Showing papers by "Werner Tornow published in 1998"
TL;DR: In this paper, a high-precision determination of the 1 S 0 neutron-neutron scattering length (a nn ) using the 2 H( π −, nγ ) n reaction was reported.
77 citations
01 Jul 1998
TL;DR: In this article, the authors present the initial design of a very large liquid scintillator detector to be installed in the underground cavity where Kamiokande used to be, optimized to detect low energy anti neutrinos and perform unique measurements in the fields of neutrino physics geophysics and astrophysics.
Abstract: We present the initial design of a very large kton liquid scintillator detector to be installed in the underground cavity where Kamiokande used to be The ex periment is optimized to detect low energy anti neutrinos and it will perform unique measurements in the elds of neutrino physics geophysics and astrophysics One of the initial goals will be to perform a very long baseline oscillation experiment using a large number of nuclear reactors Such an experiment will be sensitive to neutrino masses as low as m eV attacking for the rst time with a laboratory measurement some of the possible solutions to the solar neutrino anomaly This can be considered the ultimate neutrino mass test using the oscillation technique The observation of neutrinos from the Earth supernovae atmosphere and nucleon decay will also be part of a very rich initial program while in a later stage the ob servation of solar neutrinos and other channels requiring ultra low background will become the main focus KamLAND is conceived as a scalable detector that will be able to start in a very short time to deliver results on a number of essential physics issues that only require present day technology This rst running period will also establish backgrounds and detector requirements for a second ultra low background running phase
33 citations
TL;DR: In this paper, the phase shifts of nucleon-nucleon elastic scattering were analyzed using proton-deuteron and neutron deuteron data at 3 MeV, and new sets of phase shifts were obtained that may lead to a better understanding of the long-standing elastic scattering puzzle.
Abstract: The ${}^{4}{P}_{J}$ waves in nucleon-deuteron scattering were analyzed using proton-deuteron and neutron-deuteron data at ${E}_{N}$=3 MeV New sets of nucleon-nucleon ${}^{3}{P}_{j}$ phase shifts were obtained that may lead to a better understanding of the long-standing ${A}_{y}(\ensuremath{\theta})$ puzzle in nucleon-deuteron elastic scattering However, these sets of ${}^{3}{P}_{j}$ phase shifts are quite different from the ones determined from both global phase-shift analyses of nucleon-nucleon data and nucleon-nucleon potential models
27 citations
TL;DR: In this paper, single-energy phase shift analyses of proton-deuteron elastic scattering data in the proton energy range from 3.5 to 10 MeV were performed.
14 citations
TL;DR: The current status of the three-nucleon analyzing power puzzle is reviewed in this paper, where the authors apply tight constraints on the allowed deviations between calculated predictions and accepted values for relevant nucleon nucleon observables.
7 citations
TL;DR: In this paper, the neutron-neutron and neutron-proton 1 S 0 scattering lengths were determined simultaneously from the neutron deuteron breakup reaction, in order to check on the result obtained for a nn from the two-body π − - d capture reaction, a new measurement was performed at LANL.
7 citations
21 Apr 1998-Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment
TL;DR: In this article, a beam of nearly monochromatic γ-rays was produced via intracavity Compton backscattering in the OK-4/Duke storage ring FEL.
Abstract: A beam of nearly monochromatic γ-rays was produced via intracavity Compton backscattering in the OK-4/Duke storage ring FEL. The OK-4 FEL operated in the near-UV range (345–413 nm) with electron energies of 260–550 MeV. The energy of the produced γ-rays varied from 3 to 16 MeV. In the near future we plan to increase the energy of the γ-rays to 50 MeV by increasing the electron energy and reducing FEL wavelength. Results from direct measurements of the γ-ray flux and energy resolution (using a 3 mm diameter lead collimator) (Litvinenko et al., Phys. Rev. Lett. 78 (1997) 4569) are very close to our theoretical predictions. The energy resolution of the γ-rays was ∼1%. In this paper we present a comparison of our measurements with theoretical predictions and our plans for future improvements. We discuss upgrades of our system to attain an energy resolution down to 0.1% and to increase the flux. A brief description of the experimental program utilizing the OK-4/Duke monochromatic γ-ray source is presented.
6 citations
TL;DR: In this article, the transverse polarization transfer coefficient for the reaction (H\(He) was measured for outgoing neutron energies of 1.94, 5.21, and 5.81 MeV.
Abstract: Measurements of the transverse polarization-transfer coefficient \(\) for the reaction \(\)H\(\)He are reported for outgoing neutron energies of 1.94, 5.21, and 5.81 MeV. This reaction is important both as a source of polarized neutrons for nuclear-physics experiments, and as a test of theoretical descriptions of the nuclear four-body system. Comparison is made to previous measurements, confirming that the \(\)H\(\)He reaction can be used as a polarized neutron source with the polarization known to an accuracy of approximately 5%. Comparison to R-matrix theory suggests that the sign of the \(\) phase-shift parameter is incorrect. Changing the sign of this parameter dramatically improves the agreement between theory and experiment.
5 citations
TL;DR: In this article, the transverse polarization-transfer coefficient was measured to be consistent with zero and the resonance behavior for energies corresponding to excitation of the He$ level at 21.0 MeV.
Abstract: Longitudinal polarization-transfer coefficients for the ${}^{3}\mathrm{H}(\stackrel{\ensuremath{\rightarrow}}{p},\stackrel{\ensuremath{\rightarrow}}{n}{)}^{3}\mathrm{He}$ reaction have been measured at zero degrees for proton energies of 1.3\char21{}2.8 MeV. The results show a striking resonance behavior for energies corresponding to excitation of the ${0}^{\ensuremath{-}}$ level in ${}^{4}\mathrm{He}$ at 21.0 MeV. In agreement with $R$-matrix calculations, the value approaches unity at 1.52 MeV, the peak of the resonance. Near this same energy, at 1.62 MeV, the transverse polarization-transfer coefficient was measured to be consistent with zero.
4 citations
11 Jan 1998-Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment
TL;DR: In this paper, a 0.4 mole solid 3 He target was constructed, which reached a polarization of 38% in 35 h. The target's figure of merit for neutron transmission measurement exceeds that of polarized gas targets by greater than 35.
Abstract: We have constructed a 0.4 mole solid 3 He target, cryogenically polarized at 12 mK in a field of 7 T. The 0.04 atoms/b target reached a polarization of 38% in 35 h. Such a target may be applied to any experiment which is tolerant of the large ambient magnetic field and which produces target heating of less than a microwatt. High energy neutron and photon scattering experiments meet these requirements. The target's figure of merit for neutron transmission measurement exceeds that of polarized gas targets by greater than 35. At the Triangle Universities Nuclear Laboratory we have used the target to measure the total cross section differences Δσ T and Δσ L for incident polarized neutrons of energies 2–8 MeV. The cross section difference is sensitive to the excited state structure of the n- 3 He system. The results have been compared to a recent R-matrix analysis of R = 4 scattering and reaction data, and provide support for the 4 He level scheme derived from that analysis.
2 citations
TL;DR: Litvinenko et al. as discussed by the authors argued that nuclear physicists on Duke's faculty who are short of funds are scheming to take control of the MFEL [Medical Free Electron Lasar] project and to remove Dr. Madey from his position of authority in order to facilitate their nuclear research plans.
Abstract: In the News & Comment article “Physicist sues Duke over control of lab” by Eliot Marshall (21 Nov., [p. 1393][1]), a claim in the legal brief of John Madey is summarized as follows: “nuclear physicists on Duke [University's] faculty who are short of funds are scheming to ‘take control of the MFEL [Medical Free Electron Lasar] project and to remove Dr. Madey from his position of authority in order to facilitate their nuclear research plans.’” Madey's claim has no basis in fact. It was Madey who encouraged his colleagues at the Duke Free-Electron Laser Laboratory (DFELL) and nuclear physicists from Duke's faculty to work together in order to produce high-intensity gamma-ray beams through Compton backscattering of FEL photons from high-energy electrons using the facilities at the DFELL and using detection systems provided by the Duke faculty. Madey was part of the collaboration and helped spread the news of the first successful gamma-ray production at the DFELL around the world. He was a co-author of the article in Physical Review Letters ([1][2]) which reported this result.
Madey also encouraged his colleagues at the DFELL and nuclear physicists at the Triangle Universities Nuclear Laboratory (TUNL) to write a proposal with the aim of seeking funds from the Department of Energy (DOE) to support an upgrade of the existing electron storage ring and the existing accelerator at the DFELL to make it possible to produce gamma-ray beams of higher energy than currently possible with the existing equipment. Such a proposal has recently been submitted to the DOE.
Madey, through his former Associate Director, requested that the TUNL physicists define the space needed in the planned new addition to the DFELL in order to carry out the proposed nuclear research program. Based on mutual agreement with Madey, a “gamma vault” was made part of the new building design.
The Duke University nuclear physicists conduct their research as part of TUNL's basic research program in nuclear physics. TUNL is jointly staffed by nuclear physicists from Duke University, the University of North Carolina at Chapel Hill, and North Carolina State University at Raleigh. The TUNL program has been well funded for more than 25 years by DOE and its predecessors; this funding was recently extended for 3 years at the requested level.
1. [↵][3]1. V. N. Litvinenko 2. et al.
, Phys. Rev. Lett. 78, 4569 (1997).
[OpenUrl][4][CrossRef][5][Web of Science][6]
[1]: /lookup/doi/10.1126/science.278.5342.1393a
[2]: #ref-1
[3]: #xref-ref-1-1 "View reference 1 in text"
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