scholarly journals Masses and Beta-decay Studies of Neutron-rich Nuclei using the X-array and Gammasphere

2019 ◽  
Vol 223 ◽  
pp. 01028
Author(s):  
F.G. Kondev ◽  
D.J. Hartley ◽  
R. Orford ◽  
J.A Clark ◽  
G. Savard ◽  
...  
Keyword(s):  
Nuclear Structure ◽  
Nuclear Physics ◽  
Penning Trap ◽  
National Laboratory ◽  
Argonne National Laboratory ◽  
Theoretical Models ◽  
Radioactive Beam ◽  
Experimental Program ◽  
Particle Structure ◽  
Rare Isotope

Properties of neutron-rich nuclei in the A˜160 region are important for achieving a better understanding of the nuclear structure in this region where little is known owing to diffculties in the production of these nuclei at the present nuclear physics facilities. These properties are essential ingredients in the interpretation of the rareearth peak at A˜160 in the r process abundance distribution, since theoretical models are sensitive to nuclear structure input. Predicated on these ideas, we have initiated a new experimental program at Argonne National Laboratory. During the first experiment, beams from the Californium Rare Isotope Breeder Upgrade radioactive beam facility were used in conjunction with the SATURN decay station and the X-array. We focused initially on several odd-odd nuclei, where β decays of both the ground state and an excited isomer were investigated. Because of the spin difference, a variety of structures in the daughter nuclei were selectively populated and characterized based on their decay properties. Mass measurements using the Canadian Penning Trap aimed at establishing the excitation energy of the β-decaying isomers were also carried out. Evidence was found for a change in the single-particle structure, which in turn results in the formation of a sizable N=98 sub-shell gap at large deformation. Results from the first experimental campaign using the newly-commissioned β-decay station at Gammasphere are also presented.

A Theoretical and Experimental Study of the Vibratory Behavior of a High-Precision Optical Positioning Table

1997 ◽  
Author(s):  
Ipek Basdogan ◽  
Thomas J. Royston ◽  
Juan Barraza ◽  
Deming Shu ◽  
Tuncer M. Kuzay
Keyword(s):  
High Precision ◽  
Dynamic Properties ◽  
National Laboratory ◽  
Argonne National Laboratory ◽  
Theoretical Models ◽  
Positioning Systems ◽  
Wide Range ◽  
Optical Table ◽  
The Individual ◽  
Optical Positioning

Abstract At the Advanced Photon Source (APS), a state-of-the-art synchrotron radiation facility at Argonne National Laboratory (ANL), high-precision optical positioning systems are needed to conduct a wide range of experiments utilizing the high-brilliance x-ray beam. The high-precision, multi-dimensional positioning capability required for these positioning systems may be compromised by vibratory motion. The vibratory dynamics of the complex kinematic joints and components that comprise these multibody structures are not easily described by simple theoretical models. A combined experimental and theoretical approach has been developed to predict the dynamic properties of the individual components and joints and of the assembled multibody system. A prototypical optical table has been analyzed as an example case.

scholarly journals Beta-decay studies for applied and basic nuclear physics

2021 ◽  
Vol 57 (3) ◽  
Author(s):  
A. Algora ◽  
J. L. Tain ◽  
B. Rubio ◽  
M. Fallot ◽  
W. Gelletly
Keyword(s):  
Nuclear Structure ◽  
Nuclear Physics ◽  
Penning Trap ◽  
Neutron Emission ◽  
Large Impact ◽  
Neutron Separation Energy ◽  
Total Absorption ◽  
Decay Heat ◽  
Neutrino Spectrum ◽  
Absorption Technique

AbstractIn this review we will present the results of recent $$\beta $$ β -decay studies using the total absorption technique that cover topics of interest for applications, nuclear structure and astrophysics. The decays studied were selected primarily because they have a large impact on the prediction of (a) the decay heat in reactors, important for the safety of present and future reactors and (b) the reactor electron anti-neutrino spectrum, of interest for particle/nuclear physics and reactor monitoring. For these studies the total absorption technique was chosen, since it is the only method that allows one to obtain $$\beta $$ β -decay probabilities free from a systematic error called the Pandemonium effect. The total absorption technique is based on the detection of the $$\gamma $$ γ cascades that follow the initial $$\beta $$ β decay. For this reason the technique requires the use of calorimeters with very high $$\gamma $$ γ detection efficiency. The measurements presented and discussed here were performed mainly at the IGISOL facility of the University of Jyväskylä (Finland) using isotopically pure beams provided by the JYFLTRAP Penning trap. Examples are presented to show that the results of our measurements on selected nuclei have had a large impact on predictions of both the decay heat and the anti-neutrino spectrum from reactors. Some of the cases involve $$\beta $$ β -delayed neutron emission thus one can study the competition between $$\gamma $$ γ - and neutron-emission from states above the neutron separation energy. The $$\gamma $$ γ -to-neutron emission ratios can be used to constrain neutron capture (n,$$\gamma $$ γ ) cross sections for unstable nuclei of interest in astrophysics. The information obtained from the measurements can also be used to test nuclear model predictions of half-lives and Pn values for decays of interest in astrophysical network calculations. These comparisons also provide insights into aspects of nuclear structure in particular regions of the nuclear chart.

scholarly journals Texas A&M US Nuclear DATA Program

2021 ◽  
Vol 252 ◽  
pp. 08001
Author(s):  
Ninel Nica
Keyword(s):  
Nuclear Structure ◽  
Nuclear Physics ◽  
World Literature ◽  
National Laboratory ◽  
Nuclear Data ◽  
Data File ◽  
The United States ◽  
Brookhaven National Laboratory ◽  
The Us ◽  
Data Program

Nuclear data evaluation is an independent century-long expert activity accompanying the development of the nuclear physics science. Its goal is to produce periodic surveys of the world literature in order to recommend and maintain the set of the best nuclear data parameters of common use in all basic and applied sciences. After WWII the effort extended and while it became more international it continued to be supported mainly by the US for the benefit of the whole world. The Evaluated Nuclear Structure Data File (ENSDF) is the most comprehensive nuclear structure database worldwide maintained by the United States National Nuclear Data Center(NNDC)at Brookhaven National Laboratory(BNL)and echoed by the IAEA Vienna Nuclear Data Services. Part of the US Nuclear Data Program since 2005 the Cyclotron Institute is one of the important contributors to ENSDF. Since 2018 we became an international evaluation center working in a consortium of peers hosted traditionally by prestigious national institutes as well as universities. In this paper the main stages of the evaluation work are presented in order to facilitate a basic understanding of the process as a guide for our potential users. Our goals are to maintain a good productivity vs. quality performance assuring the currency of the data and participating in the effort of modernizing the structure of ENSDF databases in order to make them compatible with the data-centric paradigms of the future.

Development of the Positron Facility at the Argonne National Laboratory’s 20 MeV Linac

2008 ◽  
Vol 607 ◽  
pp. 243-247 ◽  
Author(s):  
S. Chemerisov ◽  
Charles D. Jonah
Keyword(s):  
Penning Trap ◽  
National Laboratory ◽  
Argonne National Laboratory ◽  
Positron Energy ◽  
Slow Positron ◽  
Order Of Magnitude ◽  
Low Energy Electron ◽  
Further Development ◽  
Positron Production ◽  
Incident Positron

We present an update on positron-facility development at Argonne National Laboratory. We will discuss advantages of using low energy electron accelerator, present our latest results on slow positron production simulations, and plans for further development of the facility. We have installed a new converter/moderator assembly that is appropriate for our electron energy and that allows increasing the yield about an order of magnitude. We have obtained a Penning trap and buncher from LLNL that we plan to install. We have simulated the relative yields of thermalized positrons as a function of incident positron energy on the moderator. We use these data to calculate positron yields that we compare with our experimental data as well as with available literature data. We will discuss the new design of the next generation positron front end utilizing reflection moderation geometry.

Electron and ion irradiation-induced dissolution of mechanical twins in the intermetalic U3Si: An in situ HVEM study

1989 ◽  
Vol 47 ◽  
pp. 652-653
Author(s):  
Charles W. Allen ◽  
Robert C. Birtcher
Keyword(s):  
Elevated Temperatures ◽  
Ion Irradiation ◽  
Ion Beam ◽  
National Laboratory ◽  
Argonne National Laboratory ◽  
Heavy Ion ◽  
High Energy ◽  
Mechanical Twinning ◽  
In Situ Experiments

The uranium silicides, including U3Si, are under study as candidate low enrichment nuclear fuels. Ion beam simulations of the in-reactor behavior of such materials are performed because a similar damage structure can be produced in hours by energetic heavy ions which requires years in actual reactor tests. This contribution treats one aspect of the microstructural behavior of U3Si under high energy electron irradiation and low dose energetic heavy ion irradiation and is based on in situ experiments, performed at the HVEM-Tandem User Facility at Argonne National Laboratory. This Facility interfaces a 2 MV Tandem ion accelerator and a 0.6 MV ion implanter to a 1.2 MeV AEI high voltage electron microscope, which allows a wide variety of in situ ion beam experiments to be performed with simultaneous irradiation and electron microscopy or diffraction.At elevated temperatures, U3Si exhibits the ordered AuCu3 structure. On cooling below 1058 K, the intermetallic transforms, evidently martensitically, to a body-centered tetragonal structure (alternatively, the structure may be described as face-centered tetragonal, which would be fcc except for a 1 pet tetragonal distortion). Mechanical twinning accompanies the transformation; however, diferences between electron diffraction patterns from twinned and non-twinned martensite plates could not be distinguished.

Environmental cell studies of deformation and fracture

1990 ◽  
Vol 48 (4) ◽  
pp. 516-517
Author(s):  
H. K. Birnbaum ◽  
I. M. Robertson
Keyword(s):  
National Laboratory ◽  
Argonne National Laboratory ◽  
Damage Threshold ◽  
Chromatic Aberration ◽  
Good Choice ◽  
Point Of View ◽  
Deformation And Fracture ◽  
Environmental Cell ◽  
Gas Molecules ◽  
The University

Studies of the effects of hydrogen environments on the deformation and fracture of fcc, bcc and hep metals and alloys have been carried out in a TEM environmental cell. The initial experiments were performed in the environmental cell of the HVEM facility at Argonne National Laboratory. More recently, a dedicated environmental cell facility has been constructed at the University of Illinois using a JEOL 4000EX and has been used for these studies. In the present paper we will describe the general design features of the JEOL environmental cell and some of the observations we have made on hydrogen effects on deformation and fracture.The JEOL environmental cell is designed to operate at 400 keV and below; in part because of the available accelerating voltage of the microscope and in part because the damage threshold of most materials is below 400 keV. The gas pressure at which chromatic aberration due to electron scattering from the gas molecules becomes excessive does not increase rapidly with with accelerating voltage making 400 keV a good choice from that point of view as well. A series of apertures were placed above and below the cell to control the pressures in various parts of the column.

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