Understanding propagation of scintillation light is critical for maximizing the discovery potential of next-generation liquid xenon detectors that use dual-phase time projection chamber technology. This work describes a detailed optical... more
Understanding propagation of scintillation light is critical for maximizing the discovery potential of next-generation liquid xenon detectors that use dual-phase time projection chamber technology. This work describes a detailed optical simulation of the DARWIN detector implemented using Chroma, a GPU-based photon tracking framework. To evaluate the framework and to explore ways of maximizing efficiency and minimizing the time of light collection, we simulate several variations of the conventional detector design. Results of these selected studies are presented. More generally, we conclude that the approach used in this work allows one to investigate alternative designs faster and in more detail than using conventional Geant4 optical simulations, making it an attractive tool to guide the development of the ultimate liquid xenon observatory.
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We derive two features of axion cosmology that may have cosmological implications, whether or not axions are dark matter: For the full range of allowed axion masses, the evolution of a cosmic axion background allows large CP violation... more
We derive two features of axion cosmology that may have cosmological implications, whether or not axions are dark matter: For the full range of allowed axion masses, the evolution of a cosmic axion background allows large CP violation until temperatures as low as $\sim$ 2 GeV, and once the axion field begins to oscillate, the cosmological axion field's relaxation to its ground state can briefly provide a new departure from thermal equilibrium, via time-varying CP violation. During both of these periods, the Strong CP violating parameter $\bar\theta$ can be as large as O(1).
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We detail the sensitivity of the proposed liquid xenon DARWIN observatory to solar neutrinos via elastic electron scattering. We find that DARWIN will have the potential to measure the fluxes of five solar neutrino components: pp, $$^7$$... more
We detail the sensitivity of the proposed liquid xenon DARWIN observatory to solar neutrinos via elastic electron scattering. We find that DARWIN will have the potential to measure the fluxes of five solar neutrino components: pp, $$^7$$ 7 Be, $$^{13}$$ 13 N, $$^{15}$$ 15 O and pep. The precision of the $$^{13}$$ 13 N, $$^{15}$$ 15 O and pep components is hindered by the double-beta decay of $$^{136}$$ 136 Xe and, thus, would benefit from a depleted target. A high-statistics observation of pp neutrinos would allow us to infer the values of the electroweak mixing angle, $$\sin ^2\theta _w$$ sin 2 θ w , and the electron-type neutrino survival probability, $$P_{ee}$$ P ee , in the electron recoil energy region from a few keV up to 200 keV for the first time, with relative precision of 5% and 4%, respectively, with 10 live years of data and a 30 tonne fiducial volume. An observation of pp and $$^7$$ 7 Be neutrinos would constrain the neutrino-inferred solar luminosity down to 0.2%. A co...
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The DARWIN observatory is a proposed next-generation experiment to search for particle dark matter and for the neutrinoless double beta decay of $$^{136}$$ 136 Xe. Out of its 50 t total natural xenon inventory, 40 t will be the active... more
The DARWIN observatory is a proposed next-generation experiment to search for particle dark matter and for the neutrinoless double beta decay of $$^{136}$$ 136 Xe. Out of its 50 t total natural xenon inventory, 40 t will be the active target of a time projection chamber which thus contains about 3.6 t of $$^{136}$$ 136 Xe. Here, we show that its projected half-life sensitivity is $$2.4\times {10}^{27}\,{\hbox {year}}$$ 2.4 × 10 27 year , using a fiducial volume of 5 t of natural xenon and 10 year of operation with a background rate of less than 0.2 events/(t $$\cdot $$ · year) in the energy region of interest. This sensitivity is based on a detailed Monte Carlo simulation study of the background and event topologies in the large, homogeneous target. DARWIN will be comparable in its science reach to dedicated double beta decay experiments using xenon enriched in $$^{136}$$ 136 Xe.
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We summarize existing constraints on the epoch of reionization and discuss the observational probes that are sensitive to the process. We focus on the role large scale polarization can play. Polarization probes the integrated optical... more
We summarize existing constraints on the epoch of reionization and discuss the observational probes that are sensitive to the process. We focus on the role large scale polarization can play. Polarization probes the integrated optical depth across the entire epoch of reionization. Future missions such as Planck and CMBPol will greatly enhance our knowledge of the reionization history, allowing us
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The nature of dark matter and properties of neutrinos are among the most pressing issues in contemporary particle physics. The dual-phase xenon time-projection chamber is the leading technology to cover the available parameter space for... more
The nature of dark matter and properties of neutrinos are among the most pressing issues in contemporary particle physics. The dual-phase xenon time-projection chamber is the leading technology to cover the available parameter space for weakly interacting massive particles, while featuring extensive sensitivity to many alternative dark matter candidates. These detectors can also study neutrinos through neutrinoless double-beta decay and through a variety of astrophysical sources. A next-generation xenon-based detector will therefore be a true multi-purpose observatory to significantly advance particle physics, nuclear physics, astrophysics, solar physics, and cosmology. This review article presents the science cases for such a detector.
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Research Interests: Physics and Cosmic String
Research Interests: Physics, Particle Physics, Dark Matter, Dust (Astronomy & Astrophysics), Neutrino, and 15 morePhysical sciences, Search, Xenon, Science Technology, Solar Neutrinos, Axion, Time Projection Chamber, Neutrinoless Double Beta Decay, Scintillation, Zeplin-III, Photomultiplier Tubes, Gas, axions, Neutrino Detectors, and Gran Sasso
Abstract The anomalous magnetic moment of the muon ( g − 2) μ imposes constraints on the masses and mixings of spin-zero leptons, gauge fermions, and Higgs fermions in minimal models of low energy supergravity. We demonstrate that there... more
Abstract The anomalous magnetic moment of the muon ( g − 2) μ imposes constraints on the masses and mixings of spin-zero leptons, gauge fermions, and Higgs fermions in minimal models of low energy supergravity. We demonstrate that there exist only limited values of the parameters in these models that are ruled out by existing limits on ( g − 2) μ .
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Research Interests: Philosophy and Astronomy
... PHYSICAL REVIEW LETTERS Solar-Neutrino Oscillations Lawrence Krauss Lyman Laboratory of Physics, Harvard University ... m2 _ 10-8 eV2 would completely separate over the Earth-sun distance because of their different group velocities,... more
... PHYSICAL REVIEW LETTERS Solar-Neutrino Oscillations Lawrence Krauss Lyman Laboratory of Physics, Harvard University ... m2 _ 10-8 eV2 would completely separate over the Earth-sun distance because of their different group velocities, and true oscillations (though ...
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... We must conclude that this Zp charge does not depend on whether the particle has crossed theevent horizon, and, in particular, that it re-tains its meaning (and induces the ... Identification of such anomalies is a difficult but well... more
... We must conclude that this Zp charge does not depend on whether the particle has crossed theevent horizon, and, in particular, that it re-tains its meaning (and induces the ... Identification of such anomalies is a difficult but well developed art, 14 into which we shall not enter here ...
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We present the results of new theoretical work on surface 7 Li and 6 Li evolution in the oldest halo stars along with a new and refined analysis of the predicted primordial lithium abundance resulting from big-bang ...
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... bounds. We now turn to the question of the distribution of dark-matter particles inside the Earth. We assume that T Ien cv I') IE Li-mx (GeV) 2080 33 X[ I -exp(-0.032m,,,)] SOLAR SYSTEM CONSTRAINTS AND SIGNATURES... more
... bounds. We now turn to the question of the distribution of dark-matter particles inside the Earth. We assume that T Ien cv I') IE Li-mx (GeV) 2080 33 X[ I -exp(-0.032m,,,)] SOLAR SYSTEM CONSTRAINTS AND SIGNATURES FOR.. ...
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I review various aspects of the role neutrinos have played in shaping various cosmological observables: the nature of large scale structure, observed fluctuations in the CMB, the nature of matter, and the shape of things to come. (Invited... more
I review various aspects of the role neutrinos have played in shaping various cosmological observables: the nature of large scale structure, observed fluctuations in the CMB, the nature of matter, and the shape of things to come. (Invited review lecture III International Workshop on NO-VE, Venice, 2006)
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I review the challenges and problems facing the standard cosmological model, involving an Ω=1 Universe dominated by non-baryonic dark matter, which arise due to: age estimates of the universe, estimates of the baryon fraction of the... more
I review the challenges and problems facing the standard cosmological model, involving an Ω=1 Universe dominated by non-baryonic dark matter, which arise due to: age estimates of the universe, estimates of the baryon fraction of the universe, and structure formation. Certain of these problems are exacerbated, and certain of these are eased, by the inclusion of some component to the energy density of matter from massive neutrinos. I conclude with a comparison of the two favored current cosmological models, involving either a mixture of cold dark matter and hot dark matter, or the inclusion of a cosmological constant.
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I first outline new results on the angular modulation of WIMP dark matter scattering on targets in terrestrial laboratories, based on our uncertainties of the WIMP halo distribution, I then outline an exciting new result which indicates... more
I first outline new results on the angular modulation of WIMP dark matter scattering on targets in terrestrial laboratories, based on our uncertainties of the WIMP halo distribution, I then outline an exciting new result which indicates that for the high end of allowed SUSY WIMP scattering cross sections there exists a new distribution of WIMP dark matter in our solar system which could produce a dramatically different signal from halo WIMP dark matter in terrestrial detectors.
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We examine whether a cosmologically significant distribution of dark galaxy group or cluster-sized objects can have an optical depth for multiple imaging of distant background sources which is comparable to that from known galaxies while... more
We examine whether a cosmologically significant distribution of dark galaxy group or cluster-sized objects can have an optical depth for multiple imaging of distant background sources which is comparable to that from known galaxies while at the same time producing angular splittings of the same order of magnitude. Our purpose is to explore whether such objects could realistically account for some of the observed lenses. Modeling such systems as isothermal spheres with core radii, and assuming a Schechter-type distribution function, we find that independent of the cosmology (open, flat matter dominated, or flat cosmological constant dominated) an allowed parameter range exists which is comparable in velocity dispersion to that for known compact groups of galaxies, although the preferred core radii are somewhat smaller than that normally assumed for compact groups. Dark cluster-sized objects, on the other hand, cannot reproduce the observed lensing characteristics. If the one known Da...
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In this brief review of recent theoretical developments associated with the search for dark matter I describe the following: why baryons are now ruled out as dark matter candidates; SUSY WIMPS and signatures in the MSSM and NMSSM why... more
In this brief review of recent theoretical developments associated with the search for dark matter I describe the following: why baryons are now ruled out as dark matter candidates; SUSY WIMPS and signatures in the MSSM and NMSSM why claimed indirect signatures are probably not WIMP related, why axions may be of new interest, how WIMP detection might tell us about the galactic halo, and how theorists are preparing to avoid the next generation of experimental constraints.
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We consider the status of Higgs Inflation in light of the recently announced detection of B-modes in the polarization of the cosmic microwave background radiation by the BICEP2 collaboration. In order for the primordial B-mode signal to... more
We consider the status of Higgs Inflation in light of the recently announced detection of B-modes in the polarization of the cosmic microwave background radiation by the BICEP2 collaboration. In order for the primordial B-mode signal to be observable by BICEP2, the energy scale of inflation must be high, V_ inf≈ 2 × 10^16. Higgs Inflation generally predicts a small amplitude of tensor perturbations, and therefore it is natural to ask if Higgs Inflation might accommodate this new measurement. We find the answer is essentially no, unless one considers either extreme fine tuning, or possibly adding new beyond the standard model fields, which remove some of the more attractive features of the original idea. We also explore the possible importance of a factor that has not previously been explicitly incorporated, namely the gauge dependence of the effective potential used in calculating inflationary observables, e.g. n_S and r, to see if this might provide additional wiggle room. Such gau...
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I review here recent developments which have affected our understanding of both the absolute age of globular clusters and the uncertainties in this age estimate, and comment on the implications for cosmological models. This present... more
I review here recent developments which have affected our understanding of both the absolute age of globular clusters and the uncertainties in this age estimate, and comment on the implications for cosmological models. This present estimate is in agreement with the range long advocated by David Schramm. The major uncertainty in determining ages of globular clusers based upon the absolute magnitude of the main sequence turn-off remains the uncertainty in the distance to these clusters. Estimates of these distances have recently been upwardly revised due to Hipparcos parallax measurements, if one calibrates luminosities of main sequence stars. However, it is important to realize that at the present time, different distance measures are in disagreement. A recent estimate is that the oldest clusters are 11.5 ± 1.3 Gyr, implying a one-sided 95 distance measures are not incorporated. Incorporating more recent measures, including Hipparcos based statistical parallax measures, raises the me...
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Predicted rates for direct and indirect detection of dark-matter neutralinos depend in general on the spin content of the nucleon. Neutralinos that are predominantly B-ino are the likeliest candidates for detection via spin-dependent... more
Predicted rates for direct and indirect detection of dark-matter neutralinos depend in general on the spin content of the nucleon. Neutralinos that are predominantly B-ino are the likeliest candidates for detection via spin-dependent interactions. Uncertainties in the measured spin content of the nucleon may lead to dramatic uncertainties in the rates for detection of B-inos by scattering off of nuclei with unpaired neutrons. Rates for spin-dependent scattering of B-inos off of nuclei with unpaired protons are far more robust, as are rates for capture of B-inos in the Sun.
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The equations of electrodynamics are altered in the presence of a classical coherent axion dark matter background field, changing the dispersion relation for electromagnetic waves. Careful measurements of the frequency stability in... more
The equations of electrodynamics are altered in the presence of a classical coherent axion dark matter background field, changing the dispersion relation for electromagnetic waves. Careful measurements of the frequency stability in sensitive atomic clocks could in principle provide evidence for such a background for f_a > 10^7 GeV. Turning on a background magnetic field might enhance these effects in a controllable way, and interferometric measurements might also be useful for probing the time-varying photon dispersion relation that results from a coherent cosmic axion background.
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It is well known that in a de Sitter background all massless or light quantum fields will fluctuate with a magnitude which is proportional to the only dimensional pa-rameter governing the expansion, the stored energy density, ρ.... more
It is well known that in a de Sitter background all massless or light quantum fields will fluctuate with a magnitude which is proportional to the only dimensional pa-rameter governing the expansion, the stored energy density, ρ. Einstein’s Equa-tions relate this energy density to the expansion rate H, so that, for every scalar field φi, for modes with wavenumber k ≈ H 〈(δφi)2 〉 ≈ H 2
We incorporate all existing solar neutrino flux measurements and take solar model flux uncertainties into account in deriving global fits to parameter space for the MSW and vacuum solutions of the solar neutrino problem. 1
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The recognition that the cosmological constant may be non-zero forces us to reevaluate standard notions about the connection between geometry and the fate of our Universe. An open Universe can recollapse, and a closed Universe can expand... more
The recognition that the cosmological constant may be non-zero forces us to reevaluate standard notions about the connection between geometry and the fate of our Universe. An open Universe can recollapse, and a closed Universe can expand forever. As a corollary, we point out that there is no set of cosmological observations we can perform that will unambiguously allow us to determine what the ultimate destiny of the Universe will be.The traditional philosophy of General Relativity is that Geometry is Destiny. We teach undergraduates that the Universe can exist in one of three different geometries, open, closed and flat, and that once we determine which describes our Universe, this fixes its fate. In the past few years, however, several features of conventional wisdom in cosmology have fallen by the wayside. By 1995 it was already clear that fundamental observables, from the age of the Universe, to the baryon content, and the nature of large-scale structure, all independently pointed...
I review here recent developments which have affected our understanding of both the absolute age of globular clusters and the uncertainties in this age estimate, and comment on the implications for cosmological models. This present... more
I review here recent developments which have affected our understanding of both the absolute age of globular clusters and the uncertainties in this age estimate, and comment on the implications for cosmological models. This present estimate is in agreement with the range long advocated by David Schramm. The major uncertainty in determining ages of globular clusers based upon the absolute magnitude of the main sequence turn-off remains the uncertainty in the distance to these clusters. Estimates of these distances have recently been upwardly revised due to Hipparcos parallax measurements, if one calibrates luminosities of main sequence stars. However, it is important to realize that at the present time, different distance measures are in disagreement. A recent estimate is that the oldest clusters are 11.5 ±1.3 Gyr, implying a one-sided 95 % confidence level lower limit of 9.5 Gyr, if statistical parallax distance measures are not incorporated. Incorporating more recent measures, incl...
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Research Interests:
Page 1. QUANTUM MAN Richard Feynman's Life in Science LA WR KRAU Page 2. Quantum Man Page 3. published titles in the great discoveries series Sherwin B. Nuland The Doctors' Plague: Germs, Childbed Fever, and the ...
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Prologue Theyll Be Comin Round The Mountain Choose Your Poison To Be or Not to Be To Boldly Go If We Can Afford It A Cosmic Game of Golf There, and Back Again? Seeing Is Believing Gambling on the Galaxy The Restaurant at the End of the... more
Prologue Theyll Be Comin Round The Mountain Choose Your Poison To Be or Not to Be To Boldly Go If We Can Afford It A Cosmic Game of Golf There, and Back Again? Seeing Is Believing Gambling on the Galaxy The Restaurant at the End of the Universe Madonnas Universe May the Force Be with You Mad, Bad, and Dangerous to Know Its About Time All Good Things The Measure of a Man The Ghost in the Machine The Final Frontier? Epilogue.
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Low-Temperature Physics is unique in the breadth of topics covered in one text and the extent to which it emphasizes the interconnectedness of various subjects, which is frequently lost in this age of specialization. Christian Enss and... more
Low-Temperature Physics is unique in the breadth of topics covered in one text and the extent to which it emphasizes the interconnectedness of various subjects, which is frequently lost in this age of specialization. Christian Enss and Siegfried Hunklinger have written an extremely readable book that effectively treats most of the classical topics in a succinct yet reasonably complete manner; it also includes a survey chapter on experimental techniques. The book will be useful to students who are entering parts of the broader field of ...
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Will the universe continue to expand forever, reverse its expansion and begin to contract, or reach a delicately poised state where it simply persists forever? The answer depends on the amount and properties of matter in the universe, and... more
Will the universe continue to expand forever, reverse its expansion and begin to contract, or reach a delicately poised state where it simply persists forever? The answer depends on the amount and properties of matter in the universe, and that has given rise to one of the great paradoxes of modern cosmology: there is too little visible matter to account for the behavior we can see. Over ninety percent of the universe consists of missing mass or dark matter - what Lawrence Krauss, in his classic book, termed the fifth essence. In this new edition of The Fifth Essence, retitled Quintessence after the now widely accepted term for dark matter, Krauss shows how the dark matter problem is now connected with two of the hottest areas in recent cosmology: the fate of the universe and the cosmological constant. With a new introduction, epilogue, and chapter updates, Krauss updates his classic for 1999 and shares one of the most stunning discoveries of recent years: an anti-gravity force that explains recent observations of a permanently expanding universe.
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The flat matter dominated Universe that dominated cosmological model building for much of the past 20 years does not correspond to the Universe in which we live. This has profound implications both for our understanding of dark matter,... more
The flat matter dominated Universe that dominated cosmological model building for much of the past 20 years does not correspond to the Universe in which we live. This has profound implications both for our understanding of dark matter, and also for our understanding of the future of the Universe. I review recent developments here and present best fits for the current, sometimes crazy, values of the major measured fundamental cosmological parameters. (Invited review talk, 9th International Workshop on Neutrino Telescopes, Venice, March 2001. Note: this is an updated version of an article prepared for the proceedings of IDM2000 in York, UK.)
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... I hope that you enjoy this new version as much as I have enjoyed revisiting it. Lawrence M. Krauss Cleveland, Ohio November 2006 ... It is the joy of the theoretical physicist to discover them, and of the experimentalist to test their... more
... I hope that you enjoy this new version as much as I have enjoyed revisiting it. Lawrence M. Krauss Cleveland, Ohio November 2006 ... It is the joy of the theoretical physicist to discover them, and of the experimentalist to test their strength. In the end, they make physics accessible. ...