Hello my name is Pepijn Kruidenier and I am here to tell you more about my research.

To do this let me first share my screen. There we go. Alright!

My research was done with a group called KM3NeT, who are in the process of building two neutrino telescopes.

These two telescopes are called ARCA and ORCA, and both have a different goal. ARCA

attempts at studying the origin of the neutrinos while ORCA will study

the properties of the neutrino. A Neutrino is a particle with no charge, and almost no mass. They

are almost nothing at all, and because of this they are often called

ghost particles. They can travel through anything and only rarely interact with matter, through one of

the four fundamental forces. This is called the weak force and it only acts on very small distances and, as the name would suggest, the force

is extremely weak. Despite these particles being ghosts, they are everywhere! Every second, over sixty billion neutrinos travelling

from the sun pass through your fingernail. By studying these ghost particles we can figure out the fusion processes going on in the sun. Neutrinos

are produced in different processes occurring in the

Universe and as they rarely interact, neutrinos can travel directly from these sources to earth, passing through

anything in its way. So, with neutrinos we can study objects that are invisible otherwise. By doing so, phenomena such as the big bang

or supernovae’s can be studied. So, KM3NeT attempts to detect these neutrinos using advanced neutrino telescopes.

These telescopes have one or two building blocks, which consists of 115 vertical strings which are attached to the bottom of the Mediterranean ocean.

Each string will have 18 digital optical modules,DOM's and in each DOM there are 31 photo-multiplier tubes, PMT's.

In the rare occasion that the neutrino interacts with a proton or neutron, , it creates particles that travel faster than the speed of light under water.

When a particle travels faster than the speed of light under water, it emits blu

e light named Cherenov light. This light is detected by the PMT and the DOM

can store at what time, position and brightness the PMT detected the light. If the scientists at KM3Net want to measure where the neutrino

came from, they need to calculate the direction of the neutrino, which

they can with an uncertainty. My research was to help minimize this uncertainty by looking for a particle

that is called a muon. When a neutrino interacts

with a proton or a neutron, a possible scenario is that a hadronic cascade or shower is produced. A hadron

is a particle made up of quarks, and quarks are the fundamental constituent

of matter. A hadronic shower starts with a produced hadron, which can decay and interact

with matter. Each time it does this, more hadrons are produced. In hadronic showers, muons can be produced. These muons, unlike the

other particles, travel long distances without decaying or interacting with matter.

It emits Cherenkov light, activating PMT’s as it travels through the detector.

Using these activations, KM3NeT can figure out the direction

of the muon. Using the direction of the muon, scientists can improve the uncertainty of the calculated

of the neutrino. However, muon PMT activations are hidden within activations of other particles.

. I have developed a tool that can spot the activations coming from the muon and take them apart from the others. This tool is a group

of decision trees which are boosted. A decision tree works similar to a flowchart that you can find in a gossip magazine.

You start at the top, and at each split a question is asked, depending on the answer you get brought

to a new split and at the end there is final decision. In my research the final decision

is if it was a muon hit or a background hit. The boosted part is that after a tree is made, a new

one is made based off of what the previous trees does wrong. This improves the accuracy of the final decision.

Using these trees, the muon hits can be spotted which other scientists can then use to find the muon

direction and improve the uncertainty on the neutrino direction.

The building of this telescope needs funding from governments, and it is understandable that people would think that their tax money

should not be spent on the study of invisible particles. Like most of particle physics, this research is mainly curiosity

driven. Curiosity driven research has however, shown to contribute to society. Max Planck

and Albert Einstein’s attempts to understand the relationship between waves and particles led to lasers and digital camera production.

Whatever device you are watching this video with right now is most likely working due

to our understanding of quantum physics. The very first particle accelerator was used to accelerate hydrogen

hydrogen ions, now there are over 30,000 operating particle accelerators. Some

of which are used to shrink tumors, help design drugs, filter drinking water and much more. The

study of neutrinos is new and yes, the main goal is curiosity driven however they have the potential to help us understand some of the Universe’s

greatest mysteries. By solving these mysteries, it is impossible to say how our discoveries will contribute

to society, but it is likely to be an investment well worth the money. With the

research at KM3NeT, there are ethical implications to consider. The telescopes are built close to the coast of the Mediterranean

and so it is important to minimize the environmental and cultural impact that they have. One of the detector blocks

blocks is located at a location regarded as an important archeological site due to the presence

of a Bronze age settlement and several shipwrecks. The environmental concerns have been

investigated, and due to the block being so deep in the ocean, underwater deep divers such

as the Cuvier’s beaked whale are of concern. Before the building of the telescopes, an environmental

environmental impact study was performed, to be aware of and minimize the environmental effects.

All in all, my bachelor thesis research has shown to be of potential to help the KM3NeT group

at NIKHEF. There are social and ethical implications to this research but I believe that there are opportunities to contribute

to society and that the ethical issues have been well investigated. Thank you for listening!