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Your search keyword '"C.J. Horowitz"' showing total 11 results
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11 results on '"C.J. Horowitz"'

1. Effect of increasing neutron-excess on the fusion cross-section in 12−15C + 12C at above-barrier energies

Author

R.T. deSouza, Varinderjit Singh, S. Hudan, Z. Lin, and C.J. Horowitz

Subjects
Near-barrier fusion, Neutron-rich fusion, RIB fusion, Fusion enhancement, Physics, QC1-999
Abstract

Fusion excitation functions at energies above the fusion barrier for 12−15C + 12C are examined. From these excitation functions the average fusion cross-section, , is calculated. For this isotopic chain, the measured dependence of on neutron excess is compared with static barrier penetration models. The more rapid increase observed for the experimental cross-sections above the geometric increase predicted by the static models suggests that the stronger dependence on neutron-excess measured may be attributable to dynamics. Calculations with a time-dependent Hartree-Fock model also fail to describe the observed trend suggesting that for neutron-rich nuclei, neutron dynamics may play a larger role than is presently accounted for.

Published
2021
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2. Weak radius of the proton

Author

C.J. Horowitz

Subjects
Physics, QC1-999
Abstract

The weak charge of the proton determines its coupling to the Z0 boson. The distribution of weak charge is found to be dramatically different from the distribution of electric charge. The proton's weak radius RW=1.545±0.017 fm is 80% larger than its charge radius Rch≈0.84 fm because of a very large pion cloud contribution. This large weak radius can be measured with parity violating electron scattering and may provide insight into the structure of the proton, various radiative corrections, and possible strange quark contributions.

Published
2019
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3. Search for compact dark matter objects in the solar system with LIGO data

Author

C.J. Horowitz, M.A. Papa, and S. Reddy

Subjects
Physics, QC1-999
Abstract

Dark matter could be composed of compact dark objects (CDOs). A close binary of CDOs orbiting in the interior of solar system bodies can be a loud source of gravitational waves (GWs) for the LIGO and VIRGO detectors. We perform the first search ever for this type of signal and rule out close binaries, with separations of order 300 m, orbiting near the center of the Sun with GW frequencies (twice the orbital frequency) between 50 and 550 Hz and CDO masses above ≈10−9M⊙. This mass limit is eight orders of magnitude lower than the mass probed in a LIGO search at extra galactic distances.

Published
2020
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4. Fusion enhancement at near and sub-barrier energies in 19O + 12C

Author

Varinderjit Singh, J. Vadas, T.K. Steinbach, B.B. Wiggins, S. Hudan, R.T. deSouza, Zidu Lin, C.J. Horowitz, L.T. Baby, S.A. Kuvin, Vandana Tripathi, I. Wiedenhöver, and A.S. Umar

Subjects
Near-barrier fusion, Neutron-rich fusion, RIB fusion, Fusion enhancement, Physics, QC1-999
Abstract

Measuring the fusion excitation function for an isotopic chain of projectile nuclei provides a stringent test of a microscopic description of fusion. We report the first measurement of the fusion excitation function at near-barrier energies for the 19O + 12C system. The measured excitation function is compared with the fusion excitation function of 18O + 12C. A significant enhancement in the fusion probability of 19O ions with a 12C target as compared to 18O ions is observed. The experimental cross-sections observed at near-barrier energies are compared with a state-of-the-art microscopic model.

Published
2017
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6. Constraining URCA cooling of neutron stars from the neutron radius of208Pb

Author

C.J. Horowitz and J. Piekarewicz

Subjects
Physics, Nuclear and High Energy Physics, Astrophysics::High Energy Astrophysical Phenomena, Nuclear Theory, Extrapolation, Nuclear physics, Neutron star, Neutron cross section, r-process, Neutron, Nuclear Experiment, s-process, Urca process, Electron scattering
Abstract

Recent observations by the Chandra observatory suggest that some neutron stars may cool rapidly, perhaps by the direct URCA process which requires a high proton fraction. The proton fraction is determined by the nuclear symmetry energy whose density dependence may be constrained by measuring the neutron radius of a heavy nucleus, such as 208Pb. Such a measurement is necessary for a reliable extrapolation of the proton fraction to the higher densities present in the neutron star. A large neutron radius in 208Pb implies a stiff symmetry energy that grows rapidly with density, thereby favoring a high proton fraction and allowing direct URCA cooling. Predictions for the neutron radius in 208Pb are correlated to the proton fraction in dense matter by using a variety of relativistic effective field-theory models. Models that predict a neutron (Rn) minus proton (Rp) root-mean-square radius in 208Pb to be Rn-Rp 0.25 fm, the direct URCA process is allowed (by all models) to cool down a 1.4 solar-mass neutron star. The Parity Radius Experiment at Jefferson Laboratory aims to measure the neutron radius in 208Pb accurately and model independently via parity-violating electron scattering. Such a measurement would greatly enhance our ability to either confirm or dismiss the direct URCA cooling of neutron stars.

Published
2002
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9. Theoretical studies in medium-energy nuclear and hadronic physics

Author

B.D. Serot, Tetsuo Matsui, M.H. Macfarlane, and C.J. Horowitz

Subjects
Physics, Quark, Nuclear reaction, Particle physics, Astrophysics::High Energy Astrophysical Phenomena, Nuclear Theory, Nuclear structure, Nuclear matter, Quarkonium, Nuclear physics, Strange matter, Pion, Neutrino, Nuclear Experiment
Abstract

In the period covered by this report (April 1, 1991 to March 31, 1992), work focused on six main areas: (1) Relativistic Theories of Nuclear Structure and Saturation, (2) Relativistic Descriptions of Proton-Nucleus and Electron-Nucleus Scattering, (3) Nonrelativistic Theory of Nucleon-Nucleus Reactions, (4) Relativistic Many-Body Theory at Finite Temperature and Density, (5) Neutrino Interactions in Dense Matter, (6) Quark Models of Nuclear and Quark Matter.

Published
1991
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10. Theoretical studies in medium-energy nuclear and hadronic physics. Annual technical progress report, April 1, 1991--March 31, 1992

Author

Tetsuo Matsui, B.D. Serot, C.J. Horowitz, and M.H. Macfarlane

Subjects
Quark, Physics, Particle physics, Astrophysics::High Energy Astrophysical Phenomena, Nuclear Theory, Hadron, Quark model, Nuclear structure, Nuclear matter, Nuclear physics, Strange matter, Pion, Neutrino, Nuclear Experiment
Abstract

In the period covered by this report (April 1, 1991 to March 31, 1992), work focused on six main areas: (1) Relativistic Theories of Nuclear Structure and Saturation, (2) Relativistic Descriptions of Proton-Nucleus and Electron-Nucleus Scattering, (3) Nonrelativistic Theory of Nucleon-Nucleus Reactions, (4) Relativistic Many-Body Theory at Finite Temperature and Density, (5) Neutrino Interactions in Dense Matter, (6) Quark Models of Nuclear and Quark Matter.

Published
1991
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11. Spin observables for 208Pb(→p, →p) elastic scattering at 290 MeV

Author

K.H. Hicks, C. A. Miller, O. Häusser, D.K. McDaniels, C.J. Horowitz, K. P. Jackson, L.W. Swenson, J. Lisantti, R. Sawafta, Robert Henderson, A. Celler, R. L. Helmer, D. J. Horen, R. Abegg, C. Gunther, and C.W. Glober

Subjects
Elastic scattering, Physics, Nuclear and High Energy Physics, Spectrometer, Nuclear Theory, Momentum transfer, Polarimeter, Observable, Polarization (waves), Nuclear physics, symbols.namesake, Pauli exclusion principle, Amplitude, symbols, Atomic physics, Nuclear Experiment
Abstract

A newly constructed focal-plane polarimeter for the medium resolution spectrometer at TRIUMF has been used to measure polarizations and polarization transfer coefficients for protons elastically scattered from 208Pb at 290 MeV. These results combined with existing cross section data at 300 MeV completely determine the elastic scattering amplitudes for momentum transfers q

Published
1987
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