Bulletin of the American Physical Society
18th Annual Meeting of the APS Northwest Section,
Volume 62, Number 7
Thursday–Saturday, June 1–3, 2017; Forest Grove, Oregon
Session H3: Nuclear & Particle Physics |
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Room: Price Hall 204 |
Saturday, June 3, 2017 1:30PM - 2:05PM |
H3.00001: Consistent, high-quality two-nucleon potentials up to fifth order of the chiral expansion Invited Speaker: Ruprecht Machleidt We present $NN$ potentials through five orders of chiral effective field theory ranging from leading order (LO) to next-to-next-to-next-to-next-to-leading order (N$^4$LO). The construction is consistent in the sense that the same power counting scheme as well as the same cutoff procedures are applied in all orders. Moreover, the long-range parts of these potentials are fixed by the very accurate $\pi N$ LECs as determined in the Roy-Steiner equations analysis by Hoferichter, Ruiz de Elvira and coworkers. In fact, the uncertainties of these LECs are so small that a variation within the errors leads to effects that are essentially negligible, reducing the error budget of predictions considerably. The $NN$ potentials are fit to the world $NN$ data below pion-production threshold of the year of 2016. The potential of the highest order (N$^4$LO) reproduces the world $NN$ data with the outstanding $\chi^2$/datum of 1.15, which is the highest precision ever accomplished for any chiral $NN$ potential to date. The $NN$ potentials presented may serve as a solid basis for systematic {\it ab initio} calculations of nuclear structure and reactions that allow for a comprehensive error analysis. [Preview Abstract] |
Saturday, June 3, 2017 2:05PM - 2:17PM |
H3.00002: Chiral Effective Field Theory and Nucleonic Matter Francesca Sammarruca The main features and strengths of chiral Effective Field Theory (EFT) can be summarized as follows: 1) the framework of chiral EFT has a firm connection with quantum chromodynamics; 2) it represents a method to generate two- and few-nucleon forces on an equal footing; 3) it allows for systematic improvement of the predictions. High-quality two- and three-nucleon forces have been developed up to fifth and sixth order of chiral EFT. Naturally, the next step is the application of these forces in the many-body system--the goal of {\it ab initio} nuclear physics and a task of formidable complexity. In spite of recent progress, we are still faced with serious problems. One of them concerns the proper quantification of the uncertainty in predictions of structure and reaction observables. A related issue is whether the order-by-order convergence of the chiral expansion in the many-body system is satisfactory. I will illustrate the above problems by way of representative examples of nucleonic matter and nuclear structure issues. Specifically, I will also discuss recent EFT-based predictions of the symmetry energy and the pressure in neutron-rich matter in relation to recent constraints from heavy-ion collisions. [Preview Abstract] |
Saturday, June 3, 2017 2:17PM - 2:29PM |
H3.00003: MuSun: Precision muon capture on the deuteron Ethan Muldoon The MuSun experiment aims to measure the rate for muon capture on the deuteron to 1.5\% precision. This will determine the strength of the weak coupling of the two-nucleon system, which is required to calculate fundamental processes of astrophysical interest such as solar p-p fusion and neutrino-deuteron scattering. The experiment measures the small shift in disappearance rate of muons in $\mu$-d atoms relative to the known free muon decay rate, requiring on the order of 10 billion clean events to reach our precision goal. The experiment utilizes the $\pi$-E1 muon beamline at the Paul Scherrer Institute in Switzerland. Data collection is complete, with production campaigns in 2014 and 2015 recording approximately 12 billion candidate events. Data analysis is under way to address several unique challenges such as high chemical and isotopic target purity, muon beam related backgrounds, and the effect of muon-catalyzed fusion events. Although the capture rate is determined using muon decay electrons, direct measurements of capture and fusion neutrons provide a valuable resource for examining these systematic effects. Here we give an overview of the experiment, and discuss the path towards a high precision result. [Preview Abstract] |
Saturday, June 3, 2017 2:29PM - 2:41PM |
H3.00004: Studies of the SiD Silicon-Tungsten Calorimeter Amanda Steinhebel, James Brau SiD is a detector proposed for the e+e- International Linear Collider (ILC) with a silicon-tungsten sampling electromagnetic calorimeter (ECal). SiD at the ILC will measure the properties of the Higgs boson and top quark with precision beyond the capabilities of the LHC, and search for discoveries of new physics. The ECal boasts extremely high granularity that can separate electromagnetic showers even in busy environments of high energy jets. This is achieved with layers of silicon detectors containing 13 mm$^2$ pixels embedded in thin gaps ($\sim$ 1 mm) between tungsten alloy plates, creating a small but robust detection component. We present the results of simulation studies of the proposed calorimeter with emphasis on the gapless overlap between calorimeter modules. These studies build on the efforts of colleagues in the SiD Optimization group. [Preview Abstract] |
Saturday, June 3, 2017 2:41PM - 2:53PM |
H3.00005: A Characterization of Tri-MeV as a Flash Radiography Device David Housley, Rick Spielman The Tri-MeV electrostatic electron accelerator can deliver a 3 MeV voltage pulse with a current and duration of 30 kA and 20 ns. Up to now available literature $[1]$ suggests the smallest radiographic spot size the Tri-MeV system can produce is 0.8 mm in diameter, being the full width half maximum (FWHM) of the source, with a duration of 19 ns and a dose of 1.2 rad one meter from the source. A recent series of experiments with Tri-MeV have revealed its capability to produce an x-ray burst 5 ns in duration, a dose of 0.7 rad at one meter with a 720 um FWHM x-ray source diameter. In this presentation I will discus x-ray source as observed in this series of experiments.\\ $[1]$ Peter R. Menge, David L, Johnson, John E. Maenchen, Craig L. Olson, and Dean C. Rovang, ``Experimental Comparison of 2-3MV X-ray Sources for Flash Radiography", Sandia National Laboratory Report SAND2002-0082, 2002. [Preview Abstract] |
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