Showing 1–50 of 57 results for author: Milner, R

Realizing the Scientific Program with Polarized Ion Beams at EIC

Authors: Grigor Atoian, Nigel Buttimore, Giuseppe Ciullo, Ian Cloet, Marco Contalbrigo, Jaydeep Datta, Abhay Deshpande, Shubham Dutta, Oleg Eyser, Muhammad Farooq, Renee Fatemi, Ishara Fernando, Michael Finger, Wolfram Fischer, Dave Gaskell, Prakash Gautam, Ralf Gebel, Boxing Gou, Daoning Gu, Yoshitaka Hatta, Mohammad Hattawy, Volker Hejny, Kiel Hock, Georg Hoffstaetter, Haixin Huang , et al. (45 additional authors not shown)

Abstract: Polarized ion beams at the Electron Ion Collider are essential to address some of the most important open questions at the twenty-first century frontiers of understanding of the fundamental structure of matter. Here, we summarize the science case and identify polarized $^2$H, $^3$He, $^6$Li and $^7$Li ion beams as critical technology that will enable experiments which address the most important sc… ▽ More Polarized ion beams at the Electron Ion Collider are essential to address some of the most important open questions at the twenty-first century frontiers of understanding of the fundamental structure of matter. Here, we summarize the science case and identify polarized $^2$H, $^3$He, $^6$Li and $^7$Li ion beams as critical technology that will enable experiments which address the most important science. Further, we discuss the required ion polarimetry and spin manipulation in EIC. The current EIC accelerator design is presented. We identify a significant R\&D effort involving both national laboratories and universities that is required over about a decade to realize the polarized ion beams and estimate (based on previous experience) that it will require about 20 FTE over 10 years (or a total of about 200 FTE-years) of personnel, including graduate students, postdoctoral researchers, technicians and engineers. Attracting, educating and training a new generation of physicists in experimental spin techniques will be essential for successful realization. AI/ML is seen as having significant potential for both acceleration of R\&D and amplification of discovery in optimal realization of this unique quantum technology on a cutting-edge collider. The R\&D effort is synergistic with research in atomic physics and fusion energy science. △ Less

Submitted 12 October, 2025; originally announced October 2025.

Comments: 47 pages, 24 figures; submitted to Phys. Rev. C (PRC)

Experimental Scheme for Polarizing the Boron Nuclei

Authors: William R. Milner, Richard G. Milner

Abstract: Unravelling the internal structure of hadrons and nuclei in terms of the quarks and gluons of Quantum Chromodynamics is a central focus of current nuclear physics research. Directly observing gluonic states in the nucleus would be groundbreaking and is an objective of the future Electron-Ion Collider (EIC). Over thirty years ago, Jaffe and Manohar identified a new double-helicity flip structure fu… ▽ More Unravelling the internal structure of hadrons and nuclei in terms of the quarks and gluons of Quantum Chromodynamics is a central focus of current nuclear physics research. Directly observing gluonic states in the nucleus would be groundbreaking and is an objective of the future Electron-Ion Collider (EIC). Over thirty years ago, Jaffe and Manohar identified a new double-helicity flip structure function, directly sensitive to exotic gluons. They pointed out that this could be measured in inclusive high-energy electron scattering from a transversely polarized nuclear target with spin $I \ge 1$. Here, we identify the spin-3 nucleus boron-10 as a particularly interesting system to search for exotic gluons. Leveraging technical advances in atomic physics over the past decade, we outline an experimental scheme to directly optically pump a beam of stable boron atoms to polarize the nuclear spin. Technical challenges to realize a spin-polarized beam of boron-10 in the EIC are discussed. The proposed scheme will also polarize the $^{11}$B nucleus, which could significantly enhance the pB fusion cross section. △ Less

Submitted 6 August, 2025; originally announced August 2025.

Polarizing 3He via Metastability Exchange Optical Pumping Using a 1.2 mbar Sealed Cell at Magnetic Fields up to 5 T

Authors: Pushpa Pandey, Hao Lu, James Maxwell, James Brock, Christopher Keith, Xiaqing Li, Richard Milner, Dien Nguyen

Abstract: We report high nuclear polarization of 1.2 mbar 3He gas in a sealed cell in magnetic fields up to 5 T using Metastability Exchange Optical Pumping (MEOP). The creation of a highly polarized 3He gas target for use in the 5 T field of Jefferson Lab's CLAS12 spectrometer would enable new studies of spin-dependent asymmetries on the neutron. A systematic study was conducted to evaluate the effects of… ▽ More We report high nuclear polarization of 1.2 mbar 3He gas in a sealed cell in magnetic fields up to 5 T using Metastability Exchange Optical Pumping (MEOP). The creation of a highly polarized 3He gas target for use in the 5 T field of Jefferson Lab's CLAS12 spectrometer would enable new studies of spin-dependent asymmetries on the neutron. A systematic study was conducted to evaluate the effects of discharge intensity, pump laser power, and optical pumping transition schemes on nuclear polarization and pumping rates. Steady-state polarizations up to 86 % in magnetic fields between 2 and 5 T were achieved, with a discharge-on relaxation time of 898 s at 5 T. These results underscore the potential of MEOP for high-field applications in nuclear physics experiments. △ Less

Submitted 21 May, 2025; originally announced May 2025.

A High-Power Clock Laser Spectrally Tailored for High-Fidelity Quantum State Engineering

Authors: Lingfeng Yan, Stefan Lannig, William R. Milner, Max N. Frankel, Ben Lewis, Dahyeon Lee, Kyungtae Kim, Jun Ye

Abstract: Highly frequency-stable lasers are a ubiquitous tool for optical frequency metrology, precision interferometry, and quantum information science. While making a universally applicable laser is unrealistic, spectral noise can be tailored for specific applications. Here we report a high-power 698 nm clock laser with a maximum output of \SI{4}{W} and minimized frequency noise up to a few kHz Fourier f… ▽ More Highly frequency-stable lasers are a ubiquitous tool for optical frequency metrology, precision interferometry, and quantum information science. While making a universally applicable laser is unrealistic, spectral noise can be tailored for specific applications. Here we report a high-power 698 nm clock laser with a maximum output of \SI{4}{W} and minimized frequency noise up to a few kHz Fourier frequency, together with long-term instability of $3.5 \times 10^{-17}$ at one to thousands of seconds. The laser frequency noise is precisely characterized with atom-based spectral analysis that employs a pulse sequence designed to suppress sensitivity to intensity noise. This method provides universally applicable tunability of the spectral response and analysis of quantum sensors over a wide frequency range. With the optimized laser system characterized by this technique, we achieve an average single-qubit Clifford gate fidelity of up to $F_1^2 = 0.99964(3)$ when simultaneously driving 3000 optical qubits with a homogeneous Rabi frequency ranging from \SI{10}{Hz} to $\sim$$\SI{1}{kHz}$. This result represents the highest single optical-qubit gate fidelity for large number of atoms. △ Less

Submitted 29 July, 2025; v1 submitted 16 January, 2025; originally announced January 2025.

In situ imaging of the thermal de Broglie wavelength in an ultracold Bose gas

Authors: Jinggang Xiang, Enid Cruz-Colón, Candice C. Chua, William R. Milner, Julius de Hond, Jacob F. Fricke, Wolfgang Ketterle

Abstract: We report the first in situ observation of density fluctuations on the scale of the thermal de Broglie wavelength in an ultracold gas of bosons. Bunching of $^{87}$Rb atoms in a quasi two-dimensional system is observed by single-atom imaging using a quantum gas microscope. Compared to a classical ensemble, we observe a 30 percent enhancement of the second-order correlation function. We show the sp… ▽ More We report the first in situ observation of density fluctuations on the scale of the thermal de Broglie wavelength in an ultracold gas of bosons. Bunching of $^{87}$Rb atoms in a quasi two-dimensional system is observed by single-atom imaging using a quantum gas microscope. Compared to a classical ensemble, we observe a 30 percent enhancement of the second-order correlation function. We show the spatial and thermal dependence of these correlations. The reported method of detecting in situ correlations can be applied to interacting many-body systems and to the study of critical phenomena near phase transitions. △ Less

Submitted 13 November, 2024; originally announced November 2024.

Cryogenic photonic resonator with $10^{-17}$/s drift

Authors: Wei Zhang, William R. Milner, Jun Ye, Scott B. Papp

Abstract: Thermal noise is the predominant instability in the provision of ultrastable laser frequency, referencing to an optical cavity. Reducing the thermal-noise limit of a cavity means either making it larger to spread thermal fluctuations, reducing the sensitivity of the cavity to temperature, or lowering the temperature. We report on a compact photonic resonator made of solid fused silica that we cool… ▽ More Thermal noise is the predominant instability in the provision of ultrastable laser frequency, referencing to an optical cavity. Reducing the thermal-noise limit of a cavity means either making it larger to spread thermal fluctuations, reducing the sensitivity of the cavity to temperature, or lowering the temperature. We report on a compact photonic resonator made of solid fused silica that we cool in a cryogenic environment. We explore a null in the resonator frequency sensitivity due to the balance of thermal expansion and thermo-optic coefficients at a temperature of 9.5 K, enabling laser stabilization with a long-term frequency drift of 4 mHz/s on the 195 THz carrier. The robustness of fused silica to cryogenics, the capability for photonic design to mitigate thermal noise and drift, and operation at a modest 9.5 K temperature offer unique options for ultrastable laser systems. △ Less

Submitted 13 October, 2024; originally announced October 2024.

Coherent evolution of superexchange interaction in seconds long optical clock spectroscopy

Authors: William R. Milner, Stefan Lannig, Mikhail Mamaev, Lingfeng Yan, Anjun Chu, Ben Lewis, Max N. Frankel, Ross B. Hutson, Ana Maria Rey, Jun Ye

Abstract: Measurement science now connects strongly with engineering of quantum coherence, many-body states, and entanglement. To scale up the performance of an atomic clock using a degenerate Fermi gas loaded in a three-dimensional optical lattice, we must understand complex many-body Hamiltonians to ensure meaningful gains for metrological applications. In this work, we use a near unity filled Sr 3D latti… ▽ More Measurement science now connects strongly with engineering of quantum coherence, many-body states, and entanglement. To scale up the performance of an atomic clock using a degenerate Fermi gas loaded in a three-dimensional optical lattice, we must understand complex many-body Hamiltonians to ensure meaningful gains for metrological applications. In this work, we use a near unity filled Sr 3D lattice to study the effect of a tunable Fermi-Hubbard Hamiltonian. The clock laser introduces a spin-orbit coupling spiral phase and breaks the isotropy of superexchange interactions, changing the Heisenberg spin model into one exhibiting XXZ-type spin anisotropy. By tuning the lattice confinement and applying imaging spectroscopy we map out favorable atomic coherence regimes. With weak transverse confinement, both s- and p-wave interactions contribute to decoherence and atom loss, and their contributions can be balanced. At deep transverse confinement, we directly observe coherent superexchange interactions, tunable via on-site interaction and site-to-site energy shift, on the clock Ramsey fringe contrast over timescales of multiple seconds. This study provides a groundwork for using a 3D optical lattice clock to probe quantum magnetism and spin entanglement △ Less

Submitted 20 February, 2024; originally announced February 2024.

Measurement of $^3$He$^{++}$ Polarization at 5.3 MeV via Scattering with an Unpolarized $^4$He Target

Authors: Charles Epstein, Richard Milner

Abstract: Since 2012, a BNL-MIT collaboration has worked to develop a polarized $^3$He ion source for the Relativistic Heavy Ion Collider (RHIC) using the existing Electron Beam Ionization Source (EBIS). $^3$He atoms are polarized using optical pumping at high field and injected as neutral atoms into the EBIS. A critical issue is the demonstration that the polarization of the extracted $^3$He$^{++}$ ions fr… ▽ More Since 2012, a BNL-MIT collaboration has worked to develop a polarized $^3$He ion source for the Relativistic Heavy Ion Collider (RHIC) using the existing Electron Beam Ionization Source (EBIS). $^3$He atoms are polarized using optical pumping at high field and injected as neutral atoms into the EBIS. A critical issue is the demonstration that the polarization of the extracted $^3$He$^{++}$ ions from the source is high. In 2014, a concept to measure the nuclear polarization was developed in this paper. Since then, the development of the polarized $^3$He ion source has progressed, the polarimeter is under construction, and the demonstration experiment is expected to take place in the next several years. △ Less

Submitted 30 July, 2023; originally announced August 2023.

Metastability exchange optical pumping of $^3$He at low pressure and high magnetic field

Authors: X. Li, J. D. Maxwell, D. Nguyen, J. Brock, C. D. Keith, R. G. Milner, X. Wei

Abstract: Systematic studies on metastability exchange optical pumping of $^3$He nuclei have been performed at Jefferson Lab using a 1-torr sealed cell at magnetic fields from 2 to 4 T. The effects of the discharge intensity, pump laser power, and pumping transition schemes on achievable nuclear polarization and pumping rate have been investigated. A maximum steady-state nuclear polarization of about 75% ha… ▽ More Systematic studies on metastability exchange optical pumping of $^3$He nuclei have been performed at Jefferson Lab using a 1-torr sealed cell at magnetic fields from 2 to 4 T. The effects of the discharge intensity, pump laser power, and pumping transition schemes on achievable nuclear polarization and pumping rate have been investigated. A maximum steady-state nuclear polarization of about 75% has been obtained. This work provides a baseline for the development of the novel polarized $^3$He target for CLAS12 at Jefferson Lab. △ Less

Submitted 29 February, 2024; v1 submitted 10 July, 2023; originally announced July 2023.

Journal ref: Nucl. Instrum. Meth. A 1057, 168792 (2023)

Optically Pumped Polarized $^3$He$^{++}$ Ion Source Development for RHIC/EIC

Authors: A. Zelenski, G. Atoian, E. Beebe, S. Ikeda, T. Kanesue, S. Kondrashev, J. Maxwell, R. Milner, M. Musgrave, M. Okamura, A. A. Poblaguev, D. Raparia, J. Ritter, A. Sukhanov, S. Trabocchi

Abstract: The proposed polarized $^3$He$^{++}$ acceleration in RHIC and the future Electron-Ion Collider will require about $2\times10^{11}$ ions in the source pulse. A new technique had been proposed for production of high intensity polarized $^3$He$^{++}$ ion beams. It is based on ionization and accumulation of the $^3$He gas (polarized by metastability-exchange optical pumping and in the 5 T high magneti… ▽ More The proposed polarized $^3$He$^{++}$ acceleration in RHIC and the future Electron-Ion Collider will require about $2\times10^{11}$ ions in the source pulse. A new technique had been proposed for production of high intensity polarized $^3$He$^{++}$ ion beams. It is based on ionization and accumulation of the $^3$He gas (polarized by metastability-exchange optical pumping and in the 5 T high magnetic field) in the existing Electron Beam Ion Source (EBIS). A novel $^3$He cryogenic purification and storage technique was developed to provide the required gas purity. An original gas refill and polarized $^3$He gas injection to the EBIS long drift tubes, (which serves as the storage cell) were developed to ensure polarization preservation. An infrared laser system for optical pumping and polarization measurements in the high 3--5 T field has been developed. The $^3$He polarization 80--85\% (and sufficiently long $\sim30$ min relaxation time) was obtained in the \lq\lq{open}\rq\rq\ cell configuration with refilling valve tube inlet and isolation valve closed. The development of the spin-rotator and $^3$He $^4$He absolute nuclear polarimeter at 6 MeV $^3$He$^{++}$ beam energy is also presented. △ Less

Submitted 7 July, 2023; v1 submitted 18 March, 2023; originally announced March 2023.

Comments: 9 pages, 11 figures

Journal ref: A. Zelenski, G. Atoian, E. Beebe, et. al,S. Ikeda, Optically pumped polarized 3He++ ion source development for RHIC/EIC, Nuclear Instr. Meth. A 1055 (2023) 168494

Realizing spin squeezing with Rydberg interactions in a programmable optical clock

Authors: William J. Eckner, Nelson Darkwah Oppong, Alec Cao, Aaron W. Young, William R. Milner, John M. Robinson, Jun Ye, Adam M. Kaufman

Abstract: Neutral-atom arrays trapped in optical potentials are a powerful platform for studying quantum physics, combining precise single-particle control and detection with a range of tunable entangling interactions. For example, these capabilities have been leveraged for state-of-the-art frequency metrology as well as microscopic studies of entangled many-particle states. In this work, we combine these a… ▽ More Neutral-atom arrays trapped in optical potentials are a powerful platform for studying quantum physics, combining precise single-particle control and detection with a range of tunable entangling interactions. For example, these capabilities have been leveraged for state-of-the-art frequency metrology as well as microscopic studies of entangled many-particle states. In this work, we combine these applications to realize spin squeezing - a widely studied operation for producing metrologically useful entanglement - in an optical atomic clock based on a programmable array of interacting optical qubits. In this first demonstration of Rydberg-mediated squeezing with a neutral-atom optical clock, we generate states that have almost 4 dB of metrological gain. Additionally, we perform a synchronous frequency comparison between independent squeezed states and observe a fractional frequency stability of $1.087(1)\times 10^{-15}$ at one-second averaging time, which is 1.94(1) dB below the standard quantum limit, and reaches a fractional precision at the $10^{-17}$ level during a half-hour measurement. We further leverage the programmable control afforded by optical tweezer arrays to apply local phase shifts in order to explore spin squeezing in measurements that operate beyond the relative coherence time with the optical local oscillator. The realization of this spin-squeezing protocol in a programmable atom-array clock opens the door to a wide range of quantum-information inspired techniques for optimal phase estimation and Heisenberg-limited optical atomic clocks. △ Less

Submitted 23 July, 2023; v1 submitted 14 March, 2023; originally announced March 2023.

Comments: 13 pages, 4 figures; Supplementary Information

Journal ref: Nature 621, 734 (2023)

Observation of mHz-level cooperative Lamb shifts in an optical atomic clock

Authors: Ross B. Hutson, William R. Milner, Lingfeng Yan, Jun Ye, Christian Sanner

Abstract: We report on the direct observation of resonant electric dipole-dipole interactions in a cubic array of atoms in the many-excitation limit. The interactions, mediated by single-atom couplings to the shared electromagnetic vacuum, are shown to produce spatially-dependent cooperative Lamb shifts when spectroscopically interrogating the mHz-wide optical clock transition in strontium-87. We show that… ▽ More We report on the direct observation of resonant electric dipole-dipole interactions in a cubic array of atoms in the many-excitation limit. The interactions, mediated by single-atom couplings to the shared electromagnetic vacuum, are shown to produce spatially-dependent cooperative Lamb shifts when spectroscopically interrogating the mHz-wide optical clock transition in strontium-87. We show that the ensemble-averaged shifts can be suppressed below the level of evaluated systematic uncertainties for state-of-the-art optical atomic clocks. Additionally, we demonstrate that excitation of the atomic dipoles near a Bragg angle can enhance these effects by nearly an order of magnitude compared to non-resonant geometries. Given the remarkable precision of frequency measurements and the high accuracy of the modeled response, our work demonstrates that such a clock is a novel platform for studies of the quantum many-body physics of spins with long-range interactions mediated by propagating photons. △ Less

Submitted 9 March, 2023; originally announced March 2023.

Two-Photon EXchange -- TPEX

Authors: R. Alarcon, R. Beck, J. C. Bernauer, M. Broering, E. Cline, B. Dongwi, I. Fernando, M. Finger, M. Finger Jr., I. Friščić, T. Gautam, D. K. Hasell, O. Hen, J. Holmes, T. Horn, E. Ihloff, R. Johnston, J. Kelsey, M. Kohl, T. Kutz, I. Lavrukhin, S. Lee, W. Lorenzon, F. Maas, H. Merkel , et al. (12 additional authors not shown)

Abstract: We propose a new measurement of the ratio of positron-proton to electron-proton, elastic scattering at DESY to determine the contributions beyond single-photon exchange, which are essential to the QED description of the most fundamental process in hadronic physics. A 20~cm long liquid hydrogen target together with the extracted beam from the DESY synchrotron would yield an average luminosity of… ▽ More We propose a new measurement of the ratio of positron-proton to electron-proton, elastic scattering at DESY to determine the contributions beyond single-photon exchange, which are essential to the QED description of the most fundamental process in hadronic physics. A 20~cm long liquid hydrogen target together with the extracted beam from the DESY synchrotron would yield an average luminosity of $2.12\times10^{35}$~cm$^{-2}\cdot$s$^{-1}\cdot$sr$^{-1}$ ($\sim200$ times the luminosity achieved by OLYMPUS). A commissioning run at 2 GeV followed by measurements at 3 GeV would provide new data up to $Q^2=4.6$~(GeV/$c$)$^2$ (twice the range of current measurements). Lead tungstate calorimeters would be used to detect the scattered leptons at polar angles of $30^\circ$, $50^\circ$, $70^\circ$, $90^\circ$, and $110^\circ$. The measurements could be scheduled to not interfere with the operation of PETRA. We present rate estimates and simulations for the planned measurements including background considerations. Initial measurements at the DESY test beam facility using prototype lead tungstate calorimeters in 2019, 2021, and 2022 were made to check the Monte Carlo simulations and the performance of the calorimeters. These tests also investigated different readout schemes (triggered and streaming). Various upgrades are possible to shorten the running time and to make higher beam energies and thus greater $Q^2$ ranges accessible. △ Less

Submitted 11 January, 2023; originally announced January 2023.

Comments: 45 pages, 43 figures, submitted to the DESY PRC

High-fidelity imaging of a band insulator in a three-dimensional optical lattice clock

Authors: W. R. Milner, L. Yan, R. B. Hutson, C. Sanner, J. Ye

Abstract: We report on the observation of a high-density, band insulating state in a three-dimensional optical lattice clock. Filled with a nuclear-spin polarized degenerate Fermi gas of 87Sr, the 3D lattice has one atom per site in the ground motional state, thus guarding against frequency shifts due to contact interactions. At this high density where the average distance between atoms is comparable to the… ▽ More We report on the observation of a high-density, band insulating state in a three-dimensional optical lattice clock. Filled with a nuclear-spin polarized degenerate Fermi gas of 87Sr, the 3D lattice has one atom per site in the ground motional state, thus guarding against frequency shifts due to contact interactions. At this high density where the average distance between atoms is comparable to the probe wavelength, standard imaging techniques suffer from large systematic errors. To spatially probe frequency shifts in the clock and measure thermodynamic properties of this system, accurate imaging techniques at high optical depths are required. Using a combination of highly saturated fluorescence and absorption imaging, we confirm the density distribution in our 3D optical lattice in agreement with a single spin band insulating state. Combining our clock platform with this high filling fraction opens the door to studying new classes of long-lived, many-body states arising from dipolar interactions. △ Less

Submitted 9 January, 2023; originally announced January 2023.

Comments: 10 pages, 8 figures

Frequency stability of cryogenic silicon cavities with semiconductor crystalline coatings

Authors: Dhruv Kedar, Jialiang Yu, Eric Oelker, Alexander Staron, William R. Milner, John M. Robinson, Thomas Legero, Fritz Riehle, Uwe Sterr, Jun Ye

Abstract: State-of-the-art optical oscillators employing cryogenic reference cavities are limited in performance by the Brownian thermal noise associated with the mechanical dissipation of the mirror coatings. Recently, crystalline Al$_{1-x}$Ga$_{x}$As/GaAs coatings have emerged as a promising candidate for improved coating thermal noise. We present measurements of the frequency noise of two fully crystalli… ▽ More State-of-the-art optical oscillators employing cryogenic reference cavities are limited in performance by the Brownian thermal noise associated with the mechanical dissipation of the mirror coatings. Recently, crystalline Al$_{1-x}$Ga$_{x}$As/GaAs coatings have emerged as a promising candidate for improved coating thermal noise. We present measurements of the frequency noise of two fully crystalline cryogenic reference cavities with Al$_{0.92}$Ga$_{0.08}$As/GaAs optical coatings. We report on previously unmeasured birefringent noise associated with anti-correlated frequency fluctuations between the polarization modes of the crystalline coatings, and identify variables that affect its magnitude. Comparing the birefringent noise between the two cryogenic reference cavities reveals a phenomenological set of scalings with intracavity power and mode area. We implement an interrogation scheme that cancels this noise by simultaneous probing of both polarization modes. The residual noise remaining after this cancellation is larger than both cavities thermal noise limits, but still lower than the instabilities previously measured on equivalent resonators with dielectric coatings. Though the source of these novel noise mechanisms is unclear, we demonstrate that crystalline coatings can provide stability and sensitivity competitive with resonators employing dielectric coatings. △ Less

Submitted 26 October, 2022; originally announced October 2022.

Comments: 10 pages, 6 figures

Snowmass'21 Accelerator Frontier Report

Authors: S. Gourlay, T. Raubenheimer, V. Shiltsev, G. Arduini, R. Assmann, C. Barbier, M. Bai, S. Belomestnykh, S. Bermudez, P. Bhat, A. Faus-Golfe, J. Galambos, C. Geddes, G. Hoffstaetter, M. Hogan, Z. Huang, M. Lamont, D. Li, S. Lund, R. Milner, P. Musumeci, E. Nanni, M. Palmer, N. Pastrone, F. Pellemoine , et al. (13 additional authors not shown)

Abstract: In 2020-2022, extensive discussions and deliberations have taken place in corresponding topical working groups of the Snowmass Accelerator Frontier (AF) and in numerous joint meetings with other Frontiers, Snowmass-wide meetings, a series of Colloquium-style Agoras, cross-Frontier Forums on muon and electron-positron colliders and the collider Implementation Task Force (ITF). The outcomes of these… ▽ More In 2020-2022, extensive discussions and deliberations have taken place in corresponding topical working groups of the Snowmass Accelerator Frontier (AF) and in numerous joint meetings with other Frontiers, Snowmass-wide meetings, a series of Colloquium-style Agoras, cross-Frontier Forums on muon and electron-positron colliders and the collider Implementation Task Force (ITF). The outcomes of these activities are summarized in this Accelerator Frontier report. △ Less

Submitted 17 November, 2022; v1 submitted 28 September, 2022; originally announced September 2022.

Comments: contribution to Snowmass'21, v.2 (final)

Accelerators for Rare Processes and Physics Beyond Colliders: Report of the AF5 Topical Group to Snowmass 2021

Authors: E. Prebys, M. Lamont, R. Milner

Abstract: This report summarizes the findings of the AF5 Topical Subgroup to Snowmass 2021, which investigated accelerators for rare processes and physics beyond colliders. The report focuses primarily on opportunities for dark sector searches and the need for coordinated development of the Fermilab experimental program for PIP-II and beyond. In addition, a number of other physics opportunities are cataloge… ▽ More This report summarizes the findings of the AF5 Topical Subgroup to Snowmass 2021, which investigated accelerators for rare processes and physics beyond colliders. The report focuses primarily on opportunities for dark sector searches and the need for coordinated development of the Fermilab experimental program for PIP-II and beyond. In addition, a number of other physics opportunities are cataloged and suggestions for synergistic R & D opportunities with various areas of technological development are discussed. △ Less

Submitted 13 September, 2022; originally announced September 2022.

Design of the ECCE Detector for the Electron Ion Collider

Authors: J. K. Adkins, Y. Akiba, A. Albataineh, M. Amaryan, I. C. Arsene, C. Ayerbe Gayoso, J. Bae, X. Bai, M. D. Baker, M. Bashkanov, R. Bellwied, F. Benmokhtar, V. Berdnikov, J. C. Bernauer, F. Bock, W. Boeglin, M. Borysova, E. Brash, P. Brindza, W. J. Briscoe, M. Brooks, S. Bueltmann, M. H. S. Bukhari, A. Bylinkin, R. Capobianco , et al. (259 additional authors not shown)

Abstract: The EIC Comprehensive Chromodynamics Experiment (ECCE) detector has been designed to address the full scope of the proposed Electron Ion Collider (EIC) physics program as presented by the National Academy of Science and provide a deeper understanding of the quark-gluon structure of matter. To accomplish this, the ECCE detector offers nearly acceptance and energy coverage along with excellent track… ▽ More The EIC Comprehensive Chromodynamics Experiment (ECCE) detector has been designed to address the full scope of the proposed Electron Ion Collider (EIC) physics program as presented by the National Academy of Science and provide a deeper understanding of the quark-gluon structure of matter. To accomplish this, the ECCE detector offers nearly acceptance and energy coverage along with excellent tracking and particle identification. The ECCE detector was designed to be built within the budget envelope set out by the EIC project while simultaneously managing cost and schedule risks. This detector concept has been selected to be the basis for the EIC project detector. △ Less

Submitted 20 July, 2024; v1 submitted 6 September, 2022; originally announced September 2022.

Comments: 34 pages, 30 figures, 9 tables

Report number: JLAB-PHY-24-4124

Detector Requirements and Simulation Results for the EIC Exclusive, Diffractive and Tagging Physics Program using the ECCE Detector Concept

Authors: A. Bylinkin, C. T. Dean, S. Fegan, D. Gangadharan, K. Gates, S. J. D. Kay, I. Korover, W. B. Li, X. Li, R. Montgomery, D. Nguyen, G. Penman, J. R. Pybus, N. Santiesteban, R. Trotta, A. Usman, M. D. Baker, J. Frantz, D. I. Glazier, D. W. Higinbotham, T. Horn, J. Huang, G. Huber, R. Reed, J. Roche , et al. (258 additional authors not shown)

Abstract: This article presents a collection of simulation studies using the ECCE detector concept in the context of the EIC's exclusive, diffractive, and tagging physics program, which aims to further explore the rich quark-gluon structure of nucleons and nuclei. To successfully execute the program, ECCE proposed to utilize the detecter system close to the beamline to ensure exclusivity and tag ion beam/fr… ▽ More This article presents a collection of simulation studies using the ECCE detector concept in the context of the EIC's exclusive, diffractive, and tagging physics program, which aims to further explore the rich quark-gluon structure of nucleons and nuclei. To successfully execute the program, ECCE proposed to utilize the detecter system close to the beamline to ensure exclusivity and tag ion beam/fragments for a particular reaction of interest. Preliminary studies confirmed the proposed technology and design satisfy the requirements. The projected physics impact results are based on the projected detector performance from the simulation at 10 or 100 fb^-1 of integrated luminosity. Additionally, a few insights on the potential 2nd Interaction Region can (IR) were also documented which could serve as a guidepost for the future development of a second EIC detector. △ Less

Submitted 6 March, 2023; v1 submitted 30 August, 2022; originally announced August 2022.

Searching for New Physics with DarkLight at the ARIEL Electron-Linac

Authors: The DarkLight Collaboration, E. Cline, R. Corliss, J. C. Bernauer, R. Alarcon, R. Baartman, S. Benson, J. Bessuille, D. Ciarniello, A. Christopher, A. Colon, W. Deconinck, K. Dehmelt, A. Deshpande, J. Dilling, D. H. Dongwi, P. Fisher, T. Gautam, M. Gericke, D. Hasell, M. Hasinoff, E. Ihloff, R. Johnston, R. Kanungo, J. Kelsey , et al. (21 additional authors not shown)

Abstract: The search for a dark photon holds considerable interest in the physics community. Such a force carrier would begin to illuminate the dark sector. Many experiments have searched for such a particle, but so far it has proven elusive. In recent years the concept of a low mass dark photon has gained popularity in the physics community. Of particular recent interest is the $^8$Be and $^4$He anomaly, w… ▽ More The search for a dark photon holds considerable interest in the physics community. Such a force carrier would begin to illuminate the dark sector. Many experiments have searched for such a particle, but so far it has proven elusive. In recent years the concept of a low mass dark photon has gained popularity in the physics community. Of particular recent interest is the $^8$Be and $^4$He anomaly, which could be explained by a new fifth force carrier with a mass of 17 MeV/$c^2$. The proposed DarkLight experiment would search for this potential low mass force carrier at ARIEL in the 10-20 MeV e$^+$e$^-$ invariant mass range. This proceeding will focus on the experimental design and physics case of the DarkLight experiment. △ Less

Submitted 14 August, 2022; v1 submitted 8 August, 2022; originally announced August 2022.

Comments: 7 pages, 4 figures, to be submitted as part of the proceedings on "New Scientific Opportunities with the TRIUMF ARIEL e-linac"

Open Heavy Flavor Studies for the ECCE Detector at the Electron Ion Collider

Authors: X. Li, J. K. Adkins, Y. Akiba, A. Albataineh, M. Amaryan, I. C. Arsene, C. Ayerbe Gayoso, J. Bae, X. Bai, M. D. Baker, M. Bashkanov, R. Bellwied, F. Benmokhtar, V. Berdnikov, J. C. Bernauer, F. Bock, W. Boeglin, M. Borysova, E. Brash, P. Brindza, W. J. Briscoe, M. Brooks, S. Bueltmann, M. H. S. Bukhari, A. Bylinkin , et al. (262 additional authors not shown)

Abstract: The ECCE detector has been recommended as the selected reference detector for the future Electron-Ion Collider (EIC). A series of simulation studies have been carried out to validate the physics feasibility of the ECCE detector. In this paper, detailed studies of heavy flavor hadron and jet reconstruction and physics projections with the ECCE detector performance and different magnet options will… ▽ More The ECCE detector has been recommended as the selected reference detector for the future Electron-Ion Collider (EIC). A series of simulation studies have been carried out to validate the physics feasibility of the ECCE detector. In this paper, detailed studies of heavy flavor hadron and jet reconstruction and physics projections with the ECCE detector performance and different magnet options will be presented. The ECCE detector has enabled precise EIC heavy flavor hadron and jet measurements with a broad kinematic coverage. These proposed heavy flavor measurements will help systematically study the hadronization process in vacuum and nuclear medium especially in the underexplored kinematic region. △ Less

Submitted 23 July, 2022; v1 submitted 21 July, 2022; originally announced July 2022.

Comments: Open heavy flavor studies with the EIC reference detector design by the ECCE consortium. 11 pages, 11 figures, to be submitted to the Nuclear Instruments and Methods A

Report number: LANL report number: LA-UR-22-27181

Exclusive J/$ψ$ Detection and Physics with ECCE

Authors: X. Li, J. K. Adkins, Y. Akiba, A. Albataineh, M. Amaryan, I. C. Arsene, C. Ayerbe Gayoso, J. Bae, X. Bai, M. D. Baker, M. Bashkanov, R. Bellwied, F. Benmokhtar, V. Berdnikov, J. C. Bernauer, F. Bock, W. Boeglin, M. Borysova, E. Brash, P. Brindza, W. J. Briscoe, M. Brooks, S. Bueltmann, M. H. S. Bukhari, A. Bylinkin , et al. (262 additional authors not shown)

Abstract: Exclusive heavy quarkonium photoproduction is one of the most popular processes in EIC, which has a large cross section and a simple final state. Due to the gluonic nature of the exchange Pomeron, this process can be related to the gluon distributions in the nucleus. The momentum transfer dependence of this process is sensitive to the interaction sites, which provides a powerful tool to probe the… ▽ More Exclusive heavy quarkonium photoproduction is one of the most popular processes in EIC, which has a large cross section and a simple final state. Due to the gluonic nature of the exchange Pomeron, this process can be related to the gluon distributions in the nucleus. The momentum transfer dependence of this process is sensitive to the interaction sites, which provides a powerful tool to probe the spatial distribution of gluons in the nucleus. Recently the problem of the origin of hadron mass has received lots of attention in determining the anomaly contribution $M_{a}$. The trace anomaly is sensitive to the gluon condensate, and exclusive production of quarkonia such as J/$ψ$ and $Υ$ can serve as a sensitive probe to constrain it. In this paper, we present the performance of the ECCE detector for exclusive J/$ψ$ detection and the capability of this process to investigate the above physics opportunities with ECCE. △ Less

Submitted 21 July, 2022; originally announced July 2022.

Comments: 11 pages, 14 figures, 1 table

Design and Simulated Performance of Calorimetry Systems for the ECCE Detector at the Electron Ion Collider

Authors: F. Bock, N. Schmidt, P. K. Wang, N. Santiesteban, T. Horn, J. Huang, J. Lajoie, C. Munoz Camacho, J. K. Adkins, Y. Akiba, A. Albataineh, M. Amaryan, I. C. Arsene, C. Ayerbe Gayoso, J. Bae, X. Bai, M. D. Baker, M. Bashkanov, R. Bellwied, F. Benmokhtar, V. Berdnikov, J. C. Bernauer, W. Boeglin, M. Borysova, E. Brash , et al. (263 additional authors not shown)

Abstract: We describe the design and performance the calorimeter systems used in the ECCE detector design to achieve the overall performance specifications cost-effectively with careful consideration of appropriate technical and schedule risks. The calorimeter systems consist of three electromagnetic calorimeters, covering the combined pseudorapdity range from -3.7 to 3.8 and two hadronic calorimeters. Key… ▽ More We describe the design and performance the calorimeter systems used in the ECCE detector design to achieve the overall performance specifications cost-effectively with careful consideration of appropriate technical and schedule risks. The calorimeter systems consist of three electromagnetic calorimeters, covering the combined pseudorapdity range from -3.7 to 3.8 and two hadronic calorimeters. Key calorimeter performances which include energy and position resolutions, reconstruction efficiency, and particle identification will be presented. △ Less

Submitted 19 July, 2022; originally announced July 2022.

Comments: 19 pages, 22 figures, 5 tables

AI-assisted Optimization of the ECCE Tracking System at the Electron Ion Collider

Authors: C. Fanelli, Z. Papandreou, K. Suresh, J. K. Adkins, Y. Akiba, A. Albataineh, M. Amaryan, I. C. Arsene, C. Ayerbe Gayoso, J. Bae, X. Bai, M. D. Baker, M. Bashkanov, R. Bellwied, F. Benmokhtar, V. Berdnikov, J. C. Bernauer, F. Bock, W. Boeglin, M. Borysova, E. Brash, P. Brindza, W. J. Briscoe, M. Brooks, S. Bueltmann , et al. (258 additional authors not shown)

Abstract: The Electron-Ion Collider (EIC) is a cutting-edge accelerator facility that will study the nature of the "glue" that binds the building blocks of the visible matter in the universe. The proposed experiment will be realized at Brookhaven National Laboratory in approximately 10 years from now, with detector design and R&D currently ongoing. Notably, EIC is one of the first large-scale facilities to… ▽ More The Electron-Ion Collider (EIC) is a cutting-edge accelerator facility that will study the nature of the "glue" that binds the building blocks of the visible matter in the universe. The proposed experiment will be realized at Brookhaven National Laboratory in approximately 10 years from now, with detector design and R&D currently ongoing. Notably, EIC is one of the first large-scale facilities to leverage Artificial Intelligence (AI) already starting from the design and R&D phases. The EIC Comprehensive Chromodynamics Experiment (ECCE) is a consortium that proposed a detector design based on a 1.5T solenoid. The EIC detector proposal review concluded that the ECCE design will serve as the reference design for an EIC detector. Herein we describe a comprehensive optimization of the ECCE tracker using AI. The work required a complex parametrization of the simulated detector system. Our approach dealt with an optimization problem in a multidimensional design space driven by multiple objectives that encode the detector performance, while satisfying several mechanical constraints. We describe our strategy and show results obtained for the ECCE tracking system. The AI-assisted design is agnostic to the simulation framework and can be extended to other sub-detectors or to a system of sub-detectors to further optimize the performance of the EIC detector. △ Less

Submitted 19 May, 2022; v1 submitted 18 May, 2022; originally announced May 2022.

Comments: 16 pages, 18 figures, 2 appendices, 3 tables

Scientific Computing Plan for the ECCE Detector at the Electron Ion Collider

Authors: J. C. Bernauer, C. T. Dean, C. Fanelli, J. Huang, K. Kauder, D. Lawrence, J. D. Osborn, C. Paus, J. K. Adkins, Y. Akiba, A. Albataineh, M. Amaryan, I. C. Arsene, C. Ayerbe Gayoso, J. Bae, X. Bai, M. D. Baker, M. Bashkanov, R. Bellwied, F. Benmokhtar, V. Berdnikov, F. Bock, W. Boeglin, M. Borysova, E. Brash , et al. (256 additional authors not shown)

Abstract: The Electron Ion Collider (EIC) is the next generation of precision QCD facility to be built at Brookhaven National Laboratory in conjunction with Thomas Jefferson National Laboratory. There are a significant number of software and computing challenges that need to be overcome at the EIC. During the EIC detector proposal development period, the ECCE consortium began identifying and addressing thes… ▽ More The Electron Ion Collider (EIC) is the next generation of precision QCD facility to be built at Brookhaven National Laboratory in conjunction with Thomas Jefferson National Laboratory. There are a significant number of software and computing challenges that need to be overcome at the EIC. During the EIC detector proposal development period, the ECCE consortium began identifying and addressing these challenges in the process of producing a complete detector proposal based upon detailed detector and physics simulations. In this document, the software and computing efforts to produce this proposal are discussed; furthermore, the computing and software model and resources required for the future of ECCE are described. △ Less

Submitted 17 May, 2022; originally announced May 2022.

Journal ref: NIMA 1047, 167859 (2023)

A Concept for Polarized $^3$He Targets for High Luminosity Scattering Experiments in High Magnetic Field Environments

Authors: James Maxwell, Richard Milner

Abstract: We present the conceptual design of a polarized $^3$He target to be used for high luminosity scattering experiments within high magnetic field environments. This two-cell target will take advantage of advancements in optical pumping techniques at high magnetic field to create 60% longitudinally polarized $^3$He gas in a pumping cell within a uniform magnetic field above 1 T. By transferring the po… ▽ More We present the conceptual design of a polarized $^3$He target to be used for high luminosity scattering experiments within high magnetic field environments. This two-cell target will take advantage of advancements in optical pumping techniques at high magnetic field to create 60% longitudinally polarized $^3$He gas in a pumping cell within a uniform magnetic field above 1 T. By transferring the polarized gas to cryogenic target cell, the gas density is increased to create a target thickness suitable for high luminosity applications. We discuss the general design of this scheme, and plans for its application in Jefferson Lab's CLAS12 detector. △ Less

Submitted 11 June, 2021; originally announced June 2021.

Comments: arXiv admin note: substantial text overlap with arXiv:1911.06650

Report number: JLAB-PHY-21-3421

Operation and characterization of a windowless gas jet target in high-intensity electron beams

Authors: B. S. Schlimme, S. Aulenbacher, P. Brand, M. Littich, Y. Wang, P. Achenbach, M. Ball, J. C. Bernauer, M. Biroth, D. Bonaventura, D. Bosnar, S. Caiazza, M. Christmann, E. Cline, A. Denig, M. O. Distler, L. Doria, P. Eckert, A. Esser, I. Friščić, S. Gagneur, J. Geimer, S. Grieser, P. Gülker, P. Herrmann , et al. (32 additional authors not shown)

Abstract: A cryogenic supersonic gas jet target was developed for the MAGIX experiment at the high-intensity electron accelerator MESA. It will be operated as an internal, windowless target in the energy-recovering recirculation arc of the accelerator with different target gases, e.g., hydrogen, deuterium, helium, oxygen, argon, or xenon. Detailed studies have been carried out at the existing A1 multi-spect… ▽ More A cryogenic supersonic gas jet target was developed for the MAGIX experiment at the high-intensity electron accelerator MESA. It will be operated as an internal, windowless target in the energy-recovering recirculation arc of the accelerator with different target gases, e.g., hydrogen, deuterium, helium, oxygen, argon, or xenon. Detailed studies have been carried out at the existing A1 multi-spectrometer facility at the electron accelerator MAMI. This paper focuses on the developed handling procedures and diagnostic tools, and on the performance of the gas jet target under beam conditions. Considering the special features of this type of target, it proves to be well suited for a new generation of high-precision electron scattering experiments at high-intensity electron accelerators. △ Less

Submitted 16 July, 2021; v1 submitted 27 April, 2021; originally announced April 2021.

Science Requirements and Detector Concepts for the Electron-Ion Collider: EIC Yellow Report

Authors: R. Abdul Khalek, A. Accardi, J. Adam, D. Adamiak, W. Akers, M. Albaladejo, A. Al-bataineh, M. G. Alexeev, F. Ameli, P. Antonioli, N. Armesto, W. R. Armstrong, M. Arratia, J. Arrington, A. Asaturyan, M. Asai, E. C. Aschenauer, S. Aune, H. Avagyan, C. Ayerbe Gayoso, B. Azmoun, A. Bacchetta, M. D. Baker, F. Barbosa, L. Barion , et al. (390 additional authors not shown)

Abstract: This report describes the physics case, the resulting detector requirements, and the evolving detector concepts for the experimental program at the Electron-Ion Collider (EIC). The EIC will be a powerful new high-luminosity facility in the United States with the capability to collide high-energy electron beams with high-energy proton and ion beams, providing access to those regions in the nucleon… ▽ More This report describes the physics case, the resulting detector requirements, and the evolving detector concepts for the experimental program at the Electron-Ion Collider (EIC). The EIC will be a powerful new high-luminosity facility in the United States with the capability to collide high-energy electron beams with high-energy proton and ion beams, providing access to those regions in the nucleon and nuclei where their structure is dominated by gluons. Moreover, polarized beams in the EIC will give unprecedented access to the spatial and spin structure of the proton, neutron, and light ions. The studies leading to this document were commissioned and organized by the EIC User Group with the objective of advancing the state and detail of the physics program and developing detector concepts that meet the emerging requirements in preparation for the realization of the EIC. The effort aims to provide the basis for further development of concepts for experimental equipment best suited for the science needs, including the importance of two complementary detectors and interaction regions. This report consists of three volumes. Volume I is an executive summary of our findings and developed concepts. In Volume II we describe studies of a wide range of physics measurements and the emerging requirements on detector acceptance and performance. Volume III discusses general-purpose detector concepts and the underlying technologies to meet the physics requirements. These considerations will form the basis for a world-class experimental program that aims to increase our understanding of the fundamental structure of all visible matter △ Less

Submitted 26 October, 2021; v1 submitted 8 March, 2021; originally announced March 2021.

Comments: 902 pages, 415 authors, 151 institutions

Report number: BNL-220990-2021-FORE, JLAB-PHY-21-3198, LA-UR-21-20953

Journal ref: Nucl. Phys. A 1026 (2022) 122447

Pauli blocking of atomic spontaneous decay

Authors: Christian Sanner, Lindsay Sonderhouse, Ross B. Hutson, Lingfeng Yan, William R. Milner, Jun Ye

Abstract: Spontaneous decay of an excited atomic state is a fundamental process that originates from the interaction between matter and vacuum modes of the electromagnetic field. The rate of decay can thus be engineered by modifying the density of final states of the joint atom-photon system. Imposing suitable boundary conditions on the electromagnetic field has been shown to alter the density of vacuum mod… ▽ More Spontaneous decay of an excited atomic state is a fundamental process that originates from the interaction between matter and vacuum modes of the electromagnetic field. The rate of decay can thus be engineered by modifying the density of final states of the joint atom-photon system. Imposing suitable boundary conditions on the electromagnetic field has been shown to alter the density of vacuum modes near the atomic transition, resulting in modified atomic decay rates. Here we report the first experimental demonstration of suppression of atomic radiative decay by reducing the density of available energy-momentum modes of the atomic motion when it is embedded inside a Fermi sea. △ Less

Submitted 3 March, 2021; originally announced March 2021.

Thermal noise and mechanical loss of SiO$_2$/Ta$_2$O$_5$ optical coatings at cryogenic temperatures

Authors: John M Robinson, Eric Oelker, William R Milner, Dhruv Kedar, Wei Zhang, Thomas Legero, Dan G Matei, Sebastian Hafner, Fritz Riehle, Uwe Sterr, Jun Ye

Abstract: Mechanical loss of dielectric mirror coatings sets fundamental limits for both gravitational wave detectors and cavity-stabilized optical local oscillators for atomic clocks. Two approaches are used to determine the mechanical loss: ringdown measurements of the coating quality factor and direct measurement of the coating thermal noise. Here we report a systematic study of the mirror thermal noise… ▽ More Mechanical loss of dielectric mirror coatings sets fundamental limits for both gravitational wave detectors and cavity-stabilized optical local oscillators for atomic clocks. Two approaches are used to determine the mechanical loss: ringdown measurements of the coating quality factor and direct measurement of the coating thermal noise. Here we report a systematic study of the mirror thermal noise from room temperature to 4 K by operating reference cavities at these temperatures. The directly measured thermal noise is used to extract the corresponding mechanical loss for SiO$_2$/Ta$_2$O$_5$ coatings, which are compared with previously reported values. △ Less

Submitted 10 November, 2020; originally announced November 2020.

Precision Metrology Meets Cosmology: Improved Constraints on Ultralight Dark Matter from Atom-Cavity Frequency Comparisons

Authors: Colin J. Kennedy, Eric Oelker, John M. Robinson, Tobias Bothwell, Dhruv Kedar, William R. Milner, G. Edward Marti, Andrei Derevianko, Jun Ye

Abstract: We conduct frequency comparisons between a state-of-the-art strontium optical lattice clock, a cryogenic crystalline silicon cavity, and a hydrogen maser to set new bounds on the coupling of ultralight dark matter to Standard Model particles and fields in the mass range of $10^{-16}$ $-$ $10^{-21}$ eV. The key advantage of this two-part ratio comparison is the differential sensitivities to time va… ▽ More We conduct frequency comparisons between a state-of-the-art strontium optical lattice clock, a cryogenic crystalline silicon cavity, and a hydrogen maser to set new bounds on the coupling of ultralight dark matter to Standard Model particles and fields in the mass range of $10^{-16}$ $-$ $10^{-21}$ eV. The key advantage of this two-part ratio comparison is the differential sensitivities to time variation of both the fine-structure constant and the electron mass, achieving a substantially improved limit on the moduli of ultralight dark matter, particularly at higher masses than typical atomic spectroscopic results. Furthermore, we demonstrate an extension of the search range to even higher masses by use of dynamical decoupling techniques. These results highlight the importance of using the best performing atomic clocks for fundamental physics applications as all-optical timescales are increasingly integrated with, and will eventually supplant, existing microwave timescales. △ Less

Submitted 20 August, 2020; originally announced August 2020.

Comments: 11 pages, 10 figures

Journal ref: Phys. Rev. Lett. 125, 201302 (2020)

Optical Atomic Clock Comparison through Turbulent Air

Authors: Martha I. Bodine, Jean-Daniel Deschênes, Isaac H. Khader, William C. Swann, Holly Leopardi, Kyle Beloy, Tobias Bothwell, Samuel M. Brewer, Sarah L. Bromley, Jwo-Sy Chen, Scott A. Diddams, Robert J. Fasano, Tara M. Fortier, Youssef S. Hassan, David B. Hume, Dhruv Kedar, Colin J. Kennedy, Amanda Koepke, David R. Leibrandt, Andrew D. Ludlow, William F. McGrew, William R. Milner, Daniele Nicolodi, Eric Oelker, Thomas E. Parker , et al. (10 additional authors not shown)

Abstract: We use frequency comb-based optical two-way time-frequency transfer (O-TWTFT) to measure the optical frequency ratio of state-of-the-art ytterbium and strontium optical atomic clocks separated by a 1.5 km open-air link. Our free-space measurement is compared to a simultaneous measurement acquired via a noise-cancelled fiber link. Despite non-stationary, ps-level time-of-flight variations in the fr… ▽ More We use frequency comb-based optical two-way time-frequency transfer (O-TWTFT) to measure the optical frequency ratio of state-of-the-art ytterbium and strontium optical atomic clocks separated by a 1.5 km open-air link. Our free-space measurement is compared to a simultaneous measurement acquired via a noise-cancelled fiber link. Despite non-stationary, ps-level time-of-flight variations in the free-space link, ratio measurements obtained from the two links, averaged over 30.5 hours across six days, agree to $6\times10^{-19}$, showing that O-TWTFT can support free-space atomic clock comparisons below the $10^{-18}$ level. △ Less

Submitted 11 September, 2020; v1 submitted 1 June, 2020; originally announced June 2020.

Journal ref: Phys. Rev. Research 2, 033395 (2020)

Frequency Ratio Measurements with 18-digit Accuracy Using a Network of Optical Clocks

Authors: Boulder Atomic Clock Optical Network, Collaboration, :, Kyle Beloy, Martha I. Bodine, Tobias Bothwell, Samuel M. Brewer, Sarah L. Bromley, Jwo-Sy Chen, Jean-Daniel Deschênes, Scott A. Diddams, Robert J. Fasano, Tara M. Fortier, Youssef S. Hassan, David B. Hume, Dhruv Kedar, Colin J. Kennedy, Isaac Khader, Amanda Koepke, David R. Leibrandt, Holly Leopardi, Andrew D. Ludlow, William F. McGrew, William R. Milner, Nathan R. Newbury , et al. (13 additional authors not shown)

Abstract: Atomic clocks occupy a unique position in measurement science, exhibiting higher accuracy than any other measurement standard and underpinning six out of seven base units in the SI system. By exploiting higher resonance frequencies, optical atomic clocks now achieve greater stability and lower frequency uncertainty than existing primary standards. Here, we report frequency ratios of the $^{27}$Al… ▽ More Atomic clocks occupy a unique position in measurement science, exhibiting higher accuracy than any other measurement standard and underpinning six out of seven base units in the SI system. By exploiting higher resonance frequencies, optical atomic clocks now achieve greater stability and lower frequency uncertainty than existing primary standards. Here, we report frequency ratios of the $^{27}$Al$^+$, $^{171}$Yb and $^{87}$Sr optical clocks in Boulder, Colorado, measured across an optical network spanned by both fiber and free-space links. These ratios have been evaluated with measurement uncertainties between $6\times10^{-18}$ and $8\times10^{-18}$, making them the most accurate reported measurements of frequency ratios to date. This represents a critical step towards redefinition of the SI second and future applications such as relativistic geodesy and tests of fundamental physics. △ Less

Submitted 29 May, 2020; originally announced May 2020.

Comments: 51 pages, 12 figures, 6 tables

A tweezer clock with half-minute atomic coherence at optical frequencies and high relative stability

Authors: Aaron W. Young, William J. Eckner, William R. Milner, Dhruv Kedar, Matthew A. Norcia, Eric Oelker, Nathan Schine, Jun Ye, Adam M. Kaufman

Abstract: The preparation of large, low-entropy, highly coherent ensembles of identical quantum systems is foundational for many studies in quantum metrology, simulation, and information. Here, we realize these features by leveraging the favorable properties of tweezer-trapped alkaline-earth atoms while introducing a new, hybrid approach to tailoring optical potentials that balances scalability, high-fideli… ▽ More The preparation of large, low-entropy, highly coherent ensembles of identical quantum systems is foundational for many studies in quantum metrology, simulation, and information. Here, we realize these features by leveraging the favorable properties of tweezer-trapped alkaline-earth atoms while introducing a new, hybrid approach to tailoring optical potentials that balances scalability, high-fidelity state preparation, site-resolved readout, and preservation of atomic coherence. With this approach, we achieve trapping and optical clock excited-state lifetimes exceeding $ 40 $ seconds in ensembles of approximately $ 150 $ atoms. This leads to half-minute-scale atomic coherence on an optical clock transition, corresponding to quality factors well in excess of $10^{16}$. These coherence times and atom numbers reduce the effect of quantum projection noise to a level that is on par with leading atomic systems, yielding a relative fractional frequency stability of $5.2(3)\times10^{-17}~(τ/s)^{-1/2}$ for synchronous clock comparisons between sub-ensembles within the tweezer array. When further combined with the microscopic control and readout available in this system, these results pave the way towards long-lived engineered entanglement on an optical clock transition in tailored atom arrays. △ Less

Submitted 23 June, 2020; v1 submitted 13 April, 2020; originally announced April 2020.

Comments: 11 pages, 5 figures (main text); 17 pages, 7 figures (supplemental materials)

Journal ref: Nature 588, 408-413 (2020)

Thermodynamics of a deeply degenerate SU($N$)-symmetric Fermi gas

Authors: Lindsay Sonderhouse, Christian Sanner, Ross B. Hutson, Akihisa Goban, Thomas Bilitewski, Lingfeng Yan, William R. Milner, Ana Maria Rey, Jun Ye

Abstract: Many-body quantum systems can exhibit a striking degree of symmetry unparalleled by their classical counterparts. While in real materials SU($N$) symmetry is an idealization, this symmetry is pristinely realized in fully controllable ultracold alkaline-earth atomic gases. Here, we study an SU($N$)-symmetric Fermi liquid of $^{87}$Sr atoms, where $N$ can be tuned to be as large as 10. In the deeply… ▽ More Many-body quantum systems can exhibit a striking degree of symmetry unparalleled by their classical counterparts. While in real materials SU($N$) symmetry is an idealization, this symmetry is pristinely realized in fully controllable ultracold alkaline-earth atomic gases. Here, we study an SU($N$)-symmetric Fermi liquid of $^{87}$Sr atoms, where $N$ can be tuned to be as large as 10. In the deeply degenerate regime, we show through precise measurements of density fluctuations and expansion dynamics that the large $N$ of spin states under SU($N$) symmetry leads to pronounced interaction effects in a system with a nominally negligible interaction parameter. Accounting for these effects we demonstrate thermometry accurate to one-hundredth of the Fermi energy. We also demonstrate record speed for preparing degenerate Fermi seas, reaching $T/T_F = 0.12$ in under 3 s, enabled by the SU($N$) symmetric interactions. This, along with the introduction of a new spin polarizing method, enables operation of a 3D optical lattice clock in the band insulating-regime. △ Less

Submitted 7 March, 2020; v1 submitted 4 March, 2020; originally announced March 2020.

Comments: 10 pages, 5 figures

Conceptual Design of a Polarized 3He Target for the CLAS12 Spectrometer

Authors: James Maxwell, Richard Milner

Abstract: We present a conceptual design for a polarized $^3$He target for Jefferson Lab's CLAS12 spectrometer in its standard configuration. This two-cell target will take advantage of advancements in optical pumping techniques at high magnetic field to create 60\% longitudinally polarized $^3$He gas in a pumping cell inside the CLAS12 5 T solenoid. By transferring this gas to a 20 cm long, 5 K target cell… ▽ More We present a conceptual design for a polarized $^3$He target for Jefferson Lab's CLAS12 spectrometer in its standard configuration. This two-cell target will take advantage of advancements in optical pumping techniques at high magnetic field to create 60\% longitudinally polarized $^3$He gas in a pumping cell inside the CLAS12 5 T solenoid. By transferring this gas to a 20 cm long, 5 K target cell, a target thickness of $3 \times 10^{21}$ $^3$He/cm$^2$ will be produced, reaching the detector's specified maximum luminosity with a beam current of 2.5 $μA$. △ Less

Submitted 15 November, 2019; originally announced November 2019.

A New Cryogenic Apparatus to Search for the Neutron Electric Dipole Moment

Authors: M. W. Ahmed, R. Alarcon, A. Aleksandrova, S. Baessler, L. Barron-Palos, L. M. Bartoszek, D. H. Beck, M. Behzadipour, I. Berkutov, J. Bessuille, M. Blatnik, M. Broering, L. J. Broussard, M. Busch, R. Carr, V. Cianciolo, S. M. Clayton, M. D. Cooper, C. Crawford, S. A. Currie, C. Daurer, R. Dipert, K. Dow, D. Dutta, Y. Efremenko , et al. (69 additional authors not shown)

Abstract: A cryogenic apparatus is described that enables a new experiment, nEDM@SNS, with a major improvement in sensitivity compared to the existing limit in the search for a neutron Electric Dipole Moment (EDM). It uses superfluid $^4$He to produce a high density of Ultra-Cold Neutrons (UCN) which are contained in a suitably coated pair of measurement cells. The experiment, to be operated at the Spallati… ▽ More A cryogenic apparatus is described that enables a new experiment, nEDM@SNS, with a major improvement in sensitivity compared to the existing limit in the search for a neutron Electric Dipole Moment (EDM). It uses superfluid $^4$He to produce a high density of Ultra-Cold Neutrons (UCN) which are contained in a suitably coated pair of measurement cells. The experiment, to be operated at the Spallation Neutron Source at Oak Ridge National Laboratory, uses polarized $^3$He from an Atomic Beam Source injected into the superfluid $^4$He and transported to the measurement cells as a co-magnetometer. The superfluid $^4$He is also used as an insulating medium allowing significantly higher electric fields, compared to previous experiments, to be maintained across the measurement cells. These features provide an ultimate statistical uncertainty for the EDM of $2-3\times 10^{-28}$ e-cm, with anticipated systematic uncertainties below this level. △ Less

Submitted 20 November, 2019; v1 submitted 26 August, 2019; originally announced August 2019.

Journal ref: Journal of Instrumentation, Vol 14, P11017, 2019

Demonstration of a time scale based on a stable optical carrier

Authors: William R. Milner, John M. Robinson, Colin J. Kennedy, Tobias Bothwell, Dhruv Kedar, Dan G. Matei, Thomas Legero, Uwe Sterr, Fritz Riehle, Holly Leopardi, Tara M. Fortier, Jeffrey A. Sherman, Judah Levine, Jian Yao, Jun Ye, Eric Oelker

Abstract: We demonstrate a time scale based on a phase stable optical carrier that accumulates an estimated time error of $48\pm94$ ps over 34 days of operation. This all-optical time scale is formed with a cryogenic silicon cavity exhibiting improved long-term stability and an accurate $^{87}$Sr lattice clock. We show that this new time scale architecture outperforms existing microwave time scales, even wh… ▽ More We demonstrate a time scale based on a phase stable optical carrier that accumulates an estimated time error of $48\pm94$ ps over 34 days of operation. This all-optical time scale is formed with a cryogenic silicon cavity exhibiting improved long-term stability and an accurate $^{87}$Sr lattice clock. We show that this new time scale architecture outperforms existing microwave time scales, even when they are steered to optical frequency standards. Our analysis indicates that this time scale is capable of reaching a stability below $1\times10^{-17}$ after a few months of averaging, making timekeeping at the $10^{-18}$ level a realistic prospect. △ Less

Submitted 6 July, 2019; originally announced July 2019.

Comments: 13 pages, 12 Figures

Journal ref: Phys. Rev. Lett. 123, 173201 (2019)

Measurement of Moller Scattering at 2.5 MeV

Authors: C. S. Epstein, R. Johnston, S. Lee, J. C. Bernauer, R. Corliss, K. Dow, P. Fisher, I. Friscic, D. Hasell, R. G. Milner, P. Moran, S. G. Steadman, Y. Wang, J. Dodge, E. Ihloff, J. Kelsey, C. Vidal, C. M. Cooke

Abstract: Moller scattering is one of the most fundamental processes in QED. Understanding it to high precision is necessary for a variety of modern nuclear and particle physics experiments. In a recent calculation, existing soft-photon radiative corrections were combined with new hard-photon bremsstrahlung calculations to take into account the effect of photon emission at any photon energy, where the elect… ▽ More Moller scattering is one of the most fundamental processes in QED. Understanding it to high precision is necessary for a variety of modern nuclear and particle physics experiments. In a recent calculation, existing soft-photon radiative corrections were combined with new hard-photon bremsstrahlung calculations to take into account the effect of photon emission at any photon energy, where the electron mass was included at all steps. To test the calculation, an experiment was carried out using the 3 MV Van de Graaff electrostatic accelerator at the MIT High Voltage Research Laboratory. Momentum spectra at three scattering angles at an incident electron energy of 2.5 MeV are reported here, and compared to the simulated radiative Moller spectra, based on our previous calculation. Good agreement between the measurements and our calculation is observed in the momentum spectrum at the three angles. △ Less

Submitted 13 April, 2019; v1 submitted 21 March, 2019; originally announced March 2019.

Journal ref: Phys. Rev. D 102, 012006 (2020)

The neutron electric dipole moment experiment at the Spallation Neutron Source

Authors: K. K. H. Leung, M. Ahmed, R. Alarcon, A. Aleksandrova, S. Baeßler, L. Barrón-Palos, L. Bartoszek, D. H. Beck, M. Behzadipour, J. Bessuille, M. A. Blatnik, M. Broering, L. J. Broussard, M. Busch, R. Carr, P. -H. Chu, V. Cianciolo, S. M. Clayton, M. D. Cooper, C. Crawford, S. A. Currie, C. Daurer, R. Dipert, K. Dow, D. Dutta , et al. (68 additional authors not shown)

Abstract: Novel experimental techniques are required to make the next big leap in neutron electric dipole moment experimental sensitivity, both in terms of statistics and systematic error control. The nEDM experiment at the Spallation Neutron Source (nEDM@SNS) will implement the scheme of Golub & Lamoreaux [Phys. Rep., 237, 1 (1994)]. The unique properties of combining polarized ultracold neutrons, polarize… ▽ More Novel experimental techniques are required to make the next big leap in neutron electric dipole moment experimental sensitivity, both in terms of statistics and systematic error control. The nEDM experiment at the Spallation Neutron Source (nEDM@SNS) will implement the scheme of Golub & Lamoreaux [Phys. Rep., 237, 1 (1994)]. The unique properties of combining polarized ultracold neutrons, polarized $^3$He, and superfluid $^4$He will be exploited to provide a sensitivity to $\sim 10^{-28}\,e{\rm \,\cdot\, cm}$. Our cryogenic apparatus will deploy two small ($3\,{\rm L}$) measurement cells with a high density of ultracold neutrons produced and spin analyzed in situ. The electric field strength, precession time, magnetic shielding, and detected UCN number will all be enhanced compared to previous room temperature Ramsey measurements. Our $^3$He co-magnetometer offers unique control of systematic effects, in particular the Bloch-Siegert induced false EDM. Furthermore, there will be two distinct measurement modes: free precession and dressed spin. This will provide an important self-check of our results. Following five years of "critical component demonstration," our collaboration transitioned to a "large scale integration" phase in 2018. An overview of our measurement techniques, experimental design, and brief updates are described in these proceedings. △ Less

Submitted 4 October, 2019; v1 submitted 6 March, 2019; originally announced March 2019.

Comments: Submitted to proceedings of PPNS 2018 - International Workshop on Particle physics at Neutron Sources (https://www.webofconferences.org/epj-web-of-conferences-forthcoming-conferences/1148-ppns-2018)

Design and Operation of a Windowless Gas Target Internal to a Solenoidal Magnet for Use with a Megawatt Electron Beam

Authors: S. Lee, R. Corliss, I. Friščić, R. Alarcon, S. Aulenbacher, J. Balewski, S. Benson, J. C. Bernauer, J. Bessuille, J. Boyce, J. Coleman, D. Douglas, C. S. Epstein, P. Fisher, S. Frierson, M. Garçon, J. Grames, D. Hasell, C. Hernandez-Garcia, E. Ihloff, R. Johnston, K. Jordan, R. Kazimi, J. Kelsey, M. Kohl , et al. (15 additional authors not shown)

Abstract: A windowless hydrogen gas target of nominal thickness $10^{19}$ cm$^{-2}$ is an essential component of the DarkLight experiment, which is designed to utilize the megawatt electron beam at an Energy Recovery Linac (ERL). The design of such a target is challenging because the pressure drops by many orders of magnitude between the central, high-density section of the target and the surrounding beamli… ▽ More A windowless hydrogen gas target of nominal thickness $10^{19}$ cm$^{-2}$ is an essential component of the DarkLight experiment, which is designed to utilize the megawatt electron beam at an Energy Recovery Linac (ERL). The design of such a target is challenging because the pressure drops by many orders of magnitude between the central, high-density section of the target and the surrounding beamline, resulting in laminar, transitional, and finally molecular flow regimes. The target system was assembled and operated at Jefferson Lab's Low Energy Recirculator Facility (LERF) in 2016, and subsequently underwent several revisions and calibration tests at MIT Bates in 2017. The system at dynamic equilibrium was simulated in COMSOL to provide a better understanding of its optimal operation at other working points. We have determined that a windowless gas target with sufficiently high density for DarkLight's experimental needs is feasible in an ERL environment. △ Less

Submitted 30 May, 2019; v1 submitted 6 March, 2019; originally announced March 2019.

Comments: 11 pages, 14 figures; v2: minor improvements; v3: author list updated; v4: minor revision

Journal ref: Nucl. Instrum. Methods Phys. Res. A, 939 (2019), pp. 46-54

Enhanced Polarization of Low Pressure $^3$He through Metastability-Exchange Optical Pumping at High Field

Authors: J. D. Maxwell, J. Alessi, G. Atoian, E. Beebe, C. S. Epstein, R. G. Milner, M. Musgrave, A. Pikin, J. Ritter, A. Zelenski

Abstract: We report high steady-state nuclear polarization of 1 torr $^3$He gas nuclei via metastability-exchange optical pumping at magnetic fields above 2 T. The introduction of highly polarized $^3$He gas into Brookhaven's Electron Beam Ion Source would enable a new, polarized $^3$He ion source for use at the Relativistic Heavy Ion Collider and a future Electron-Ion Collider facility. By adapting recent… ▽ More We report high steady-state nuclear polarization of 1 torr $^3$He gas nuclei via metastability-exchange optical pumping at magnetic fields above 2 T. The introduction of highly polarized $^3$He gas into Brookhaven's Electron Beam Ion Source would enable a new, polarized $^3$He ion source for use at the Relativistic Heavy Ion Collider and a future Electron-Ion Collider facility. By adapting recent developments in high field metastability-exchange optical pumping for higher pressure gas, we have successfully polarized 1 torr $^3$He sealed cells in the EBIS solenoid. Through careful manipulation of the RF discharge parameters, polarizations above 80% were attained at 2, 3 and 4 T, with 89% being reached at 3 T with a 664 s relaxation time. △ Less

Submitted 11 April, 2019; v1 submitted 14 December, 2018; originally announced December 2018.

Crystalline optical cavity at 4 K with thermal noise limited instability and ultralow drift

Authors: John M. Robinson, Eric Oelker, William R. Milner, Wei Zhang, Thomas Legero, Dan G. Matei, Fritz Riehle, Uwe Sterr, Jun Ye

Abstract: Crystalline optical cavities are the foundation of today's state-of-the-art ultrastable lasers. Building on our previous silicon cavity effort, we now achieve the fundamental thermal noise-limited stability for a 6 cm long silicon cavity cooled to 4 Kelvin, reaching $6.5\times10^{-17}$ from 0.8 to 80 seconds. We also report for the first time a clear linear dependence of the cavity frequency drift… ▽ More Crystalline optical cavities are the foundation of today's state-of-the-art ultrastable lasers. Building on our previous silicon cavity effort, we now achieve the fundamental thermal noise-limited stability for a 6 cm long silicon cavity cooled to 4 Kelvin, reaching $6.5\times10^{-17}$ from 0.8 to 80 seconds. We also report for the first time a clear linear dependence of the cavity frequency drift on the incident optical power. The lowest fractional frequency drift of $-3\times10^{-19}$/s is attained at a transmitted power of 40 nW, with an extrapolated drift approaching zero in the absence of optical power. These demonstrations provide a promising direction to reach a new performance domain for stable lasers, with stability better than $1\times10^{-17}$ and fractional linear drift below $1\times10^{-19}$/s. △ Less

Submitted 6 December, 2018; originally announced December 2018.

A helical-shape scintillating fiber trigger and tracker system for the DarkLight experiment and beyond

Authors: Yimin Wang, Ross Corliss, Richard G. Milner, Christoph Tschalaer, Jan C. Bernauer

Abstract: The search for new physics beyond the Standard Model has interesting possibilities at low energies. For example, the recent 6.8$σ$ anomaly reported in the invariant mass of $e^+e^-$ pairs from $^8\text{Be}$ nuclear transitions and the discrepancy between predicted and measured values of muon g-2 give strong motivations for a protophobic fifth-force model. At low energies, the electromagnetic inter… ▽ More The search for new physics beyond the Standard Model has interesting possibilities at low energies. For example, the recent 6.8$σ$ anomaly reported in the invariant mass of $e^+e^-$ pairs from $^8\text{Be}$ nuclear transitions and the discrepancy between predicted and measured values of muon g-2 give strong motivations for a protophobic fifth-force model. At low energies, the electromagnetic interaction is well understood and produces straightforward final states, making it an excellent probe of such models. However, to achieve the required precision, an experiment must address the substantially higher rate of electromagnetic backgrounds. In this paper, we present the results of simulation studies of a trigger system, motivated by the DarkLight experiment, using helical-shape scintillating fibers in a solenoidal magnetic field to veto electron-proton elastic scattering and the associated radiative processes. We also assess the performance of a tracking detector for lepton final states using scintillating fibers in the same setup. △ Less

Submitted 25 March, 2019; v1 submitted 4 December, 2018; originally announced December 2018.

Realization of a Large-Acceptance Faraday Cup for 3 MeV Electrons

Authors: R. Johnston, J. Bernauer, C. M. Cooke, R. Corliss, C. S. Epstein, P. Fisher, I. Friščić, D. Hasell, E. Ihloff, J. Kelsey, S. Lee, R. G. Milner, P. Moran, S. G. Steadman, C. Vidal

Abstract: The design, construction, installation, and testing of a Faraday Cup intended to measure the current of a 3 MeV, 1 microampere electron beam is described. Built as a current monitor for a Møller scattering measurement at the MIT High Voltage Research Laboratory, the device combines a large angular acceptance with the capability to measure a continuous, low energy beam. Bench studies of its perform… ▽ More The design, construction, installation, and testing of a Faraday Cup intended to measure the current of a 3 MeV, 1 microampere electron beam is described. Built as a current monitor for a Møller scattering measurement at the MIT High Voltage Research Laboratory, the device combines a large angular acceptance with the capability to measure a continuous, low energy beam. Bench studies of its performance demonstrate current measurements accurate to the percent level at 1 microampere. The Faraday Cup was designed and constructed at MIT and has been in use at the HVRL since 2017, providing a significantly more detailed measurement of beam current than was previously available. △ Less

Submitted 27 November, 2018; originally announced November 2018.

Comments: 4 pages

A novel technique for determining luminosity in electron-scattering/positron-scattering experiments from multi-interaction events

Authors: A. Schmidt, C. O'Connor, J. C. Bernauer, R. Milner

Abstract: The OLYMPUS experiment measured the cross-section ratio of positron-proton elastic scattering relative to electron-proton elastic scattering to look for evidence of hard two-photon exchange. To make this measurement, the experiment alternated between electron beam and positron beam running modes, with the relative integrated luminosities of the two running modes providing the crucial normalization… ▽ More The OLYMPUS experiment measured the cross-section ratio of positron-proton elastic scattering relative to electron-proton elastic scattering to look for evidence of hard two-photon exchange. To make this measurement, the experiment alternated between electron beam and positron beam running modes, with the relative integrated luminosities of the two running modes providing the crucial normalization. For this reason, OLYMPUS had several redundant luminosity monitoring systems, including a pair of electromagnetic calorimeters positioned downstream from the target to detect symmetric Mø ller and Bhabha scattering from atomic electrons in the hydrogen gas target. Though this system was designed to monitor the rate of events with single Mø ller/Bhabha interactions, we found that a more accurate determination of relative luminosity could be made by additionally considering the rate of events with both a Mø ller/Bhabha interaction and a concurrent elastic $ep$ interaction. This method was improved by small corrections for the variance of the current within bunches in the storage ring and for the probability of three interactions occurring within a bunch. After accounting for systematic effects, we estimate that the method is accurate in determining the relative luminosity to within 0.36\%. This precise technique can be employed in future electron-proton and positron-proton scattering experiments to monitor relative luminosity between different running modes. △ Less

Submitted 22 September, 2017; v1 submitted 14 August, 2017; originally announced August 2017.

Journal ref: NIM A 877 pp. 112--117 (2018)

International Spin Physics 2014 Summary

Authors: Richard G. Milner

Abstract: The Stern-Gerlach experiment and the origin of electron spin are described in historical context. SPIN 2014 occurs on the fortieth anniversary of the first International High Energy Spin Physics Symposium at Argonne in 1974. A brief history of the international spin conference series is presented. The Stern-Gerlach experiment and the origin of electron spin are described in historical context. SPIN 2014 occurs on the fortieth anniversary of the first International High Energy Spin Physics Symposium at Argonne in 1974. A brief history of the international spin conference series is presented. △ Less

Submitted 6 February, 2015; originally announced February 2015.

Comments: To be published by World Scientific in the International Journal of Modern Physics: Conference Series

Diffusive Transfer of Polarized 3He Gas through Depolarizing Magnetic Gradients

Authors: James D. Maxwell, Charles S. Epstein, Richard G. Milner

Abstract: Transfer of polarized 3He gas across spatially varying magnetic fields will facilitate a new source of polarized 3He ions for particle accelerators. In this context, depolarization of atoms as they pass through regions of significant transverse field gradients is a major concern. To understand these depolarization effects, we have built a system consisting of a Helmholtz coil pair and a solenoid,… ▽ More Transfer of polarized 3He gas across spatially varying magnetic fields will facilitate a new source of polarized 3He ions for particle accelerators. In this context, depolarization of atoms as they pass through regions of significant transverse field gradients is a major concern. To understand these depolarization effects, we have built a system consisting of a Helmholtz coil pair and a solenoid, both with central magnetic fields of order 30 gauss. The atoms are polarized via metastability exchange optical pumping in the Helmholtz coil and are in diffusive contact via a glass tube with a second test cell in the solenoid. We have carried out measurements of the spin relaxation during transfer of polarization in 3He at 1 torr by diffusion. We explore the use of measurements of the loss of polarization taken in one cell to infer the polarization in the other cell. △ Less

Submitted 18 December, 2014; originally announced December 2014.

The DarkLight Experiment: A Precision Search for New Physics at Low Energies

Authors: J. Balewski, J. Bernauer, J. Bessuille, R. Corliss, R. Cowan, C. Epstein, P. Fisher, D. Hasell, E. Ihloff, Y. Kahn, J. Kelsey, R. Milner, S. Steadman, J. Thaler, C. Tschalaer, C. Vidal, S. Benson, J. Boyce, D. Douglas, P. Evtushenko, C. Hernandez-Garcia, C. Keith, C. Tennant, S. Zhang, R. Alarcon , et al. (15 additional authors not shown)

Abstract: We describe the current status of the DarkLight experiment at Jefferson Laboratory. DarkLight is motivated by the possibility that a dark photon in the mass range 10 to 100 MeV/c$^2$ could couple the dark sector to the Standard Model. DarkLight will precisely measure electron proton scattering using the 100 MeV electron beam of intensity 5 mA at the Jefferson Laboratory energy recovering linac inc… ▽ More We describe the current status of the DarkLight experiment at Jefferson Laboratory. DarkLight is motivated by the possibility that a dark photon in the mass range 10 to 100 MeV/c$^2$ could couple the dark sector to the Standard Model. DarkLight will precisely measure electron proton scattering using the 100 MeV electron beam of intensity 5 mA at the Jefferson Laboratory energy recovering linac incident on a windowless gas target of molecular hydrogen. The complete final state including scattered electron, recoil proton, and e+e- pair will be detected. A phase-I experiment has been funded and is expected to take data in the next eighteen months. The complete phase-II experiment is under final design and could run within two years after phase-I is completed. The DarkLight experiment drives development of new technology for beam, target, and detector and provides a new means to carry out electron scattering experiments at low momentum transfers. △ Less

Submitted 15 December, 2014; originally announced December 2014.

Comments: Whitepaper submitted to Town Meeting on Fundamental and Symmetries and Neutrinos, O'Hare airport, Chicago, IL

Liquid Crystal Polarimetry for Metastability Exchange Optical Pumping of 3He

Authors: James D. Maxwell, Charles S. Epstein, Richard G. Milner

Abstract: We detail the design and operation of a compact, discharge light polarimeter for metastability exchange optical pumping of 3He gas near 1 torr under a low magnetic field. The nuclear polarization of 3He can be discerned from its electron polarization, measured via the circular polarization of 668 nm discharge light from an RF excitation. This apparatus measures the circular polarization of this ve… ▽ More We detail the design and operation of a compact, discharge light polarimeter for metastability exchange optical pumping of 3He gas near 1 torr under a low magnetic field. The nuclear polarization of 3He can be discerned from its electron polarization, measured via the circular polarization of 668 nm discharge light from an RF excitation. This apparatus measures the circular polarization of this very dim discharge light using a nematic liquid crystal wave retarder (LCR) and a high-gain, transimpedance amplified Si photodiode. We outline corrections required in such a measurement, and discuss contributions to its systematic error. △ Less

Submitted 21 July, 2014; originally announced July 2014.