[en] The ESTU began operation in 1988 and achieved the design voltage of 20 MV in 1990. Since that time, improvements to the gas handling system, negative ion injector, accelerator terminal and control system have greatly increased its capability and reliability. Today, the ESTU can efficiently produce an extensive assortment of stable ions at wide-ranging energies in support of low-energy nuclear physics. (author)

[en] This study describes the design and performance of a 50 liter, two-segment ⁶Li-loaded liquid scintillator detector that was designed and operated as prototype for the PROSPECT (Precision Reactor Oscillation and Spectrum) Experiment. The two-segment detector was constructed according to the design specifications of the experiment. It features low-mass optical separators, an integrated source and optical calibration system, and materials that are compatible with the ⁶Li-doped scintillator developed by PROSPECT. We demonstrate a high light collection of 850±20 PE/MeV, an energy resolution of σ = 4.0±0.2% at 1 MeV, and efficient pulse-shape discrimination of low dE/dx (electronic recoil) and high dE/dx (nuclear recoil) energy depositions. An effective scintillation attenuation length of 85±3 cm is measured in each segment. The 0.1% by mass concentration of ⁶Li in the scintillator results in a measured neutron capture time of τ = 42.8±0.2 μs. The long-term stability of the scintillator is also discussed. Finally, the detector response meets the criteria necessary for achieving the PROSPECT physics goals and demonstrates features that may find application in fast neutron detection.

[en] The ESTU tandem at the Wright Nuclear Structure Laboratory at Yale University has a demonstrated capability of accelerating heavy ion beams with a terminal potential in excess of 21 MV. To exploit this resource properly, high mass resolution is required at the ion source and charge selection in the terminal. A new ion injector, including a compact 90deg magnet and high output sputter and charge exchange sources, has been assembled and tested. A new terminal, containing two foil strippers, a recirculating charge stripper and an off-axis electrostatic quadrupole charge separator has been designed, built and tested and awaits installation. Test results will be presented for these devices and the performance of the accelerator will be reviewed. (orig.)

[en] Current nuclear structure studies demand a wide range of heavy negative ion beams for tandem acceleration. Some of the wanted isotopes have low natural abundances and many have low or negative electron affinities. For these, gas injection or the use of hydrides, oxides, or fluorides is required to achieve usable intensities. The chemical properties of the target materials, and of the additive gases used to form molecular ions, often have detrimental effects on ion source performance and life. These effects include insulator breakdown, ionizer poisoning, and the erosion or deposition of material on critical electrodes. Methods of controlling sputter source conditions are being studied on the Wright Nuclear Structure Laboratory ion source test bench with the object of extending source life, increasing target efficiency, and achieving consistent negative ion outputs. Results are reported for several heavy ions including tellurium, neodymium, and ytterbium. copyright 1998 American Institute of Physics

[en] The Precision Reactor Oscillation and Spectrum (PROSPECT) Experiment is a reactor neutrino experiment designed to search for sterile neutrinos with a mass on the order of 1 eV/c² and to measure the spectrum of electron antineutrinos from a highly-enriched ²³⁵U nuclear reactor. The PROSPECT detector consists of an 11 by 14 array of optical segments in ⁶Li-loaded liquid scintillator at the High Flux Isotope Reactor in Oak Ridge National Laboratory. Antineutrino events are identified via inverse beta decay and read out by photomultiplier tubes located at the ends of each segment. The detector response is characterized using a radioactive source calibration system. This paper describes the design, operation, and performance of the PROSPECT source calibration system.

[en] We report results from a search for strangelets (small chunks of strange quark matter) in lunar soil using the Yale WNSL accelerator as a mass spectrometer. We have searched over a range in mass from A=42 to A=70 amu for nuclear charges 5, 6, 8, 9, and 11. No strangelets were found in the experiment. For strangelets with nuclear charge 8, a concentration in lunar soil higher than 10^-16 is excluded at the 95% confidence level. The implied limit on the strangelet flux in cosmic rays is the most sensitive to date for the covered range and is relevant to both recent theoretical flux predictions and a strangelet candidate event found by the AMS-01 experiment.

[en] A meter-long, 23-liter EJ-309 liquid scintillator detector has been constructed to study the light collection and pulse-shape discrimination performance of elongated scintillator cells for the PROSPECT reactor antineutrino experiment. The magnitude and uniformity of light collection and neutron-gamma discrimination power in the energy range of antineutrino inverse beta decay products have been studied using gamma and spontaneous fission calibration sources deployed along the cell axis. We also study neutron-gamma discrimination and light collection abilities for differing PMT and reflector configurations. Key design features for optimizing MeV-scale response and background rejection capabilities are identified

[en] This work reports the production and characterization of lithium-loaded liquid scintillator (LiLS) for the Precision Reactor Oscillation and Spectrum Experiment (PROSPECT) . Fifty-nine 90 liter batches of LiLS (⁶Li mass fraction 0.082%±0.001%) were produced and samples from all batches were characterized by measuring their optical absorbance relative to air, light yield relative to a pure liquid scintillator reference, and pulse shape discrimination capability. Fifty-seven batches passed the quality assurance criteria and were used for the PROSPECT experiment.

[en] PROSPECT, the Precision Reactor Oscillation and SPECTrum experiment, is a short-baseline reactor antineutrino experiment designed to provide precision measurements of the ²³⁵U product $\stackrel{¯<!--\; ??\; -->}{\mathrm{\nu <!--\; ??\; -->}}$_e spectrum, utilizing an optically segmented 4-ton liquid scintillator detector. PROSPECT's segmentation system, the optical grid, plays a central role in reconstructing the position and energy of $\stackrel{¯<!--\; ??\; -->}{\mathrm{\nu <!--\; ??\; -->}}$_e interactions in the detector. This paper is the technical reference for this PROSPECT subsystem, describing its design, fabrication, quality assurance, transportation and assembly in detail. In addition, the dimensional, optical and mechanical characterizations of optical grid components and the assembled PROSPECT target are also presented. The technical information and characterizations detailed here will inform geometry-related inputs for PROSPECT physics analysis, and can guide a variety of future particle detection development efforts, such as those using optically reflecting materials or filament-based 3D printing.

[en] The precision reactor oscillation and spectrum experiment, PROSPECT, is designed to make a precise measurement of the antineutrino spectrum from a highly-enriched uranium reactor and probe eV-scale sterile neutrinos by searching for neutrino oscillations over a distance of several meters. PROSPECT is conceived as a 2-phase experiment utilizing segmented ⁶Li-doped liquid scintillator detectors for both efficient detection of reactor antineutrinos through the inverse beta decay reaction and excellent background discrimination. PROSPECT Phase I consists of a movable 3 ton antineutrino detector at distances of 7–12 m from the reactor core. It will probe the best-fit point of the ${\mathrm{\nu <!--\; ??\; -->}}_e$ disappearance experiments at 4σ in 1 year and the favored region of the sterile neutrino parameter space at $><!--\; >\; -->3\mathrm{\sigma <!--\; ??\; -->}$ in 3 years. With a second antineutrino detector at 15–19 m from the reactor, Phase II of PROSPECT can probe the entire allowed parameter space below 10 eV² at 5σ in 3 additional years. The measurement of the reactor antineutrino spectrum and the search for short-baseline oscillations with PROSPECT will test the origin of the spectral deviations observed in recent ${\mathrm{\theta <!--\; ??\; -->}}_{13}$ experiments, search for sterile neutrinos, and conclusively address the hypothesis of sterile neutrinos as an explanation of the reactor anomaly. (topical review)