Tag Archives: Detector

Physicists Start Construction of Groundbreaking Graviton Detector

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Igor Pikovsky, a physicist at Stevens Institute of Technology, along with his team, is pioneering an innovative experiment aimed at capturing individual gravitons—particles previously believed to be nearly undetectable. This groundbreaking work signals a new era in quantum gravity research.

Expected detection of single graviton signatures from gravitational waves in future experiments. Image credit: I. Pikovski.

Modern physics faces a significant challenge. The two foundational pillars—quantum theory and Einstein’s general theory of relativity—appear contradictory at a glance.

While quantum theory depicts nature through discrete quantum particles and interactions, general relativity interprets gravity as the smooth curvature of space and time.

A true unification demands that gravity be quantum in nature, mediated by particles called gravitons.

For a long time, detecting even a single graviton was deemed nearly impossible.

Consequently, the problem of quantum gravity has mostly remained a theoretical concept, with no experimental framework for a unified theory in view.

In 2024, Dr. Pikovsky and his collaborators from Stevens Institute of Technology, Stockholm University, Okinawa Institute of Science and Technology, and Nordita demonstrated that *detecting gravitons* is indeed feasible.

“For ages, the idea of detecting gravitons seemed hopeless, which is why it wasn’t considered an experimental question,” Pikovsky stated.

“Our findings indicate that this conclusion is outdated, especially with today’s advanced quantum technologies.”

The breakthrough stems from a fresh perspective that combines two pivotal experimental innovations.

The first is the detection of gravitational waves—ripples in spacetime generated by collisions between black holes and neutron stars.

The second innovation is the advancement in quantum engineering. Over the last decade, physicists have mastered the cooling, control, and measurement of larger systems in true quantum states, leading to extraordinary quantum phenomena beyond the atomic scale.

In a landmark experiment in 2022, a team led by Yale University professor Jack Harris showcased the control and measurement of individual vibrational quanta of superfluid helium exceeding 1 nanogram in weight.

Dr. Pikovsky and his co-authors realized that by merging these two advancements, it becomes possible to absorb and detect a single graviton. A passing gravitational wave could, theoretically, transfer exactly one quantum of energy (or one graviton) into a sufficiently large quantum system.

The resulting energy shift may be minimal but manageable. The primary hurdle lies in the fact that gravitons seldom interact with matter.

Nevertheless, in quantum systems scaled to the kilogram level, it is feasible to absorb a single graviton in the presence of strong gravitational waves generated by black hole or neutron star mergers.

Thanks to this recent revelation, Dr. Pikovsky and Professor Harris are collaborating to construct the world’s first experiment specifically designed to detect individual gravitons.

With backing from the WM Keck Foundation, they are engineering centimeter-scale superfluid helium resonators, moving closer to the conditions needed to absorb single gravitons from astrophysical gravitational waves.

“We already possess essential tools; we can detect single quanta in macroscopic quantum systems; it’s merely a matter of scaling up,” Professor Harris elaborated.

The objective of this experiment is to immerse a gram-scale cylindrical resonator within a superfluid helium container, cool the setup to the quantum ground state, and utilize laser-based measurements to detect individual phonons (the vibrational quanta transformed from gravitons).

This detector builds upon an existing laboratory system while advancing into uncharted territory—scaling masses to the gram level while maintaining exceptional quantum sensitivity.

Successfully demonstrating this platform sets the stage for the next iteration, which will be optimized for the sensitivity required to achieve direct detection of gravitons, thus opening new experimental avenues in quantum gravity.

“Quantum physics began with controlled experiments involving light and matter,” Pikovsky noted.

“Our current aim is to bring gravity into this experimental domain and investigate gravitons much like physicists studied photons over a century ago.”

Source: www.sci.news

Inside the World’s Top Dark Matter Detector: What It’s Really Like to Operate

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Chamkaur Ghag plays a pivotal role in the Lux-Zeplin experiment, a leading dark matter detector

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Deep underground in South Dakota, the most advanced dark matter detector on Earth awaits its moment of discovery. This is the Lux-Zeplin (LZ) experiment, highlighting a vast tank of liquid xenon. Physicist Shankaur Ghag from University College London is among the key leaders in this large scientific collaboration, which aims to unravel about 85% of the universe’s mysteries that still elude us.

Currently, Ghag and his team find themselves at a crucial juncture in the quest for this elusive substance. They are considering plans for a more significant detector called xlzd, which promises to be many times the size of the LZ and even more precise. However, if neither detector can uncover the dark matter, they may need to reassess their understanding of what dark matter is. As Ghag suggests, future dark matter detectors may not be massive underground structures but rather smaller, unassuming devices. He has already devised a prototype of such a detector ahead of his upcoming talks at New Scientist Live this October.

Leah Crane: To start, why is dark matter so essential?

Chamkaur Ghag: On one side, we have all the knowledge that particles and atoms, alongside particle physics, provide about the components of matter. On the contrary, we understand gravity as well. While this may seem comprehensive, a significant issue arises when attempting to merge gravity and particle physics. Our galaxy shouldn’t exist as it does. It remains intact through gravity, which seems to derive from unseen matter. This isn’t just a tiny glue; around 85% of the universe comprises this so-called dark matter.

Why have our efforts to find it been so prolonged, with little success?

At present, we hypothesize that dark matter likely consists of what we term “wimps”—massive, weakly interacting particles that originated in the early universe. Consequently, these rarely interact with other particles, providing only a faint signature, which necessitates a large detector for detection. The larger these detectors are, the greater the chance that dark matter particles will pass through them. Additionally, they must be extremely quiet since even slight vibrations can obscure the signal.

We discuss the theoretical landscape of dark matter, which encompasses the range of masses and characteristics such particles could possess. We’ve already excluded certain regions of this landscape, making it essential to delve even deeper underground with larger detectors to explore where dark matter may still exist.

This painstaking endeavor requires minimizing background noise. For instance, many metals emit small radioactive levels, necessitating rigorous efforts to reduce construction material noise. The LZ detector boasts the lowest background noise and the highest level of radio-purity on the planet.

The LZ is currently the most sensitive detector we have. How does it function?

In essence, it operates as a double-walled thermos, containing several meters of liquid xenon. This xenon resides within a reflective tank, equipped with light sensors positioned above and below. Additionally, an electric field exists within this tank. When a wimp collides with a xenon nucleus, it generates a brief flash of light. However, due to the electric field, it causes the electrons to split apart, producing a second flash from the nucleus.

This two-signal output enables us to ascertain the exact location of an event. The intensity of both the primary and secondary flashes informs us about the microphysics of whether the interaction was caused by a wimp or an unrelated phenomenon, such as gamma rays. To ensure optimal detection, we are positioned miles underground to shield against cosmic rays and also encapsulated in an aquarium to safeguard against the surrounding rock.

This endeavor is undoubtedly complex. What has been the most challenging aspect of making it operational?

In an earlier experiment with a smaller prototype called Lux, I understood what was required to create an instrument tenfold more sensitive. Bringing that theoretical knowledge into practice proved challenging. For me, the toughest challenge lay in ensuring the instrument remained clean and quiet enough to achieve required sensitivity. When deployed with the LZ, it occupies a vast area equivalent to a football pitch, where it must tolerate only a gram of dust spread across its surface.

What is it like working with such an ultra-clean detector underground?

The environment, once a gold mine, retains its industrial atmosphere. You don a hard hat, descend a mile down, and then trek to the lab. Upon entering the lab, you lose sense of the surroundings; it transforms into a clean room filled with computers and equipment—essentially a lab devoid of windows. But the journey underground feels otherworldly.

Outer Detectors of the Lux-Zeplin Experiment

Sanford Underground Research Facility/Matthew Kapust

Historically, wimps have been the primary suspect for dark matter. At what point do we consider the wimp hypothesis invalid if we find no evidence?

Should we construct the XLZDs, the larger detectors intended for this purpose, and reach a point where they fail to detect wimps, it would be hard to sustain the idea of a standard wimp existing if we must venture beyond the capabilities of those instruments. However, until that happens, wimps are still in the game. The void between our current findings and those of the XLZD remains intriguing.

We’ve also developed a much smaller, entirely different detector for dark matter. Can you tell me more about it?

We’ve engineered 150 nanometer wide glass beads coated with lasers. This highly sensitive force detector can determine interactions in three dimensions, allowing us to ascertain which direction an event originated from. This capability is significant as it enables us to filter out terrestrial background influence, such as radioactive decay from geological materials.

This concept seems far removed from large detectors like the LZ. What’s the logic behind its creation? Will we see further advancements in smaller detectors?

Large-scale underground experiments, while large and sensitive, can paradoxically limit sensitivity due to their size. For instance, when a dark matter particle collides with my xenon detector, it may produce 10 photons. A smaller tank can capture all of them, but in a larger tank, these photons could bounce around and only a few are detected.

Furthermore, when a dark matter particle interacts with my detector, it only generates two photons initially. In this scenario, the maximal signal from a detector akin to the LZ diminishes. This has spurred the motivation to search for low-mass dark matter particles beyond the LZ’s detection range, leading us toward alternative detection methods.

If dark matter were to be discovered, what implications would that hold for physics and our understanding of the universe?

The implications would be two-fold: it would conclusively provide answers to what constitutes 85% of the universe, and it would challenge the standard model of particle physics, which currently outlines the known components of reality. Thus, if we discovered dark matter, it may offer the first glimpse beyond this conventional framework. Up until now, we’ve had no solid evidence to deviate from the standard model—this would serve as the first ray of hope.

Topics:

  • Dark Matter/
  • Particle Physics

Source: www.newscientist.com

Ganymede, Jupiter’s Moon, May Function as a Massive Dark Matter Detector

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View of Ganymede from NASA’s Juno spacecraft

junocam/nasa/jpl-caltech/swri/msss/kalleheikki kannisto

Ganymede, one of Jupiter’s moons, has the potential to act as a significant dark matter detector, with upcoming space missions possibly unveiling unique dark matter craters on its ancient terrain.

Researchers typically seek dark matter by looking for lightweight particles that seldom interact with normal matter, employing large, insulated underground detectors. Alternatively, another category of dark matter particles could grow from the size of a basketball to that of an asteroid, but these are infrequent and interact rarely with conventional matter. To detect these hefty dark matter particles, a detector of lunar or planetary scale is necessary to account for their scarcity.

William Derocco from the University of Maryland has proposed that Ganymede, the solar system’s largest moon, may hold clues to these large dark matter particles. His research indicates that they could create a unique crater on the moon’s icy surface, preserved for millions of years due to its stable geology.

Derocco estimates the extent to which these giant dark matter particles penetrate Ganymede’s thick ice layers, finding that they reach the subterranean oceans, fostering unique minerals deeper than a standard asteroid might.

Future missions, such as NASA’s Europa Clipper and ESA’s JUICE, might be able to identify these dark material craters from orbit. Derocco believes these features will be relatively small and distinct, separated from other geological formations. He suggests that “if an underground intrusion radar is used, it may reveal this melted ice column extending down through the ice.”

Utilizing a moon-sized dark matter detector could help identify particles that elude detection on Earth, according to Zachary Picker from UCLA. He states, “Experiments on Earth struggle to find dark matter particles the size of a bowling ball. Particles the size of a refrigerator or car have interactions that are too infrequent.”

The proposal is thorough and well-reasoned, as noted by Bradley Cabana from the University of Cantabria in Spain. “There’s no compelling physical rationale to assume the existence of such massive dark matter particles,” he states. “It’s about exploring all possibilities.” He describes these as extraordinary objects, incredibly dense and held together by formidable forces from obscure sectors.

Topics:

  • Dark matter/
  • Space exploration

Source: www.newscientist.com

Vapor-Sensing Drug Detector Tested at the US-Mexico Border

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The vapor detector has the ability to detect traces of fentanyl and other substances in the air.

Elizabeth Dennis/Pacific Northwest National Laboratory

The U.S. Customs and Border Protection Agency is currently evaluating technology that can detect illegal substances in the air without any physical contact. This device aims to screen border items within seconds, targeting the trafficking of drugs like fentanyl, which is a major factor in the U.S. opioid crisis.

Detecting drugs and explosive materials is challenging due to the limited number of molecules they release into the air, which is already crowded with various vapors. To tackle this issue, Robert Ewing and his team at the Pacific Northwest National Laboratory (PNNL) have dedicated over a decade to developing an advanced system known as VaporID. This system can accurately identify certain substances within a range of 0.6 to 2.4 meters at an astonishing sensitivity, comparable to locating a single coin amidst 17 million stacked pennies equivalent to the height of Mount Everest.

Government researchers achieved this by allowing molecules to interact longer, increasing the chances of detectable chemical reactions. Most devices for detecting unknown substances only provide a reaction time of milliseconds, Ewing stated. “We designed an atmospheric flow tube that allows for a reaction time of 2-3 seconds, enhancing sensitivity by three orders of magnitude.”

The technology is currently implemented in an 18-kilogram commercial device that fits in the size of a microwave. This compact machine, developed by Bayspec, is indeed lighter than their previous versions, which weighed over 100 kilograms but were less sensitive than the PNNL prototype, which is about the size of a small fridge. Nevertheless, it claims to be “more accurate and sensitive than a canine detector,” according to William Yang, CEO of Bayspec.

In October 2024, Bayspec and PNNL tested the portable device at a Customs and Border Protection facility in Nogales, Arizona. In separate trials, researchers swabbed the surfaces of seized tablets and then heated the swabs to generate steam for detection. “Both methods yielded strong and reliable results,” stated Christian Thoma from Bayspec.

The prototype is still under evaluation and requires further scientific data review, as noted by a spokesperson from CBP.

Alex Krotulski from the Center for Forensic Research and Education, a nonprofit based in Pennsylvania, expressed caution, stating, “We have seen numerous devices that have promised much but have often disappointed, and we remain skeptical until thorough research proves their efficacy.”

Current portable detection techniques, including x-ray technology, already exist for uncovering concealed drugs. Independent consultant Richard Crocombe acknowledged the new tool as a “valuable addition to existing techniques,” but cautioned that it “doesn’t fulfill every requirement.” For instance, a CBP representative mentioned that while the device could expedite drug testing in field labs, new innovations would necessitate analysis by trained chemists.

Concerns about false positives are also prevalent, as noted by Joseph Palamar at New York University. A past study indicated that a majority of U.S. banknotes carry contamination. “If you are near someone using fentanyl, a positive result can occur due to residual traces on their clothing or shoes, leading to potential wrongful detainment of innocent individuals,” he added, as explained by Chelsea Schauber from UCLA.

Intercepting drugs before they reach the country is merely one component of a comprehensive strategy required to tackle the opioid crisis, says Schauber. This broader effort demands robust public health resources, healthcare access, and extensive treatment alternatives. “Currently, these supports are being reduced under the Trump administration,” she noted. “To genuinely save lives, we need to make effective, evidence-based treatments more accessible than illicit substances,” Schober emphasized.

topic:

Source: www.newscientist.com

Surprising discovery: AMS detector detects a higher-than-expected number of cosmic rays containing deuterons

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Deuteron It is believed that atomic nuclei consisting of protons and neutrons, like those of helium-3 nuclei, are formed in collisions between helium-4 nuclei and other nuclei in the interstellar medium. If this were the case, the flux ratio of deuterons to helium-4 should be similar to that of helium-3 to helium-4. However, this is not the case. Alpha Magnetic Spectrometer Astronauts aboard the International Space Station (AMS) are watching.

Aguilar othersThe deuteron flux was measured using the Alpha Magnetic Spectrometer (AMS) on board the International Space Station.

Cosmic rays are high-energy particles with energies ranging from MeV to 10.20 Electronic V.

These properties are studied from measurements of the energy (stiffness) spectrum (number of particles per unit time, solid angle, surface area, and energy as a function of energy), which is characterized by a rapid decrease in the spectrum as the energy increases.

Cosmic rays with energies below PeV are thought to originate in our own Milky Way galaxy.

The elemental composition of these galactic cosmic rays is dominated by hydrogen nuclei, primarily protons, with helium nuclei making up about 10%, and electrons and nuclei heavier than helium making up just 1% each.

The species synthesized in stars, such as protons, electrons, and most atomic nuclei, are called primary cosmic rays.

Light nuclei, synthesized by nuclear fusion in the cores of stars, are more abundant than heavy nuclei because their production becomes energetically unfavorable as mass increases.

The synthesis of atomic nuclei heavier than iron, such as nickel, occurs through explosive phenomena such as supernova explosions that occur at the end of the life of massive stars, so atomic nuclei heavier than iron are extremely rare.

When primary nuclei are ejected from their source in space, they can collide with interstellar material and split into lighter species.

This is the primary production mechanism for atomic nuclei that are energetically unfavorable to produce by stellar nucleosynthesis, such as lithium, beryllium, boron, fluorine, scandium, titanium, and vanadium. These are called secondary cosmic rays.

Compared to primary nuclei of similar mass, secondary nuclei are less abundant and, as stiffness increases, their stiffness spectrum decreases faster than that of primary nuclei.

The energy (or rigidity) dependence of the cosmic ray spectrum arises from a combination of source-directed emission, acceleration, and propagation mechanisms that occur during a cosmic ray's passage through the galaxy.

Cosmic rays are diffusely accelerated by expanding shock waves, propagate diffusely through the interstellar medium, and are scattered by irregularities in the galactic magnetic field, both of which depend on the particle's momentum, and thus on its magnetic stiffness.

Cosmic ray propagation is described by a stiffness-dependent diffusion coefficient that incorporates the properties of turbulence in the galactic magnetic field.

“Hydrogen nuclei are the most abundant species of cosmic ray,” members of the AMS collaboration wrote in the paper.

“They are made up of two stable isotopes: protons and deuterons.”

“Big Bang nucleosynthesis predicts negligible production of deuterium, and over time the abundance of deuterons has decreased from its primordial value, with the ratio of deuterons to protons measured in the interstellar medium being 0.00002.”

“Deuterons are thought to arise primarily from the interaction of helium with interstellar matter, rather than being accelerated in supernova remnants like primary cosmic ray protons and helium-4.”

“Deuterons, along with helium-3, are called secondary cosmic rays.”

For the latest study, AMS physicists examined data from 21 million cosmic deuterons detected by AMS between May 2011 and April 2021.

When investigating how the deuteron flux varies with rigidity, a surprising feature was discovered.

The AMS data show that these ratios differ significantly above a stiffness of 4.5 GV, with the deuteron to helium-4 ratio decreasing more slowly with stiffness than the helium-3 to helium-4 ratio.

Furthermore, and again contrary to expectations, when stiffness exceeds 13 GV, the data show that the flux of deuterons is nearly the same as the flux of protons, the primary cosmic ray.

Simply put, researchers found more deuterons than expected from collisions between main helium-4 nuclei and interstellar matter.

“Measuring deuterons is very challenging due to the large cosmic proton background radiation,” said Dr Samuel Ting, spokesman for the AMS collaboration.

“Our unexpected results show how little we know about cosmic rays.”

“Future upgrades to AMS will increase the acceptance rate by 300 percent, enabling AMS to measure all charged cosmic rays with 1 percent accuracy, providing the experimental basis for the development of accurate cosmic ray theory.”

The team's paper was published in the journal Physics Review Letter.

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M. Aguilar others(AMS Collaboration). 2024. Properties of cosmic deuterons measured with the Alpha Magnetic Spectrometer. Physiotherapy Rev Lett 132(26):261001;doi:10.1103/PhysRevLett.132.261001

Source: www.sci.news