arXiv subjects
Publications and source records attributed to Janet M. Conrad.
Authors describe technical advances that will allow the IsoDAR cyclotron -- being developed for neutrino physics research -- to produce medical isotopes more efficiently than existing cyclotrons can.
The IsoDAR sterile-neutrino search requires a very high intensity neutrino source. For IsoDAR, this high intensity is produced using the high neutron flux from a 60 MeV, 10 mA proton beam striking a beryllium target that floods a sleeve of highly-enriched Li-7. Through neutron capture the Li-7 is transmuted to Li-8, which beta-decays giving the desired high neutrino flux for very-short baseline neutrino experiments. The target can be placed very close to can existing large neutrino detector, which is typically located deep underground to reduce backgrounds. With such a setup, it is necessary to design a shielding enclosure for the target to prevent neutrons from causing unacceptable activation of the rock walls close to the target. Various materials have been studied including steel to thermalize the high energy neutrons and two new types of concrete developed by Jefferson Laboratory, one very light with shredded plastic aggregate, and the other one enriched with high quantities of boron. The shielding is asymmetrical, having a larger thickness towards the detector in order to suppress the neutron and gamma background in the neutrino detector. Simulation results for rock activation and for detector backgrounds are presented.
The axion is a promising dark matter candidate, which was originally proposed to solve the strong-CP problem in particle physics. To date, the available parameter space for axion and axion-like particle dark matter is relatively unexplored, particularly at masses $m_a\lesssim1\,μ$eV. ABRACADABRA is a new experimental program to search for axion dark matter over a broad range of masses, $10^{-12}\lesssim m_a\lesssim10^{-6}$ eV. ABRACADABRA-10 cm is a small-scale prototype for a future detector that could be sensitive to the QCD axion. In this Letter, we present the first results from a 1 month search for axions with ABRACADABRA-10 cm. We find no evidence for axion-like cosmic dark matter and set 95% C.L. upper limits on the axion-photon coupling between $g_{aγγ}<1.4\times10^{-10}$ GeV$^{-1}$ and $g_{aγγ}<3.3\times10^{-9}$ GeV$^{-1}$ over the mass range $3.1\times10^{-10}$ eV - $8.3\times10^{-9}$ eV. These results are competitive with the most stringent astrophysical constraints in this mass range.
The past few years have seen a renewed interest in the search for light particle dark matter. ABRACADABRA is a new experimental program to search for axion dark matter over a broad range of masses, $10^{-12}\lesssim m_a\lesssim10^{-6}$ eV. ABRACADABRA-10 cm is a small-scale prototype for a future detector that could be sensitive to QCD axion couplings. In this paper, we present the details of the design, construction, and data analysis for the first axion dark matter search with the ABRACADABRA-10 cm detector. We include a detailed discussion of the statistical techniques used to extract the limit from the first result with an emphasis on creating a robust statistical footing for interpreting those limits.
Transitions between low-lying electron states in atoms of heavy elements lead to electromagnetic radiation with discrete energies between about 0.1~keV and 100~keV (x rays) that are characteristic of the element. Moseley's law --- an empirical relation first described by Moseley in 1913 which supported predictions of the then-new Bohr model of atomic energy levels while simultaneously identifying the integer atomic number $Z$ as the measure of nuclear charge --- predicts that the energy of these characteristic x rays scales as $Z^2$. The foundational nature of Moseley's experiment has led to the popularity of Moseley's law measurements in undergraduate advanced laboratory physics courses. We report here observations of deviations from Moseley's law in the characteristic $K_α$ x-ray emission of 13 elements ranging from $Z=29$ to $Z=92$. %: Cu, Rb, Mo, Ag, In, Ba, Tb, Ta, W, Pb, Au, Pt, and U. While following the square-law predictions of the Bohr model fairly well at low $Z$, the deviations become larger with increasing $Z$ (negligible probability of the Bohr model fitting data by a $χ^2$ test). We find that relativistic models of atomic structure are necessary to fit the full range of atomic numbers observed (probability value of $0.20$ for the relativistic Bohr-Sommerfeld model). As has been argued by previous authors, measurements of the relativistic deviations from Moseley's law are both pedagogically valuable at the advanced laboratory level and accessible with modern but modest apparatus. Here, we show that this pedagogical value can be be extended even further --- to higher $Z$ elements, where the effects are more dramatically observable --- using apparatus which is enhanced relative to more modest versions, but nevertheless still accessible for many teaching laboratories.
The CosmicWatch Desktop Muon Detector is a self-contained, hand-held cosmic ray muon detector that is valuable for astro/particle physics research applications and outreach. The material cost of each detector is under $100 and it takes a novice student approximately four hours to build their first detector. The detectors are powered via a USB connection and the data can either be recorded directly to a computer or to a microSD card. Arduino- and Python-based software is provided to operate the detector and an online application to plot the data in real-time. In this paper, we describe the various design features, evaluate the performance, and illustrate the detectors capabilities by providing several example measurements.
We study the phenomenology of neutrino decay together with neutrino oscillations in the context of eV-scale sterile neutrinos. We review the formalism of visible neutrino decay in which one of the decay products is a neutrino that potentially can be observed. We apply the formalism developed for decay to the recent sterile neutrino search performed by IceCube with TeV neutrinos. We show that for $ν_4$ lifetime $τ_4/m_4 \lesssim 10^{-16} {\rm eV^{-1}s}$, the interpretation of the high-energy IceCube analysis can be significantly changed.
Current and future neutrino experiments can be used to discover dark matter, not only in searches for dark matter annihilating to neutrinos, but also in scenarios where dark matter itself scatters off Standard Model particles in the detector. In this work, we study the sensitivity of different neutrino detectors to a class of models called boosted dark matter, in which a subdominant component of a dark sector acquires a large Lorentz boost today through annihilation of a dominant component in a dark matter-dense region, such as the galactic center or dwarf spheroidal galaxies. This analysis focuses on the sensitivity of different neutrino detectors, specifically the Cherenkov-based Super-K and the future argon-based DUNE to boosted dark matter that scatters off electrons. We study the dependence of the expected limits on the experimental features, such as energy threshold, volume and exposure in the limit of constant scattering amplitude. We highlight experiment-specific features that enable current and future neutrino experiments to be a powerful tool in finding signatures of boosted dark matter.
This paper describes an undergraduate-level physics project that incorporates various aspects of machine- and electronics-shop technical development. The desktop muon detector is a self-contained apparatus that employs plastic scintillator as a detection medium and a silicon photomultiplier for light collection. These detectors can be used in conjunction with the provided software to make interesting physics measurements. The total cost of each counter is approximately $100.
This document addresses concerns raised about possible limits, due to space charge, to the maximum H2+ ion beam current that can be injected into and accepted by a compact cyclotron. The discussion of the compact cyclotron is primarily within the context of the proposed DAEdALUS and IsoDAR neutrino experiments. These concerns are examined by the collaboration and addressed individually. While some of the concerns are valid, and present serious challenges to the proposed program, the collaboration sees no immediate showstoppers. However, some of the issues raised clearly need to be addressed carefully--analytically, through simulation, and through experiments. In this report, the matter is discussed, references are given to work already done and future plans are outlined.
The short baseline neutrino oscillation experiment, KPipe, is designed to perform a sensitive search for muon neutrino disappearance in the current global fit allowed regions for sterile neutrinos. KPipe is to be located at the Material Life Science Experimental Facility at J-PARC: the world's most intense source of 236~MeV, monoenergetic muon neutrinos. By measuring the $ν_μ$ charged current interaction rate along a 120~m long, 3~m diameter detector, KPipe can map out short baseline oscillations over an L/E of 0.14 to 0.64~m/MeV. Using a long, single detector to measure the $ν_μ$ interaction rate as a function of distance largely eliminates the systematic uncertainties associated with cross sections and fluxes. In this paper, we show that KPipe can cover the current global best fit to 5$σ$ after 3 years of running.
This technical report reviews the tests performed at the Best Cyclotron Systems, Inc. facility in regards to developing a cost effective ion source, beam line transport system, and acceleration system capable of high H$_2^+$ current output for the IsoDAR (Isotope Decay At Rest) experiment. We begin by outlining the requirements for the IsoDAR experiment then provide overview of the Versatile Ion Source, Low Energy Beam Transport system, spiral inflector, and cyclotron. The experimental measurements are then discussed and the results are compared with a thorough set of simulation studies. Of particular importance we note that the Versatile Ion Source (VIS) proved to be a reliable ion source capable of generating a large amount of H$_2^+$ current. The results suggest that with further upgrades, the VIS could potentially be a suitable candidate for IsoDAR. The conclusion outlines the key results from our tests and introduces the forthcoming work this technical report has motivated.
The preponderance of matter over antimatter in the early Universe, the dynamics of the supernova bursts that produced the heavy elements necessary for life and whether protons eventually decay --- these mysteries at the forefront of particle physics and astrophysics are key to understanding the early evolution of our Universe, its current state and its eventual fate. The Long-Baseline Neutrino Experiment (LBNE) represents an extensively developed plan for a world-class experiment dedicated to addressing these questions. LBNE is conceived around three central components: (1) a new, high-intensity neutrino source generated from a megawatt-class proton accelerator at Fermi National Accelerator Laboratory, (2) a near neutrino detector just downstream of the source, and (3) a massive liquid argon time-projection chamber deployed as a far detector deep underground at the Sanford Underground Research Facility. This facility, located at the site of the former Homestake Mine in Lead, South Dakota, is approximately 1,300 km from the neutrino source at Fermilab -- a distance (baseline) that delivers optimal sensitivity to neutrino charge-parity symmetry violation and mass ordering effects. This ambitious yet cost-effective design incorporates scalability and flexibility and can accommodate a variety of upgrades and contributions. With its exceptional combination of experimental configuration, technical capabilities, and potential for transformative discoveries, LBNE promises to be a vital facility for the field of particle physics worldwide, providing physicists from around the globe with opportunities to collaborate in a twenty to thirty year program of exciting science. In this document we provide a comprehensive overview of LBNE's scientific objectives, its place in the landscape of neutrino physics worldwide, the technologies it will incorporate and the capabilities it will possess.
This paper reviews the results of the LSND and MiniBooNE experiments. The primary goal of each experiment was to effect sensitive searches for neutrino oscillations in the mass region with $Δm^2 \sim 1$ eV$^2$. The two experiments are complementary, and so the comparison of results can bring additional information with respect to models with sterile neutrinos. Both experiments obtained evidence for $\bar ν_μ\rightarrow \bar ν_e$ oscillations, and MiniBooNE also observed a $ν_μ\rightarrow ν_e$ excess. In this paper, we review the design, analysis, and results from these experiments. We then consider the results within the global context of sterile neutrino oscillation models. The final data sets require a more extended model than the simple single sterile neutrino model imagined at the time that LSND drew to a close and MiniBooNE began. We show that there are apparent incompatibilities between data sets in models with two sterile neutrinos. However, these incompatibilities may be explained with variations within the systematic error. Overall, models with two (or three) sterile neutrinos seem to succeed in fitting the global data, and they make interesting predictions for future experiments.
DAEdALUS is an experiment to measure the CP-violation angle in the neutrino sector by producing multiple, intense beams of neutrinos from pion- and muon-decays-at-rest near an ultra-large water Cerenkov detector. In this talk, a design for the proposed Deep Underground Science and Engineering Laboratory in the U.S. was presented. DAEdALUS will be statistics-limited and have different systematic errors than long baseline CP-violation searches. When the data from both searches are combined, the sensitivity exceeds proton-driver designs. In this proceeding, we briefly describe one of several alternative cyclotron designs under consideration for DAEdALUS, as an example.
Neutrino scattering measurements offer a unique tool to probe the electroweak and strong interactions as described by the Standard Model (SM). Electroweak measurements are accessible through the comparison of neutrino neutral- and charged-current scattering. These measurements are complimentary to other electroweak measurements due to differences in the radiative corrections both within and outside the SM. Neutrino scattering measurements also provide a precise method for measuring the F_2(x,Q^2) and xF_3(x,Q^2 structure functions. The predicted Q^2 evolution can be used to test perturbative Quantum Chromodynamics as well as to measure the strong coupling constant, alpha _s, and the valence, sea, and gluon parton distributions. In addition, neutrino charm production, which can be determined from the observed dimuon events, allows the strange-quark sea to be investigated along with measurements of the CKM matrix element |V_{cd}| and the charm quark mass.