[en] A compact polarimeter has been constructed and calibrated to measure the polarization of 13-16 MeV protons, such as those emitted from the ³He(d,p)⁴He reaction near the E_d=430 keV resonance. The polarimeter uses p-⁴He elastic scattering as an analyzer. It consists of a ⁴He gas cell pressurized to 2.76 MPa and a left-right pair of CsI detectors collimated at 65 deg. to maximize the figure of merit for the device. The effective analyzing power and efficiency of the polarimeter have been measured as a function of energy using a collimated polarized proton beam. These measured values are in good agreement with a Monte Carlo computer simulation that forms the basis for the calibration curve for the device. Preliminary results from the ³He(d,p)⁴He reaction with polarized deuterons confirm that the proton polarimeter can be used to determine polarization transfer coefficients near the low-energy resonance

[en] Recent Wilkinson Microwave Anisotropy Probe (WMAP) measurements have determined the baryon density of the Universe Ω_b with a precision of about 4%. With Ω_b tightly constrained, comparisons of Big Bang nucleosynthesis (BBN) abundance predictions to primordial abundance observations can be made and used to test BBN models and/or to further constrain abundances of isotopes with weak observational limits. To push the limits and improve constraints on BBN models, uncertainties in key nuclear reaction rates must be minimized. To this end, we made new precise measurements of the ²H(d,p)³H and ²H(d,n)³He total cross sections at lab energies from 110 to 650 keV. A complete fit was performed in energy and angle to both angular distribution and normalization data for both reactions simultaneously. By including parameters for experimental variables in the fit, error correlations between detectors, reactions, and reaction energies were accurately tabulated by computational methods. With uncertainties around 2%±1% scale error, these new measurements significantly improve on the existing data set. At relevant temperatures, by using the data of the present work, both reaction rates are found to be about 7% higher than those in the widely used NACRE (nuclear astrophysics compilation of reaction rates) database. These data will thus lead not only to reduced uncertainties, but also to modifications in the BBN abundance predictions

[en] Individual Ba ions are trapped in a gas-filled linear ion trap and observed with a high signal-to-noise ratio by resonance fluorescence. Single-ion storage times of ∼5 min (∼1 min) are achieved using He (Ar) as a buffer gas at pressures in the range 8 x 10^-5 - 4 x 10^-3 torr. Trap dynamics in buffer gases are experimentally studied in the simple case of single ions. In particular, the cooling effects of light gases such as He and Ar and the destabilizing properties of heavier gases such as Xe are studied. A simple model is offered to explain the observed phenomenology

[en] Oxygen, nitrogen and methane purification efficiencies for a common zirconium getter are measured in 1050 Torr of xenon gas. Starting with impurity concentrations near 10^-6 g/g, the outlet impurity level is found to be less than 120 x10^-12 g/g for O₂ and less than 950x10^-12 g/g for N₂. For methane we find residual contamination of the purified gas at concentrations varying over three orders of magnitude, depending on the purifier temperature and the gas flow rate. A slight reduction in the purifier's methane efficiency is observed after 13 mg of this impurity has been absorbed, which we attribute to partial exhaustion of the purifier's capacity for this species. We also find that the purifier's ability to absorb N₂ and methane can be extinguished long before any decrease in O₂ performance is observed, and slower flow rates should be employed for xenon purification due to the cooling effect that the heavy gas has on the getter.

[en] We report on the development and performance of a high-sensitivity purity-analysis technique for gaseous xenon. The gas is sampled at macroscopic pressure from the system of interest using a UHV leak valve. The xenon present in the sample is removed with a liquid-nitrogen cold trap, and the remaining impurities are observed with a standard vacuum mass-spectroscopy device. Using calibrated samples of xenon gas spiked with known levels of impurities, we find that the minimum detectable levels of N₂, O₂, and methane are 1x10^-9, 160x10^-12, and 60 x10^-12 g/g, respectively. This represents an improvement of about a factor of 10 000 compared to measurements performed without a cold trap.

[en] We describe the design and operation of a system for xenon liquefaction in which the condenser is separated from the liquid storage vessel. The condenser is cooled by a pulse tube cryocooler, while the vessel is cooled only by the liquid xenon itself. This arrangement facilitates liquid particle detector research by allowing easy access to the upper and lower flanges of the vessel. We find that an external xenon gas pump is useful for increasing the rate at which cooling power is delivered to the vessel, and we present measurements of the power and efficiency of the apparatus.

[en] Angular distributions of σ(θ), A_y, iT₁₁, T₂₀, T₂₁, and T₂₂ have been measured for d-p scattering at E_c.m.=667 keV. This set of high-precision data is compared to variational calculations with the nucleon-nucleon potential alone and also to calculations including a three-nucleon (3N) potential. Agreement with cross section and tensor analyzing power data is excellent when a 3N potential is used. However, a comparison between the vector analyzing powers reveals differences of approximately 40% in the maxima of the angular distributions which is larger than reported at higher energies for both p-d and n-d scattering. The inclusion of phenomenological spin-orbit forces in a 3N potential improves the comparison with vector analyzing powers substantially. Single-energy phase-shift analyses were performed on this data set and a similar data set at E_c.m.=431.3 keV. The role of the different phase-shift parameters in fitting these data is discussed

[en] The polarization transfer coefficient K_y^y'(0 deg.) has been measured for the ³He(d,p)⁴He reaction at energies of 520, 890, and 1490 keV. The measured values are ≅-2/3, consistent with expectations based on the presence of a broad J^π=(3/2)⁺ resonance at E_d=430 keV. A comparison with data taken at somewhat higher energies reveals a large change in this observable as the reaction becomes dominated by direct neutron transfer

[en] New experimental results for the cross section and A_yy tensor analyzing power observables of the ³He(d,p)⁴He reaction at a scattering angle of θ=0 deg. are presented for E_d=0.52,0.89, and 1.49 MeV, and all linearly independent scattering amplitudes at this angle are calculated. A hybrid R-matrix+potential model is used to fit these results and other ³He(d,p)⁴He reaction data for E_d<1 MeV. This analysis indicates significant direct process contributions to the reaction mechanism

[en] The Center for Underground Physics (CUP) of the Institute for Basic Science (IBS) is searching for the neutrinoless double-beta decay ($0\mathrm{\nu <!--\; ??\; -->}\mathrm{\beta <!--\; ??\; -->}\mathrm{\beta <!--\; ??\; -->}$) of ${}^{100}$Mo in the molybdate crystals of the AMoRE experiment. The experiment requires pure scintillation crystals to minimize internal backgrounds that can affect the $0\mathrm{\nu <!--\; ??\; -->}\mathrm{\beta <!--\; ??\; -->}\mathrm{\beta <!--\; ??\; -->}$ signal. For the last few years, we have been growing and studying Li${}_2$MoO${}_4$ crystals in a clean-environment facility to minimize external contamination during the crystal growth. Before growing Li${}_2^{100}$MoO${}_4$ crystal, we have studied Li₂^natMoO${}_4$ crystal growth by a conventional Czochralski (CZ) grower. We grew a few different kinds of Li₂^natMO${}_4$crystals using different raw materials in a campaign to minimize impurities. We prepared the fused Al${}_2$O${}_3$ refractories for the growth of ingots. Purities of the grown crystals were measured with high purity germanium detectors and by inductively coupled plasma mass spectrometry. The results show that the Li${}_2$MoO${}_4$ crystal has purity levels suitable for rare-event experiments. In this study, we present the growth of Li${}_2$MoO${}_4$ crystals at CUP and their purities.