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At least 55 records · Page 3
All sourcesNASA NTRSDOE OSTI
DOE OSTI2021

Measurement of the EMC effect in light and heavy nuclei

In this work, inclusive electron scattering from nuclear targets has been measured to extract the nuclear dependence of the inelastic cross section in Hall C at the Thomas Jefferson National Accelerator facility. Results are presented for 2 H, 3 He, 4 He, 9 B, 12 C, 63 Cu and 197 Au at an incident electron beam energy of 5.77 GeV for a range of momentum transfer from Q 2 = 2 to 7 (GeV/c) 2 . These data improve the precision of the existing measurements of the EMC effect in the nuclear targets at large x, and allow for more detailed examinations of the A dependence of the EMC effect.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2017

Short-Range Correlations and the EMC Effect in Effective Field Theory

We propose that the empirical linear relation between the magnitude of the EMC effect in deep inelastic scattering on nuclei and the short-range correlation scaling factor a 2 extracted from high-energy quasielastic scattering at x ≥ 1 is a natural consequence of scale separation and derive the relationship using effective field theory. While the scaling factor a 2 is a ratio of nuclear matrix elements that individually depend on the calculational scheme, we show that the ratio is independent of this choice. We perform Green’s function Monte Carlo calculations with both chiral and Argonne-Urbana potentials to verify this and determine the scaling factors for light nuclei. The resulting values for 3 He and 4 He are in good agreement with experimental values. We additionally present results for 9 Be and 12 C extracted from variational Monte Carlo calculations.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2011

The EMC effect in the few-body bound states

The deep inelastic scattering of leptons off nuclei is studied within the the Bethe-Salpeter formalism. It is shown that nuclear short-range structure can be expressed in terms of the nucleon structure functions and four-dimensional Fermi motion of the nucleons. The four-dimensional Fermi motion broadens the bound nucleon localization area, what leads to the observation of the nucleon structure change in nuclei--EMC effect. The {sup 4}He to deuteron structure functions ratio is found in good agreement with experimental data. It is shown that the pattern of the ratio is defined by dynamical properties of the nucleon structure and four-dimensional geometry of the bound state.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2011

Semi-inclusive deep-inelastic scattering off few-nucleon systems: Tagging the EMC effect and hadronization mechanisms with detection of slow recoiling nuclei

The semi-inclusive deep-inelastic scattering of electrons off {sup 2}H and {sup 3}He with detection of slow protons and deuterons, respectively, i.e., the processes {sup 2}H(e,e{sup '}p)X and {sup 3}He(e,e{sup '}d)X, are calculated within the spectator mechanism, taking into account the final state interaction of the nucleon debris with the detected protons and deuterons. It is shown that by a proper choice of the kinematics the origin of the EMC effect and the details of the interaction between the hadronizing quark and the nuclear medium can be investigated at a level which cannot be reached by inclusive deep-inelastic scattering. A comparison of the results of our calculations, containing no adjustable parameters, with recently available experimental data on the process {sup 2}H(e,e{sup '}p)X shows a good agreement in the backward hemisphere of the emitted nucleons. Theoretical predictions at energies that will be available at the upgraded Thomas Jefferson National Accelerator Facility are presented, and the possibility to investigate the proposed semi-inclusive processes at electron-ion colliders is briefly discussed.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2015

First Search for the EMC Effect and Nuclear Shadowing in Neutrino Nucleus Deep Inelastic Scattering at MINERvA

Decades of research in electron-nucleus deep inelastic scattering (DIS) have provided a clear picture of nuclear physics at high momentum transfer. While these effects have been clearly demonstrated by experiment, the theoretical explanation of their origin in some kinematic regions has been lacking. Particularly, the effects in the intermediate regions of Bjorken-x, anti-shadowing and the EMC effect have no universally accepted quantum mechanical explanation. In addition, these effects have not been measured systematically with neutrino-nucleus deep inelastic scattering, due to experiments lacking multiple heavy targets.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2014

The challenge of the EMC effect: Existing data and future directions

Since the discovery that the ratio of inclusive charged lepton (per-nucleon) cross sections from a nucleus A to the deuteron is not unity - even in deep inelastic scattering kinematics - a great deal of experimental and theoretical effort has gone into understanding the phenomenon. The EMC effect, as it is now known, shows that even in the most extreme kinematic conditions the effects of the nucleon being bound in a nucleus can not be ignored. In this paper we collect the most precise data available for various nuclear to deuteron ratios, as well as provide a commentary on the current status of the theoretical understanding of this thirty year old effect.

Malace, Simona P.↗
DOE OSTI2012

High-momentum components of the nuclear wave function: Short range correlations, EMC effect, and the tensor parts of the N-N interaction

The combination of inclusive and exclusive electron scattering data from JLab in kinematic regimes that were not reachable before, together with the analysis and interpretation of older data from hadronic reactions at BNL is finally revealing the details of short-range nucleon-nucleon correlations in nuclei. The most significant result is the demonstration of the dominance of correlated np pairs over pp and nn pairs. I will review these results, discuss them in terms of short-range tensor-force dominance and also discuss the connection to the EMC effect.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2022

Precise measurement of the nuclear dependence of the EMC effect in light nuclei

Measurements of inclusive electron scattering cross-section ratios from light nuclei over a wide range of the Björken G (0.3 ? G ? 1) up to &2 = 8.3 GeV2 were made as part of experiment E10-10-008, which was conducted in Hall C at the Thomas Jefferson National Accelerator Facility. The measurements were performed using a beam energy of 10.602 GeV and an average beam current of 45 `A. This dissertation provides a thorough description of the experiment as well as the extracted ratios of inclusive nuclear cross-sections with respect to the deuterium cross-sections (the EMC effect) for the targets 9Be, 12C, 10B, and 11B. The nuclear dependence of the inclusive inelastic electron scattering cross-section has been measured for the first time in 10B and 11B.

Karki, Abishek↗
DOE OSTI2011

Light Cone Dynamics and EMC Effects in the Extraction of F{sub 2n} at Large Bjorken x

We discuss theoretical issues related to the extraction of deep inelastic (DIS) structure function of neutron from inclusive DIS scattering off the deuteron at large Bjorken x. Theoretical justification is given to the consideration of only pn component of the deuteron wave function and consistency with both the baryonic number and light-cone momentum conservation sum rules. Next we discuss the EMC type effects and argue that in all cases relevant to the nuclear DIS reactions at large x the main issue is the medium modification of the properties of bound nucleon rather than the non-nucleonic components like pions. We give brief description of the color screening model of EMC and within this model we estimate uncertainties in the extraction of the neutron DIS structure function at large x. We emphasize also that these uncertainties are rather ''model independent'' since any theoretical framework accounting for the medium modification is proportional to the magnitude of the virtuality of bound nucleon which increases with an increase of x.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2026

Isospin dependence of the nuclear EMC effect from a global QCD analysis

We perform a new global QCD analysis of unpolarized parton distribution functions (PDFs) in the nucleon from proton, deuteron, and A = 3 data, including recent measurements of He 3 / D and H 3 / D cross section ratios from the MARATHON experiment at Jefferson Lab. Simultaneously inferring the PDFs and nucleon off-shell corrections allows both to be determined consistently, without theoretical assumptions about the isospin dependence of nuclear effects. The analysis provides strong evidence for the need of nucleon off-shell corrections to describe the A = 3 data, with large isoscalar and a suggestion of nonzero isovector contributions in A ≤ 3 nuclei. We find that the extracted EMC ratios of nuclear to nucleon structure functions for A = 2 and 3 differ from those naively extrapolated from heavy nuclei down to low A .

Cocuzza, C. [William & Mary] (ORCID:00000003492292↗
DOE OSTI2013

The EMC Effect Still Puzzles After 30 Years

Thirty years ago, high-energy muons at CERN revealed the first hints of an effect that puzzles experimentalists and theorists alike to this day.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2018

Quarks in the Nucleus - Recent Results and Future Measurements at Jefferson Lab

A major part of the Jefferson Lab experimental program has been to elucidate the role of quarks in the nucleus. Since the 1980's, we have known that the distribution of quarks in the nucleus is not the same as in the free proton and neutron. This modification of quark distributions, known as the EMC Effect, has been the subject of much experimental study for more than 30 years. Results from the 6 GeV Jefferson Lab program showed that the EMC Effect appears to depend on the local, rather than average, nuclear density. In addition, it was found that a seemingly unrelated quantity, the number of protons and neutrons found to be in a correlated pair in the nucleus (Short Range Correlations), shares the same nuclear dependence as the EMC Effect. In this presentation I will review the Jefferson Lab 6 GeV measurements that provided exciting hints as to the origin of the EMC Effect and its connection with Short Range Correlations. In addition, I will discuss the program of measurements planned as part of the 12 GeV program that will further explore this EMC-SRC connection and provide crucial insight into the role of quarks and nucleons in the nucleus.

Pooser, Eric↗