Photomultipliers - Revision history

Thomastheo: added direct link to datasheet, which seems to have disappeared off the internet since last update

2022-07-10T21:05:07Z

added direct link to datasheet, which seems to have disappeared off the internet since last update

← Older revision		Revision as of 21:05, 10 July 2022
Line 37:		Line 37:


	For all other info available on this PMT type, see the general [~~http~~://~~public~~.~~hofstragroup.com~~/3497.pdf datasheet]:		For all other info available on this PMT type, see the general [https://revspace.nl/images/1/1b/3497.pdf datasheet]:

	==Old photomultipliers==		==Old photomultipliers==

Thomastheo at 20:42, 27 July 2017

2017-07-27T20:42:12Z

← Older revision		Revision as of 20:42, 27 July 2017
Line 2:		Line 2:
	\|Name=Photomultipliers		\|Name=Photomultipliers
	\|Picture=Xp2202.jpg		\|Picture=Xp2202.jpg
	\|Status=~~Initializing~~		\|Status=In progress
	\|Contact=thomas		\|Contact=thomas
	\|Photomultiplier and experiments with cheap scintillators.		\|Photomultiplier and experiments with cheap scintillators.

Thomastheo: /* Updates */

2017-07-27T20:40:39Z

Updates

← Older revision		Revision as of 20:40, 27 July 2017
Line 82:		Line 82:

	17-3-2017: Project started		17-3-2017: Project started

			27-7-2017: Acquired a lab-grade linearly regulated supply that is capable of outputting ultrastable bias voltages from 0 to -2500 volts, so the bias supply is now sorted.

Thomastheo: /* Background */

2017-03-18T20:20:19Z

Background

← Older revision		Revision as of 20:20, 18 March 2017
Line 9:		Line 9:
	==Background==		==Background==

	For those unfamiliar with photomultipliers, they are vacuum tube device used for detecting and quantifying incredibly tiny amounts of light, even single photons. When incoming photons of sufficient energy strike the end window, they cause electrons to be emitted inside the tube's vacuum by means of the photoelectric effect. These electrons are then amplified by a high potential difference across a cascade of what are called dynodes. An incident photon liberates only a single electron at the photocathode window, but when it is then accelerated into the first dynode by a potential difference, it kicks off a number of electrons through secondary emission, which then accelerate to the next dynode, kicking off even more electrons, and so on. After this process repeats a dozen or so times (for however many dynodes the tube has), that one photon/electron event will have been amplified with enormous gain, up to six orders of magnitude or more, resulting in a signal that can ~~easily~~ be measured and recorded.		For those unfamiliar with photomultipliers, they are vacuum tube device used for detecting and quantifying incredibly tiny amounts of light, even single photons. When incoming photons of sufficient energy strike the end window, they cause electrons to be emitted inside the tube's vacuum by means of the photoelectric effect. These electrons are then amplified by a high potential difference across a cascade of what are called dynodes. An incident photon liberates only a single electron at the photocathode window, but when it is then accelerated into the first dynode by a potential difference, it kicks off a number of electrons through secondary emission, which then accelerate to the next dynode, kicking off even more electrons, and so on. After this process repeats a dozen or so times (for however many dynodes the tube has), that one photon/electron event will have been amplified with enormous gain, up to six orders of magnitude or more, resulting in a signal that can be measured and recorded.

	They are commonly used as radiation detectors, optically coupled with a material (scintillator) that produces short pulses of light when hit by ionizing radiation. The benefit over their geiger tube cousins is their sensitivity (depending on the size of the scintillator), their versatility (a scintillator can be chosen that is sensitive to different/specific kind of radiation) and their ability (with a suitable scintillator) to not only count pulses, but also measure their energy, allowing for things like spectroscopy. More than one photomultiplier can be coupled to the same scintillator, making it possible to verify with some certainty that a given signal is actually the result of photon emission in the scintillator, which is great for scientific applications.		They are commonly used as radiation detectors, optically coupled with a material (scintillator) that produces short pulses of light when hit by ionizing radiation. The benefit over their geiger tube cousins is their sensitivity (depending on the size of the scintillator), their versatility (a scintillator can be chosen that is sensitive to different/specific kind of radiation) and their ability (with a suitable scintillator) to not only count pulses, but also measure their energy, allowing for things like spectroscopy. More than one photomultiplier can be coupled to the same scintillator, making it possible to verify with some certainty that a given signal is actually the result of photon emission in the scintillator, which is great for scientific applications.

Thomastheo: /* Background */

2017-03-17T20:57:35Z

Background

← Older revision		Revision as of 20:57, 17 March 2017
Line 9:		Line 9:
	==Background==		==Background==

	For those unfamiliar with photomultipliers, they are vacuum tube ~~devices~~ used for detecting and quantifying incredibly tiny amounts of light, even single photons. ~~They make use~~ of the photoelectric effect ~~to first 'translate' incoming photons to~~ electrons~~, and~~ then ~~amplify the resulting signal~~ by ~~employing~~ a high potential difference ~~and~~ a cascade of what are called dynodes. An incident photon liberates a single electron at the photocathode window, ~~which~~ is then accelerated into the first dynode by a potential difference, ~~kicking~~ off a number of electrons through secondary emission, which then accelerate to the next dynode, kicking off even more electrons, and so on. After this process repeats a dozen or so times (for however many dynodes the tube has), that one photon/electron event will have been amplified with enormous gain, up to six orders of magnitude or more, resulting in a signal that can easily be measured and recorded.		For those unfamiliar with photomultipliers, they are vacuum tube device used for detecting and quantifying incredibly tiny amounts of light, even single photons. When incoming photons of sufficient energy strike the end window, they cause electrons to be emitted inside the tube's vacuum by means of the photoelectric effect. These electrons are then amplified by a high potential difference across a cascade of what are called dynodes. An incident photon liberates only a single electron at the photocathode window, but when it is then accelerated into the first dynode by a potential difference, it kicks off a number of electrons through secondary emission, which then accelerate to the next dynode, kicking off even more electrons, and so on. After this process repeats a dozen or so times (for however many dynodes the tube has), that one photon/electron event will have been amplified with enormous gain, up to six orders of magnitude or more, resulting in a signal that can easily be measured and recorded.

	They are commonly used as radiation detectors, optically coupled with a material (scintillator) that produces short pulses of light when hit by ionizing radiation. The benefit over their geiger tube cousins is their sensitivity (depending on the size of the scintillator), their versatility (a scintillator can be chosen that is sensitive to different/specific kind of radiation) and their ability (with a suitable scintillator) to not only count pulses, but also measure their energy, allowing for things like spectroscopy. More than one photomultiplier can be coupled to the same scintillator, making it possible to verify with some certainty that a given signal is actually the result of photon emission in the scintillator, which is great for scientific applications.		They are commonly used as radiation detectors, optically coupled with a material (scintillator) that produces short pulses of light when hit by ionizing radiation. The benefit over their geiger tube cousins is their sensitivity (depending on the size of the scintillator), their versatility (a scintillator can be chosen that is sensitive to different/specific kind of radiation) and their ability (with a suitable scintillator) to not only count pulses, but also measure their energy, allowing for things like spectroscopy. More than one photomultiplier can be coupled to the same scintillator, making it possible to verify with some certainty that a given signal is actually the result of photon emission in the scintillator, which is great for scientific applications.

Thomastheo: /* Scintillators */

2017-03-17T17:01:53Z

Scintillators

← Older revision		Revision as of 17:01, 17 March 2017
Line 67:		Line 67:
	Ebay is a great source for relatively inexpensive surplus scintillators of all types. Old soviet doped sodium iodide crystals, modern plastic scintillators, LYSO scintillators, they’re all available. So far I have not been able to find affordable large volume/ surface area scintillators, such as the ‘paddles’ conventionally used for things like muon detectors. This project is meant to be fun, so I’m just not willing to spend piles of money on slabs of plastic. Besides, I think it would instead be fun to try and make a detector/scintillator constructed with more affordable and readily available materials. It certainly doesn’t have to be highly optimized or competitive to be adequate for my purposes.		Ebay is a great source for relatively inexpensive surplus scintillators of all types. Old soviet doped sodium iodide crystals, modern plastic scintillators, LYSO scintillators, they’re all available. So far I have not been able to find affordable large volume/ surface area scintillators, such as the ‘paddles’ conventionally used for things like muon detectors. This project is meant to be fun, so I’m just not willing to spend piles of money on slabs of plastic. Besides, I think it would instead be fun to try and make a detector/scintillator constructed with more affordable and readily available materials. It certainly doesn’t have to be highly optimized or competitive to be adequate for my purposes.

	The first ever scintillator, in use long before the invention of the photomultiplier tube, was silver-activated zinc sulfide. Applied as a thin coating on a screen or membrane, it ~~was~~ used in things like spinthariscopes, fluoroscopes and x-ray photo-cassettes. It’s also responsible for the actual glow emitted by radio-luminescent radium paint (albeit doped with copper, which gives a longer lasting green emission). ZnS screens are inexpensive and available, but due to this compound being quite opaque, they are not useful for constructing high volume detectors. They’re great as alpha probes though, so I will definitely give this a go.		The first ever scintillator, in use long before the invention of the photomultiplier tube, was silver-activated zinc sulfide. Applied as a thin coating on a screen or membrane, it is used in things like spinthariscopes, fluoroscopes and x-ray photo-cassettes. It’s also responsible for the actual glow emitted by radio-luminescent radium paint (albeit doped with copper, which gives a longer lasting green emission). ZnS screens are inexpensive and available, but due to this compound being quite opaque, they are not useful for constructing high volume detectors. They’re great as alpha probes though, so I will definitely give this a go.

	Some other early scintillators were made with various aromatic hydrocarbons, traditionally anthracene, stilbene, and naphthalene. Whereas you won’t find the first two at the corner drugstore, naphthalene is quite commonly available in the form of moth balls. Besides the horrendous smell, there are a number of other downsides, unfortunately. Due to the response of these materials being anisotropic (the amount of light produced by scintillation varies with the angle of incidence of the ionizing radiation) it is not possible to use them in applications where you are looking to determine the energy of any particles you’re detecting (unless the incident radiation is in the form of a collimated beam, but since I don’t have a synchrotron, this is not likely to be relevant to my use case). It’s also quite difficult to grow large transparent crystals from these compounds, which is of course necessary if you want to make practical large volume detectors. One way of getting around that problem is to use a suitable solvent, preferably one that has its own scintillation properties, to make a liquid scintillator.		Some other early scintillators were made with various aromatic hydrocarbons, traditionally anthracene, stilbene, and naphthalene. Whereas you won’t find the first two at the corner drugstore, naphthalene is quite commonly available in the form of moth balls. Besides the horrendous smell, there are a number of other downsides, unfortunately. Due to the response of these materials being anisotropic (the amount of light produced by scintillation varies with the angle of incidence of the ionizing radiation) it is not possible to use them in applications where you are looking to determine the energy of any particles you’re detecting (unless the incident radiation is in the form of a collimated beam, but since I don’t have a synchrotron, this is not likely to be relevant to my use case). It’s also quite difficult to grow large transparent crystals from these compounds, which is of course necessary if you want to make practical large volume detectors. One way of getting around that problem is to use a suitable solvent, preferably one that has its own scintillation properties, to make a liquid scintillator.

Thomastheo: /* Updates */

2017-03-17T12:21:54Z

Updates

← Older revision		Revision as of 12:21, 17 March 2017
Line 79:		Line 79:
	==Updates==		==Updates==

	This page is a work in progress~~, and~~ will ~~be updated if and when I have something to report on~~.		This page is a work in progress. I will list major updates here.

			17-3-2017: Project started

Thomastheo: /* Background */

2017-03-17T12:19:43Z

Background

← Older revision		Revision as of 12:19, 17 March 2017
Line 9:		Line 9:
	==Background==		==Background==

	For those unfamiliar with photomultipliers, they are vacuum tube devices used for detecting and quantifying incredibly tiny amounts of light, even single photons. They make use of the photoelectric effect to first 'translate' photons to electrons, and then amplify the resulting signal by employing a high potential difference and a cascade of what are called dynodes. An incident photon liberates a single electron at the photocathode window, which is then accelerated into the first dynode by a potential difference, kicking off a number of electrons through secondary emission, which then accelerate to the next dynode, kicking off even more electrons, and so on. After this process repeats a dozen or so times (for however many dynodes the tube has), that one photon/electron event will have been amplified with enormous gain, up to six orders of magnitude or more, resulting in a signal that can easily be measured and recorded.		For those unfamiliar with photomultipliers, they are vacuum tube devices used for detecting and quantifying incredibly tiny amounts of light, even single photons. They make use of the photoelectric effect to first 'translate' incoming photons to electrons, and then amplify the resulting signal by employing a high potential difference and a cascade of what are called dynodes. An incident photon liberates a single electron at the photocathode window, which is then accelerated into the first dynode by a potential difference, kicking off a number of electrons through secondary emission, which then accelerate to the next dynode, kicking off even more electrons, and so on. After this process repeats a dozen or so times (for however many dynodes the tube has), that one photon/electron event will have been amplified with enormous gain, up to six orders of magnitude or more, resulting in a signal that can easily be measured and recorded.

	They are commonly used as radiation detectors, optically coupled with a material (scintillator) that produces short pulses of light when hit by ionizing radiation. The benefit over their geiger tube cousins is their sensitivity (depending on the size of the scintillator), their versatility (a scintillator can be chosen that is sensitive to different/specific kind of radiation) and their ability (with a suitable scintillator) to not only count pulses, but also measure their energy, allowing for things like spectroscopy. More than one photomultiplier can be coupled to the same scintillator, making it possible to verify with some certainty that a given signal is actually the result of photon emission in the scintillator, which is great for scientific applications.		They are commonly used as radiation detectors, optically coupled with a material (scintillator) that produces short pulses of light when hit by ionizing radiation. The benefit over their geiger tube cousins is their sensitivity (depending on the size of the scintillator), their versatility (a scintillator can be chosen that is sensitive to different/specific kind of radiation) and their ability (with a suitable scintillator) to not only count pulses, but also measure their energy, allowing for things like spectroscopy. More than one photomultiplier can be coupled to the same scintillator, making it possible to verify with some certainty that a given signal is actually the result of photon emission in the scintillator, which is great for scientific applications.

Thomastheo: /* Specifications */

2017-03-17T12:13:53Z

Specifications

← Older revision		Revision as of 12:13, 17 March 2017
Line 19:		Line 19:
	==Specifications==		==Specifications==

	The tubes I bought are chunky 2’’ units, with a bialkali photocathode composition that has a spectral sensitivity specifically designed to correspond well with the emissions of traditional scintillator materials~~, used in the detection of ionizing radiation~~. They seem to be quite high-end, tailored specifically for research applications, so I imagine they will be quite suitable for what I intend to do with them. I have four to play with.		The tubes I bought are chunky 2’’ units, with a bialkali photocathode composition that has a spectral sensitivity specifically designed to correspond well with the emissions of traditional scintillator materials. They seem to be quite high-end, tailored specifically for research applications, so I imagine they will be quite suitable for what I intend to do with them. I have four to play with.

Thomastheo: /* Scintillators */

2017-03-17T12:08:15Z

Scintillators

← Older revision		Revision as of 12:08, 17 March 2017
Line 69:		Line 69:
	The first ever scintillator, in use long before the invention of the photomultiplier tube, was silver-activated zinc sulfide. Applied as a thin coating on a screen or membrane, it was used in things like spinthariscopes, fluoroscopes and x-ray photo-cassettes. It’s also responsible for the actual glow emitted by radio-luminescent radium paint (albeit doped with copper, which gives a longer lasting green emission). ZnS screens are inexpensive and available, but due to this compound being quite opaque, they are not useful for constructing high volume detectors. They’re great as alpha probes though, so I will definitely give this a go.		The first ever scintillator, in use long before the invention of the photomultiplier tube, was silver-activated zinc sulfide. Applied as a thin coating on a screen or membrane, it was used in things like spinthariscopes, fluoroscopes and x-ray photo-cassettes. It’s also responsible for the actual glow emitted by radio-luminescent radium paint (albeit doped with copper, which gives a longer lasting green emission). ZnS screens are inexpensive and available, but due to this compound being quite opaque, they are not useful for constructing high volume detectors. They’re great as alpha probes though, so I will definitely give this a go.

	Some other early scintillators were made with various aromatic hydrocarbons, traditionally anthracene, stilbene, and naphthalene. Whereas you won’t find the first two at the corner drugstore, naphthalene is quite commonly available in the form of moth balls. Besides the horrendous smell, there are a number of other downsides, unfortunately. Due to the response of these materials being anisotropic (the amount of light produced by scintillation varies with the angle of incidence of the ionizing radiation) it is not possible to use them in applications where you are looking to determine the ~~relative~~ energy of any particles you’re detecting (unless the incident radiation is in the form of a collimated beam, but since I don’t have a synchrotron, this is not likely to be relevant to my use case). It’s also quite difficult to grow large transparent crystals from these compounds, which is of course necessary if you want to make practical large volume detectors. One way of getting around that problem is to use a suitable solvent, preferably one that has its own scintillation properties, to make a liquid scintillator.		Some other early scintillators were made with various aromatic hydrocarbons, traditionally anthracene, stilbene, and naphthalene. Whereas you won’t find the first two at the corner drugstore, naphthalene is quite commonly available in the form of moth balls. Besides the horrendous smell, there are a number of other downsides, unfortunately. Due to the response of these materials being anisotropic (the amount of light produced by scintillation varies with the angle of incidence of the ionizing radiation) it is not possible to use them in applications where you are looking to determine the energy of any particles you’re detecting (unless the incident radiation is in the form of a collimated beam, but since I don’t have a synchrotron, this is not likely to be relevant to my use case). It’s also quite difficult to grow large transparent crystals from these compounds, which is of course necessary if you want to make practical large volume detectors. One way of getting around that problem is to use a suitable solvent, preferably one that has its own scintillation properties, to make a liquid scintillator.

	Liquid scintillators are widely used in physics experiments, with a vast range of liquid cocktails available commercially. I’m not willing to use expensive specifically purified isomers most suitable for scintillation, or particularly nasty solvents such as benzene, so the possible options are quickly whittled down to only a few contenders. The most likely among them is xylene, which is reasonably inexpensive, not excessively hazardous, and happens to be quite suitable in combination with naphthalene.		Liquid scintillators are widely used in physics experiments, with a vast range of liquid cocktails available commercially. I’m not willing to use expensive specifically purified isomers most suitable for scintillation, or particularly nasty solvents such as benzene, so the possible options are quickly whittled down to only a few contenders. The most likely among them is xylene, which is reasonably inexpensive, not excessively hazardous, and happens to be quite suitable in combination with naphthalene.