Simulator investigation of arrow-wing low-speed handling qualities

Low speed handling qualities of arrow wings were investigated with a piloted simulator. Existing aerodynamic data were used from NASA SCAT 15F tunnel tests augmented with Lockheed low speed wind tunnel test data. Two arrow wing planforms were chosen for the simulation effort a Mach 2.0 design and a Mach 2.7 design. These designs are in the SCAT 15F Mach 2.7 design family, having the same beta AR and beta cot lambda. Piloted simulation results indicate that both the Mach 2.0 and Mach 2.7 planforms have satisfactory longitudinal flying qualities. However, in the control of bank angle the Mach 2.0 planform demonstrates satisfactory handling qualities while the Mach 2.7 planform is unacceptable. This situation applies for crosswind landings at FAA limits and for lineup in heavy turbulence. The low speed superiority of the Mach 2 planform with its lower sweep and higher aspect ratio is also shown by its ability to approach at least 8 m/s slower than the Mach 2.7 planform without degradation in handling qualities

Transonic aerodynamic damping and oscillatory stability in yaw and pitch for a model of a variable-sweep supersonic transport airplane

Transonic aerodynamic stability and damping in yaw and pitch for variable sweep supersonic transport mode

First Measurements of Spin-Dependent Double-Differential Cross Sections and the Gerasimov-Drell-Hearn Integrand from (3)(H)over-right-arrowe((gamma)over-right-arrow, n)pp at Incident Photon Energies of 12.8 and 14.7 MeV

The first measurement of the three-body photodisintegration of longitudinally polarized He-3 with a circularly polarized gamma-ray beam was carried out at the High Intensity gamma-ray Source facility located at Triangle Universities Nuclear Laboratory. The spin-dependent double-differential cross sections and the contributions from the three-body photodisintegration to the He-3 Gerasimov-Drell-Hearn integrand are presented and compared with state-of-the-art three-body calculations at the incident photon energies of 12.8 and 14.7 MeV. The data reveal the importance of including the Coulomb interaction between protons in three-body calculations

Probing the Repulsive Core of the Nucleon-Nucleon Interaction via the He-4(e,e\u27pN) Triple-Coincidence Reaction

We studied simultaneously the He-4(e,e\u27p), He-4(e,e\u27pp), and He-4(e,e\u27pn) reactions at Q(2) 2(GeV/c)(2) and x(B) \u3e 1, for an (e,e\u27p) missing-momentum range of 400 to 830 MeV/c. The knocked-out proton was detected in coincidence with a proton or neutron recoiling almost back to back to the missing momentum, leaving the residual A = 2 system at low excitation energy. These data were used to identify two-nucleon short-range correlated pairs and to deduce their isospin structure as a function of missing momentum, in a region where the nucleon-nucleon (NN) force is expected to change from predominantly tensor to repulsive. The abundance of neutron- proton pairs is reduced as the nucleon momentum increases beyond similar to 500 MeV/c. The extracted fraction of proton-proton pairs is small and almost independent of the missing momentum. Our data are compared with calculations of two-nucleon momentum distributions in He-4 and discussed in the context of probing the elusive repulsive component of the NN force

Moments of the neutron g(2) structure function at intermediate Q(2)

We present new experimental results for the He-3 spin structure function g(2) in the resonance region atQ 2 values between 1.2 and 3.0 (GeV/c)(2). Spin dependent moments of the neutron were extracted. Our main result, the inelastic contribution to the neutron d(2) matrix element, was found to be small at \u3c Q(2)\u3e = 2.4 (GeV/c)(2) and in agreement with the lattice QCD calculation. The Burkhardt-Cottingham sum rule for He-3 and the neutron was tested with the measured data and using the Wandzura-Wilczek relation for the low x unmeasured region

Precision measurements of A(1)(n) in the deep inelastic regime

We have performed precision measurements of the double-spin virtual-photon asymmetry A(1) on the neutron in the deep inelastic scattering regime, using an open-geometry, large-acceptance spectrometer and a longitudinally and transversely polarized He-3 target. Our data cover a wide kinematic range 0.277 \u3c = x \u3c = 0.548 at an average Q(2) value of 3.078(GeV/c)(2), doubling the available high-precision neutron data in this xrange. We have combined our results with world data on proton targets to make a leading-order extraction of the ratio of polarized-to-unpolarized parton distribution functions for up quarks and for down quarks in the same kinematic range. Our data are consistent with a previous observation of an A(1)(n) zero crossing near x = 0.5. We find no evidence of a transition to a positive slope in (Delta d + Delta(d) over bar)/(d + (d) over bar) up to x = 0.548. (C) 2015 The Authors. Published by Elsevier B.V

Measurement of Double-Polarization Asymmetries in the Quasielastic (3)(He)over-right-arrow((e)over-right-arrow,e \u27 d) Process

We present a precise measurement of double-polarization asymmetries in the (3)(He) over right arrow((e) over right arrow ,e\u27d) reaction. This particular process is a uniquely sensitive probe of hadron dynamics in He-3 and the structure of the underlying electromagnetic currents. The measurements have been performed in and around quasielastic kinematics at Q(2) = 0.25(GeV/c)(2) for missing momenta up to 270 MeV/c. The asymmetries are in fair agreement with the state-of-the-art calculations in terms of their functional dependencies on p(m) and omega, but are systematically offset. Beyond the region of the quasielastic peak, the discrepancies become even more pronounced. Thus, our measurements have been able to reveal deficiencies in the most sophisticated calculations of the three-body nuclear system, and indicate that further refinement in the treatment of their two-and/or three-body dynamics is required

Precision Measurement of the Neutron Twist-3 Matrix Element d(2)(n): Probing Color Forces

Double-spin asymmetries and absolute cross sections were measured at large Bjorken x (0.25 of 3.21 and 4.32 GeV2/c(2), with an absolute precision of about 10(-5). Our results are found to be in agreement with lattice QCD calculations and resolve the disagreement found with previous data at \u3c Q(2)\u3e = 5 GeV2/c(2). Combining d(2)(n) and a newly extracted twist-4 matrix element f(2)(n), the average neutron color electric and magnetic forces were extracted and found to be of opposite sign and about 30 MeV/fm in magnitude

Beam-Target Double-Spin Asymmetry A(LT) in Charged Pion Production from Deep Inelastic Scattering on a Transversely Polarized He-3 Target at 1.4 \u3c Q(2) \u3c 2.7 GeV2

We report the first measurement of the double-spin asymmetry A(LT) for charged pion electroproduction in semi-inclusive deep-inelastic electron scattering on a transversely polarized He-3 target. The kinematics focused on the valence quark region, 0.16 \u3c x \u3c 0.35 with 1.4 \u3c Q(2) \u3c 2.7 GeV2. The corresponding neutron A(LT) asymmetries were extracted from the measured He-3 asymmetries and proton over He-3 cross section ratios using the effective polarization approximation. These new data probe the transverse momentum dependent parton distribution function g(1T)(q) and therefore provide access to quark spin-orbit correlations. Our results indicate a positive azimuthal asymmetry for pi(-) production on He-3 and the neutron, while our pi(+) asymmetries are consistent with zero

Measurements of d(2)(n) and A(1)(n) : Probing the neutron spin structure

We report on the results of the E06-014 experiment performed at Jefferson Lab in Hall A, where a precision measurement of the twist-3 matrix element d(2) of the neutron (d(2)(n)) was conducted. The quantity d(2)(n) represents the average color Lorentz force a struck quark experiences in a deep inelastic electron scattering event off a neutron due to its interaction with the hadronizing remnants. This color force was determined from a linear combination of the third moments of the He-3 spin structure functions, g(1) and g(2), after nuclear corrections had been applied to these moments. The structure functions were obtained from a measurement of the unpolarized cross section and of double-spin asymmetries in the scattering of a longitudinally polarized electron beam from a transversely and a longitudinally polarized He-3 target. The measurement kinematics included two average Q(2) bins of 3.2 GeV2 and 4.3 GeV2, and Bjorken-x 0.25 = 3.2 GeV2, and even smaller for \u3c Q(2)\u3e = 4.3 GeV2, consistent with the results of a lattice QCD calculation. The twist-4 matrix element f(2)(n) was extracted by combining our measured d(2)(n) with the world data on the first moment in x of g(1)(n), Gamma(n)(1). We found f(2)(n) to be roughly an order of magnitude larger than d(2)(n). Utilizing the extracted d(2)(n) and f(2)(n) data, we separated the Lorentz color force into its electric and magnetic components, F-E(y,n) and F-B(y,n), and found them to be equal and opposite in magnitude, in agreement with the predictions from an instanton model but not with those from QCD sum rules. Furthermore, using the measured double-spin asymmetries, we have extracted the virtual photon-nucleon asymmetry on the neutron A(1)(n), the structure function ratio g(1)(n)/F-1(n), and the quark ratios (Delta u + Delta(u) over bar)/(u + (u) over bar) and (Delta d + Delta(d) over bar)/(d + (d) over bar). These results were found to be consistent with deep-inelastic scattering world data and with the prediction of the constituent quark model but at odds with the perturbative quantum chromodynamics predictions at large x