37 research outputs found
New analysis of the common nuclear dependence of the EMC effect and short-range correlations
The strong repulsive core of the nucleon-nucleon (NN) interaction at short
distances prevents nucleons from becoming close to each other. This gives rise
to high-momentum nucleons in the nucleus that cannot be explained in the
context of the mean field and are commonly called short-range correlations
(SRCs). They are responsible for the strength seen in momentum distribution
tails seen in all nuclei, and we can obtain a relative measure of SRCs via
cross section ratios to light nuclei. Recent inclusive scattering data from
Jefferson Lab have allowed a precise determination of the A-dependence of SRCs
in nuclei and suggests that, like the EMC effect, it is especially sensitive to
the nuclear local density. These new results, as well as a new analysis of the
relationship between SRCs and the EMC effect, will be presented and discussed.Comment: CIPANP Proceeding
Searching for three-nucleon short-range correlations
Electron scattering measurements from high-momentum nucleons in nuclei at
SLAC and Jefferson Lab (JLab) have shown that these nucleons are generally
associated with two-nucleon short-range correlations (2N-SRCs). These SRCs are
formed when two nucleons in the nucleus interact at short distance via the
strong tensor attraction or repulsive core of the NN potential. A series of
measurements at JLab have mapped out the A dependence and isospin dependence of
2N-SRCs, and have begun to map out their momentum structure. However, we do not
yet know if 3N-SRCs, similar high-momentum configurations of three nucleons,
play an important role in nuclei. We summarize here previous attempts to
isolate 3N-SRCs, go over the limitations of these previous attempts, and
discuss the present and near-term prospects for searching for 3N-SRCs, mapping
out their A dependence in nuclei, and constraining their isospin and momentum
structure
Fundamental Neutron Physics at Spallation Sources
Low-energy neutrons have been a useful probe in fundamental physics studies for more than 70 years. With advances in accelerator technology, many new sources are spallation based. These new, high-flux facilities are becoming the sites for many next-generation fundamental neutron physics experiments. In this review, we present an overview of the sources and the current and upcoming fundamental neutron physics programs
Deficiency in Perlecan/HSPG2 During Bone Development Enhances Osteogenesis and Decreases Quality of Adult Bone in Mice
Perlecan/HSPG2 (Pln) is a large heparan sulfate proteoglycan abundant in the extracellular matrix of cartilage and the lacunocanalicular space of adult bones. Although Pln function during cartilage development is critical, evidenced by deficiency disorders including Schwartz–Jampel Syndrome and dyssegmental dysplasia Silverman-Handmaker type, little is known about its function in development of bone shape and quality. The purpose of this study was to understand the contribution of Pln to bone geometric and mechanical properties. We used hypomorph mutant mice that secrete negligible amount of Pln into skeletal tissues and analyzed their adult bone properties using micro-computed tomography and three-point-bending tests. Bone shortening and widening in Pln mutants was observed and could be attributed to loss of growth plate organization and accelerated osteogenesis that was reflected by elevated cortical thickness at older ages. This effect was more pronounced in Pln mutant females, indicating a sex-specific effect of Pln deficiency on bone geometry. Additionally, mutant females, and to a lesser extent mutant males, increased their elastic modulus and bone mineral densities to counteract changes in bone shape, but at the expense of increased brittleness. In summary, Pln deficiency alters cartilage matrix patterning and, as we now show, coordinately influences bone formation and calcification
Precision pulse shape simulation for proton detection at the Nab experiment
The Nab experiment at Oak Ridge National Laboratory, USA, aims to measure the
beta-antineutrino angular correlation following neutron decay to an
anticipated precision of approximately 0.1\%. The proton momentum is
reconstructed through proton time-of-flight measurements, and potential
systematic biases in the timing reconstruction due to detector effects must be
controlled at the nanosecond level. We present a thorough and detailed
semiconductor and quasiparticle transport simulation effort to provide precise
pulse shapes, and report on relevant systematic effects and potential
measurement schemes
Electric dipole moments and the search for new physics
Static electric dipole moments of nondegenerate systems probe mass scales for
physics beyond the Standard Model well beyond those reached directly at high
energy colliders. Discrimination between different physics models, however,
requires complementary searches in atomic-molecular-and-optical, nuclear and
particle physics. In this report, we discuss the current status and prospects
in the near future for a compelling suite of such experiments, along with
developments needed in the encompassing theoretical framework.Comment: Contribution to Snowmass 2021; updated with community edits and
endorsement