65results about "Multiplier cathode arrangements" patented technology

The present invention provides a gamma-neutron detector based on mixtures of thermal neutron absorbers that produce heavy-particle emission following thermal capture. The detector consists of one or more thin screens embedded in transparent hydrogenous light guides, which also serve as a neutron moderator. The emitted particles interact with the scintillator screen and produce a high light output, which is collected by the light guides into a photomultiplier tube and produces a signal from which the neutrons are counted. Simultaneous gamma-ray detection is provided by replacing the light guide material with a plastic scintillator. The plastic scintillator serves as the gamma-ray detector, moderator and light guide. The neutrons and gamma-ray events are separated employing Pulse-Shape Discrimination (PSD). The detector can be used in several scanning configurations including portal, drive-through, drive-by, handheld and backpack, etc.

The present invention provides a gamma-neutron detector based on mixtures of thermal neutron absorbers that produce heavy-particle emission following thermal capture. In one configuration, B-10 based detector is used in a parallel electrode plate geometry that integrates neutron moderating sheets, such as polyethylene, on the back of the electrode plates to thermalize the neutrons and then detect them with high efficiency. The moderator can also be replaced with plastic scintillator sheets viewed with a large area photomultiplier tube to detect gamma-rays as well. The detector can be used in several scanning configurations including portal, drive-through, drive-by, handheld and backpack, etc.

An advanced image intensifier assembly provides enhanced functionality. A grounded photocathode provides shielding from electromagnetic interference, improving the ability to work in multiple light conditions. Bi-directional wireless communication and non-volatile storage allow critical information to be permanently stored and read wirelessly at a scanning station, easing in identification of units. Because bi-directional communication components can be embedded within an image intensifier assembly, existing end-user night vision devices can be upgraded by simply replacing the image intensifier assembly. For enhanced safety, a programmable shutdown capability is provided. This renders the device inoperative in the absence of continuous input, either wireless or manual, from an authorized operator, thus rendering the device useless if captured by enemy combatants. Finally, direct 1-volt operation enables the device to be powered by, for example, a single AA battery.

A photocathode having a UV glass substrate and a laminate composed of a SiO2 layer, a GaAlN layer, a Group III-V nitride semiconductor layer and an AlN buffer layer provided on the UV glass substrate in succession. The UV glass substrate, which absorbs infrared rays, can be heat treated at a high speed by photoheating. Further, the UV glass substrate, which is transparent to ultraviolet rays, permits ultraviolet rays to be introduced into the Group III-V nitride semiconductor layer where photoelectric conversion occurs.

A transmission type photocathode of the present invention comprises a light absorption layer 1 formed of diamond or a material containing diamond as a main component, a supporting frame 21 for reinforcing the mechanical strength of the light absorption layer 1, a first electrode 31 provided at the plane of incidence of the light absorption layer 1, and a second electrode 32 provided at the plane of emission of the light absorption layer 1. A voltage is applied between the plane of incidence and plane of emission of the light absorption layer 1 to form an electric field in the light absorption layer 1. When light to be detected is made incident and photoelectrons occur in the light absorption layer 1, the photoelectrons are accelerated to the plane of emission by the electric field formed in the light absorption layer 1, and emitted to the outside of the transmission type photocathode.

A semiconductor photocathode of the present invention is provided with: a support substrate 10; a photoelectric surface 30 which is formed of a plurality of semiconductor layers layered on this support substrate 10 and which emits photoelectrons from a photoelectron emitting surface 341 in response to the incidence of light to be detected; and a metal electrode 35 which is formed in film form so as to coat at least a portion of support substrate 10 and a portion of photoelectric surface 30 and which makes ohmic contact with the photoelectric surface, wherein metal electrode 30 in film form includes titanium and the electron affinity of photoelectron emitting surface 341, which is an exposed portion of photoelectric surface 30 without being coated with metal electrode 35 in film form, is in a negative condition.

The invention discloses a dynamic multi-stage serial connection coaxial butterfly-type channel dynode electron multiplier. The dynamic multi-stage serial connection coaxial butterfly-type channel dynode electron multiplier comprises a plurality of stages of butterfly-type dynodes sequentially distributed from inside to outside, an emission source, a voltage source and a drive device used for driving the multiple stages of butterfly-type dynodes to rotate, wherein the multiple stages of butterfly-type dynodes are sequentially arranged along a reflection path of electrons; each stage of butterfly-type dynode comprises a negative plate, a gate electrode and an arc support; the gate electrodes are of an annular structure; the cross section of each negative plate is of an arc structure; the circle centers of the negative plate in the multiple stages of butterfly-type dynodes coincide with a rotary shaft; the inner side faces of the negative plates are covered with reflection films; the negative plates are fixed on the arc surfaces of the corresponding arc supports; the gate electrodes are fixed on the lateral faces of the corresponding arc supports; one of each gate electrode is fixedly connected with one end of the corresponding negative plate; the voltage source comprises a power source and multiple resistors connected with the power source in series. The dynamic multi-stage serial connection coaxial butterfly-type channel dynode electron multiplier is long in service life, the actual use area of the negative plates is large, and the effective electron emissivity is high.

The invention discloses an automatic expansion focusing electrode for a photomultiplier tube and a photomultiplier tube, wherein the automatic expansion focusing electrode comprises an expansion support rod, a metal cloth, a fixing mechanism, a rotating shaft and a touch spring. The expansion support rod, the rotating shaft and the touch spring piece are one-to-one corresponded, and are arranged around the fixing mechanism; A plurality of expansion struts rotatably mounted along an edge of the fixing mechanism and about the rotational axis; The metal cloth is arranged around the central axis of the fixing mechanism in an initial state of wrinkle folding, and each expansion rod is fixedly connected with the wrinkle edge position of the metal cloth, so that the metal cloth can be unfolded with the movement of the expansion rod to enter an expanded state. The automatic expansion focusing pole of the invention can realize the expansion action of the automatic expansion focusing pole and realize the expansion of the radial dimension of the focusing pole.

The invention belongs to the technical field of photomultipliers. The invention discloses a high-quantum-efficiency low-thermal-emission double-alkali photocathode used for a photomultiplier and a preparation method thereof. The obtained double-alkali photocathode structure is formed by stacking a plurality of layers of alkali antimonide on a substrate in sequence, the composition of the alkali antimonide in the direction from the substrate to the outer surface of the double-alkali photocathode is in a rule that the antimony element is gradually reduced and the alkali metal element is gradually increased, and the quantum efficiency of the micro-channel plate type photomultiplier is improved; in the preparation process, the light current inflection point is controlled by adjusting the rateof increasing the current of an antimony ball in the first stage of simultaneous evaporation of potassium and antimony; by comprehensively regulating and controlling the change of antimony-off observation reflectivity in the second stage of simultaneous evaporation of potassium and antimony, the hot electron emission of the photocathode is reduced, so that the integral sensitivity of the double-alkali cathode is reduced, the noise of the micro-channel plate type photomultiplier is improved, and the process consistency is relatively good.

The invention belongs to the technical field of photomultipliers, particularly relates to a photocathode, and discloses a high-sensitivity K-Na-Cs-Sb reflective multi-alkali photocathode and a preparation method and system thereof. The alkali source assembly comprises three alkali sources, namely a K source, a Na source and a Cs source. The alkali source assembly is connected with the exhaust table through a tail pipe to obtain an ultrahigh vacuum degree. The side window type photomultiplier comprises a glass shell, a cathode and a plurality of multipliers. The cathode and the multipliers areconfigured to be metal sheets with certain radians, and the inner surfaces of the cathode and the multipliers are plated with metal antimony layers. The side window type photomultiplier is connected to the alkali source assembly through an exhaust tail pipe. The corresponding alkali source applies current to realize self-heating, and releases alkali metal vapor to react with the antimony layer toform a multi-alkali cathode structure. The introduction process of K, Na and Cs is monitored by monitoring changes of leakage current and photocurrent, the introduction amount of K, Na and Cs is accurately controlled, and the problem that the cathode sensitivity is low due to the fact that too much or too little K, Na and Cs are introduced is solved.

The invention belongs to the technical field of photomultipliers, and provides a high-temperature-uniformity air exhausting device for manufacturing micro-channel plate type photomultipliers. The device comprises a main machine table, a bottom plate, a bell jar removably mounted on the base plate, a lifting mechanism arranged on the bottom plate, a heating device which is arranged in a closed cavity formed by the bell jar and is used for heating photomultiplier glass spherical shells clamped on a three-station rotary worktable from the side part, the top part and middle gap position of the photomultiplier glass spherical shells, a control unit used for controlling the power of the heating device. With the high-temperature-uniformity air exhausting device for manufacturing the micro-channelplate type photomultiplier of the invention and a heating method adopted, three or more photomultipliers can be manufactured at the same time; the problem of poor temperature uniformity caused by non-uniform position distribution of the photomultiplier shells in the air exhausting device is solved; and heating and working efficiency is improved.

The invention relates to a photocathode having a structure that permits a decrease in the radiant sensitivity at low temperatures is suppressed so that the S/N ratio is improved. In the photocathode, a light absorbing layer is formed on the upper layer of a substrate. An electron emitting layer is formed on the upper layer of the light absorbing layer. A contact layer having a striped-shape is formed on the upper layer of the electron emitting layer. A surface electrode composed of metal is formed on the surface of the contact layer. The interval between bars in the contact layer is adjusted so as to become 0.2 μm or more but 2 μm or less.

The invention relates to a non-contact object surface charge photomultiplier tube amplifier, belonging to the technical field of signal detection. The principle is as follows: the intensity of incident light is determined by the number of photons passing through a unit vertical area in unit time, and if the number of photons passing through a metal surface in unit time increases, the number of times that photons collide with the electrons in the metal increases, the number of photons escaping from the metal surface in unit time increases, and the photocurrent increases; and if the intensity of incident light remains unchanged and the number of times that photons collide with the electrons in the metal increases due to increase in the number of charges on the metal surface, the number of photoelectrons escaping from the metal surface in unit time increases. The number of photoelectrons is multiplied constantly by a photomultiplier tube, and the number of electrons collected by the anode finally can be increased 104-108 times. Because of high sensitivity and low noise of the photomultiplier tube, weak charge signals on the surface of a sample can be detected. The non-contact object surface charge photomultiplier tube amplifier can be widely used in the field of charge detection.

Ultraviolet light incident from the side of a surface layer 5 passes through the surface layer 5 to reach an optical absorption layer 4. Light which reaches the optical absorption layer 4 is absorbed within the optical absorption layer 4, and photoelectrons are generated within the optical absorption layer 4. Photoelectrons diffuse within the optical absorption layer 4, and reach the interface between the optical absorption layer 4 and the surface layer 5. Because the energy band is curved in the vicinity of the interface between the optical absorption layer 4 and surface layer 5, the energy of the photoelectrons is larger than the electron affinity in the surface layer 5, and so photoelectrons are easily ejected to the outside. Here, the optical absorption layer 4 is formed from an Al_0.3Ga_0.7N layer with an Mg content concentration of not less than 2×10¹⁹ cm⁻³ but not more than 1×10²⁰ cm⁻³, so that a solar-blind type semiconductor photocathode 1 with high quantum efficiency is obtained.

The photomultiplier tube has: a cathode (3) that releases electrons by incident light; a multistage dynode (107) that multiplies the electrons released from the cathode (3); and an electron lens forming electrode (115), which Arranged at a predetermined position relative to the edge of the first dynode (107a) and the edge of the second dynode (107b), wherein the first dynode (107a) is located at the first stage from the cathode (3) , the second dynode (107b) is located at the second level from the cathode (3), and in the length direction of the first dynode (107a), the distance between the first dynode (107a) and the second dynode (107b) The equipotential surface in the space between is flattened. With this structure, the time resolution with respect to incident light can be improved.