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Author: Publisher: ISBN: Category : Languages : en Pages : 26
Book Description
This chapter will cover the search for dark matter axions based on microwave cavity experiments proposed by Pierre Sikivie. We will start with a brief overview of halo dark matter and the axion as a candidate. The principle of resonant conversion of axions in an external magnetic field will be described as well as practical considerations in optimizing the experiment as a signal-to-noise problem. A major focus of this chapter will be the two complementary strategies for ultra-low noise detection of the microwave photons--the 'photon-as-wave' approach (i.e. conventional heterojunction amplifiers and soon to be quantum-limited SQUID devices), and 'photon-as-particle' (i.e. Rydberg-atom single-quantum detection). Experimental results will be presented; these experiments have already reached well into the range of sensitivity to exclude plausible axion models, for limited ranges of mass. The section will conclude with a discussion of future plans and challenges for the microwave cavity experiment.
Author: Publisher: ISBN: Category : Languages : en Pages : 26
Book Description
This chapter will cover the search for dark matter axions based on microwave cavity experiments proposed by Pierre Sikivie. We will start with a brief overview of halo dark matter and the axion as a candidate. The principle of resonant conversion of axions in an external magnetic field will be described as well as practical considerations in optimizing the experiment as a signal-to-noise problem. A major focus of this chapter will be the two complementary strategies for ultra-low noise detection of the microwave photons--the 'photon-as-wave' approach (i.e. conventional heterojunction amplifiers and soon to be quantum-limited SQUID devices), and 'photon-as-particle' (i.e. Rydberg-atom single-quantum detection). Experimental results will be presented; these experiments have already reached well into the range of sensitivity to exclude plausible axion models, for limited ranges of mass. The section will conclude with a discussion of future plans and challenges for the microwave cavity experiment.
Author: Ian Stern Publisher: Dissertation Discovery Company ISBN: 9780530000046 Category : Languages : en Pages : 202
Book Description
Dissertation Discovery Company and University of Florida are dedicated to making scholarly works more discoverable and accessible throughout the world. This dissertation, "Microwave Cavities for Axion Dark Matter Detectors" by Ian Phillip Stern, was obtained from University of Florida and is being sold with permission from the author. The content of this dissertation has not been altered in any way. We have altered the formatting in order to facilitate the ease of printing and reading of the dissertation. Abstract: Nearly all astrophysical and cosmological data point convincingly to a large component of cold dark matter (CDM) in the Universe. The axion particle, first theorized as a solution to the strong charge-conjugate/parity problem of quantum chromodynamics, has been established as a prominent CDM candidate. Cosmic observation and particle physics experiments have bracketed the unknown mass of such CDM axions between approximately microelectronvolts and millielectronvolts. The Axion Dark Matter eXperiment (ADMX) is a direct-detection CDM axion search which has set limits at the KSVZ coupling of the axion to two photons for axion masses between 1.9 and 3.7 microelectronvolts. But most of the viable search-space of axions has yet to be probed. It is now evident that the current cavity design for ADMX does not provide for successful scanning above 4 microelectronvolts ( 1 gigahertz), and new microwave cavity technologies need to be developed to enable searching for CDM axions of greater mass. A broad study into factors that affect high-frequency microwave cavity was conducted in an effort to expand the capabilities of current haloscope detectors. The study evaluated the effects of symmetry breaking on axion search potential and assessed state-of-the-art cavity technologies relevant to haloscope detectors. Periodic arrays of tuning rods or vanes were evaluated for increasing the search range of haloscopes, and a prototype haloscope cavity and an in-situ mode identification technique were developed and tested. The study revealed several significant findings. The cause for frequency gaps in search modes at mode crossing is mode mixing, which occurs due to longitudinal symmetry breaking. Symmetry breaking also results in increased mode crowding, which hinders mode identification and tracking, and further increases mode mixing. Arrays of tuning rods or vanes produce tunable modes, but result in increased sensitivity to symmetry breaking, requiring advanced mode identification techniques and additional studies.
Author: Publisher: ISBN: Category : Languages : en Pages : 70
Book Description
The axion remains, after nearly 30 years, the most compelling and elegant solution to the strong-CP problem, i.e. why this symmetry is protected in QCD in spite of CP violation elsewhere. The axion is expected to be extremely light, and possess extraordinarily feeble couplings to matter and radiation. Because of its small couplings, the axion has defied experimental confirmation and is unlikely to be discovered in conventional laboratory experiments (i.e. production-detection). Nevertheless, a sufficiently light axion would have been produced abundantly in the Big Bang and is an excellent candidate for the dark matter of the Universe. Through the axion's two-photon coupling, implying axion-photon mixing in an external electromagnetic field, galactic halo axions may be feasibly detected by their resonant conversion to RF photons in a microwave cavity permeated by magnetic field with current technology. Over the past decade experiments have already set interesting limits in mass and coupling; upgrades in progress to photon detection schemes at or below the standard quantum limit will soon enable definitive searches. Similarly, axions produced in the solar burning core might be detectable by their conversion to x-rays in a magnetic helioscope. Indeed current published limits already equal the best bounds on axion-photon coupling inferred from the concordance of stellar evolution models and observations, from horizontal branch stars. Significant improvements in both the mass range and sensitivity of the axion helioscope technique will be forthcoming in the next few years. This report will first summarize the theoretical background of the axion, and laboratory, astrophysical and cosmological limits on its mass and couplings. Cavity microwave searches for cosmic axions will then be reviewed, focusing on the current large-scale experiments (ADMX in the US; CARRACK in Japan), and their enabling technologies (HFET and SQUID amplifiers; Rydberg-atom single-quantum detection). Last, the searches for solar axions will be discussed, with particular attention to the CAST experiment at CERN. The conclusion provides a basis for cautious optimism that a definitive verdict on the axion, or at least its role as a dark matter component, could be expected within a decade.
Author: Publisher: ISBN: Category : Languages : en Pages : 12
Book Description
This research project is a collaboration with the axion search experiment at Lawrence Livermore National Laboratory. The axion is a particle that affects two important issues in particle physics and astrophysics: the origin of CP symmetry in the strong interactions, and the composition of the dark-matter of the universe. First predicted in 1978, present laboratory, astrophysical, and cosmological constraints suggest axions have a mass in the 1 [mu]eV-1 meV range. Axions are especially significant as dark matter if their mass is in the range 1-10 [mu]eV. These dark matter axions may be detected by their coupling to photons through the E - B interaction in a tunable high-Q microwave cavity permeated by a strong external magnetic field. The present experiment is the first cavity experiment with the sensitivity to possibly observe cosmic axions. It has recently begun taking data and will operate for the next several years. The University of Florida plans to contribute to the operation of this detector and to the design and prototyping of cavities for the experiment.
Author: Gianpaolo Carosi Publisher: Springer Nature ISBN: 3030437612 Category : Science Languages : en Pages : 173
Book Description
The nature of dark matter remains one of the preeminent mysteries in physics and cosmology. It appears to require the existence of new particles whose interactions with ordinary matter are extraordinarily feeble. One well-motivated candidate is the axion, an extraordinarily light neutral particle that may possibly be detected by looking for their conversion to detectable microwaves in the presence of a strong magnetic field. This has led to a number of experimental searches that are beginning to probe plausible axion model space and may reveal the axion in the near future. These proceedings discuss the challenges of designing and operating tunable resonant cavities and detectors at ultralow temperatures. The topics discussed here have potential application far beyond the field of dark matter detection and may be applied to resonant cavities for accelerators as well as designing superconducting detectors for quantum information and computing applications. This work is intended for graduate students and researchers interested in learning the unique requirements for designing and operating microwave cavities and detectors for direct axion searches and to introduce several proposed experimental concepts that are still in the prototype stage.
Author: Markus Kuster Publisher: Springer Science & Business Media ISBN: 3540735178 Category : Science Languages : en Pages : 248
Book Description
Axions are peculiar hypothetical particles that could both solve the CP problem of quantum chromodynamics and at the same time account for the dark matter of the universe. Based on a series of lectures by world experts in this field held at CERN (Geneva), this volume provides a pedagogical introduction to the theory, cosmology and astrophysics of these fascinating particles and gives an up-to-date account of the status and prospect of ongoing and planned experimental searches.
Author: Markus Kuster Publisher: Springer ISBN: 3540735186 Category : Science Languages : en Pages : 248
Book Description
Axions are peculiar hypothetical particles that could both solve the CP problem of quantum chromodynamics and at the same time account for the dark matter of the universe. Based on a series of lectures by world experts in this field held at CERN (Geneva), this volume provides a pedagogical introduction to the theory, cosmology and astrophysics of these fascinating particles and gives an up-to-date account of the status and prospect of ongoing and planned experimental searches.
Author: Publisher: ISBN: Category : Languages : en Pages :
Book Description
We review the status of two ongoing large-scale searches for axions which may constitute the dark matter of our Milky Way halo. The experiments are based on the microwave cavity technique proposed by Sikivie, and marks a ''second-generation'' to the original experiments performed by the Rochester-Brookhaven-Fermilab collaboration, and the University of Florida group.
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Author: Ian Stern
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Author: Gianpaolo Carosi
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