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79-456: [REDACTED] Look up calice in Wiktionary, the free dictionary. Calice may refer to: CALICE (Calorimeter for Linear Collider Experiment), a research and development organization Calice (noble family)  [ de ] , an Austrian noble family Calice Becker (fl. 1990–2014), French perfumer Calice, an alternative name for

158-495: A 5- λ {\displaystyle \lambda } thick tail catcher to measure the hadronic shower leakage. The sampling calorimeter has been calibrated to get its signal vs. the incident particle energy dependence using test beams of different incident particle sorts with known energies in the range from 4 GeV to 120 GeV. The corrections for the calorimeter non-linearity and the external temperature influence have been taken into rooster. For test beams with energy 50 GeV

237-413: A cerium-doped lanthanum bromide , LaBr 3 (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 γ for LaBr 3 (Ce) versus 38 photons/keV γ for NaI(Tl) ), a fast response (16 ns for LaBr 3 (Ce) versus 230 ns for NaI(Tl) ), excellent linearity, and a very stable light output over

316-412: 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

395-798: A future TeV-scale e + e − {\displaystyle e^{+}e^{-}} machine, such as the ILC, demand extremely high performance calorimetry. This is best achieved using a finely segmented system that allows to reconstruct events using the so-called "particle flow approach" (PFA). The calorimeter systems for high energy physics experiments usually consist of three main subsystems: electromagnetic calorimeter (ECAL) to detect electromagnetic showers produced by electrons (or positrons) and photons, hadronic calorimeter (HCAL) to measure hadron-induced showers, and muon tracker (or so-called tail catcher) to identify highly penetrating particles such as muons . CALICE has developed prototypes of

474-422: A hundred 3 × 3 cm tiles in the center, surrounded by a large area covered with 6 × 6 cm tiles and finally enclosed by a strip of 12 × 12 cm tiles. These nearly 8000 tiles in total are read out individually by wavelength-shifting fibers which illuminate small silicon photomultipliers mounted on each tile and insensitive to large magnetic fields. The very important experimental part of this project

553-450: A one cubic-meter steel/scintillator sandwich sampling hadronic calorimeter called physics prototype for study series in various test particle beams . High granularity is achieved by 38 scintillator tile layers . Each layer is a 2-cm thick steel plate 90 × 90 cm followed by a 0.5-cm scintillator plate that consists of more than 200 scintillator tiles. The mosaic of the HCAL layers exhibits

632-612: 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: BGO , BaF 2 , CaF 2 (Eu) , ZnS(Ag) , CaWO 4 , CdWO 4 , YAG(Ce) ( Y 3 Al 5 O 12 (Ce) ), GSO , LSO . (For more examples, see also phosphors ). Newly developed products include LaCl 3 (Ce) , lanthanum chloride doped with cerium, as well as

711-409: A vibrational level. The singlet excitations immediately decay (< 10 ps) to the S state without the emission of radiation (internal degradation). The S state then decays to the ground state S 0 (typically to one of the vibrational levels above S 0 ) by emitting a scintillation photon . This is the prompt component or fluorescence . The transparency of the scintillator to the emitted photon

790-482: A whole by impurity centers. The latter then rapidly de-excite by emitting scintillation light (fast component). The activator impurities are typically chosen so that the emitted light is in the visible range or near-UV where photomultipliers are effective. The holes associated with electrons in the conduction band are independent from the latter. Those holes and electrons are captured successively by impurity centers exciting certain metastable states not accessible to

869-485: A wide range of temperatures. In addition LaBr 3 (Ce) offers a higher stopping power for γ rays (density of 5.08 g/cm versus 3.67 g/cm for NaI(Tl) ). LYSO ( Lu 1.8 Y 0.2 SiO 5 (Ce) ) has an even higher density (7.1 g/cm , 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,

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948-1019: 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 percentage of anthracene light output. These are liquid solutions of one or more organic scintillators in an organic solvent . The typical solutes are fluors such as p -terphenyl ( C 18 H 14 ), PBD ( C 20 H 14 N 2 O ), butyl PBD ( C 24 H 22 N 2 O ), PPO ( C 15 H 11 NO ), and wavelength shifter such as POPOP ( C 24 H 16 N 2 O ). 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

1027-459: Is also decreased via high density materials. This results in high segmentation of the detector and leads to better spatial resolution. Usually high density materials have heavy ions in the lattice (e.g., lead , cadmium ), significantly increasing the contribution of photoelectric effect (~Z ). The increased photo-fraction is important for some applications such as positron emission tomography . High stopping power for electromagnetic component of

1106-422: Is an area of intense research. Transitions made by the free valence electrons of the molecules are responsible for the production of scintillation light in organic crystals. These electrons are associated with the whole molecule rather than any particular atom and occupy the so-called - molecular orbitals . The ground state S 0 is a singlet state above which are the excited singlet states (S , S , ...),

1185-422: Is an electron): ≈40 photons/keV for NaI(Tl) , ~10 photons/keV for plastic scintillators, and ~8 photons/keV for bismuth germanate ( BGO ). Scintillation detectors are generally assumed to be linear. This assumption is based on two requirements: (1) that the light output of the scintillator is proportional to the energy of the incident radiation; (2) that the electrical pulse produced by the photomultiplier tube

1264-697: Is due to the fact that the energy of the photon is less than that required for an S 0 → S transition (the transition is usually being to a vibrational level above S 0 ). When one of the triplet states gets excited, it immediately decays to the T 0 state with no emission of radiation (internal degradation). Since the T 0  → S 0 transition is very improbable, the T 0 state instead decays by interacting with another T 0 molecule: T 0 + T 0 → S ∗ + S 0 + photons {\displaystyle T_{0}+T_{0}\rightarrow S^{*}+S_{0}+{\text{photons}}} and leaves one of

1343-544: Is essential to prevent self reabsorption for scintillators. More recently, a new material class first reported by Professor Biwu Ma's research group, called 0D organic metal halide hybrid (OMHH), an extension of the perovskite materials. This class of materials exhibits strong exciton binding of hundreds of meV, resulting in their high photoluminescent quantum efficiency of almost unity. Their large stoke shift and reabsorption-free properties make them desirable. Their potential applications for scintillators have been reported by

1422-407: Is essentially 100% for most scintillators. But because electrons can make large angle scatterings (sometimes backscatterings ), they can exit the detector without depositing their full energy in it. The back-scattering is a rapidly increasing function of the atomic number Z of the scintillator material. Organic scintillators, having a lower Z than inorganic crystals, are therefore best suited for

1501-471: Is maintained at cryogenic temperatures because mutual repulsion drives any additional electrons into the next higher available energy level, which is in the conduction band. The spectrum of photons from this process is centered at 930 nm (1.33 eV) and there are three other emission bands centered at 860, 1070, and 1335 nm from other minor processes. Each of these emission bands has a different luminosity and decay time. The high scintillation luminosity

1580-562: Is now in progress: a combined test beam program involving exposure of combined prototype calorimeter system to real particle beams from different accelerators and subsequent data analysis. In test beam studies, the Tile-HCAL with an effective thickness 4.5 nuclear interaction lengths ( λ {\displaystyle \lambda } ) is headed by an electromagnetic calorimeter (Silicon-Tungsten) near 1- λ {\displaystyle \lambda } in thickness and followed by

1659-561: Is observed and write about yields up to 200 000 ph/MeV. The quenching is attributed to the small e-h binding energy in the exciton that decreases for Cl to Br to I . Interestingly one may replace the organic MA group with Cs+ to obtain full inorganic CsPbX 3 halide perovskites. Depending on the Cl, Br, I content the triplet X-ray excited exciton emission can be tuned from 430 nm to 700 nm . One may also dilute Cs with Rb to obtain similar tuning. Above very recent developments demonstrate that

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1738-454: Is produced whenever an acceptor atom such as boron captures an ionization hole from the valence band and that hole recombines radiatively with one of the delocalized electrons. Unlike many other semiconductors, the delocalized electrons provided by the silicon are not “frozen out” at cryogenic temperatures. Above the Mott transition concentration of 8 × 10 free carriers per cm , the “metallic” state

1817-502: Is proportional to the emitted scintillation light. The linearity assumption is usually a good rough approximation, although deviations can occur (especially pronounced for particles heavier than the proton at low energies). Resistance and good behavior under high-temperature, high-vibration environments is especially important for applications such as oil exploration ( wireline logging , measurement while drilling). For most scintillators, light output and scintillation decay time depends on

1896-453: Is strong, the overall decay time constant varies with the type of incident particle. Such scintillators enable pulse shape discrimination, i.e., particle identification based on the decay characteristics of the PMT electric pulse. For instance, when BaF 2 is used, γ rays typically excite the fast component, while α particles excite the slow component: it is thus possible to identify them based on

1975-412: Is surprising because (1) with a refractive index of about 3.5, escape is inhibited by total internal reflection and (2) experiments at 90K report narrow-beam infrared absorption coefficients of several per cm. Recent Monte Carlo and Feynman path integral calculations have shown that the high luminosity could be explained if most of the narrow beam absorption is actually a novel optical scattering from

2054-419: Is the mechanism of energy absorption: energy is first absorbed by the solvent, then passed onto the scintillation solute (the details of the transfer are not clearly understood). The scintillation process in inorganic materials is due to the electronic band structure found in crystals and is not molecular in nature as is the case with organic scintillators. An incoming particle can excite an electron from

2133-415: Is the target in experiments to detect rare, low-energy electronic excitations from interacting dark matter. 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

2212-719: Is their hygroscopicity, a property which requires them to be housed in an airtight container to protect them from moisture. CsI(Tl) and BaF 2 are only slightly hygroscopic and do not usually need protection. CsF, NaI(Tl) , LaCl 3 (Ce) , LaBr 3 (Ce) are hygroscopic, while BGO , CaF 2 (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

2291-676: Is typically slower than in organic ones, ranging typically from 1.48 ns for ZnO(Ga) to 9000 ns for CaWO 4 . Exceptions are CsF (~5 ns), fast BaF 2 (0.7 ns; the slow component is at 630 ns), as well as the newer products ( LaCl 3 (Ce) , 28 ns; LaBr 3 (Ce) , 16 ns; LYSO , 41 ns). For the imaging application, one of the advantage of inorganic crystals is very high light yield. Some high light yield scintillators above 100,000 photons/MeV at 662 keV are very recently reported for LuI 3 (Ce) , SrI 2 (Eu) , and Cs 2 HfCl 6 . Many semiconductor scintillator phosphors are known, such as ZnS(Ag) (mentioned in

2370-578: 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

2449-493: Is ≈10 ns, their light output is however low, typically ≈30% of that of anthracene. Scintillation properties of organic-inorganic methylamonium (MA) lead halide perovskites under proton irradiation were first reported by Shibuya et al. in 2002 and the first γ-ray pulse height spectrum, although still with poor energy resolution, was reported on ( (C 6 H 5 (CH 2 ) 2 NH 3 ) 2 PbBr 4 ) by van Eijk et al. in 2008 . Birowosuto at al. studied

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2528-564: The calyx in cnidarians "Cálice", a song by Chico Buarque Calice Ligure , a commune in Italy Calice al Cornoviglio , municipality in the Province of La Spezia in the Italian region Liguria See also [ edit ] Chalice (disambiguation) Calyx (disambiguation) Topics referred to by the same term [REDACTED] This disambiguation page lists articles associated with

2607-519: The recoil proton in (n,p) reactions; materials rich in hydrogen , e.g. plastic scintillators, are therefore best suited for their detection. Slow neutrons rely on nuclear reactions such as the (n,γ) or (n,α) reactions, to produce ionization. Their mean free path is therefore quite large unless the scintillator material contains nuclides having a high cross section for these nuclear reactions such as Li or B. Materials such as LiI(Eu) or glass silicates are therefore particularly well-suited for

2686-429: The valence band to either the conduction band or the exciton band (located just below the conduction band and separated from the valence band by an energy gap ; see picture ). This leaves an associated hole behind, in the valence band. Impurities create electronic levels in the forbidden gap . The excitons are loosely bound electron-hole pairs which wander through the crystal lattice until they are captured as

2765-412: The PMT (typically ~30% at peak), and on the efficiency of light transmission and collection (which depends on the type of reflector material covering the scintillator and light guides, the length/shape of the light guides, any light absorption, etc.). The light output is often quantified as a number of scintillation photons produced per keV of deposited energy. Typical numbers are (when the incident particle

2844-416: The PMT window. Ruggedness and good behavior under high temperature may be desirable where resistance to vibration and high temperature is necessary (e.g., oil exploration). The practical choice of a scintillator material is usually a compromise among those properties to best fit a given application. Among the properties listed above, the light output is the most important, as it affects both the efficiency and

2923-413: 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 one of two phenomena: delayed fluorescence or phosphorescence . The correspondence depends on the type of transition and hence

3002-408: 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

3081-806: 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

3160-488: The array to be sensitive to single photons. 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

3239-517: The conduction electrons with a cross section of about 5 x 10 cm that allows scintillation photons to escape total internal reflection. This cross section is about 10 times larger than Thomson scattering but comparable to the optical cross section of the conduction electrons in a metal mirror. In gases, the scintillation process is due to the de-excitation of single atoms excited by the passage of an incoming particle (a very rapid process: ≈1 ns). Scintillation counters are usually not ideal for

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3318-526: The decay time of the PMT signal. 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 ( C 14 H 10 , decay time ≈30 ns), stilbene ( C 14 H 12 , 4.5 ns decay time), and naphthalene ( C 10 H 8 , few ns decay time). They are very durable, but their response

3397-526: The detection of gamma rays . The three basic ways that a gamma ray interacts with matter are: the photoelectric effect , Compton scattering , and pair production . The photon is completely absorbed in photoelectric effect and pair production, while only partial energy is deposited in any given Compton scattering. The cross section for the photoelectric process is proportional to Z , that for pair production proportional to Z , whereas Compton scattering goes roughly as Z . A high- Z material therefore favors

3476-551: The detection of heavy ions for three reasons: The reduction in light output is stronger for organics than for inorganic crystals. Therefore, where needed, inorganic crystals, e.g. CsI(Tl) , ZnS(Ag) (typically used in thin sheets as α-particle monitors), CaF 2 (Eu) , should be preferred to organic materials. Typical applications are α- survey instruments , dosimetry instruments, and heavy ion dE / dx detectors. Gaseous scintillators have also been used in nuclear physics experiments. The detection efficiency for electrons

3555-424: 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

3634-426: The detection of low-energy (< 10 MeV) beta particles . The situation is different for high energy electrons: since they mostly lose their energy by bremsstrahlung at the higher energies, a higher- Z material is better suited for the detection of the bremsstrahlung photon and the production of the electromagnetic shower which it can induce. High- Z materials, e.g. inorganic crystals, are best suited for

3713-468: The emission is due to radiative decay of self-trapped excitons. The scintillation process in GaAs doped with silicon and boron impurities is different from conventional scintillators in that the silicon n -type doping provides a built-in population of delocalized electrons at the bottom of the conduction band. Some of the boron impurity atoms reside on arsenic sites and serve as acceptors. A scintillation photon

3792-504: The energy reconstruction. The unprecedented granularity of the CALICE calorimeter prototype provides an opportunity to test the particle flow concept. These days the work is in progress to check the output quality of the PFA programs. Due to large amount of test beam data, it becomes possible to use real events instead of simulated ones as input information for that programs. Since in the test beams all

3871-464: The excitons. The delayed de-excitation of those metastable impurity states again results in scintillation light (slow component). BGO ( bismuth germanium oxide ) is a pure inorganic scintillator without any activator impurity. There, the scintillation process is due to an optical transition of the Bi ion, a major constituent of the crystal. In tungstate scintillators CaWO 4 and CdWO 4

3950-433: The fast (or prompt) and the slow (or delayed) decay constants. Many scintillators are characterized by 2 time components: one fast (or prompt), the other slow (or delayed). While the fast component usually dominates, the relative amplitude A and B of the two components depend on the scintillating material. Both of these components can also be a function of the energy loss dE / dx . In cases where this energy loss dependence

4029-576: The former two processes, enabling the detection of the full energy of the gamma ray. If the gamma rays are at higher energies (>5 MeV), pair production dominates. Since the neutron is not charged it does not interact via the Coulomb force and therefore does not ionize the scintillation material. It must first transfer some or all of its energy via the strong force to a charged atomic nucleus . The positively charged nucleus then produces ionization . Fast neutrons (generally >0.5 MeV ) primarily rely on

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4108-469: The harnessing of gamma-ray energy through the photovoltaic effect, for example in a nuclear battery . The use of a scintillator in conjunction with a photomultiplier tube finds wide use in hand-held survey meters used for detecting and measuring radioactive contamination and monitoring nuclear material. Scintillators generate light in fluorescent tubes, to convert the ultra-violet of the discharge into visible light. Scintillation detectors are also used in

4187-482: The history section), CdS(Ag), ZnO(Zn), ZnO(Ga), CdS(In), ZnSe(O), and ZnTe(O), but none of these are available as single crystals. CdS(Te) and ZnSe(Te) have been commercially available in single crystal form, but their luminosity is partially quenched at room temperature. GaAs(Si,B) is a recently discovered cryogenic semiconductor scintillator with high light output in the infra-red and apparently no afterglow. In combination with ultra-low noise cryogenic photodetectors it

4266-495: The ionizing radiation needs greater photo-fraction; this allows for a compact detector. High operating speed is needed for good resolution of spectra. Precision of time measurement with a scintillation detector is proportional to √ τ sc . Short decay times are important for the measurement of time intervals and for the operation in fast coincidence circuits. High density and fast response time can allow detection of rare events in particle physics. Particle energy deposited in

4345-403: The lowest triplet state (T 0 ), and its excited levels (T , T , ...). A fine structure corresponding to molecular vibrational modes is associated with each of those electron levels. The energy spacing between electron levels is ≈1 eV; the spacing between the vibrational levels is about 1/10 of that for electron levels. An incoming particle can excite either an electron level or

4424-489: The material of a scintillator is proportional to the scintillator's response. Charged particles, γ-quanta and ions have different slopes when their response is measured. Thus, scintillators could be used to identify various types of γ-quanta and particles in fluxes of mixed radiation. Another consideration of scintillators is the cost of producing them. Most crystal scintillators require high-purity chemicals and sometimes rare-earth metals that are fairly expensive. Not only are

4503-505: The materials an expenditure, but many crystals require expensive furnaces and almost six months of growth and analyzing time. Currently, other scintillators are being researched for reduced production cost. Several other properties are also desirable in a good detector scintillator: a low gamma output (i.e., a high efficiency for converting the energy of incident radiation into scintillation photons), transparency to its own scintillation light (for good light collection), efficient detection of

4582-406: The molecules in the S state, which then decays to S 0 with the release of a scintillation photon. Since the T 0 -T 0 interaction takes time, the scintillation light is delayed: this is the slow or delayed component (corresponding to delayed fluorescence). Sometimes, a direct T 0  → S 0 transition occurs (also delayed), and corresponds to the phenomenon of phosphorescence . Note that

4661-664: The naked eye measurement with the newly developed PMT . This was the birth of the modern scintillation detector. Scintillators are used by the American government as Homeland Security radiation detectors. Scintillators can also be used in particle detectors , new energy resource exploration, X-ray security, nuclear cameras, computed tomography and gas exploration. Other applications of scintillators include CT scanners and gamma cameras in medical diagnostics, and screens in older style CRT computer monitors and television sets. Scintillators have also been proposed as part of theoretical models for

4740-419: The necessity to seal the solution in an oxygen-free, airtight enclosure. 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

4819-576: The number of emitted scintillation photons N in a single scintillation event can often be described by linear superposition of one or two exponential decays. For two decays, we have the form: N = A exp ⁡ ( − t τ f ) + B exp ⁡ ( − t τ s ) {\displaystyle N=A\exp \left(-{\frac {t}{{\tau }_{f}}}\right)+B\exp \left(-{\frac {t}{{\tau }_{s}}}\right)} where τ f and τ s are

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4898-430: The observational difference between delayed-fluorescence and phosphorescence is the difference in the wavelengths of the emitted optical photon in an S  → S 0 transition versus a T 0  → S 0 transition. Organic scintillators can be dissolved in an organic solvent to form either a liquid or plastic scintillator. The scintillation process is the same as described for organic crystals (above); what differs

4977-425: The organic-inorganic and all inorganic Pb-halide perovskites have various interesting scintillation properties. However, the recent two-dimensional perovskite single crystals with light yields between 10 000 and 40 000 ph/MeV and decay times below 10 ns at room temperature will be more favorable as they may have much larger Stokes shift up to 200 nm in comparison with CsPbBr 3 quantum dot scintillators and this

5056-410: The particle that originally struck the scintillator. Vacuum photodiodes are similar but do not amplify the signal while silicon photodiodes, on the other hand, detect incoming photons by the excitation of charge carriers directly in the silicon. Silicon photomultipliers consist of an array of photodiodes which are reverse-biased with sufficient voltage to operate in avalanche mode , enabling each pixel of

5135-573: The particles are almost at the same coordinate position, artificial events are created consisting of several incoming particles separated by some distance in order to check if the PFA program can reconstruct the incoming particles correctly. Scintillator A scintillator ( / ˈ s ɪ n t ɪ l eɪ t ər / SIN -til-ay-ter ) 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

5214-411: The petroleum industry as detectors for Gamma Ray logs. There are many desired properties of scintillators, such as high density , fast operation speed, low cost , radiation hardness , production capability, and durability of operational parameters. High density reduces the material size of showers for high-energy γ-quanta and electrons. The range of Compton scattered photons for lower energy γ-rays

5293-426: 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

5372-448: The precision of incoming particle energy reconstruction was estimated to be near 4%. Given some number of unknown incoming particles, it is possible to reconstruct their energies using the picture of particle showers from the calorimeter. That picture has to be analyzed by a PFA program. In addition, novel deep analysis (DA) algorithms have been developed to separate different sorts of secondary particles inside showers in order to improve

5451-476: The radiation being studied, a high stopping power , good linearity over a wide range of energy, a short rise time for fast timing applications (e.g., coincidence measurements), a short decay time to reduce detector dead-time and accommodate high event rates, emission in a spectral range matching the spectral sensitivity of existing PMTs (although wavelength shifters can sometimes be used), an index of refraction near that of glass (≈1.5) to allow optimum coupling to

5530-423: The resolution of the detector (the efficiency is the ratio of detected particles to the total number of particles impinging upon the detector; the energy resolution is the ratio of the full width at half maximum of a given energy peak to the peak position, usually expressed in %). The light output is a strong function of the type of incident particle or photon and of its energy, which therefore strongly influences

5609-414: The same group, and others. In 2020,(C38H34P2)MnBr4 was reported to have a light yield up to 80 000 Photon/MeV despite its low Z compared to traditional all inorganic. Impressive light yields from other 0D OMHH have been reported. There is a great potential to realize new generation scintillators from this material class. However, they are limited by their relatively long response time in microseconds, which

5688-824: 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 scintillators are usually crystals grown in high temperature furnaces , for example, alkali metal halides , often with

5767-482: The scintillation properties of 3-D and 2-D layered perovskites under X-ray excitation. MAPbBr 3 ( CH 3 NH 3 PbBr 3 ) emits at 550 nm and MAPbI 3 ( CH 3 NH 3 PbI 3 ) at 750 nm which is attributed to exciton emission near the band gap of the compounds. In this first generation of Pb-halide perovskites the emission is strongly quenched at room temperature and less than 1 000 ph/MeV survive. At 10 K however intense emission

5846-441: The spectral sensitivity range of a particular PMT, or B to increase the neutron detection efficiency of the scintillation counter itself (since B has a high interaction cross section with thermal neutrons ). Newer approaches combine several solvents or load different metals to achieve identification of incident particles. For many liquids, dissolved oxygen can act as a quenching agent and lead to reduced light output, hence

5925-669: The temperature. This dependence can largely be ignored for room-temperature applications since it is usually weak. The dependence on the temperature is also weaker for organic scintillators than it is for inorganic crystals, such as NaI-Tl or BGO. Strong dependence of decay time on the temperature in BGO scintillator is used for remote monitoring of temperature in vacuum environment. The coupled PMTs also exhibit temperature sensitivity, and can be damaged if submitted to mechanical shock. Hence, high temperature rugged PMTs should be used for high-temperature, high-vibration applications. The time evolution of

6004-500: The three main calorimetric subsystems of a future detector: an ECAL followed by an HCAL and a tail catcher/muon tracker (TCMT), and is evaluating the performance of alternative technological solutions within this combined system. The collaboration studies the performance of such calorimeters within a long, detailed program for an ECAL and several options of high granular analogue and digital calorimeters with sensitive layers of gas or plastic scintillator . The Tile subgroup [2] has built

6083-522: The title Calice . If an internal link led you here, you may wish to change the link to point directly to the intended article. Retrieved from " https://en.wikipedia.org/w/index.php?title=Calice&oldid=1045964095 " Categories : Disambiguation pages Disambiguation pages with given-name-holder lists Hidden categories: Short description is different from Wikidata All article disambiguation pages All disambiguation pages CALICE The physics requirements of

6162-418: The type of scintillation material to be used for a particular application. The presence of quenching effects results in reduced light output (i.e., reduced scintillation efficiency). Quenching refers to all radiationless de‑excitation processes in which the excitation is degraded mainly to heat. The overall signal production efficiency of the detector, however, also depends on the quantum efficiency of

6241-561: The wavelength of the emitted optical photon . 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 . 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

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