Certain embodiments described herein are directed to ion detectors and systems. In some examples, the ion detector can include a plurality of dynodes, in which one or more of the dynodes are coupled to an electrometer. In other configurations, each dynode can be coupled to a respective electrometer. Methods using the ion detectors are also described.

In a photodetection unit 100 according to one aspect of the present invention, a photomultiplier 1 and a voltage divider board 132 are electrically connected to each other through a flexible wiring board 120, whereby the photomultiplier 1 can freely set its orientation and achieve a high degree of freedom of installation. In addition, in a voltage divider 130, an insulating resin 136 within a resin case 134 covers around the voltage divider board 132, thereby improving a voltage withstand performance of the voltage divider board 132. This eases restrictions on conditions under which the voltage divider board 132 is installed, whereby the degree of freedom of installation of the photodetection unit 100 is further improved as a whole, which makes it applicable to wider uses.

In a photodetection unit 100 according to one aspect of the present invention, a photomultiplier 1 and a voltage divider board 132 are electrically connected to each other through a flexible wiring board 120, whereby the photomultiplier 1 can freely set its orientation and achieve a high degree of freedom of installation. In addition, in a voltage divider 130, an insulating resin 136 within a resin case 134 covers around the voltage divider board 132, thereby improving a voltage withstand performance of the voltage divider board 132. This eases restrictions on conditions under which the voltage divider board 132 is installed, whereby the degree of freedom of installation of the photodetection unit 100 is further improved as a whole, which makes it applicable to wider uses.

A method for determining a performance parameter of an electron multiplier having a series of electron emissive surfaces forming electron multiplication chain, by comparing a first electron flux of a first electron emissive surface of the electron multiplication chain with a second electron flux of a second electron emissive surface of the electron multiplication chain, or of an electron collector of the electron multiplier. A method of operating an electron multiplier and an electron multiplier or an electron multiplication system is also described.

A method for determining a performance parameter of an electron multiplier having a series of electron emissive surfaces forming electron multiplication chain, by comparing a first electron flux of a first electron emissive surface of the electron multiplication chain with a second electron flux of a second electron emissive surface of the electron multiplication chain, or of an electron collector of the electron multiplier. A method of operating an electron multiplier and an electron multiplier or an electron multiplication system is also described.

A mass spectrometer that includes an MCP detector selects and analyzes a calibrant compound that has a first isotope and a second isotope with a known abundance ratio. The mass spectrometer measures the intensity of the first isotope that produces multiple-ion strikes at the MCP detector and the intensity of the second isotope that produces single-ion strikes at the MCP detector while the bias voltage of the MCP detector is stepped through a sequence of one or more different voltages. At each step, the ratio of the measured intensities is compared to the known abundance ratio for the two isotopes. When the measured ratio is within a predetermined threshold of the known abundance ratio, an optimum voltage for the MCP detector is calculated using one or more measured ratios calculated for voltages of the sequence of voltages.

A mass spectrometer that includes an MCP detector selects and analyzes a calibrant compound that has a first isotope and a second isotope with a known abundance ratio. The mass spectrometer measures the intensity of the first isotope that produces multiple-ion strikes at the MCP detector and the intensity of the second isotope that produces single-ion strikes at the MCP detector while the bias voltage of the MCP detector is stepped through a sequence of one or more different voltages. At each step, the ratio of the measured intensities is compared to the known abundance ratio for the two isotopes. When the measured ratio is within a predetermined threshold of the known abundance ratio, an optimum voltage for the MCP detector is calculated using one or more measured ratios calculated for voltages of the sequence of voltages.