A neutron-energy dependent angular distribution was measured for individual $γ$-rays from the 3.2 eV $p$-wave resonance of $^{131}$Xe+$n$, that shows enhanced parity violation owing to a mixing between $s$- and $p$-wave amplitudes. The $γ$-ray transitions from the $p$-wave resonance were identified, and the angular distribution with respect to the neutron momentum was evaluated as a function of the neutron energy for 7132 keV $γ$-rays, which correspond to a transition to the 1807 keV excited state of $^{132}$Xe. The angular distribution is considered to originate from the interference between $s$- and $p$-wave amplitudes, and will provide a basis for a quantitative understanding of the enhancement mechanism of the fundamental parity violation in compound nuclei.

We describe a modular apparatus for use in parity-violation measurements in epithermal neutron-nucleus resonances with high instantaneous neutron fluxes at the Manuel Lujan Jr. Neutron Scattering Center at Los Alamos National Laboratory. This apparatus is designed to conduct high-precision measurements of the parity-odd transmission asymmetry of longitudinally polarized neutrons through targets containing nuclei with p-wave neutron-nucleus resonances in the 0.1-10 eV energy regime and to accommodate a future search for time reversal violation in polarized neutron transmission through polarized nuclear targets. The apparatus consists of an adjustable neutron and gamma collimation system, a He-3-He-4 ion chamber neutron flux monitor, two identical cryostats for target cooling, an adiabatic eV-neutron spin flipper, a near-unit efficiency Li-6-Li-7 scintillation detector operated in current mode, a flexible CAEN data acquisition system, and a neutron spin filter based on spin-exchange optical pumping of(3)He gas. We describe the features of the apparatus design devoted to the suppression of systematic errors in parity-odd asymmetry measurements. We describe the configuration of the apparatus used to conduct a precision measurement of parity violation at the 0.7 eV p-wave resonance in(139)La which employs two identical(139)La targets, one to polarize the beam on the p-wave resonance using the weak interaction and one to analyze the polarization.

The NIST neutron imaging program will build a new imaging instrument in the NCNR guide hall at the end of the neutron guide NG-6, beginning operation in summer of 2015. The NG-6 guide has a spectrum that is strongly peaked at a neutron wavelength of 0.5 nm, with a fluence rate of 2 x 10(9) cm(-2) s(-1) before a bismuth filter that is cooled by liquid nitrogen. The instrument will be developed in a phased manner and with an emphasis on maintaining a flexible space to conduct experiments and test new instrument concepts. In the initial phase of the instrument, the available space will permit a flight path of about 9 m, and will provide a platform for standard neutron radiography and tomography, wavelength selective imaging with a double crystal monochromator, and phase imaging based on a Talbot-Lau interferometer. The novel feature of the instrument will be the incorporation of Wolter optics to create a neutron microscope. Initially, prototype optics will be used in the microscope configuration to assess optic characteristics and image acquisition techniques. In the final form, the microscope will enable users to acquire images with similar to 10 mu m resolution 10-100x faster than current practice, and with a 10x magnifying optic to acquire images with similar to 1 mu m spatial resolution with image acquisition time similar to that for current images with similar to 10 mu m resolution. Published by Elsevier B.V.

The Low Energy Neutron Source (LENS) is a novel, university-based pulsed neutron source located within the Center for Explo- ration of Energy and Matter (CEEM) at Indiana University. The source utilizes a low energy p-n reaction in Beryllium coupled with a high-current, variable-pulse-width proton accelerator to produce either short or long neutron pulses. One of the target stations has been optimized for neutron radiation effects studies of device and board level electronics testing with quasi monochromatic high flux neutron beams (∼ 1 MeV equivalent silicon). The total neutron flux at the device under test (DUT) is approximately 2 · 1010 (n/cm2/sec) with low gamma contamination, 1 · 109 (n/cm2/sec). The neutron spectrum at the DUT position has been calculated using MCNP-X and has been characterized using foil activation measurements. In this paper we will describe the physical arrange-ment of the Device Test Area and indicate the unique features that have been incorporated to enhance testing effectiveness. We will also present the results of MCNP-X calculations with various adsorbed reflector arrangements that modify the spectrum incident on the device. Validation of the MCNP-X calculations using foil activation measurements will also be presented.

We have constructed a neutron imaging station at the Low Energy Neutron Source (LENS), located within the Center for the Exploration of Energy and Matter at Indiana University. In contrast to many existing neutron imaging stations, we utilize a broad range of neutron energies, extending into the fast neutron regime, to take advantage of the higher fluxes and larger penetrating power of these high-energy neutrons. The imaging station consists of a collimator to define the beam, a rotating sample stage, and a cooled charge-coupled device camera (Alta U6) using a scintillator. A LiF + ZnS screen is used to produce scintillation light. Typical image collection times are a few seconds for a aperture to sample distance ratio of 100, yielding a spatial resolution of 0.2 × 0.2 mm2. Examples of the scanned and calculated image are presented.

The Low-Energy Neutron Source (LENS) at Indiana University is a new class of pulsed neutron source, whose cost and scale are compatible with a University environment. This smaller scale supports missions that are vital to the health of neutron scattering in an environment increasingly dominated by large user facilities focused, of necessity, on serving the scientific needs of a broad scientific community. These missions include student education and development of new technologies to play as well as scientific investigations that are compatible with relatively low neutron flux. Since LENS first started producing neutrons (in 2005), this idea has been taken up in a number of other locations throughout the world, as exemplified in the formation of the Union of Compact Acceleratordriven Neutron Sources, which has already held two international meetings. LENS itself is now operating regularly with two scattering instruments at a beam power of 4kW, and these instruments are producing scientific results, educating many students at all levels, and providing a center for innovation in neutron instrumentation. Over the last two years, we have implemented changes to the RF power systems and beryllium target at the facility, and these changes have significantly enhanced beam reliability. In this summary, we will describe these changes to the facility design, and highlight a number of the important results that have arisen from our research, innovation, and educational activities over the last two years. .

The Indiana University Low Energy Neutron Source (LENS) production target was recently upgraded to handle the high power 13 MeV proton pulsed beam. The target, a 2 inch diameter beryllium disk, is 1.2 millimeters thick allowing the 13 MeV protons to pass completely through the target and stop in the cooling water eliminating the buildup of protons inside the beryllium. This change along with upgrading the cooling water system has produced the most reliable target to date for LENS operations. Details about the failure modes will be presented.

Indiana University is operating a Low Energy Neutron Source which provides cold neutrons for material research and neutron physics and MeV energy for the neutron radiation effects studies. Neutrons are being produced by a 13 MeV proton beam incident on a Beryllium target. The LENS Proton Delivery System (PDS) is routinely operating at 13 MeV and 25 mA at 1.8% duty factor. The RF system, consisting of three Litton 5773 klystron RF tubes at 425 MHz and 1 MW each, power the AccSys Technology PL-13 LINAC. The proton beam delivers up to 6 kilowatts of power to the Beryllium target. Details of the beam spreading system, target cooling system, and accelerator operations will be discussed.

The proton and deuteron analyzing powers and ten of the possible 12 spin correlation coefficients have been measured for p+d elastic scattering at proton bombarding energies of 135 and 200 MeV. The results are compared with Faddeev calculations using two different NN potentials. The qualitative features of the extensive data set on the spin dependence in p+d elastic scattering over a wide range of angles presented here are remarkably well explained by two-nucleon force predictions without inclusion of a three-nucleon force. The remaining discrepancies are, in general, not alleviated when theoretical three-nucleon forces are included in the calculations.

We discuss a new scheme to measure charged particle tracks in a large-volume detector. Such detectors are needed for the study of neutrino-induced reactions. The proposed detector consists of arrays of fluorescent fibers submersed in a tank of liquid scintillator. Analysis of the distribution of the light collected by fibers near a charged-particle track can be used to reconstruct the parameters of the track. We show that the results obtained with a simple prototype detector demonstrate that the proposed scheme is feasible.

A research program with the aim of investigating the spin dependence of the three nucelon continuum in (p) over right arrow (d) over right arrow collisions at intermediate energies was carried out at IUCF using the Polarized INternal Target EXperiments (PINTEX) facility. In the, elastic scattering experiment at 135 and 200 MeV proton beam energies a total of 15 independent spin observables were obtained. The breakup experiment was done with a vector and tensor polarized deuteron beam of 270 MeV and an internal polarized hydrogen gas target. We developed a novel technique for the analysis of the breakup observables, the sampling method. The new approach takes into account acceptance and non-uniformities of detection efficiencies and is suitable for any kinematically complete experiment with three particles in the final state.

Experimental results from the last five years showing that neutrinos oscillate and have mass have revolutionized how we think about neutrinos. This includes not only what their place is in the Standard Model, but also how we can use them to understand the universe. Can neutrinos also help us probe the smallest scales of matter, such as mapping out the spin structure of the nucleon? New high intensity beams and novel detection techniques have rekindled interest in neutrino scattering physics, allowing us to answer these questions. Described here is a detection technique for the FINeSSE experiment, designed to well measure low Q(2), v-p elastic scattering events, necessary to determine the spin carried by the strange quarks in the nucleon.

We have measured three axial polarization observables in d-->p--> breakup with a polarized 270 MeV deuteron beam on a polarized proton target. Axial observables are zero by parity conservation in elastic scattering but can be easily observed in the breakup channel at the present energy. Based on a symmetry argument, the sensitivity of these observables to the three-nucleon force might be enhanced. Calculations without three-nucleon force are in fair agreement with our measurement, indicating that the expected sensitivity of axial observables to the three-nucleon force is not confirmed. Including a three-nucleon force in the calculation does not improve the agreement with the data.

We have measured three axial polarization observables in (d) over right arrow(p) over right arrow breakup with a polarized 270 MeV deuteron beam on a polarized proton target. Axial observables are zero by parity conservation in elastic scattering but can be easily observed in the breakup channel at the present energy. Based on a symmetry argument, the sensitivity of these observables to the three-nucleon force might be enhanced. Calculations without three-nucleon force are in fair agreement with our measurement, indicating that the expected sensitivity of axial observables to the three-nucleon force is not confirmed. Including a three-nucleon force in the calculation does not improve the agreement with the data.

Understanding the quark and gluon substructure of the nucleon has been a prime goal of both nuclear and particle physics for more than thirty years and has led to much of the progress in strong interaction physics. Still the flavor dependence of the nucleon's spin is a significant fundamental question that is not understood. Experiments measuring the spin content of the nucleon have reported conflicting results on the amount of nucleon spin carried by strange quarks. Quasi-elastic neutrino scattering, observed using a novel detection technique, provides a theoretically clean measure of this quantity. The optimum neutrino beam energy needed to measure the strange spin of the nucleon is 1 GeV. This is also an ideal energy to search for neutrino oscillations at high $Δm^2$ in an astrophysically interesting region. Models of the r-process in supernovae which include high-mass sterile neutrinos may explain the abundance of neutron-rich heavy metals in the universe. These high-mass sterile neutrinos are outside the sensitivity region of any previous neutrino oscillation experiments. The Booster neutrino beamline at Fermilab provides the world's highest intensity neutrino beam in the 0.5-1.0 GeV energy range, a range ideal for both of these measurements. A small detector located upstream of the MiniBooNE detector, 100 m from the recently commissioned Booster neutrino source, could definitively measure the strange quark contribution to the nucleon spin. This detector, in conjunction with the MiniBooNE detector, could also investigate $ν_μ$ disappearance in a currently unexplored, cosmologically interesting region.

We have measured the vector and tensor polarization of an atomic deuterium target as a function of the target density. The polarized deuterium was produced in an atomic beam source and injected into a storage cell. For this experiment, the atomic beam source was operated without rf transitions, in order to avoid complications from the unknown efficiency of these transitions. In this mode, the atomic beam is vector and tensor polarized and both polarizations can be measured simultaneously. We used a 1.2-cm-diam and 27-cm-long storage cell, which yielded an average target density between 3 and 9 X 10(11) at/cm(3). We find that the tensor polarization decreases with increasing target density while the vector polarization remains constant. The data are in quantitative agreement with the calculated effect of spin exchange between deuterium atoms at low field.