THE ANGULAR DISTRIBUTION OF THE Li7(t, α)He6 REACTIONS AT 240 KEV. TRITON ENERGY

1954 ◽  
Vol 32 (10) ◽  
pp. 621-629 ◽  
Author(s):  
E. Almqvist ◽  
T. P. Pepper ◽  
P. Lorrain
Keyword(s):  
Excited State ◽  
Ground State ◽  
Center Of Mass ◽  
Angular Distributions ◽  
Laboratory System ◽  
Mass System ◽  
Compound State ◽  
First Excited State ◽  
State Spin ◽  
Α Particles

The angular distributions of the Li7(t, α)He6 reactions have been measured between 41° and 139° to the beam in the laboratory system. The distribution of the 5.95 Mev. α-particles associated with the formation of ground state He6 is of the form [Formula: see text] in the center of mass system. The 4.95 Mev. α-particles associated with the formation of the first excited state of He6 are distributed isotropically within ±8%. These results are consistent with the expectation that the ground state of He6 has spin 0 and the first excited state spin 2 and suggest that the compound state, Be10, has J = 2.

Neutrons from Deuteron Bombardment of Boron

1957 ◽  
Vol 10 (2) ◽  
pp. 268 ◽  
Author(s):  
JR Bird ◽  
RH Spear
Keyword(s):  
Excited State ◽  
Compound Nucleus ◽  
Ground State ◽  
Angular Distributions ◽  
Particle Model ◽  
Upper Limit ◽  
First Excited State ◽  
Compound Nucleus Formation ◽  
Deuteron Bombardment ◽  
Peak Widths

A natural boron target has been bombarded by 920 keV deuterons, and the emitted neutrons detected using nuclear emulsions. A new procedure for analysing measurements is described ; this procedure allows approximate corrections for errors in geometry in the plane of the emulsions. The dependence of resolution on various experimental factors has been studied, and the resolution achieved is indiCated by peak widths of 245 � 25keV and 360 � 50 keV at neutron energies of 9�7 MeV and 13�9 MeV respectively. The angular distributions of the neutrons from the 10B(d,n)l1C reaction corresponding to the ground state of 11C, and the neutrons from the 11B(d,n)12C reaction corresponding to the 7�66 Me V state in 12C, have been determined; both distributions may be attributed to compound nucleus formation. A search has been made for a neutron group corresponding to an excited state at about 5�5 MeV in 12C suggested by Glassgold and Galonsky (1956) on the basis of the a-particle model. An upper limit for the intensity of any such group is set at 1 per cent. of the intensity of the group corresponding to the first excited state in 12C.

SOME PROPERTIES OF THE 2.23-MEV EXCITED STATE OF P31

1959 ◽  
Vol 37 (1) ◽  
pp. 53-62 ◽  
Author(s):  
A. E. Litherland ◽  
G. A. Bartholomew ◽  
H. E. Gove ◽  
E. B. Paul
Keyword(s):  
Angular Momentum ◽  
Excited State ◽  
Gamma Rays ◽  
Ground State ◽  
Total Angular Momentum ◽  
Gamma Ray ◽  
Triple Correlation ◽  
Compound State ◽  
First Excited State ◽  
Coincidence Measurements

The 2.23-Mev excited state of P31 has been studied by means of the capture gamma rays from the 1.70-Mev resonance in the reaction Si30(pγ)P31. The angular correlation of the ground state gamma ray established that the resonance had total angular momentum 3/2, and triple correlation measurements of the cascading gamma rays from the compound state showed that the angular momentum of the 2.23-Mev state was 5/2. Coincidence measurements showed that the cascade gamma rays from the 2.23-Mev state to the first excited state at 11.27-Mev were [Formula: see text] of the transitions to the ground state.

Bremsstrahlung and Pair Production in the Field of Free Electrons

1975 ◽  
Vol 30 (9) ◽  
pp. 1099-1113 ◽  
Author(s):  
E. Haug
Keyword(s):  
Pair Production ◽  
Cross Section ◽  
Theoretical Calculations ◽  
Center Of Mass ◽  
Energy Spectra ◽  
Angular Distributions ◽  
Laboratory System ◽  
Free Electrons ◽  
Substitution Rule ◽  
Mass System

A formula is given for the doubly differential cross section of electron-electron bremsstrahlung which is exact in lowest-order perturbation theory. Angular distributions and energy spectra of the emitted photon are calculated in the center-of-mass system and the laboratory system. The cross section for pair production in the field of an electron (triplet production) can be derived from the analogous bremsstrahlung formula using the substitution rule. Angular distributions and energy spectra of the produced positron as well as the total cross section for triplet production are computed in the laboratory system. The results for bremsstrahlung and pair production are compared with previous theoretical calculations

A meta-analysis and review examining a possible role for oxidative stress and singlet oxygen in diverse diseases

2017 ◽  
Vol 474 (16) ◽  
pp. 2713-2731 ◽  
Author(s):  
Athinoula L. Petrou ◽  
Athina Terzidaki
Keyword(s):  
Oxidative Stress ◽  
Excited State ◽  
Singlet Oxygen ◽  
Ground State ◽  
Meta Analysis ◽  
Common Mechanism ◽  
High Electron ◽  
A Value ◽  
First Excited State

From kinetic data (k, T) we calculated the thermodynamic parameters for various processes (nucleation, elongation, fibrillization, etc.) of proteinaceous diseases that are related to the β-amyloid protein (Alzheimer's), to tau protein (Alzheimer's, Pick's), to α-synuclein (Parkinson's), prion, amylin (type II diabetes), and to α-crystallin (cataract). Our calculations led to ΔG≠ values that vary in the range 92.8–127 kJ mol−1 at 310 K. A value of ∼10–30 kJ mol−1 is the activation energy for the diffusion of reactants, depending on the reaction and the medium. The energy needed for the excitation of O2 from the ground to the first excited state (1Δg, singlet oxygen) is equal to 92 kJ mol−1. So, the ΔG≠ is equal to the energy needed for the excitation of ground state oxygen to the singlet oxygen (1Δg first excited) state. The similarity of the ΔG≠ values is an indication that a common mechanism in the above disorders may be taking place. We attribute this common mechanism to the (same) role of the oxidative stress and specifically of singlet oxygen, (1Δg), to the above-mentioned processes: excitation of ground state oxygen to the singlet oxygen, 1Δg, state (92 kJ mol−1), and reaction of the empty π* orbital with high electron density regions of biomolecules (∼10–30 kJ mol−1 for their diffusion). The ΔG≠ for cases of heat-induced cell killing (cancer) lie also in the above range at 310 K. The present paper is a review and meta-analysis of literature data referring to neurodegenerative and other disorders.

Extended Hartree–Fock Calculations for the Ground State and Hartree–Fock Calculations for the First Excited State of H2

1970 ◽  
Vol 53 (7) ◽  
pp. 2743-2749 ◽  
Author(s):  
Joseph D. Bowman ◽  
Joseph O. Hirschfelder ◽  
Arnold C. Wahl
Keyword(s):  
Excited State ◽  
Ground State ◽  
Hartree Fock ◽  
First Excited State

LIFETIME MEASUREMENTS OF STATES IN O18 AND Ne22

1964 ◽  
Vol 42 (6) ◽  
pp. 1311-1323 ◽  
Author(s):  
M. A. Eswaran ◽  
C. Broude
Keyword(s):  
Excited State ◽  
Ground State ◽  
Doppler Shift ◽  
State Transition ◽  
Branching Ratios ◽  
Ground State Transition ◽  
Lifetime Measurements ◽  
Doppler Shift Attenuation ◽  
First Excited State ◽  
Doppler Shift Attenuation Method

Lifetime measurements have been made by the Doppler-shift attenuation method for the 1.98-, 3.63-, 3.92-, and 4.45-Mev states in O18 and the 1.28-, 3.34-, and 4.47-Mev states in Ne22, excited by the reactions Li7(C12, pγ)O18 and Li7(O16, pγ)Ne22. Branching ratios have also been measured. The results are tabulated.[Formula: see text]The decay of the 3.92-Mev state in O18 is 93.5% to the 1.98-Mev state and 6.5% to the ground state and of the 4.45-Mev state 74% to the 3.63-Mev state, 26% to the 1.98-Mev state, and less than 2% to the ground state. In Ne22, the ground-state transition from the 4.47-Mev state is less than 2% of the decay to the first excited state.

Enhance decay of the analogue resonance of the 107Cd ground state to the first excited state of 106Cd

1968 ◽  
Vol 26 (12) ◽  
pp. 723-726 ◽  
Author(s):  
E. Abramson ◽  
I. Plesser ◽  
Z. Vager
Keyword(s):  
Excited State ◽  
Ground State ◽  
First Excited State ◽  
Analogue Resonance

The 12 C(γ, 3α) reaction energy levels of 8 Be and 12 C

1955 ◽  
Vol 228 (1174) ◽  
pp. 376-396 ◽  
Keyword(s):  
Ground State ◽  
Energy Levels ◽  
Electric Quadrupole ◽  
Angular Distributions ◽  
Reaction Energy ◽  
Reaction Proceeds ◽  
Γ Ray ◽  
Relationship Of ◽  
The Relationship ◽  
Α Particles

The mechanism of the 12 C(γ, 3α) reaction, for γ-ray energies, E γ , up to about 40 MeV, has been determined from a study of over 2500 stars in nuclear emulsions. The study includes investigation of the angular distributions and correlations of the α-particles. The reaction is initiated mainly by electric-dipole and electric-quadrupole γ-ray interaction, the former being unexpectedly strong when E γ < 20 MeV. For E γ < 25 MeV the reaction proceeds mainly by transitions to the ground-state of 8 Be (spin J = 0), and to 2⋅95 ± 0⋅10 MeV ( J = 2) and 4⋅0 ± 0⋅1 MeV ( J = 2 or 4) levels of 8 Be. Transitions to levels near 6, 10 and 15 MeV (all J = 0, 2 or 4) become predominant when 25 MeV ≤ E γ <26 MeV. For E γ ≥ 26 MeV, most transitions lead to 16⋅8 ± 0⋅2 MeV ( J = 2) and 17⋅6 ± 0⋅2 MeV ( J = 2, possibly 0) levels, and possibly to a further 16⋅4 ± 0⋅2 MeV ( J = 0 or 2) level, levels which have not been detected in other reactions. The reaction mechanism is interpreted in terms of competing modes of decay of a compound nucleus, demonstrating the strong influence of the isotopic spins ( T ) of the levels of 12 C and 8 Be involved. For example, the 2 + levels of 12 C involved when 16 MeV ≤ E γ <20 MeV are (unexpectedly) found to have T = 1, and the 16⋅8 and 17⋅6 MeV levels of 8 Be are also found to have T = 1. The relationship of the 12 C (γ, 3α) reaction to other 12 C photodisintegration reactions (including some new reactions established during the present experiments) is discussed.

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