From The DOE’s Los Alamos National Laboratory : “Experiment results confirm anomaly suggesting new physics possibility”

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From The DOE’s Los Alamos National Laboratory

June 16, 2022

Brian Keenan
(505) 412-8561
bkeenan@lanl.gov

Sterile neutrino, physics fundamentals among interpretations of anomalous results.

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Located deep underground at the Baksan Neutrino Observatory in the Caucasus mountains in Russia, the completed two-zone gallium target, at left, contains an inner and outer tank of gallium, which is irradiated by an electron neutrino source. CREDIT: A.A. Shikhin.

New scientific results confirm an anomaly seen in previous experiments, which may point to an as-yet-unconfirmed new elementary particle, the sterile neutrino, or indicate the need for a new interpretation of an aspect of standard model physics, such as the neutrino cross section, first measured 60 years ago.

Los Alamos National Laboratory is the lead American institution collaborating on the Baksan Experiment on Sterile Transitions (BEST) experiment, results of which were recently published in the journals Physical Review Letters and Physical Review C.

“The results are very exciting,” said Steve Elliott, lead analyst of one of the teams evaluating the data and a member of Los Alamos’ Physics division. “This definitely reaffirms the anomaly we’ve seen in previous experiments. But what this means is not obvious. There are now conflicting results about sterile neutrinos. If the results indicate fundamental nuclear or atomic physics are misunderstood, that would be very interesting, too.” Other members of the Los Alamos team include Ralph Massarczyk and Inwook Kim.

More than a mile underground in the Baksan Neutrino Observatory in Russia’s Caucasus Mountains, BEST used 26 irradiated disks of chromium 51, a synthetic radioisotope of chromium and the 3.4 megacurie source of electron neutrinos, to irradiate an inner and outer tank of gallium, a soft, silvery metal also used in previous experiments, though previously in a one-tank set-up. The reaction between the electron neutrinos from the chromium 51 and the gallium produces the isotope germanium 71.

The measured rate of germanium 71 production was 20-24% lower than expected based on theoretical modeling. That discrepancy is in line with the anomaly seen in previous experiments.

BEST builds on a solar neutrino experiment, the Soviet-American Gallium Experiment (SAGE), in which Los Alamos National Laboratory was a major contributor, starting in the late 1980s. That experiment also used gallium and high intensity neutrino sources. The results of that experiment and others indicated a deficit of electron neutrinos — a discrepancy between the predicted and the actual results that came to be known as the “gallium anomaly.” An interpretation of the deficit could be evidence for oscillations between electron neutrino and sterile neutrino states.

The same anomaly recurred in the BEST experiment. The possible explanations again include oscillation into a sterile neutrino. The hypothetical particle may constitute an important part of dark matter, a prospective form of matter thought to make up the vast majority of the physical universe. That interpretation may need further testing, though, because the measurement for each tank was roughly the same, though lower than expected.

Other explanations for the anomaly include the possibility of a misunderstanding in the theoretical inputs to the experiment — that the physics itself requires reworking. Elliott points out that the cross section of the electron neutrino has never been measured at these energies. For example, a theoretical input to measuring the cross section, which is difficult to confirm, is the electron density at the atomic nucleus.

The experiment’s methodology was thoroughly reviewed to ensure no errors were made in aspects of the research, such as radiation source placement or counting system operations. Future iterations of the experiment, if carried out, may include a different radiation source with higher energy, longer half life, and sensitivity to shorter oscillation wave lengths.

See the full article here .

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The DOE’s Los Alamos National Laboratory mission is to solve national security challenges through scientific excellence.

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DOE’s Los Alamos National Laboratory, a multidisciplinary research institution engaged in strategic science on behalf of national security, is managed by Triad, a public service oriented, national security science organization equally owned by its three founding members: The University of California Texas A&M University, Battelle Memorial Institute (Battelle) for the Department of Energy’s National Nuclear Security Administration. Los Alamos enhances national security by ensuring the safety and reliability of the U.S. nuclear stockpile, developing technologies to reduce threats from weapons of mass destruction, and solving problems related to energy, environment, infrastructure, health, and global security concerns.

The United States Department of Energy (DOE) is a cabinet-level department of the United States Government concerned with the United States’ policies regarding energy and safety in handling nuclear material. Its responsibilities include the nation’s nuclear weapons program; nuclear reactor production for the United States Navy; energy conservation; energy-related research; radioactive waste disposal; and domestic energy production. It also directs research in genomics. the Human Genome Project originated in a DOE initiative. DOE sponsors more research in the physical sciences than any other U.S. federal agency, the majority of which is conducted through its system of National Laboratories. The agency is led by the United States Secretary of Energy, and its headquarters are located in Southwest Washington, D.C., on Independence Avenue in the James V. Forrestal Building, named for James Forrestal, as well as in Germantown, Maryland.

Formation and consolidation

In 1942, during World War II, the United States started the Manhattan Project, a project to develop the atomic bomb, under the eye of the U.S. Army Corps of Engineers. After the war in 1946, the Atomic Energy Commission (AEC) was created to control the future of the project. The Atomic Energy Act of 1946 also created the framework for the first National Laboratories. Among other nuclear projects, the AEC produced fabricated uranium fuel cores at locations such as Fernald Feed Materials Production Center in Cincinnati, Ohio. In 1974, the AEC gave way to the Nuclear Regulatory Commission, which was tasked with regulating the nuclear power industry and the Energy Research and Development Administration, which was tasked to manage the nuclear weapon; naval reactor; and energy development programs.

The 1973 oil crisis called attention to the need to consolidate energy policy. On August 4, 1977, President Jimmy Carter signed into law The Department of Energy Organization Act of 1977 (Pub.L. 95–91, 91 Stat. 565, enacted August 4, 1977), which created the Department of Energy. The new agency, which began operations on October 1, 1977, consolidated the Federal Energy Administration; the Energy Research and Development Administration; the Federal Power Commission; and programs of various other agencies. Former Secretary of Defense James Schlesinger, who served under Presidents Nixon and Ford during the Vietnam War, was appointed as the first secretary.

President Carter created the Department of Energy with the goal of promoting energy conservation and developing alternative sources of energy. He wanted to not be dependent on foreign oil and reduce the use of fossil fuels. With international energy’s future uncertain for America, Carter acted quickly to have the department come into action the first year of his presidency. This was an extremely important issue of the time as the oil crisis was causing shortages and inflation. With the Three-Mile Island disaster, Carter was able to intervene with the help of the department. Carter made switches within the Nuclear Regulatory Commission in this case to fix the management and procedures. This was possible as nuclear energy and weapons are responsibility of the Department of Energy.

Recent

On March 28, 2017, a supervisor in the Office of International Climate and Clean Energy asked staff to avoid the phrases “climate change,” “emissions reduction,” or “Paris Agreement” in written memos, briefings or other written communication. A DOE spokesperson denied that phrases had been banned.

In a May 2019 press release concerning natural gas exports from a Texas facility, the DOE used the term ‘freedom gas’ to refer to natural gas. The phrase originated from a speech made by Secretary Rick Perry in Brussels earlier that month. Washington Governor Jay Inslee decried the term “a joke”.

Facilities

The Department of Energy operates a system of national laboratories and technical facilities for research and development, as follows:

Ames Laboratory
Argonne National Laboratory
Brookhaven National Laboratory
Fermi National Accelerator Laboratory
Idaho National Laboratory
Lawrence Berkeley National Laboratory
Lawrence Livermore National Laboratory
Los Alamos National Laboratory
National Energy Technology Laboratory
National Renewable Energy Laboratory
Oak Ridge National Laboratory
Pacific Northwest National Laboratory
Princeton Plasma Physics Laboratory
Sandia National Laboratories
Savannah River National Laboratory
SLAC National Accelerator Laboratory
Thomas Jefferson National Accelerator Facility

Other major DOE facilities include
Albany Research Center
Bannister Federal Complex
Bettis Atomic Power Laboratory – focuses on the design and development of nuclear power for the U.S. Navy
Kansas City Plant
Knolls Atomic Power Laboratory – operates for Naval Reactors Program Research under the DOE (not a National Laboratory)
National Petroleum Technology Office
Nevada Test Site
New Brunswick Laboratory
Office of River Protection
Pantex
Radiological and Environmental Laboratory
Y-12 National Security Complex
Yucca Mountain nuclear waste repository
Other:

Pahute Mesa Airstrip – Nye County, Nevada, in supporting Nevada National Security Site