Gamma-Ray Yields from Nuclear Reactions and Level Densities of Deformed Nuclei

1966 ◽  
Vol 151 (3) ◽  
pp. 992-999 ◽  
Author(s):  
J. O. Rasmussen ◽  
T. T. Sugihara
Keyword(s):  
Gamma Ray ◽  
Nuclear Reactions ◽  
Deformed Nuclei ◽  
Level Densities

scholarly journals Level densities of Ge74,76 from compound nuclear reactions

2019 ◽  
Vol 99 (5) ◽  
Author(s):  
A. V. Voinov ◽  
T. Renstrøm ◽  
D. L. Bleuel ◽  
S. M. Grimes ◽  
M. Guttormsen ◽  
...  
Keyword(s):  
Nuclear Reactions ◽  
Level Densities

scholarly journals Nuclear burning in collapsar accretion discs

2020 ◽  
Vol 499 (3) ◽  
pp. 4097-4113 ◽  
Author(s):  
Yossef Zenati ◽  
Daniel M Siegel ◽  
Brian D Metzger ◽  
Hagai B Perets
Keyword(s):  
Angular Momentum ◽  
Gamma Ray ◽  
Nuclear Reactions ◽  
Reaction Network ◽  
Accretion Discs ◽  
Late Time ◽  
Rotating Stars ◽  
Stellar Envelope ◽  
Nuclear Burning ◽  
R Process

ABSTRACT The core collapse of massive, rapidly-rotating stars are thought to be the progenitors of long-duration gamma-ray bursts (GRB) and their associated hyperenergetic supernovae (SNe). At early times after the collapse, relatively low angular momentum material from the infalling stellar envelope will circularize into an accretion disc located just outside the black hole horizon, resulting in high accretion rates necessary to power a GRB jet. Temperatures in the disc mid-plane at these small radii are sufficiently high to dissociate nuclei, while outflows from the disc can be neutron-rich and may synthesize r-process nuclei. However, at later times, and for high progenitor angular momentum, the outer layers of the stellar envelope can circularize at larger radii ≳ 107 cm, where nuclear reactions can take place in the disc mid-plane (e.g. 4He + 16O → 20Ne + γ). Here we explore the effects of nuclear burning on collapsar accretion discs and their outflows by means of hydrodynamical α-viscosity torus simulations coupled to a 19-isotope nuclear reaction network, which are designed to mimic the late infall epochs in collapsar evolution when the viscous time of the torus has become comparable to the envelope fall-back time. Our results address several key questions, such as the conditions for quiescent burning and accretion versus detonation and the generation of 56Ni in disc outflows, which we show could contribute significantly to powering GRB SNe. Being located in the slowest, innermost layers of the ejecta, the latter could provide the radioactive heating source necessary to make the spectral signatures of r-process elements visible in late-time GRB-SNe spectra.

scholarly journals Precision measurements on oxygen formation in stellar helium burning with gamma-ray beams and a Time Projection Chamber

2021 ◽  
Author(s):  
Robin Smith ◽  
Moshe Gai ◽  
Sarah Stern ◽  
Deran Schweitzer ◽  
Mohammad Ahmed
Keyword(s):  
Time Projection Chamber ◽  
Gamma Ray ◽  
Nuclear Reactions ◽  
Angular Distributions ◽  
Helium Burning ◽  
Low Energies ◽  
Important Input ◽  
Novel Method ◽  
Time Projection ◽  
First Time

Abstract Stellar Evolution theory relies on our knowledge of nuclear reactions, with the carbon/oxygen (C/O) ratio, at the end of helium burning, being the single most important input. However, the C/O ratio is still not known with sufficient accuracy, due to large uncertainties in the cross section for the fusion of helium with 12C to form 16O, denoted as the 12C(α,γ)16O reaction. We present initial results at moderately low energies using a novel method, which is significantly different from the experimental efforts of the past four decades. Precise angular distributions of the 12C(α,γ)16O reaction were obtained by measuring the inverse 16O(γ,α)12C reaction with gamma-beams and a Time Projection Chamber detector. These allowed us to measure, for the first time, the interference angle of the l = 1 and 2 partial waves contributing to this reaction (φ12), which agrees with predictions based on the unitarity of the scattering matrix.

scholarly journals Zirconium and Yttrium (p, d) Surrogate Nuclear Reactions: Measurement and determination of gamma-ray probabilities: Experimental Physics Report

2017 ◽  
Author(s):  
J. T. Burke ◽  
R. O. Hughes ◽  
J. E. Escher ◽  
N. D. Scielzo ◽  
R. J. Casperson ◽  
...  
Keyword(s):  
Gamma Ray ◽  
Nuclear Reactions ◽  
Experimental Physics

Gamma-ray transition probabilities in deformed nuclei (150 < A ≤ 190)

1975 ◽  
Vol 16 (6) ◽  
pp. 515-579 ◽  
Author(s):  
W. Andrejtscheff ◽  
K.D. Schilling ◽  
P. Manfrass
Keyword(s):  
Gamma Ray ◽  
Transition Probabilities ◽  
Deformed Nuclei

A TPC Detector for Studying Photo-nuclear Reactions at Astrophysical Energies with Gamma-ray Beams at ELI--NP

2018 ◽  
Vol 49 (3) ◽  
pp. 509 ◽  
Author(s):  
M. Ćwiok ◽  
M. Bieda ◽  
J.S. Bihałowicz ◽  
W. Dominik ◽  
Z. Janas ◽  
...  
Keyword(s):  
Gamma Ray ◽  
Nuclear Reactions
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