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J. W. Watson,
Q.‐Q. Du,
B. D. Anderson,
A. R. Baldwin,
C. C. Foster,
L. A. C. Garcia,
X.‐D. Hu,
R. Kurmanov,
D. L. Lamm,
R. Madey, P. J. Pella,
E. J. Stephenson,
Y. Wang,
B. Wetmore,
W.‐M. Zhang
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ABSTRACT: We designed, tested and calibrated a medium‐energy neutron polarimeter of a new design, which we call the ‘‘2π’’ polarimeter because of its symmetric coverage of all 2π of azimuth for double‐scattered neutrons. During calibration tests at the IUCF we observed an over all neutron time‐of‐flight resolution of 360 ps. The measured analyzing power is typically 39% for neutrons of both 130 and 165 MeV for optimum software cuts. The efficiency is typically 0.3%. © 1995 American Institute of Physics.
AIP Conference Proceedings. 08/1995; 343(1):203-208.
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R. Madey,
T. Eden,
W. M. Zhang,
B. D. Anderson,
A. R. Baldwin,
D. Keane,
D. M. Manley,
J. W. Watson,
S. Kowalski,
W. Bertozzi, [......],
J. M. Cameron,
B. Ni,
M. Spraker,
J. Mougey,
P. Ulmer,
R. Whitney,
B. S. Flanders, P. J. Pella,
C. E. Hyde‐Wright,
W. Jiang
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ABSTRACT: The Bates E85‐05 Collaboration measured the polarization of the neutron in the d(e↘,en↘)p reaction in the quasifree region with the objective of extracting the electric form factor of the neutron. Electron‐neutron coincidence spectra were obtained during 567 μA‐hours of integrated beam. We succeeded in operating a Møller scattering polarimeter in the coincidence mode with a low‐duty factor accelerator in order to measure the polarization of the electron beam.
AIP Conference Proceedings. 12/1991; 243(1):954-959.
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ABSTRACT: Polarimeters for medium-energy neutrons are described which are
based on the fact that scattering of polarized neutrons from unpolarized
hydrogen nuclei exhibits a left-right (or an up-down) asymmetry.
Configurations are described for neutron polarimeters that use the
analyzing power of neutron-proton scattering from the hydrogen in an
organic scintillator material. The scattering angle θ an the
azimuthal (out-of-plane) angle φ for the neutron-proton scattering
event are determined from the position of the interaction in each of the
two detectors involved in a given event. Consideration is given to
V-configuration polarimeters, and axial-configuration polarimeter for
use with a solid-angle-limiting aperture of a neutron spin-rotation
magnet between the target and the polarimeter, and polarimeters
configured with parallel planes of scintillator material
IEEE Transactions on Nuclear Science 03/1989; · 1.45 Impact Factor
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T. Eden,
R. Madey,
W.-M. Zhang,
B.D. Anderson,
A.R. Baldwin,
J.M. Cameron,
J.M. Finn,
C.C. Foster,
J.J. Kelly,
S. Kowalski,
R. Lourie,
P. Markowitz,
B. Ni, P.J. Pella,
J. Schambach,
M. Spraker,
E. Steinfelds,
E.J. Stephenson,
J.W. Watson
[show abstract]
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ABSTRACT: We measured the analyzing power and the efficiency of a neutron polarimeter that was designed and constructed to measure the neutron electric form factorGEn. The measurement was carried out at the Indiana University Cyclotron Facility (IUCF) with the reaction at a proton beamenergy of 138.4 MeV. The analyzing power, 〈Ay〉, averaged over the acceptance of the polarimeter is typically 0.44±0.02−0.03+0.04 at a neutron energy of 135 MeV. With a lead-steel wall, consisting of 4 in. of lead sandwiched between two -in. steel plates, ahead of the polarimeter, the average analyzing power is the same within statistics, namely, 〈Ay〉 = 0.43 ± 0.02−0.03+0.04. The large systematic uncertainty quoted here is dominated by an uncertainty from the inability at the time of the experiment of measuring the longitudinal polarization component of the sideways polarized protons; this systematic uncertainty can be reduced significantly to 0.02 in any future calibration at the IUCF. In each case, the efficiency of the polarimeter is about 0.26% for 135 MeV neutrons at a pulse-height threshold of 4 MeV equivalent electron energy (MeVee) on the front detectors and 10 MeVee on the rear detectors. This analysis reveals a small analyzing power from the carbon in the front-analyzer detectors.
Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment.
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ABSTRACT: We measured the spin observables Ay, P, and SNN′ for the 208Pb(p,n)208Bi reaction at 135 MeV at laboratory angles of 0°, 3°, 6°, and 9°. The overall energy resolution was about 1 MeV. Data for SNN′ are compared with distorted-wave impulse-approximation calculations that use random-phase approximation wave functions. Comparisons are also made for the 48Ca(p,n)48Sc reaction. The agreement between these calculations and the data is generally good, after adjustment of the nucleon-nucleon interaction in the random-phase approximation calculations to place the 0+ isobaric-analog states at the correct excitation energies. A single adjustment of the nucleon-nucleon force works for both target nuclei.
Phys. Rev. C. 56(1).
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J. W. Watson,
Q.-Q. Du,
B D Anderson,
A.R. Baldwin,
L. A. C. Garcia,
X.-D. Hu,
D.L. Lamm,
R. Madey,
Y Wang,
B. Wetmore,
W M Zhang,
C.C. Foster,
E.J. Stephenson,
R. Kurmanov, P.J. Pella
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T. Eden,
R. Madey,
W M Zhang,
B D Anderson,
A.R. Baldwin,
J. Schambach,
E. Steinfelds,
J. W. Watson,
S. Kowalski,
J.J. Kelly,
J.M. Finn,
P. Markowitz,
R. Lourie, P.J. Pella,
J. Cameron,
C.C. Foster,
B. Ni,
M Spraker,
E.J. Stephenson
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ABSTRACT: The spin observable DNN′(θ) was measured for () at 135 MeV on 16O, 40Ca, 48Ca, and 208Pb. Data for 16O and 40Ca are compared with distorted-wave impulse approximation (DWIA) calculations with Tamm-Dancoff (TDA) wave functions; the DNN′ data generally agree with the Jπ distribution (O−, 1−, 2−) predicted for the “spin-dipole” resonance.
Nuclear Physics A.
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ABSTRACT: We measured the analyzing power Ay and the triple differential cross section d3σ/dΩpdΩndEp for the 2H(p→,pn)1H reaction at 200 MeV. Coplanar coincidence data were taken for all combinations of neutron angles θn=35°, 45°, or 55° with proton angles θp=35°, 45°, or 52°. Protons were detected with a ΔE-E telescope with a 1000-μm silicon surface barrier ΔE detector and a plastic scintillator E detector. Neutrons were detected with large-volume plastic scintillators at flight paths of 17.5 or 18 m. The overall neutron separation-energy resolution was about 3 MeV. Data are compared with plane-wave impulse-approximation calculations with a Hulthén deuteron wave function and p-n cross sections and analyzing powers obtained from N-N phase shifts. The agreement between these calculations and the data is generally good for the cross sections. The agreement for the analyzing powers is good near the point of zero recoil momentum. Our results suggest that the deuteron is a good ‘‘neutron target’’ for recoil momenta <100 MeV/c.
Phys. Rev. C. 52(5).
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R. Madey,
J.W. Watson,
M. Ahmad,
B.D. Anderson,
A.R. Baldwin,
A.L. Casson,
W. Casson,
R.A. Cecil,
A. Fazely,
J.M. Knudson,
C. Lebo,
W. Pairsuwan, P.J. Pella,
J.C. Varga,
T.R. Witten
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ABSTRACT: Design criteria and performance characteristics are described for large-volume (13.1 1 to 118 1) mean-timed plastic-scintillator detectors for neutrons from ≈2 MeV to 2 GeV. Detectors were constructed in six sizes (all 0.102 m thick) from 0.126 m × 1.016 m × 0.102 m to 0.762 m × 1.524 m × 0.102 m. Overall energy resolutions of 230 keV for 80 MeV neutrons, 320 keV for 133 MeV neutrons, and 440 keV for 157 MeV neutrons were achieved in time-of-flight experiments with flight paths of 76, 68, and 91 m, respectively. The detectors have pulse-height responses uniform to ±5% except close to the ends, position resolutions less than 5 cm, and intrinsic time dispersions less than 400 ps. Typical neutron detection efficiencies are 20% for 20 MeV neutrons at a pulse-height threshold of 2 MeV equivalent-electron energy (MeV ee) and 3.5% for 200 MeV neutrons at a pulse-height threshold of 50 MeV ee.
Nuclear Instruments and Methods in Physics Research.
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ABSTRACT: A polarimeter for medium-energy neutrons is described. This polarimeter uses the analyzing power of n–p scattering which is typically +0.50 for laboratory neutron scattering angles near 20° in the energy range from 50 MeV to 1 GeV. Hydrocarbon organic scintillators are employed as “active” scatterers. Calibration data for the analyzing power and the efficiency of the polarimeter are presented.
Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment.
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ABSTRACT: Nous avons mesuré les spectres d'énergies de séparation et les sections efficaces pour les réactions 2H, 9Be, 16O, 28Si, 58Ni, et 90Zr (p,pn) à 150 MeV. On essaie d'identifier les énergies des états "trous profonds" de neutrons. We measured separation-energy spectra and cross sections for the reaction on 2H, 9Be, 16O, 28Si, 58Ni, and 90Zr at 150 MeV. Energies of neutron deep-hole states are tentatively identified.
http://dx.doi.org/10.1051/jphyscol:1984409.
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ABSTRACT: The polarization (P) and the analyzing power (A) were measured for the 48Ca(p,n)48Sc reaction at 135 MeV. Of special interest is the difference (P-A) in these two quantities for the transitions to the two 1+ states at 2.52 and 16.8 MeV. Because of the difference in the predominant one-particle–one-hole configurations for these two states, viz., (f7/2,f7/2-1) and (f5/2,f7/2-1), respectively, qualitative differences in P-A are predicted based on nonlocal exchange contributions. The experimental results agree qualitatively with these predicted differences, but there are significant quantitative differences indicating that other effects contribute as well.
Phys. Rev. C. 45(6).
