From The Johannes Gutenberg University Mainz [Johannes Gutenberg-Universität Mainz] (DE): “Worldwide coordinated search for dark matter”

From The Johannes Gutenberg University Mainz [Johannes Gutenberg-Universität Mainz] (DE)

20 January 2022

Professor Dr. Dmitry Budker
Quantum, Atomic, and Neutron Physics (QUANTUM)
Institute of Physics
Johannes Gutenberg University Mainz
and
PRISMA+ Cluster of Excellence
and
Helmholtz Institute – Mainz [Helmholtz-Institut Mainz](DE)
55099 Mainz
Tel.: +49 6131 39-27414
budker@uni-mainz.de

An international team of researchers with key participation from the PRISMA+ Cluster of Excellence at Johannes Gutenberg University Mainz (JGU) and The Helmholtz Institute – Mainz [Helmholtz-Institut Mainz](DE) has published for the first time comprehensive data on the search for dark matter using a worldwide network of optical magnetometers.

1
Sketch of the worldwide GNOME network. ©: Hector Masia Roig.

2
Mainz-based setup of the GNOME Network. Photo: Hector Masia Roig.

According to the scientists, Dark Matter fields should produce a characteristic signal pattern that can be detected by correlated measurements at multiple stations of the GNOME network. Analysis of data from a one-month continuous GNOME operation has not yet yielded a corresponding indication. However, the measurement allows to formulate constraints on the characteristics of Dark Matter, as the researchers report in the prestigious journal Nature Physics.

GNOME stands for Global Network of Optical Magnetometers for Exotic Physics Searches. Behind it are magnetometers distributed around the world in Germany, Serbia, Poland, Israel, South Korea, China, Australia, and the United States. With GNOME, the researchers particularly want to advance the search for Dark Matter – one of the most exciting challenges of fundamental physics in the 21st century. After all, it has long been known that many puzzling astronomical observations, such as the rotation speed of stars in galaxies or the spectrum of the cosmic background radiation, can best be explained by Dark Matter.

“Extremely light bosonic particles are considered one of the most promising candidates for Dark Matter today. These include so-called axion-like particles – ALPs for short,” said Professor Dr. Dmitry Budker, professor at PRISMA+ and at HIM, an institutional collaboration of Johannes Gutenberg University Mainz and The GSI Helmholtz Centre for Heavy Ion Research [GSI Helmholtzzentrum für Schwerionenforschung-Darmstadt](DE). “They can also be considered as a classical field oscillating with a certain frequency. A peculiarity of such bosonic fields is that – according to a possible theoretical scenario – they can form patterns and structures. As a result, the density of Dark Matter could be concentrated in many different regions – discrete domain walls smaller than a galaxy but much larger than Earth could form, for example.”

“If such a wall encounters the Earth, it is gradually detected by the GNOME network and can cause transient characteristic signal patterns in the magnetometers,” explained Dr. Arne Wickenbrock, one of the study’s co-authors. “Even more, the signals are correlated with each other in certain ways – depending on how fast the wall is moving and when it reaches each location.”

The network meanwhile consists of 14 magnetometers distributed over eight countries worldwide-nine of them provided data for the current analysis. The measurement principle is based on an interaction of dark matter with the nuclear spins of the atoms in the magnetometer. The atoms are excited with a laser at a specific frequency, orienting the nuclear spins in one direction. A potential dark matter field can disturb this direction, which is measurable.

Figuratively speaking, one can imagine that the atoms in the magnetometer initially dance around in confusion, as clarified by Hector Masia-Roig, a doctoral student in the Budker group and also an author of the current study. “When they “hear” the right frequency of laser light, they all spin together. Dark Matter particles can throw the dancing atoms out of balance. We can measure this perturbation very precisely.” Now the network of magnetometers becomes important: When the Earth moves through a spatially limited wall of Dark Matter, the dancing atoms in all stations are gradually disturbed. One of these stations is located in a laboratory at the Helmholtz Institute in Mainz. “Only when we match the signals from all the stations can we assess what triggered the disturbance,”said Masia-Roig. “Applied to the image of the dancing atoms, this means: If we compare the measurement results from all the stations, we can decide whether it was just one brave dancer dancing out of line or actually a global dark matter disturbance.”

In the current study, the research team analyzes data from a one-month continuous operation of GNOME. The result: Statistically significant signals did not appear in the investigated mass range from one femtoelectronvolt (feV) to 100,000 feV. Conversely, this means that the researchers can narrow down the range in which such signals could theoretically be found even further than before. For scenarios that rely on discrete Dark Matter walls, this is an important result – “even though we have not yet been able to detect such a domain wall with our global ring search,” added Joseph Smiga, another PhD student in Mainz and author of the study.

Future work of the GNOME collaboration will focus on improving both the magnetometers themselves and the data analysis. In particular, continuous operation should be even more stable. This is important to reliably search for signals that last longer than an hour. In addition, the previous alkali atoms in the magnetometers are to be replaced by noble gases. Under the title “Advanced GNOME”, the researchers expect this to result in considerably better sensitivity for future measurements in the search for ALPs and Dark Matter.

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Dark Matter Background
Fritz Zwicky discovered Dark Matter in the 1930s when observing the movement of the Coma Cluster., Vera Rubin a Woman in STEM, denied the Nobel, some 30 years later, did most of the work on Dark Matter.

Fritz Zwicky.
Coma cluster via NASA/ESA Hubble, the original example of Dark Matter discovered during observations by Fritz Zwicky and confirmed 30 years later by Vera Rubin.
In modern times, it was astronomer Fritz Zwicky, in the 1930s, who made the first observations of what we now call dark matter. His 1933 observations of the Coma Cluster of galaxies seemed to indicated it has a mass 500 times more than that previously calculated by Edwin Hubble. Furthermore, this extra mass seemed to be completely invisible. Although Zwicky’s observations were initially met with much skepticism, they were later confirmed by other groups of astronomers.

Thirty years later, astronomer Vera Rubin provided a huge piece of evidence for the existence of dark matter. She discovered that the centers of galaxies rotate at the same speed as their extremities, whereas, of course, they should rotate faster. Think of a vinyl LP on a record deck: its center rotates faster than its edge. That’s what logic dictates we should see in galaxies too. But we do not. The only way to explain this is if the whole galaxy is only the center of some much larger structure, as if it is only the label on the LP so to speak, causing the galaxy to have a consistent rotation speed from center to edge.

Vera Rubin, following Zwicky, postulated that the missing structure in galaxies is dark matter. Her ideas were met with much resistance from the astronomical community, but her observations have been confirmed and are seen today as pivotal proof of the existence of dark matter.
Astronomer Vera Rubin at the Lowell Observatory in 1965, worked on Dark Matter (The Carnegie Institution for Science).

Vera Rubin, with Department of Terrestrial Magnetism (DTM) image tube spectrograph attached to the Kitt Peak 84-inch telescope, 1970.

Vera Rubin measuring spectra, worked on Dark Matter(Emilio Segre Visual Archives AIP SPL).
Dark Matter Research

LBNL LZ Dark Matter Experiment (US) xenon detector at Sanford Underground Research Facility(US) Credit: Matt Kapust.

Lamda Cold Dark Matter Accerated Expansion of The universe http scinotions.com the-cosmic-inflation-suggests-the-existence-of-parallel-universes. Credit: Alex Mittelmann.

DAMA at Gran Sasso uses sodium iodide housed in copper to hunt for dark matter LNGS-INFN.

Yale HAYSTAC axion dark matter experiment at Yale’s Wright Lab.

DEAP Dark Matter detector, The DEAP-3600, suspended in the SNOLAB (CA) deep in Sudbury’s Creighton Mine.

The LBNL LZ Dark Matter Experiment (US) Dark Matter project at SURF, Lead, SD, USA.

DAMA-LIBRA Dark Matter experiment at the Italian National Institute for Nuclear Physics’ (INFN’s) Gran Sasso National Laboratories (LNGS) located in the Abruzzo region of central Italy.

DARWIN Dark Matter experiment. A design study for a next-generation, multi-ton dark matter detector in Europe at The University of Zurich [Universität Zürich](CH).

PandaX II Dark Matter experiment at Jin-ping Underground Laboratory (CJPL) in Sichuan, China.

Inside the Axion Dark Matter eXperiment U Washington (US) Credit : Mark Stone U. of Washington. Axion Dark Matter Experiment.
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The The Johannes Gutenberg University Mainz [Johannes Gutenberg-Universität Mainz] (DE) is a public research university in Mainz, Rhineland Palatinate, Germany, named after the printer Johannes Gutenberg since 1946. With approximately 32,000 students (2018) in about 100 schools and clinics, it is among the largest universities in Germany. Starting on 1 January 2005 the university was reorganized into 11 faculties of study.

The university is a member of the German U15, a coalition of fifteen major research-intensive and leading medical universities in Germany. The Johannes Gutenberg University is considered one of the most prestigious universities in Germany.

The university is part of the IT-Cluster Rhine-Main-Neckar. The Johannes Gutenberg University Mainz, The Goethe University Frankfurt(DE) and The Technische Universität Darmstadt(DE) together form the Rhine-Main-Universities (RMU).

The first University of Mainz goes back to the Archbishop of Mainz, Prince-elector and Reichserzkanzler Adolf II von Nassau. At the time, establishing a university required papal approval and Adolf II initiated the approval process during his time in office. The university, however, was first opened in 1477 by Adolf’s successor to the bishopric, Diether von Isenburg. In 1784 the University was opened up for Protestants and Jews (curator Anselm Franz von Betzel). It fastly became one of the largest Catholic universities in Europe with ten chairs in theology alone. In the confusion after the establishment of the Mainz Republic of 1792 and its subsequent recapture by the Prussians, academic activity came to a gradual standstill. In 1798 the university became active again under French governance, and lectures in the department of medicine took place until 1823. Only the faculty of theology continued teaching during the 19th century, albeit as a theological Seminary (since 1877 “College of Philosophy and Theology”).

The current Johannes Gutenberg University Mainz was founded in 1946 by the French occupying power. In a decree on 1 March the French military government implied that the University of Mainz would continue to exist: the University shall be “enabled to resume its function”. The remains of anti-aircraft warfare barracks erected in 1938 after the remilitarization of the Rhineland during the Third Reich served as the university’s first buildings and are still in use today.

The continuation of academic activity between the old university and Johannes Gutenberg University Mainz, in spite of an interruption spanning over 100 years, is contested. During the time up to its reopening only a seminary and midwifery college survived.

In 1972, the effect of the 1968 student protests began to take a toll on the University’s structure. The departments (Fakultäten) were dismantled and the University was organized into broad fields of study (Fachbereiche). Finally in 1974 Peter Schneider was elected as the first president of what was now a “constituted group-university” institute of higher education. In 1990 Jürgen Zöllner became University President yet spent only a year in the position after he was appointed Minister for “Science and Advanced Education” for the State of Rhineland-Palatinate. As the coordinator for the SPD’s higher education policy, this furloughed professor from the Institute for Physiological Chemistry played a decisive role in the SPD’s higher education policy and in the development of Study Accounts.