Study of key resonances in the 30P(p,γ)31S reaction in classical novae

Among reactions with strong impact on classical novae model predictions, 30P(p,γ)31S is one of the few remained that are worthy to be measured accurately, because of their rate uncertainty, as like as 18F(p,α)15O and 25Al(pγ)26Si. To reduce the nuclear uncertainties associated to this reaction, we performed an experiment at ALTO facility of Orsay using the 31P(3He,t)31S reaction to populate 31S excited states of astrophysical interest and detect in coincidence the protons coming from the decay of the populated states in order to extract the proton branching ratios. After a presentation of the astrophysical context of this work, the current situation of the 30P(p,γ)31S reaction rate will be discussed. Then the experiment set-up of this work and the analysis of the single events will be presented.

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Study of Atomic Populations, Electromagnetically Induced Transparency, and Dispersive Signals in a λ-Type System Under Various Decoherence Effects

Ukrainian Journal of Physics ◽

10.15407/ujpe64.3.197 ◽

2019 ◽

Vol 64 (3) ◽

pp. 197

Author(s):

R. Hazra ◽

Md.M. Hossain

Keyword(s):

Excited States ◽

Electromagnetically Induced Transparency ◽

Energy Levels ◽

Type System ◽

Field Approximation ◽

Peak Height ◽

Probe Field ◽

Set Up ◽

Induced Transparency ◽

Atomic Populations

We have theoretically studied the atomic populations, electromagnetically induced transparency (EIT), and dispersion in a three-level Λ-type system. The density matrix equations are set up with regard for the relaxation of populations of the ground states, and the optical Bloch equations are solved analytically in the weak probe field approximation. Decoherence effects in the ground and excited states on the EIT line shape and dispersive signals are studied, and it is found that the EIT line width increases and the peak height decreases, as the decoherence rates increase in the ground and excited states. On the other hand, we have observed that the dispersive signals are steeper and of high contrast for the lower decoherence rates in the ground and excited states. We have also analyzed the variations of atomic populations of the energy levels at the pump Rabi frequency, as well as the decoherence rate in the ground state.

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Non-standard s-process in massive rotating stars

Astronomy and Astrophysics ◽

10.1051/0004-6361/201833283 ◽

2018 ◽

Vol 618 ◽

pp. A133 ◽

Cited By ~ 17

Author(s):

Arthur Choplin ◽

Raphael Hirschi ◽

Georges Meynet ◽

Sylvia Ekström ◽

Cristina Chiappini ◽

...

Keyword(s):

Critical Velocity ◽

Rotation Rate ◽

Reaction Rate ◽

Massive Stars ◽

Strong Impact ◽

Light Elements ◽

Rotating Stars ◽

Stellar Models ◽

Fast Rotating

Context. Recent studies show that rotation significantly affects the s-process in massive stars. Aims. We provide tables of yields for non-rotating and rotating massive stars between 10 and 150 M⊙ at Z = 10−3 ([Fe/H] = −1.8). Tables for different mass cuts are provided. The complete s-process is followed during the whole evolution with a network of 737 isotopes, from hydrogen to polonium. Methods. A grid of stellar models with initial masses of 10, 15, 20, 25, 40, 60, 85, 120, and 150 M⊙ and with an initial rotation rate of both 0% or 40% of the critical velocity was computed. Three extra models were computed in order to investigate the effect of faster rotation (70% of the critical velocity) and of a lower 17O(α, γ) reaction rate. Results. At the considered metallicity, rotation has a strong impact on the production of s-elements for initial masses between 20 and 60 M⊙. In this range, the first s-process peak is boosted by 2−3 dex if rotation is included. Above 60 M⊙, s-element yields of rotating and non-rotating models are similar. Increasing the initial rotation from 40% to 70% of the critical velocity enhances the production of 40 ≲ Z ≲ 60 elements by ∼0.5−1 dex. Adopting a reasonably lower 17O(α, γ) rate in the fast-rotating model (70% of the critical velocity) boosts again the yields of s-elements with 55 ≲ Z ≲ 82 by about 1 dex. In particular, a modest amount of Pb is produced. Together with s-elements, some light elements (particularly fluorine) are strongly overproduced in rotating models.

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Branching ratios in the radiative decay of helium doubly excited states

Physical Review A ◽

10.1103/physreva.72.052512 ◽

2005 ◽

Vol 72 (5) ◽

Cited By ~ 17

Author(s):

M. Coreno ◽

K. C. Prince ◽

R. Richter ◽

M. de Simone ◽

K. Bučar ◽

...

Keyword(s):

Excited States ◽

Radiative Decay ◽

Branching Ratios ◽

Doubly Excited States ◽

Doubly Excited

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Flash photolysis study of the methylperoxy + methylperoxy reaction: rate constants and branching ratios from 248 to 573 K

The Journal of Physical Chemistry ◽

10.1021/j100365a035 ◽

1990 ◽

Vol 94 (2) ◽

pp. 700-707 ◽

Cited By ~ 43

Author(s):

P. D. Lightfoot ◽

R. Lesclaux ◽

B. Veyret

Keyword(s):

Rate Constants ◽

Reaction Rate ◽

Flash Photolysis ◽

Branching Ratios ◽

Reaction Rate Constants

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Energy levels, Auger branching ratios, and radiative rates of the core-excited states of B-like carbon

The Journal of Chemical Physics ◽

10.1063/1.3643334 ◽

2011 ◽

Vol 135 (12) ◽

pp. 124309 ◽

Cited By ~ 11

Author(s):

Yan Sun ◽

Feng Chen ◽

Bing Cong Gou

Keyword(s):

Excited States ◽

Energy Levels ◽

Branching Ratios ◽

The Core

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Sextische Zentrifugalverzerrungskonstanten und Mikrowellen-spektren bis 130 GHz von 12C32SF35Cl

Zeitschrift für Naturforschung A ◽

10.1515/zna-1977-0715 ◽

1977 ◽

Vol 32 (7) ◽

pp. 754-760

Author(s):

R. Hamm ◽

H. Günther ◽

W. Zeil

Keyword(s):

Excited States ◽

Energy Matrix ◽

Centrifugal Distortion ◽

Absolute Value ◽

Degree Of Exactness ◽

Symmetric Rotor ◽

Energy Formula ◽

Sufficient Degree ◽

Set Up ◽

Centrifugal Distortion Constants

Abstract It has been demonstrated that Watson's energy formula for the centrifugal distorted rotor is no longer sufficient for highly excited states. For the CSFCl molecule, the formula can only be used up to a limit of about J = 30. Beyond this rotational quantumnumber Watson's sextic Rotational Hamiltonian should be used for fitting the rotational energy parameters. Good results were obtained up to J = 70 using the sextic Hamiltonian and diagonalizing numerically the energy matrix set up in the rigid symmetric rotor basis. The sextic centrifugal distortion constants could be determined to a sufficient degree of exactness, i. e. the absolute value of the constants is considerably greater than the errors.

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