scholarly journals 3+ States of 8Be

1978 ◽  
Vol 31 (4) ◽  
pp. 239 ◽  
Author(s):  
FC Barker ◽  
Nasima Ferdous
Keyword(s):  
Matrix Element ◽  
Phase Shift ◽  
Excitation Energy ◽  
Cross Sections ◽  
Qualitative Agreement ◽  
Energy Difference ◽  
Mixing Model ◽  
R Matrix ◽  
Mixing Matrix ◽  
The Cross

Level parameters for the 3+ doublet at about 19 MeV in "Be are obtained from a two-level R-matrix fit to the 7Li+p 5P3 phase shift, using the restrictions of the two-state isospin mixing model. The energy of the lower level is appreciably below the accepted value. Predicted contributions from the 3 + levels to the cross sections for the reactions 7Li(p, n), 7Li(p, y), lOBed, ex) and 9Be(d, t) are compared with measured values, and qualitative agreement is obtained. The new values of the level parameters give agreement with values of the isospin mixing matrix element and of the excitation energy difference of the 3 +, T = 1 states in "Li and "Be, calculated assuming that the charge-dependent nteraction is purely Coulomb.

GT± STRENGTH DISTRIBUTION IN 48Sc AND 116In MEASURED BY (p, n) AND (n, p) REACTIONS AT 300 MeV AND THEIR IMPLICATIONS FOR 2ν2β DECAY

2009 ◽  
Vol 18 (10) ◽  
pp. 2119-2123
Author(s):  
HIDE SAKAI ◽  
KENTARO YAKO ◽  
ICHOR COLLABORATION
Keyword(s):  
Matrix Element ◽  
Excitation Energy ◽  
Cross Sections ◽  
Nuclear Matrix ◽  
Differential Cross ◽  
Nuclear Matrix Element ◽  
Strength Distribution ◽  
Angular Distributions ◽  
Decomposition Technique ◽  
Gamow Teller

Angular distributions of the double differential cross sections for the 48 Ca , 116 Cd (p, n) and the 48 Ti , 116 Sn (n, p) reactions were measured at 300 MeV. A multipole decomposition technique was applied to the spectra to extract the Gamow-Teller (GT) transition strengths. In both (n, p) spectra beyond 8 MeV excitation energy extra B( GT +) strengths which are not predicted by either shell model or QRPA calculations. This extra B( GT +) strengths certainly contribute to the nuclear matrix element of the 2ν2β-decay.

scholarly journals 2- States of 8Be

1977 ◽  
Vol 30 (2) ◽  
pp. 113 ◽  
Author(s):  
FC Barker
Keyword(s):  
Shell Model ◽  
Cross Sections ◽  
Matrix Theory ◽  
Matrix Approximation ◽  
Model Calculations ◽  
R Matrix ◽  
Rapid Changes ◽  
The Cross ◽  
Proper Account

The cross sections for several reactions populating sBe in the region of the 7Be+n threshold show rapid changes, which have been attributed to a 2- threshold state. An analysis of these data using R matrix theory shows that there is considerable isospin mixing in the threshold state, implying another 2 - state nearby. A two-level R matrix approximation provides a good fit to all the relevant data, with parameters consistent with shell model calculations and with properties of sLi. Proper account must be taken of the neutron threshold in order to explain the isospin mixing. The threshold state is expected to show different widths in different reactions.

scholarly journals The Boundary Condition Parameter in R-Matrix Theory

1972 ◽  
Vol 25 (4) ◽  
pp. 341 ◽  
Author(s):  
FO Barker
Keyword(s):  
Boundary Condition ◽  
Finite Number ◽  
Cross Sections ◽  
Nuclear Reactions ◽  
Matrix Theory ◽  
R Matrix ◽  
The Cross

In the general R-matrix theory of nuclear reactions, all measurable quantities such as the cross sections scc' should be independent of the choice of the boundary condition parameters Bc although the values of the level parameters E? and ??c depend on the Bc. For applications involving only a finite number of levels ?, it is not obvious that this is still the case as completeness arguments can no longer be used. It is shown here that scc' can be made independent of the choice Bc of for any finite number of levels and any number of channels, and the resulting formulae giving the dependence of E? and ??c on Bc are derived. An application is made to the pair of 5/2- levels of 7Li near 7 MeV excitation.

CALCULATION OF BREAKUP CROSS SECTION FOR FOUR-BODY BREAKUP REACTION SYSTEMS

2010 ◽  
Vol 25 (21n23) ◽  
pp. 1903-1906
Author(s):  
TAKUMA MATSUMOTO ◽  
KIYOSHI KATŌ ◽  
MASANOBU YAHIRO
Keyword(s):  
Excitation Energy ◽  
Cross Section ◽  
Cross Sections ◽  
Breakup Reaction ◽  
New Method ◽  
Breakup Cross Section ◽  
Reaction Systems ◽  
Coupled Channels ◽  
The Cross

We present a new method of smoothing discrete breakup cross sections calculated by the method of continuum-discretized coupled-channels. In the four-body breakup reaction of 12 C (6 He , nn4 He ) at E in = 229.8 MeV , the continuous breakup cross section is evaluated as a function of the excitation energy of 6 He . Convergence of the cross section with respect to extending the modelspace is also confirmed.

Microscopic calculations for the 4He continuum

1980 ◽  
Vol 58 (3) ◽  
pp. 306-317 ◽  
Author(s):  
J. J. Bevelacqua
Keyword(s):  
Theoretical Model ◽  
Phase Shift ◽  
Harmonic Oscillator ◽  
Qualitative Agreement ◽  
Matrix Formalism ◽  
R Matrix ◽  
Internal States

A detailed theoretical model for the 4He system is constructed within the framework of the dynamical R-matrix formalism of Lane and Robson. The internal states are expanded on a basis of properly symmetrized translationally invariant harmonic oscillator eigenstates including all states up to [Formula: see text] of oscillator excitation. Scattering results for the 3H(p,p), 3He(n,n), 3H(p,n), 2H(d,d), 2H(d,p), and 2H(d,n) reactions are presented. Phase shift calculations for the p + 3H and n + 3He channels suggest a (1+, 0) assignment for the 25.5 MeV level. Detailed scattering calculations are in qualitative agreement with measured results. The results are also compared with resonating group and field theoretic models. Although each model has its advantages, none is able to provide a complete description of the 4He system.

Parity-mixing below 30 MeV excitation energy in the 4He system

1980 ◽  
Vol 58 (2) ◽  
pp. 249-254
Author(s):  
J. J. Bevelacqua
Keyword(s):  
Matrix Element ◽  
Excitation Energy ◽  
Enhancement Factor ◽  
Neutral Current ◽  
Model Space ◽  
Wave Functions ◽  
Matrix Elements ◽  
Least Squares Fit ◽  
Mixing Matrix ◽  
Text Model

Parity-mixing matrix elements for ΔT = 0 and ΔT = 1 transitions are calculated for selected transitions below 30 MeV excitation energy in the 4He system. The effective potential of Box, McKellar, Pick, and Lassey is utilized in the calculations. The results are based on detailed 4He wave functions which are calculated in a [Formula: see text] model space. The calculated parity-mixing matrix elements are in qualitative agreement with those predicted on the basis of a least-squares fit to 2 ≤ A ≤ 181 data by Desplanques and Missimer. The ΔT = 0 matrix element is calculated between the (0+,0)20.1 MeV level and the (0−,0)21.1 MeV level, while the ΔT = 1 matrix element is evaluated between the (1+,0) 25.5 MeV level and the (1−,1) 27.4 MeV state. The ΔT = 0 and ΔT = 1 calculations lead to parity-mixing matrix elements of −0.014 and +0.049 eV, respectively. These matrix elements correspond to parity-mixed components which are 10−8 smaller than the dominant parity component of an energy level. The parity-non-conserving (PNC) transitions lead to circular polarizations of 1.2 × 10−7 for the (1+,0) 25.5 MeV level and −2.2 × 10−8 for the (1−,1) 27.4 MeV level. The inclusion of a neutral current enhancement factor of about 10 increases the ΔT = 1 parity-mixing matrix element by about a factor of two.

The cross sections for different channels in heavy ion nuclear reactions

1971 ◽  
Vol 32 (1) ◽  
pp. 7-9 ◽  
Author(s):  
J. Galin ◽  
D. Guerreau ◽  
M. Lefort ◽  
X. Tarrago
Keyword(s):  
Cross Sections ◽  
Nuclear Reactions ◽  
Heavy Ion ◽  
The Cross

Experimental Studies Of Multilayer Glass Structures On Compression, Compression With Bending And Simple Bending

2019 ◽  
pp. 22-30
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Applied Load ◽  
Experimental Studies ◽  
Strength Properties ◽  
Research Topic ◽  
Normative Values ◽  
Laminated Glass ◽  
The Cross ◽  
Experimental Values

The work of multilayer glass structures for central and eccentric compression and bending are considered. The substantiation of the chosen research topic is made. The description and features of laminated glass for the structures investigated, their characteristics are presented. The analysis of the results obtained when testing for compression, compression with bending, simple bending of models of columns, beams, samples of laminated glass was made. Overview of the types and nature of destruction of the models are presented, diagrams of material operation are constructed, average values of the resistance of the cross-sections of samples are obtained, the table of destructive loads is generated. The need for development of a set of rules and guidelines for the design of glass structures, including laminated glass, for bearing elements, as well as standards for testing, rules for assessing the strength, stiffness, crack resistance and methods for determining the strength of control samples is emphasized. It is established that the strength properties of glass depend on the type of applied load and vary widely, and significantly lower than the corresponding normative values of the strength of heat-strengthened glass. The effect of the connecting polymeric material and manufacturing technology of laminated glass on the strength of the structure is also shown. The experimental values of the elastic modulus are different in different directions of the cross section and in the direction perpendicular to the glass layers are two times less than along the glass layers.

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