For more than a decade, the particle physics community has faced a perplexing puzzle: two experiments, LSND at Los Alamos and MiniBooNE at Fermilab, found hints of neutrino behavior that did not fit the usual assumption that the universe contains three types of neutrinos that have tiny masses and oscillate.
The data from these two experiments suggest that something unusual is going on when low-energy muon neutrinos travel a short distance, less than a kilometer. The answer might be that there are additional types of neutrinos, albeit with properties different from the three “normal” types. These extras are known as sterile neutrinos. A confirmed discovery of a sterile neutrino would open up a whole new world of particles previously hidden from view.
Thanks to new results published by the MiniBooNE collaboration and presented at the Neutrino 2018 conference in Heidelberg this week, this neutrino mystery persists. The new data shows that the MiniBooNE signal has grown even stronger. Significantly stronger. The result suggests that there is almost no chance for the anomalous signal to be explained as merely a statistical fluctuation. (Read the press release from Los Alamos National Laboratory.)
That is exciting and very good news for the MicroBooNE experiment currently operating at Fermilab, as well as the ambitious Short-Baseline Neutrino Program that we are building here at Fermilab, together with our international partners at CERN and institutions in Italy, United Kingdom, Switzerland, Brazil and the United States (funded by the Department of Energy and National Science Foundation). Thanks to the work, vision and determination of neutrino physicists from around the world, we are now in a superb position to solve this neutrino mystery once and for all.
How did we get to this wonderful situation? The SBN Program combines the strengths of several proposals made a number of years ago. Scientists proposed to build a comprehensive set of neutrino detectors in Fermilab’s Booster neutrino beam, which also provided the neutrinos for MiniBooNE. The detectors would measure with great precision neutrino interactions at three locations along the beam, making the best possible measurement for short-baseline neutrino oscillation.
The SBN Program is based on three detectors that all have better particle identification than MiniBooNE thanks to the use of liquid-argon time projection chambers, which is also the technology that will be used for the international Deep Underground Neutrino Experiment hosted by Fermilab. And instead of sampling neutrino oscillations at just one location, as LSND and MiniBooNE did, respectively, the SBN Program will spread the three detectors along a straight line of about 500 meters so that together they can measure how neutrino oscillations unfold along that distance.
The next years will be exciting. The first of the three detectors, named MicroBooNE, is already taking data, and scientists just shared its first results at Neutrino 2018. The ICARUS detector, which was shipped from the Italian National Institute for Nuclear Physics’s Gran Sasso laboratory to CERN in Switzerland for refurbishment and then to Fermilab, will be the next to go online. It should start taking data in about a year. The third detector is known as the Short Baseline Near Detector, or SBND. It will be the closest to the origin of the Booster neutrino beam, at a distance of about 100 meters. Construction of SBND components is coming along well, and the entire detector should be operational in 2020.
Together, these detectors combine to form a powerful experiment to search for sterile neutrinos. The discovery of these particles would change the course of particle physics. Stay tuned.
Joe Lykken is the Fermilab chief research officer.
[Update: Registration is now closed. Thank you to all of the interested photographers.]
Calling all photographers! Registration is now open for the 2018 Photowalk at the U.S. Department of Energy’s Fermi National Accelerator Laboratory.
On July 28, Fermilab will open its doors to 50 amateur and professional photographers for a four-hour behind-the-scenes Photowalk of the laboratory. Photographers will be able to visit, explore and take pictures of scientific machines and locations in research areas not usually accessible to the public.
The Fermilab Photowalk is part of the Global Physics Photowalk, hosted this summer at 16 labs around the world. This year’s event will feature labs and institutions in Australia, Europe and Asia as well as four (Fermilab, Brookhaven National Laboratory in New York, Sanford Underground Research Facility in South Dakota and SLAC National Accelerator Laboratory in California) in the United States.
The Global Physics Photowalk will draw from local and national competitions, with the winning national photos submitted to a global judging panel. The top three photos from Fermilab’s event, as chosen by a jury, will be submitted to the global competition organized by the Interactions collaboration.
Participation in the Fermilab Photowalk will be limited to the first 50 photographers to sign up online. Those who participated in the 2015 Photowalk at Fermilab will not be eligible for the 2018 event. Fermilab employees and users, and their families, are also ineligible.
Fermilab will maintain a waiting list to fill in any cancellations. The July 28 event is free of charge and will run from 8 a.m. to 12:30 p.m. For more information and to register online, please visit http://www.fnal.gov/pub/photowalk.
Fermilab is America’s premier national laboratory for particle physics and accelerator research. A U.S. Department of Energy Office of Science laboratory, Fermilab is located near Chicago, Illinois, and operated under contract by the Fermi Research Alliance LLC, a joint partnership between the University of Chicago and the Universities Research Association Inc. Visit Fermilab’s website at www.fnal.gov and follow us on Twitter at @Fermilab.
The DOE Office of Science is the single largest supporter of basic research in the physical sciences in the United States and is working to address some of the most pressing challenges of our time. For more information, please visit science.energy.gov.
The international Deep Underground Neutrino Experiment collaboration, hosted by the U.S. Department of Energy’s Fermilab, continues to grow. During the collaboration meeting at Fermilab from May 14-18, the DUNE Institutional Board admitted two new institutions to the collaboration: the Laboratory of Instrumentation and Experimental Particle Physics, which is the first institution from Portugal to join DUNE, and the University of Bucharest, the second institution from Romania. The collaboration now comprises 1,061 scientists from 175 institutions in 32 countries.
“The DUNE collaboration is growing at a rate of about 100 people per year,” said co-spokesperson Stefan Soldner-Rembold, professor at the University of Manchester in the UK. “About 60 percent of the 175 institutions on DUNE are from outside the United States.”
A substantial portion of the collaboration meeting was devoted to the upcoming operation of two DUNE prototype detectors at the European research center CERN, known as ProtoDUNE, with speakers presenting the updates on the construction happening this spring.
“There has been really remarkable progress,” said DUNE co-spokesperson Ed Blucher, professor at the University of Chicago. “Congratulations to the installation teams at CERN for their incredible efforts on the two ProtoDUNE detectors. Both are on track to collect data that will be important for finalizing the specifications of the liquid-argon detectors for the DUNE experiment.”
In addition to hosting the construction of the prototype detectors, CERN also will provide the cryostat for the first DUNE detector module to be installed at the Sanford Underground Research Laboratory in South Dakota, housed by the Long-Baseline Neutrino Facility that will be constructed at Fermilab and Sanford Lab.
Construction of the single-phase ProtoDUNE detector at CERN. Photo: CERN
“ProtoDUNE is a fundamental step towards many technological aspects of LBNF/DUNE,” said Marzio Nessi, leader of the CERN Neutrino Platform. “Before embarking on a multikiloton liquid-argon detector about 1.5 kilometers underground at Sanford Lab, we have to prove at the kiloton scale that we master the construction and operation of the large modular cryostats, that we are able to obtain the required purity of the liquid argon, and that we are able to keep the high-voltage electric field inside the detector at the nominal value, without discharges. ProtoDUNE is the first step, which will give us confidence that we are on the right track.”
Filling of the first prototype detector at CERN with liquid argon, known as single-phase ProtoDUNE detector, is anticipated to begin in June.
“Completion of the huge protoDUNE detector in little over two years from approval is an extraordinary achievement by groups on both sides of the Atlantic,” said ProtoDUNE co-leader Christos Touramanis, professor at the University of Liverpool in the UK. “It fills us with confidence that the ambitious DUNE construction schedule will be met.”
The first ProtoDUNE detector will start recording particle tracks later this year.
“It has been an incredible team effort bringing together the ProtoDUNE detector elements constructed in the U.S. and UK,” said ProtoDUNE Construction Coordinator Regina Rameika of Fermilab. “The support we have received from CERN for the installation has been amazing. We are now looking forward to operating the detector.”
The construction of the second prototype detector at CERN, known as the dual-phase ProtoDUNE detector, also is progressing well.
“In the last months, the progress in the construction and test of the various components of the second DUNE prototype detector at CERN has changed gear,” said Filippo Resnati, the technical coordinator of the Neutrino Platform at CERN. “The field cage is fully installed and has been tested at 150,000 volts. In June, the first 3-meter-by-3-meter signal-amplification system will be ready to be extensively tested in realistic thermodynamic conditions. Light readout, electronics, data acquisition and detector control systems are in very good shape too. The installation of the detector will be completed in fall of this year.”
Once it is operational, scientists will record cosmic-ray muons to test the detector.
Construction of the dual-phase ProtoDUNE detector at CERN. Photo: CERN
“We are eagerly looking forward to the completion and the operation of the dual-phase ProtoDUNE detector,” said CNRS Research DIrector Dario Autiero of the French National Institute of Nuclear and Particle Physics. “The innovative design of this prototype is the outcome of a long R&D process. It is aimed at providing DUNE additional handles. The construction effort for this large-scale detector required a strong dedication from many groups and would not have been possible without the fundamental support from CERN.”
Another important topic at the collaboration meeting was the Interim Design Report for the construction of DUNE far detector modules in South Dakota. The document is based on the experience DUNE scientists and engineers gained during the design and construction of the prototype detectors at CERN. It is a step toward the publication of the more detailed Technical Design Report in 2019, which will serve as the blueprint for the construction of the first DUNE far detector modules.
“Within a few months, the recently formed DUNE Far Detector Institutional Consortia — who take responsibility for the construction, installation and commissioning of the different far detector subsystems — were able to provide detailed documentation on the current state of their planning efforts,” said Eric James, DUNE technical coordinator. “Production of the Interim Design Report on such a short time scale sends a strong signal that the collaboration remains on track to meet its goal of producing the Technical Design Reports for the first two far detector modules by spring 2019.”
DUNE now comprises institutions from 32 countries: Armenia, Brazil, Bulgaria, Canada, Chile, China, Colombia, Czech Republic, Finland, France, Greece, India, Iran, Italy, Japan, Madagascar, Mexico, Netherlands, Paraguay, Peru, Poland, Portugal, Romania, Russia, South Korea, Spain, Sweden, Switzerland, Turkey, Ukraine, United Kingdom, and United States. More information is at dunescience.org.
To learn more about the Deep Underground Neutrino Experiment, the Long-Baseline Neutrino Facility that will house the experiment, and the PIP-II particle accelerator project that will power the neutrino beam for the experiment, visit www.fnal.gov/pub/science/lbnf-dune/.