Nuclear Reactions at Astrophysical Energies with $\gamma $-ray Beams: A Novel Experimental Approach

2016 ◽  
Vol 47 (3) ◽  
pp. 707
Author(s):  
M. Ćwiok
Keyword(s):  
Experimental Approach ◽  
Gamma Ray ◽  
Nuclear Reactions

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

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

GAMMA-RAY ANGULAR CORRELATIONS FROM ALIGNED NUCLEI PRODUCED BY NUCLEAR REACTIONS

1961 ◽  
Vol 39 (6) ◽  
pp. 788-824 ◽  
Author(s):  
A. E. Litherland ◽  
A. J. Ferguson
Keyword(s):  
Angular Correlation ◽  
Gamma Rays ◽  
Gamma Ray ◽  
Nuclear Reactions ◽  
Residual Nucleus ◽  
Incident Beam ◽  
Nuclear Spectroscopy ◽  
Population Parameters ◽  
Axially Symmetric ◽  
Angular Correlations

Two general procedures for the measurement and analysis of angular correlations of gamma radiations from nuclear reactions are described which have wide applications in nuclear spectroscopy for the determination of spins and gamma-ray multipolarities. Cases can be studied by these methods when the reaction proceeds through a compound state too complex to allow the usual analysis to be made, for example where several levels overlap or where direct interaction is dominant. The basis of these procedures is to exploit the simplifications brought about by making the reacting system axially symmetric. A sharp gamma-ray-emitting state formed in such a system can be regarded as aligned and described in terms of a relatively small number of population parameters for the magnetic substates. In the first procedure, a state Y* is prepared by a nuclear reaction X(h1h2) Y* in which h2 is unobserved. The state Y* has axial symmetry about the beam axis. From coincidence angular correlation measurements of two cascade gamma rays from Y*, the unknown population parameters for Y* together with the nuclear spins and gamma-ray multipolarities can be determined. In the second procedure, h2 is measured in a small counter at 0° or 180° relative to the incident beam. It is then shown that the quantum numbers of the magnetic substates of Y* which can be populated do not exceed the sum of the spins of X, h1, and h2. In cases where the sum of the spins does not exceed [Formula: see text], the angular correlation of the gamma rays from the aligned state depends only upon the properties of the states in the residual nucleus. Theoretical expressions for angular correlations from aligned states are given, together with a method whereby existing extensive tables of coefficients can be used to calculate them. The results of two recent experiments are discussed as examples.

scholarly journals Activation cross section data of deuteron induced nuclear reactions on rubidium up to 50 MeV

2021 ◽  
Vol 57 (1) ◽  
Author(s):  
Ferenc Tárkányi ◽  
Alex Hermanne ◽  
Ferenc Ditrói ◽  
Sándor Takács ◽  
Anatolij V. Ignatyuk ◽  
...  
Keyword(s):  
Cross Sections ◽  
Gamma Ray ◽  
Nuclear Reactions ◽  
Thick Target ◽  
Gamma Ray Spectrometry ◽  
Activation Cross Section ◽  
Experimental Database ◽  
Practical Applications ◽  
Section Data ◽  
First Time

AbstractActivation cross sections of the $$^{\mathrm {nat}}\hbox {Rb (d,xn)}^{87\mathrm {m,85m,85g,83,82}}\hbox {Sr}$$ nat Rb (d,xn) 87 m , 85 m , 85 g , 83 , 82 Sr , $$^{\mathrm {nat}}\hbox {Rb(d,x)}^{\mathrm {86,84,83,82m}}\hbox {Rb}$$ nat Rb(d,x) 86 , 84 , 83 , 82 m Rb and $$^{\mathrm {nat}}\hbox {Rb(d,x)}^{85\mathrm {m}}\hbox {Kr}$$ nat Rb(d,x) 85 m Kr nuclear reactions have been measured for the first time through an activation method combining the stacked foil irradiation technique and gamma-ray spectrometry. The provided cross sections from the present investigation are all new, in such a way contribute to the completeness of the experimental database. The experimental cross sections were compared with the theoretical prediction in the TENDL-2019 TALYS based library and with our calculation using ALICE-D and EMPIRE-D model codes in order the improve their predictivity. Thick target production yields were calculated form the new cross sections for all investigated radioisotopes. Practical applications of the results are shortly discussed.

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