scholarly journals On the quenching of Gamow–Teller strength

1987 ◽  
Vol 65 (6) ◽  
pp. 574-577 ◽  
Author(s):  
J. Rapaport
Keyword(s):  
Cross Sections ◽  
Wave Functions ◽  
Light Nuclei ◽  
Final States ◽  
Excitation Energies ◽  
Intermediate Energies ◽  
Quenching Factor ◽  
Configuration Mixing ◽  
Gamow Teller ◽  
Model Strength

The (p, n) reaction at intermediate energies has been used to measure differential cross sections in light nuclei to final states characterized with a ΔJπ = 1+ transfer (Gamow–Teller (GT) states). Experimental ft values for allowed beta-decay transitions in these nuclei are used to normalize the strength of the GT transitions in units of B(GT). This experimental GT strength is compared with predicted shell–model strength. For p-shell nuclei, the calculated excitation energies of the GT strength using Cohen and Kurath wave functions are in general agreement with the empirical GT distribution. Up to an excitation energy of about 20 MeV, the total experimental and calculated GT strengths are used to obtain the quenching factor, QF = Σ B(GT)exp/Σ B(GT)theor. It is found that QF decreases as the shell gets filled-up. The lowest value seems to occur for single-hole nuclei. This decrease may be explained by configuration mixing not specifically included in the calculations.

Direct Photodisintegration of 9Be in the Low and Sub-Giant Resonance Energy Region

1969 ◽  
Vol 24 (8) ◽  
pp. 1188-1195
Author(s):  
Terje Aurdal
Keyword(s):  
Cross Sections ◽  
Giant Resonance ◽  
Resonance Energy ◽  
Wave Functions ◽  
Nuclear Model ◽  
Final States ◽  
Core State ◽  
Radial Wave ◽  
Total Cross Sections ◽  
Reaction Channels

Abstract Photodisintegration cross sections for the reaction 9Be(γ,n) 8Be with photonenergies varied from threshold to about 17 MeV are calculated. As nuclear model is assumed a single particle shell model where the valence neutron outside the 8Be core is feeling a spherical field. The core state is assumed to be a mixture of the ground (0+) and the first excited (2+) state of the 8Be nucleus. The total cross sections are splitted up according to the different contributing reaction channels. The radial wave functions in initial as well as final states are of the Saxon-Woods type.

Gamow–Teller strength functions from scattering experiments

1987 ◽  
Vol 65 (6) ◽  
pp. 691-698 ◽  
Author(s):  
O. Häusser
Keyword(s):  
Shell Model ◽  
Cross Sections ◽  
Mean Field ◽  
Wave Functions ◽  
Structure Information ◽  
Model Wave ◽  
Spin Flip ◽  
Strength Functions ◽  
Gamow Teller ◽  
Good Agreement

We present here recent [Formula: see text] results from TRIUMF that are relevant to the determination of spin-flip isovector strength functions in nuclei. Distortion factors needed for the extraction of nuclear-structure information have been deduced from cross sections and analyzing powers in elastic scattering for several energies and targets. Nonrelativistic optical potentials obtained by folding effective nucleon (N)–nucleus interactions with nuclear densities are found to overpredict both elastic and reaction cross sections, whereas Dirac calculations that include Pauli blocking are in good agreement with the data. Spin observables (Snn and Ay) for the quasi-elastic region in 54Fe[Formula: see text] at 290 MeV provide some evidence for the reduction of the effective proton mass predicted in relativistic mean-field theories as a consequence of the attractive scalar field in the nuclear medium. The energy dependence of the effective N–nucleus interaction at small momentum transfers has been investigated using isoscalar and isovector 1+ states in 28Si as probe states. We find that the cross sections for the isovector transitions are in good agreement with predictions for the dominant Vστ part of the Franey–Love interaction. Gamow–Teller (GT) strength functions have been obtained in 24Mg and 54Fe from measurements of both cross sections and spin–flip probabilities Snn. The spin-flip cross sections σSnn are particularly useful in heavier nuclei to discriminate against a continuous background of ΔS = 0 excitations. In the (s, d) shell where full shell-model wave functions are available, the GT quenching factors [Formula: see text] are in good agreement with those from recent (p, n) and (n, p) experiments. We show that a state-by-state comparison of (p, p′) and (e, e′) results has the potential of identifying pionic current contributions in (e, e′). The GT quenching factors in 54Fe are smaller than in the (s, d) shell probably because of severely truncated shell-model wave functions, particularly those of the nuclear ground state.

scholarly journals NUCLEAR MEAN-FIELD DESCRIPTION OF PROTON ELASTIC SCATTERING BY 12,13 C AT LOW ENERGIES

2020 ◽  
Vol 31 (1) ◽  
Author(s):  
Huan Nhut Phan
Keyword(s):  
Elastic Scattering ◽  
Cross Sections ◽  
Nuclear Reactions ◽  
Mean Field ◽  
Nuclear Astrophysics ◽  
Nucleon Nucleon ◽  
Light Nuclei ◽  
Intermediate Energies ◽  
Proton Elastic Scattering ◽  
Low Energies

Nuclear reactions of proton by light nuclei at low energies play a key role in the study ofnucleosynthesis which is of interest in nuclear astrophysics. The most fundamental process whichis very necessary is the elastic scattering. In this work, we construct a microscopic proton-nucleuspotential in order to describe the differential cross-sections over scattering angles of the protonelastic scattering by 12C and 13C in the range of available energies 14 - 22 MeV. The microscopicoptical potential is based on the folding model using the effective nucleon-nucleon interactionCDM3Yn. The results show the promising use of the CDM3Yn interactions at low and very lowenergies, which were originally used for nuclear reactions at intermediate energies. This could bethe premise for the study of nuclear reactions using CDM3Yn interaction in astrophysics at lowenergies.

Nuclear structure dependence in analyzing powers?

1980 ◽  
Vol 58 (12) ◽  
pp. 1686-1690 ◽  
Author(s):  
W. R. Falk
Keyword(s):  
Nuclear Structure ◽  
Cross Sections ◽  
Form Factors ◽  
Wave Functions ◽  
Angular Distributions ◽  
Structure Dependence ◽  
Analyzing Powers ◽  
Wide Range ◽  
Configuration Mixing ◽  
The Cross

Calculations of the angular distributions of the cross-sections and analyzing powers in the [Formula: see text] Al reaction have been made using microscopic form factors. A wide range of shapes of the microscopic form factors, simulating different degrees of configuration mixing in the nuclear wave functions, fail to provide angular distributions of the analyzing powers that agree with experiment for the 2.73 and 4.41 MeV, 5/2+ states.

scholarly journals Neutral current neutrino-94Mo scattering in the context of the QRPA method

2019 ◽  
Vol 18 ◽  
pp. 31
Author(s):  
K. G. Balasi ◽  
T. S. Kosmas
Keyword(s):  
Cross Sections ◽  
Random Phase Approximation ◽  
Neutral Current ◽  
Random Phase ◽  
Reaction Rates ◽  
Systematic Investigation ◽  
Wave Functions ◽  
Phase Approximation ◽  
Quasi Particle ◽  
Intermediate Energies

A systematic investigation of neutrino-nucleus reaction rates at low and intermediate energies of the stable 94Mo isotope is performed. Differential and integrated cross sections for neutrino inelastic scattering off the aforementioned target are calculated for neutrino energies εi ≼ 100 MeV. The nuclear wave functions for the initial and final nuclear states are constructed in the context of the quasi-particle random phase approximation (QRPA). The reliability of our method is tested by checking the reproducibility of the low-lying energy spectrum of the isotope under investigation.

Resonance charge transfer between H(1s) and H + calculated by means of an approximation based on an expansion in atomic eigenfunctions

1961 ◽  
Vol 264 (1319) ◽  
pp. 547-557 ◽  
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Atomic Hydrogen ◽  
High Energy ◽  
Wave Functions ◽  
Final States ◽  
Energy Limit ◽  
Full Account ◽  
The Cross ◽  
Resonance Charge

An expression for the cross-section describing electron capture by protons in atomic hydrogen is derived from an expansion based on atomic wave functions. Full account is taken of momentum transfer and of the non-orthogonality of the wave functions of the initial and final states by the method due to Bates. The cross-sections have been computed for proton energies from 100 to 1 MeV. In the low energy limit, the results agree with the p.s.s. calculations of Dalgarno & Yadav and in the high energy limit with the calculations of Brinkm an & Kramers.

Gamow–Teller matrix elements in light nuclei and (p,n) cross sections at Ep = 35 MeV

2002 ◽  
Vol 539 (1-2) ◽  
pp. 40-45 ◽  
Author(s):  
H Orihara ◽  
A Terakawa ◽  
K Itoh ◽  
H Suzuki ◽  
K Kumagai ◽  
...  
Keyword(s):  
Cross Sections ◽  
Light Nuclei ◽  
Matrix Elements ◽  
Gamow Teller

Puzzle for the existence of 3α + N structure in A=13 system

2006 ◽  
Vol 21 (31n33) ◽  
pp. 2411-2417 ◽  
Author(s):  
Mamoru Fujiwara ◽  
Hisako Fujimura
Keyword(s):  
Excited States ◽  
High Energy ◽  
Branching Ratios ◽  
Wave Functions ◽  
Direct Reaction ◽  
View Point ◽  
Intermediate Energies ◽  
Zero Degree ◽  
Bombarding Energy ◽  
Gamow Teller

Spin-isospin excitations in 13 N have been studied by means of the (3 He ,t) and (3 He ,tp) reactions at the bombarding energy of E(3 He ) = 450 MeV . The zero-degree (3 He ,t) spectrum is found to be similar to those from the (p,n) reactions at intermediate energies, suggesting a simple direct reaction mechanism at E(3 He ) = 450 MeV . Three pairs of Gamow-Teller (GT) states with Jπ = 1/2- and 3/2- have been strongly excited at θlab. = 0°. Microscopic structures of the states in 13 N have been studied by observing decay protons in coincidence with high energy tritons measured at θlab. = 0°. The branching ratios for proton decay from the GT states in 13 N to the final low-lying T =0 states in 12 C were obtained. The wave functions of the excited states in 13 N are discussed in the view point of α cluster model.

scholarly journals Inclusive neutrino-nucleus reaction cross sections at intermediate energies

2020 ◽  
Vol 5 ◽  
pp. 29
Author(s):  
T. S. Kosmas ◽  
E. Oset
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Reaction Cross ◽  
Point Of View ◽  
Electron Neutrino ◽  
Muon Capture ◽  
Light Nuclei ◽  
Experimental Point ◽  
Intermediate Energies ◽  
Reaction Cross Sections

Inclusive neutrino-nucleus reaction cross sections at intermediate energies (20 MeV < Ey < 500 MeV) are calculated throughout the periodic table for the most interesting nu­ clei from an experimental point of view. The method used had previously proved to be very accurate in calculating the induced reaction cross section for T=0 light nuclei (12C and 16O) and in the study of other similar processes like the ordinary muon capture. The electron-neutrino (ve) cross section weighted by the Michel distribution is also discussed in conjuction with the existing experimental results at LAMPF and ΚARMEN.

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