An arithmetic device that calculates a gain of a photomultiplier tube includes: an acquisition unit that acquires a digital signal based on a dark pulse output from the photomultiplier tube placed in a dark state; and a calculation unit that calculates a total number of electrons in the dark pulse based on the digital signal and calculates the gain of the photomultiplier tube based on the total number of electrons.

An arithmetic device that calculates a gain of a photomultiplier tube includes: an acquisition unit that acquires a digital signal based on a dark pulse output from the photomultiplier tube placed in a dark state; and a calculation unit that calculates a total number of electrons in the dark pulse based on the digital signal and calculates the gain of the photomultiplier tube based on the total number of electrons.

An internal portion of a photomultiplier tube (PMT) having a reflective photocathode array, and a method for manufacturing the same, are provided. The internal portion of the PMT comprises the reflective photocathode array and at least one dynode structure corresponding to the array of reflective photocathodes. Each reflective photocathode receives light and from the light, generates photoelectrons which then travel towards the at least one dynode structure. Upon the photoelectrons making contact with the at least one dynode structure, the photoelectrons are multiplied.

An internal portion of a photomultiplier tube (PMT) having a reflective photocathode array, and a method for manufacturing the same, are provided. The internal portion of the PMT comprises the reflective photocathode array and at least one dynode structure corresponding to the array of reflective photocathodes. Each reflective photocathode receives light and from the light, generates photoelectrons which then travel towards the at least one dynode structure. Upon the photoelectrons making contact with the at least one dynode structure, the photoelectrons are multiplied.

An arithmetic device that calculates a gain of a photomultiplier tube includes: an acquisition unit that acquires a digital signal based on a dark pulse output from the photomultiplier tube placed in a dark state; and a calculation unit that calculates a total number of electrons in the dark pulse based on the digital signal and calculates the gain of the photomultiplier tube based on the total number of electrons.

An arithmetic device that calculates a gain of a photomultiplier tube includes: an acquisition unit that acquires a digital signal based on a dark pulse output from the photomultiplier tube placed in a dark state; and a calculation unit that calculates a total number of electrons in the dark pulse based on the digital signal and calculates the gain of the photomultiplier tube based on the total number of electrons.

An electron tube includes: a photoelectric surface converting incident light into photoelectrons; a plurality of dynodes and an anode; an insulating substrate holding the dynodes and the anode in a state where the dynodes are electrically insulated from each other, and the dynode and the anode are electrically insulated from each other; and a housing accommodating the dynodes, the anode, and the insulating substrate, wherein the insulating substrate includes: a base layer made of a polycrystalline material and having an electrical insulation property; an intermediate layer made of an amorphous material and having an electrical insulation property; and a surface layer made of a material containing carbon and being smaller in electric resistance than the intermediate layer.

An electron tube includes: a photoelectric surface converting incident light into photoelectrons; a plurality of dynodes and an anode; an insulating substrate holding the dynodes and the anode in a state where the dynodes are electrically insulated from each other, and the dynode and the anode are electrically insulated from each other; and a housing accommodating the dynodes, the anode, and the insulating substrate, wherein the insulating substrate includes: a base layer made of a polycrystalline material and having an electrical insulation property; an intermediate layer made of an amorphous material and having an electrical insulation property; and a surface layer made of a material containing carbon and being smaller in electric resistance than the intermediate layer.

An ion detector includes a conversion dynode including a conversion region where electrons are emitted by incident ions, an electron multiplier including an electron incident surface on which the electrons are incident, and an aperture electrode including an aperture through which the electrons traveling from the conversion region to the electron incident surface pass. The conversion region is a region protruding toward a space where the electrons are emitted.

An ion detector includes a conversion dynode including a conversion region where electrons are emitted by incident ions, an electron multiplier including an electron incident surface on which the electrons are incident, and an aperture electrode including an aperture through which the electrons traveling from the conversion region to the electron incident surface pass. The conversion region is a region protruding toward a space where the electrons are emitted.