1 00:00:00,00 --> 00:00:07,230 Hello my name is Pepijn Kruidenier and I am here to tell you more about my research. 2 00:00:07,230 --> 00:00:11,300 To do this let me first share my screen. There we go. Alright! 3 00:00:11,400 --> 00:00:15,310 My research was done with a group called KM3NeT, who are in the process of building two neutrino telescopes. 4 00:00:15,310 --> 00:00:23,800 These two telescopes are called ARCA and ORCA, and both have a different goal. ARCA 5 00:00:23,900 --> 00:00:28,620 attempts at studying the origin of the neutrinos while ORCA will study 6 00:00:28,620 --> 00:00:33,600 the properties of the neutrino. A Neutrino is a particle with no charge, and almost no mass. They 7 00:00:33,700 --> 00:00:37,280 are almost nothing at all, and because of this they are often called 8 00:00:37,280 --> 00:00:43,400 ghost particles. They can travel through anything and only rarely interact with matter, through one of 9 00:00:43,500 --> 00:00:53,200 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 10 00:00:53,300 --> 00:01:03,000 is extremely weak. Despite these particles being ghosts, they are everywhere! Every second, over sixty billion neutrinos travelling 11 00:01:03,100 --> 00:01:12,800 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 12 00:01:12,900 --> 00:01:17,890 are produced in different processes occurring in the 13 00:01:17,890 --> 00:01:22,600 Universe and as they rarely interact, neutrinos can travel directly from these sources to earth, passing through 14 00:01:22,700 --> 00:01:32,400 anything in its way. So, with neutrinos we can study objects that are invisible otherwise. By doing so, phenomena such as the big bang 15 00:01:32,500 --> 00:01:42,200 or supernovae’s can be studied. So, KM3NeT attempts to detect these neutrinos using advanced neutrino telescopes. 16 00:01:42,300 --> 00:01:52,000 These telescopes have one or two building blocks, which consists of 115 vertical strings which are attached to the bottom of the Mediterranean ocean. 17 00:01:52,100 --> 00:02:01,800 Each string will have 18 digital optical modules,DOM's and in each DOM there are 31 photo-multiplier tubes, PMT's. 18 00:02:01,900 --> 00:02:11,600 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. 19 00:02:11,700 --> 00:02:16,110 When a particle travels faster than the speed of light under water, it emits blu 20 00:02:16,110 --> 00:02:21,400 e light named Cherenov light. This light is detected by the PMT and the DOM 21 00:02:21,500 --> 00:02:31,200 can store at what time, position and brightness the PMT detected the light. If the scientists at KM3Net want to measure where the neutrino 22 00:02:31,300 --> 00:02:35,780 came from, they need to calculate the direction of the neutrino, which 23 00:02:35,780 --> 00:02:41,000 they can with an uncertainty. My research was to help minimize this uncertainty by looking for a particle 24 00:02:41,100 --> 00:02:44,130 that is called a muon. When a neutrino interacts 25 00:02:44,130 --> 00:02:50,800 with a proton or a neutron, a possible scenario is that a hadronic cascade or shower is produced. A hadron 26 00:02:50,900 --> 00:02:56,310 is a particle made up of quarks, and quarks are the fundamental constituent 27 00:02:56,310 --> 00:03:00,600 of matter. A hadronic shower starts with a produced hadron, which can decay and interact 28 00:03:00,700 --> 00:03:10,400 with matter. Each time it does this, more hadrons are produced. In hadronic showers, muons can be produced. These muons, unlike the 29 00:03:10,500 --> 00:03:16,050 other particles, travel long distances without decaying or interacting with matter. 30 00:03:16,050 --> 00:03:20,200 It emits Cherenkov light, activating PMT’s as it travels through the detector. 31 00:03:20,300 --> 00:03:26,640 Using these activations, KM3NeT can figure out the direction 32 00:03:26,640 --> 00:03:30,000 of the muon. Using the direction of the muon, scientists can improve the uncertainty of the calculated 33 00:03:30,100 --> 00:03:38,800 of the neutrino. However, muon PMT activations are hidden within activations of other particles. 34 00:03:38,900 --> 00:03:46,400 . 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 35 00:03:46,500 --> 00:03:53,700 of decision trees which are boosted. A decision tree works similar to a flowchart that you can find in a gossip magazine. 36 00:03:53,800 --> 00:03:59,800 You start at the top, and at each split a question is asked, depending on the answer you get brought 37 00:03:59,900 --> 00:04:05,000 to a new split and at the end there is final decision. In my research the final decision 38 00:04:05,100 --> 00:04:11,600 is if it was a muon hit or a background hit. The boosted part is that after a tree is made, a new 39 00:04:11,700 --> 00:04:18,400 one is made based off of what the previous trees does wrong. This improves the accuracy of the final decision. 40 00:04:18,500 --> 00:04:24,900 Using these trees, the muon hits can be spotted which other scientists can then use to find the muon 41 00:04:25,000 --> 00:04:31,100 direction and improve the uncertainty on the neutrino direction. 42 00:04:31,200 --> 00:04:37,500 The building of this telescope needs funding from governments, and it is understandable that people would think that their tax money 43 00:04:38,400 --> 00:04:44,100 should not be spent on the study of invisible particles. Like most of particle physics, this research is mainly curiosity 44 00:04:44,200 --> 00:04:51,600 driven. Curiosity driven research has however, shown to contribute to society. Max Planck 45 00:04:51,700 --> 00:04:58,100 and Albert Einstein’s attempts to understand the relationship between waves and particles led to lasers and digital camera production. 46 00:04:58,200 --> 00:05:03,500 Whatever device you are watching this video with right now is most likely working due 47 00:05:03,600 --> 00:05:10,400 to our understanding of quantum physics. The very first particle accelerator was used to accelerate hydrogen 48 00:05:10,500 --> 00:05:16,700 hydrogen ions, now there are over 30,000 operating particle accelerators. Some 49 00:05:16,800 --> 00:05:23,300 of which are used to shrink tumors, help design drugs, filter drinking water and much more. The 50 00:05:23,400 --> 00:05:30,300 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 51 00:05:30,400 --> 00:05:37,300 greatest mysteries. By solving these mysteries, it is impossible to say how our discoveries will contribute 52 00:05:37,400 --> 00:05:43,900 to society, but it is likely to be an investment well worth the money. With the 53 00:05:44,000 --> 00:05:50,100 research at KM3NeT, there are ethical implications to consider. The telescopes are built close to the coast of the Mediterranean 54 00:05:50,200 --> 00:05:56,900 and so it is important to minimize the environmental and cultural impact that they have. One of the detector blocks 55 00:05:57,000 --> 00:06:02,700 blocks is located at a location regarded as an important archeological site due to the presence 56 00:06:02,800 --> 00:06:09,300 of a Bronze age settlement and several shipwrecks. The environmental concerns have been 57 00:06:09,400 --> 00:06:14,900 investigated, and due to the block being so deep in the ocean, underwater deep divers such 58 00:06:15,000 --> 00:06:21,300 as the Cuvier’s beaked whale are of concern. Before the building of the telescopes, an environmental 59 00:06:21,400 --> 00:06:27,700 environmental impact study was performed, to be aware of and minimize the environmental effects. 60 00:06:27,800 --> 00:06:34,300 All in all, my bachelor thesis research has shown to be of potential to help the KM3NeT group 61 00:06:34,400 --> 00:06:41,800 at NIKHEF. There are social and ethical implications to this research but I believe that there are opportunities to contribute 62 00:06:41,900 --> 00:06:48,500 to society and that the ethical issues have been well investigated. Thank you for listening!