140 results about "Dynode" patented technology

An improved electron multiplier bias network that limits the response of the multiplier when the multiplier is faced with very large input signals, but then permits the multiplier to recover quickly following the large input signal. In one aspect, this invention provides an electron multiplier, having a cathode that emits electrons in response to receiving a particle, wherein the particle is one of a charged particle, a neutral particle, or a photon; an ordered chain of dynodes wherein each dynode receives electrons from a preceding dynode and emits a larger number of electrons to be received by the next dynode in the chain, wherein the first dynode of the ordered chain of dynodes receives electrons emitted by the cathode; an anode that collects the electrons emitted by the last dynode of the ordered chain of dynodes; a biasing system that biases each dynode of the ordered chain of dynodes to a specific potential; a set of charge reservoirs, wherein each charge reservoir of the set of charge reservoirs is connected with one of the dynodes of the ordered chain of dynodes; and an isolating element placed between one of the dynodes and its corresponding charge reservoir, where the isolating element is configured to control the response of the electron multiplier when the multiplier receives a large input signal, so as to permit the multiplier to enter into and exit from saturation in a controlled and rapid manner.

Disclosed herein is a PhotoMultiplier Tube (PMT) designed for use with a surface inspection system such as the Surfscan system, which operates at 266 nm wavelength. The inventive PMT is high efficiency, low noise, and low gain, a combination of features that is specific to the application and contrary to the features of PMT's in the art. The inventive PMT is designed to be tuned to a specific narrow band wavelength of incident light, thereby optimizing the QE at that wavelength. It is further designed to combine a small number of dynodes each having substantially higher secondary electron gain than typical dynodes. By designing the PMT in this way, the excess noise factor is dramatically reduced, yielding a much improved S/N, while still maintaining the overall PMT gain in the lower range suitable for use in a surface inspection system.

A novel electron multiplier that regulates in real time the gain of downstream dynodes as the instrument receives input signals is introduced. In particular, the methods, electron multiplier structures, and coupled control circuits of the present invention enable a resultant on the fly control signal to be generated upon receiving a predetermined threshold detection signal so as to enable the voltage regulation of one or more downstream dynodes near the output of the device. Accordingly, such a novel design, as presented herein, prevents the dynodes near the output of the instrument from being exposed to deleterious current pulses that can accelerate the aging process of the dynode structures that are essential to the device.

An integrated micro-photomultiplier is disclosed which employs sub-micron-wide channels for electron amplification. These channels are created with standard lithographic and planar-fabrication techniques, and sealed with a vacuum-deposition process. A photocathode, continuous dynode, anode and signal-collector are fabricated along the channels. This photomultiplier design obviates the needs for through-substrate etching, and mechanical assembly of separate layers. Because large-scale-integration techniques can be used to fabricate multiple micro-photomultipliers, significant reductions in device cost and size are expected. The integrated micro-photomultiplier is useful for high-speed, low-light-level optical detection, and may find applications in optical communications, visible or infrared imaging, and chemical or biological sensing.

Electrons are prevented from being made incident onto an insulation part between dynodes to improve a withstand voltage. The photomultiplier tube 1 is provided with a casing having a glass substrate 40 on which a main surface 40a made with an insulating material is formed, dynodes 31 constituted with a 1^st stage to an N^th stage (N denotes an integer of 2 or more) which are arrayed so as to be spaced away sequentially from a first end side to a second end side on the main surface 40a, a photocathode 22 which is installed on the first end side so as to be spaced away from the 1^st stage dynode 31a to emit photoelectrons, and an anode part 32 which is installed on the second end side so as to be spaced away from the N^th stage dynode 31j, taking out multiplied electrons as a signal, in which a groove 44, the surface of which is made with an insulating material, is formed between two adjacent dynodes 31 on the main surface 40a of the glass substrate 40, and the 1^st stage to the N^th stage dynodes 31 are fixed on raised parts 45 adjacent to the grooves 44 on the glass substrate 40.

An ion detector includes an ion input face, a Faraday cup, an ion-to-electron converter dynode, two ion deflection electrodes, an electron multiplier portion, and an anode. The ion input face is formed with an ion input opening. The Faraday cup has an ion collection surface that confronts the ion input opening. The ion-to-electron converter dynode is disposed to one side with respect to the Faraday cup and the ion input opening and has a conversion surface that converts impinging ions into electrons. The two ion deflection electrodes generate an electron lens that attracts and focuses ions from the ion input opening toward the conversion surface of the ion-to-electron converter dynode. The electron multiplier portion receives and multiplies the electrons from the ion-to-electron converter dynode, and includes a plurality of dynodes that multiply electrons one after the other. The plurality of dynodes are juxtaposed in an arc-shape around the Faraday cup. The anode receives electrons from the electron multiplier portion and outputs a signal that corresponds to the amount of input ions.

A photomultiplier excellent in vibration resistance and improved in pulse linearity characteristic and time-response. The fourth, and sixth to ninth dynodes (Dy4, Dy6 to Dy9) have a similar shape to that of the second dynode (Dy2). The third and fifth dynodes (dy3, Dy5) are smaller than the dynode (Dy2). The first to tenth dynodes (Dy1 to Dy10) are so arranged that the dynode inner space path defined between opposed dynodes is perpendicular to the tube axis (X). The anode (A) is a mesh anode (A), and is opposed to the dynode (Dy2) with respect to the tube axis (X).

An ion detector for detecting positive ions and negative ions, includes a housing provided with an ion entrance to make the positive ions and the negative ions enter, a conversion dynode which is disposed in the housing and to which a negative potential is applied, a scintillator which is disposed in the housing and has an electron incident surface which is opposed to the conversion dynode and into which secondary electrons emitted from the conversion dynode are made incident, a conductive layer which is formed on the electron incident surface and to which a positive potential is applied, and a photodetector which detects light emitted by the scintillator in response to incidence of the secondary electrons.

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.

Every time a target sample is injected from an injector (12) of an LC unit (1) and a mass spectrometry for a target component in the sample is performed, a CD voltage applied to a conversion dynode of an ion detector (29) is switched. For each of the multiple CD-voltage levels, a data collector (32) collects noise data during a period of time where no component is present and intensity data of an ion originating from the target component, while the SN ratio calculator (33) calculates an SN ratio. After the actual measurement is completed, an optimum CD voltage determiner (34) compares the SN ratios calculated for each CD voltage, finds the CD voltage which gives the highest SN ratio, and stores this voltage in an optimum CD voltage memory (42) as an optimum CD voltage for the analysis conditions at that point in time and for the m/z of the analysis target. According to this method, even when the flow rate of the mobile phase is particularly high or when a hard-to-vaporize mobile phase is used, the CD voltage is appropriately set and a detection signal is obtained with high SN ratios.

The invention discloses an accelerated degradation test method of a multistage separation type dynode electron multiplier, which comprises the following steps: 1) placing at least five electron multiplier samples in a sealed container with binding posts, connecting electrodes of the electron multipliers with the corresponding binding posts, pumping the sealed container and maintaining vacuum; 2) respectively imposing at least three groups of incident particle flow strengths and working voltage values with different levels but higher than the normal using level on all the electron multiplier samples; 3) utilizing a milli-ampere current meter for carrying out continuous monitoring on the output current of all the electron multipliers; dividing the output current by the incident particle flow strength, converting into gain data and recording; and 4) utilizing a computer for processing the recorded gain data of the electron multipliers, and obtaining the predicted result of the service life.

An apparatus and method are disclosed for efficient detection of ions ejected from a quadrupolar ion trap, in which the ions are ejected as first and second groups of ions having different directions. The first and second groups of ions are received by a conversion dynode structure, which responsively emits secondary particles that are directed to a shared detector, such as an electron multiplier. The conversion dynode structure may be implemented as a common dynode or as two dynodes (or sets of dynodes), with each dynode positioned to receive one of the groups of ions.

The invention discloses a pollution-free electron multiplier assembly system and an assembly method thereof. In the scheme, a vacuum pumping system and a gas purifying system are used for maintaining working pressure and a gas environment all the time during assembly, so that an electron multiplier assembly process is conducted in a non-atmospheric environment, and pollution of the atmosphere to a dynode secondary electron emission surface can be reduced. Moreover, dynodes can be protected by continuously-flowing nitrogen flow. Additionally, all parts of an electron multiplier enter a main cabinet from a transition bin, the assembled electron multiplier is conveyed out of the main cabinet from the transition bin, and the transition bin is subjected to air purification before the parts in the transition bin enter the main cabinet, so that removing gas impurities carried by the parts in advance is guaranteed, and cleanliness of the working environment of the main cabinet is further guaranteed.

The invention discloses a magnification-adjustable PMT voltage division circuit comprising a photomultiplier with multiple dynodes. Each dynode is connected with an RC bias circuit which consists of a voltage division resistor and a capacitor which are connected in parallel. The voltage division resistors of two adjacent dynodes are sequentially connected in series. At least one dynode is provided with a photoelectric coupler of which the output end is connected in parallel to the voltage division resistor of the dynode and the input end is connected with the output end of an operational amplifier. According to the magnification-adjustable PMT voltage division circuit provided by the invention, the photoelectric coupler is arranged on one dynode, and the current output of the photoelectric coupler is controlled by the operational amplifier, so that the gain of the PMT can be adjusted conveniently and flexibly. The magnification-adjustable PMT voltage division circuit of the invention is simple in structure, and has the characteristics of stable gain, low power consumption, fast recovery, and the like.

A process of fabricating a discrete-dynode electron multiplier (DDEM) including the steps of mounting an insulator block to a conductor block, and forming a series of ion-optics geometrical structures in the conductor block, each ion-optics geometrical structure having a smallest dimension of less than 1 millimeter. The forming step may be performed by electrical discharge machining (EDM), laser cutting, and/or water jet cutting.

An ion detector 1A for detecting positive ions is provided with a chamber 2 having an ion entrance 3 which allows positive ions to enter, a conversion dynode 9 which is disposed in the chamber 2 and to which a negative potential is applied, and an avalanche photodiode 30 that is disposed in the chamber 2 and has an electron incident surface 30a which is opposed to the conversion dynode 9 and also into which secondary electrons emitted from the conversion dynode 9 are made incident. The electron incident surface 30a is located closer to the conversion dynode 9 than a positioning part 14 which supports the avalanche photodiode 30 in the grounded chamber 2.

The invention discloses a large-area photomultiplier with a hybrid multiplication system. The large-area photomultiplier comprises a vacuum glass container, a photocathode, the electron multiplicationsystem, an anode and a power supply electrode. The photocathode, the electron multiplication system and the anode are arranged in the vacuum glass container, the anode penetrates through the vacuum glass container through a signal lead and is connected with an external circuit, and the power supply electrode penetrates through the vacuum glass container through a power line and is connected withan external power supply circuit. The photocathode covers a whole inner surface of the vacuum glass container except a handle port. The multiplication system is arranged at an internal handle port ofthe vacuum glass container, comprises a first-stage spherical dynode and a second-stage micro-channel plate component, and can receive photoelectrons generated by the photocathode in all directions and generate multiplication electrons. The photomultiplier has advantages of a large photocathode coverage area and high photoelectron collection efficiency.

The invention provides an apparatus for connecting a quadrupole rod analyzer and a 3D ion trap analyzer in series. The apparatus comprises a quadrupole rod analyzer, post-quads, a gate electrode, a 3D ion trap analyzer, a protective electrode, a dynode, and a detector which are successively disposed. The apparatus uses the post-quads behind the quadrupole rod analyzer to cool ions on a central axis for certain time and to lengthen the effective length of the quadrupole rod analyzer for reducing the interference of an edge field, and uses the gate electrode in order to preliminarily accelerate and focus ion passing and to enhance the stability and the directionality of outputted ions. Therefore, the ions are easy to pass through an end cover electrode hole of the 3D ion trap or are stopped from passing in order to cooperate with the normal operation of the apparatus. In addition, the efficiency for entering the 3D ion trap of the ions is increased by enlarging the size of the end cover electrode hole or applying a stainless steel net to the end cover electrode hole.

Described here is a detector for measuring heavy mass ions with high sensitivity and low saturation for time-of-flight mass spectrometry and a detector housing for selecting between multiple detectors. It relates to sensitive measuring methods of large masses in the range of about ten thousand to a few million atomic mass units. Specifically it relates to a conversion dynode in a specifically insolated geometry followed by a discrete dynode secondary electron multiplier specifically modified to decrease electron saturation and electronic ringing. Conversion dynode detectors have been used before for time-of-flight mass spectrometry and compared to direct detection with electron multipliers they exhibit superior sensitivity for high-mass, slow-moving macromolecular ions. Using a conversion dynode specifically insolated to a common ground plane has the added capabilities of allowing an increased voltage to be applied to the conversion dynode while maintaining a minimum distance between the conversion dynode and the front of the electron multiplier. This creates faster ion flight time for the secondary ions produced within the detector allowing for higher time resolution and sensitivity from the detector. Also, by adding capacitance as charge buffers to the last few electrodes of a discrete dynode electron multiplier used as a secondary electron multiplier, saturation can be greatly reduced or avoided, which is often a major problem when measuring samples with ions covering a broad mass range. The detector housing described allows multiple detectors to be selected without breaking the vacuum. By keeping all moving mechanical parts inside the vacuum, a more simple, robust and cost effective design can be realized which provides a platform for measuring ions using different detector designs.