Fermilab's search for sterile neutrinos

Video Statistics and Information

Video
Captions Word Cloud
Reddit Comments
Captions
Fermilab has long been known as one of the world’s  premier accelerator facilities studying neutrinos,   with the first beams being built way back in  the 1970s. Studies of neutrino oscillations   began at Fermilab about two decades ago and it is  anticipated that they will continue for decades   in the future. But the past is the past, and the  future is the future. What neutrino mysteries are   Fermilab scientists studying now? That sounds  like an excellent topic for today’s video.   (intro music) If you were to ask where is the center of the  universe, I would have to tell you that this   is a silly question. In a mind-blowing moment  of physics Zen, the answer is both that there   is no center of the universe and every place  is the center. I made a video about that.   However, if you were to ask where is the center of  the universe for the world’s neutrino accelerator   research program, a strong case could be made  for claiming that it can be found at Fermilab.   The laboratory already has the highest energy  and highest intensity neutrino beam facilities,   delivering nearly a megawatt proton beam  to make those neutrinos. In the future,   upgrades to the accelerator complex will  cross the megawatt threshold. The upgrade   is called the PIP-II program and all of this is  in preparation for the Deep Underground Neutrino   Experiment or DUNE, which will lead to crucial  comparative studies of the behaviors of matter   and antimatter neutrinos. I’ve made several  videos about all of this- really- a whole   bunch- and the links are in the description. But those facilities won’t begin operation and   those questions won’t be answered for years. What  about today’s neutrino questions and facilities?   Let’s talk about both of these in turn. There’s a lot of history here, most of which   I’m going to skip over, but we know of three  different forms of neutrinos that interact via the   weak nuclear force. Those neutrinos are called the  electron neutrino, the muon neutrino, and the tau   neutrino. Each one is called that because they are  usually produced with their cousin particle.   Since the late 1950s, scientists have speculated  that neutrinos might not be immutable and that   they might be able to change their identity in a  process of subatomic switcheroo called neutrino   oscillation. Between 1998 and 2001, a couple of  measurements proved that this idea was true.   Basically, neutrino oscillation means that what  started out as an electron neutrino could turn   into one of the other kinds, much as  if a cat could change into a jaguar,   then into a tiger, and then back again.  I’ve made videos on the topic and,   as usual, the links are in the description. Researchers have worked out the probability that each type of neutrino can convert into the  others. Most of the experiments told a more or   less coherent story, but not all of them. There  have been several experiments that measured more   neutrino transformation than expected. This  has led some to speculate that there exists   at least one undiscovered type of neutrino  that is involved in neutrino oscillation.   However, this fourth neutrino doesn't interact  via the weak nuclear force. Because of this,   we have a special name for this proposed fourth  neutrino and it's called a sterile neutrino.   By the way, I said that there could be one type of  sterile neutrino, but there actually could be more   than one. It’s just simpler for our purposes to  talk about the situation as if there were three   ordinary neutrinos and one sterile neutrino.  If there are more sterile neutrinos, this   doesn’t change what I’ll say in this video. One experiment that reported the possibility  of sterile neutrinos was called the LSND  experiment, performed at the Los Alamos   laboratory in New Mexico. It collected data in  the mid- to late-1990s. The experiment created   muon neutrinos and looked for them to oscillate  into electron neutrinos. The upshot is that they   saw more electron neutrinos than expected. Other experiments have tried to replicate their   observation, but without success. However, the  follow-on experiments used different techniques,   so the fact that they didn’t see the same electron  neutrino appearance rate as LSND isn’t definitive.   Perhaps these later experiments employed  methodologies that were too different.   An experiment called MiniBoone was performed here  at Fermilab to either validate or falsify LSND. It   began operations in 2002. A first result published  in 2007 seemed to rule out LSND, although a later   paper in 2018 seemed to support it. The situation is a little murky because   the experimental techniques back then  weren’t as good as we have today. Indeed,   many of the MiniBoone scientists participated  in a follow-on experiment called MicroBoone,   which employed more sophisticated detector  technologies so that they could get to the   bottom of this sterile neutrino question. MicroBoone used liquid argon to detect and   characterize neutrino interactions.  This is the same technology as will   be used in the DUNE experiment. Liquid argon  gives us a much more precise picture as to   what's going on when neutrinos interact  as compared to the older methodology.   MicroBoone collected data from 2015 to 2021. It  didn’t see the same thing that either LSND or   MiniBoone did, which suggests that maybe sterile  neutrinos aren’t real and definitely makes the   situation even murkier. We need to take the bull  by the horns and get a definitive answer.   So that brings us to the present. Fermilab  has undertaken what is called the short   baseline neutrino program. It’s  called short baseline because,   unlike most neutrino oscillation experiments,  the detectors are close to one another. Indeed,   everything is located on the Fermilab site. So how does the SBN program work? Basically,   it consists of two detectors, both using liquid  argon, to look at neutrino interactions. One   detector is called SBND, for short baseline  near detector, and it's located about 110   meters from the place where the Fermilab  beam hits a target to make neutrinos. The   other detector is called ICARUS, and it's  located about 600 meters from the target.   So, the basic idea is that Fermilab scientists  will extract protons from one of our accelerators   called the booster. The proton will hit a target  and begin a process that will result in a beam   composed predominantly of muon neutrinos.  The neutrinos will first pass through the   SBND detector and then hit the ICARUS detector. This concept is really quite beautiful. The first   detector will measure the exact composition  of the neutrino beam, precisely nailing down   the fractions of electron and muon neutrinos  in the beam. The beam energy is low enough   that tau neutrinos aren’t a consideration. The beam will travel to the second detector,   experiencing neutrino oscillation as it goes. The  ICARUS detector will then make a similarly precise   measurement of the composition of the neutrino  beam after the beam travelled from one detector   to the other. The scientists will then have a  solid measurement of the amount of the neutrino   oscillation that occurred in transit. This two-detector situation is optimum. Because   the two detectors are located near one another  and utilize the same sophisticated detector   technology, it will allow for a very precise  measurement. This is because whatever instrumental   effects occur in one detector will also occur  in the other one. The scientists won't have   to worry about being fooled by different detector  performance. There's no chance for one detector to   zig and the other to zag. If one zigs, both will.  This will reduce measurement uncertainties.   So that’s the plan. Both the SBND and ICARUS  detectors are in place. The beam is the same one   used by the MiniBooNE and MicroBooNE experiments,  so that’s ready to go too. The ICARUS detector was   originally used in Europe, detecting neutrinos  created at CERN. ICARUS is the first neutrino   detector that was built using liquid argon as the  central technology. After completing operations   in Europe, it was moved to Fermilab, where it  began US operations in the summer of 2021.   SBND is still in the final stages of assembly and  shakedown. It's expected to begin data taking in   early 2024. Because it's located close to  the point where the neutrinos are made,   it experiences the most intense beam conditions.  They expect to record at least 20 to 30 times   more neutrino/argon interactions than have  been recorded to date. With so many neutrino   interactions, SBND scientists will also study the  data, looking for possible discoveries beyond the   core program of looking for sterile neutrinos. Looking at the Fermilab neutrino program at a   higher level, having this short baseline  neutrino program has already advanced the   DUNE program and will continue to do so. For example, the scientists developing the SBND   and ICARUS detectors have learned what works and  what doesn’t. All of that technical know-how has   informed the design of the DUNE detector.  In addition, while designing a detector is   all well and good, no detector works exactly as  designed. There will be unexpected idiosyncrasies   in the detector performance. When I talk to  my neutrino colleagues, some of them estimate   that the experience gained by a successful SBN  program will shave a couple of years off the   release of the first DUNE measurement. In addition, particle physics analyses are   usually performed by young scientists or  faculty, supported by their students and   postdoctoral researchers. However, in order to  have young faculty when DUNE begins operations,   those individuals need to be learning the  ropes now. Indeed, today’s SBN students and   postdocs will be some of the most energetic  and impactful analyzers of DUNE data.   There is one other potentially huge benefit  that the SBN program will bequeath to the   DUNE experiment. DUNE is intended to perform a  precision measurement of the differences between   the oscillation properties of neutrinos  and antimatter neutrinos. If it turns out   that the sterile neutrinos exist, getting a  handle on the behavior of sterile neutrinos   will be a crucial step towards achieving  the precision that DUNE is aiming for.   So that’s what the near-term Fermilab neutrino  program will be doing. It has already improved   the technical design of the future DUNE detector.  It is developing the people who will be future   leaders. And, from a scientific point of view,  it will provide critical– perhaps definitive-   measurements that will tell us whether sterile  neutrinos exist or don’t. Fermilab’s current   short baseline neutrino experimental  program is the very foundation on which   future neutrino research success depends. (phasing sound) Okay- so neutrinos are pretty cool. They have   fooled scientists time and time again, from how  they showed in the 1950s that the weak force   interacts differently with matter and antimatter,  to how they surprised scientists in the 1960s when   it became clear that there were different type  of neutrinos. Then there were the hints from   the 1970s through the 1990s that neutrinos  can change their identity. Who knows what   future surprises they hold? That’s what we’re  trying to figure out. If you enjoyed the video,   please like it and subscribe to the channel.  And come back again and again to hear more   similar videos. You’ll be a better person for the  experience and I’m quite confident that you will   come to embrace that fundamental truth of the  universe, which is that physics is everything. (outro music)
Info
Channel: Fermilab
Views: 98,330
Rating: undefined out of 5
Keywords: Fermilab, Physics, neutrinos, neutrino oscillation, Short Baseline Neutrino, SBN, Short Baseline Neutrino Program, Short Baseline Near Detector, SBND, ICARUS, LSND, Liquid Scintillator Neutrino Detector, Los Alamos, Los Alamos National Lab, LAMPF, Los Alamos Meson Production Facility, sterile neutrinos, MiniBooNE, MicroBooNE, neutrino detectors, DUNE, Deep Underground Neutrino Detector, SURF, Sanford Underground Research Facility, CERN, Fermi National Accelerator Laboratory, Don Lincoln
Id: uogLxiTbAKs
Channel Id: undefined
Length: 12min 14sec (734 seconds)
Published: Wed Jan 03 2024
Related Videos
Note
Please note that this website is currently a work in progress! Lots of interesting data and statistics to come.