Journal of Research of the National Institute of Standards and Technology articles from May 2005

Journal of Research of the National Institute of Standards and Technology archives from May 2005

Papers and posters presented at the April 2004 International Conference on Precision Measurements with Slow Neutrons at the National Institute of Standards and Technology.
May 1, 2005... Preface This Special Issue of the Journal of Research of the National Institute of Standards and Technology (Parts 1 and 2) contains papers from the International Conference on Precision Measurements with Slow Neutrons held at the National...

Precision Measurements with Slow Neutrons: April 5-7, 2004.(Department of Energy. Los Alamos National Laboratory's conference)(Illustration)
May 1, 2005... Program Sunday, April 4, 2004 -- Washingtonian Hotel 7:00 pm Reception Monday, April 5, 2004 -- NIST, Green Auditorium 9:00 am Opening Remarks--Dr. Lisa Karam, Acting Chief, Ionizing Radiation Division ...

Conference summary.(history and forecasts of neutron research)
May 1, 2005... The study of particle physics with low energy neutrons has a long history starting in the middle of the past century. During most of the time only a rather small number of researchers worked in this field, at least as compared to any of the...

The fundamental neutron physics facilities at NIST.
May 1, 2005... The program in fundamental neutron physics at the National Institute of Standards and Technology (NIST) began nearly two decades ago. The Neutron Interactions and Dosimetry Group currently maintains four neutron beam lines dedicated to studies...

New pulsed cold neutron beam line for fundamental nuclear physics at LANSCE.
May 1, 2005... The NPDGamma collaboration has completed the construction of a pulsed cold neutron beam line on flight path 12 at the Los Alamos Neutron Science Center (LANSCE). We describe the new beam line and characteristics of the beam. We report results...

The fundamental neutron physics beamline at the Spallation Neutron Source.
May 1, 2005... The Spallation Neutron Source (SNS), currently under construction at Oak Ridge National Laboratory with an anticipated start-up in early 2006, will provide the most intense pulsed beams of cold neutrons in the world. At a projected power of 1.4...

LENS: a new pulsed neutron source for research and education.
May 1, 2005... A new pulsed neutron source is under construction at the Indiana University Cyclotron Facility (IUCF). Neutrons are produced via (p,n) reactions by a low-energy proton beam incident on a thin beryllium target. The source is tightly coupled to a...

Simulation of the performance of a fundamental neutron physics beamline at the High Flux Isotope Reactor.
May 1, 2005... We study the expected performance of the proposed fundamental neutron physics beamline at the upgraded High Flux Isotope Reactor at Oak Ridge National Laboratory. A curved neutron guide transmits the neutrons from the new cold source into a...

Beamline performance simulations for the fundamental neutron physics beamline at the Spallation Neutron Source.
May 1, 2005... Monte Carlo simulations are being performed to design and characterize the neutron optics components for the two fundamental neutron physics beamlines at the Spallation Neutron Source. Optimization of the cold beamline includes characterization...

Search for a neutron electric dipole moment.
May 1, 2005... The possible existence of a nonzero electric dipole moment (EDM) of the neutron is of great fundamental interest in itself and directly impacts our understanding of the nature of electro-weak and strong interactions. The experimental search for...

Magnetic field stabilization for magnetically shielded volumes by external field coils.
May 1, 2005... For highly sensitive magnetic measurements, e.g., a measurement of the neutron electric dipole moment (EDM), the magnetic field has to be stable in time on a level below picoTesla. One of several measures we employ to achieve this uses an...

Design and performance of laser-pumped Cs-magnetometers for the planned UCN EDM experiment at PSI.
May 1, 2005... We designed laser-pumped cesium vapor magnetometers in the [M.sub.x] configuration for the control and stabilization of magnetic field fluctuations and gradients in a new experiment searching for a permanent electric dipole moment of the...

Superconducting UCN polarizer for a new EDM spectrometer.
May 1, 2005... A test experiment has shown that the number of ultracold neutrons (UCN) of one polarization state, transmitted through a 100 [micro]m Al foil when placed in a 5 T magnetic field, is greater by 3.8 times. The increased transmission is due to the...

Neutron measurements and the weak nucleon-nucleon interaction.
May 1, 2005... The weak interaction between nucleons remains one of the most poorly-understood sectors of the Standard Model. A quantitative description of this interaction is needed to understand weak interaction phenomena in atomic, nuclear, and hadronic...

Measurement of parity violation in np capture: the NPDGamma experiment.
May 1, 2005... The NPDGamma experiment will measure the parity-violating directional gamma ray asymmetry [A.sub.[gamma]] in the reaction [[right arrow].n] + p [right arrow] d + [gamma]. Ultimately, this will constitute the first measurement in the...

Measurement of the parity-violating neutron spin rotation in [.sup.4]He.
May 1, 2005... In the meson exchange model of weak nucleon-nucleon (NN) interactions, the exchange of virtual mesons between the nucleons is parameterized by a set of weak meson exchange amplitudes. The strengths of these amplitudes from theoretical...

Parity-violating neutron spin rotation in a liquid parahydrogen target.
May 1, 2005... Our understanding of hadronic parity violation is far from clear despite nearly 50 years of theoretical and experimental progress. Measurements of low-energy parity-violating observables in nuclear systems are the only accessible means to study...

Commissioning of the NPDGamma detector array: counting statistics in current mode operation and parity violation in the capture of cold neutrons on [B.sub.4]C and [.sup.27]Al.
May 1, 2005... The NPDGamma [gamma]-ray detector has been built to measure, with high accuracy, the size of the small parity-violating asymmetry in the angular distribution of gamma rays from the capture of polarized cold neutrons by protons. The high cold...

A gamma polarimeter for neutron polarization measurement in a liquid deuterium target for parity violation in polarized neutron capture on deuterium.
May 1, 2005... A measurement of the parity-violating gamma asymmetry in n-D capture would yield information on N-N parity violation independent of the n-p system. Since cold neutrons will depolarize in a liquid deuterium target in which the scattering cross...

Direct nn-scattering measurement with the pulsed reactor YAGUAR.
May 1, 2005... Although crucial for resolving the issue of charge symmetry in the nuclear force, direct measurement of nn-scattering by colliding free neutrons has never been performed. At present the Russian pulsed reactor YAGUAR is the best neutron source...

SUSANS with polarized neutrons.(Super Ultra-Small Angle Neutron Scattering)
May 1, 2005... Super Ultra-Small Angle Neutron Scattering (SUSANS) studies over wave vector transfers of [10.sup.-4] [nm.sup.-1] to [10.sup.-3] [nm.sup.-1] afford information on micrometer-size agglomerates in samples. Using a right-angled magnetic air prism,...

High-precision determination of the neutron coherent scattering length.
May 1, 2005... The neutron coherent scattering length [b.sub.c] has been determined interferometrically to an uncertainty of about 5 X [10.sup.-5] by measuring the nondispersive phase. We propose improving the uncertainty to about [10.sup.-6] by optimizing...

Measurement of the coherent neutron scattering length of [.sup.3]He.
May 1, 2005... By means of neutron interferometry the s-wave neutron scattering length of the [.sup.3]He nucleus was re-measured at the Institut Laue-Langevin (ILL). Using a skew symmetrical perfect crystal Si-interferometer and a linear twin chamber cell,...

Observation on the visibility decrease in a VCN spin resonator interferometry.
May 1, 2005... The present paper reports on the detailed studies concerning the neutron spin interference visibility observed after transmitting through multilayer magnetic resonators in a spin echo condition with very cold neutrons from a high flux reactor....

Spatial non-cyclic geometric phase in neutron interferometry.
May 1, 2005... We present a split-beam neutron interferometric experiment to test the non-cyclic geometric phase tied to the spatial evolution of the system: the subjacent two-dimensional Hilbert space is spanned by the two possible paths in the...

Virtual excitation and multiple scattering correction terms to the neutron index of refraction for hydrogen.
May 1, 2005... The neutron index of refraction is generally derived theoretically in the Fermi approximation. However, the Fermi approximation neglects the effects of the binding of the nuclei of a material as well as multiple scattering. Calculations by...

Investigation of the neutron quantum states in the Earth's gravitational field.
May 1, 2005... We studied the neutron quantum states in the potential well formed by the Earth's gravitational field and a horizontal mirror. The estimated characteristic sizes of the neutron wave functions in two lowest quantum states correspond to their...

Constraints on non-Newtonian gravity from the experiment on neutron quantum states in the Earth's gravitational field.
May 1, 2005... An upper limit to non-Newtonian attractive forces is obtained from the measurement of quantum states of neutrons in the Earth's gravitational field. This limit improves the existing constraints in the nanometer range. Key words: neutron...

UCN production with a single crystal of ortho-deuterium.
May 1, 2005... The present paper reports on the preliminary experimental results concerning a new concept of ultracold neutron production with a single crystal converter of ortho-deuterium lying in the ground rotational state at the low temperature of about...

Measurement of the loss and depolarization probability of UCN on Beryllium and diamond like carbon films.(ultracold neutron)
May 1, 2005... Currently several institutes worldwide are working on the development of a new generation of ultracold neutron (UCN) sources. In parallel with source development, new materials for guiding and storage of UCN are developed. Currently the best...

First tests of [.sup.6]Li doped glass scintillators for ultracold neutron detection.
May 1, 2005... We report the results of test measurements aimed at determining the performances of [.sup.6]Li doped glass scintillators for the detection of ultra-cold neutrons. Four types of scintillators, GS1, GS3, GS10 and GS20, which differ by their...

A silicon UCN detector with large area and with analysis of UCN polarization.(ultracold neutron)
May 1, 2005... A silicon ultracold neutron (UCN) detector with an area of 45 [cm.sup.2] and with a [.sup.6]LiF converter is developed at St. Petersburg Nuclear Physics Institute (PNPI). The spectral efficiency of the silicon UCN detector was measured by means...

[.sup.3]He spin filter for neutrons.(neutron polarization analysis)
May 1, 2005... The strongly spin-dependent absorption of neutrons in nuclear spin-polarized [.sup.3]He opens up the possibility of polarizing neutrons from reactors and spallation sources over the full kinematical range of cold, thermal and hot neutrons. This...

Polarized [.sup.3]He spin filters for slow neutron physics.
May 1, 2005... Polarized [.sup.3]He spin filters are needed for a variety of experiments with slow neutrons. Their demonstrated utility for highly accurate determination of neutron polarization are critical to the next generation of betadecay correlation...

A new method for precision cold neutron polarimetry using a [.sup.3]He spin filter.
May 1, 2005... We present a new method for precision measurement of the capture flux polarization of a polychromatic (white), continuous cold neutron beam, polarized by a [.sup.3]He spin filter. This method allows an in situ measurement and does not require...

Precision neutron polarimetry for neutron beta decay.
May 1, 2005... The abBA collaboration is developing a new type of field-expansion spectrometer for a measurement of the three correlation coefficients a, A, and B and the shape parameter b. The measurement of A and B requires precision neutron polarimetry. We...