19,483 research outputs found
New data strengthen the connection between Short Range Correlations and the EMC effect
Recently published measurements of the two nucleon short range correlation
(-SRC) scaling factors, , strengthen the previously observed
correlation between the magnitude of the EMC effect measured in electron deep
inelastic scattering at and the SRC scaling factor
measured at . The new results have improved precision and include
previously unmeasured nuclei. The measurements of for Be and
Au agree with published predictions based on the EMC-SRC correlation.
This paper examines the effects of the new data and of different corrections to
the data on the slope and quality of the EMC-SRC correlation, the size of the
extracted deuteron IMC effect, and the free neutron structure function. The
results show that the linear EMC-SRC correlation is robust and that the slope
of the correlation is insensitive to most combinations of corrections examined
in this work. This strengthens the interpretation that both -SRC and the
EMC effect are related to high momentum nucleons in the nucleus.Comment: 4 pages, 1 figure. v3: minor changes to respond to PRC referee
comments. v2: Minor errors in tabulated data corrected. No change to text or
conclusion
Cesium standard for satellite application
A Cesium frequency standard that was developed for satellite applications is discussed. It weighs 23 lbs. and uses 23.5 watts of power, achieves a stability of 1 x ten to the minus 13th power/100,000 seconds, and is radiation hardened. To achieve the weight and reliability requirements, both thick and thin film hybrid circuits were utilized. A crystal oscillator is used to improve short-term stability and performance on a moving platform
Heat-transfer and pressure measurements on a simulated elevon deflected 30 deg near flight conditions at Mach 7
Heat transfer rates and pressures were obtained on an elevon plate (deflected 30 deg) and a flat plate upstream of the elevon in an 8 foot high-temperature structures tunnel. The flight Reynolds number and flight total enthalpy for altitudes of 26.8 km and 28.7 km at Mach seven were duplicated. The heat transfer and pressure data were used to establish heating and pressure loads. The measured heating was compared with several theoretical predictions, and the closest agreement obtained with a Schultz-Grunow reference enthalpy method of calculation
Hammer events, neutrino energies, and nucleon-nucleon correlations
Neutrino oscillation measurements depend on a difference between the rate of
neutrino-nucleus interactions at different neutrino energies or different
distances from the source. Knowledge of the neutrino energy spectrum and
neutrino-detector interactions are crucial for these experiments. Short range
nucleon-nucleon correlations in nuclei (SRC) affect properties of nuclei. The
ArgoNeut liquid Argon Time Projection Chamber (lArTPC) observed neutrino-argon
scattering events with two protons back-to-back in the final state ("hammer"
events) which they associated with SRC pairs. The MicroBoone lArTPC will
measure far more of these events.
We simulate hammer events using two simple models. We use the well-known
electron-nucleon cross section to calculate e-argon interactions where the e-
scatters from a proton, ejecting a pi+, and the pi+ is then absorbed on a
moving deuteron-like pair. We also use a model where the electron excites
a nucleon to a Delta, which then deexcites by interacting with a second
nucleon.
The pion production model results in two protons very similar to those of the
hammer events. These distributions are insensitive to the momentum of the
pair that absorbed the . The incident neutrino energy can be reconstructed
from just the outgoing lepton. The Delta process results in two protons that
are less similar to the observed events.
ArgoNeut hammer events can be described by a simple pion production and
reabsorption model. These hammer events in MicroBooNE can be used to determine
the incident neutrino energy but not to learn about SRC. We suggest that this
reaction channel could be used for neutrino oscillation experiments to
complement other channels with higher statistics but different systematic
uncertainties.Comment: Text improved in response to PRC referee comment
Disentangling the EMC Effect
The deep inelastic scattering cross section for scattering from bound
nucleons differs from that of free nucleons.This phenomena, first discovered 30
years ago, is known as the EMC effect and is still not fully understood. Recent
analysis of world data showed that the strength of the EMC effect is linearly
correlated with the relative amount of Two-Nucleon Short Range Correlated pairs
(2N-SRC) in nuclei. The latter are pairs of nucleons whose wave functions
overlap, giving them large relative momentum and low center of mass momentum,
where high and low is relative to the Fermi momentum of the nucleus. The
observed correlation indicates that the EMC effect, like 2N-SRC pairs, is
related to high momentum nucleons in the nucleus. This paper reviews previous
studies of the EMC-SRC correlation and studies its robustness. It also presents
a planned experiment aimed at studying the origin of this EMC-SRC correlation.Comment: 8 pages, 3 figures. Proceedings of plenary talk at CIPANP 201
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