scholarly journals Electric Quadrupole Excitation of the First Excited State of 11B

1980 ◽  
Vol 33 (3) ◽  
pp. 505 ◽  
Author(s):  
MP Fewell ◽  
RH Spear ◽  
TH Zabel ◽  
AM Baxter

The Coulomb excitation of backscattered llB projectiles has been used to measure the reduced E2 transition probability B(E2; 3/2--+ 1/2-) between the 3/2- ground state and the 1/2- first excited state of llB. It is found that B(E2;3/2--+1/2-) = 2�1�0�4 e2 fm4, which agrees with shell model predictions but is a factor of 10 larger than the prediction of the core-excitation model.

1969 ◽  
Vol 47 (20) ◽  
pp. 2255-2259 ◽  
Author(s):  
M. Salomon ◽  
C. Hojvat

Coulomb excitation of Br targets and the reaction 80Se(p,γ)81Br were used to populate the low lying excited states of 81Br and an energy level scheme is proposed. The reduced transition probability from the ground state to the first excited state of 81Br (276 keV) has been measured to be B(E2) = 410 ± 40 e2 f4.


1963 ◽  
Vol 41 (6) ◽  
pp. 923-931 ◽  
Author(s):  
G. J. McCallum

The 3.70-Mev level in Al25 has been studied by means of the reaction Mg24(p, γ)Al25 at the 1.49-Mev resonance. Direct angular distribution measurements of the de-excitation gamma radiation support the spin assignment of 7/2− for this level. An E2/M1 amplitude mixing ratio of −0.55 ± 0.2 is found for the 1.79-Mev de-excitation radiation from the fourth excited state to the ground state of Al25. The ratio of the reduced transition probability of the E2 radiation from the 1.79-Mev level to the first excited state is shown to be ~30 times that to the ground state. This result provides further confirmation of rotational band structure in Al25 since the collective model predicts such an enhancement of E2 transitions between rotational bands whereas cross-band transitions are not expected to be enhanced.


1984 ◽  
Vol 37 (2) ◽  
pp. 239 ◽  
Author(s):  
MP Fewell ◽  
RH Spear ◽  
TH Zabel ◽  
AM Baxter

The correction to the value of B(E2; t - ~ t --) due to the effect of the ground-state quadrupole moment was applied with the wrong sign. Thus lines 6 and 7 of p. 507 should read ' ... and the ground-state quadrupole moment produces a decrease of 13%...' Consequently, the result of the experiment is B(E2; t - ~ t -) = 2�6�0�4 e2 fm" corresponding to 3�5 W.u. The conclusions of the paper are not affected.


1970 ◽  
Vol 48 (1) ◽  
pp. 35-45 ◽  
Author(s):  
O. Häusser ◽  
B. W. Hooton ◽  
D. Pelte ◽  
T. K. Alexander ◽  
H. C. Evans

The reorientation effect in Coulomb excitation with 62 MeV 35Cl projectiles was used to measure the static quadrupole moment of the first excited state in 24Mg. From a comparison of the inelastic scattering cross sections at CM scattering angles of 123.1° and 72.8°, a static quadrupole moment of Q = −0.243 ± 0.035 b was deduced. The E2 matrix element connecting the ground state and first excited state was also measured and corresponds to 20.3 ± 1.4 W.u. for the 2+ → 0+ transition. The results are compared with predictions of the rotational model.


2017 ◽  
Vol 474 (16) ◽  
pp. 2713-2731 ◽  
Author(s):  
Athinoula L. Petrou ◽  
Athina Terzidaki

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.


1982 ◽  
Vol 35 (3) ◽  
pp. 301 ◽  
Author(s):  
FC Barker

The contribution to the Coulomb excitation of the first excited state of 170 due to virtual excitation of the giant dipole resonance (GDR) is calculated, using shell model wavefunctions for the ground and first excited states. A large value is obtained.


1980 ◽  
Vol 33 (3) ◽  
pp. 509 ◽  
Author(s):  
RH Spear ◽  
MP Fewell

The reorientation effect in Coulomb excitation has been used to measure the static quadrupole moment Q2+ and B(E2;0+->2+) for the 1�779 MeV first excited state of 28Si. The results obtained are Q2+ = +15�5�3�4 efm2 and B(E2;0+->2+) = 326�20 e2fm4 ? The value obtained for Q2+ confirms the results of other recent determinations using the reorientation effect, and the B(E2; 0+ -> 2 +) value is in excellent agreement with the mean value deduced from previous lifetime determinations. Shell model and Hartree-Fock calculations of Q2+ both give a good account of the experimental result.


1964 ◽  
Vol 42 (6) ◽  
pp. 1311-1323 ◽  
Author(s):  
M. A. Eswaran ◽  
C. Broude

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.


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