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127-611: CAST is currently the most sensitive axion helioscope. If the axions exist, they may be produced in the Sun's core when X-rays scatter off electrons and protons in the presence of strong electric fields . The experimental setup is built around a 9.26 m long decommissioned test magnet for the LHC capable of producing a field of up to 9.5  T . This strong magnetic field is expected to convert solar axions back into X-rays for subsequent detection by X-ray detectors. The telescope observes

254-536: A γ {\displaystyle g_{a\gamma }} (parameter for axion-photon coupling) with a 95% confidence limit (CL) for axion mass- m a ≲ 0.02 e V {\displaystyle \mathrm {m_{a}\lesssim 0.02eV} } . For axion mass range between 34.6771 μ e V {\displaystyle \mathrm {34.6771\mu eV} } and 34.6738 μ e V {\displaystyle \mathrm {34.6738\mu eV} } , RADES constrained

381-456: A Ruhmkorff coil connected to a cold cathode Crookes X-ray tube . A spark gap was typically connected to the high voltage side in parallel to the tube and used for diagnostic purposes. The spark gap allowed detecting the polarity of the sparks, measuring voltage by the length of the sparks thus determining the "hardness" of the vacuum of the tube, and it provided a load in the event the X-ray tube

508-470: A Weyl semimetal material. In the axion insulator phase, the material has an axion-like quasiparticle – an excitation of electrons that behave together as an axion – and its discovery demonstrates the consistency of axion electrodynamics as a description of the interaction of axion-like particles with electromagnetic fields. In this way, the discovery of axion-like quasiparticles in axion insulators provides motivation to use axion electrodynamics to search for

635-524: A paper to the Royal Society of London describing the effects of passing electrical currents through a partially evacuated glass tube, producing a glow created by X-rays. This work was further explored by Humphry Davy and his assistant Michael Faraday . Starting in 1888, Philipp Lenard conducted experiments to see whether cathode rays could pass out of the Crookes tube into the air. He built

762-613: A wavelength ranging from 10  nanometers to 10  picometers , corresponding to frequencies in the range of 30  petahertz to 30  exahertz ( 3 × 10  Hz to 3 × 10  Hz ) and photon energies in the range of 100  eV to 100  keV , respectively. X-rays were discovered in 1895 by the German scientist Wilhelm Conrad Röntgen , who named it X-radiation to signify an unknown type of radiation. X-rays can penetrate many solid substances such as construction materials and living tissue, so X-ray radiography

889-458: A 225-day run to set the best coupling limits to date and exclude some parameters. While Schiff's theorem states that a static nuclear electric dipole moment (EDM) does not produce atomic and molecular EDMs, the axion induces an oscillating nuclear EDM that oscillates at the Larmor frequency . If this nuclear EDM oscillation frequency is in resonance with an external electric field, a precession in

1016-486: A Crookes tube with a "window" at the end made of thin aluminium, facing the cathode so the cathode rays would strike it (later called a "Lenard tube"). He found that something came through, that would expose photographic plates and cause fluorescence. He measured the penetrating power of these rays through various materials. It has been suggested that at least some of these "Lenard rays" were actually X-rays. Helmholtz formulated mathematical equations for X-rays. He postulated

1143-673: A cancer (then called X-ray dermatitis) sufficiently advanced by 1904 to cause him to write papers and give public addresses on the dangers of X-rays. His left arm had to be amputated at the elbow in 1908, and four fingers on his right arm soon thereafter, leaving only a thumb. He died of cancer in 1926. His left hand is kept at Birmingham University . The many applications of X-rays immediately generated enormous interest. Workshops began making specialized versions of Crookes tubes for generating X-rays and these first-generation cold cathode or Crookes X-ray tubes were used until about 1920. A typical early 20th-century medical X-ray system consisted of

1270-598: A characteristic X-ray spectrum . He won the 1917 Nobel Prize in Physics for this discovery. In 1912 , Max von Laue , Paul Knipping, and Walter Friedrich first observed the diffraction of X-rays by crystals. This discovery, along with the early work of Paul Peter Ewald , William Henry Bragg , and William Lawrence Bragg , gave birth to the field of X-ray crystallography . In 1913 , Henry Moseley performed crystallography experiments with X-rays emanating from various metals and formulated Moseley's law which relates

1397-564: A couple of minutes for a thorax. The plates may have a small addition of fluorescent salt to reduce exposure times. Crookes tubes were unreliable. They had to contain a small quantity of gas (invariably air) as a current will not flow in such a tube if they are fully evacuated. However, as time passed, the X-rays caused the glass to absorb the gas, causing the tube to generate "harder" X-rays until it soon stopped operating. Larger and more frequently used tubes were provided with devices for restoring

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1524-489: A dispersion theory before Röntgen made his discovery and announcement. He based it on the electromagnetic theory of light . However, he did not work with actual X-rays. In early 1890, photographer William Jennings and associate professor of the University of Pennsylvania Arthur W. Goodspeed were making photographs of coins with electric sparks. On 22nd February after the end of their experiments two coins were left on

1651-413: A flash of light from a fluorescent screen immediately before the covered tube he was switching on punctured. When Stanford University physics professor Fernando Sanford conducted his "electric photography" experiments in 1891-1893 by photographing coins in the light of electric sparks, like Jennings and Goodspeed, he may have unknowingly generated and detected X-rays. His letter of 6 January 1893 to

1778-610: A foreword by Boulenger, was published in 1897. The first medical X-ray made in the United States was obtained using a discharge tube of Ivan Puluj 's design. In January 1896, on reading of Röntgen's discovery, Frank Austin of Dartmouth College tested all of the discharge tubes in the physics laboratory and found that only the Puluj tube produced X-rays. This was a result of Puluj's inclusion of an oblique "target" of mica , used for holding samples of fluorescent material, within

1905-447: A futile attempt to save his life; in 1904, he became the first known death attributed to X-ray exposure. During the time the fluoroscope was being developed, Serbian American physicist Mihajlo Pupin , using a calcium tungstate screen developed by Edison, found that using a fluorescent screen decreased the exposure time it took to create an X-ray for medical imaging from an hour to a few minutes. In 1901, U.S. President William McKinley

2032-492: A graduate of Columbia College, suffered severe hand and chest burns from an X-ray demonstration. It was reported in Electrical Review and led to many other reports of problems associated with X-rays being sent in to the publication. Many experimenters including Elihu Thomson at Edison's lab, William J. Morton , and Nikola Tesla also reported burns. Elihu Thomson deliberately exposed a finger to an X-ray tube over

2159-649: A hand). Through February, there were 46 experimenters taking up the technique in North America alone. The first use of X-rays under clinical conditions was by John Hall-Edwards in Birmingham, England on 11 January 1896, when he radiographed a needle stuck in the hand of an associate. On 14 February 1896, Hall-Edwards was also the first to use X-rays in a surgical operation. In early 1896, several weeks after Röntgen's discovery, Ivan Romanovich Tarkhanov irradiated frogs and insects with X-rays, concluding that

2286-448: A large electric dipole moment (EDM) for the neutron . Experimental constraints on the unobserved EDM implies CP violation from QCD must be extremely tiny and thus Θ must itself be extremely small. Since Θ could have any value between 0 and 2 π , this presents a "naturalness" problem for the standard model. Why should this parameter find itself so close to zero? (Or, why should QCD find itself CP-preserving?) This question constitutes what

2413-462: A magnetic field. The concept was first put forward in 1986 by Luciano Maiani , Roberto Petronzio and Emilio Zavattini . A rotation claim in 2006 was excluded by an upgraded setup. An optimized search began in 2014. Another technique is so called "light shining through walls", where light passes through an intense magnetic field to convert photons into axions, which then pass through metal and are reconstituted as photons by another magnetic field on

2540-507: A new kind of ray: A preliminary communication" and on 28 December 1895, submitted it to Würzburg 's Physical-Medical Society journal. This was the first paper written on X-rays. Röntgen referred to the radiation as "X", to indicate that it was an unknown type of radiation. Some early texts refer to them as Chi-rays, having interpreted "X" as the uppercase Greek letter Chi , Χ . There are conflicting accounts of his discovery because Röntgen had his lab notes burned after his death, but this

2667-499: A period of time and suffered pain, swelling, and blistering. Other effects were sometimes blamed for the damage including ultraviolet rays and (according to Tesla) ozone. Many physicians claimed there were no effects from X-ray exposure at all. On 3 August 1905, in San Francisco, California, Elizabeth Fleischman , an American X-ray pioneer, died from complications as a result of her work with X-rays. Hall-Edwards developed

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2794-411: A possible origin for both phenomena. In 2022 a similar hypothesis was used to constrain the mass of the axion from data of M87*. In 2020, it was proposed that the axion field might actually have influenced the evolution of the early Universe by creating more imbalance between the amounts of matter and antimatter – which possibly resolves the baryon asymmetry problem. In supersymmetric theories

2921-457: A screen coated with barium platinocyanide . On 5 February 1896, live imaging devices were developed by both Italian scientist Enrico Salvioni (his "cryptoscope") and William Francis Magie of Princeton University (his "Skiascope"), both using barium platinocyanide. American inventor Thomas Edison started research soon after Röntgen's discovery and investigated materials' ability to fluoresce when exposed to X-rays, finding that calcium tungstate

3048-448: A set of equations that imposed duality symmetry, assuming the existence of magnetic monopoles . However, these alternative formulations are less theoretically motivated, and in many cases cannot even be derived from an action . A term analogous to the one that would be added to Maxwell's equations to account for axions also appears in recent (2008) theoretical models for topological insulators giving an effective axion description of

3175-474: A solution to the apparent transparency of the Universe to TeV photons. It has also been demonstrated that, in the large magnetic fields threading the atmospheres of compact astrophysical objects (e.g., magnetars ), photons will convert much more efficiently. This would in turn give rise to distinct absorption-like features in the spectra detectable by early 21st century telescopes. A new (2009) promising means

3302-420: A stack of photographic plates before Goodspeed demonstrated to Jennings the operation of Crookes tubes . While developing the plates, Jennings noticed disks of unknown origin on some of the plates, but nobody could explain them, and they moved on. Only in 1896 they realized that they accidentally made an X-ray photograph (they didn't claim a discovery). Also in 1890, Roentgen's assistant Ludwig Zehnder noticed

3429-438: A theoretical team from Massachusetts Institute of Technology devised a possible way of detecting axions using a strong magnetic field that need be no stronger than that produced in an MRI scanning machine. It would show variation, a slight wavering, that is linked to the mass of the axion. Results from the ensuing experiment published in 2021 reported no evidence of axions in the mass range from 4.1x10 to 8.27x10 eV. In 2022

3556-464: A variety of techniques that use phase information of an X-ray beam to form the image. Due to its good sensitivity to density differences, it is especially useful for imaging soft tissues. It has become an important method for visualizing cellular and histological structures in a wide range of biological and medical studies. There are several technologies being used for X-ray phase-contrast imaging, all using different principles to convert phase variations in

3683-458: Is 76 mm. The overall mirror system has a focal length of 1.6 m. This detector achieved a remarkably good signal to noise ratio by focusing the axions created inside the magnetic field chamber onto small, about few m m 2 {\displaystyle mm^{2}} area. In 2016, The GridPix detector was installed to detect the soft X-rays (energy range of 200 eV to 10 KeV) generated by solar chameleons through

3810-422: Is a gas-filled drift chambers type of detector, designed to detect the low-intensity X-ray signals at CAST. The interactions in this detector take place in a very large gaseous chamber and produce ionizing electrons. These electrons travel towards the multiwire proportional chamber (MWPC), where the signal is then amplified through the avalanche process. This detector operated during the period of 2002 to 2004. It

3937-404: Is a gaseous detector and was primarily employed for to detect X-rays in the energy range of 1–10 KeV. The detector itself was made up of low radioactive materials. The choice of material was mainly based on reducing the background noise, and Micromegas achieved a significantly low background rejection of 6 × 10 counts·keV·cm·s without any shielding. This detector has a pn-CCD chip located at

CERN Axion Solar Telescope - Misplaced Pages Continue

4064-516: Is a hypothetical elementary particle originally theorized in 1978 independently by Frank Wilczek and Steven Weinberg as the Goldstone boson of Peccei–Quinn theory , which had been proposed in 1977 to solve the strong CP problem in quantum chromodynamics (QCD). If axions exist and have low mass within a specific range, they are of interest as a possible component of cold dark matter . As shown by Gerard 't Hooft , strong interactions of

4191-611: Is a kind of scalar field dark matter that seems to solve the small scale problems of CDM. A single ULA with a GUT scale decay constant provides the correct relic density without fine-tuning. Axions would also have stopped interaction with normal matter at a different moment after the Big Bang than other more massive dark particles. The lingering effects of this difference could perhaps be calculated and observed astronomically. If axions have low mass, thus preventing other decay modes (since there are no lighter particles to decay into),

4318-405: Is a likely reconstruction by his biographers: Röntgen was investigating cathode rays from a Crookes tube which he had wrapped in black cardboard so that the visible light from the tube would not interfere, using a fluorescent screen painted with barium platinocyanide . He noticed a faint green glow from the screen, about 1 meter (3.3 ft) away. Röntgen realized some invisible rays coming from

4445-459: Is also sensitive to dark matter axion tidal or cosmological streams and to the theorized axion mini-clusters. A newer and better version of CAPP is being developed at CAPP, South Korea. The CAST experiment began with the goal of devising new methods and implementing novel technologies for the detection of solar axions. Owing to the inter-disciplinary and interrelated field of axion studies, dark matter , dark energy , and axion-like exotic particles,

4572-482: Is designed to detect the coupling of solar chameleons with matter particles. It uses a very sensitive optomechanical force sensor, capable of detecting a displacement in a thin membrane caused by the mechanical effects from the solar chameleon interactions. This detector has a delicate tuning mechanism, made of 2 parallel sapphire plates and activated by a piezoelectric motor . The maximum tuning corresponds to axions masses between 21–23 μeV. CAST-CAPP detector

4699-412: Is generally greatly outweighed by the benefits of the examination. The ionizing capability of X-rays can be used in cancer treatment to kill malignant cells using radiation therapy . It is also used for material characterization using X-ray spectroscopy . Hard X-rays can traverse relatively thick objects without being much absorbed or scattered . For this reason, X-rays are widely used to image

4826-457: Is higher. The high amount of calcium ( Z = 20 {\textstyle Z=20} ) in bones, together with their high density, is what makes them show up so clearly on medical radiographs. A photoabsorbed photon transfers all its energy to the electron with which it interacts, thus ionizing the atom to which the electron was bound and producing a photoelectron that is likely to ionize more atoms in its path. An outer electron will fill

4953-517: Is known as the strong CP problem . In 1977, Roberto Peccei and Helen Quinn postulated a more elegant solution to the strong CP problem, the Peccei–Quinn mechanism . The idea is to effectively promote Θ to a field. This is accomplished by adding a new global symmetry (called a Peccei–Quinn (PQ) symmetry ) that becomes spontaneously broken. This results in a new particle, as shown independently by Frank Wilczek and Steven Weinberg , that fills

5080-401: Is looking for quasi-particle refraction in systems with strong magnetic gradients. In particular, the refraction will lead to beam splitting in the radio light curves of highly magnetized pulsars and allow much greater sensitivities than currently achievable. The International Axion Observatory (IAXO) is a proposed fourth generation helioscope . Axions can resonantly convert into photons in

5207-571: Is now under preparation. The CAST focuses on the solar axions using a helioscope , which is a 9.2 m superconducting LHC prototype dipole magnet. The superconductive magnet is maintained by constantly keeping it at 1.8 Kelvin using superfluid helium . There are two magnetic bores of 43 mm diameter and 9.2 6m length with X-ray detectors placed at all ends. These detectors are sensitive to photons from inverse Primakoff conversion of solar axions. The two X-ray telescopes of CAST measures both signal and background simultaneously with

CERN Axion Solar Telescope - Misplaced Pages Continue

5334-535: Is often referred to as tender X-rays . Due to their penetrating ability, hard X-rays are widely used to image the inside of objects (e.g. in medical radiography and airport security ). The term X-ray is metonymically used to refer to a radiographic image produced using this method, in addition to the method itself. Since the wavelengths of hard X-rays are similar to the size of atoms, they are also useful for determining crystal structures by X-ray crystallography . By contrast, soft X-rays are easily absorbed in air;

5461-492: Is strictly controlled by public health authorities. X-rays were originally noticed in science as a type of unidentified radiation emanating from discharge tubes by experimenters investigating cathode rays produced by such tubes, which are energetic electron beams that were first observed in 1869. Early researchers noticed effects that were attributable to them in many of the early Crookes tubes (invented around 1875 ). Crookes tubes created free electrons by ionization of

5588-451: Is the dominant interaction mechanism in the soft X-ray regime and for the lower hard X-ray energies. At higher energies, Compton scattering dominates. The probability of a photoelectric absorption per unit mass is approximately proportional to Z 3 / E 3 {\textstyle Z^{3}/E^{3}} , where Z {\textstyle Z} is the atomic number and E {\textstyle E}

5715-524: Is the energy of the incident photon. This rule is not valid close to inner shell electron binding energies where there are abrupt changes in interaction probability, so called absorption edges . However, the general trend of high absorption coefficients and thus short penetration depths for low photon energies and high atomic numbers is very strong. For soft tissue, photoabsorption dominates up to about 26 keV photon energy where Compton scattering takes over. For higher atomic number substances, this limit

5842-401: Is widely used in medical diagnostics (e.g., checking for broken bones ) and material science (e.g., identification of some chemical elements and detecting weak points in construction materials). However X-rays are ionizing radiation and exposure can be hazardous to health, causing DNA damage, cancer and, at higher intensities, burns and radiation sickness . Their generation and use

5969-915: The Physical Review was duly published and an article entitled Without Lens or Light, Photographs Taken With Plate and Object in Darkness appeared in the San Francisco Examiner . In 1894 , Nikola Tesla noticed damaged film in his lab that seemed to be associated with Crookes tube experiments and began investigating this invisible, radiant energy . After Röntgen identified the X-ray, Tesla began making X-ray images of his own using high voltages and tubes of his own design, as well as Crookes tubes. On 8 November 1895 , German physics professor Wilhelm Röntgen stumbled on X-rays while experimenting with Lenard tubes and Crookes tubes and began studying them. He wrote an initial report "On

6096-770: The CERN Axion Solar Telescope converts axions produced in the Sun's core to X-rays, and other experiments search for axions produced in laser light. As of the early 2020s, there are dozens of proposed or ongoing experiments searching for axion dark matter. The equations of axion electrodynamics are typically written in "natural units", where the reduced Planck constant ℏ {\displaystyle \hbar } , speed of light c {\displaystyle c} , and permittivity of free space ε 0 {\displaystyle \varepsilon _{0}} all reduce to 1 when expressed in these "natural units". In this unit system,

6223-581: The Peccei-Quinn mechanism for solving the strong CP problem required such large couplings. However, it was soon realized that "invisible axions" with much smaller couplings also work. Two such classes of models are known in the literature as KSVZ ( Kim – Shifman – Vainshtein – Zakharov ) and DFSZ ( Dine – Fischler – Srednicki – Zhitnitsky ). The very weakly coupled axion is also very light, because axion couplings and mass are proportional. Satisfaction with "invisible axions" changed when it

6350-470: The Primakoff effect , which converts axions to photons and vice versa in electromagnetic fields. The Axion Dark Matter Experiment (ADMX) at the University of Washington uses a strong magnetic field to detect the possible weak conversion of axions to microwaves . ADMX searches the galactic dark matter halo for axions resonant with a cold microwave cavity. ADMX has excluded optimistic axion models in

6477-550: The Reagan Administration 's Strategic Defense Initiative in the 1980s, but the only test of the device (a sort of laser "blaster" or death ray , powered by a thermonuclear explosion) gave inconclusive results. For technical and political reasons, the overall project (including the X-ray laser) was defunded (though was later revived by the second Bush Administration as National Missile Defense using different technologies). Phase-contrast X-ray imaging refers to

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6604-640: The XENON1T experiment at the Gran Sasso National Laboratory in Italy reported a result suggesting the discovery of solar axions. The results were not significant at the 5-sigma level required for confirmation, and other explanations of the data were possible though less likely. New observations made in July 2022 after the observatory upgrade to XENONnT discarded the excess, thus ending

6731-493: The attenuation length of 600 eV (~2 nm) X-rays in water is less than 1 micrometer. There is no consensus for a definition distinguishing between X-rays and gamma rays . One common practice is to distinguish between the two types of radiation based on their source: X-rays are emitted by electrons , while gamma rays are emitted by the atomic nucleus . This definition has several problems: other processes can also generate these high-energy photons , or sometimes

6858-518: The light-by-light scattering process. Those searches are sensitive for rather large axion masses between 100 MeV/c and hundreds of GeV/c . Assuming a coupling of axions to the Higgs boson, searches for anomalous Higgs boson decays into two axions can theoretically provide even stronger limits. It was reported in 2014 that evidence for axions may have been detected as a seasonal variation in observed X-ray emission that would be expected from conversion in

6985-647: The magnetospheres of neutron stars . The emerging photons lie in the GHz frequency range and can be potentially picked up in radio detectors, leading to a sensitive probe of the axion parameter space. This strategy has been used to constrain the axion–photon coupling in the 5–11 μeV mass range, by re-analyzing existing data from the Green Bank Telescope and the Effelsberg 100 m Radio Telescope . A novel, alternative strategy consists in detecting

7112-662: The solar chameleons and pharaphotons as well as the relic axions from the Big bang and Inflation . In late 2017, the CAST helioscope which originally was searching for solar axion and ALPs, was converted into haloscope to hunt for the Dark Matter wind in milky way 's galactic halo while it crosses the Earth. These idea of streaming dark wind is thought to affect and cause the random and anisotropic orientation of solar flares , for which

7239-444: The thermionic diode , the first kind of vacuum tube . This used a hot cathode that caused an electric current to flow in a vacuum . This idea was quickly applied to X-ray tubes, and hence heated-cathode X-ray tubes, called "Coolidge tubes", completely replaced the troublesome cold cathode tubes by about 1920. In about 1906, the physicist Charles Barkla discovered that X-rays could be scattered by gases, and that each element had

7366-538: The 1.9–3.53 μeV range. From 2013 to 2018 a series of upgrades were done and it is taking new data, including at 4.9–6.2 μeV. In December 2021 it excluded the 3.3–4.2 μeV range for the KSVZ model. Other experiments of this type include DMRadio, HAYSTAC, CULTASK, and ORGAN. HAYSTAC completed the first scanning run of a haloscope above 20 μeV in the late 2010s. The Italian PVLAS experiment searches for polarization changes of light propagating in

7493-469: The CAST haloscope will serve as a testbed. In the dark energy domain CAST is currently looking for signatures of a chameleon, which is hypothesized to be a particle produced when dark energy interacts with the photons. This area is currently in its beginning stages, wherein possible ways of dark energy particles coupling with normal matter are being theorized. Using the GridPix detector, the upper bound on

7620-511: The Earth's magnetic field of axions streaming from the Sun. Studying 15 years of data by the European Space Agency 's XMM-Newton observatory, a research group at Leicester University noticed a seasonal variation for which no conventional explanation could be found. One potential explanation for the variation, described as "plausible" by the senior author of the paper, is the known seasonal variation in visibility to XMM-Newton of

7747-487: The PQ field randomise the axion field, with no preferred value in the power spectrum. The proper treatment in this scenario is to solve numerically the equation of motion of the PQ field in an expanding Universe, in order to capture all features coming from the misalignment mechanism, including the contribution from topological defects like "axionic" strings and domain walls . An axion mass estimate between 0.05 and 1.50 meV

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7874-636: The Sun for about 1.5 hours at sunrise and another 1.5 hours at sunset each day. The remaining 21 hours, with the instrument pointing away from the Sun, are spent measuring background axion levels. CAST began operation in 2003 searching for axions up to 0.02  eV . In 2005, Helium-4 was added to the magnet, extending sensitivity to masses up to 0.39 eV, then Helium-3 was used during 2008–2011 for masses up to 1.15 eV. CAST then ran with vacuum again searching for axions below 0.02 eV. As of 2014, CAST has not turned up definitive evidence for solar axions. It has considerably narrowed down

8001-815: The X-rays emerging from an object into intensity variations. These include propagation-based phase contrast, Talbot interferometry, refraction-enhanced imaging, and X-ray interferometry. These methods provide higher contrast compared to normal absorption-based X-ray imaging, making it possible to distinguish from each other details that have almost similar density. A disadvantage is that these methods require more sophisticated equipment, such as synchrotron or microfocus X-ray sources, X-ray optics , and high resolution X-ray detectors. X-rays with high photon energies above 5–10 keV (below 0.2–0.1 nm wavelength) are called hard X-rays , while those with lower energy (and longer wavelength) are called soft X-rays . The intermediate range with photon energies of several keV

8128-458: The air, known as "softeners". These often took the form of a small side tube that contained a small piece of mica , a mineral that traps relatively large quantities of air within its structure. A small electrical heater heated the mica, causing it to release a small amount of air, thus restoring the tube's efficiency. However, the mica had a limited life, and the restoration process was difficult to control. In 1904 , John Ambrose Fleming invented

8255-474: The application so as to give sufficient transmission through the object and at the same time provide good contrast in the image. X-rays have much shorter wavelengths than visible light, which makes it possible to probe structures much smaller than can be seen using a normal microscope . This property is used in X-ray microscopy to acquire high-resolution images, and also in X-ray crystallography to determine

8382-465: The axion energy density. However, other bounds that come from isocurvature modes severely constrain this scenario, which require a relatively low-energy scale of inflation to be viable. If at least one of the conditions (a) or (b) is violated, the axion field takes different values within patches that are initially out of causal contact , but that today populate the volume enclosed by our Hubble horizon . In this scenario, isocurvature fluctuations in

8509-503: The axion field begins its evolution, depending on the following two conditions: Broadly speaking, one of the two possible scenarios outlined in the two following subsections occurs: If both (a) and (b) are satisfied, cosmic inflation selects one patch of the Universe within which the spontaneous breaking of the PQ symmetry leads to a homogeneous value of the initial value of the axion field. In this "pre-inflationary" scenario, topological defects are inflated away and do not contribute to

8636-460: The axion field moves. Expanding the potential about one of its minima, one finds that the product of the axion mass with the axion decay constant is determined by the topological susceptibility of the QCD vacuum. An axion with mass much less than 60 keV is long-lived and weakly interacting: A perfect dark matter candidate. The oscillations of the axion field about the minimum of the effective potential,

8763-494: The axion has both a scalar and a fermionic superpartner . The fermionic superpartner of the axion is called the axino , the scalar superpartner is called the saxion or dilaton . They are all bundled in a chiral superfield . Soft X-rays An X-ray (also known in many languages as Röntgen radiation ) is a form of high-energy electromagnetic radiation with a wavelength shorter than those of ultraviolet rays and longer than those of gamma rays . Roughly, X-rays have

8890-557: The axion itself. Despite not yet having been found, the axion has been well studied for over 40 years, giving time for physicists to develop insight into axion effects that might be detected. Several experimental searches for axions are presently underway; most exploit axions' expected slight interaction with photons in strong magnetic fields. Axions are also one of the few remaining plausible candidates for dark matter particles, and might be discovered in some dark matter experiments. Several experiments search for astrophysical axions by

9017-552: The axion mass to be placed from observations of neutron stars in gamma-rays using the Fermi Gamma-ray Space Telescope . From an analysis of four neutron stars, Berenji et al. (2016) obtained a 95% confidence interval upper limit on the axion mass of 0.079 eV. In 2021 it has been also suggested that a reported excess of hard X-ray emission from a system of neutron stars known as the magnificent seven could be explained as axion emission. In 2016,

9144-543: The axion, such as the axion mass, decay constant, and abundance, all have implications for cosmology. Inflation theory suggests that if they exist, axions would be created abundantly during the Big Bang . Because of a unique coupling to the instanton field of the primordial universe (the " misalignment mechanism "), an effective dynamical friction is created during the acquisition of mass, following cosmic inflation . This robs all such primordial axions of their kinetic energy. Ultralight axion (ULA) with m ~ 10 eV/ c

9271-703: The axion-photon coupling constant g a γ ≳ 4 × 10 − 13 G e V − 1 {\displaystyle \mathrm {g_{a\gamma }\gtrsim 4\times 10^{-13}GeV^{-1}} } with just about 5% error. The most recent results, in 2017 set an upper limit on g a γ {\displaystyle g_{a\gamma }} < 0.66 × 10 − 10 G e V − 1 {\displaystyle \mathrm {<0.66\times 10^{-10}GeV^{-1}} } (with 95% CL) for all axions with masses below 0.02 eV. CAST has thus improved

9398-505: The chameleon photon coupling constant- β γ {\displaystyle \beta _{\gamma }} was determined to be equal to 5.74 × 10 10 {\displaystyle 5.74\times 10^{10}} for β m {\displaystyle \beta _{m}} (chameleon matter coupling constant) in the range of 1 to 10 6 {\displaystyle 10^{6}} . KWISP detector obtained an upper limit on

9525-435: The early 1920s through to the 1950s, X-ray machines were developed to assist in the fitting of shoes and were sold to commercial shoe stores. Concerns regarding the impact of frequent or poorly controlled use were expressed in the 1950s, leading to the practice's eventual end that decade. The X-ray microscope was developed during the 1950s. The Chandra X-ray Observatory , launched on 23 July 1999 , has been allowing

9652-507: The electrodynamic equations are: Above, a dot above a variable denotes its time derivative; the dot spaced between variables is the vector dot product ; the factor   g a γ γ   {\displaystyle \ g_{a\gamma \gamma }\ } is the axion-to-photon coupling constant rendered in "natural units". Alternative forms of these equations have been proposed, which imply completely different physical signatures. For example, Visinelli wrote

9779-689: The electrodynamics of these materials. This term leads to several interesting predicted properties including a quantized magnetoelectric effect . Evidence for this effect has been given in THz spectroscopy experiments performed at the Johns Hopkins University on quantum regime thin film topological insulators developed at Rutgers University . In 2019, a team at the Max Planck Institute for Chemical Physics of Solids published their detection of an axion insulator phase of

9906-467: The electromagnetic radiation emitted by X-ray tubes generally has a longer wavelength and lower photon energy than the radiation emitted by radioactive nuclei . Occasionally, one term or the other is used in specific contexts due to historical precedent, based on measurement (detection) technique, or based on their intended use rather than their wavelength or source. Thus, gamma-rays generated for medical and industrial uses, for example radiotherapy , in

10033-422: The exploration of the very violent processes in the universe that produce X-rays. Unlike visible light , which gives a relatively stable view of the universe, the X-ray universe is unstable. It features stars being torn apart by black holes , galactic collisions , and novae , and neutron stars that build up layers of plasma that then explode into space . An X-ray laser device was proposed as part of

10160-517: The field of radiation therapy ) was pioneered by Major John Hall-Edwards in Birmingham , England. Then in 1908, he had to have his left arm amputated because of the spread of X-ray dermatitis on his arm. Medical science also used the motion picture to study human physiology. In 1913, a motion picture was made in Detroit showing a hard-boiled egg inside a human stomach. This early X-ray movie

10287-448: The first Nobel Prize in Physics for his discovery. Röntgen immediately noticed X-rays could have medical applications. Along with his 28 December Physical-Medical Society submission, he sent a letter to physicians he knew around Europe (1 January 1896). News (and the creation of "shadowgrams") spread rapidly with Scottish electrical engineer Alan Archibald Campbell-Swinton being the first after Röntgen to create an X-ray photograph (of

10414-401: The focal plane of the X-ray telescope. The X-ray telescope is based on the popular Wolter-I mirror optics concept. This technique is widely used in almost all X-ray astronomy telescopes. Its mirror is made up of 27 gold-coated nickel shells. These parabolic and hyperbolic shells are confocally arranged to optimize the resolution. The largest shell is 163 mm in diameter, while the smallest

10541-476: The force acting on its detector membrane due to chameleons as 44 ± 18 {\displaystyle 44\pm 18} pNewton, which corresponds to a specific exclusion zone in β γ {\displaystyle \beta _{\gamma }} - β m {\displaystyle \beta _{m}} plane and complements the results obtained by GridPix. Axion An axion ( / ˈ æ k s i ɒ n / )

10668-538: The frequency of the X-rays to the atomic number of the metal. The Coolidge X-ray tube was invented the same year by William D. Coolidge . It made possible the continuous emissions of X-rays. Modern X-ray tubes are based on this design, often employing the use of rotating targets which allow for significantly higher heat dissipation than static targets, further allowing higher quantity X-ray output for use in high-powered applications such as rotational CT scanners. The use of X-rays for medical purposes (which developed into

10795-535: The galactic scale. If they continuously fall into galaxies from the intergalactic medium, they would be denser in " caustic " rings, just as the stream of water in a continuously flowing fountain is thicker at its peak. The gravitational effects of these rings on galactic structure and rotation might then be observable. Other cold dark matter theoretical candidates, such as WIMPs and MACHOs , could also form such rings, but because such candidates are fermionic and thus experience friction or scattering among themselves,

10922-494: The implied dark matter density 0.3 ± 0.1 GeV/cm , indicating said axions would not have enough mass to be the sole component of dark matter. The ORGAN experiment plans to conduct a direct test of this result via the haloscope method. Dark matter cryogenic detectors have searched for electron recoils that would indicate axions. CDMS published in 2009 and EDELWEISS set coupling and mass limits in 2013. UORE and XMASS also set limits on solar axions in 2013. XENON100 used

11049-427: The inside of visually opaque objects. The most often seen applications are in medical radiography and airport security scanners, but similar techniques are also important in industry (e.g. industrial radiography and industrial CT scanning ) and research (e.g. small animal CT ). The penetration depth varies with several orders of magnitude over the X-ray spectrum. This allows the photon energy to be adjusted for

11176-422: The low coupling constant thus predicts that the axion is not scattered out of its state despite its small mass so that the universe would be filled with a very cold Bose–Einstein condensate of primordial axions. Hence, axions could plausibly explain the dark matter problem of physical cosmology . Observational studies are underway, but they are not yet sufficiently sensitive to probe the mass regions if they are

11303-532: The method of generation is not known. One common alternative is to distinguish X- and gamma radiation on the basis of wavelength (or, equivalently, frequency or photon energy), with radiation shorter than some arbitrary wavelength, such as 10  m (0.1  Å ), defined as gamma radiation. This criterion assigns a photon to an unambiguous category, but is only possible if wavelength is known. (Some measurement techniques do not distinguish between detected wavelengths.) However, these two definitions often coincide since

11430-469: The new collaborations at CAST have broadened their research into the wide field of astroparticle physics . Results from these different domains are described below. During the initial years, axion detection was the primary goal of CAST. Although the CAST experiment did not yet observe axions directly, it has constraint the search parameters. Mass and the coupling constant of an axion are primary aspects of its detectability.  Over almost 20 years of

11557-605: The nuclear spin rotation occurs. This precession can be measured using precession magnetometry and if detected, would be evidence for Axions. An experiment using this technique is the Cosmic Axion Spin Precession Experiment (CASPEr). Axions may also be produced at colliders, in particular in electron-positron collisions as well as in ultra-peripheral heavy ion collisions at the Large Hadron Collider at CERN, reinterpreting

11684-415: The operation period, CAST has added very significant details and limitations to the properties of solar axions and axion-like particles. In the initial run period, the first three CAST detectors put an upper limit of  8.8 × 10 − 11 G e V − 1 {\displaystyle \mathrm {8.8\times 10^{-11}GeV^{-1}} } on g

11811-528: The other side of the barrier. Experiments by BFRS and a team led by Rizzo ruled out an axion cause. GammeV saw no events, reported in a 2008 Physics Review Letter. ALPS I conducted similar runs, setting new constraints in 2010; ALPS II began collecting data in May 2023. OSQAR found no signal, limiting coupling, and will continue. Axion-like bosons could have a signature in astrophysical settings. In particular, several works have proposed axion-like particles as

11938-425: The part of his head nearest the X-ray tube: "A plate holder with the plates towards the side of the skull was fastened and a coin placed between the skull and the head. The tube was fastened at the other side at a distance of one-half-inch [1.3 cm] from the hair." Beyond burns, hair loss, and cancer, X-rays can be linked to infertility in males based on the amount of radiation used. In August 1896, H. D. Hawks,

12065-438: The path of the bullet, and McKinley died of septic shock due to bacterial infection six days later. With the widespread experimentation with X‑rays after their discovery in 1895 by scientists, physicians, and inventors came many stories of burns, hair loss, and worse in technical journals of the time. In February 1896, Professor John Daniel and William Lofland Dudley of Vanderbilt University reported hair loss after Dudley

12192-505: The photon production, necessary to allow the X-rays to enter the detector that cannot point directly at the sun, would dissipate the flux so much that the probability of detection would be negligible. In 2013, Christian Beck suggested that axions might be detectable in Josephson junctions ; and in 2014, he argued that a signature, consistent with a mass ≈110 μeV, had in fact been observed in several preexisting experiments. In 2020,

12319-561: The polarized light measurements of Messier 87* by the Event Horizon Telescope were used to constrain the mass of the axion assuming that hypothetical clouds of axions could form around a black hole, rejecting the approximate 10  eV/ c – 10  eV/ c range of mass values. Resonance effects may be evident in Josephson junctions from a supposed high flux of axions from the galactic halo with mass of 110 μeV and density 0.05 GeV/cm compared to

12446-441: The positions of atoms in crystals . X-rays interact with matter in three main ways, through photoabsorption , Compton scattering , and Rayleigh scattering . The strength of these interactions depends on the energy of the X-rays and the elemental composition of the material, but not much on chemical properties, since the X-ray photon energy is much higher than chemical binding energies. Photoabsorption or photoelectric absorption

12573-475: The possibility of new particle discovery. One theory of axions relevant to cosmology had predicted that they would have no electric charge , a very small mass in the range from 1 μeV/ c to 1 eV/ c , and very low interaction cross-sections for strong and weak forces. Because of their properties, axions would interact only minimally with ordinary matter. Axions would also change to and from photons in magnetic fields. The properties of

12700-524: The previous astrophysical limits and has probed numerous relevant axion models of sub-electron-volt mass. CAST was able to constrain the axion-photon coupling constant from the very low up to the hot dark matter sector; and the current search range overlaps with the present cosmic hot dark matter bound which is axion mass, m a ≲ 0.9 e V {\displaystyle m_{a}\lesssim 0.9eV} . The new detectors at CAST are also looking for proposed dark matter candidates such as

12827-512: The primakoff effect. During the search period of 2014 to 2015 the detected signal-to-noise ratio was below the required levels. The sole aim of this detector is to enhance the sensitivity of CAST to energy thresholds around 1 KeV range. This is an improved sensitive detector set up in 2014 behind the X-ray telescope, for the search of solar chameleons which have low threshold energies. The InGrid detector and its granular Timepix pad readout with low energy threshold of 0.1 KeV for photon detection hunts

12954-510: The range of parameters where these elusive particles may exist. CAST has set significant limits on axion coupling to electrons and photons. A 2017 paper using data from the 2013–2015 run reported a new best limit on axion-photon coupling of 0.66×10  /  GeV. Built upon the experience of CAST, a much larger, new-generation, axion helioscope, the International Axion Observatory (IAXO), has been proposed and

13081-476: The ranges of 6–20  MeV , can in this context also be referred to as X-rays. X-ray photons carry enough energy to ionize atoms and disrupt molecular bonds . This makes it a type of ionizing radiation , and therefore harmful to living tissue . A very high radiation dose over a short period of time causes burns and radiation sickness , while lower doses can give an increased risk of radiation-induced cancer . In medical imaging, this increased cancer risk

13208-534: The rays "not only photograph, but also affect the living function". At around the same time, the zoological illustrator James Green began to use X-rays to examine fragile specimens. George Albert Boulenger first mentioned this work in a paper he delivered before the Zoological Society of London in May 1896. The book Sciagraphs of British Batrachians and Reptiles (sciagraph is an obsolete name for an X-ray photograph), by Green and James H. Gardiner, with

13335-405: The residual air in the tube by a high DC voltage of anywhere between a few kilovolts and 100 kV. This voltage accelerated the electrons coming from the cathode to a high enough velocity that they created X-rays when they struck the anode or the glass wall of the tube. The earliest experimenter thought to have (unknowingly) produced X-rays was William Morgan . In 1785 , he presented

13462-428: The rings would be less sharply defined. João G. Rosa and Thomas W. Kephart suggested that axion clouds formed around unstable primordial black holes might initiate a chain of reactions that radiate electromagnetic waves, allowing their detection. When adjusting the mass of the axions to explain dark matter, the pair discovered that the value would also explain the luminosity and wavelength of fast radio bursts , being

13589-511: The role of Θ , naturally relaxing the CP-violation parameter to zero. Wilczek named this new hypothesized particle the "axion" after a brand of laundry detergent because it "cleaned up" a problem, while Weinberg called it "the higglet". Weinberg later agreed to adopt Wilczek's name for the particle. Because it has a non-zero mass, the axion is a pseudo-Nambu–Goldstone boson . QCD effects produce an effective periodic potential in which

13716-452: The same detector and reduces the systematic uncertainties. From 2003 to 2013, the following three detectors were attached to ends of the dipole magnet, all based on the inverse Primakoff effect, to detect the photons converted from the solar axions. After 2013 several new detectors such as the RADES, GridPix, and KWISP were installed, with modified goals and newly enhanced technologies. TPC

13843-494: The so-called misalignment mechanism, generate a cosmological population of cold axions with an abundance depending on the mass of the axion. With a mass above 5  μeV/ c (10 times the electron mass ) axions could account for dark matter , and thus be both a dark-matter candidate and a solution to the strong CP problem. If inflation occurs at a low scale and lasts sufficiently long, the axion mass can be as low as 1 peV/ c . There are two distinct scenarios in which

13970-449: The solar chameleons in this range. The RADES started searching for axion-like dark matter in 2018, and the first results from this detector were published in early 2021. Although no significant axion signal was detected above the noise background during the 2018 to 2021 period, RADES became the first detector to search for axions above 30 μ e V {\displaystyle 30\mu eV} . CAST helioscope (looks at sun)

14097-431: The solution to the dark matter problem with the fuzzy dark matter region starting to be probed via superradiance . High mass axions of the kind searched for by Jain and Singh (2007) would not persist in the modern universe. Moreover, if axions exist, scatterings with other particles in the thermal bath of the early universe unavoidably produce a population of hot axions. Low mass axions could have additional structure at

14224-478: The standard model, QCD, possess a non-trivial vacuum structure that in principle permits violation of the combined symmetries of charge conjugation and parity , collectively known as CP. Together with effects generated by weak interactions , the effective periodic strong CP-violating term, Θ , appears as a Standard Model input – its value is not predicted by the theory, but must be measured. However, large CP-violating interactions originating from QCD would induce

14351-479: The sunward magnetosphere in which X-rays may be produced by axions from the Sun's core. This interpretation of the seasonal variation is disputed by two Italian researchers, who identify flaws in the arguments of the Leicester group that are said to rule out an interpretation in terms of axions. Most importantly, the scattering in angle assumed by the Leicester group to be caused by magnetic field gradients during

14478-504: The transient signal from the encounter between a neutron star and an axion minicluster in the Milky Way . Axions can be produced in the Sun's core when X-rays scatter in strong electric fields. The CAST solar telescope is underway, and has set limits on coupling to photons and electrons. Axions may also be produced within neutron stars by nucleon–nucleon bremsstrahlung . The subsequent decay of axions to gamma rays allows constraints on

14605-405: The tube was suitable for shoulders and knees. An 18-to-23-centimeter (7 to 9 in) spark would indicate a higher vacuum suitable for imaging the abdomen of larger individuals. Since the spark gap was connected in parallel to the tube, the spark gap had to be opened until the sparking ceased to operate the tube for imaging. Exposure time for photographic plates was around half a minute for a hand to

14732-438: The tube were passing through the cardboard to make the screen glow. He found they could also pass through books and papers on his desk. Röntgen threw himself into investigating these unknown rays systematically. Two months after his initial discovery, he published his paper. Röntgen discovered their medical use when he made a picture of his wife's hand on a photographic plate formed due to X-rays. The photograph of his wife's hand

14859-701: The tube. On 3 February 1896, Gilman Frost, professor of medicine at the college, and his brother Edwin Frost, professor of physics, exposed the wrist of Eddie McCarthy, whom Gilman had treated some weeks earlier for a fracture, to the X-rays and collected the resulting image of the broken bone on gelatin photographic plates obtained from Howard Langill, a local photographer also interested in Röntgen's work. Many experimenters, including Röntgen himself in his original experiments, came up with methods to view X-ray images "live" using some form of luminescent screen. Röntgen used

14986-801: The world extensively reported about the new discovery, with a magazine such as Science dedicating as many as 23 articles to it in that year alone. Sensationalist reactions to the new discovery included publications linking the new kind of rays to occult and paranormal theories, such as telepathy. The name X-rays stuck, although (over Röntgen's great objections) many of his colleagues suggested calling them Röntgen rays . They are still referred to as such in many languages, including German , Hungarian , Ukrainian , Danish , Polish , Czech , Bulgarian , Swedish , Finnish , Portuguese , Estonian , Slovak , Slovenian , Turkish , Russian , Latvian , Lithuanian , Albanian , Japanese , Dutch , Georgian , Hebrew , Icelandic , and Norwegian . Röntgen received

15113-474: Was X-rayed. A child who had been shot in the head was brought to the Vanderbilt laboratory in 1896. Before trying to find the bullet, an experiment was attempted, for which Dudley "with his characteristic devotion to science" volunteered. Daniel reported that 21 days after taking a picture of Dudley's skull (with an exposure time of one hour), he noticed a bald spot 5 centimeters (2 in) in diameter on

15240-419: Was disconnected. To detect the hardness of the tube, the spark gap was initially opened to the widest setting. While the coil was operating, the operator reduced the gap until sparks began to appear. A tube in which the spark gap began to spark at around 6.4 centimeters (2.5 in) was considered soft (low vacuum) and suitable for thin body parts such as hands and arms. A 13-centimeter (5 in) spark indicated

15367-462: Was made a haloscope (looks at galactic halo) in late 2017. RADES detector attached to this haloscope has a 1 m long alternating-irises stainless-steel cavity able to search for dark matter axions around 34 μ e V {\displaystyle 34\mu eV} . Further prospects of improving the detector system with enhancements such as superconductive cavities and ferro-magnetic tunings are being looked into. KWISP at CAST

15494-826: Was recorded at a rate of one still image every four seconds. Dr Lewis Gregory Cole of New York was a pioneer of the technique, which he called "serial radiography". In 1918, X-rays were used in association with motion picture cameras to capture the human skeleton in motion. In 1920, it was used to record the movements of tongue and teeth in the study of languages by the Institute of Phonetics in England. In 1914 , Marie Curie developed radiological cars to support soldiers injured in World War I . The cars would allow for rapid X-ray imaging of wounded soldiers so battlefield surgeons could quickly and more accurately operate. From

15621-647: Was reported by Borsanyi et al. (2016). The result was calculated by simulating the formation of axions during the post-inflation period on a supercomputer . Progress in the late 2010s in determining the present abundance of a KSVZ-type axion using numerical simulations lead to values between 0.02 and 0.1 meV, although these results have been challenged by the details on the power spectrum of emitted axions from strings. The axion models originally proposed by Wilczek and by Weinberg chose axion coupling strengths that were so strong that they would have already been detected in prior experiments. It had been thought that

15748-596: Was shot twice in an assassination attempt while attending the Pan American Exposition in Buffalo, New York . While one bullet only grazed his sternum , another had lodged somewhere deep inside his abdomen and could not be found. A worried McKinley aide sent word to inventor Thomas Edison to rush an X-ray machine to Buffalo to find the stray bullet. It arrived but was not used. While the shooting itself had not been lethal, gangrene had developed along

15875-558: Was shown that any very light axion would have been overproduced in the early universe and therefore must be excluded. Pierre Sikivie computed how Maxwell's equations are modified in the presence of an axion in 1983. He showed that these axions could be detected on Earth by converting them to photons, using a strong magnetic field, motivating a number of experiments. For example, the Axion Dark Matter Experiment converts axion dark matter to microwave photons,

16002-412: Was the first photograph of a human body part using X-rays. When she saw the picture, she said "I have seen my death." The discovery of X-rays generated significant interest. Röntgen's biographer Otto Glasser estimated that, in 1896 alone, as many as 49 essays and 1044 articles about the new rays were published. This was probably a conservative estimate, if one considers that nearly every paper around

16129-461: Was the most effective substance. In May 1896, he developed the first mass-produced live imaging device, his "Vitascope", later called the fluoroscope , which became the standard for medical X-ray examinations. Edison dropped X-ray research around 1903, before the death of Clarence Madison Dally , one of his glassblowers. Dally had a habit of testing X-ray tubes on his own hands, developing a cancer in them so tenacious that both arms were amputated in

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