Improved TOF Qualitative Measurement Using a Multi-Channel Detector

Abstract

Maintain the resolution of a TOF mass analyzer despite a loss of resolution in one or more channels of a multi-channel ion detection system by selecting the highest resolution channels for qualitative analysis. Ion packets impinging on the multi-channel detector are converted into multiplied electrons and emitted from two or more segmented electrodes corresponding to impacts in different regions across the length of the detector. For each ion packet, the electrons received by each of the two or more segmented electrodes are converted into digital values in channels of a multi-channel digitizer, thereby generating digital values for at least two or more channels. Qualitative information regarding the ion packet is calculated using digital values from a predetermined subset of one or more channels known to provide the highest resolution among at least two or more channels.

Description

[0001] Related Applications

[0002] This application claims the benefit of U.S. Provisional Patent Application Serial No. 62 / 834,234, filed on April 15, 2019, the content of which is incorporated herein by reference in its entirety. Technical Field

[0003] The teachings herein relate to an ion detection system for a time-of-flight (TOF) mass analyzer or mass spectrometer. More specifically, the teachings herein relate to a multi-channel ion detection system that uses the signal intensity detected in the highest resolution channel for qualitative analysis but uses the signal intensities of the highest resolution channel and lower resolution channels for quantitative analysis.

[0004] The systems and methods disclosed herein are also implemented in conjunction with a processor, a controller, a microcontroller, or a computer system (such as Figure 1 the computer system of Background Art

[0005] Currently, some conventional TOF mass analyzers use an ion detection system including a four-channel digitizer. For example, the four-channel digitizer can include a time-to-digital converter (TDC) or an analog-to-digital converter (ADC). The multi-channel ion detection system provides two main advantages: improved resolution through independent calibration of the channels (also known as channel alignment) and enhanced dynamic range.

[0006] The use of analog detection can, in principle, replace the need for multiple channels in terms of dynamic range, which can also result in better time resolution of the ADC. However, the advantage of channel alignment will be lost. This can be partially compensated for by various means of tilting the ion packet or the detector itself, but it does not eliminate the adverse effect of ion packet curvature on resolution. Therefore, a four-channel ADC has been traditionally used.

[0007] The resolution on a TOF mass analyzer is a key driver of instrument performance. In a TOF ion detection system, resolution essentially refers to how well the distance between ion packets can be measured. In other words, the highest resolution will be the minimum distance between two ion packets that can still resolve two different ion packets.

[0008] Unfortunately, over time, the resolution of a TOF mass analyzer can degrade until it is no longer acceptable to the customer. For a multi-channel TOF mass analyzer, the resolution of some channels can degrade faster and more than that of other channels. For example, in a four-channel TOF mass analyzer, the resolution measured by the two channels receiving data from the two outermost electrodes typically degrades faster than that measured by the two channels receiving data from the two innermost electrodes.

[0009] First, simply discarding data from any channel with reduced resolution might seem like a solution to this problem. However, discarding the signal from even a single channel can reduce the overall sensitivity of the TOF mass analyzer and defeat the purpose of using a multi-channel ion detection system.

[0010] As a result, additional systems and methods are needed to address the problem of reduced resolution in some channels of the multi-channel ion detection system of a TOF mass analyzer. Summary of the Invention

[0011] A system, method, and computer program product are disclosed for maintaining the resolution of a TOF mass analyzer despite a loss of resolution in one or more channels of the multi-channel ion detection system of the TOF mass analyzer. The system includes a multi-channel detector and electron multiplier, a multi-channel digitizer, and a processor.

[0012] The multi-channel detector and electron multiplier are struck by an ion packet of the TOF mass analyzer. The ion packet strikes a first side of the multi-channel detector and electron multiplier. The multi-channel detector and electron multiplier convert the strike into multiplied electrons and emit the multiplied electrons from two or more segmented electrodes on a second side of the multi-channel detector and electron multiplier. Each of the two or more segmented electrodes corresponds to strikes in different regions across the length of the first side and emits electrons based on those strikes.

[0013] The multi-channel digitizer is electrically connected to the two or more segmented electrodes. The multi-channel digitizer converts the electrons received from each of the two or more segmented electrodes into digital values in channels of the multi-channel digitizer for each ion packet in the ion packet.

[0014] The processor receives digital values from at least two or more channels of the multi-channel digitizer. The processor uses digital values from a predetermined subset of one or more channels of the at least two or more channels to calculate qualitative information about the ion packet. A predetermined subset of one or more channels is known to provide the highest resolution of the at least two or more channels. The processor can also use the digital values of the at least two or more channels to calculate quantitative information about the ion packet.

[0015] These and other features of the applicant's teachings are set forth herein. Brief Description of the Drawings

[0016] Those skilled in the art will understand that the drawings described below are for illustrative purposes only. The drawings are not intended to limit the scope of this teaching in any way.

[0017] Figure 1 is a block diagram of a computer system on which embodiments of this teaching can be implemented.

[0018] Figure 2 is a side view of a time-of-flight (TOF) ion detection system, showing exemplary ion packets, each having an ideal shape and an ideal orientation just before they impinge on the microchannel plate (MCP) of the TOF ion detection system.

[0019] Figure 3 is a side view of a TOF ion detection system, showing exemplary ion packets, each having an ideal shape and a non-ideal orientation just before they impinge on the MCP of the TOF ion detection system.

[0020] Figure 4 is a side view of a TOF ion detection system, showing exemplary ion packets, each having a non-ideal shape and an ideal orientation just before they impinge on the MCP of the TOF ion detection system.

[0021] Figure 5 is a side view of a TOF ion detection system, showing how four electrodes and a four-channel digitizer are used to obtain digitized signals of exemplary ion packets each having a non-ideal shape to improve resolution.

[0022] Figure 6 is Figure 5 a front view of the impact side of the MCP of , showing ion packets impinging on the MCP in a rectangular pattern.

[0023] Figure 7 is Figure 5 a front view of the four electrodes of .

[0024] Figure 8 is an exemplary series of time plots, showing how to align or combine measurements from the four channels of the four-channel digitizer in Figure 5 to compensate for the non-ideal shape of the ion packets and improve the overall resolution of the ion detection system.

[0025] Figure 9 is Figure 5 a side view of the same TOF ion detection system as shown in , where exemplary ion packets overlap.

[0026] Figure 10 is an exemplary series of time plots, showing how to align or combine measurements from the four channels of the four-channel digitizer in Figure 9 to compensate for the non-ideal shape of the ion packets and improve the overall resolution of the ion detection system, even when the ion packets overlap.

[0027] Figure 11 is an exemplary series of time plots according to various embodiments, showing measurements from Figure 5How can the measurement results of the four channels of the four-channel digitizer in [[]] vary in resolution?

[0028] Figure 12 is an exemplary series of timing diagrams according to various embodiments, showing how, when the measurement results from the four channels vary in resolution, the measurement results from Figure 5 the four channels of the four-channel digitizer in [[]] are used for qualitative and quantitative analysis.

[0029] Figure 13 is an exemplary diagram of a multi-channel ion detection system for a TOF mass analyzer according to various embodiments, which maintains the resolution of the TOF mass analyzer despite a loss of resolution in one or more channels.

[0030] Figure 14 is a side view of a two-channel photoion detection system for a TOF mass analyzer according to various embodiments.

[0031] Figure 15 is an exemplary flowchart according to various embodiments, showing a method for maintaining the resolution of a TOF mass analyzer despite a loss of resolution in one or more channels of a multi-channel ion detection system of the TOF mass analyzer.

[0032] Figure 16 is a schematic diagram of a system according to various embodiments including one or more different software modules that perform a method for maintaining the resolution of a TOF mass analyzer despite a loss of resolution in one or more channels of a multi-channel ion detection system of the TOF mass analyzer.

[0033] Before detailing one or more embodiments of the present teachings, those skilled in the art will understand that the present teachings in their application are not limited to the details of the construction, the arrangement of components, and the arrangement of steps set forth in the following detailed description or illustrated in the drawings. Moreover, it is to be understood that the language and terminology used herein are for the purpose of description and should not be regarded as limiting. Detailed Description

[0034] Computer-implemented system

[0035] Figure 1FIG. 0 is a block diagram illustrating a computer system 100 on which embodiments of the present teachings may be implemented. The computer system 100 includes a bus 102 or other communication mechanism for transferring information, and a processor 104 coupled to the bus 102 for processing information. The computer system 100 also includes a memory 106, which may be a random access memory (RAM) or other dynamic storage device, coupled to the bus 102 for storing instructions to be executed by the processor 104. The memory 106 may also be used to store temporary variables or other intermediate information during execution of instructions to be executed by the processor 104. The computer system 100 also includes a read only memory (ROM) 108 or other static storage device coupled to the bus 102 for storing instructions and static information for the processor 104. A storage device 110, such as a magnetic disk or optical disk, is provided and coupled to the bus 102 for storing information and instructions.

[0036] The computer system 100 may be coupled via the bus 102 to a display 112, such as a cathode ray tube (CRT) or liquid crystal display (LCD), for displaying information to a computer user. An input device 114 including alphanumeric keys and other keys is coupled to the bus 102 for transferring information and command selections to the processor 104. Another type of user input device is a cursor control 116, such as a mouse, trackball, or cursor direction keys, for transferring direction information and command selections to the processor 104 and for controlling cursor movement on the display 112. This input device typically has two degrees of freedom in two axes, namely the first axis (i.e., x) and the second axis (i.e., y), which allows the device to specify a position in a plane.

[0037] The computer system 100 can execute the present teachings. Consistent with certain implementations of the present teachings, results are provided by the computer system 100 in response to execution of one or more sequences of one or more instructions contained in the memory 106. Such instructions may be read into the memory 106 from another computer readable medium, such as the storage device 110. Execution of the sequences of instructions contained in the memory 106 causes the processor 104 to perform the processes described herein. Alternatively, hardwired circuitry may be used in place of or in combination with software instructions to implement the present teachings. Accordingly, implementations of the present teachings are not limited to any specific combination of hardware circuitry and software.

[0038] In various embodiments, computer system 100 can be connected across a network to one or more other computer systems, such as computer system 100, to form a networked system. The network can include a private network or a public network such as the Internet. In a networked system, one or more computer systems can store data and provide the data to other computer systems. In a cloud computing scenario, the one or more computer systems that store and provide the data can be referred to as servers or the cloud. For example, the one or more computer systems can include one or more web servers. For example, other computer systems that send data to and receive data from the server or the cloud can be referred to as clients or cloud devices.

[0039] As used herein, the term "computer-readable medium" refers to any medium that participates in providing instructions to processor 104 for execution. Such a medium can take many forms, including but not limited to non-volatile media, volatile media, and transmission media. Non-volatile media includes, for example, optical or magnetic disks, such as storage device 110. Volatile media includes dynamic memory, such as memory 106. Transmission media includes coaxial cables, copper wire, and fiber optics, including the wires that make up bus 102.

[0040] The general form of a computer-readable medium or computer program product includes, for example, a floppy disk, flexible disk, hard disk, magnetic tape, or any other magnetic medium, a CD-ROM, a digital video disk (DVD), a Blu-ray disk, any other optical medium, a thumb drive, a memory card, RAM, PROM, and EPROM, FLASH-EPROM, any other memory chip or cartridge tape, or any other tangible medium from which a computer can read.

[0041] Various forms of computer-readable media may be involved in carrying one or more sequences of one or more instructions to processor 104 for execution. For example, the instructions can initially be carried on a magnetic disk of a remote computer. The remote computer can load the instructions into its dynamic memory and send the instructions over a telephone line using a modem. A modem local to computer system 100 can receive the data on the telephone line and convert the data into an infrared signal using an infrared transmitter. An infrared detector coupled to bus 102 can receive the data carried in the infrared signal and place the data on bus 102. Bus 102 carries the data to memory 106, and processor 104 retrieves and executes the instructions from memory 106. The instructions received by memory 106 can optionally be stored on storage device 110 before or after being executed by processor 104.

[0042] According to various embodiments, instructions configured to be executed by a processor to implement a method are stored on a computer-readable medium. The computer-readable medium can be a device that stores digital information. For example, the computer-readable medium includes a compact disc read-only memory (CD-ROM) for storing software as known in the art. The computer-readable medium is accessed by a processor adapted to execute the instructions configured to be executed.

[0043] For purposes of illustration and description, the following description of various implementations of the present teachings has been presented. It is not exhaustive and does not limit the present teachings to the precise forms disclosed. Modifications and variations are possible in light of the above teachings, or may be obtained from practice of the present teachings. Additionally, the described implementations include software, but the present teachings can be implemented as a combination of hardware and software or in hardware alone. Both object-oriented and non-object-oriented programming systems can implement the present teachings.

[0044] Using fewer channels for qualitative analysis

[0045] As described above, some conventional time-of-flight (TOF) mass analyzers use an ion detection system including a four-channel digitizer. For example, the four-channel digitizer can include a time-to-digital converter (TDC) or an analog-to-digital converter (ADC). The multi-channel ion detection system provides two main advantages: improved resolution through independent calibration of the channels (also known as channel alignment) and enhanced dynamic range.

[0046] The resolution on a TOF mass analyzer is a key driver of instrument performance. Unfortunately, over time, the resolution of a TOF mass analyzer can degrade until it is no longer acceptable to the customer.

[0047] For a multi-channel TOF mass analyzer, the resolution of some channels can degrade faster and more than that of other channels. For example, in a four-channel TOF mass analyzer, the resolution measured by the two channels receiving data from the two outermost electrodes typically degrades faster than that measured by the two channels receiving data from the two innermost electrodes.

[0048] First, simply discarding data from any channel with degraded resolution might seem like a solution to this problem. However, discarding the signal from even a single channel can reduce the overall sensitivity of the TOF mass analyzer and defeat the original purpose of using a multi-channel ion detection system.

[0049] As a result, additional systems and methods are needed to address the problem of degraded resolution in some channels of the multi-channel ion detection system of a TOF mass analyzer.

[0050] One of ordinary skill in the art can understand that the terms "mass analyzer" and "mass spectrometer" can be used interchangeably. Generally, a mass analyzer refers to a device at one or more stages of a mass spectrometer. In other words, a mass analyzer is usually just a component of a mass spectrometer. However, in industrial practice, the entire mass spectrometer is often referred to in terms of its mass analyzer. For example, a mass spectrometer including a TOF mass analyzer is often called a TOF mass spectrometer, even though the TOF mass analyzer is just one component.

[0051] Resolution and channel alignment

[0052] One advantage of a multi-channel ion detection system is improved resolution through independent calibration of channels referred to as channel alignment. Channel alignment is needed because when ion packets strike the detector, these ion packets are shaped in a non-ideal manner.

[0053] Figure 2 FIG. 200 is a side view of a TOF ion detection system, showing exemplary ion packets. Just before they strike the microchannel plate (MCP) of the TOF ion detection system, the exemplary ion packets each have an ideal shape and an ideal orientation. An MCP is a device that converts ion impacts on one side of the MCP into electron emission on the corresponding other side of the MCP. Generally, an MCP generates many electrons for each ion impact. As a result, the MCP acts as a multiplier or amplifier for ion impacts. Due to this amplification effect, multiple MCPs can also be used in series to increase the amplification factor of ion impacts.

[0054] The shapes of ion packets 201 and 202 are ideal with respect to Figure 2 the MCP 210 because these shapes are substantially the same flat shape as the MCP 210. In other words, due to this shape, all the ions of ion packet 201 will hit the MCP210 simultaneously, and all the ions of ion packet 202 will also hit the MCP 210 simultaneously.

[0055] The orientations of ion packets 201 and 202 are ideal with respect to the MCP 210 because these orientations are substantially parallel to the MCP210. Similarly, this orientation allows all the ions of ion packet 201 to hit the MCP 210 simultaneously, and all the ions of ion packet 202 to hit the MCP 210 simultaneously.

[0056] The shape and orientation of ion packets are important because they affect the resolution of the TOF ion detection system. Similarly, in a TOF ion detection system, resolution basically refers to how well the distance between ion packets can be measured. In other words, the highest resolution will be the minimum distance between two different ion packets that can still resolve the two ion packets.

[0057] Figure 2The ideal shapes and ideal orientations of the ion packets 201 and 202 in [description] allow for very high resolution. Ion packets with such shapes and orientations can be resolved even when placed much closer together than the ion packets 201 and 202. However, the minimum distance between two ion packets that can still be resolved by two different ion packets increases, and ion packets with non-ideal shapes and non-ideal orientations can reduce the resolution.

[0058] Figure 3 is a side view 300 of a TOF ion detection system, showing exemplary ion packets, just before they impinge on the MCP of the TOF ion detection system, each exemplary ion packet having an ideal shape and a non-ideal orientation. In Figure 3 the ion packets 301 and 302 are oriented or tilted at an angle with respect to the MCP 210. This tilting of the ion packets 301 and 302 within the ion beam results in a reduction in resolution.

[0059] By determining whether the ion packets 301 and 302 can be placed closer together and still be distinguishable at the MCP 210, this reduction in resolution can be seen. If the ion packet 301 is placed closer to the ion packet 302, the leading edge of the ion packet 301 immediately begins to overlap with the trailing edge of the ion packet 302. If these edges overlap, the ion packets cannot be distinguished at the MCP 210. This means that the ion packets 301 and 302 cannot be placed closer together. Therefore, Figure 2 and Figure 3 the comparison with [reference] shows how a non-ideal orientation can reduce the resolution.

[0060] In practice, TOF mass analyzers typically produce ion packets with a tilted orientation or a non-ideal orientation. However, fortunately, there are traditional remedies for this problem. To compensate for the tilted packets, the MCP can be tilted accordingly in a calibration step to address ion packets with a tilted orientation or a non-ideal orientation. A non-ideal ion packet shape can also reduce the resolution.

[0061] Figure 4 is a side view 400 of a TOF ion detection system, showing exemplary ion packets, just before they impinge on the MCP of the TOF ion detection system, each exemplary ion packet having a non-ideal shape and an ideal orientation. In Figure 4 the ion packets 401 and 402 have an arcuate sausage or bulging shape with respect to the MCP 210. For example, the length 411 of the ion packet 401 is about 40 mm, and the depth of the bulge 412 of the ion packet 401 is much less than 1 mm. The bulging shape of the ion packets 401 and 402 in a TOF mass analyzer is common.

[0062] This bulging shape reduces the resolution of the ion detection system. LikeFigure 3 ion packets 301 and 302, if Figure 4 ion packets 401 and 402 are closer than Figure 4 shown in, they cannot be resolved at the MCP 210 Figure 4 ion packets 401 and 402. This is because, for example, if ion packets 401 and 402 are placed slightly closer together, the two trailing edges of ion packet 402 will overlap the leading edge of ion packet 401. Like ion packets, the MCP can also have a non-ideal shape. In practice, the MCP often has a convex shape.

[0063] Four-channel digitizer

[0064] Conventional TOF ion detection systems have compensated for the loss of resolution caused by the convex shape of the ion packets and the convex shape of the MCP by using four electrodes and a four-channel digitizer.

[0065] Figure 5 is a side view 500 of a TOF ion detection system, showing how four electrodes and a four-channel digitizer are used to obtain digitized signals of exemplary ion packets each having a non-ideal shape to improve resolution. In Figure 5 it, two MCPs 510 positioned in series are struck by ion packets 301 and 302 having a convex shape. The multiplied electrons generated by the MCP 510 are collected by four segmented anode electrode plates 521, 522, 523, and 524. Each of the anode electrode plates 521, 522, 523, and 524 is electrically connected to a separate channel of a four-channel digitizer 530.

[0066] The four-channel digitizer 530 is, for example, an ADC or a TDC. For example, each of the anode electrode plates 521, 522, 523, and 524 can also be electrically connected to the four-channel digitizer 530 through a four-channel preamplifier (not shown). The four-channel preamplifier amplifies the electrical signals received from the electrode plates.

[0067] The MCP 510 essentially converts the ion impact image on one side into a corresponding electron emission image on the other side. Although the ion packets 301 and 302 have a convex shape, their images on either side of the MCP 510 have a rectangular pattern or shape.

[0068] Figure 6 is Figure 5 front view 600 of the impact side of the MCP of Figure 6 in which Figure 5 side 511 of the MCP 510 of Figure 5 ion packets 301 and 302 ofFigure 5 The ion packets 301 and 302 have a convex shape, so the ions of each packet first strike Figure 6 the center or an inner part of the rectangular pattern 305 of Figure 5 . After that, the ions of each packet strike two outer edges of the rectangular pattern 305. Generally, the rectangular pattern 305 has a width 307 of about 10 mm and a length 309 of about 40 mm. Electrons are emitted from

[0069] Figure 7 is Figure 5 a front view 700 of four electrodes of Figure 7 . For example,

[0070] shows how the four segmented anode electrode plates 521, 522, 523, and 524 are positioned to detect ions from a circular MCP. The MCP that uses the corresponding rectangular pattern 305 that generates electrons emits the electrons onto the electrodes 521, 522, 523, and 524.

[0071] Return Figure 5 , the four channels 531, 532, 533, and 534 of the four-channel digitizer 530 are calibrated to combine or align the measurements from different channels at different times to address the longitudinal convexity of the ion packets.

[0072] Figure 8 is an exemplary series of time plots 800, showing how to align or combine the measurements from the four channels of the four-channel digitizer in Figure 5 to compensate for the non-ideal shape of the ion packets and improve the overall resolution of the ion detection system. Each time plot is a graph of the electron flux intensity versus time.

[0073] In Figure 8 , the time plot 851 shows respectively the intensities 812 and 811 of the ion packets 302 and 301 measured in the channel 531 of the four-channel digitizer 530 in Figure 5 . Figure 5 The time plot 852 in Figure 8 shows respectively the intensities 822 and 821 of the ion packets 302 and 301 measured in the channel 532 of the four-channel digitizer 530 in Figure 5 . Figure 5 The time plot 853 in Figure 8The timing diagrams 853 respectively show the Figure 5 intensities 832 and 831 of ion packets 302 and 301 measured in channel 533 of the four-channel digitizer 530 of Figure 5 . Finally, Figure 8 the timing diagrams 854 respectively show the Figure 5 intensities 842 and 841 of ion packets 302 and 301 measured in channel 534 of the four-channel digitizer 530 of Figure 5 .

[0074] In Figure 8 the timing diagram 860, the intensities measured in timing diagrams 851, 852, 853 and 854 are combined. For example, these values are summed in the timing diagram 860. This results in Figure 5 two intensity peaks for each of the ion packets 302 and 301 of Figure 5 , one being a combination of the measurements from the two inner electrode plates 522 and 523 of Figure 5 , while one being a combination of the measurements from the two outer electrode plates 521 and 524 of Figure 8 . For example, in Figure 5 the timing diagram 860, peaks 861 and 862 are the two intensity peaks measured from the ion packet 302 of Figure 5 , while peaks 863 and 864 are the two intensity peaks measured from the ion packet 301 of

[0075] Note that in Figure 5 , due to the convex shape of the ion packet, the time difference between the detection of the central or inner ions of the ion packet at electrodes 522 and 523 and the detection of the outer ions of the ion packet at electrodes 521 and 524 is Δt501. In Figure 8 , this Δt 501 is the difference between the centers of peaks 861 and 862, while Δt 502 is the difference between the centers of peaks 863 and 864. This time difference Δt 501 or Δt 502 resulting from the convex shape of the ion packet reduces the detection resolution. It reduces the detection resolution by reducing the space between the intensities that can be measured for two different packets. In other words, as shown in the timing diagram 860, because of the convex shape of the ion packet, the intensity of a single ion packet spreads over time, thus reducing the resolution.

[0076] However, since multiple channels are used to measure different parts of the convex shape of the ion packet, it is possible to compensate for the spreading of the intensity. This is shown in the timing diagram 870. Basically, in Figure 8 the timing diagram 870 of Figure 5 , peaks 861 and 862 of the ion packet 302 of Figure 5The peaks 863 and 864 of the ion packet 302 are combined into peak 872. In other words, Figure 5 The digitizer 530 is calibrated to align the intensities of channels 531 and 534 with the intensities of channels 532 and 533. For example, the calibration equation m = a×(t - t 0 ) 2 is used for this calibration, where m is the mass, a is the slope, t is the time, and t 0 is the time offset. Once calibrated, the intensities of all four channels are combined.

[0077] Figure 8 The time plot 870 shows that the resolution has been restored. In other words, the spacing between the peaks (871 and 872) of different packets has increased. If Figure 5 the ion packets overlap, this can be shown more clearly.

[0078] Figure 9 is a side view 900 of the same TOF ion detection system as shown in Figure 5 , where exemplary ion packets overlap. In Figure 9 , the front of ion packet 901 overlaps with the trailing edge of ion packet 902. If only one electrode and one digitizing channel are used, ion packets 901 and 902 cannot be distinguished. However, by using separate electrodes and a four-channel digitizer, packets 901 and 902 can be distinguished.

[0079] Figure 10 is an exemplary series of time plots 1000 showing how to align or combine the measurements from the four channels of the four-channel digitizer in Figure 9 to compensate for the non-ideal shape of the ion packets and improve the overall resolution of the ion detection system, even when the ion packets overlap. In Figure 10 , time plot 1051 shows the intensities 1012 and 1011 of ion packets 902 and 901 measured in channel 531 of the four-channel digitizer 530 in Figure 9 . Figure 9 The time plot 1052 in Figure 10 shows the intensities 1022 and 1021 of ion packets 902 and 901 measured in channel 532 of the four-channel digitizer 530 in Figure 9 . Figure 9 The time plot 1053 in Figure 10 shows the intensities 1032 and 1031 of ion packets 902 and 901 measured in channel 533 of the four-channel digitizer 530 in Figure 9 . Finally, Figure 9 the time plot 1054 in Figure 10 shows the intensities of ion packets 902 and 901 measured in channel 534 of the four-channel digitizer 530 in Figure 9Measured in channel 534 of the four-channel digitizer 530 Figure 9 The intensities 1042 and 1041 of ion packets 902 and 901.

[0080] At Figure 10 In the time graph 1060, the intensities measured in time graphs 1051, 1052, 1053, and 1054 are combined. This results in Figure 9 Two intensity peaks for each of the ion packets 902 and 901, one being the combination of the measurements from Figure 9 The two inner electrode plates 522 and 523, while one is the combination of the measurements from Figure 9 The two outer electrode plates 521 and 524. For example, in Figure 10 In the time graph 1060, peaks 1061 and 1062 are the two intensity peaks measured from Figure 9 The ion packet 902, while peaks 1063 and 1064 are the two intensity peaks measured from Figure 9 The ion packet 901.

[0081] Note that in Figure 10 , Figure 9 Peak 1062 of the ion packet 902 in Figure 9 Overlaps with peak 1063 of the ion packet 901 in Figure 9 This shows that the overlap caused by the convex shape of the ion packets in

[0082] However, since multiple channels are used to measure different parts of the convex shape of the ion packets, it is possible to compensate for this overlap. This is shown in the time graph 1070. Basically, in Figure 10 In the time graph 1070 of Figure 9 Peaks 1061 and 1062 of the ion packet 902 in Figure 9 Are combined into peak 1071, while

[0083] The low resolution of some channels reduces the overall resolution

[0084] As mentioned above, for a multi-channel TOF mass analyzer, the resolution of some channels can be reduced faster and more than that of other channels. For example, in a four-channel TOF mass analyzer, the resolution measured by the two channels receiving data from the two outermost electrodes is usually reduced faster than that measured by the two channels receiving data from the two innermost electrodes. Return Figure 7, for example, the resolution measured by two channels receiving data from the two outermost electrodes 521 and 524 generally decreases faster than the resolution measured by two channels receiving data from the two innermost electrodes 522 and 523.

[0085] Figure 11 is an exemplary series of timing diagrams 1100 according to various embodiments, showing how the measurements from four channels of a four-channel digitizer can vary in resolution. In Figure 5 , timing diagram 1151 shows, respectively, the Figure 11 intensities 1112 and 1111 of ion packets 302 and 301 measured in channel 531 of the four-channel digitizer 530 in Figure 5 . Figure 5 Timing diagram 1152 in Figure 11 shows, respectively, the Figure 5 intensities 1122 and 1121 of ion packets 302 and 301 measured in channel 532 of the four-channel digitizer 530 in Figure 5 . Figure 11 Timing diagram 1153 in Figure 5 shows, respectively, the Figure 5 intensities 1132 and 1131 of ion packets 302 and 301 measured in channel 533 of the four-channel digitizer 530 in Figure 11 . Finally, Figure 5 timing diagram 1154 in Figure 5 shows, respectively, the

[0086] intensities 1142 and 1141 of ion packets 302 and 301 measured in channel 534 of the four-channel digitizer 530 in Figure 11 . In Figure 5 , timing diagrams 1151 and 1154 show intensities with reduced resolution compared to timing diagrams 1152 and 1153. These reduced resolutions reflect the reduced resolution typically found for

[0087] the two outermost electrodes 521 and 524. Figure 11 Furthermore, in timing diagram 1160 in Figure 5 , the intensities measured in timing diagrams 1151, 1152, 1153, and 1154 are combined. For example, these values are summed in FIG. 1160. This results in Figure 5 two intensity peaks for each of the ion packets 302 and 301, one being a combination of the measurements from Figure 5 the two inner electrode plates 522 and 523, while one is a combination of the measurements from Figure 11 the two outer electrode plates 521 and 524. For example, in timing diagram 1160 in Figure 5Two intensity peaks measured from the ion packet 302, while peaks 1163 and 1164 are two intensity peaks measured from Figure 5 the ion packet 301.

[0088] Note that in Figure 5 , due to the convex shape of the ion packet, the time difference between the detection of the central or internal ions of the ion packet at electrodes 522 and 523 and the detection of the external ions of the ion packet at electrodes 521 and 524 is Δt501. In Figure 11 , this Δt 501 is the difference between the centers of peaks 1161 and 1162, while Δt 502 is the difference between the centers of peaks 1163 and 1164. This time difference Δt 501 or Δt 502 generated by the convex shape of the ion packet reduces the detection resolution. It reduces the detection resolution by reducing the space between the intensities that can be measured for two different packets. In other words, as shown in the time plot 1160, because due to the convex shape of the ion packet, the intensity of a single ion packet unfolds over time, the resolution is reduced.

[0089] However, since multiple channels are used to measure different parts of the convex shape of the ion packet, it is possible to compensate for the unfolding of the intensity. This is shown in the time plot 1170. Basically, in Figure 11 the time plot 1170 of Figure 5 , the peaks 1161 and 1162 of the ion packet 302 of Figure 5 are combined into peak 1171, while Figure 5 , the digitizer 530 of 0 is calibrated to align the intensities of channels 531 and 534 with the intensities of channels 532 and 533. For example, the calibration equation m = a×(t - t 2 ) 0 is used for calibration, where m is the mass, a is the slope, t is the time, and t

[0090] Figure 11 The time plot 1170 of Figure 11 shows that some resolution has been restored. In other words, the spacing between the peaks (1171 and 1172) of different packets has increased. However, compared to the resolution found in the time plots 1152 and 1154, this resolution is still reduced. In other words,

[0091] Only using the highest resolution channels for qualitative analysis

[0092] In various embodiments, the problem of reduced overall resolution due to reduced resolution in some channels of a multi-channel ion detection system of a TOF mass analyzer is addressed by separately using the signal intensity detected in the highest resolution channel for qualitative analysis and using the signal intensities of the highest resolution channel and the lower resolution channels for quantitative analysis. Return Figure 5 , for example, using the digital values of channels 532 and 533 of digitizer 530 to obtain the signal intensity and resolution for qualitative analysis. However, for quantitative analysis (intensity only), in addition to the digital values of channels 532 and 533, the digital values of channels 531 and 534 of digitizer 530 are also used.

[0093] In various embodiments, for quantitative analysis at each interval (m / z), if there are also signals in channels 532 and 533 in this same interval (m / z), one approach is to include only the intensities from channels 531 and 534. This approach ignores a small portion of the signal from the broader, poorly resolved portions of channels 531 and 534, but still captures most of the signal and retains the resolution from channels 532 and 533.

[0094] Figure 12 is an exemplary series of time plots 1200 according to various embodiments, showing how the measurements from the four channels of a four-channel digitizer can be separately combined for qualitative and quantitative analysis when the measurements from the four channels vary in resolution. Again, in Figure 5 , the time plot 1251 shows the intensities 1212 and 1211 of ion packets 302 and 301 measured in channel 531 of the four-channel digitizer 530 in Figure 12 . Figure 5 The time plot 1252 in Figure 5 shows the intensities 1222 and 1221 of ion packets 302 and 301 measured in channel 532 of the four-channel digitizer 530 in Figure 12 . Figure 5 The time plot 1253 in Figure 5 shows the intensities 1232 and 1231 of ion packets 302 and 301 measured in channel 533 of the four-channel digitizer 530 in

[0095] Figure 12 . Finally, the time plot 1254 in Figure 5 shows the intensities 1242 and 1241 of ion packets 302 and 301 measured in channel 534 of the four-channel digitizer 530 in Figure 5 . Figure 12 The time plot 1254 in Figure 5 shows the intensities 1242 and 1241 of ion packets 302 and 301 measured in channel 534 of the four-channel digitizer 530 in Figure 5 .

[0096] Furthermore, in Figure 12 compared with time graphs 1252 and 1253, time graphs 1251 and 1254 show intensities with reduced resolution. These reduced resolutions reflect the reduced resolutions typically found for Figure 5 the two outermost electrodes 521 and 524.

[0097] Therefore, for qualitative analysis, only the intensities 1222 and 1221 of time graph 1252 and the intensities 1232 and 1231 of time graph 1253 are combined in time graph 1260, thereby generating intensities 1262 and 1264. Time graph 1260 shows that the higher resolution of time graphs 1252 and 1253 is retained using this combination.

[0098] For quantitative analysis, the intensities 1212 and 1211 of time graph 1251 and the intensities 1241 and 1242 of time graph 1254 are combined into the intensities 1261 and 1263 of time graph 1270. However, only portions of intensities 1261 and 1263 are used for quantitative analysis. For example, intensities 1262 and 1264 are aligned with intensities 1261 and 1263. Only those portions of intensities 1261 and 1263 that overlap with the time interval or m / z interval having intensities 1262 and 1264 are used for quantitative analysis.

[0099] Those skilled in the art understand that an interval is a range of time or m / z values used to combine intensities. Time graph 1270 depicts interval 1271. Interval 1271 shows that intensity 1261 overlaps intensity 1262 in four intervals, and intensity 1263 overlaps intensity 1264 in four intervals. Then the intensities of the four intervals of intensity 1261 and the intensities of the four intervals of intensity 1263 are combined with intensities 1262 and 1264 for quantitative analysis.

[0100] In various embodiments, peak finding is performed for each channel. Figure 5 Channels 532 and 533 of

[0101] are used to construct an optimal resolution peak shape model. However, the summed signal intensity from all channels is used for each peak. This requires more processing power but captures all measured signals.

[0102] Multi-channel ion detection system

[0103] Figure 13 Exemplary FIG. 1300 of a multi-channel ion detection system for a TOF mass analyzer according to various embodiments, which maintains the resolution of the TOF mass analyzer despite a loss of resolution in one or more channels. Figure 13 The system includes a multi-channel detector and electron multiplier 1305, a multi-channel digitizer 1330, and a processor 1340.

[0104] The multi-channel detector and electron multiplier 1305 are struck by an ion packet 1301 of a TOF mass analyzer (not shown). The ion packet 1301 strikes a first side of the multi-channel detector and electron multiplier 1305. The multi-channel detector and electron multiplier 1305 convert the strikes into multiplied electrons and emit the multiplied electrons from two or more segmented electrodes 1320 on a second side of the multi-channel detector and electron multiplier 1305. Each of the two or more segmented electrodes 1320 corresponds to strikes in different regions across the length of the first side and emits electrons based on those strikes.

[0105] The multi-channel digitizer 1330 can be, but is not limited to, a multi-channel ADC or a multi-channel TDC. The multi-channel digitizer 1330 is electrically connected to the two or more segmented electrodes 1320. For each ion packet in the ion packet 1301, the multi-channel digitizer 1330 converts the electrons received from each of the two or more segmented electrodes 1320 into digital values in the channels of the multi-channel digitizer 1330. For example, the multi-channel digitizer 1330 is a four-channel device, as Figure 13 shown.

[0106] The processor 1340 can be a separate device as Figure 13 shown or can be a processor or controller used by a mass spectrometer. The processor 1340 can be, but is not limited to, a controller, a computer, a microprocessor, Figure 1 a computer system of, or any device capable of sending and receiving control signals and data and capable of analyzing data.

[0107] The processor 1340 receives digital values from at least two or more channels of the multi-channel digitizer 1330. The processor 1340 uses digital values of a predetermined subset of one or more channels of the at least two or more channels to calculate qualitative information about the ion packet. It is known that the predetermined subset of the one or more channels provides the highest resolution of the at least two or more channels. Qualitative information includes, but is not limited to, m / z peak shape.

[0108] For example, Figure 5At least two or more of the channels are channels 531, 532, 533, and 534. A predetermined subset of one or more channels includes the innermost channels 532 and 533, which provide the highest resolution of channels 531, 532, 533, and 534. Alternatively, for example, Figure 5 At least two or more of the channels are channels 531, 532, and 533. A predetermined subset of one or more channels still includes the innermost channels 532 and 533, which provide the highest resolution of channels 531, 532, and 533. For example, in this second case, channel 534 is not used.

[0109] Return Figure 13 , in various embodiments, the processor 1340 also uses digital values of at least two or more channels to calculate quantitative information about the ion packet. The quantitative information includes, but is not limited to, m / z peak intensity or area.

[0110] In various embodiments, the multi-channel detector and electron multiplier 1305 can be, for example, an electrical system or an optoelectronic system. As Figure 13 shown, the multi-channel detector and electron multiplier 1305 is an electrical system including one or more microchannel plates 1310 and a plurality of segmented anode electrode plates 1320.

[0111] A series of one or more microchannel plates 1310 is impacted by an ion packet 1301 of a TOF mass analyzer (not shown). The ion packet 1301 impacts the series of one or more microchannel plates 1310 on a first side of the series of one or more microchannel plates 1310. The series of one or more microchannel plates 1310 converts the impact into multiplied electrons emitted from a second side of the series of one or more microchannel plates 1310.

[0112] The plurality of segmented anode electrode plates 1320 receive the emitted electrons from the series of one or more microchannel plates 1310. The plurality of segmented anode electrode plates 1320 are arranged in a plane parallel to the series of one or more microchannel plates 1310 and are located behind the series of one or more microchannel plates 1310.

[0113] For example, the multi-channel detector and electron multiplier 1305 can also be an optoelectronic system.

[0114] Figure 14 is a side view 1400 of an optoelectronic dual-channel ion detection system for a TOF mass analyzer according to various embodiments. The optoelectronic dual-channel ion detection system includes a series of one or more microchannel plates 1410, a scintillator 1420, two or more segmented light tubes 1431, 1432, 1433, and 1434, a first photomultiplier tube (PMT) 1441, a second PMT 1442, and a dual-channel digitizer 1450.

[0115] In various embodiments, the dual-channel digitizer 1450 is a dual-channel analog-to-digital converter (ADC). In various embodiments, the dual-channel digitizer 1450 is a dual-channel time-to-digital converter (TDC).

[0116] The first microchannel plate in a series of one or more microchannel plates 1410 is struck by an ion packet 1401 in a rectangular pattern on a first side 1411 of the series of one or more microchannel plates 1410. The series of one or more microchannel plates 1410 converts the strike into multiplied electrons emitted in a rectangular pattern on a second side 1412 of the series of one or more microchannel plates 1410. The longer side of the rectangular pattern is the length, and the shorter side of the rectangular pattern is the width. Due to the raised shape of the ion packet 1401, for example, the ions of each packet strike the central inner region of the rectangular pattern before striking two outer regions at each end of the rectangular pattern.

[0117] The scintillator 1420 is located parallel to and after the series of one or more microchannel plates 1410. The scintillator 1420 receives electrons emitted in a rectangular pattern from the second side 1412 of the series of one or more microchannel plates 1410 on a first side 1421 of the scintillator 1420. The scintillator 1420 converts the electrons into photons emitted in a rectangular pattern on a second side 1422 of the scintillator 1420.

[0118] Two or more segmented light pipes 1431, 1432, 1433, and 1434 are connected to the second side 1422 of the scintillator 1420 to receive photons from the second side 1422 of the scintillator 1420. The two or more segmented light pipes 1431, 1432, 1433, and 1434 together have a large enough area to receive photons from the rectangular pattern. The two or more light pipes 1431, 1432, 1433, and 1434 include one or more inner light pipes 1432 and 1433 positioned to receive photons from the central inner region of the rectangular pattern. The two or more light pipes 1431, 1432, 1433, and 1434 include one or more outer light pipes 1431 and 1434 positioned to receive photons from the two outer regions at each end of the rectangular pattern.

[0119] The first photomultiplier tube 1441 is connected to one or more inner light pipes 1432 and 1433 and converts the photons received by the one or more inner light pipes 1432 and 1433 into first multiplied electrons for each packet. The second photomultiplier tube 1442 is connected to one or more outer light pipes 1431 and 1434 and converts the photons received by the one or more outer light pipes 1431 and 1434 into second multiplied electrons for each packet.

[0120] The dual-channel digitizer 1450 includes a first channel 1451 electrically connected to a first photomultiplier tube 1441, which converts the first multiplied electrons into a first digital value for each ion packet. The dual-channel digitizer 1450 includes a second channel 1452 electrically connected to a second photomultiplier tube 1442, which converts the second multiplied electrons into a second digital value for each ion packet.

[0121] The first channel 1451 and the second channel 1452 are independently calibrated to align the first digital value and the second digital value in time and to resolve the bump shape of the ion impact for each ion packet.

[0122] Return Figure 13 , in various embodiments, the processor 1340 calculates quantitative information about the ion packet by using the intensity of a predetermined subset of the digital values and by using the intensity of the digital values in only each m / z or time interval of the remaining channels of at least two or more channels that also includes the intensity of the predetermined subset of the digital values.

[0123] In various embodiments, the processor 1340 calculates quantitative information about the ion packet by performing m / z peak finding on the digital values of each of at least two or more channels after receiving all the ion packets 1301, using the intensity of a predetermined subset of the digital values to construct the best resolution m / z peak shape, and using the intensity of the digital values of at least two or more channels to calculate the total intensity of each m / z peak.

[0124] In various embodiments, a predetermined subset of one or more channels known to provide the highest resolution among at least two or more channels is determined during the auto-tune resolution process of the TOF mass analyzer. For example, the auto-tune resolution process of the TOF mass analyzer is typically run by the customer once a week or once a month.

[0125] In various embodiments, the predetermined subset includes one channel.

[0126] In various embodiments, for a four-channel digitizer, as Figure 13 shown, the predetermined subset includes two channels.

[0127] In various embodiments, the multi-channel digitizer 1330 is electrically connected to a plurality of segmented anode electrode plates to provide channels for each plate.

[0128] In various embodiments, the multi-channel digitizer 1330 is electrically connected to a plurality of segmented anode electrode plates to provide channels for two or more plates. For example, U.S. Provisional Application No. 62 / 470,486 describes a multi-channel ion detection system in which the multi-channel digitizer provides channels for two segmented anode electrode plates.

[0129] Multi-channel ion detection method

[0130] Figure 15 FIG. 1500 is an exemplary flowchart according to various embodiments, showing a method for maintaining the resolution of a TOF mass analyzer, despite a loss of resolution in one or more channels of a multi-channel ion detection system of the TOF mass analyzer.

[0131] In step 1510 of method 1500, an ion packet of a TOF mass analyzer is converted into multiplied electrons upon impact on a first side of a multi-channel detector and an electron multiplier using the multi-channel detector and the electron multiplier, and the multiplied electrons are emitted from two or more segmented electrodes on a second side of the multi-channel detector and the electron multiplier. Each of the two or more segmented electrodes corresponds to impacts in different regions across the length of the first side and emits electrons based on these impacts.

[0132] In step 1520, a multi-channel digitizer converts the electrons received by each of the two or more segmented electrodes for each ion packet in the ion packet into digital values in channels of the multi-channel digitizer.

[0133] In step 1530, a processor receives digital values from at least two or more channels of the multi-channel digitizer, and calculates qualitative information about the ion packet using digital values of a predetermined subset of one or more channels known to provide the highest resolution of the at least two or more channels.

[0134] Multi-channel ion detection computer program product

[0135] In various embodiments, a computer program product includes a tangible computer-readable storage medium having content including a program with instructions that, when executed on a processor, perform a method for maintaining the resolution of a TOF mass analyzer, despite a loss of resolution in one or more channels of a multi-channel ion detection system of the TOF mass analyzer. Such a method is performed by a system including one or more different software modules.

[0136] Figure 16 FIG. 1600 is a schematic diagram of a system 1600 including one or more different software modules according to various embodiments, the one or more different software modules performing a method for maintaining the resolution of a TOF mass analyzer, despite a loss of resolution in one or more channels of a multi-channel ion detection system of the TOF mass analyzer. System 1600 includes a measurement module 1610 and an analysis module 1620.

[0137] Measurement module 1610 instructs the multi-channel detector and the electron multiplier to convert the impact of the ion packet of the TOF mass analyzer on the first side of the multi-channel detector and the electron multiplier into multiplied electrons, and emit the multiplied electrons from two or more segmented electrodes on the second side of the multi-channel detector and the electron multiplier. Each of the two or more segmented electrodes corresponds to impacts in different regions across the length of the first side and emits electrons based on these impacts.

[0138] Measurement module 1610 instructs the multi-channel digitizer to convert the electrons received by each of the two or more segmented electrodes for each ion packet in the ion packet into digital values in the channels of the multi-channel digitizer.

[0139] Analysis module 1620 receives digital values from at least two or more channels of the multi-channel digitizer. Analysis module 1620 uses the digital values of a predetermined subset of one or more channels known to provide the highest resolution of the two or more channels among the at least two or more channels to calculate qualitative information about the ion packet.

[0140] Although the present teachings are described in conjunction with various embodiments, it is not intended to limit the present teachings to these embodiments. On the contrary, as will be understood by those skilled in the art, the present teachings cover various alternatives, modifications, and equivalents.

[0141] In addition, when describing various embodiments, the specification may have presented the method and / or process as steps in a particular order. However, insofar as the method or process does not depend on the particular order of steps set forth herein, the method or process should not be limited to the particular order of steps described. Those of ordinary skill in the art will understand that other orders of steps are possible. Therefore, the particular order of steps set forth in the specification should not be construed as a limitation on the claims. In addition, the claims reciting the method and / or process should not be limited to performing their steps in the order written, and those skilled in the art can readily understand that the order can be changed and still remain within the spirit and scope of the various embodiments.

Claims

1. A multi-channel ion detection system for a time-of-flight (TOF) mass analyzer, the multi-channel ion detection system maintaining the resolution of the TOF mass analyzer despite a loss of resolution in one or more channels, the multi-channel ion detection system comprising: A multi-channel detector and an electron multiplier, the multi-channel detector and the electron multiplier being struck by an ion packet of the TOF mass analyzer on a first side of the multi-channel detector and the electron multiplier, converting the strike into multiplied electrons, and emitting the multiplied electrons from two or more segmented electrodes on a second side of the multi-channel detector and the electron multiplier, wherein each of the two or more segmented electrodes corresponds to a strike in a different region of a length across the first side and emits electrons based on the strike; A multi-channel digitizer electrically connected to the two or more segmented electrodes, for each ion packet in the ion packet, the multi-channel digitizer converting the electrons received by each of the two or more segmented electrodes into digital values in channels of the multi-channel digitizer; and A processor that receives digital values from at least two or more channels of the multi-channel digitizer and uses digital values of a predetermined subset of one or more channels known to provide the highest resolution of the at least two or more channels to calculate qualitative information about the ion packet, wherein the qualitative information includes mass-to-charge ratio (m / z) peak shape.

2. The system according to claim 1, wherein the processor further uses the at least two or more channels to calculate quantitative information about the ion packet.

3. The system according to claim 2, wherein, the quantitative information includes m / z peak intensity.

4. The system according to claim 2, wherein the processor calculates quantitative information about the ion packet using digital values from at least two or more channels by: using the intensity of the digital values of the predetermined subset, and using only the intensity of the digital values at each m / z interval of the remaining channels of the at least two or more channels that also includes the intensity of the digital values of the predetermined subset.

5. The system according to claim 2, wherein the processor calculates quantitative information about the ion packet using digital values of the at least two or more channels by: performing m / z peak finding on the digital values of each channel of the at least two or more channels after all ion packets have been received, using the intensity of the digital values of the predetermined subset to construct an optimal resolution m / z peak shape, and using the intensity of the digital values of the at least two or more channels to calculate the total intensity of each m / z peak.

6. The system according to claim 1, wherein the predetermined subset of one or more channels known to provide the highest resolution of the at least two or more channels is determined during an auto-tuning resolution process of the TOF mass analyzer.

7. The system according to claim 1, wherein the multi-channel detector and the electron multiplier are an electrical system or an optoelectronic system.

8. The system according to claim 1, wherein, the multi-channel digitizer includes a multi-channel analog-to-digital converter ADC.

9. The system according to claim 1, wherein, the multi-channel digitizer includes a multi-channel time-to-digital converter TDC.

10. The system according to claim 1, wherein, the predetermined subset includes one channel.

11. The system according to claim 1, wherein, the multi-channel digitizer includes four channels.

12. The system according to claim 11, wherein, the predetermined subset includes two channels.

13. A method for maintaining the resolution of a time-of-flight TOF mass analyzer, despite a loss of resolution in one or more channels of a multi-channel ion detection system of the TOF mass analyzer, the method comprising: using a multi-channel detector and an electron multiplier to convert an impact of an ion packet of the TOF mass analyzer on a first side of the multi-channel detector and the electron multiplier into multiplied electrons, and emitting the multiplied electrons from two or more segmented electrodes on a second side of the multi-channel detector and the electron multiplier, wherein each of the two or more segmented electrodes corresponds to an impact in a different region across the length of the first side and emits electrons based on the impact; for each ion packet in the ion packet, using a multi-channel digitizer to convert the electrons received by each of the two or more segmented electrodes into digital values in the channels of the multi-channel digitizer; and receiving digital values from at least two or more channels of the multi-channel digitizer, using a processor and using digital values of a predetermined subset of one or more channels known to provide the highest resolution of the at least two or more channels to calculate qualitative information about the ion packet, wherein the qualitative information includes a mass-to-charge ratio m / z peak shape.

14. A computer program product, comprising a non-transitory and tangible computer-readable storage medium, the content of the computer-readable storage medium including a program having instructions that, when executed on a processor, perform a method for maintaining the resolution of a time-of-flight TOF mass analyzer, despite a loss of resolution in one or more channels of a multi-channel ion detection system of the TOF mass analyzer, the method comprising: providing a system, wherein the system includes one or more different software modules, and wherein the different software modules include a measurement module and an analysis module; using the measurement module to instruct a multi-channel detector and an electron multiplier to convert an impact of an ion packet of the TOF mass analyzer on a first side of the multi-channel detector and the electron multiplier into multiplied electrons, and emitting the multiplied electrons from two or more segmented electrodes on a second side of the multi-channel detector and the electron multiplier, wherein each of the two or more segmented electrodes corresponds to an impact in a different region across the length of the first side and emits electrons based on the impact; For each ion packet in the ion packet, use the measurement module to instruct the multi-channel digitizer to convert the electrons received by each of the two or more segmented electrodes into digital values in the channels of the multi-channel digitizer; and Use the analysis module to receive digital values from at least two or more channels of the multi-channel digitizer, and use the digital values of a predetermined subset of one or more channels known to provide the highest resolution of the at least two or more channels to calculate qualitative information of the ion packet, where the qualitative information includes the mass-to-charge ratio m / z peak shape.

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