Papers by konstantin zioutas
The Identification of Dark Matter - Proceedings of the Sixth International Workshop, 2007
We discuss solar signatures suggesting axion(-like) particles. The working principle of axion hel... more We discuss solar signatures suggesting axion(-like) particles. The working principle of axion helioscopes can be behind unexpected solar X-ray emission, even above 3.5 keV from non-flaring active regions. Because this is associated with solar magnetic fields (~B 2 ), which become in this framework the catalyst and not the otherwise suspected / unspecified energy source of solar X-rays. In addition, the built-in fine tuning we may (not) be able to fully reconstruct, and, we may (not?) be able to copy. Solar axion signals are transient X-ray brightenings, or, continuous radiation from the corona violating the second law of thermodynamics and Planck"s law of black body radiation. To understand the corona problem and other mysteries like flares, sunspots, etc., we arrive at two exotica: a) trapped, radiatively decaying, massive axions allow a continuous self-irradiation of the Sun, explaining the sudden temperature inversion ~2000 km above the surface and b) outstreaming light axions interact with local fields (~B 2 ), depending crucially on the plasma frequency which must match the axion rest mass, explaining the otherwise unpredictable transient, but also continuous, solar phenomena. Then, the photon energy of a related phenomenon might point at the birth place of involved axions. For example, this suggests that the ~2 MK solar corona has its axion roots at the top of the radiative zone. The predicted B ≈ 10-50 T make this place a coherent axion source, while the multiple photon scattering enhances the photon-to-axion conversion unilaterally, since axions escape. We conclude that the energy range below some 100 eV is a window of opportunity for axion searches, and that it coincides with a) the derived photon energies for an external self-irradiation of the Sun, which has to penetrate until the transition region, and b) with the bulk of the soft solar X-ray luminosity of unknown origin. Thus, (in)direct signatures support axions or the like as an explanation of enigmatic behavior in the Sun and beyond; e.g., the otherwise unexplained "solar oxygen crisis" taking into account related observations (~B 2 ) in pores, which is associated with X-ray emission. Axion antennas could take advantage of such a feed back. Finally, the observed soft X-ray emission from the quiet Sun at highest latitudes as well as the extended activity associated with magnetic structures crossing the solar disk centre suggest that a multicomponent axion(-like) scenario is at work.
The Astrophysical Journal, 2004
We have studied published data from the Yohkoh solar X-ray mission, with the purpose of searching... more We have studied published data from the Yohkoh solar X-ray mission, with the purpose of searching for signals from radiative decays of new, as yet undiscovered massive neutral particles. This search is based on the prediction that solar axions of the Kaluza-Klein type should result in the emission of X-rays from the Sun direction beyond the limb with a characteristic radial distribution. These X-rays should be observed more easily during periods of quiet Sun. An additional signature is the observed emission of hard X-rays by SMM, NEAR and RHESSI. The recent observation made by RHESSI of a continuous emission from the non-flaring Sun of X-rays in the 3 to ∼ 15 keV range fits the generic axion scenario. This work also suggests new analyses of existing data, in order to exclude instrumental effects; it provides the rationale for targeted observations with present and upcoming (solar) X-ray telescopes, which can provide the final answer on the nature of the signals considered here. Such measurements become more promising during the forthcoming solar cycle minimum with an increased number of quiet Sun periods.
Symmetry
We investigate the prospects for the direct detection of dark matter (DM) particles, incident on ... more We investigate the prospects for the direct detection of dark matter (DM) particles, incident on the upper atmosphere. A recent work relating the burst-like temperature excursions in the stratosphere at heights of ≈38–47 km with low speed incident invisible streaming matter is the motivation behind this proposal. As an example, dark photons could match the reasoning presented in that work provided they constitute part of the local DM density. Dark photons emerge as a U(1) symmetry within extensions of the standard model. Dark photons mix with real photons with the same total energy without the need for an external field, as would be required, for instance, for axions. Furthermore, the ionospheric plasma column above the stratosphere can resonantly enhance the dark photon-to-photon conversion. Noticeably, the stratosphere is easily accessible with balloon flights. Balloon missions with up to a few tons of payload can be readily assembled to operate for months at such atmospheric heig...
arXiv (Cornell University), Dec 30, 2011
Chameleon particles, which could explain dark energy, are in many ways similar to axions, suggest... more Chameleon particles, which could explain dark energy, are in many ways similar to axions, suggesting that an axion helioscope can be used for chameleon detection. The distinguishing property of chameleon particles is that, unlike Standard Model particles, their effective masses depend upon the ambient matter-energy density. The associated total internal reflection of chameleons up to keV energies by a dense layer of material, which would occur at grazing incidence on the mirrors of an X-ray telescope, lead to new experimental techniques for detecting such particles. In this short note we discuss when this total internal reflection can happen and how it can be implemented in existing or future state-of-the-art chameleon telescopes. Solar Chameleons would be emitted mainly with energies below a few keV suggesting the X-ray telescope as the basic component in chameleon telescopy. The implementation of this idea is straightforward, but it deserves further scrutiny. It seems promising to prepare and run a dark energy particle candidate detection experiment combining existing equipment. For example, large volumes and strong solenoid magnetic fields, which are not appropriate for solar axion investigations, are attractive from the point of view of chameleon telescopy.
arXiv (Cornell University), Oct 31, 2013
Dark sectors, consisting of new, light, weakly-coupled particles that do not interact with the kn... more Dark sectors, consisting of new, light, weakly-coupled particles that do not interact with the known strong, weak, or electromagnetic forces, are a particularly compelling possibility for new physics. Nature may contain numerous dark sectors, each with their own beautiful structure, distinct particles, and forces. This review summarizes the physics motivation for dark sectors and the exciting opportunities for experimental exploration. It is the summary of the Intensity Frontier subgroup "New, Light, Weakly-coupled Particles" of the Community Summer Study 2013 (Snowmass). We discuss axions, which solve the strong CP problem and are an excellent dark matter candidate, and their generalization to axion-like particles. We also review dark photons and other dark-sector particles, including sub-GeV dark matter, which are theoretically natural, provide for dark matter candidates or new dark matter interactions, and could resolve outstanding puzzles in particle and astro-particle physics. In many cases, the exploration of dark sectors can proceed with existing facilities and comparatively modest experiments. A rich, diverse, and lowcost experimental program has been identified that has the potential for one or more game-changing discoveries. These physics opportunities should be vigorously pursued in the US and elsewhere.
Η συμμετρία φορτίου-ομοτιμίας (CP Symmetry) αποτελεί τη σύζευξη των συμμετριών φορτίου (C Symmetr... more Η συμμετρία φορτίου-ομοτιμίας (CP Symmetry) αποτελεί τη σύζευξη των συμμετριών φορτίου (C Symmetry) και ομοτιμίας (P Symmetry) και θεωρητικά προβλέπεται η παραβίασή της έτσι ώστε να εξηγείται η υπερίσχυση της ύλης έναντι της αντιύλης στις στιγμές που ακολούθησαν τη Μεγάλη Έκρηξη. Η παραβίασή της από τις ασθενείς αλληλεπιδράσεις αποδείχθηκε πειραματικά το 1964 από τους James W. Cronin και Val L. Fitch. Ωστόσο, η Κβαντική Χρωμοδυναμική (QCD), η οποία αποτελεί την επικρατέστερη θεωρία περιγραφής των ισχυρών αλληλεπιδράσεων μεταξύ των quarks και των γκλουονίων, δε φαίνεται να την παραβιάζει κάτι που αντιτίθεται στη θεωρητική πρόβλεψη. Πράγματι, μη διαταρακτικά φαινόμενα της Κβαντικής Χρωμοδυναμικής μπορούν να επάγουν έναν επιπλέον όρο στη λαγκρανζιανή του Καθιερωμένου Προτύπου ο οποίος οδηγεί στην παραβίαση της συμετρίας φορτίου-ομοτιμίας. Ωστόσο, καμμία πειραματική ένδειξη για κάτι τέτοιο δεν υπάρχει μέχρι σήμερα. Αυτή η συμπεριφορά της Κβαντικής Χρωμοδυναμικής συνιστά ένα πρόβλημα γνω...
Dark energy models, such as the chameleon, where the acceleration of the expansion of the univers... more Dark energy models, such as the chameleon, where the acceleration of the expansion of the universe results from the dynamics of a scalar field coupled to matter, suffer from the potential existence of a fifth force. Three known mechanisms have been proposed to restore General Relativity in the solar system and the laboratory, which are the symmetron/Damour-Polyakov effect, the Vainshtein property and the chameleon screening. Here, we propose to probe the existence of chameleons in the laboratory, considering their particle physics consequences. We envisage the resonant and non-resonant production of chameleons in the sun and their back-conversion into X-ray photons in a solar helioscope pipe such as the one used by CAST. A detection of these X-rays would indicate the existence of chameleons. We focus on a template model for the solar magnetic field: a constant magnetic field in a narrow shell surrounding the tachocline. The X-ray photons in a helioscope pipe obtained from back-conve...
arXiv: Solar and Stellar Astrophysics, 2012
Chameleon particles, which could explain dark energy, are in many ways similar to axions, suggest... more Chameleon particles, which could explain dark energy, are in many ways similar to axions, suggesting that an axion helioscope can be used for chameleon detection. The distinguishing property of chameleon particles is that, unlike Standard Model particles, their effective masses depend upon the ambient matter-energy density. The associated total internal reflection of chameleons up to keV energies by a dense layer of material, which would occur at grazing incidence on the mirrors of an X-ray telescope, lead to new experimental techniques for detecting such particles. We discuss here when this total internal reflection can happen and how it can be implemented in existing or future state-of-the-art chameleon telescopes. Solar Chameleons would be emitted mainly with energies below a few keV suggesting the X-ray telescope as the basic component in chameleon telescopy. The implementation of this idea is straightforward, but it deserves further scrutiny. It seems promising to prepare and r...
A new search strategy for the detection of the elusive dark matter (DM) axion is proposed. The id... more A new search strategy for the detection of the elusive dark matter (DM) axion is proposed. The idea is based on streaming DM axions, whose flux might get temporally enormously enhanced due to gravitational lensing. This can happen if the Sun or some planet (including the Moon) is found along the direction of a DM stream propagating towards the Earth location. The experimental requirements to the axion haloscope are a wide-band performance combined with a fast axion rest mass scanning mode, which are feasible. Once both conditions have been implemented in a haloscope, the axion search can continue parasitically almost as before. Interestingly, some new DM axion detectors are operating wide-band by default. In order not to miss the actually unpredictable timing of a potential short duration signal, a network of co-ordinated axion antennae is required, preferentially distributed world-wide. The reasoning presented here for the axions applies to some degree also to any other DM candidates like the WIMPs.
arXiv: Instrumentation and Detectors, 2017
A new search strategy for the detection of the elusive dark matter (DM) axion is proposed. The id... more A new search strategy for the detection of the elusive dark matter (DM) axion is proposed. The idea is based on streaming DM axions, whose flux might get temporally enormously enhanced due to gravitational lensing. This can happen if the Sun or some planet (including the Moon) is found along the direction of a DM stream propagating towards the Earth location. The experimental requirements to the axion haloscope are a wide-band performance combined with a fast axion rest mass scanning mode, which are feasible. Once both conditions have been implemented in a haloscope, the axion search can continue parasitically almost as before. Interestingly, some new DM axion detectors are operating wide-band by default. In order not to miss the actually unpredictable timing of a potential short duration signal, a network of co-ordinated axion antennae is required, preferentially distributed world-wide. The reasoning presented here for the axions applies to some degree also to any other DM candidat...
arXiv: High Energy Physics - Experiment, 2020
We investigate the prospects for direct detection of Dark Matter (DM) particles, such as dark pho... more We investigate the prospects for direct detection of Dark Matter (DM) particles, such as dark photons, incident on the upper atmosphere. A recent work relates the burst-like temperature excursions in the stratosphere at heights of ~38-47 km with incident invisible streaming matter. Surprisingly, dark photons match the reasoning presented in that work provided they constitute part of the local DM density. Dark photons mix with real photons with the same total energy without the need for an external field as would be required for instance for axions. Furthermore, the ionospheric plasma column above the stratosphere can enhance the dark photon to photon conversion due to resonance. The stratosphere is easily accessible via balloon flights. Balloon missions with up to a few tons of payload can be readily assembled to operate for 1-2 months at such atmospheric heights making for realistic short term endeavor of on-site direct DM search following this proposal. The approach need not be li...
Proceedings of International Europhysics Conference on High Energy Physics — PoS(HEP2005), 2007
AIP Conference Proceedings, 2004
A new experiment, the CERN Axion Solar Telescope (CAST) was installed and commissioned in 2002. I... more A new experiment, the CERN Axion Solar Telescope (CAST) was installed and commissioned in 2002. Its aim is to experimentally prove the existence of an as yet hypothetical particle predicted by theory as a solution of the strong CP problem and possible candidate for galactic dark matter. The heart of the detector consists of a decommissioned 10-m long LHC superconducting dipole prototype magnet, providing a magnetic field of up to 9.5 T. The whole telescope assembly is aligned with high precision to the core of the sun. If they exist, axions could be copiously produced in the core of the sun and converted into photons within the transverse magnetic field of the telescope. The converted low-energy solar axion spectrum, peaked around a mean energy of 4.4 keV, can then be focused by a special x-ray mirror system and detected by low-background photon detectors, installed on each end of the telescopes twin beam pipes. This paper describes the external and proximity cryogenic system and magnet commissioning as well as the first operational experience with the overall telescope assembly.
Journal of Physics: Conference Series, 2015
The IAXO (International Axion Experiment) is a fourth generation helioscope with a sensitivity, i... more The IAXO (International Axion Experiment) is a fourth generation helioscope with a sensitivity, in terms of detectable signal counts, at least 10 4 better than CAST phase-I, resulting in sensitivity on gaγ one order of magnitude better. To achieve this performance IAXO will count on a 8-coil toroidal magnet with 60 cm diameter bores and equipped with X-ray focusing optics into 0.20 cm 2 spots coupled to ultra-low background Micromegas X-ray detectors. The magnet will be on a platform that will allow solar tracking for 12 hours per day. The next short term objectives are to prepare a Technical Design Report and to construct the first prototypes of the hardware main ingredients: demonstration coil, X-ray optics and low background detector while refining the physics case and studying the feasibility studies for Dark Matter axions.
Physics Procedia, 2015
The International Axion Observatory (IAXO) is a proposed 4 th -generation axion helioscope with t... more The International Axion Observatory (IAXO) is a proposed 4 th -generation axion helioscope with the primary physics research goal to search for solar axions via their Primakoff conversion into photons of 1 -10 keV energies in a strong magnetic field. IAXO will achieve a sensitivity to the axion-photon coupling g aγ down to a few ×10 -12 GeV -1 for a wide range of axion masses up to ∼ 0.25 eV. This is an improvement over the currently best (3 rd generation) axion helioscope, the CERN Axion Solar Telescope (CAST), of about 5 orders of magnitude in signal strength, corresponding to a factor ∼ 20 in the axion photon coupling. IAXO's sensitivity relies on the construction of a large superconducting 8-coil toroidal magnet of 20 m length optimized for axion research. Each of the eight 60 cm diameter magnet bores is equipped with x-ray optics focusing the signal photons into ∼ 0.2 cm 2 spots that are imaged by very low background x-ray detectors. The magnet will be built into a structure with elevation and azimuth drives that will allow solar tracking for 12 hours each day. This contribution is a summary of our papers [1, 2, 3] and we refer to these for further details.
The axion, an as yet hypothetical particle predicted from the solution of the strong CP problem, ... more The axion, an as yet hypothetical particle predicted from the solution of the strong CP problem, constitutes a prime candidate for the galactic dark matter and also arises in supersymmetry and superstring theories. If existing, axions should be copiously produced in stellar interiors and there are theoretical expectations for a low-energy axion emission spectrum peaked around a mean energy of
Physics Letters B, 2014
Light scalar fields can drive accelerated expansion of the universe. Hence, scalars are obvious d... more Light scalar fields can drive accelerated expansion of the universe. Hence, scalars are obvious dark energy candidates. To make these models compatible with test of General Relativity in the solar system and fifth force searches on earth, one needs to screen them. One possibility is the chameleon mechanism, which renders an effective mass depending on the local energy density. If chameleons exist, they can be produced in the sun and detected on earth through their radiation pressure. We calculate the solar chameleon spectrum and the sensitivity of an experiment to be carried out at CAST, CERN, utilizing a radiation pressure sensor currently under development at INFN, Trieste. We show, that such an experiment will be sensitive to a wide range of model parameters and signifies a pioneering effort searching for chameleons in unprobed paramterspace.
Nuclear Physics B-Proceedings Supplements, 2002
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Papers by konstantin zioutas