spherical lens will still inherently exhibit spherical aberration. An aspheric lens can be designed to minimize aberration by adjusting the conic constant and aspheric coefficients of the curved surface of the lens.