References for Pb208 Parity Violating Experiment (P-ReX)
C. J.. Horowitz, Indiana University
Uses parity violating electorn scattering to measure the neutron radius
Pb208 at Hall A in Jeferson Lab.
Jeferson Laboratory Experiment E00-003, R. Michaels, P. Souder, G.
Long paper giving analysys of experiment:
Violating Measurements of Neutron Densities
C. J. Horowitz, S. J. Pollock, P. A. Souder, R. Michaels, Phys.Rev. C63
Calculation of Coulomb distortions:
Violating Elastic Electron Scattering and Coulomb Distortions
C. J. Horowitz (Indiana), Phys.Rev. C57 (1998) 3430-3436.
Original sugestion of measuring neutron densities with parity violation:
T. M. Donnelly, J. Dubach and Ingo Sick, Nuc. Phys. A503 (1989) 509.
The neutron radius measurement determines the density dependence of the
The symmetry energy determines how the energy of nuclear matter rises
one goes away from
equal numbers of neutrons and protons. A symmetry energy that
rapidly with density leads
to a large pressure for the neutrons in the neutron rich skin of Pb208
this gives a large
neutron radius. Relativistic mean filed models tend to predict a
rapid density dependence
for the symetery energy and a larger neutron radius than
The equation of state of neutron rich matter
The equation of state, the pressure as a function of the density, is a
Measureing the neutron radius in Pb determines the pressure of neutron
normal density. Alternatively, assuming one nonrel. microscopic
presure of neutron matter yields R_n-R_p=0.16 +/- 0.02 fm for the
proton and neutron radii in Pb. [Note, unknown three-body forces
B. A. Brown, Phys. Rev. Lett., 85 (2000) 5296.
This has many implications for neutron stars. For example,
Star Structure and the Neutron Radius of 208Pb
C. J. Horowitz, J. Piekarewicz, Phys.Rev.Lett. 86 (2001) 5647.
A short popular article about determining properties of neutron stars
the Pb measurement is
Newscientist 2294 (2001) 11.
radii of Lead and neutron stars
C. J. Horowitz, J. Piekarewicz, Phys.Rev. C64 (2001) 062802.
URCA Neutron Star Cooling and the symetry energy of Dense Matter
A large symmetry energy favors more symmetric neutron rich matter with
larger fraction of protons.
If the proton fraction is high enough than the following so called URCA
can rapidly cool neutron
stars. Note, neutron stars cool by neutrino emision because
of their very small surface areas.
n-> p + e + anti\nu
p+e -> n + \nu
Where the \nu anti\nu pair carry off energy. Relativistic models
a larger neutron radius in Pb tend to allow
URCA cooling while nonrelativistic models with a small Pb radius
to not allow URCA cooling.
Constraining URCA cooling of neutron stars from the neutron radius of
C. J. Horowitz, J. Piekarewicz, Phys.Rev.
C66 (2002) 055803
Recently the neutron star in 3C 58 was observed by the Chandra X-ray
to be cold. This is the remanent from
a Supernova observed in 1181. Hence it is only 800 years old and
have cooled quickly. Note, this was described
in a April 11 New York Times article.
Constraints on Neutron Star Cooling from Chandra Observations
Patrick Slane, David J. Helfand, Stephen S. Murray, accepted by ApJ
Relationship between density dependence of symmetry energy and
from the giant monoploe resonance.
journey from the giant-monopole resonance to the
nuclear-matter incompressibility, J. Piekarewicz to be published.
Some nuclear structure calculations of neutron densities
Radii in Mean-Field Models
R. J. Furnstahl.
density distributions for atomic parity nonconservation experiments
D. Vretenar, G.A. Lalazissis, P. Ring, Phys.Rev. C62 (2000) 045502.
violating elastic electron scattering and neutron density
distributions in the Relativistic Hartree-Bogoliubov model
D. Vretenar, P. Finelli, A. Ventura, G.A. Lalazissis, P. Ring,
C61 (2000) 064307.
Selected proton scattering determinations of neutron densities
nucl-th/0111020, Discerning the neutron density distribution of 208Pb
nucleon elastic scattering
S. Karataglidis, K. Amos, B. A. Brown, P. K. Deb, Phys.Rev. C65
Note, this paper finds more sensitivity to the surface thicknes than to
If one can "calibrate" the uncertian strong interaction reaction
for proton scattering with a parity
violating radius measurement one can use proton scattering to measure
neutron density in
nucl-th/9811051, Proton Elastic Scattering and Neutron Distribution of
K.Kaki, S.Hirenzaki, Int.J.Mod.Phys. E8 (1999) 167-178