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- Neutrons (2)
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Articles 1 - 30 of 34
Full-Text Articles in Physics
Ion Beams In Multi-Species Plasma, Evan M. Aguirre, Earl E. Scime, Timothy N. Good
Ion Beams In Multi-Species Plasma, Evan M. Aguirre, Earl E. Scime, Timothy N. Good
Physics and Astronomy Faculty Publications
Argon and xenon ion velocity distribution functions are measured in Ar-He, Ar-Xe, and Xe-He expanding helicon plasmas to determine if ion beam velocity is enhanced by the presence of lighter ions. Contrary to observations in mixed gas sheath experiments, we find that adding a lighter ion does not increase the ion beam speed. The predominant effect is a reduction of ion beam velocity consistent with increased drag arising from increased gas pressure under all conditions: constant total gas pressure, equal plasma densities of different ions, and very different plasma densities of different ions. These results suggest that the physics responsible …
Slotted Rotatable Target Assembley And Systematic Error Analysis For A Search For Long Range Spin Dependent Interactions From Exotic Vector Boson Exchange Using Neutron Spin Rotation, C. Haddock, Bret E. Crawford, W. Fox, I. Francis, A. T. Holley, Scott W. Magers, M. Sarsour, W. M. Snow, J. Vanderwerp
Slotted Rotatable Target Assembley And Systematic Error Analysis For A Search For Long Range Spin Dependent Interactions From Exotic Vector Boson Exchange Using Neutron Spin Rotation, C. Haddock, Bret E. Crawford, W. Fox, I. Francis, A. T. Holley, Scott W. Magers, M. Sarsour, W. M. Snow, J. Vanderwerp
Physics and Astronomy Faculty Publications
We discuss the design and construction of a novel target array of nonmagnetic test masses used in a neutron polarimetry measurement made in search for new possible exotic spin dependent neutron–atominteractions of Nature at sub-mm length scales. This target was designed to accept and efficiently transmit a transversely polarized slow neutron beam through a series of long open parallel slots bounded by flat rectangular plates. These openings possessed equal atom density gradients normal to the slots from the flat test masses with dimensions optimized to achieve maximum sensitivity to an exotic spin-dependent interaction from vector boson exchanges with ranges in …
Neutron-Unbound Excited States Of 23n, M. Jones, T. Baumann, J. Brett, J. Bullaro, P. A. Deyoung, J.E. Finck, N. Frank, K. Hammerton, J. Hinnefeld, Z. Kohley, A. N. Kuchera, J. Pereira, A. Rabeh, J. K. Smith, A. Spyrou, Sharon L. Stephenson, K. Stiefel, M. Tuttle-Timm, R. G.T. Zegers, M. Thoennessen
Neutron-Unbound Excited States Of 23n, M. Jones, T. Baumann, J. Brett, J. Bullaro, P. A. Deyoung, J.E. Finck, N. Frank, K. Hammerton, J. Hinnefeld, Z. Kohley, A. N. Kuchera, J. Pereira, A. Rabeh, J. K. Smith, A. Spyrou, Sharon L. Stephenson, K. Stiefel, M. Tuttle-Timm, R. G.T. Zegers, M. Thoennessen
Physics and Astronomy Faculty Publications
Neutron unbound states in 23N were populated via proton knockout from an 83.4 MeV/nucleon 24O beam on a liquid deuterium target. The two-body decay energy displays two peaks at E1∼100keV and E2∼1MeV with respect to the neutron separation energy. The data are consistent with shell model calculations predicting resonances at excitation energies of ∼3.6MeV and ∼4.5MeV. The selectivity of the reaction implies that these states correspond to the first and second 3/2− states. The energy of the first state is about 1.3 MeV lower than the first excited 2+ in 24O. This decrease is largely due to coupling with the …
Neutron Correlations In The Decay Of The First Excited State Of 11li, Jenna K. Smith, Thomas J. Baumann, Daniel Bazin, James Brown, Paul A. Deyoung, Nathan H. Frank, Michael D. Jones, Zack Kohley, Bryan A. Luther, B. S. Marks, Artemis Spyrou, Sharon L. Stephenson, Michael R. Thoennessen, Alexander S. Volya
Neutron Correlations In The Decay Of The First Excited State Of 11li, Jenna K. Smith, Thomas J. Baumann, Daniel Bazin, James Brown, Paul A. Deyoung, Nathan H. Frank, Michael D. Jones, Zack Kohley, Bryan A. Luther, B. S. Marks, Artemis Spyrou, Sharon L. Stephenson, Michael R. Thoennessen, Alexander S. Volya
Physics and Astronomy Faculty Publications
The decay of unbound excited 11Li was measured after being populated by a two-proton removal from a 13B beam at 71 MeV/nucleon. Decay energy spectra and Jacobi plots were obtained from measurements of the momentum vectors of the 9Li fragment and neutrons. A resonance at an excitation energy of ∼1.2 MeV was observed. The kinematics of the decay are equally well fit by a simple dineutron-like model or a phase-space model that includes final state interactions. A sequential decay model can be excluded.
Search For 4n Contributions In The Reaction 14be(Ch2,X)10he, Michael D. Jones, Zack Kohley, Thomas J. Baumann, Greg Christian, Paul A. Deyoung, Joseph E. Finck, Nathan H. Frank, Robert A. Haring-Kaye, A. N. Kuchera, Bryan A. Luther, Shea Mosby, Jenna K. Smith, J. Snyder, Artemis Spyrou, Sharon L. Stephenson, Michael R. Thoennessen
Search For 4n Contributions In The Reaction 14be(Ch2,X)10he, Michael D. Jones, Zack Kohley, Thomas J. Baumann, Greg Christian, Paul A. Deyoung, Joseph E. Finck, Nathan H. Frank, Robert A. Haring-Kaye, A. N. Kuchera, Bryan A. Luther, Shea Mosby, Jenna K. Smith, J. Snyder, Artemis Spyrou, Sharon L. Stephenson, Michael R. Thoennessen
Physics and Astronomy Faculty Publications
A previously published measurement of the ground state resonance of 10He, populated by a reaction of a 59 MeV/u 14Be beam on a deuterated polyethylene target, was further analyzed to search for 4n emission resulting from 2p removal. No evidence for 4n events was found. A lower limit of about 1 MeV was determined for a possible resonance in 12He.
Two-Neutron Sequential Decay Of 24o, M. D. Jones, N. Frank, T. Baumann, J. Brett, J. Bullaro, P. A. Deyoung, J.E. Finck, K. Hammerton, J. Hinnefeld, Z. Kohley, A. N. Kuchera, J. Pereira, A. Rabeh, W. F. Rogers, J. K. Smith, A. Spyrou, Sharon L. Stephenson, K. Stiefel, M. Tuttle-Timm, R. G.T. Zegers, M. Thoennessen
Two-Neutron Sequential Decay Of 24o, M. D. Jones, N. Frank, T. Baumann, J. Brett, J. Bullaro, P. A. Deyoung, J.E. Finck, K. Hammerton, J. Hinnefeld, Z. Kohley, A. N. Kuchera, J. Pereira, A. Rabeh, W. F. Rogers, J. K. Smith, A. Spyrou, Sharon L. Stephenson, K. Stiefel, M. Tuttle-Timm, R. G.T. Zegers, M. Thoennessen
Physics and Astronomy Faculty Publications
A two-neutron unbound excited state of 24O was populated through a (d,d ) reaction at 83.4 MeV/nucleon. A state at E = 715 ± 110 (stat) ± 45 (sys) keV with a width of < 2 MeV was observed above the two-neutron separation energy placing it at 7.65 ± 0.2 MeV with respect to the ground state. Three-body correlations for the decay of 24O → 22O + 2n show clear evidence of a sequential decay through an intermediate state in 23O. Neither a di-neutron nor phase-space model for the three-body breakup were able to describe these correlations.
Population Of 13be In A Nucleon Exchange Reaction, B. R. Marks, P. A. Deyoung, J. K. Smith, T. Baumann, J. Brown, N. Frank, J. Hinnefeld, M. Hoffman, M. D. Jones, Z. Kohley, A. N. Kuchera, B. Luther, A. Spyrou, Sharon L. Stephenson, C. Sullivan, M. Thoennessen, N. Viscariello, S. J. Williams
Population Of 13be In A Nucleon Exchange Reaction, B. R. Marks, P. A. Deyoung, J. K. Smith, T. Baumann, J. Brown, N. Frank, J. Hinnefeld, M. Hoffman, M. D. Jones, Z. Kohley, A. N. Kuchera, B. Luther, A. Spyrou, Sharon L. Stephenson, C. Sullivan, M. Thoennessen, N. Viscariello, S. J. Williams
Physics and Astronomy Faculty Publications
The neutron-unbound nucleus Be13 was populated with a nucleon exchange reaction from a 71 MeV/u secondary B13 beam. The decay-energy spectrum was reconstructed using invariant mass spectroscopy based on Be12 fragments in coincidence with neutrons. The data could be described with an s-wave resonance at Er=0.73(9)MeV with a width of Γr=1.98(34)MeVand a d-wave resonance at Er=2.56(13)MeV with a width of Γr=2.29(73)MeV. The observed spectral shape is consistent with previous one-proton removal reaction measurements from B14.
A Slow Neutron Polarimeter For The Measurement Of Parity-Odd Neutron Rotary Power, W. M. Snow, E. Anderson, L. Barron-Palos, C. D. Bass, T. D. Bass, Bret E. Crawford, C. Crawford, J. M. Dawkins, D. Esposito, J. Fry, H. Gardiner, K. Gan, C. Haddock, B. R. Heckel, A. T. Holley, J. C. Horton, C. Huffer, J. Lieffers, D. Luo, M. Maldonado-Velazquez, D. M. Markoff, A. M. Micherdzinska, H. P. Mumm, J. S. Nico, M. Sarsour, S. Santra, E. I. Sharapov, H. E. Swanson, S. B. Walbridge, V. Zhumabekova
A Slow Neutron Polarimeter For The Measurement Of Parity-Odd Neutron Rotary Power, W. M. Snow, E. Anderson, L. Barron-Palos, C. D. Bass, T. D. Bass, Bret E. Crawford, C. Crawford, J. M. Dawkins, D. Esposito, J. Fry, H. Gardiner, K. Gan, C. Haddock, B. R. Heckel, A. T. Holley, J. C. Horton, C. Huffer, J. Lieffers, D. Luo, M. Maldonado-Velazquez, D. M. Markoff, A. M. Micherdzinska, H. P. Mumm, J. S. Nico, M. Sarsour, S. Santra, E. I. Sharapov, H. E. Swanson, S. B. Walbridge, V. Zhumabekova
Physics and Astronomy Faculty Publications
We present the design, description, calibration procedure, and an analysis of systematic effects for an apparatus designed to measure the rotation of the plane of polarization of a transversely polarized slow neutron beam as it passes through unpolarized matter. This device is the neutronoptical equivalent of a crossed polarizer/analyzer pair familiar from light optics. This apparatus has been used to search for parity violation in the interaction of polarized slow neutrons in matter. Given the brightness of existing slow neutron sources, this apparatus is capable ofmeasuring a neutron rotary power of dϕ/dz = 1 × 10−7 rad/m.
Low-Lying Neutron Unbound States In 12be, J. K. Smith, T. Baumann, D. Bazin, J. Brown, S. Casarotto, P. A. Deyoung, N. Frank, J. Hinnefeld, M. Hoffman, M. D. Jones, Z. Kohley, B. Luther, B. Marks, N. Smith, J. Snyder, A. Spyrou, Sharon L. Stephenson, M. Thoennessen, N. Viscariello, S. J. Williams
Low-Lying Neutron Unbound States In 12be, J. K. Smith, T. Baumann, D. Bazin, J. Brown, S. Casarotto, P. A. Deyoung, N. Frank, J. Hinnefeld, M. Hoffman, M. D. Jones, Z. Kohley, B. Luther, B. Marks, N. Smith, J. Snyder, A. Spyrou, Sharon L. Stephenson, M. Thoennessen, N. Viscariello, S. J. Williams
Physics and Astronomy Faculty Publications
The neutron decay of an unbound resonance in 12Be has been measured at 1243 ± 21 keV decay energy with a width of 634 ± 60 keV. This state was populated with a one-proton removal reaction from a 71 MeV/u 13B beam incident upon a beryllium target. The invariant mass reconstruction of the resonance was achieved by measuring the daughter fragment in coincidence with neutrons. Despite being above the 2n separation energy, the state decays predominantly by the emission of one neutron to 11Be, setting an upper limit on the branching ratio for the two-neutron decay channel to 10Be of …
Unresolved Question Of The 10he Ground State Resonance, Z. Kohley, J. Snyder, T. Baumann, G. Christian, P.A. Deyoung, J.E. Finck, R.A. Haring-Kaye, M. Jones, E. Lunderberg, B. Luther, S. Mosby, A. Simon, J.K. Smith, A. Spyrou, Sharon L. Stephenson, M. Thoennessen
Unresolved Question Of The 10he Ground State Resonance, Z. Kohley, J. Snyder, T. Baumann, G. Christian, P.A. Deyoung, J.E. Finck, R.A. Haring-Kaye, M. Jones, E. Lunderberg, B. Luther, S. Mosby, A. Simon, J.K. Smith, A. Spyrou, Sharon L. Stephenson, M. Thoennessen
Physics and Astronomy Faculty Publications
The group state of 10He was populated using a 2p2n-removal from a 59 MeV/u 14Be beam. The decay energy of the three body system, 8He + n + n, was measured and a resonance was observed at E = 1.60(25) MeV with a 1.8(4) MeV width. This result is in agreement with previous invariant mass spectroscopy measurements, using the 11Li(-p) reaction, but is consistent with recent transfer reaction results. The proposed explanation that the difference, about 500 keV, is due to the effect of the extended halo nature of 11Li in the one-proton knockout reaction is …
Bulk Properties Of A Fermi Gas In A Magnetic Field, Michael T. Strickland, Veronica Dexheimer, D.P. Menezes
Bulk Properties Of A Fermi Gas In A Magnetic Field, Michael T. Strickland, Veronica Dexheimer, D.P. Menezes
Physics and Astronomy Faculty Publications
We calculate the number density, energy density, transverse pressure, longitudinal pressure and magnetization of an ensemble of spin one-half particles in the presence of a homogeneous background magnetic field. The magnetic field direction breaks spherical symmetry causing the pressure parallel to it. We present explicit formulae appropriate at zero and finite temperature for both charged and uncharged particles including the effect of the anomalous magnetic moment. We demonstrate that the resulting expressions satisfy the canonical relations, omega = -PII and Pperpendicular = PII- MB with M = (delta)(omega)/(delta)(beta) being the magnetization of the system. We numerically …
Local Origins Of Volume Fraction Fluctuations In Dense Granular Materials, James G. Puckett, Frederic Lechenault, Karen E. Daniels
Local Origins Of Volume Fraction Fluctuations In Dense Granular Materials, James G. Puckett, Frederic Lechenault, Karen E. Daniels
Physics and Astronomy Faculty Publications
Fluctuations of the local volume fraction within granular materials have previously been observed to decrease as the system approaches jamming.We experimentally examine the role of boundary conditions and interparticle friction μ on this relationship for a dense granular material of bidisperse particles driven under either constant volume or constant pressure.Using a radicalVorono¨ı tessellation, we find the variance of the local volume fraction φ monotonically decreases as the system becomes more dense, independent of boundary condition and μ. We examine the universality and origins of this trend using experiments and the recent granocentric model, modified to draw particle locations from an …
Reconstructing Three-Dimensional Shape Envelopes From Time-Resolved Small-Angle X-Ray Scattering Data, Jessica Lamb, Lisa W. Kwok, Xiangyun Qiu, Kurt Andresen, Hye Yoon Park, Lois Pollack
Reconstructing Three-Dimensional Shape Envelopes From Time-Resolved Small-Angle X-Ray Scattering Data, Jessica Lamb, Lisa W. Kwok, Xiangyun Qiu, Kurt Andresen, Hye Yoon Park, Lois Pollack
Physics and Astronomy Faculty Publications
Modern computing power has made it possible to reconstruct low-resolution, three-dimensional shapes from solution small-angle X-ray scattering (SAXS) data on biomolecules without a priori knowledge of the structure. In conjunction with rapid mixing techniques, SAXS has been applied to time resolve conformational changes accompanying important biological processes, such as biomolecular folding. In response to the widespread interest in SAXS reconstructions, their value in conjunction with such time-resolved data has been examined. The group I intron from Tetrahymena thermophila and its P4–P6 subdomain are ideal model systems for investigation owing to extensive previous studies, including crystal structures. The goal of this …
Focusing Capillary Optics For Use In Solution Small-Angle X-Ray Scattering, Jessica S. Lamb, Sterling Cornaby, Kurt Andresen, Lisa W. Kwok, Hye Yoon Park, Xiangyun Qiu, Detlef-M. Smilgies, Donald H. Bilderback, Lois Pollack
Focusing Capillary Optics For Use In Solution Small-Angle X-Ray Scattering, Jessica S. Lamb, Sterling Cornaby, Kurt Andresen, Lisa W. Kwok, Hye Yoon Park, Xiangyun Qiu, Detlef-M. Smilgies, Donald H. Bilderback, Lois Pollack
Physics and Astronomy Faculty Publications
Measurements of the global conformation of macromolecules can be carried out using small-angle X-ray scattering (SAXS). Glass focusing capillaries, manufactured at the Cornell High Energy Synchrotron Source (CHESS), have been successfully employed for SAXS measurements on the heme protein cytochrome c. These capillaries provide high X-ray flux into a spot size of tens of micrometres, permitting short exposures of small-volume samples. Such a capability is ideal for use in conjunction with microfluidic mixers, where time resolution may be determined by beam size and sample volumes are kept small to facilitate mixing and conserve material.
Parity Violation In Neutron Resonances Of Palladium, D A. Smith, J D. Bowman, Bret E. Crawford, C A. Grossmann, T Haseyama, A Masaike, Y Matsuda, G E. Mitchell, S I. Penttila, N R. Roberson, S J. Seestrom, E I. Sharapov, Sharon L. Stephenson, V W. Yuan
Parity Violation In Neutron Resonances Of Palladium, D A. Smith, J D. Bowman, Bret E. Crawford, C A. Grossmann, T Haseyama, A Masaike, Y Matsuda, G E. Mitchell, S I. Penttila, N R. Roberson, S J. Seestrom, E I. Sharapov, Sharon L. Stephenson, V W. Yuan
Physics and Astronomy Faculty Publications
Parity violation in p-wave neutron resonances of the palladium isotopes 104, 105, 106, and 108 has been measured by transmission of a longitudinally polarized neutron beam through a natural palladium target. The measurements were performed at the pulsed spallation neutron source of Los Alamos Neutron Science Center. The rms weak interaction matrix elements and the corresponding spreading widths were determined for 104 Pd, 105 Pd, and 106 Pd
Neutron Resonance Spectroscopy Of 104pd, 105pd, And 110pd, J D. Bowman, D A. Smith, Bret E. Crawford, T Haseyama, C A. Grossmann, A Masaike, Y Matsuda, G E. Mitchell, S I. Penttila, N R. Roberson, S J. Seestrom, E I. Sharapov, Sharon L. Stephenson, V W. Yuan, A M. Sukhovoj
Neutron Resonance Spectroscopy Of 104pd, 105pd, And 110pd, J D. Bowman, D A. Smith, Bret E. Crawford, T Haseyama, C A. Grossmann, A Masaike, Y Matsuda, G E. Mitchell, S I. Penttila, N R. Roberson, S J. Seestrom, E I. Sharapov, Sharon L. Stephenson, V W. Yuan, A M. Sukhovoj
Physics and Astronomy Faculty Publications
We have measured neutron resonances in the palladium isotopes 104, 105, and 110 for neutron energies from 1 to 2100 eV. Many new p-wave resonances have been observed. Their neutron widths and, in several cases, the radiative widths were measured. The average level spacings and the s-wave and p-wave neutron strength functions were determined. The time-of-flight method was used for both neutron total cross section measurements and total (n,γ) reaction yield measurements at the pulsed spallation neutron source of Los Alamos Neutron Science Center. Well established resonance spectroscopy for these isotopes is essential for the analysis of parity violation data …
Parity Violation In Neutron Resonances Of Antimony And Iodine, Y Matsuda, J D. Bowman, Bret E. Crawford, P P J. Delheij, T Haseyama, J N. Knudsen, L Y. Lowie, A Masaike, G E. Mitchell, S I. Penttila, H Postma, N R. Roberson, S J. Seestrom, E I. Sharapov, Sharon L. Stephenson, Y-F Yen, V W. Yuan
Parity Violation In Neutron Resonances Of Antimony And Iodine, Y Matsuda, J D. Bowman, Bret E. Crawford, P P J. Delheij, T Haseyama, J N. Knudsen, L Y. Lowie, A Masaike, G E. Mitchell, S I. Penttila, H Postma, N R. Roberson, S J. Seestrom, E I. Sharapov, Sharon L. Stephenson, Y-F Yen, V W. Yuan
Physics and Astronomy Faculty Publications
Parity violation in p-wave neutron resonances of 121Sb, 123Sb, and 127I has been measured by transmission of a longitudinally polarized neutron beam through natural antimony and iodine targets. The measurements were performed at the pulsed spallation neutron source of the Los Alamos Neutron Science Center. Five statistically significant parity violation effects were observed in 121Sb, one effect in 123Sb, and seven effects in 127I. The weak interaction rms matrix elements and the corresponding spreading widths were determined.
Parity Violation In Neutron Resonances Of 117 Sn, D A. Smith, J D. Bowman, Bret E. Crawford, C A. Grossmann, T Haseyama, Mikkel B. Johnson, A Masaike, Y Matsuda, G E. Mitchell, V A. Nazarenko, S I. Penttila, N R. Roberson, S J. Seestrom, E I. Sharapov, L M. Smotritsky, Sharon L. Stephenson, S Tomsovic, V W. Yuan
Parity Violation In Neutron Resonances Of 117 Sn, D A. Smith, J D. Bowman, Bret E. Crawford, C A. Grossmann, T Haseyama, Mikkel B. Johnson, A Masaike, Y Matsuda, G E. Mitchell, V A. Nazarenko, S I. Penttila, N R. Roberson, S J. Seestrom, E I. Sharapov, L M. Smotritsky, Sharon L. Stephenson, S Tomsovic, V W. Yuan
Physics and Astronomy Faculty Publications
Parity nonconservation (PNC) has been studied in neutron p-wave resonances of 117Sn. The longitudinal asymmetries were measured for 29 p-wave resonances in the neutron energy range 0.8 eV to 1100 eV. Statistically significant PNC effects were observed for four resonances. A statistical analysis determined the rms weak mixing matrix element and the weak spreading width. A weak spreading width of Γw=(0.28-0.15+0.56)×10-7 eV was obtained for117Sn.
New Search For Parity Violation In Nonresonant Neutron Scattering On Thorium, J D. Bowman, Bret E. Crawford, P P J. Delheij, C M. Frankle, M Iinuma, J N. Knudsen, L Y. Lowie, A Masaike, Y Matsuda, S I. Penttila, H Postma, N R. Roberson, S J. Seestrom, E I. Sharapov, Sharon L. Stephenson, Y-F Yen, V W. Yuan
New Search For Parity Violation In Nonresonant Neutron Scattering On Thorium, J D. Bowman, Bret E. Crawford, P P J. Delheij, C M. Frankle, M Iinuma, J N. Knudsen, L Y. Lowie, A Masaike, Y Matsuda, S I. Penttila, H Postma, N R. Roberson, S J. Seestrom, E I. Sharapov, Sharon L. Stephenson, Y-F Yen, V W. Yuan
Physics and Astronomy Faculty Publications
The parity-violating longitudinal asymmetry of the neutron scattering cross section has been measured for thorium in the off-resonance energy intervals from 30 to 300 eV. The observed result of (0.5±1.6)×10-6 is compared with theoretical predictions.
Parity Violation In Neutron Resonances In 115in, Sharon L. Stephenson, J D. Bowman, J Corvi, Bret E. Crawford, P P J. Delheij, C M. Frankle, M Iinuma, J N. Knudsen, L Y. Lowie, A Masaike, Y Matsuda, G E. Mitchell, S I. Penttila, H Postma, N R. Roberson, S J. Seestrom, E I. Sharapov, H M. Shimizu, Y-F Yen, V W. Yuan, L Zanini
Parity Violation In Neutron Resonances In 115in, Sharon L. Stephenson, J D. Bowman, J Corvi, Bret E. Crawford, P P J. Delheij, C M. Frankle, M Iinuma, J N. Knudsen, L Y. Lowie, A Masaike, Y Matsuda, G E. Mitchell, S I. Penttila, H Postma, N R. Roberson, S J. Seestrom, E I. Sharapov, H M. Shimizu, Y-F Yen, V W. Yuan, L Zanini
Physics and Astronomy Faculty Publications
Parity nonconservation (PNC) was studied in p-wave resonances in indium by measuring the helicity dependence of the neutron total cross section in the neutron energy range 6.0–316 eV with the time-of-flight method at LANSCE. A total of 36 p-wave neutron resonances were studied in 115In, and statistically significant asymmetries were observed for nine cases. An analysis treating the PNC matrix elements as random variables yields a weak matrix element of M=(0.67-0.12+0.16) meV and a weak spreading width of Γw=(1.30-0.43+0.76)×10-7 eV.
Parity Violation In 232th Neutron Resonances Above 250 Ev, E I. Sharapov, J D. Bowman, Bret E. Crawford, P P J. Delheij, C M. Frankle, M Iinuma, J N. Knudsen, L Y. Lowie, J E. Lynch, A Masaike, Y Matsuda, G E. Mitchell, S I. Penttila, H Postma, N R. Roberson, S J. Seestrom, Sharon L. Stephenson, Y-F Yen, V W. Yuan
Parity Violation In 232th Neutron Resonances Above 250 Ev, E I. Sharapov, J D. Bowman, Bret E. Crawford, P P J. Delheij, C M. Frankle, M Iinuma, J N. Knudsen, L Y. Lowie, J E. Lynch, A Masaike, Y Matsuda, G E. Mitchell, S I. Penttila, H Postma, N R. Roberson, S J. Seestrom, Sharon L. Stephenson, Y-F Yen, V W. Yuan
Physics and Astronomy Faculty Publications
The analysis of parity nonconservation (PNC) measurements performed on 232Th by the TRIPLE Collaboration has been extended to include the neutron energy range of 250 to 1900 eV. Below 250 eV all ten statistically significant parity violations have the same sign. However, at higher energies PNC effects of both signs were observed in the transmission of longitudinally polarized neutrons through a thick thorium target. Although the limited experimental energy resolution precluded analysis in terms of the longitudinal asymmetry, parity violations were observed and the cross section differences for positive and negative neutron helicities were obtained. For comparison, a similar …
Parity Nonconservation In 106pd And 108pd Neutron Resonances, Bret E. Crawford, J D. Bowman, P P J. Delheij, T Haseyama, J N. Knudsen, L Y. Lowie, A Masaike, Y Matsuda, G E. Mitchell, S I. Penttila, H Postma, N R. Roberson, S J. Seestrom, E I. Sharapov, Sharon L. Stephenson, V W. Yuan
Parity Nonconservation In 106pd And 108pd Neutron Resonances, Bret E. Crawford, J D. Bowman, P P J. Delheij, T Haseyama, J N. Knudsen, L Y. Lowie, A Masaike, Y Matsuda, G E. Mitchell, S I. Penttila, H Postma, N R. Roberson, S J. Seestrom, E I. Sharapov, Sharon L. Stephenson, V W. Yuan
Physics and Astronomy Faculty Publications
Parity nonconservation (PNC) has been studied in the neutron p-wave resonances of 106Pd and 108Pd in the energy range of 20 to 2000 eV. Longitudinal asymmetries in p-wave capture cross sections are measured using longitudinally polarized neutrons incident on ∼20-g metal-powder targets at LANSCE. A CsI γ-ray detector array measures capture cross section asymmetries as a function of neutron energy which is determined by the neutron time-of-flight method. A total of 21 p-wave resonances in 106Pd and 21 p-wave resonances in 108Pd were studied. One statistically significant PNC effect was observed in106Pd, and no …
Neutron Resonance Spectroscopy Of 103rh From 30 Ev To 2 Kev, D A. Smith, J D. Bowman, Bret E. Crawford, C A. Grossmann, T Haseyama, A Masaike, Y Matsuda, G E. Mitchell, S I. Penttila, N R. Roberson, S J. Seestrom, E I. Sharapov, Sharon L. Stephenson, V W. Yuan
Neutron Resonance Spectroscopy Of 103rh From 30 Ev To 2 Kev, D A. Smith, J D. Bowman, Bret E. Crawford, C A. Grossmann, T Haseyama, A Masaike, Y Matsuda, G E. Mitchell, S I. Penttila, N R. Roberson, S J. Seestrom, E I. Sharapov, Sharon L. Stephenson, V W. Yuan
Physics and Astronomy Faculty Publications
Neutron resonances in 103Rh have been measured for neutron energies from 30 to 2000 eV using the time-of-flight method and the (n,γ) reaction. The rhodium resonance spectroscopy is essential for the analysis of parity violation measurements recently performed on neutron resonances in 103Rh. Neutron scattering and radiative widths were determined, and orbital angular momentum assignments made with a Bayesian analysis. The s-wave and p-wave strength functions and average level spacings were determined.
Parity Violation In Neutron Resonances Of 103rh, D A. Smith, J D. Bowman, Bret E. Crawford, C A. Grossmann, T Haseyama, A Masaike, Y Matsuda, G E. Mitchell, S I. Penttila, N R. Roberson, S J. Seestrom, E I. Sharapov, Sharon L. Stephenson, V W. Yuan
Parity Violation In Neutron Resonances Of 103rh, D A. Smith, J D. Bowman, Bret E. Crawford, C A. Grossmann, T Haseyama, A Masaike, Y Matsuda, G E. Mitchell, S I. Penttila, N R. Roberson, S J. Seestrom, E I. Sharapov, Sharon L. Stephenson, V W. Yuan
Physics and Astronomy Faculty Publications
Parity nonconservation (PNC) was studied in p-wave neutron resonances of 103Rh in the neutron energy range 30 to 490 eV. The helicity dependence of the neutron total cross section of rhodium was determined by capture measurements with the time-of-flight method at the Manuel Lujan Neutron Scattering Center at the Los Alamos National Laboratory. A total of 32 p-wave resonances were studied and statistically significant longitudinal asymmetries were observed for resonances at En=44.5, 110.8, 321.6, and 432.9 eV. A statistical analysis treating the PNC matrix elements as random variables yields a weak spreading widthΓw=(1.42-0.59+1.21 …
Neutron Resonance Spectroscopy Of 117sn From1 Ev To 1.5 Kev, D A. Smith, J D. Bowman, Bret E. Crawford, C A. Grossmann, T Haseyama, Mikkel B. Johnson, A Masaike, Y Matsuda, G E. Mitchell, V A. Nazarenko, S I. Penttila, N R. Roberson, S J. Seestrom, E I. Sharapov, L M. Smotritsky, Sharon L. Stephenson, V W. Yuan
Neutron Resonance Spectroscopy Of 117sn From1 Ev To 1.5 Kev, D A. Smith, J D. Bowman, Bret E. Crawford, C A. Grossmann, T Haseyama, Mikkel B. Johnson, A Masaike, Y Matsuda, G E. Mitchell, V A. Nazarenko, S I. Penttila, N R. Roberson, S J. Seestrom, E I. Sharapov, L M. Smotritsky, Sharon L. Stephenson, V W. Yuan
Physics and Astronomy Faculty Publications
Parity violation has been studied recently for neutron resonances in 117Sn. The neutron resonance spectroscopy is essential for the analysis of the parity violation data. We have measured neutron resonances in 117Sn for neutron energies from 1 to 1500 eV using the time-of-flight method and the (n,γ) reaction. The sample was enriched to 87.6% 117Sn. Neutron scattering and radiative widths were determined, and orbital angular momentum assignments were made with a Bayesian analysis. The s-wave and p-wave strength functions and average level spacings were determined.
Parity Nonconservation In Neutron Resonances In 133cs, E I. Sharapov, J D. Bowman, Bret E. Crawford, P P J. Delheij, T Haseyama, J N. Knudsen, L Y. Lowie, A Masaike, Y Matsuda, G E. Mitchell, S I. Penttila, H Postma, N R. Roberson, S J. Seestrom, Sharon L. Stephenson, Y-F Yen, V W. Yuan
Parity Nonconservation In Neutron Resonances In 133cs, E I. Sharapov, J D. Bowman, Bret E. Crawford, P P J. Delheij, T Haseyama, J N. Knudsen, L Y. Lowie, A Masaike, Y Matsuda, G E. Mitchell, S I. Penttila, H Postma, N R. Roberson, S J. Seestrom, Sharon L. Stephenson, Y-F Yen, V W. Yuan
Physics and Astronomy Faculty Publications
Spatial parity nonconservation (PNC) has been studied in the compound-nuclear states of 134Cs by measuring the helicity dependence of the neutron total cross section. Transmission measurements on a thick 133Cs target were performed by the time-of-flight method at the Manuel Lujan Neutron Scattering Center with a longitudinally polarized neutron beam in the energy range from 5 to 400 eV. A total of 28 new p-wave resonances were found, their neutron widths determined, and the PNC longitudinal asymmetries of the resonance cross sections measured. The value obtained for the root-mean-square PNC element M=(0.06-0.02+0.25) meV in 133 …
Parity Violation In Neutron Resonances In 107,109ag, L Y. Lowie, J D. Bowman, J Corvi, Bret E. Crawford, P P J. Delheij, C M. Frankle, M Iinuma, J N. Knudsen, A Masaike, Y Matsuda, G E. Mitchell, S I. Penttila, H Postma, N R. Roberson, S J. Seestrom, E I. Sharapov, H M. Shimizu
Parity Violation In Neutron Resonances In 107,109ag, L Y. Lowie, J D. Bowman, J Corvi, Bret E. Crawford, P P J. Delheij, C M. Frankle, M Iinuma, J N. Knudsen, A Masaike, Y Matsuda, G E. Mitchell, S I. Penttila, H Postma, N R. Roberson, S J. Seestrom, E I. Sharapov, H M. Shimizu
Physics and Astronomy Faculty Publications
Parity nonconservation (PNC) was studied in p-wave resonances in Ag by measuring the helicity dependence of the neutron total cross section. Transmission measurements on natural Ag were performed in the energy range 32 to 422 eV with the time-of-flight method at the Manuel Lujan Neutron Scattering Center at Los Alamos National Laboratory. A total of 15 p-wave neutron resonances were studied in 107Ag and ninep-wave resonances in 109Ag. Statistically significant asymmetries were observed for eight resonances in 107Ag and for four resonances in109Ag. An analysis treating the PNC matrix elements as random variables yields a …
Search For Parity Violation In 93nb Neutron Resonances, E I. Sharapov, J D. Bowman, Bret E. Crawford, P P J. Delheij, C M. Frankle, K Fukuda, M Iinuma, J N. Knudsen, J Lokitz, L Y. Lowie, A Masaike, Y Matsuda, Y Matsuda, G E. Mitchell, S I. Penttila, H Postma, N R. Roberson, S J. Seestrom, H M. Shimizu, Sharon L. Stephenson, Y-F Yen, V W. Yuan
Search For Parity Violation In 93nb Neutron Resonances, E I. Sharapov, J D. Bowman, Bret E. Crawford, P P J. Delheij, C M. Frankle, K Fukuda, M Iinuma, J N. Knudsen, J Lokitz, L Y. Lowie, A Masaike, Y Matsuda, Y Matsuda, G E. Mitchell, S I. Penttila, H Postma, N R. Roberson, S J. Seestrom, H M. Shimizu, Sharon L. Stephenson, Y-F Yen, V W. Yuan
Physics and Astronomy Faculty Publications
A new search has been performed for parity violation in the compound nuclear states of 94Nb by measuring the helicity dependence of the neutron total cross section. Transmission measurements on a thick niobium target were performed by the time-of-flight method at the Manuel Lujan Neutron Scattering Center with a longitudinally polarized neutron beam in the energy range 32 to 1000 eV. A total of 18 p-wave resonances in 93Nb were studied with none exhibiting a statistically significant parity-violating longitudinal asymmetry. An upper limit of 1.0×10-7 eV (95% confidence level) was obtained for the weak spreading widthΓw …
Parity Nonconservation In Neutron Capture On 113cd, S J. Seestrom, J D. Bowman, Bret E. Crawford, P P J. Delheij, C M. Frankle, C R. Gould, D G. Haase, M Iinuma, J N. Knudsen, P E. Koehler, L Y. Lowie, A Masaike, Y Matsuda, G E. Mitchell, S I. Penttila, Y P. Popov, H Postma, N R. Roberson, E I. Sharapov, H M. Shimizu, D A. Smith, Sharon L. Stephenson, Y-F Yen, V W. Yuan
Parity Nonconservation In Neutron Capture On 113cd, S J. Seestrom, J D. Bowman, Bret E. Crawford, P P J. Delheij, C M. Frankle, C R. Gould, D G. Haase, M Iinuma, J N. Knudsen, P E. Koehler, L Y. Lowie, A Masaike, Y Matsuda, G E. Mitchell, S I. Penttila, Y P. Popov, H Postma, N R. Roberson, E I. Sharapov, H M. Shimizu, D A. Smith, Sharon L. Stephenson, Y-F Yen, V W. Yuan
Physics and Astronomy Faculty Publications
Parity nonconservation was studied for 23 p-wave resonances in 113Cd up to En=500eV at the LANSCE pulsed neutron source using a longitudinally polarized neutron beam and the time-of-flight method. The helicity dependence of the total neutron capture cross section was measured with an enriched 113Cd target and with a target of natural cadmium. Parity violating effects were observed for several resonances in 113Cd and 111Cd. A root-mean-square value of the parity nonconserving matrix element MJ=1=2.9-0.9+1.3meV was obtained for the spin J=1 levels in the compound nucleus 114Cd. This …
Parity Nonconservation In Neutron Resonances In 232th,, Sharon L. Stephenson, J D. Bowman, Bret E. Crawford, P P J. Delheij, C M. Frankle, M Iinuma, J N. Knudsen, L Y. Lowie, A Masaike, Y Matsuda, G E. Mitchell, S I. Penttila, H Postma, N R. Roberson, S J. Seestrom, E I. Sharapov, Y-F Yen, V W. Yuan
Parity Nonconservation In Neutron Resonances In 232th,, Sharon L. Stephenson, J D. Bowman, Bret E. Crawford, P P J. Delheij, C M. Frankle, M Iinuma, J N. Knudsen, L Y. Lowie, A Masaike, Y Matsuda, G E. Mitchell, S I. Penttila, H Postma, N R. Roberson, S J. Seestrom, E I. Sharapov, Y-F Yen, V W. Yuan
Physics and Astronomy Faculty Publications
Parity nonconservation (PNC) was measured for 24 p-wave resonances from 8 to 300 eV in 232Th by measuring the helicity dependence of the total neutron cross section for epithermal neutrons with an improved experimental system. Ten resonances show statistically significant parity violation. For these ten resonances the analyzing powers are all positive, thus confirming the previously observed sign correlation. The data are fit to the sum of two terms, a constant asymmetry and a fluctuating asymmetry. With this ansatz the root-mean-square PNC matrix element M=1.12 meV, which corresponds to a weak spreading widthΓw=4.7×10-7 eV. For the …