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Nick Ryder
4,234 followers -
Particle physicist
Particle physicist

4,234 followers
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Pointless or profound? The search for sterile neutrinos

Jon Cartwright wrote a feature article for this month's +Physics World on sterile neutrinos. The article covers how one or more sterile neutrinos could solve some of the problems in particle physics, some of the existing evidence that points towards sterile neutrinos and a brief mention of some of the experiments that can shed some light on the matter.

I work on the SoLid experiment. We're currently building a neutrino detector to deploy 5 metres from a nuclear reactor core to look into this issue. I won't weigh in on the question on the front page of Physics World (I clearly hope my work isn't pointless), but I'd be happy to try and answer any questions people have about sterile neutrinos and the experiments looking for them.

(It may be that you need IoP membership to access the article, I read the paper version and haven't found it online yet.)

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Pointless or profound? The search for sterile neutrinos

Jon Cartwright wrote a feature article for this month's +Physics World on sterile neutrinos. The article covers how one or more sterile neutrinos could solve some of the problems in particle physics, some of the existing evidence that points towards sterile neutrinos and a brief mention of some of the experiments that can shed some light on the matter.

I work on the SoLid experiment. We're currently building a neutrino detector to deploy 5 metres from a nuclear reactor core to look into this issue. I won't weigh in on the question on the front page of Physics World (I clearly hope my work isn't pointless), but I'd be happy to try and answer any questions people have about sterile neutrinos and the experiments looking for them.

(It may be that you need IoP membership to access the article, I read the paper version and haven't found it online yet.)

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Pointless or profound? The search for sterile neutrinos

Jon Cartwright wrote a feature article for this month's +Physics World on sterile neutrinos. The article covers how one or more sterile neutrinos could solve some of the problems in particle physics, some of the existing evidence that points towards sterile neutrinos and a brief mention of some of the experiments that can shed some light on the matter.

I work on the SoLid experiment. We're currently building a neutrino detector to deploy 5 metres from a nuclear reactor core to look into this issue. I won't weigh in on the question on the front page of Physics World (I clearly hope my work isn't pointless), but I'd be happy to try and answer any questions people have about sterile neutrinos and the experiments looking for them.

(It may be that you need IoP membership to access the article, I read the paper version and haven't found it online yet.)

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Light sensor PCBs

Designing and making a small PCB to fit inside a custom made 3D printed socket.

Our experiment primarily measures the light emitted when neutrons and positrons interact with our detector. The light is collected in a wavelength shifting optical fibre that is pointed at a light sensor. The sensor converts the optical signal into an electronic pulse that we record. We have some 3D printed sockets that hold the sensor so that the optical fibre is pointing correctly at them. I had to design and make some little PCBs to fit inside the socket and expose a connector for the electrical cable that will connect to them.

We actually have two different plastic socket designs. Our first design was larger and the original plan was to use an existing electrical socket to connect the light sensor to the electrical cable. However, this required stripping the electrical cable, separating the outer and inner wires, crimping each to fit into the electrical socket and also soldering the sensor by hand onto a 2 pin header. This would have taken a lot of time, so instead I designed a PCB to replace the electrical socket.

Designing the PCB was pretty easy because it only has two parts. However the shape and size had to be accurate to ensure a good fit inside the 3D printed part. When I was designing the PCB I realised some simple modifications to the 3D part would make life easier, so we also updated that, making the PCB fit better and reducing the size (which also makes it cheaper).

With help from the physics department's electronics workshop I got the PCB designed and fabricated. I also got some stencils made. To populate the boards solder paste is applied through the stencil. Each board then has a sensor and cable socket placed on it and then they are put through a reflow oven which heats them to the precise temperatures needed to get a good solder joint without overheating the sensors.

Each sensor needs to run at a slightly different voltage. These are assessed by the manufacturers, and then we are given a sheet with the values needed for each sensor. It is important to keep track of which sensor is which, so the PCBs have the serial number of their sensor written on the back.

So far I've soldered sensors onto 50 of the boards since we needed a small batch sent to our collaborators in Belgium quickly. In the next few weeks I'll have to get a few hundred more done by our workshop. This is the first time I've produced boards using a soldering oven, so it was good to learn how to do a new thing.
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Sensor PCBs
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Light sensor PCBs

Designing and making a small PCB to fit inside a custom made 3D printed socket.

Our experiment primarily measures the light emitted when neutrons and positrons interact with our detector. The light is collected in a wavelength shifting optical fibre that is pointed at a light sensor. The sensor converts the optical signal into an electronic pulse that we record. We have some 3D printed sockets that hold the sensor so that the optical fibre is pointing correctly at them. I had to design and make some little PCBs to fit inside the socket and expose a connector for the electrical cable that will connect to them.

We actually have two different plastic socket designs. Our first design was larger and the original plan was to use an existing electrical socket to connect the light sensor to the electrical cable. However, this required stripping the electrical cable, separating the outer and inner wires, crimping each to fit into the electrical socket and also soldering the sensor by hand onto a 2 pin header. This would have taken a lot of time, so instead I designed a PCB to replace the electrical socket.

Designing the PCB was pretty easy because it only has two parts. However the shape and size had to be accurate to ensure a good fit inside the 3D printed part. When I was designing the PCB I realised some simple modifications to the 3D part would make life easier, so we also updated that, making the PCB fit better and reducing the size (which also makes it cheaper).

With help from the physics department's electronics workshop I got the PCB designed and fabricated. I also got some stencils made. To populate the boards solder paste is applied through the stencil. Each board then has a sensor and cable socket placed on it and then they are put through a reflow oven which heats them to the precise temperatures needed to get a good solder joint without overheating the sensors.

Each sensor needs to run at a slightly different voltage. These are assessed by the manufacturers, and then we are given a sheet with the values needed for each sensor. It is important to keep track of which sensor is which, so the PCBs have the serial number of their sensor written on the back.

So far I've soldered sensors onto 50 of the boards since we needed a small batch sent to our collaborators in Belgium quickly. In the next few weeks I'll have to get a few hundred more done by our workshop. This is the first time I've produced boards using a soldering oven, so it was good to learn how to do a new thing.
PhotoVideo
Video
PhotoPhoto
Sensor PCBs
29 Photos - View album

Post has attachment
Light sensor PCBs

Designing and making a small PCB to fit inside a custom made 3D printed socket.

Our experiment primarily measures the light emitted when neutrons and positrons interact with our detector. The light is collected in a wavelength shifting optical fibre that is pointed at a light sensor. The sensor converts the optical signal into an electronic pulse that we record. We have some 3D printed sockets that hold the sensor so that the optical fibre is pointing correctly at them. I had to design and make some little PCBs to fit inside the socket and expose a connector for the electrical cable that will connect to them.

We actually have two different plastic socket designs. Our first design was larger and the original plan was to use an existing electrical socket to connect the light sensor to the electrical cable. However, this required stripping the electrical cable, separating the outer and inner wires, crimping each to fit into the electrical socket and also soldering the sensor by hand onto a 2 pin header. This would have taken a lot of time, so instead I designed a PCB to replace the electrical socket.

Designing the PCB was pretty easy because it only has two parts. However the shape and size had to be accurate to ensure a good fit inside the 3D printed part. When I was designing the PCB I realised some simple modifications to the 3D part would make life easier, so we also updated that, making the PCB fit better and reducing the size (which also makes it cheaper).

With help from the physics department's electronics workshop I got the PCB designed and fabricated. I also got some stencils made. To populate the boards solder paste is applied through the stencil. Each board then has a sensor and cable socket placed on it and then they are put through a reflow oven which heats them to the precise temperatures needed to get a good solder joint without overheating the sensors.

Each sensor needs to run at a slightly different voltage. These are assessed by the manufacturers, and then we are given a sheet with the values needed for each sensor. It is important to keep track of which sensor is which, so the PCBs have the serial number of their sensor written on the back.

So far I've soldered sensors onto 50 of the boards since we needed a small batch sent to our collaborators in Belgium quickly. In the next few weeks I'll have to get a few hundred more done by our workshop. This is the first time I've produced boards using a soldering oven, so it was good to learn how to do a new thing.
PhotoVideo
Video
PhotoPhoto
Sensor PCBs
29 Photos - View album

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Monitoring nuclear reactors using anti-neutrino detectors

I work on the SoLid experiment, which is a novel anti-neutrino detector. The experiment has two goals: 1) to probe the reactor-neutrino anomaly (the neutrino rate detected near reactors is about 8% lower than predicted by theory) and 2) to demonstrate that small scale anti-neutrino detectors can be deployed close to nuclear reactors to monitor both the power of the reactor and the composition of the reactor's fuel.

Patrick Huber and others have just written an article, published in Physics Review Letters, which explains how a neutrino detector placed close to the IR-40 reactor that Iran is currently building could validate that none of the plutonium produced in the reactor is being diverted for weapons purposes. The major advance that using a neutrino detector brings to reactor monitoring is that the rate and energy spectrum of the neutrinos are measured. The rate confirms the power the reactor is producing (which is currently measured using other methods). The energy spectrum of the neutrinos adds additional information about the composition of the fuel inside the reactor. This is possible since the different fissile materials in the reactor each emit neutrinos with different energy spectrum.

An important scenario for monitoring nuclear reactors is the case where the monitoring stops for a period of time. This could be due to technical failures, political issues or an attempt to divert the nuclear material. If monitoring is able to resume some weeks after the disruption then it is important that diversion of nuclear material can be ruled out. If only the power of the reactor is monitored then this is not possible, since burnt fuel containing plutonium could be replaced with fresh fuel and the power could be kept as expected. However, as Huber et al. show, if an anti-neutrino detector is used then the difference in the energy spectrum before and after the disruption can be used to determine if fuel has been diverted within a few months after monitoring resumes.

There are some challenges to getting anti-neutrino detectors working in the difficult conditions on the surface near a reactor, however I hope that SoLid (and other experiments that are starting up) will demonstrate it is possible. They will add an important tool for reactor monitoring that will complement existing tools, they will be easy to deploy at existing or new facilities and will have little or no impact on the operation of the reactors they monitor.

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Monitoring nuclear reactors using anti-neutrino detectors

I work on the SoLid experiment, which is a novel anti-neutrino detector. The experiment has two goals: 1) to probe the reactor-neutrino anomaly (the neutrino rate detected near reactors is about 8% lower than predicted by theory) and 2) to demonstrate that small scale anti-neutrino detectors can be deployed close to nuclear reactors to monitor both the power of the reactor and the composition of the reactor's fuel.

Patrick Huber and others have just written an article, published in Physics Review Letters, which explains how a neutrino detector placed close to the IR-40 reactor that Iran is currently building could validate that none of the plutonium produced in the reactor is being diverted for weapons purposes. The major advance that using a neutrino detector brings to reactor monitoring is that the rate and energy spectrum of the neutrinos are measured. The rate confirms the power the reactor is producing (which is currently measured using other methods). The energy spectrum of the neutrinos adds additional information about the composition of the fuel inside the reactor. This is possible since the different fissile materials in the reactor each emit neutrinos with different energy spectrum.

An important scenario for monitoring nuclear reactors is the case where the monitoring stops for a period of time. This could be due to technical failures, political issues or an attempt to divert the nuclear material. If monitoring is able to resume some weeks after the disruption then it is important that diversion of nuclear material can be ruled out. If only the power of the reactor is monitored then this is not possible, since burnt fuel containing plutonium could be replaced with fresh fuel and the power could be kept as expected. However, as Huber et al. show, if an anti-neutrino detector is used then the difference in the energy spectrum before and after the disruption can be used to determine if fuel has been diverted within a few months after monitoring resumes.

There are some challenges to getting anti-neutrino detectors working in the difficult conditions on the surface near a reactor, however I hope that SoLid (and other experiments that are starting up) will demonstrate it is possible. They will add an important tool for reactor monitoring that will complement existing tools, they will be easy to deploy at existing or new facilities and will have little or no impact on the operation of the reactors they monitor.

Post has attachment
Monitoring nuclear reactors using anti-neutrino detectors

I work on the SoLid experiment, which is a novel anti-neutrino detector. The experiment has two goals: 1) to probe the reactor-neutrino anomaly (the neutrino rate detected near reactors is about 8% lower than predicted by theory) and 2) to demonstrate that small scale anti-neutrino detectors can be deployed close to nuclear reactors to monitor both the power of the reactor and the composition of the reactor's fuel.

Patrick Huber and others have just written an article, published in Physics Review Letters, which explains how a neutrino detector placed close to the IR-40 reactor that Iran is currently building could validate that none of the plutonium produced in the reactor is being diverted for weapons purposes. The major advance that using a neutrino detector brings to reactor monitoring is that the rate and energy spectrum of the neutrinos are measured. The rate confirms the power the reactor is producing (which is currently measured using other methods). The energy spectrum of the neutrinos adds additional information about the composition of the fuel inside the reactor. This is possible since the different fissile materials in the reactor each emit neutrinos with different energy spectrum.

An important scenario for monitoring nuclear reactors is the case where the monitoring stops for a period of time. This could be due to technical failures, political issues or an attempt to divert the nuclear material. If monitoring is able to resume some weeks after the disruption then it is important that diversion of nuclear material can be ruled out. If only the power of the reactor is monitored then this is not possible, since burnt fuel containing plutonium could be replaced with fresh fuel and the power could be kept as expected. However, as Huber et al. show, if an anti-neutrino detector is used then the difference in the energy spectrum before and after the disruption can be used to determine if fuel has been diverted within a few months after monitoring resumes.

There are some challenges to getting anti-neutrino detectors working in the difficult conditions on the surface near a reactor, however I hope that SoLid (and other experiments that are starting up) will demonstrate it is possible. They will add an important tool for reactor monitoring that will complement existing tools, they will be easy to deploy at existing or new facilities and will have little or no impact on the operation of the reactors they monitor.

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Interesting news from the Neutrino 2014 conference.
Unexpected excess in the energy spectrum of anti-neutrinos from nuclear reactors

This week I'm in Boston at the Neutrino 2014 conference (http://neutrino2014.bu.edu/) . Yesterday an interesting result was announced by two reactor neutrino experiments. Both the RENO experiment and the Double Chooz experiment measure the energy spectrum of anti-neutrinos from nuclear reactors. They both see an excess of events with an energy around 5 MeV when compared to the expected energy spectrum. The Daya Bay experiment should also have seen the same excess, but they would not say anything about it yet.

The cause of the excess is unknown. It is possible that the excess is caused by a subtlety in how the two experiments perform their measurements. Perhaps more likely the expected energy spectrum is wrong. These come from a combination of calculations with experimental data used as an input. The process involves calculating the energy spectrum from many different nuclear decay chains. The calculation is complicated and done in a similar way for all of the experiments.

Now that the excess has been announced by two experiments I'm eagerly awaiting papers from them (and Daya Bay) explaining the tests they have performed to ensure this isn't a quirk in their detector or data analysis methods, but really from the nuclear reactors. Then we'll need some more experiments and perhaps improved calculations of the expected spectrum to really pin down what is going on. In a few years my experiment, SoLid, which will measure the neutrino energy spectrum a few metres from a nuclear reactor might have some data to help answer this question.

 
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Reactor flux 5 excess, neutrino 2013
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