A Visible Light Photon Counter (VLPC) is a photon counting photodetector based on impurity-band conduction in arsenic-doped silicon. They have high quantum efficiency and are able to detect single photons in the visible range of the electromagnetic spectrum. The ability to count the exact number of photons detected is extremely important for quantum key distribution.
Rockwell International's Science Center had previously announced the "Solid-State Photomultiplier" (SSPM), a wide-band (0.4–28 μm) detector. [1] In the late 1980s a collaboration – initially consisting of Rockwell and UCLA – began developing scintillating-fiber particle trackers for use at the Superconducting Super Collider, [2] [3] based on a dedicated variant of the SSPM that came to be known as the Visible Light Photon Counter. [4]
The operating principles are similar to APDs but based on impurity-band conduction. [5] The devices are made from arsenic-doped silicon and have an impurity band 50 meV below the conduction band, [6] resulting in a gain of 40000 to 80000 [5] [7] at a reverse bias of only a few volts (e.g. 7 V). [5] [note 1] The narrow bandgap reduces gain dispersion, resulting in a uniform response to each photon, and hence the output pulse height is proportional to the number of incident photons. VLPCs must operate at cryogenic temperatures (6–10 K). [5] They have a quantum efficiency of 85% at 565 nm [4] and a temporal resolution of several nanoseconds. [5]
VLPCs have been used extensively in the central tracking detector of the D0 experiment, [8] [9] and for muon beam-cooling studies for a muon collider (MICE). [7] They have also been evaluated for quantum information science. [6]
A photodiode is a semiconductor diode sensitive to photon radiation, such as visible light, infrared or ultraviolet radiation, X-rays and gamma rays. It produces an electrical current when it absorbs photons. This can be used for detection and measurement applications, or for the generation of electrical power in solar cells. Photodiodes are used in a wide range of applications throughout the electromagnetic spectrum from visible light photocells to gamma ray spectrometers.
Cathodoluminescence is an optical and electromagnetic phenomenon in which electrons impacting on a luminescent material such as a phosphor, cause the emission of photons which may have wavelengths in the visible spectrum. A familiar example is the generation of light by an electron beam scanning the phosphor-coated inner surface of the screen of a television that uses a cathode ray tube. Cathodoluminescence is the inverse of the photoelectric effect, in which electron emission is induced by irradiation with photons.
Gallium arsenide (GaAs) is a III-V direct band gap semiconductor with a zinc blende crystal structure.
Photomultiplier tubes (photomultipliers or PMTs for short) are extremely sensitive detectors of light in the ultraviolet, visible, and near-infrared ranges of the electromagnetic spectrum. They are members of the class of vacuum tubes, more specifically vacuum phototubes. These detectors multiply the current produced by incident light by as much as 100 million times or 108 (i.e., 160 dB), in multiple dynode stages, enabling (for example) individual photons to be detected when the incident flux of light is low.
A scintillation counter is an instrument for detecting and measuring ionizing radiation by using the excitation effect of incident radiation on a scintillating material, and detecting the resultant light pulses.
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. Sometimes, the excited state is metastable, so the relaxation back down from the excited state to lower states is delayed. The process then corresponds to one of two phenomena: delayed fluorescence or phosphorescence. The correspondence depends on the type of transition and hence the wavelength of the emitted optical photon.
In experimental and applied particle physics, nuclear physics, and nuclear engineering, a particle detector, also known as a radiation detector, is a device used to detect, track, and/or identify ionizing particles, such as those produced by nuclear decay, cosmic radiation, or reactions in a particle accelerator. Detectors can measure the particle energy and other attributes such as momentum, spin, charge, particle type, in addition to merely registering the presence of the particle.
A gamma camera (γ-camera), also called a scintillation camera or Anger camera, is a device used to image gamma radiation emitting radioisotopes, a technique known as scintigraphy. The applications of scintigraphy include early drug development and nuclear medical imaging to view and analyse images of the human body or the distribution of medically injected, inhaled, or ingested radionuclides emitting gamma rays.
Photodetectors, also called photosensors, are sensors of light or other electromagnetic radiation. There are a wide variety of photodetectors which may be classified by mechanism of detection, such as photoelectric or photochemical effects, or by various performance metrics, such as spectral response. Semiconductor-based photodetectors typically use a p–n junction that converts photons into charge. The absorbed photons make electron–hole pairs in the depletion region. Photodiodes and photo transistors are a few examples of photo detectors. Solar cells convert some of the light energy absorbed into electrical energy.
Gamma-ray spectroscopy is the qualitative study of the energy spectra of gamma-ray sources, such as in the nuclear industry, geochemical investigation, and astrophysics. Gamma-ray spectrometry, on the other hand, is the method used to acquire a quantitative spectrum measurement.
A gamma counter is an instrument to measure gamma radiation emitted by a radionuclide. Unlike survey meters, gamma counters are designed to measure small samples of radioactive material, typically with automated measurement and movement of multiple samples.
DELPHI was one of the four main detectors of the Large Electron–Positron Collider (LEP) at CERN, one of the largest particle accelerators ever made. Like the other three detectors, it recorded and analyzed the result of the collision between LEP's colliding particle beams. The specific focus of DELPHI was on particle identification, three-dimensional information, high granularity (detail), and precise vertex determination.
Neutron detection is the effective detection of neutrons entering a well-positioned detector. There are two key aspects to effective neutron detection: hardware and software. Detection hardware refers to the kind of neutron detector used and to the electronics used in the detection setup. Further, the hardware setup also defines key experimental parameters, such as source-detector distance, solid angle and detector shielding. Detection software consists of analysis tools that perform tasks such as graphical analysis to measure the number and energies of neutrons striking the detector.
A delayed-choice quantum eraser experiment, first performed by Yoon-Ho Kim, R. Yu, S. P. Kulik, Y. H. Shih and Marlan O. Scully, and reported in early 1998, is an elaboration on the quantum eraser experiment that incorporates concepts considered in John Archibald Wheeler's delayed-choice experiment. The experiment was designed to investigate peculiar consequences of the well-known double-slit experiment in quantum mechanics, as well as the consequences of quantum entanglement.
A neutrino detector is a physics apparatus which is designed to study neutrinos. Because neutrinos only weakly interact with other particles of matter, neutrino detectors must be very large to detect a significant number of neutrinos. Neutrino detectors are often built underground, to isolate the detector from cosmic rays and other background radiation. The field of neutrino astronomy is still very much in its infancy – the only confirmed extraterrestrial sources as of 2018 are the Sun and the supernova 1987A in the nearby Large Magellanic Cloud. Another likely source is the blazar TXS 0506+056 about 3.7 billion light years away. Neutrino observatories will "give astronomers fresh eyes with which to study the universe".
The NA62 experiment is a fixed-target particle physics experiment in the North Area of the SPS accelerator at CERN. The experiment was approved in February 2007. Data taking began in 2015, and the experiment is expected to become the first in the world to probe the decays of the charged kaon with probabilities down to 10−12. The experiment's spokesperson is Cristina Lazzeroni. The collaboration involves 333 individuals from 30 institutions and 13 countries around the world.
In phosphors and scintillators, the activator is the element added as dopant to the crystal of the material to create desired type of nonhomogeneities.
X-ray detectors are devices used to measure the flux, spatial distribution, spectrum, and/or other properties of X-rays.
Photon counting is a technique in which individual photons are counted using a single-photon detector (SPD). A single-photon detector emits a pulse of signal for each detected photon. The counting efficiency is determined by the quantum efficiency and the system's electronic losses.